Note: Descriptions are shown in the official language in which they were submitted.
~88178
IMPROVED CARRIER PARTICLE FOR T~E
FROTH FLOTATION OF FINE ORES
The invention relates to the beneficiation of
ores by froth flotation.
This invention is a froth flotation process
for beneficiating finely sized ore values from a finely
sized ore pulp comprising floating the finely sized ore
pulp in a frothing aqueous medium comprising a collector,
a frother, and carrier particles for beneficiating the
finely sized ore values wherein the carrier particles
selectively float the finely sized ore values.
The carrier particles of this invention
should have a particle size and a density which are
suitable for selectively beneficiating the finely sized
ore particles by froth flotation. The carrier particles
of the invention also have a surface treated with a
condensation product, or acid derivative of a condensation
product, of an alkanolamine with a fatty acid, a fatty
~g
30,277-F -1-
~81~
-2-
acid ester, a dibasic fatty acid or a tribasic fatty
acid, in an amount sufficient to render the carrier
particle hydrophobic to float in the frothing aqueous
medium and to act as a carrier for the finely sized
ore particles.
Surprisingly, the carrier particles that have
been separated from the beneficiated ore can be reused
- for flotation without any further processing and treatment.
This is a significant advantage over prior art processes
wherein the carriers require further processing before
reuse.
Froth flotation is a widely practiced process
for separating multicomponent ores into their components.
The process is amenable to a large variety of ores and
provides in many instances, a highly economical and
efficacious method for concentrating components of
ores.
There are, however, several limitations to
froth flotation processes. One of the most serious
drawbacks to these processes is that a very fine sized
ore feed, such as a feed comprising particles passable
through a 74 micrometer screen, and particularly those
of -10 micrometers or finer, are not effectively concen-
trated by froth flotation. Such very fine particles or
slimes may be naturally occurring constituents of ores
or may be artificially produced during the grinding ~f
the ore to a suitable size for mineral liberation. It
is well-known to those skilled in the art that certain
materials will not float in a froth flotation process
when ground to an exceedingly fine size, although they
will float under the same conditions when provided in
coarser grain size.
30,277-F -2-
lX88178
At any rate, those who have heretofore attempted
to concentrate components of various finely sized ores
by froth flotation have met with little success.
Accordingly, they have advocated desliming prior to
flotation, when possible, although such practice adds
to the processing costs and loss of mineral values.
Further, it is general practice to desist, when possible,
from grinding certain ores to a degree at which finely
sized ores or slimes are artificially produced.
In many instances, finely sized ores or
slimes cannot be avoided and removed, when present, for
economic or practical reasons. For example, kaolin
clay is a naturally slimed mineral, consisting predomi-
nantly of particles of a size of 2-microns or finer.
This clay is mechanically associated with very finely
divided color body impurities which detract from the
value and utility of the clay in many applications.
Prior art efforts to beneficiate the clay by floating
the color body impurities have met with mediocre success
at best unless the clay feed was pre-fractionated to
reduce the quantity of fines. Certain relatively
coarse grained ores also have defied effective froth
flotation since they are not readily reduced to suit-
able flotation feed size without provision of fines
when they are ground to overcome interlocking between
dissimilar mineral genera to permit their flotation.
As examples of ores which become slimed when ground for
flotation feed may be cited cassiterite ores, taconite
ores, magnesite-brucite ores and uraninite ores (from
which concentration of uranium values are desired).
Other examples are well-known to those skilled in the
art. The technical literature is replete with reports
of poor results in beneficiating such slimed ores by
froth flotation without prefractionation or desliming.
30,277-F -3-
~ ~ 84a178
One method of beneficiation by froth flotation of fine ore
pulps is by the use of carrier particles. Greene et al.,
USP 2,990,958, teach a process for the froth flotation of very
finely divided multicomponent mineral masses in which the finely
divided or slimed feed is conditioned with (1) a reagent capable of
selectively oiling a desired component of the feed for entry into
the froth during the concentration step, and (2) a particulate
auxiliary mineral which is collector-coated (oiled) in a manner
such that it is also capable of entry into the froth during the
concentration step, thereby enhancing or promoting the flotation of
the selectively oiled fraction of the feed. The ore feed, thus
conditioned and in the form of an aqueous pulp is subjected to
froth flotation, thereby producing (1) a froth product which is a
concentrate of the oiled water-repellent component of the feed in
intimate association with the collector-coated water-repellent
auxiliary mineral particles and (2) a machine discharge product
which is the component of the feed which has not been selectively
oiled and is thus water-wettable.
