Note: Descriptions are shown in the official language in which they were submitted.
~2~3~5
PROCESSES REL~TING TO THE EXTRACTION OF METALS
FROM LATERITES AND OCEAN MANGANESE NODULES
TECHNICAL FIELD
The processes of the present invention are in-
tended for the treatment of certain ores, generally
considered lower grade, as a result of which certain
desirable metals can be extracted. One major ~ource of
these ores includes the terrestrial oxide type nickel ores
or laterites, so named because they result from a process
known as laterization whereby ultramafic magma undergoes
prolonged and continuous'decomposition and weathering.
After intense oxidation, differential leachings
and precipitations and differential dissolution of magnesia
and silica from the ultramafic rock, the residual surface
layers of the deposit become enriched in nickel, cobalt,
iron, chromium, manganese and aluminum. Further enrichment
in nickel occurs in the underlying layers. As is known, a
lateritic deposit, somewhat idealized, is characterized by a
vertical composition profile with a hematitic cap or over-
burden under which lies nickeliferous Limonite, followed by
altered Peridotite and finally unaltered Peridotite.
As a general rule, cobalt, iron and manganese
concentrations are higher in the upper regions of the
vertical profile and decrease with depth. Similarly,
nickel, magnesium and silica concentrations become greater
as the depth increases. The Limonitic ore is particularly
suited for treatment by the processes of the present inven-
tion. It typically comprises a high iron phase, goethite
(alpha-FeOOH) and a lower amount of manganese oxide. The
goethite contains a high fraction of the total nickel
content, e.g.~ 75 to 95 percent of the nickel and low
fraction of the total cobalt content, e.g., 0 to 20 percent
of the cobalt. The manganese oxide phase is roughly
reversed with a high cobalt content, e.g., 80 to 100 percent
of the cobalt and a lower nickel c ntent, e.g., 5 to 15
percent of the nickel. The overall result is that Limonitic
;~
~ 5873
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ores provide a higher amount of nickel than cobalt.
Manganese ocean or sea nodules offer a composition
generally opposite that of the Limonitic ores, that is,
having a greater manganese oxide content than iron oxide
content. Composition of the manganese nodules is analogous
to what has been observed for the limonitic ores and that is
a variance depending upon location in the ocean. Inasmuch
as manganese nodules form in oxidizing environments, ca~ions
with higher valencies predominate over reduced valence
' 10 stateS.
In order to access and extract, the nickel and
cobalt, the ore matrix mu'st be treated chemically, that is,
' converted or solubilized. Commonly, this can be achieved by
j reducing Fe(III~ to Fe(II) or Fe and MnO2 to Mn(II).
Thermodynamically, such reductions are possible by carbon
monoxide or hydrogen in acidic or alkaline solutions.
However, kinetically, such reductions do not occur under
reasonable temperature and pressure unless a catalyst is
provided.
! 2Q Both laterites and manganese ocean nodules will be
important as a future source for nickel and cobalt. The
present invention is directed toward treatment of these and
like ores which are generally considered to be low grade as
well as not being amenable to conventional beneficiation
techniques, e.g., nickel and cobalt content is too low for
an economically feasible recovery. However, given high
enough recoveries, such as greater than 90 percent, and low
' energy requirements, e.g., temperature at or near 30 to 60
C and pressure between l to 10 atmospheres, the processes
set forth herein are economically feasible. An important
process of the present invention shall be referred to herein
¦ as the ARIS process for Ambient Reduction by Intermediary
Solutions.
BAC~GROUND ART
A variety of methods are known for the recovery of
nickel and cobalt from lateritic ores. One method, known as
~ 3'~S 5873
--3--
the high pressure sulfuric acid leaching process, ~ , the
Moa Bay process, is practiced by pulping the ore to
specific mesh and solids and then selectively leaching the
nickel and cobalt with sulfuric acid at elevated temperature
and pressure. After proper washing and pH adjustment, the
leached pulp is subjected to sulfide precipitation at
elevated temperature and pressure to obtain the nickel and
cobalt but not without oxidation, additional pH adjustment
and selective recovery steps are performed.
The foregoing process is discussed in greater
detail in a U.S. patent owned by AMAX, Inc., ~o. 4,044,096,
which also employs a high' pressure sulfuric acid leaching
step of laterites at elevated temperature. The ore is first
slurried and autoclaved, leached with acid and subsequently
discharged into a flash tank to create turbulence.
U.S. Pat. No. 3,761,566 provides another method
for leaching lateritic ores. Leaching is conducted at
elevated temperature and pressure with waste solutions of
ferrous sulfate.
Similarly, processes ars known for the recovery of
I nickel and cobalt from manganese sea nodules. U.S. Pat. No~
4,085,188 provides a reductive leaching of sea nodules in an
aqueous ammoniacal medium and with a reducing agent such as
SO2, sulfides, NO2 or metallic iron. Manganese is reduced
from its tetravelent state to manganous carbonate and,
nickel, cobalt and copper are extracted.
U.S. Pat~ No. 3,983,017 provides for the recovery
of copper, nickel, cobalt and molybdenum from sea nodules by
I leaching with an aqueous ammoniacal solution containing
¦ 30 cuprous ions. Carbon monoxide is employed as a reductant
for cupric ions in order to regenerate cuprous ions for
the initial leaching step.
Once metals have been solubilized they mut be
removed from solution in order to complete the recovery
process. Recovery preferably does not consume costly
materials nor does it provide useless or waste by-products.
One process for the recovery of copper, silver and mercury
5~73
~"0 . . .
- ~24~3'~
~ .
~ -4-
is described in UaS~ Pat. No. 3,820,979 which calls for
contacting an aqueous solution of the metal with a solution
of a quinonic compound in an organic solvent. After the
metal precipitates and is separated, the organic phase is
separated and the quinonic compound is optionally reduced
for subsequent use.
Another process for the recovery of copper from
acidic solutions is set forth in my U.S. Pat. No. 4,038,070
which provides for reduction of cupric ions to cuprous ions
with hydrogen i'n the presence of a cuprous stabilizing
ligand such as acetonitrile to produce cuprous~nitrile
complexes that can be dis'proportionated to produce copper
metal and cupric ions.
A similar process which employs a quinolic
15 reductant is described in my U.S. Pat. No. 4,095,975 which
also provides for the recovery of copper from acidic
solutions. The copper solution is initially contacted with
a quinolic reductant and an aqueous nitrile-solubilized in a
water immiscible solvent to produce a nitrile stabilized
cuprous solution and an organic solution of the oxidized
quinolic compound. By driving off the nitrile, the cuprous
ions disproportionate, producing equimolar quantities of
copper metal and cupric ions. The quinolic compound can be
reduced by hydrogen gas.
Notwithstanding the disclosures of the foregoing
art, more economic processes for the selective extraction
of desired metals such as nickel and cobalt have not
appeared heretofore. Such processes should be characterized
by low temperature and low pressure parameters and almost
30 quantitative recoveries. By-products are desirably neither
harmful nor costly to generate or dispose. Recycling adds
to the economy and is desirably accomplished without resort
to expensive reactants or processing conditions. Again,
the body of art known to me has not met all of these
35 requirements.
a634S
~-- 4a -
SUMMARY OF THE INVENTION
The invention relates to a process for the extraction of
ferrous, manganous and nonferrous metals from iron oxide and
manganese oxide containing ores by reduction leaching comprising
the steps of:
contacting the pulverized ore with a stabilized acidic
cuprous ion solution cu~L in a suitable reactor at a temperature
of up to about 90C while maintaining the pH between about 1.5
and 2.5 with acid to form a slurry, wherein L is a stabilizing
ligand selected from the group consisting of CO, XRCN and Cl-, X
being -H or -OH and R being aliphatic having from one to about
four carbon atoms;
separating the slurry into a solid tailings portion and a
pregnant liquor, the pregnant liquor containing solubilized
ferrous, manganous, cupric and other nonferrous metal ions;
selectively extracting the solubilized metal ions; and
regenerating the cuprous ion solution from the solubilized
cupric ions and the ligand, L in the presence of a reductant.
In another aspect of the present invention, there is
provided a process for the regeneration of stabilized cuprous ion
solution~, usable as reductants, from acid~c cupric ion solutions
comprising the steps of:
dividing the cupric ion solution into first and second
streams;
combining the first stream with a quinolic compound
selected from the group consisting of quinol and anthraquinols to
form a three phase slurry consisting essentially of free copper
metal, an aqueous acid phase and the corresponding quinonic
compound;
separating the quinonic compound from the copper metal and
aqueous acid; and
combining the second stream with the copper metal and
aqueous acid and with a stabilizing ligand L, where L is CO or
XRCN and wherein X is selected from the group consisting of -H
~;~463 ~5
- 4b -
and -OH and R is an aliphatic radical having one to four carbon
atoms, whereby the stabilized cuprous ion solution, Cu+L is
formed.
In a further aspect of the present invention there is
provided a process for the regeneration of stabilized cuprous ion
solutions, usable as reductants, from acidic cupric ion solutions~
comprising the steps of:
reducing the solubilized cupric ions with CO to form a
slurry comprising copper metal, cupric ions and acid; and
cooling and combining the slurry with a stabilizing ligand
L, where L is CO or XRCN and wherein X is selected from the group
consisting of -H and -OH and R is an aliphatic radical having one
to four carbon atoms, to form the stabiliæed ion solution Cu'L.
