Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to a method for decreasing
metal losses in nonferrous smelting operations.
This application is a divisional application of copending
application ~o. 38~009 filed October 15, 1981.
A number of new processes for smelting copper and nickel
sulfide concentrates have been adopted on a commercia] scale
during the past thir-ty years. Well-known examples o~ such are the
Inco, Mitsubishi, Noranda and Outokumpu processes. Detailed
descriptions of these innovations are provided in the patent
and technical literature, e.g. Extractive Metallurgy of Copper,
Metallurgical Society A.I.M.E., 1976, Vol. 1. Desplte the
variety of their advantages they all suffer from the important
value element content of their furnace slage and the high content
of troublesome ultrafine concentrate particulate matter mechani-
cally extrained in their furnace exhaust gases. Furthermore, in
addition to copper, nickel, cobalt and the toxic, ubiquitous ele-
ment, arsenic, valuable, volatile metal and metalloid minor ele-
ments are often exhausted in said gases, e.g., antimony, bismuth,
cadmium, germanium, indium, lead, mercury, molybdenum, osmium,
rhenium, selenium, tellurium, tin and zinc. The furnace matte
also contains these impurity elements but a large fraction there-
of is conventionally returned to the furnace in converter slag
or in converter electrostatic precipitator dust. These
~\
,~
-- 1 --
..,.1~
elements are present in the furnace slag either in solution as
a homogenous mixture or as a heterogenous mixture of disseminated
matte entities suspended in the slag matrix. An external slag
scaven~ing procedure, e.g., slag flotation or electric furnace
treatment, is frequently employed to decrease loss of values in
the furnace slag; and an external dust recovery system, e.g~,
electrostatic precipitator, bag house, or wet scrubber, is con-
ventionally employed to decrease loss of values in the furnace
exhaust gas. Such installations are, furthermore, necessary to
prevent escape of toxic elements, e.g., arsenic, cadmium, lead,
and mercury, to the environment. It should also be noted that
the exhaust gas dust content can be troublesome in the steam
boilers usually employed to recover heat from said gas.
It is well known5 of course, that conventional copper
and nickel reverberatory furnaces suffer seriously from the
extravagant cost of their fossil fuel requirements, the un-
desirably low sulfur dioxide content of the voluminous and dustv
furnace gas~ the undesirably low value meta] concentration of
the furnace matte~ and the extravagant value metal content of
the furnace slag.
The prior art discloses internal furnace slag scaveng-
ing procedures for decreasing copper, nickel and cobalt losses
in sla~ by subjecting it to reducing reactions so as to decrease
its oxygen potential. Reference is made to the use of iron
sulfide, carbon and iron reductants as described by H. H. Stout
in U. S. Patent 1,544,048 and by Anton Gronningsaeter in U. S.
Patent 2,438,911. However, past attempts to apply concepts of
his nature on ~ commercial scale in the primary turnace have
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s~
not proven sufficiently rewarding, e.g., the procedure described
by one of the present applicants in U.S. Patent 2,668,107.
~ he present invention improves smelting practice by sub-
stantially decreasing the amount of value elements transported
out of the furnace by the slag. The present invention further
improves smelting practice by substantially decreasing the amount
of troublesome ultrafine concen-trate particulate matter transpor-
ted out of the furnace by the exhaust gas. The invention also
improves smelting practice by decreasing the net cost of effective
emission control of particulates, vapors, and sulfur oxides in
said gas through maximizing extraction, by vaporization from the
concentrate of volatile impurities, thus increasing the concentra-
tion of said impurities in the particulates collected and by in-
creasing the concentration of sulfur dioxide in said gas.