It is taught that any ore which may be appropriately con-
ditioned for flotation in the presence of a reagentized feed pulp
can be used as a carrier particle. Examples given include calcite,
bartyes, kyanite, silica sand, anatose and fluorspar. The size of
the particles used are from 1410 microns to 5 microns or finer,
preferably finer than about 44.5 microns. The auxiliary mineral is
coated with an oriented hydrophobic surface coating, of a character
such that the auxiliary mineral will be floatable in the presence
~288178
-- 5
of the particular reagentized feed pulp which is being benefici-
ated. The reagent used as a collector for the ore can be used to
coat the auxiliary mineral. The examples show the use of a soap
prepared from tall oil fatty acids and a suitable base as the
coating agent.
It is further taught that the optimum amount of the auxil-
iary mineral may also vary within a wide range. The minimum amount
based on the fraction of the feed to be floated is ordinarily at
least an equal amount or more by weight. Further, the amount of
auxiliary mineral may be equal or double or more by weight of the
total feed. After flotation, the auxiliary mineral and component
of the feed floated can be separated, and the auxiliary mineral can
be reused for flotation after re-oiling.
Duke et al., USP 3,425,546, teach a process for recycling
the carrier described in USP 2,990,958. In the process, the non-
oiled slimes in the froth are removed from the froth. Preferably
this is accomplished by hydraulic sedimentation whereby the non-
oiled slime is removed as an aqueous suspension from the oiled
constituents which form a sediment. The resulting "washed" froth,
which includes oiled carrier particles and an oiled constituent of
the feed is filtered and dried at a temperature and for a time
sufficient to place the froth residuum in a solid, pulverulent
condition but insufficient to decompose or destroy either the oil-
ing reagents or the carrier ore. The dried froth is pulverized to
a finely divided state, producing a product suitable for recycling.
A portion of the recycle product is employed in combination with
~288~8
- 5a -
fresh makeup carrier and oiling reagents (for collector-coating
the makeup carrier and recycle product) to condition a new charge
of finely divided ore pulp for carrier froth flotation. It is
taught that unless the froth is dried
1288178
to pulverulent, substantially bone-dry condition, the
recycled product produces poor flotation results.
Clark et al., USP 3,868,318, teach that fine
particles of a mineral are separated from a mixture of
fine particles, by contacting the fine mineral particles
with solid bodies (carrier particles) having a mean
diameter of at least 10 micFons so that the fine parti~les
of the particular mineral are preferentially adsorbed
on the surface of the solid bodies, and separating the
solid bodies holding the adsorbed fine particles of the
mineral from the remainder of the particles. The solid
bodies are preferably coarse particles of a granular
form or short fibers having a length of from 1 to 2
millimeters. The solid bodies can be treated with
surface-active reagents such as a long-chain amine,
preferably having at least 8 carbon atoms, or a long-
chain polymeric flocculant (number average molecular
weight of at least 100,000), for example a polyacryl-
amide or a polyacrylate salt. The above separation can
be done in:a froth flotation process.
Unfortunately, none of the above-described
references teach a process wherein valuable finely
sized ore can be beneficiated by froth flotation in an
efficient and economical manner. There is a need for a
carrier particle to aid in the beneficiation of finely
sized ores by froth flotation which can be recycled
without further treatment. There is further needed
such a carrier particle which can be used in relatively
small amounts, and which can reduce the amount of the
frother or collector needed for froth flotation. A
carrier particle of a size which can easily be separated
from the finely divided ore which has been beneficiated
30,277-F -6-
1~88178
and which does not contribute to the problem of an
excessive and stable froth, is desirable.