In still a further aspect of the present invention, there is
provided a process for the regeneration of stabilized cuprous ion
solutions, usable as reductants, from acidic cupric ion solutions
comprising the steps of:
reducing the solubilized cupric ions with syngas in an
autoclave operating at a pressure of between about 1.5 and 5.0
MPa and at a temperature of from about 150 to 280 C to form a
slurry comprising copper metal, cupric ions, cuprous ions and
acid; and
cooling and combining the slurry with a stabilizing ligand
L, where L is CO or XRCN and wherein X is selected from the group
consisting of -H or -OH and R is an aliphatic radical having one
to four carbon atomsS to form the stabilized ion solution Cu+L.
,
' i .,
. .
5873
~11 ~'3 A ~` ~
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DISCLOSURE OF THE INVENTION
The present invention provides several processes
employing various combinations of steps that either allow
selective leaching of metal ions from various ores with
intermediary solutions or the generation of such solutions.
The leaching processes are based upon an acid leach step
employing stabilized cuprous ions and, in one instance, a
combination thereof with ferrous ions. Leaching is con-
ducted at low temperatures under 90 C and low pressures,
under 1.4 MPa and at a pH of about 1.5 to 2.5.
A variety of ores can be treated as will be dis-
cussed hereinbelow in gre'ater detail. Such ores basically
comprise iron oxide and manganese oxide ores which provide
nickel and cobalt, respectively. Nickel and cobalt
recoveries from the ores, employing these processes, will
; usually equal or exceed 90 percent. The intermediary solu-
tions employed produce no by-products harmful to the
environment such as SO2, H2S, NO and the like. Generally
the final waste materials will be inert and directly
suitable for landfills.
In general, one process for the extraction of
ferrous, manganous and nonferrous metals from iron oxide and
manganese oxide containing ores by reduction leaching com- -
prises the steps of contacting the pulverized ore with a
stabilized acidic cuprous ion solution Cu L at a temperature
of up to about 65 C while maintaining the pH between about
j 1.5 and 2.5 with acid to form a slurry, wherein L is a
stabilizing ligand selected from the group consisting of CO,
XRCN and Cl , X being -H or -OH and R being aliphatic having
from one to about four carbon atoms; separating the slurry
into a solid tailings portion and a pregnant liquor, the
pregnant liquor containing solubilized ferrous, manganous,
cupric and other nonferrous metal ions; selectively
extracting the solubilized metal ions and, regenerating the
cuprous ion solution from the solubilized cupric ions and
the ligand, L, in the presence of a reductant.
Additional steps of the first process include
5873
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~2~3~i
removing a portion of the cuprous ions from the cuprous ion
solution after the step of regenerating by drawing off a
slipstream of the stabilized cuprous ion solution, allowing
the slipstream to disproportionate, forminy free copper
S metal and cupric ions and, separating the copper metal from
the cupric ions.
Alternatively, a portion of the cupric ions can be
removed from the cupric ion solution before the step of
reyenerating by combining the solubilized cupric ions with a
quinolic compound selected from the group consisting of
quinol, anthraquinols and naphthoquinols to form a three
phase slurry consisting e~ssentially of free copper metal, an
aqueous acid phase and the corresponding quinonic compound
and, separating the copper metal therefrom.
A second major process of the present invention
also provides for the extraction of ferrous, manganous and
nonferrous metals from iron oxide and manganese oxide
containing ores by reduction leaching and comprises the
steps of contacting the pulverized ore with a stabilized
acidic cuprous ion solution Cu L at a temperature of up to
about 65 C while maintaining the pH between about 1.5 and
2.5 with acid to form a slurry, wherein L is a stabilizing
ligand selected from the group consisting of CO, XRCN and
Cl , X being -H or -OH and R being aliphatic having from one
to about four carbon atoms; separating the slurry into a
solid tailings portion and a pregnant liquor, the pregnant
liquor containing solubilized ferrous, manganous, cupric and
other nonferrous metal ions and, selectively extracting the
solubilized metal ions.
Another process provided by the present invention
can be employed for the regeneration of stabilized cuprous
ion solutions, usable as reductants, from acidic cupric ion
solutions. It comprises the steps of combining the
solubilized curric ions with CO as a stabilizing ligand and
a quinolic com~ound selected from the group consisting of
quinol, anthraquinols and naphthoquinols at a pressure of
from about 0 10 to about 1.4 MPa and at a temperature of
5873
~Z9L~;3~5
from about 20 to 90 C to form an aqueous CuCO+ lixiviant
and the corresponding quinonic compound, separating the
lixiviant from the quinonic compound and, regenerating the
quinolic compound from the quinonic.
Another process for the regeneration of stabilized
cuprous ion solutions from acidic cupric ion solutions
comprises the steps of dividiny the cupric ion solution into
first and second streams, combining the first stream with a
quinolic compound selected from the group consisting of
quinol, anthraquinols and naphthoquinols to form a three
phase slurry consisting essentially of free copper metal, an
aqueous acid phase and th'e corresponding quinonic compound,
separating the quinonic compound from the copper metal and
aqueous acid and, cooling and combining the second stream
with the copper metal and aqueous acid and with a
stabilizing ligand L, where L is CO or XRCN, whereby the
! stabilized cuprous ion solution, Cu L is formed.
Yet another process for the regeneration of
stabilized cuprous ion solutions from acidic cupric ion
20 solutions comprises the steps of reducing the solubilized
cupric ions with CO to form a slurry comprising copper
I metal, cupric ions and acid and, combining the s~urry with a
¦ stabilizing ligand L, where L is CO or XRCN, to form the
stabilized ion solution Cu L.
Still another process for the regeneration of
t stabilized cuprous ion solutions from acidic cupric ion
; solutions comprises the steps of reducing the solubilized .
cupric ions with syngas in an autoclave operating at a
pressure of between about 0.5 and 5.0 MPa and at a tem-
perature of from about 150 to 260 C to form a slurry
comprising copper metal, cupric ions and acid and, combining
the slurry after cooling to below 90 C with a stabilizing
ligand L, where L is CO or XRCN, to form the stabilized ion
solution Cu L.
Any of the foregoing individual processes for
regeneration of the stabilized cuprous ion solutions can be
employed in conjunction with the two extraction processes
~ ~ 5873
63~
presented hereinabove~ Insofar as those processes are
concerned, yet another manner for the regeneration, where L
is XRCN, includes the steps of combining the solubilized
cupric ions with the ligand XRCN and a ~uinolic compound
selected from the group consisting of quinol, anthraquinols
and naphthoquinols at a pressure of from about 0.1 to about
0.2 MPa and at a temperature of from abou~ 20 to 65 C to
form a CuXRCN lixiviant and the corresponding quinonic
compound, separating the lixiviant from the quinonic com-
pound and, regenerating the quinolic compound from thequinonic.
Still another ~ocess for the regeneration, in
conjunction with the extraction processes, includes the
steps of reducing the solubilized cupric ions with hydrogen
to form a slurry comprising copper metal, cupric ions and
acid and, combining the slurry with the ligand L, where L is
CO or XRCN, to form the stabilized ion solution Cu L.
A separate process for the extraction of ferrous,
manganous and nonferrous metals from iron oxide and
manganese oxide containing ores by reduction leaching is
provided which comprises the steps of contacting the pul-
verized ore with a stabilized acidic cuprous ion solution
Cu+L at a temperature of up to about 65 C while maintaining
the pH between about 1.5 and 2.5 with acid to form a slurry,
wherein L is a stabilizing ligand selected from the group
consisting of CO, XRCN and Cl , X being -H or -OH and R
being aliphatic having from one to about four carbon atoms,
separating the slurry into a solid tailings portion and a
pregnant liquor, the pregnant liquor containing solubilized
ferrous, manganous, cupric and other nonferrous metal ions;
; feeding the pregnant liquor to a second pulverized ore feed,
containing, at least partially, manganese oxide ore to form
a second slurry; separating the second slurry into a solid
tailings portion containing sub~antially unsolubilized iron
oxide ore and a second pregnant liquor containing solubilized
ferrous, manganous, cupric and other nonferrous ions and,
selectively extracting the solubilized metal ions.
5873
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Finally, a process for the selective extraction of
manganous and nonferrous metals from iron oxide containing
ores by reduction leaching is provided which comprises the
steps of contacting the pulveri~ed ore with an acidic Fe2
solution in a suitable reaction at a temperature of up to
about 90 C while maintaining the p~ between about 1.5 and
2.5 with acid to form a slurry, separating the slurry into a
solid tailings portion and a pregnant liquor, the pregnant
liquor containing solubilized ferric, manganous, cupric and
other nonferrous metal ions and, selectively extracting the
solubilized metal ions.