In copending application No. 388009 there is disclosed
a method for producing a metal matte from a nonferrous metal-
containing sulfide mineral concentrate, of a particle size of less
than about 65 mesh and containing particles of a size less than
about 5 microns, in a horizontally disposed furnace wherein a
molten charge of metal matte and a slag are present, beneath an
enclosed hot atmosphere, and exhaust gases, metal matte and slag
are separately discharged therefrom, the improvement where loss
of nonferrous metals is averted, comprising: (a) separating said
nonferrous metal-containing sulfide mineral concentrate particles
thereof having a siæe less than about 5 microns from the remainder
of said sulfide concentrate; (b) compacting said separated con-
centrate particles to form compacted concentrate for in-troduction
into said furnace and onto said slag; and (c) introducing the re-
mainder of said sulfide concentrate, flux and oxygen-rich gas
into an enclosed hot sulfur dioxide-rich atmosphere so as to effect
Elash oxidation of the sulfide concentrates therein prior to con-
tact of said concentrates with the molten slag, while injecting
~ 3
said compacted concentrate into the horizontal furnace and onto
said slay at a location spaced from the slag discharge of the
furnace.
~ ccording to the present invention there is provided a
method for producing a metal matte from a nonferrous metal-con-
taining sulfide mineral concentrate in a horizontally disposed
furnace wherein a molten charge of metal matte and slag are pre-
sent, beneath an enclosed hot atmosphere, an exhaust gases, metal
mette and slag are separately discharged therefrom, the improve-
ment wherein loss of nonferrous metals is averted comprising:(a) introducing said sulfide concentrate, flux and an oxygen-
rich gas into an enclosed hot sulfur dioxide-rich atmosphere so
as to effect flash oxidation of the sulfide concentrate therein
prior to contact of said concentrate with the molten slag; and
(b) sprinkling melted iron sulfide-rich sulfide concen-trate into
the furnace by means of a burner, using fossil fuel and oxygen-
rich gas as the main heat source therefor, to spread the same
onto the sl.ag, at a location adjacent and downstream from the
introduction of said sulfide mineral concentrate, flux and
oxygen-rich gas and spaced from the discharge for said slagO
The present invention also provides a method for produc-
ing a metal matte from a nonferrous metal-containing sulfide
mineral concentrate in a hori~ontally disposed furnace wherein
a molten charge of metal matte and a slag are present, beneath
an enclosed hot atmosphexe, and exhaust gases, metal matte and
slag are separately discharged therefrom, the improvement where-
in loss of nonferrous metals is averted comprising: (a) introduc-
ing said sulfide concentrate, flux and an oxygen-rich gas into
an enclosed hot su:lfur dioxide-rich atmosphere so as to effect
flash oxidation of the sulfide concentrate therein prior to
contact of said concentrate with the molten slag; (b~ sprinkling
a melted iron sulf:ide-rich sulfide concentrate into the furnace
- 3a
by means of a burner, using fossil fuel and oxygen-rich gas as
the main heat source therefor, to spread the same onto the slag,
at a location adjacent and downstream from the introduction of
said sulfide mineral concentrate, flux and oxygen-rich gas and
spaced from ~he discharge for said slag; and (c) injecting a
reductant material into the furnace, for spreading over the slag
at a location adjacent the sprinkling of said melted iron sulfide-
rich sulfide concentrate, and spaced from the discharge of said
slag, said reductant material being a metallic iron-rich material
containing at least one of the elements selected from carbon and
silicon.
The need for external slag scavenging procedures to
decrease value losses is averted by use of an oxygen sprinkle
smelting furnace in which the oxygen potential of the slag pro-
duced by several main feed concentrate burners is decreased by
its series treatment with increasingly strong reductants. These
burners operate at elevated temperature and produce matte of
high oxygen potential. Many of the elements listed above are
volatilized, leave the furnace as vapor or fume in the exhaust
gas, and therefore a major portion thereof is not trapped in either
furnace slag or matte.
Said increasingly strong reductants can be melted main
feed concentrate ultrafines followed by melted iron sulfide-rich
concentrates followed finally by a metallic iron-rich material.
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- 3b -
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~ 5
Said ul~rafines are preferably less than about 5
microns in diameter; they consist of the finest fraction of the
main feed concentrate and can be segre~ated readily in the course
of drying it. This material can be distributed over the slag in
S the form of briquettes or indurated pellets, or in liquid form
after melting it in any sùitable burner using fossil fuel and
oxygen-rich gas. The slag is then sprinkled with iron-rich
sulfide concentrate which has been melted by an oxygen sprinkler
burner using coal. The final reducing operation~ e.g., for major
increase in cobalt recovery, can be effected by spraying metallic
iron-rich particulate matter on the said slag, normally contain-
ing at least one of the e~ements of the group comprising carbon
and silicon.