More particularly, the present invention
provides a froth flotation process for beneficiating
finely sized metal or phosphate particles from a finely
sized mineral ore pulp, comprising the steps of floating
the mineral ore pulp in a frothing aqueous medium
comprising a collector for the metal or phosphate
particles, a frother, and carrier particles, wherein the
carrier particles are present in an amount for
beneficiating the metal or phosphate effective particles
by flotation, said carrier particles being selected from
glass; calcite, magnetite, quartz; taconite; transition
metals; transition metal oxides and hydrates thereof;
group IIIA metals, metal oxides and hydrates thereof;
group IVA metals, metal oxides and hydrates thereof;
metal carbonates, sulfides; or silicates; wherein said
carrier particles are adapted for selectively floating
the metal or phosphate particles and have a particle
size of from 10 to 300 microns and a density which is
suitable for selectively beneficiating the metal or
phosphate particles by froth flotation, said carrier
particles having a surface treated with a condensation
product, or acid derivative of a condensation product,
of an alkanolamine with a fatty acid, a fatty acid
ester, a dibasic fatty acid or a tribasic fatty acid in
an amount sufficient to render the carrier particles
sufficiently hydrophobic to float in the frothing
aqueous medium amd to act as a carrier for the metal or
phosphate particles under conditions such that the metal
or phosphate particles and the carrier particles are
recovered in the froth, wherein the surface of the
carrier particles is treated with the condensation
30,277-F -7-
~ 288178
-7a-
product prior to contacting the carrier particles with
the frothing aqueous medium, with the proviso that the
condenqation product with which the carrier particleq is
treated i~ a different compound than the compound used
as the collector for the metal or phosphate particles.
There are several advantages to the invention
claimed and deqcribed herein. A carrier particle size
has now been discovered which exhibits the maximum rate
of flotation when hydrophobized, that is, when treated
with the condenqate. This discovery allows the use of a
surprisingly lower concentration of carrier particles
for a particular separation than in the prior art
processe3. A reduction of the concentration of the
carrier particles minimizes the loss in the grade of the
recoverable ore valueQ due to quch use.
In this invention, a qmall amount of condensate
is needed to treat the carrier particle. The
30,277-F -7a-
.~
~288178
--8--
invention resides in the discovery'of an amount which
allows maximum flotation of the carrier particles.
Also surprising is that this invention allows the use
of coarser carrier particles than used in the prior art
processes. The use of such particles eliminates exces-
sive and stable froth pFoblems commonly attributed to
the presence of fine particles in ore pulps. Further,
the use of-such carrier pa-rticles reduces the level of
frother needed, which also aids in reducing the amount
and stability of the froth.
The alkanolamines useful in this process
include those represented by the formula
N-R
/
R
wherein
R is independently in each occurrence a
hydroxyalkyl group or inertly-substituted hydroxy-
alkyl group having from 2 to 5 carbon atoms with
the proviso that the hydroxy group is not on the
carbon adjacent to the nitrogen, a hydrogen, an
alkyl group having fro,m 1 to 4 carbon atoms, a
alkenyl group having from 1 to 4 carbon atoms, or
a monovalent group corresponding to the formula
30,277-F -8-
1288178
g
~ -(CH2)y~
R3
or II
R4 R5
[R -(N-CH2-CH)b-]
with the further proviso that at least one of the
R's must be a hydroxyalkyl of the type defined
above,
wherein
y is an integer of 2 to 3;
R2 and R3 are independently a hydroxyalkyl
. gr~up or an inertly substituted hydroxyalkyl group
having from 2 to 5 carbon atoms with the proviso
that the hydroxy group is not on the carbon adjacent
to the nitrogen, hydrogen, an alkyl or an alkenyl
group having from 1 to 4 carbon atoms;
R4 is independently hydrogen, alkyl or hydroxy-
alkyl having from 1 to 4 carbon atoms;
R is independèntly hydrogen, hydroxy or
methyl; and
b is an integer of greater than 1 with the
proviso that b is of a value such that the molec-
ular weight of the alkanolamine is less than about
1500
30,277-F -9-
~2881~8
--10--
In one preferred embodiment, the hydroxyalkyl
group of R is ~-hydroxyethyl. In another preferred embod-
iment, two R's are ~-hydroxyethyl and the third R is hydro-
gen. In still another preferred embodiment, one R is
5 ~-hydroxyethyl, a second is ~-hydroXyethyl or hydrogen
and the third is a univalent group corresponding to the
formula
~ -(CH2)2-
R3
wherein R2 and R3 are separately ~-hydroxyethyl or hydro-
gen with the proviso that either R2 is ~-hydroxyethyl or
the other two of the R's are ~-hydroxyethyl.
In another preferred embodiment, b is
from 2 to 5, inclusive, and R4 is preferably hydroxy-
ethyl or hydrogen and R5 is preferably hydrogen or methyl.