~.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic diagram illustrating a major
overall process of the present invention, the ARIS process;
Fig. 2 is a schematic diagram illustrating an
independent process for the regeneration of cuprous ion
solutions with various stabilizing ligands which can be
employed in conjunction with the ARIS process;
Fig. 3 is a schematic diagram illustrating an
alternative independent process for cuprous ion regenera-
tion which can be employed in conjunction with the ARIS
process;
Fig. 4 is a schematic diagram illustrating an
alternative process for cuprous ion regeneration which can
be employed in conjunction with the ARIS process;
Fig. 5 is a schematic diagram illustrating an
alternative process for cuprous ion regeneration which can
be emplo~ed in conjunction with the ARIS process;
Fig. 6 îs a schematic diagram depicting a process
for the removal of copper from a process such as depicted in
Fig. l;
Fig. 7 is a schematic diagram illustrating another
process of the present invention for the reduction of ores;
Fig. 8 is a schematic diagram illustrating another
overall process of the present invention for the reduction
of ores; and
~ 3~5 5873
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Fig. 9 is a schematic diagram depicting another
process for the reduction of ores.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
- 5 Practice of the present invention leaches or
dissolves the Goethite phase, Fe3 OOH and Mn4 2 phase in
laterites and similar iron ores to provide Ni2~ and Co2 by
reducing the iron and manganese to Fe2 and M2 states. The -
process wil also accomodate manganese sea nodules as the
feed ore to reduce manganese and iron to 2+ states and
provide Ni2 and Co2+ for subsequent separation and
recovery. The ~arious processes employ a Cu /ligand ~)
reductant and include steps for the regeneration thereof.
Before proceeding with the details of the processes,
a brief discussion of the two ores particularly suited for
treatment thereby shall be provided. First, regarding the
laterites, the limonitic or high iron type is preferred.
Other ores, having a relatively high Mg and Si content,
could pose process problems such as acid consumption and
large quantities of magnesium by-products. A typical
chemical composition by weight percent for limonitic ore
appears in Table I.
As to the manganese sea nodules, any type can be
treated by the process of the present invention irrespective
of the ocean, depth, or the environment, e.g., seamount,
ridges, continental borderlands and the like. An average
chemical composition (partial), by weight percent, for sea
nodules also appears in Table I.
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TABLE I
Partial Chemical Composition of Feed Materials
Elements Lat ritesa Mn nodulesb
! 5 Ni 1.20 0.491
I Fe 33.20 15.61
Co 0.15 0.30
Mn 0.48 16.17
Cr 1.67 0.001
Mg 7.25 1.82
Al 1.73 3.10
Si '8.93 8.62
Cu 0.01 ~.26
I
a) U.S. Bureau of Mines analysis of Gasquet Mountain
Laterites
b) Marine Manganese Deposits, G. P. Glasby ed., Elsevier
Oceanographic Series, (1977).
The remainder of the ores will consist of various
oxides, clay, minerals and the like many of which are
neither useful nor necessarily recoverable by the process of
the present invention. It is to be understood that as the
iron, manganese, nickel and cobalt are selectively leached,
the waste material or tailings become enriched in the
unleached materials. Some, such as chromium, are not
substantially removed by the present invention and therefore
their recovery by alternative means from the tailings may be
economically feasible, given the greater concentration
therein.
The ARIS process constitutes a preferred mode of
the present invention and is characterized by being a low
temperature, low pressure acid leach process. Leaching of
the Fe2O3 anc MnO2 ore components in acidic aqueous solu
tions with the stabilized cuprous ions results in the
accessibility of cobalt, nickel and copper with minimal
leaching of chromium, magnesium and precious metals other
5873
63~5i
than silver. The cuprous ions in the leach solution are
stabilized against disproportionation with a ligand L such
as CH3CN, CO or Cl to form a complex. During the leaching
step the cuprous ions are oxidized to cupric which can be
recycled and regenerated as cuprous in several additional
steps.
As noted hereinabove, the process is adapted for
treatment of high iron-containing (limonitic~ laterites,
which can contain some manganese, and manganese sea nodules,
which also contain some iron. These iron and manganese ores
contain non-ferrous metals such as nickel, cobalt and copper
which can be extracted in'nearly quantitative yields.
Although particle size is not critical to practice
of the present invention, it i5 generally understood in the
art that a large surface area greatly reduces the reaction
time and, therefore, the ore, terrestrial or sea nodule, is
ground and milled by any suitable means to reduce the size
to about -100 mesh.
The ore is first sub~ected to a redox leach step
, 20 which occurs at a pH o~ from about 1.5 to 2.5 and preferably
; less than about 2. Non-oxidizing acids are employed such as
sulfuric, hydrochloric and the like with sulfuric being
preferred. The leaching step should be monitored as to pH
and additional acid provided on demand in order to maintain
a steady and low pH.
The reducing agent for this step is the cuprous
ion. Inasmuch as it is not stable in acid medium, it is
complexed with a recyclable ligand such as CH3CN or CO.
~ While both are highly satisfactory, carbon monoxide is
¦ 30 preferred as will be discussed hereinbelow. The complexed
~, cuprous ion solution, designated at Cu Lx where L is the
! ligand and x is 1 or 2; can be provided from a separate
supply in the processing stream. During the reduction
leaching, it becomes oxidized to the cupric stage while iron
and manganese are reduced. If desired, the cupric ions can
be withdrawn from the system for other use or treatment or
even discarded as waste; however, economics will most likely
~ 46~S ~ 5873
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favor a recycling stream whereby cuprous ions are regenerated.
The overall redox leaching reactions for the two
basic ores discussed herein are embodied in the following
equations:
I Laterite (and Fe3 phase in Mn nodules)
2Fe3 OOH ~ (Cu LX)2SO4 + 3H2SO4 -
ore redox leachant
2FeSO4 ~ 2CuSO4 + 4H2O + (Ni ,Co ~ + 2xL
pregnant liquor
II Mn nodules (and M~n4 phase in laterites)
Mn4 2 + (Cu Lx)2S4 + 2H2S4
redox leachant
MnSO4 + 2CuSO4 + 2H2O + (Ni ,Co ) + 2xL
pregnant liquor
Equations I and II could be modified as will be understood
by those skilled in the art where hydrochloric acid is
substituted for sulfuric.
¦ Moreover, as stated hereinabove the ligand L can
also be Cl . Those skilled in the art will appreciate that
an excess of anion is required to maintain copper soluble
in the process solution and therefore excess hydrochloric
; acid or other chlorides such as MgC12 should be present.
While the work which is discussed hereinbelow exemplifies
¦ two of the ligands, CO and CH3CN, it is to be understood
! that Cl could also be employed and that the present inven-
tion does not exclude this ligand.
After the appropriate time, the leached ore is
separated as to liquids, solids and gases according to known
engineering techniques. The ligand, CO or CH3CN is with-
drawn in one stream for recyc.ing if desired; the pregnant
liquor containing Fe2 , Mn2 , Cu2+, Ni2+ and Co2+ is with-
drawn for extraction of nickel and cobalt and/or recycling
of the other metals. Solid waste material is easily
~ 5873
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separated and discarded or separately treated for extraction
of chromium and possibly precious metals such as Au, Pd, Pt
and Rh wherever analysis indicates a sufficient content to
make extraction feasible. Generally, the insoluble residue
or waste will be enriched in these metals, as the process of
the present invention does not solubilize them. One
precious metal, silver, is solubilized where the ligand is
XRC~. It can be removed by cementation with copper powder.
Regarding the regeneration of the cuprous ion
reductant, the cupric salt from the redox leaching can be
reduced with a quinolic compound, ~H~ which itself is
oxidized to the quinone Q'according to the following
equation:
III Regeneration of (CuL2)2 SO4 Reductant
2Cu SO4 + QH2 + 4L
(aqueous) (organic)
(CUL2)2so4 + H2S4 Q
(aqueous) (organic)
Alternatively, the cuprous ions can also be regenerated via
H2 or CO or syngas, H2/CO, as will be discussed hereinbelow.
~ith reference now to the drawings and Fig. 1, the
ARIS process shall first be broadly and schematically des-
cribed and then be considered in greater detail, with other
processes of the invention, in subsequent figures. The ore
feed, laterite or manganese nodule properly ground, is
contacted with the aqueous cuprous ion reductant in a
reactor, 10. It is to be understood that the process can be
conducted as a batch or continuously in co-current or counter-
current tanks or as otherwise known, and that the selection
of any particular reactor system does not constitute a
limitation of the present invention. The leaching is done,
in acid medium from a supply 11 with stabilized aqueous
cuprous solution, stream 12. The cuprous solution can be
provided from a recycling step, depicted in box 13.
Leaching time for laterites is approximately 45
minutes, for manganese nodules, it i5 about three minutes.
Leaching is conducted at low temperaturel on the order of
5873
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from about 20 to 90 C, with 50 C being pre~erred.
Pressure is also low, ranging from atmospheric up to about
15 atmospheres ~1.5 MPa). Where the complexing ligand is
CH3CN, atmospheric pressure is satisfactory in an atmosphere
such as CO/H~ or other in order to exclude air. Where the
ligand is C~, about 15 atmospheres or less is suitable to
maintain the Cu solubilized to the desired concentrations.
The complexing ligand L can be withdrawn from the
reactor 10 via stream 14 and fed to the recycling step 13
where it will be combined with the regenerated cuprous ions
and returned to reactor 10 via stream 12. Withdrawal from
reactor 10 is especially favored where L is CO.
The reduced slurry from reactor 10 passes via
stream 15 and is allowed to separate and depressurize if
necessary in separator 16. The complexing ligand L can also
be recycled via stream 14 taken from separator 16 to box 13
and the solids portion or tailings passes via stream 17 for
disposal or separate treatments such as for the recovery of
chromium. While chromium recovery is not specifically
provided for in this process, as noted hereinabove, greater
concentrations in the tailings or waste may make recovery
feasible. Stream 18 carries the pregnant liquor, e.g.,
Fe2 , Mn2 , Cu , Ni2 and Co2 as well as any Ag to box 19
where a step or steps for the extraction of iron, manganese,
nickel and/or cobalt and/or silver is conducted. Such steps
are known in the art and therefore are not specifically
described.
The removal of these metal ions at box 19 will
leave a separate aqueous stream 20 of cupric ions to be fed
to box 13 for regeneration of the CUprOUQ ions, with a
stabilizing ligand L. This is accomplished in 13 with a
reductant from stream 21 and the recycle of the ligand via
stream 1~. Before proceeding with a discussion of the
regeneration process in box 13, it should be nc'ed that the
various metals can be removed at other stages such as, by
way of example, iron and manganese first followed by nickel
and/or cobalt at another stage, or vice-versa.
5873
46;~S
- -16-
All of the pr~gnant liquor can also go to the
regeneration step box 13 in which instance nickel and cobalt
will pass ~hrough unchanged and can be extracted from stream
12 prior to reaching reactor 10. Iron could also be with~
drawn from stream 12 or retained with the cuprous ions and
fed to ~eactor 10. Usefulness of ferrous ions in this
manner will be discussed hereinbelow. The manganese ions
would be of no use in reactor 10 and therefore should be
withdrawn from stream 12 or before reaching step 13 in order
to maintain maximum economy. It is to be understood that
the patentability of the processes disclosed herein, as well
as their operability, is hot dependent upon a particular
mode or time for the extraction of Fe2 , Mn2 , Ni2 , or
Co2 from solution. The processes make these metals
available for extraction as they are leached from the ore
feed and provide for regeneration of the stabilized cuprous
ions for reactor 10 in all but one instance to be discussed
hereinbelow.
Now, with respect to the lixiviant regeneration,
cupric to cuprous, which has been depicted in step 13 of
Fig. l! greater detail shall be provided by referring to
Figs. 2-5 and the following explanation. In the regenera-
tion step, the cupric ions are reduced to the cuprous state
and the latter are combined and stabilized with the ligand
L. Reduction of the cupric ions can be achieved in several
manners and in Fig. 2 the use of a quinolic compoundr
designated generally as QH2, shall be discussed first.
Quinol or hydroquinone, the dihydroxy alcohol of
benzene, can be employed for the reduction step as can the
anthraquinols, AQH2, and naphthoquinols, NQH2. Particularly
useful quinolics are disclosed in U.S. Pats. No. 3,820,979,
4,032,331, 4,032,332 and 4,033,765i. These patents
are directed toward the recovery of copper metal, Cu from
cupric ions.
Quinolics, a term used herein for the foregoing
compounds are organic and employed in a water immiscible
.~ ' ' , ' ,
5873
63~S;
solvent mixture comprising non-polar compounds, e.g.,
aromatics such as alkyl toluenes and alkyl naphthalenes and
polar compounds such as alcohols and various esters. As
they react with cupric ions, they become oxidized to the
quinonic species. The quinolic compound selected with the
proper solvent mixture is fed via stream 25 to a reactor 26
as is the cupric ion stream 20 and the ligand via stream 14
or otherwise. The ligand L can be either a nitrile or
carbon monoxide, as discussed hereinabove, or in the
`I 10 instance of a separate process for treatment of cupric ions,
both the ligand stream and the cupric ion stream can be
~ provided from sources oth~r than those resulting from the
', process depicted in Fig. 1.
Dealing first with the instance where L is a
nitrile, and particularly acetonitrile, it is fed to the
reactor 26 and very quickly combines with the cuprous ions
i resulting from the reaction of the quinolic compound and the
acidic cupric ions. The combination of the nitrile ligand
XRCN, with cuprous ions in reactor 26 occurs under pressure
20 of from about 0.1 MPa to about 1.0 MPa at a temperature of
from about 20 to 90 C. Reaction time is short, taking
from about five to 20 minutes. The cupric ions are provided
in an acidic aqueous solution, e.g., CuSO4 and therefore a --
two liquid phase mixture occurs in reactor 26 and passes via
stream 28 to a separator 29. The aqueous, acidic cuprous
ligand portion becomes stream 12 of Fig. 1 which is fed to
` the first reactor 10 for ore reduction.
; The organic phase, which now comprises the --
oxidized quinonic compound, designated herein as a shorthand
notation for quinones, anthraquinones or naphthoquinones
¦ passes via stream 30 to a step 31 for regeneration of the
respective quinolic, designated herein as QH2. Regeneration
or reduction to the quinolic can be achieved with hydrogen
gas over a conventional hydrogenation catalyst such as Raney
nickel, or platinium or palladium supported on conventional
supports at a pressure ranging between about 0.1 and 1.2
MPa and at a temperature of from about 20 to 80 C. The
~ 63~ 5873
.
~18-
process of hydrogen reduction of quinones to their respec-
tive quinols is otherwise known in the production of
hydrogen peroxide and need not be ~urther detailed herein.
~he reduced quinolic, QH2 is fed via stream 25 to the
reactor 26 as was discussed hereinabove. Alternatively, a
fresh supply of quinolic, not ~hown, could be fed to the
reactor 26 where its regeneration is not desired.
The entire ~tep of lixivi~nt regeneration 13 thus
described is set forth in greater detail in my a~ore-
mentioned U.S. Pat. No. 4,095,975. That patent teaches
the recovery of copper metal via disproportionation of
a cu L solution wherein L is acetonitrile. In addition
to acetonitrile other nitriles, designated generally by the
formula XRCN, can be employed where R is aliphatic having
13 from one to about four carbon atoms and x is -OH or H. Such
examples include 2-hydroxy-cyanoethane, acrylonitrile and
priopionitrile. These nitriles are disclosed in u.S. Pat.
No. 3,865,744. Leaching of laterites and sea nodules with
a Cu CH3CN lixiviant is exemplified hereinbelow.
While R has been defined as an aliphatic having
from one to four carbon atoms, other moeities having more
than four carbon atoms are not necessarily inoperable or to
be prec~uded. It has been recognized only that they may not
be economic-~ly-practical and, therefore, an upper limit o~
four carbons has been recited.
Although the particular regeneration of cupric
ions, stabilized with a nitrile ligand, may not be novel per
se~ it is a step in the ARIS process and its use in con-
junction with the redox leaching of ores is believed to be
novel. In lieu of a nitrile ligand, L can also be carbon
monoxide as discussed hereinabove. Where L is CO, the
regeneration of cuprous ions from cupric by reduction with
quinols is not known and is therefore novel ~s a separate
process ~r in conjunction with the other ~teps of the ARIS
process.
B
3~5
--19--
The procedure to follow where ~ is CO is much like
the foregoing description of Fig. 2, in that a quinolic is
again employed, and therefore a total description shall not
be repeated. The ligand CO can be provided via stream 14
from reactor 10 (Fig. 1). It is combined with the quinolic
compound and aqueous acid cupric solution in reactor 26
under pressure of from about 0.1 MPa to as high as 1.5 MPa
at a temperature of from about 20 to 90 C. Reaction is
quick, taking from about five to 20 minutes. Where L is CO,
a pressure in excess of atmospheric must be maintained,
otherwise the ligand will escape and the cuprous ions will
disproportionate to coppe~ metal and cupric ions. Reduction
of cupric to cuprous is exemplified hereinbelow as is the
leaching of lateritic ore with Cu CO lixiviant.
The foregoing regeneration of cuprous ions
occurred in a one-step process, i.e., in reactor 26. A two-
step regeneration is also possible with quinolic compounds
and will be described with reference now to Fig. 3. Practice
of this regeneration requires a division of the aqueous,
acid cupric ion stream 20 into two streams 20A and 20B.
Generally, about 50/50 volumes will be suitable. Stream 20A
is reduced directly to copper metal in reactor 35 with a
quinolic compound QH2 as disclosed hereinabove. In the
absence of a ligand, the cupric ions are reduced directly to
the metal according to the aforementioned U.S. Pat. No.
3,820,979. Stream 36 contains three phases: the organic --
quinone Q with solvents, the aqueous acid H2SO4 from CuSO4
and, the solid copper metal powder. It is passed to a ~
separator 38 wherein the quinonic compound Q is transferred
via stream 39 to a reactor 40 where it is reduced to the
corresponding quinolic QH2 with hydrogen gas in the same
manner as described in Fig. 2. The quinolic is then
returned via str~am 41 to the reactor 35.
The remaining slurry from separator 38 comprising
the aqueous acid and copper metal is fed via stream 42 to a
second reactor 43 to which is fed stream 20B. In this
reactor, the combination of cupric ions and copper metal
~ ~hZ~3~ `` 5873
-20-
with the ligand via stream 14 results in the generation of
the stabilized cuprous ligand or stream 12 for the reactor
10 in Fig. 1. The foregoing two-step regeneration of
cuprous ions stabilized with a ligand is belived to be novel
alone as well as in combination with the other steps of the
ARIS process.