The alkanolamine utilized as a component of
the condensation product in the practice of this inven-
tion is an unsubstituted or N-alkyl-substituted monoetha-
nolamine; diethanolamine; triethanolamine; ~-hydroxyethyl-
ethylenediamine; N,N'-di(~-hydroxyethyl)ethylenediamine;
N,N-di(~-hydroxyethyl)ethylenediamine; N,N,N'-tri(~-hydroxy-
ethyl)ethylenediamine; N,N,N',N'-tetra(~-hydroxyethyl)eth-
ylenediamine; and like compounds in which the ethylene moi-
ety is replaced by a propylene group and/or the ~-hydroxy-
ethyl group is replaced by a hydroxyalkyl group having from
3 to 5 carbon atoms wherein the hydroxy group is not on the
carbon adjacent to the nitrogen. For reasons of economics,
30,277-F -10-
~Z88178
--11--
the hydroxyalkyl group is desirably a hydroxyethyl, l-meth-
yl(hydroxyethyl) or l-ethyl(hydroxyethyl) group. However,
the above-identified unsubstituted alkanolamines bearing
only hydroxyethyl and ethylene moieties are preferred. Di-
ethanolamine, triethanolamine and di-, tri- or tetra(hy-
droxyethyl)ethylenediamine are especially preferred alka-
nolamines, with diethanolamine being the most preferred.
The alkanolamine can be a single compound or a mixture of
operable alkanolamines, with the latter being preferred
I0 for economic reasons. These alkanolamines are available
commercially or can be readily prepared by the reactions
of alkylene oxides with ammonia or an alkylene diamine in
a manner known to the art.
The fatty acid condensed with the alkanol-
amine can operably be a fatty acid having a saturated
or unsaturated aliphatic group. The fatty acid can suit-
ably bear hydroxyl substituents on its alkyl portion, but
such substitution does not impart any substantial advan-
tage. Fatty acids such as oleic, lauric, linoleic, pal-
mitic, stearic, myristic, mixtures thereof and other likefatty acids are preferred. The esters corresponding to
the fatty acids, such as glycerides, are also operable,
but less preferred. In some embodiments the fatty acid
may be substituted with a second or third carboxylic acid
group, making the fatty acid a dibasic or tribasic acid.
For reasons of economy, it is preferred to use crude mix-
tures of fatty acids and rosin acids, lignin and unsaponi-
fiable material, such as tall oil, coconut oil, p~lm oil,
~,?alm kernel oil, cottonseed oil, linseed oil, olive oil,
peanut oil, fish oil and the like. Tall oil and tall oil
heads are especially preferred mixtures of fatty acids.
Tall oil and tall oil heads are well-known compositions
30,277-F -ll-
1288178
described in the Kirk-Othmer, Encyclopedia of Chemical
TechnoloqY, 2nd Ed., Vol. 19, pp. 614-629 (1969).
The fatty acid or corxesponding ester and the
alkanolamine can be readily reacted by bringing them
together with heating until the desired degree of
condensation has taken place as indicated by the water
distilled overhead or- infr~red spectrophotometric
analysis of the condensation product. Generally, a
temperature of from 120C to 250C is operable. The
reaction is termed a condensation herein to distinguish
it from the formation of the ammonium salt of the acid
at lower temperatures. Dependent on the alkanolamine,
the condensation product may be an ester, an amide or
both. Although it is desirable that the condensation
reaction is substantially complete to make most efficient
use of the reactants, the condensation product is
operable ~n the presence of a substantial amount of
unreacted fatty acid and the uncondensed alkanolammonium
salt of the acid.
Preferably, the molar ratio of fatty acid or
fatty acid ester to alkanolamine in the condensation
product is between 0.5:1 and 4.0:1. More preferably,
the ratio is between 1:1 and 2.5:1. Most preferably,
the ratio is between 1:1 and 2:1.
.. . .
The carrier particle may be any solid parti-
cle of a size and density suitable for beneficiation of
fine minerals by froth flotation, and which may be
appropriately conditioned for flotation in the presence
of a finely sized mineral ore pulp where the ore pulp
has been conditioned for flotation. Desirabie sizes
for carrier particles are from 10 to 300 microns,
30,277-F -12-
.288178
--13--
preferably from 10 to 150 microns. The present invention
resides in:the discovery that the carrier particle size
which demonstrates the maximum rate of flotation when
hydrophobized is between from 10 to 150 microns. It is
desirable that the carrier particles have a density
greater than 1, preferably greater than 1.5. Desirable
carrier particles must also be of the type which can be
coated with the condensates described above. Examples
- of carrier particles include: glass, calcite; magnetite;
quartz; taconite; transition metals; transition metal
oxides and hydrates thereof; group IIIA metals, metal
oxides and hydrates thereof; group IVA metals, oxides,
metal oxides and hydrates thereof; metal carbonates;
sulfides; silicates; and the metals being beneficiated.