Other two-step processes are also possible which
do not utilize a quinolic compound. Such processes are set
forth in Fig. 4, wherein hydrogen gas is utilized as the
reductant and Fig. 5, wherein carbon monoxide is utilized.
With reference first to Fig. 4, the aqueous acidic cupric
ion stream 20 is fed in a first step to an autoclave 50 to
which is also fed hydrogen gas. This reduction is conducted
at pressures ranging between about 15 and 50 atmospheres,
at a temperature of from about 200 to 280 C and for about
i 0.5 to 3 hours. In the second step, a slurry is fed, from
autoclave 50, via stream 51, comprising copper metal,
cupric ions and H (acid) to a reactor 52 wherein it is
combined, after appropriate cooling, with a ligand such as
~' 20 from stream 14. The resulting stabilized cuprous ion Cu L
and acid H is provided via stream 12 to reactor 10 (Fig.
1). Although this particular regeneration of cuprous ions
may not be novel per se, it is a step in the ARIS process
and its use in conjunction with the redox leaching of ores
is believed to be novel.
Before combining the slurry with the ligand, the
slurry must be appropriately cooled to accommodate the
particular type of ligand. Cooling to at least 90 C or
under is necessary where the ligand is XRCN and cooling to
at least 140 C or under is necessary where the ligand is
CO. Such cooling is to be followed in the two-step
regeneration processes without quinolics where hydrogen,
carbon monoxide or syngas is employed.
With reference to Fig. 5, the aqueous acidic
cupric ion stream 20 is again fed in the first step to an
autoclave 55 to be reacted with carbon monoxide as a
reductant, not primarily as a ligand. Reduction is again
5~73
;3~5
high pressure and temperature on the order of 15 to ~0
atmospheres and from about 150 to 260 C for about 0.5 to
2 hours. A by-product gas stream comprising CO2/CO is
evolved which can be suitably utilized or disposed. The
reaction of CO with an aqueous solution of CuS04 at elevated
temperature (140~ to 150 C) and pressure has been described
as a minor side reaction by E. Peters, T. Kurnsawa, F.
Loewen and M. Nishitani in a paper entitled "A Carbonyl-
j Hydrometallurgy Method for Refining Copper" presented at the
Joint Meeting of MMIJ-AIME 1972, Tokyo, Print No. T IV c4.
The reaction is as follows:
IV 2Cu + 3CO + H'2O ~ 2CutCO) + CO2 + 2~
Some stabilized cuprous ions result as CuCO ,
along with some copper metal and cupric ions. This slurry
is allowed to cool to a temperature of at least about 140
C or under, as it passes via stream 58 to reactor 59 where,
! in the second step, it is combined with carbon monoxide as a
ligand~ Again, the stabilized cuprous ion stream 12
results. The CO ligand supply could be provided from stream
14, recycled from reactor 10 (Fig. 1) or independently.
The foregoing two-step regeneration of cuprous
ions is believed to be novel alone as well as in combination
with the other steps of the ARIS process. It is to be
understood that a combination of Figs. 4 and 5 could also be
practiced utilizing H2/CO or syngas as yet another novel
reduction step for the regeneration of cuprous ions for the
ARIS process. Inasmuch as the latter would merely be a
combination of the foregoing descriptions, a detailed dis-
cussion thereof is not deemed necessary.
Having described several of the possible regenera-
tions of Cu ions stabilized against disproportionation with
CO or C3CN and the like, it should be noted that dispro-
portionation may be desirable, to a degree, in the ARIS
process. Recognizing the ~ide variety of compositions
represented by laterite and manganese ores, it is possible
that some copper compounds can be present. As a result of
the leaching in reactor 10, these become freed as Cu2 ions
5873
2~63~S
and subsequently reduced to Cu ions in step 13. After a
period of several recyclings via stream 12, the copper ion
content would build up to an undesirable concentration.
Thus, at least one manner by which to control the
amount would be to allow a portion of the stabilized ions
Cu L to disproportionate, producing copper metal and cupric
ions approximately in equal amounts. A bleed streaml for
i instance, could be drawn off of stream 12, as is depicted in
Fig. 6. There, stream 60 will remove a predetermined amount
necessary to reduce the overall flow of copper through the
process where new copper is continuously being leached and
added. Stream 60 is fed ~to a suitable processing step 61
where the ligand L is removed either to recycle stream 14 or
¦ for other use or handling. Copper metal is removed via
stream 62 and cuprous ions are returned to stream 12 via
stream 63.
Removal of the ligand in step 61 is conventional;
for CO depressurization will result in disproportionation
while for an organic nitrile, distillation of the ligand
will destabilize the Cu ions. It is to be appreciated that
the bleed stream 60 can comprise other components as only
the cuprous ions will be affected. Alternatively, other
processing steps can be employed for excess copper removal
such as, electrolytically or cementation with iron metal.
Also, the point of copper removal is not necessarily limiting
on the practice of the present invention. One other step
could be the reduction of Cu~ to Cu, as depicted in Fig.
3, with a quinolic so long as the copper metal was not --
subsequently treated in reactor 43 to form Cu L.
Thus far, the ARIS process has been described
! wherein stabilized cuprous ions in acid medium are utilized
to leach lateritic ores and manganese sea nodules and,
wherein the cuprous ions are regenerated. More broadly, a
modification of the ARIS process is also contemplated as is
next described with reference to Fig. 7. The process is
comparable to that discussed with reference to Fig. 1 except
regeneration of the cuprous ions is not included.
5873
3~5
-23-
Crushed ore is again fed to the reactor 10 with a
supply of acid to maintain a steady pH. Stabilized cuprous
ions are provided from an independent source 60 via stream
12. If ~he ligand is CO, it can be vented from reactor 10
via stream 14 and suitably handled. The slurry from reactor
10 is fed via stream 15 to the separator 16, where nitrile
ligands are removed by stream 1~, solid tailings and the
like pass via stream 17 and the pregnant liquor passes via
stream 18 to a suitable processing step or steps~ box 19
where iron, manganese, copper, nickel and/or cobalt can be
extracted as desired. Reaction conditions such as temperature,
pressure and pH are the s'ame as set forth hereinabove for
the description of Fig. 1.
Another modification to the ARIS process exists
where ferrous ions Fe2 with the cuprous ions previously
described are employed in a leaching step, e.~., reactor 10
or other. It will first be recalled that ferrous ions
result from the leaching of laterites in reactor 10 with the
acidic cuprous ligand solution, stream 12. Ferrous ions
would be useful on a feed stream of manganese sea nodules or
a terrestrial manganese ore. An instance of the latter
could be drawn from a lateritic deposit which is most often
characterized by a vertical composition profile. Whereas
the nickeliferous Limonite is preferred for the feed to
reactor 10 with a cuprous ion reduction, the overlying
hematitic cap is often more concentrated in manganese which,
in turn, will carry a higher content of cobalt.
Inasmuch as the ferrous ions can only leach a
manganese ore, that ore is the only instance where cuprous
3~ and ferrous solutions could be combined. If, for instance,
the cuprous and ferrous solutions were employed on a
lateritic ore, the cuprous ions would selectively leach
first the manganese portion, this being preferred to cuprous
attack of the Fe2O3 phase as well as ferrou; attack of the
MnO2 phase. In a short time, the manganese phase would be
reduced, leaving no ore for the ferrous ions which, of
course, will not react with the Fe2O3 phase.
~- 5~73
24~39~S
-24-
With the foregoing as a background, reference to
Fig. 8 should now be made wherein this embodiment will be
further developed. A lateritic ore feed, Lat(a), is fed to
a reactor 70, comparable to the reactor 10, via str~am 71.
The lixiviant solution is provided via stream 72 and
includes acidic cuprous ions, properly stabilized, com-
parable to stream 12 (Fig. 1) and ferrous ions Fe2+(c) from
a separate source. The latter ions are optional and will be
employed primarily in a second, separate leaching step set
forth hereinbelow. Temperature, pressure and pH for this
step is the same as was disclosed in conjunction with the
description of Fig~ 1. A'-slurry results which is fed via
stream 73 to a separator 74. Solids or tailings exit via
stream 75 for the desired treatment, disposal or other
handling and are essentially free from Fe and Mn. Meanwhile,
the pregnant liquor, stream 76, is fed to a second leach
reactor 80. The pregnant liquor comprises Mn (a) ions and
Fe2 (a) ions from Lat(a) and Fe2 (b) and Fe2 (c) ions.
Co2+(a) and Ni2 (a) also result but have been omitted from
the drawing to simplify the latter.
Into reactor 80 is also fed, via stream 81 a
second lateritic ore, Lat~b) and/or manganese ore (c), sea
nodules or terrestrial. The leaching that will occur will
be based only upon Fe2 ions, Fe2+(a), (b) and (c), inasmuch
as no Cu ions are left over from reactor 70 or otherwise
fed into 80. Reaction conditions include the same tempera- -
ture range of 20 to 90 C, a pressure ranging from ambient
to about 0.3 MPa and the same overall pH. The resulting --
slurry passes via stream Bl to separator 82. Where the
Fe2O3 portion of laterite (b) contains desirable amounts of
Ni, the stream 83 can carry the solids, essentially
unreacted~ and tailings to the first reactor 70 where they
can be reacted with the Cu ions. If the Ni content is too
low or otherwise undesirable, stream 83 can be discarded
(not shown). The pregnant liquor stream 84 now comprises
Cu2 ions unchanged from the first redox leaching, reactor
70, Fe3 ions from the leaching reaction, Mn2 ions from
5873
~4 ....