Preferred carrier particles are transition metal oxides
and thereof; group IIIA metal oxides and hydrates
thereof; and group IVA oxides, metal oxides and hydrates
thereof. A most preferred carrier particle is alumina
trihydrate.
For the carrier particles to aid in the
flotation of mineral values in fine ores, they must be
treated with the proper amount of the condensates. If
too little is used, the carrier particles will not
float under flotation conditions because the particles
become too hydrophilic and do not adhere to air bubbles.
If too much is used, the carrier particles become so
hydrophobic that they agglomerate and will not effectively
act as ca~rie~ particles. Desirable condensate amounts
are from ~ ~ rcent by weight of the carrier
particle, preferably from 0.02 to 0.1 percent by weight
of the carrier particle. The amount which is best
suited for a particular flotation depends upon the type
and size of the carrier particle, the mineral values to
be beneficiated-and the size of the particles of the
ore pulp.
30,277-F -13-
~288178
-14-
.
The carrier particles are treated in a manner
such that the condensates described above are adsorbed
onto the carrier particles.
In one embodiment, the carrier particles are
coated with the condensates. In this embodiment, the
carrier surface adsorbs a portion of the condensate, so
that the condensate will remain on the s~rface. The
- condensates are placed on the carrier particle in the
> following manner. A slurry of the carrier particles in
water is prepared. The condensate is then added,
either directly or as an aqueous dispersion if not
water-soluble. The slurry is then stirred vigorously
to distribute the surface-treating reagent evenly over
the surfaces of the carrier particles for a period of
time of from 5 to 15 minutes.
The slurry is then filtered and centrifuged,
and dried for a period of time of from 2 to 6 hours, or
as appropriate at a temperature of from 80C to 110C.
The carrier particles may be optionally washed with
water prior to drying.
In another embodiment, where the fatty acids
or fatty acid esters used are substituted with a second
carboxylic acid group, the condensates can be cross-linked
on the surface of the carrier particle. In this embodiment
the carrier particles are slurried in water. To the
slurry is added the alkanolamine-carboxylic acid salt.
The slurry is then stirred vigorously for a period of
from 5 to 15 minutes. The carrier particles upon which
the alkanolamine-carboxylic acid salt has been adsorbed
30- are then removed from the water by known methods such
as filtering and centrifuging. The dried carrier particles
30,277-F -14-
~288178
--15--
are then heated to a temperature of from 120C to 200C
for a period of from 2 to ~ hours or for such a period
as is needed to complete the condensation reaction to
condense the alkanolaminecarboxylic acid salt on the
surface of the carrier. Condensation product herein
refers to a product of the reaction wherein a molecule
of an alkanolamine and a carboxylic acid react together
while liberating a molecule of water. By using fatty
acids substituted with additional carboxylic acids, the
condensation products will be cross-linked on the
carrier particle.
By treating the carrier particles with the
condensate described above, the carrier particles
become hydrophobic and floatable. Further, the finely
sized mineral values which have been treated with
collectors are attracted to the hydrophobic carrier
particles. The collector-treated finely sized mineral
values attach themselves to the carrier parti~les which
carry them into the froth.
The carrier particles of this invention are
useful in beneficiating the finely sized mineral values
contained in finely sized ore pulps. Some finely sized
ore pulps are known in the art as slimes. ~he particle
size in slimes is different in different ores. From a
practical standpoint, a finely sized ore pulp is a
slime when the size of the ore particles interferes
with flotation. Examples of particle sizes in certain
slimes include phosphate ores with an average particle
size of about 150 microns, copper sulfide ores with an
average particle size of about 90 microns, cassiterite
ores with an average particle size of less than 6
microns and taconite ores with an average particle size
30,277-F -15-
~.288178
-16-
of about 10 microns. The term "finely sized" means
herein those particles of the size which create slimes
or which have an average particle size of less than 10
microns. "Finely sized ore particles" refers herein to
those ores being beneficiated which are finely sized.
"Finely sized ore pulps" refers herein to ore pulps
which contain a mixture of finely sized particles
. including the finely sized mineral values to be bene-
- ficiated.