-25-
laterites (a) and (b) as well as the m~nganese ore feed (a).
The Mn ore having been solubilized, Co2 (b) ions will now
also be present but again, do not appear in the drawing.
It will be appreciated from discussions pertaining
to the other flow diagrams, that separations of the accessed
Ni2+ and Co2+ ions could have been inserted into the process
depicted in Fig. 8 and any convenient stage such as off of
streams 7S, 83 or 84. Similarly, the Cu2 ions could have
been recycled for Cu+ regeneration, per Figs. 2~5, at any of
these streams.
Of course, variations of the process set forth in
Fig. 8 are contemplated w~thin the scope of the present
invention. Thus, while Fig. 8 depicts a second leaching
step to be utilized in conjunction with the ARIS process set
forth in Fig. 1 or the modified process set forth in Fig. 7,
i.e., no Cu ion regeneration, it is entirely possible that
the leaching in the second reactor 80 could comprise an
independent process for the selective leaching of iron oxide
containing ores which will be briefly discussed with
reference to Fig. 9.
Reactor 90 is there fed, via stream 91, an ore
having a useful content of manganese which, in turn, carries
a desirable amount of cobalt. Such ores were discussed with
reference to Fig. 8 and need not be repeated here. However,
it should be borne in mind that the process of Fig. 9 is
one that can be employed as a selective leaching of laterites - -
and the like where it is desirable to extract only the
cobalt. An acidic leach solution comprising Fe2+ ions is --
fed via stream 92 and produces a slurry, stream 93 which is
fed to a separator 94. Again, solids comprising unreacted
Fe2O3 and tailings exit via stream 95 for desired handling
and a pregnant liquor stream 96, is drawn off containing
Fe3 ions from the leaching, and solubilized ~n2 , Ni2 and
Co2 for further separation in box 98 and/or use as desired.
Although not specifically shown in combination
with Fig. 9, any Fe2O3 content could then be fed to a series
of steps as provided in Figs~ 1 or 7 wherein lateritic ore
5873
3 ~
feed is treated with Cu ions. The latter would constitute
a two-step differential leaching techni~ue whereby the
manganese and a high concentration of cobalt was first
accessed and then the iron with a high concentration of
nickel followed.
A reduction of a laterite ore, employing Fe2 ions
and inert Cu2 ions selectively to leach Co and Mn has been
provided hereinbelow as Example No. 25, reported in Table X.
General Leaching Procedure
In the several examples which are detailed herein-
below, leaching of laterites was carried out in a 500 ml
jacketed glass reactor which was provided with a stirrer~ pH
electrode, thermometer, refluxing condenser, sampling port
and a nitrogen gas sparging tube, as well as an inlet for
acid addition. The temperature in the flask was maintained
at within + 1 ~ by circulating water from a thermostated
bath into the jacket of the reactor.
A pH controller was employed to monitor and
maintain the desired constant pH during the leaching experi-
ments. A peristaltic pump, activated by the pH controller,
was used to add a (50:50 by volume) solution of H2SO4/H2O
into the reactor during the course of the redox leaching
experiments. The total amount of added acid solution was
measured at the end of each experiment.
Nitrogen gas was passed throughout the reactor at -~
a low flow rate, however, a complete exclusion of air during
these preliminar~ experiments was not attempted. Solution ~~
samples were taken at various time intervals with a 5 ml
pipette through a ground joint opening in the reactor cover
at which time air was free to diffuse into the reactor. The
stirring was stopped and the slurry allowed to settle for
one minute before the sample was withdrawn. The 5 ml sample
was talen from as close to the surface as possible to
minimize the amount of solids withdrawn. The amount of
solids taken with the sample was small and not measured~
however, the concentrations obtained and reported herein are
-~ 5873
2~3~5
somewhat lower than the actual ones due to the presence of
these small amounts of solids in the samples taken. The
samples taken were immediately "quenched" in an acidic
solution containing H2O2 as an oxidant for cuprous and
ferrous ions and brought to 100 ml total volume. Within
five minutes, part of this solution was filtered to yield
two parallel samples of about 25 ml each. These were then
labeled ~or ready identification.
All samples taken and prepared in the above manner
were analyzed by Atomic Absorption Spectroscopy. The con-
centrations of nickel, iron, cobalt, manganese, chromium,
magnesium, silicon and al~minum in the leach solution at
various sampling times were calculated from the analytical
results.
The general procedure for each series of redox
leaching experiments was as follows: The measured amount of
cupric sulfate solution, at the desired pH, was introduced
first into the reactor flask and allowed to reach the
selected operating temperature while stirring and purging
with nitrogen to displace air from the reactor, and most of
the dissolved ox~gen. The calculated amounts of copper
powder and acetonitrile were then introduced into the reator
and stirring continued until the copper powder dissolved
completely. Dissolution of copper powder yielded the
desired stabilized cuprous lixiviant for the redox leaching
Of ore.
The stirring was then stopped and the weighed
amount (50 g) of laterite was added into the cuprous solu- --
tion. This addition was completed within three minutes
after which stirring commenced. While some reaction took
place during this addition time, time zero for the redox
leaching was considered to coincide with the time when
stirring commenced.
Leaching of Laterites with Cu (CH3CN)x
Examples No. 1-9
Gasquet Mountain laterite, having the composition
reported in Table ~ hereinabove, was leached with the
5B73
~24L~i3~S
-~8-
Cu (CH3CN)x lixiviant in Examples No. 2-9 discussed herein-
below~ 50 g samples of -100 + 150 mesh dry screened
laterite was treated with the leach solution and under the
conditions found in Table II. The copper reductant solution
was made by dissolving 11.66 9 of copper metal in 382 ml of
water (unless otherwise specified) containing 0.257 moles of
CuSO4, to which 59 ml of CH3CN (unless otherwise specified)
was added. Total volume of all but one solution was 441 ml.
The initial concentration of cuprous ions, approximately
0.83M, was calculated and fixed to a 20 percent excess over
that stoichiometrically necessary to reduce all Fe(III) and
Mn(IV) to Fe2 and Mn2 , '-This concentration was employed for
Examples 2-8, half the concentration was employed for
Example No. 9 and zero for Example No. 1, a control, where
leaching was conducted in the absence of the active cuprous
ions. Concentrations of metal ions at different sampling
times ranging between three to as many as 420 minutes appear
in Table III.
5873
12; ~L~i 3 4 S
--29
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In ~ _~ O 00 ~ --
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~ ~2463~5 5873
-30-
TABLE III
Metal Ion Concentrations (~m) as a
Function of Leachlng Time for Examples 1-9
Example Rxn time
No. (min) Ni Fe Co Mn Cr
1 3 98 326 77 150 4
226 1130 87 173 14
300 366 2200 111 258 28
2 3 316 550 158 596 30
. 30 670 12850 212 584 54
: 330 956 ' 23500 224 576 112
420 972 25950 224 566 120
3 3 212 850 161 600 10
33 400 5400 212 580 20
333 782 19000 228 574 60
i 4 4 516 7700 164 - 30
: 30 830 16500 206 - 86
330 1058 25550 230 57q 160
3 452 7210 216 576 32
842 19780 238 614 96
240 1010 27910 224 584 166
6 3 220 760 200 574 4
480 7750 222 610 34
275 792 18270 228 598 90
7 3 388 4065 224 590 20
572 g648 226 586 4~
' 210 1042 .25745 230 544 150
i 8 3 306 1897 212 538 10
646 9919 230 556 48
240 934 17778 232 542 104
i 9 3 184 1376 106 292 8
300 4416 107 292 34
270 564 11910 1'~7 298 72
~ 2~63~5 5873
-31~
With reference to Table III, it will readily be
noted that a signiicant amount of the metals Ni, Fe, Co and
Mn were leached from the laterite ore with the Cu CH3CN
lixiviant as compared to Example No. l where the copper
reductant was not employed.
Decreasing the reaction temperature to 25 C,
Example No. 31 resulted in a corresponding decrease in metal
ion yields over other examples, conducted at 45 C. On the
other hand increasing the temperature to 65 C, Example No.
4, did not significantly affect the yields thereby demon-
strating that the process can be conducted at relatively low
temperatures, such as 45OrC.
The effects of pH between 1.5 and 2.5 and concen-
tration of the copper reductant solution is also demonstrated
in Table III. Generally, pH did not dramatically effect the
leaching between l.5 and 2.0, Examples No. 2 and 5, while
increasing it to 2.5, Example No. 6, did decrease the
yields. Reduction in the CH3CN addition, Example No. 7, did
not appear to effect yields, neither did dilution of the
reductant, Example No. 9 did as long as at least the
stoichiometric amount of Cu was supplied.
Analysis of the metal ion concentrations reported
in Table III also establishes that the leaching process of --
the present invention is highly selective insofar as most of
the Ni, Co, Fe and Mn is leached from the ore while most of
the Cr remains with the leach residue or tailings. It can --~
readily be noted that about three times the Ni and l0 times
the Fe content were accessed in Examples 2-9 as compared to ~~
Example l, while Cr content remained relatively low in the
pregnant liquor. In this manner, the tailings will be
certain to carry a higher weight percent of Cr than the
original ore, making recovery more economically feasible.
By selecting the right combination of temperature
pH and leaching time it is possible to opitmize the extrac-
tion of Ni and Co versus Cr. Drawing from specific examplesreported in Table III, namely Nos. 2-6, exemplary optimiza-
tion can be demonstrated as has been reported in Tables
IV and V
5873
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5873
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At a ~onstant pH of 2.0 the lowest amount of Cr
leached occurred where leaching continued for 30 minut0s.
Where greater times of 60 and 330 minutes were provided,
some increase in Ni was observed but very little increase in
Co. Temperature also had little effect of Co, but signifi-
cantly greater effect on Cr and Ni. Maintaining a steady
temperature, all three metal extractions generally increased
as pH decreased (the solution was more acid), except for Co
at 330 minutes.
A similar comparison can be made by examining the
concentration ratios of Ni/Cr and Co/Cr at various sampling
times provided in Table ~..
~ . 5873
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5873
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The highest Ni/Cr concentration occurred at the
lowest temperature and pH of 2.0 and decreased as the tem-
perature rose. Increasing the pH, Example No. 6, improved
the ratio at 45 C. The best Co/Cr concentrations were also
obtained at the lowest temperature or highest pH.
A measurement of acid addition (H2SO4) versus
metal ion solubilization was also examined and is reported
in Table VI for a separate example, No. lOo The condi~ions
for Example No. 10 were those employed for Example No. 2,
but 50 9 of -100 + 150 mesh wet screened laterite was
leached rather than dry screened.
TABLE VI
Acid Addition During Leach Reaction
Time Conc. H2SO4
Ex. No. (min) (ppm) Ni Fe Co Mn tg)
10 3 444 3000 294 7622.7g
30 642 12060 298 76619.77
2090 712 15640 290 74~24.86
Separate analyses of the metal extraction data
revealed that the addition of acid beyond a certain point, --
e.g., 20 9, would not increase the extraction of Ni but
would contribute to further dissolution of Fe and Cr.
In order to determine the efficiency of the ---
present process, more specifically when the Cu CH3CN lixi-
viant is employed, a separate evaluation was conducted --
employing a two stage leaching.
A 50 gram sample of the laterite ore, -100 + 150
mesh dry screened, Example No. 11, was leached with the
solution and under the conditions reported for Example No. 4
hereinabove for a total of 330 minutes. This solution was
filtered and the leach residue collectc-d. This residue was
then subjected to a second leaching step, identical to the
first for 90 minutes after which the remaining leach residue
was filtered and washed. This second residue was then
5873
;3~5
-36-
digested with aqua regia to determine metal values not
leached.
The laterite feed material was similarIy digested
and analyzed following which a mass balance was then con-
S ducted and the results were used to calculate the percentrecovery, or eventually solubilization for Ni, Co, Fe, Mn
and Cr. The values were as follows: Ni 95.4%; Co 98.3%; Fe
97.2%; Mn 98.4%; and, Cr about 10 to 20%.
Leaching of Manganese ore with Cu (CH3CN)
Having established the usefullness of the Cu (CH3CN)
lixiviant with laterite o~e, further evaluations were con-
ducted to demonstrate the ability of this material to reduce
manganese sea nodules.
The reactor employed was similar to the one dis-
cussed hereinabove in conjunction with the laterite leaching
examplec, except that it had a 500 ml capacity and improved,
high speed stirrers. Pacific ocean manganese nodulesl -150
~ 200 mesh dry screened were employed and three exemplary
! 20 experiments were conducted. Example No. 12 was a control or
blank where no Cu (CH3CN) was employed. Examples No. 13 and
14 represent practice of the present invention.
! Example No. 12
I
44.2 g of CuSO4 were dissolved in 225 ml of H2O and
the pH was adjusted to 2.0 by the addition of the same ---
H2SO4:H2O mixture (50:50 vol). The solution was added to
the glass reactor under N2 purge and maintained at a con- --
stant 45~ C. Then, 25 9 of the manganese nodule was added
with 100 ml H2O. Stirring commenced at time zero and acid
was provided on demand to maintain the pH at 2Ø 5 ml
i samples of solution were withdrawn at various times, diluted
to 100 ml with H2O/acid, filtered and analyzed by atomic
absorption. After 90 minutes, the solution was filtered
and 290 ml thereof were collected. Metal ion concentrations
appear in Table VII with values for Examples No. 13 and 14.
~f4~3~ 5873
Example No. 13
Utilizing the same reactor as for Example 12~ 24 9
of CuS04 were dissolved in 250 ml of H20 and the pH was
adjusted to 2Ø The solution and 8.0 9 of Cu metal were
added to the reactor under N2 purge. The reactants were
~ vigorously stirred at 45 C under refluxing conditions.
¦ Next, was added 48 ml of CH3CN with acid on demand to main-
tain pH and generate the cuprous lixiviant. Finally, 25.0 9
of manganese nodules was added with 50 ml of H20 at time
~-ero. 5 ml solution samples were again withdrawn at various
. times, diluted to 100 ml with H20/acid, filtered and
; analyzed. After 90 minutes, 415 ml of filtered solution
remained.
~ 15 Example No. 14
¦ This procedure was conducted as the previous one
except the addition of 25.0 9 of nodules was with 25 ml of
H20. Supply of H2S04:H20 was not fast enough to maintain pH
which did rise to 3.8 upon addition of the sea nodules. It
was returned to 2.0 after 15 minutes although by then the
reaction was substantially complete.
~ .
~- - 5873
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~38-
TABLE VII
Redox Leaching of Manganese Sea Nodules
with Cuprous Aeetonitrile
Example No. 12 13 14
Time
Element(min)
Mn 3 0.192 4.64 10.78
g/l 10 0.230 - , 14.64
- 10 15 - 10.5
0.240 - 15.34
~0.258 - 15.36
0.264 10.68 15.32
Fe 3 0.088 2.42 6.18
9/1 10 0.119 - 9.94
- 5.98
0.131 - 10.62
0 ~ 142 ~ 10 r 96
0.135 6.24 11.02
Ni 3 6.0 177.6 386
ppm 10 10.6 - 544
- 412.0
19.2 - 570 -
29.4 - 566
37.0 428.0 578
Co 3 1.2 29.6 64 - -
ppm 10 1.4 - 80
~ 59.4
1.4 - 81
1.8 - 78
2.2 60.0 79
Co 3 1.2 29.6 64
ppm 10 1.4 - 80
- 59.4
1.4 - ~1
1.8 - 78
2.2 60.0 79
~4~3L~5 5873
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The leach residue from Example No. 14 was digested
in aqua regia and the solution analyzed by atomic absorp-
tion~ The Mn nodule feed material was also subjected to
this digestion and analysis. Mass balance calculations
showed the following percent solubilizations by weight: Mn
99.9; Fe 94.3; Ni 99.4; and, Co 99.6.
Leaching of Laterite with
Cu(C0) Acidic Solution
Two experiments were conducted and evaluated
utilizing Cu(C0) for the reduction of a laterite ore as
follows: '`
Example No. 15
Into a one liter autoclave was charged 39.5 g
CuS04, 5.24 9 of copper powder and 550 ml of water. The
mixture was purged with C0 to remove air and the pH was
adjusted to 1.5 using H2S04/H20 (50:50 vol). The reaction
was stirred at 45 C under a C0 pressure of 175 psig (1.21
MPa) for four hours in order to insure complete dissolution
of the copper metal.
Next, 500 ml of the cuprous solution formed in the
first autoclave (A) was transferred to a two liter autoclave --
(B) by pressure differential under C0. Autoclave B con-
tained 25 9 Gasquet mountain laterite, -270 mesh wet
screened, at 45 C and 75 psig (0.52 MPa) C0. When the - -
transfer of solution from autoclave A to B was completed,
stirring in B commenced as did leaching of the laterite and --
time zero was established. Total C0 pressure during
leaching was maintained at 1.21 MPa and the acid/water
solution was added on demand to maintain pH at 1.5. The pH
probe monitoring device failed after 30 minutes and there-
fore acid addition was discontinued. At the end of the
leaching, the contents of B were filtered. Solids content
was 11.~ 9 wet; filtra~e collected was 500 ml.
-- 5873
463~L5
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Example No. 16
The procedure followed was identical to that for
Example No. 15 except that 20 9 of Gasquet laterite was
leached in Autoclave ~. The pH probe functioned properly
and total acid/water addition on demand, 50:50 volume, was
11 9. The pH drifted from 105 to 1. over the total leaching
time.
Metal ion concentrations were measured by with-
drawing 5 ml solution samples from Br Each sample was
quenched in H2O (acidic) containing a small amount of
hydrogen peroxide and then diluted to 100 ml. Each solu-
tion was analyzed after f'iltration, by atomic absorption
spectroscopy. The metal ion concentrations for Fe, Ni, Mn
and Co at various times in minutes from time zero were
measured and have been reported in Table VIII. Concen-
trations for Fe were 9/1 while for the other four metals ppm
has been indicated.