The present invention, in its broadest aspect,
is not limited to the beneficiation of any species or
genus of finely sized ores since its benefits are
realized when employing a variety of ores in which the
slime is of natural or artificial origin. This process
may be applied with equally good results to feed in
which a valued component is concentrated in the froth
product or machine discharge product or in which both
froth and machine discharge products are valued materials.
Any fineIy sized ore may be beneficially
conditioned for froth flotation in accordance with the
present invention provided the components thereof,
which it is desired to separate, are liberated from
each other and one of said components must differ from
the other to the extent that it contains a substantial
amount of a component which is capable of being select-
ively treated with;a suitable collector compound; the
collector being held on the surface of the particles of
the component by chemical or physical forces or combina-
tions thereof.
30,277-F -16-
1288178
-17-
Examples of ores which may by beneficiated
using the carrier particles of this invention include,
cassiterite, phosphate, taconite, wolfamite, tantalite,
zircon, columbite, sheelite, magnesite, brurite, and
uranite ores, and ores containing copper minerals such
as chalcopyrite, chalcocite and cuprite.
.
The amount of carrier particles used can vary
- depending upon the particular ore which is beneficiated.
A suitable amount of carrier particles is that amount
which effectively enhances or improves the beneficiation
by flotation of finely sized ores wherein enhanced
means the total recovery is increased or the rate of
recovery is increased. A desirable range of concentra-
- tions of the carrier particles is from 0.5 to 20 percent
by weight of the feed charge. A preferred range of the
carrier particles is from 1 to 10 percent by weight of
the feed charge. The amount of carrier particles which
are necessary for this process is substantially less
than used in the prior art processes.
After the froth from the froth flotation pro-
cess has been removed from the flotation cell, the car-
rier particles can be separated from the finely sized
mineral values beneficiated by several well-known
methods. One method of separation is screening, where
the carrier particle size is significantly larger than
the size of the particles of the beneficiated ores.
Another method of separation is sedimentation. In one
embodiment, properly treated carrier particles float
only during turbulent conditions suitable for flotation,
so that when the froth product is dispersed in water in
the absence of such turbulent conditions, the carrier
particles settle and the beneficiated mineral values
30,277-F -17-
~-2~188178
would remain dispersed. Another separation method is to hydro-
cyclone the mixture of carrier particles and beneficiated mineral
values.
The froth flotation processes in which the carrier
particles of this invention are used, are those which are well-
known in the art. In most of these processes, the use of collec-
tors and frothing agents are required.
Numerous collectors are known in flotation practice or
have been proposed in the technical and patent literature. Generic
examples include xanthates, thiocarbamates, dithiophosphates, thio-
carbanilide, xanthogen formates, alkylamines, quaternary ammonium
compounds, sulfonates and the like. Any collector which is known
in the art as suitable for the beneficiation by flotation of a
particular ore can be used in this invention. Further blends of
known collectors can also be used in this invention.
Suitable frothers include collectors such as fatty acids,
soaps, and alkyl aryl sulfonates, but the best frothers are those
which have a minimum of collecting properties. They are polar-
nonpolar molecules of the type C5HllOH, amyl alcohol or CloH17OH,
the active constituent of the well-known frother pine oil. The
aliphatic alcohols used as frotherswhich preferably have chain
lengths of from 5 to 8 carbon atoms, provided there is sufficient
branching in the chain. Alcohols having from 10 to 12 carbon atoms
are also good frothers. Other examples include polyalkylene
glycOls, polyalkylene glycol ethers, polyoxyalkylene paraffins and
cresylic acids. Blends of frothers may also be used. All frothers
which are suitable for
~ 2~38~78
--19--
beneficiation of mineral ores by froth flotation can be
used in this invention.
The following examples are included for
illustration and do not limit the scope of the invention
or claims. Unless otherwise indicated, all parts and
percentages are by weight.
- In the following examples, the performance of
the frothing processes described is shown by giving the
rate constant of flotation and the amount of recovery
at infinite time. These numbers are calculated by
using the formula
1 -kt
- R = R~ [1- Kt ]
wherein: R is the amount of mineral value recovered at
time t; K is the rate constant for the rate of recovery,
and R~ is the calculated amount of the mineral value
which would be recovered at infinite time. The amount
recovered at various times is determined experimentally
and the series of values are substituted into the
aquation to obtain the R~ and K. The above formula is
explained in Klimpel et al., "The Engineering Characterization
of Flotation Reagent Behavior in Sulfide Ore Flotation",
XIV International Mineral Processing Congress, Toronto,
Canada, October ~7-23, 1982.
Example 1 - Comparative Experiment
Previously sized copper sulfide ore (1000 g)
(finer than 10 mesh) from the Cyprus Pima mine in the
30,277-F -19-
~Z88178
-20-
USA is placed in a rod mill with 600 g of deionized
water, 1.3 g of CaO to control pH in the range of
10.5+0.5, and Z~-200 (trademark of The Dow ~hemical
Company, (isopropyl ethylthionocarbamate) as collector
(0.045 kg/metric ton). The mixture is tumbled for 75
minutes until 98.9 percent of the solids pass through a
74 micrometer sieve. The slurry is introduced into a
. flotation machine ~specifically, a Galigher Agi~air
Flotation Machine) having a 3-liter capacity. The cell
agitator is run at 900 rpm. DOWFROTH~ 1012 (trademark
of The Dow Chemical Company), a polypropylene glycol
methyl ether having an average molecular weight of
about 400, is added to effect a loading of 0. 02 kg per
- metric ton of ore feed. Treated alumina trihydrate
particles (10 g, treated as described below) are also
introduced at this time and the slurry agitated for 2.0
minutes in a conditioning step, after which aeration of
the medium is initiated. The frothy concentrate is
collected in trays at time intervals of 0. 5, 1.0, 2.0,
3.0, 4.0 and 7.0 minutes using a motorized paddle to
remove the froth. The collected concentrate samples
are dried in an oven and weighed. Copper analysis of
each sample is accomplished by digesting the ore in
aqua regia using analytically weighed amounts that are
diluted to known volumes and recording the copper
concentration from an atomic plasma emission spectrometer.
In a similar manner anoth;er charge of copper
ore is ground and floated except no alumina trihydrate
particles are used. In like manner a third charge of
copper ore is ground and floated except no alumina tri-
hydrate particles are used and the frother concentration
of DOWFROTH~ 1012 is increased to 0.08 kg per metri-c
ton.
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~Z88178
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SB-31C series alumina trihydrate (Solem
Industries) of 90 micron median particle diameter were
surface treated in the following manner. A 1:2 molar
ratio of diethanolamine and dibasic fatty acid (sold
under the tradename Empol 101 ~Dimer Acid by Emery
Industries) i5 slurried as 0.1 percent by weight in
deionized water. Sufficient alumina trihydrate is
added such that the diethanolamine-dibasic acid weight
constitutes 0.1 percent of the alumina trihydrate
weight. After stirring for 15 minutes, the slurry is
rested for 5 minutes and the supernatant liquid decanted
from the sediment. The solids of the sediment are
dried in an oven and then heated above 140C to initiate
the condensation reaction between diethanolamine and
the carboxylate functionality of Empol 1010 on the
surface of alumina trihydrate. A heating time interval
of greater than 2 hours is sufficient. The solids are
cooled and broken apart using standard methods, such as
with roll mills and the like. Table I tabulates the
ultimate recovery, rate constant and grade of concentrate
recovery in these comparison examples.
TABLE I
Concentrate
Fro~her Concentration R K Grade
25- 0.02 kg/t with one per-
` cent treated alumina tri- 0.84 8.2 5.7% Cu
hydrate based on feed
0.02 kg/t with no
treated alumina 0.83 6.76.3% Cu
30 trihydrate*
0.08 kg/t with no
treated alumina 0.89 7.33.5% Cu
trihydrate*
*Not an embodiment of this invention.
30,277-F -21-
~ ~de inark
~2~8178
-22-
The data in Table I demonstrate the diffi-
culty of increasing the rate of flotation by increasing
the amount of frothing agent without carrying substantial
amounts of gangue material into the çoncentrate. Use
of the carrier flotation material increased the rate of
flotation without substantial loss of grade.
Exam~le 2
The surface treated alumina trihydrate as
prepared in Example 1 is introduced into deionized
water as a 50 percent slurry and boiled for 2 hours.
After allowing the solids to settle, the supernatant
liquid is decanted and the particles dried in an oven
and broken apart using a roll mill. The material is
self-floated to test if the surface treatment remains
intact from the water boil test. Over 90 percent of the
solid is recovered using the float cell and 0.10 kg
DOWFROT~ 1012 per metric ton of feed to produce a froth-
ing medium. The concentrate is dried and used for copper
ore flotation in the manner of Example 1. The results
are tabulated in Table II.