TABLE VIII
Metal Ion Concentrations Following
Laterite Leaching with Cu(CO)
Time Fe Ni Mn Co Cr --
Ex. No.(min) g/l ppm
3 5.45 134 103 33 30
9.52 251 164 57 56 --~
12.70 315 182 62 74
19.14 364 234 79109
120 20.70 400 2~2 80117
16 3 1.12 67 131 45 11
1.84 101 175 64 13
4.78 175 264 92 22
6.46 214 192 65 31
8.76 236 1~0 64 40
120 11.18 314 212 73 ~9
k~ 46 3 ~ 5 5873
-41-
Again, it can be observed that the leaching process
produced large amounts of Fe and Ni, apparently less Mn
and Co but nevertheless high values because laterites are
low in these values and, little Cr.
Reduction of Cu to Cu (CO)
j As has been developed hereinabove, the process of
the present invention employs cuprous solutions to leach
laterites, manganese sea nodules and similar ores. These
10 can be generated by any suitable means including those
disclosed herein. At least one novel and preferred method
for preparing the cuprous'`reductant is set forth herein and
f it involves the use of a quinone Q, as disclosed herein-
; above.
General Procedure
In the examples which follow, the given anthra-
quinone AQ was first dissolved in a solvent mixture of polar
and non-polar organic solvents. The ratio of each is
20 optimized for the maximum solubility of both the anthraquinone
and its corresponding anthraquinol and thus, neither the
solvents nor the specific amounts should be construed as
limiting. -
The organic solvent mixture was introduced into a
25 first autoclave followed by the addition of a hydrogenation
catalyst such as 5% Pd on A12O3. Air was displaced with an --
inert gas Ar, although He, N2 and the like could be sub-
stituted. Pressure was increased to 125 psi (0.86 MPa) with ~~
stirring and heating to 50 C. Hydrogen gas was introduced
30 to a total pressure of 175 psi (1.21 MPa) and was maintained
¦ by periodic addition.
The desired volume of reduced organic material was
transferred from ~he first autoclave to a second under
pressure. The liq id organic was transferred from the first
35 autoclave through a dip tube equipped with a filtering
element in order to retain the hydrogenation catalyst. The
second autoclave contained an aqueous acidic cupric sulfate
5873
L 6 3 ~ S
--42--
solution at a given pH, temperature, copper concentration
and volume and under a CO pre ssure. Time zero for the
reaction commenced with stirring of the transferred organic
and aqueous solution with CO gas.
5 cc samples of aqueous phase were taken at time
intervals indicated in Table IX. These were then oxidized
with an acidic FeC13 (lM) 25 ml solution which was titrated
with a cerric ammonium sulfate solution to determine ferrous
ion. From this, the concentration of cuprous (generated)
versus time in the autoclave ~as calculated and the total
copper concentration was determined by atomic absorption
spectroscopy.
Example No. 17
15 Organic (Autoclave 1) 60% vol xylene
40% vol 2-ethyl-1-hexanol
49 g/l 2-ethyl anthraquinone
550 ml of organic reduced with H2 over
5% Pd (1 g) on A12O3 in autoclave 1 at
50 C
472 ml of organic transferred to autoclave 2
Aqueous (~utoclave 2)
125 ml CuSO4 solution, [Cu] = 75.0 g/l
pH = 2.0
T = 50 C
125 psig CO (0.B6 MPa)
After transfer of the organic, the total pressure was increased
to 225 psig (1.55 MPa) with CO and maintained. --
Example No. 18
Organic Same as for No. 17, except 500 ml transferred
to autoclave 20
Aqueous Same as for No. 17, except CO pressure was
maintained at 150 psig (1.04 MPa).
- 5873
i345
Example No. 19
Organic (Autoclave 1) 3000 ml xylene
1000 ml isobutyl-heptyl-ketone
220 g 2-t-butyl-anthraquinone
5S0 ml of organic reduced as in Example No. 17
485 ml of organic transferred to autoclave 2
Aqueous (Autoclave 2)
250 ml CuSO4 solution, ICu] = 48.6 g/l
pH = 2.0
T = 50 C
50 psig CO (0.35 MPa)
After transfer of the org~anic, total pressure was increased
to 150 psig (1.04 MPa) with CO.
Example No. 20
Organic Same as for No. 19, except 495 ml transferred
to autoclave 2.
Aqueous Same as for No . 19, except 167 ml volume
of CUSO4.
Example No. 21
Organic Same as for No. 19, except 495 ml transferred
to autoclave 2. --
Aqueous Same as for No. 19, except 125 ml volume
of CuSO4.
Example No. 22
Organic Same as for No. 20, except 495 ml transferred
to autoclave 2.0 Agueous Same as for No. 19
Total CO pressure, 225 psig (1.55 MPa).
Exa-mple No. 23
Organic Same as for No. 19 except 500 ml transferred
to autoclave 2.
Aqueous Same as for No. 19 except 167 ml volume of
CuSO4.
Total CO pressure, 225 psig (1.55 MPa).
^~ *~ ~4~3~ 5873
-44-
At the end of the reduction, the aqueous solution was color-
less indicating almost total reduction to Cu .
TABLE IX
Cu+ Concentration (9/13 versus time
Example Nos.
Time
(min) 17 18 19 20 21 22 23
2 11.3 10.73.8 8.2 1S.37.3 20.3
26.4 27.09.515.1 30.819.4 34.6
39.4 42.917.8~20.8 49.935.4 50.8
51.8 62.827.922.1 49.738.7 50.2
As can be seen from Table IX, the highest cuprous
concentrations were observed for Examples 17, 18, 21 and 23
with acceptable concentrations occurring ater only 20
minutes.
Selective leaching of Co, Ni and Mn from
Laterite with Fe /Cu acid solution
As stated hereinabove, the pregnant liquor from
the first step of the ARIS process for the leaching of
laterites contains reduced iron Fe2 and oxidized copper
Cu2 . This material could be employed to reduce manganese
from a fresh supply of ore which also results in the -
dissolution of cobalt. In the work which is discussed next,
two experiments were conducted to demonstrate the use of --
this reductant solution. The first, Example No. 24 con-
stitutes a control or blank with Cu2 and H2SO but no
Fe2 . The second example, No. 25, employed Cu~ , H2SO4 and
Ee2 which was added to simulate the pregnant liquor from
the first step of the ARIS process.
The following ingredients were dissolved, stirred
and heated in a 500 ml jacketed glass reactor at 45 C with
the necessary addition of H2SO4 to maintain a pH of 2Ø
Example ~o. 24: 341 ml H2O plus 70.3 9 CUSO4; Example No.
-
~ 63~S 5873
25: 341 ml H2O plus 70.3 9 CuSO4 plus 61.3 9 FeSO4.
At time zero, 50 g of Gasquet laterite, -270 mesh
wet screened plus 100 ml of H2O were added to each reactor.
~amples were taken and analyzed as previously described and
! 5have been reported in Table X all concentrations being ppm.
TABLE X
Leaching with Fe2 /Cu2 Acid Solutions
!
Time Example No.
Element (min) 24 25
Co 3 '~ 12.40 154.00
13.60 144.00
17.60 156.00
120 22.20 146.00
Mn 3 37.20 486.00
40.00 482.00
47.40 498.00
120 58.00 492.00
Ni 3 50.40 188.0
66.00 220.00
99 00 248.00
120 133 80 260.00
Clearly, the Fe2 ions accessed greater concen-
trations of Co, Mn and Ni than occurred where they were not
employed.
! In conclusion, it should be apparent that those ~--
¦ processes disclosed herein for redox leaching are highly
! 30 effective in selectively extracting useful metals such as
nickel and cobalt, as well as iron and manganese, and copper
! when present, from lateritic ores and manganese ores, both
terrestrial and sea nodules. Not only are these metals
extracted in nearly guantitative yields but the processes
operate at low temperature and pressures and without
incurring the expense of costly reagents or reagents that
cannot be regenerated inexpensively~
5873
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-46-
Insofar as the latter regeneration i6 considered,
those processes that have been disclosed herein can be
characterized by fast, clean, relatively inexpensive steps
utilizing only H2, CO or syngas and without elaborate
processing or producing deleterious by-products. It should
also be evident that, if desired, another useful feature of
the present invention is that it provides processes whereby
chromium and certain precious metals, contained in the ores
treated can now be extracted inasmuch as the various
processes do not access these metals to any significant
extent, in effect, concentrating the content in the solid
ore residue from whence t~o or three times the original
percentage per unit weight is provided.
Thus, it should be apparent to those skilled in
the art that the ARI~ processes and those modifications and
adjuncts set forth herein are operable on a variety of ore
feeds, in various combinations, described or otherwise
disclosed, and within various processing parameters. The
present processes should not be limited by known methods of
final separations of the metal ions extracted in the
pregnant liquor, i.e., Fe , Mn , Ni and Co or by their
point of removal and these can readily be designed into an
overall system in consideration of existing equipment and/or --
the by-products desired by the operator.
Furthermore, it is to be understood that all of
the variables, those disclosed as well as those falling --
within the existing skill in the art, fall within the scope
j of the claimed invention and that the subject invention is --
in no way limited by the examples and respective tables set
forth herein. These have been provided merely to provide a
demonstration of operability and, therefore, the selection
of ores, reactants, processing steps and parameters and the
like can readily be determined without departing from the
spirit of the invention herein disclosed and described.
Moreover, the scope of the invention shall include all
modifications and variations that fall within the scope of
- the attached claims.