TABLE II
Concentrate
Example R K Grade
0.02 kg/t DOWFROT~ `
1012 with 1 percent 0.86 11.3 5.8% Cu
refloated alumina
trihydrate (treated)
The data in Table II demonstrates that the
surface treatment in Example I is not destroyed by boil-
ing in water and that the carrier particles can be reusedwith no additional treatment.
30, 277-F -22-
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ExamPle 3
In the manner described in Example 1, iron
powder of size passing a 149 micrometer sieve is slurried
in a water dispersion of a diethanolamine condensate
with tall oil fatty acid, a 1:2 molar ratio, prepared
by standard methods known to those in the art. The
t:'~ ~ monobasic acid is sold under the tradename of Emtall
729~ Emery Industries). A 0.05 percent by weight
- treatment of iron powder by this dispersion is effected.
Flotation of copper ore in the manner of Example 1 is
conducted. The results are given in Table III.
TABLE III
Concentrate .
Flotation Condition R K Grade
15 0.02 kg/t DOWFROTH~
1012 with 1 percent
treated iron powder 0.81 10.9 7.1% Cu
based on ore feed
.
The data in Table III show that a metal such
as iron can function as carrier flotation material when
treated in the manner taught herein.
Example 4
This example illustrates the efficacy of car-
rier flotation particles in the beneficiation of cassiter-
ite ore fines. A cassiterite ore from Keystone, SouthDakota of about 0.6 percent SnO2 is ground and fractionated
into two size fractions: material passing 63 micro-
meter and retained on a 44.5 microns and slime cassiterite
passing 44.5 microns. A microflotation cell of 315 ml
~ ~ ~qrk
30,277-F -23-
~288178
-24-
capacity (7 cm diameter and 11 cm depth in cylindrical
form) with an impeller of design equivalent to that of
the Agitair Flotation Machine but appropriately scaled
is used. Ore (50 g) is conditioned with Aeropromotor
845 from American Cyanamid Company (N-(1,2)-dicarboxyethyl-N-
-octadecyl sulphosuccinamate), a common collector for
cassiterite flotation. The conditioning time is 5
; minutes at 2000 rpm agitation. The pH is adjusted to
4.9 using hydrochlQric acid before conditioning.
I0 DOWFROTH~ 250 (0.06 kg per metric ton feed), a poly-
propylene glycol methyl ether of about 250 molecular
weight, is then added and the slurry conditioned one
additional minute. The impeller speed is reduced to
1750 rpm and aeration begun. Frothy concentrate is
collected for 5 minutes with a spatula. Air enters the
cell via a glass fritted plate at the bottom of the
microflotation cell. The concentrate is filtered,
dried in an oven, weighed and analyzed for tin content.
At a loading of 0.125 kg per metric ton of feed of
Aeropromotor 845 results in a recovery of 89 percent
SnO2 with a grade of 6.3 percent SnO2 for the coarser
fraction of ore (63 x 44 microns). On the other hand,
the slime cassiterite fraction (-44 microns) recovery
is only about 72 percent even with Aeropromotor at a
loading of 1 kg per metric ton of feed. The grade is
lowered to 3.1 percent. Reducing the level of Aeropro-
motor 845 to 0.50 kg per metric ton of feed reduces
recovery to 49.6 percent and gives a slight improvement
in grade (4.2 percent). In a manner similar to-this
last example, introduction of 10 percent carrier alumina
trihydrate particles, prepared in the manner of Example 1,
increases cassiterlte recovery to 94 percent with a
30,277-F -24-
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-25-
concentrate grade of 3.2 percent. The results are
compiled in Table IV.
TABLE IV
Ore
Collector Particle Carrier %
Run Amount size (~) Particle Recovery Grade
1* 1.0 kg/ton <i4 ~ no 72.0 3.1
2* 0.5 kg/ton <44 no 49.6 4.2
3 0.5 kg/ton <44 yes 10%** 94.0 3.2
*Not an embodiment of this invention.
**10 Percent by weight of the feed.
Runs 1 and 2 demonstrate the beneficiation of
the same ore pulp in which finely sized particles are
present. This data shows that the recovery of the
mineral values beneficiated and grade of the mineral
values recovered are significantly affected by the size
of the particles. Runs 1 and 2 also show that the use
of much larger amounts of collector wili not remedy the
low recovery or grade when finely sized particles are
present in the ore pulp. Run 3 demonstrates that the
use of the carrier particles of this invention increases
the recovery of the finely sized mineral values contained
in the finely sized ore pulp.
30,277-F -25-