The main feed burners are operated at elevated flam
temperatures, under conditions of superior interface contact and
mixing, and produce finely divided matte of high surface area
and of high oxygen potential. The sulfides of many of the ele-
ments listed above are readily volatilized as sulfides, metal,
or oxide vapors or fumes, and consequently report as such in the
gas exhaustecl from the urnaee and, therefore, do not get trapped
in furnace slag or matte.
Exhaust gas particulates, e.g. containing copper,
nickel or cobalt, and fumes or condensed vapors, e.~. containing
arsenie, bismuth~ eadmium, lead, molybdenum9 or zinc, are
eollected and extracted hydrometallurgically; and their copper,
nickel, and cobalt content can be returned to the smelting furnace,
if desired.
The accompanying drawing is a schematic illustration of
a cross-section of a horizontal furnace useful in the present pro-
cess showing the preferred locations for injecting the several
solid and gaseous feeds and for discharging the several products,
the slag and matte being in countercurrent flow and the slag and
gas in concurrent flow.
The present process is an improved me-thod for flash
smelting of nonferrous metal-containing mineral sulfides in a
horizontal furnace which substantially decreases loss of value
elements in furnace products. A particular flash smelting method
to which the present improved process may be applied is the
method described in our ~.S. Patent No. 4,236,915, entitled
"Process for Oxygen Sprinkle Smelting of Sulfide Concentrates".
The present process is particularly useful in the conver-
sion of copper, nickel and cobaltiferous sulfide concentrates, e.g.,
concentrates rich in minerals such as bornite, chalcocite,
chalcopyrite, carrollite, pentlandite, linnaeite, pyrite or
pyrrhotite, to high grade matte, clean slag and clean waste gas.
Concentrates containing minerals in this group are intro-
duced, along with flux material and oxygen-rich gas, into a hot
enclosed sulfur dioxide-rich atmosphere in a horizontal
5 5
¦furnace containing a molten matte layer on which floats a slag
layer, said layers being discharged at opposite ends of said
furnace. These sulfide concentrates are introduced into the
l enclosed hot sulfur dioxide-rich atmosphere by means of oxy~en
i ¦ sprinkler burners and mix and react effectively with the oxygen-
¦rich gas due to its large interface area at high temperatures¦ with the sulfide concentrates prior to contact of said concen-
¦ trates with the molten sla~ contained in the horizontal furnace.
¦ The term "oxygen-rich gas" is used herein to define gases which
¦contain 33% or more oxygen, up to and, includin~ tonnage oxygen
¦ which contains about 80-99.5% oxygen content.
¦ Very fast temperature rise within its paraboloid is
¦ achieved by the sprinkler burner because of its especially fine
¦ dispersion of feed metal sulfide particulates in the carrier
¦ oxy~en-rich gas. The resulting extremely large reactant interface
¦ area takes maximum advantage of the high rate of the exothermic
¦ chemical reaction between ferrous sulfide and oxygen for the for-
¦ mation of ferrous oxide and sulfur dioxide. Furthermore, any
¦ boundary layer resistance to mass transfer in this reaction i's
¦ minimized by the m;xing and scrubbing actlon imparted to the
¦ system at exit from the sprinkler burner. Thus, flame temperature
¦ in the upper portion o the paraboloid exceeds 1450C. As a con-
, ¦ sequence, the feed sulfide mineral particles are almost instan-
¦ taneously converted to discrete liquid droplets at temperatures
¦ so elevated as to vaporize the major portion of contained
elements having unusually high vapor pressures in their elemen-
tal, sulfide, or oxide states.
j ~ 11955
¦ These elements include, specifically, arsenic, bismuth,
¦cadmium, lead, molybdenum, and zinc, or their compounds. When
¦present in the sulfide concentrate in minor but important quanti-
¦ties, over 75% of these volatiles will report as vapors or fumes
S ¦in furnace exhaust gas, whence they can be recovered by conven-
tional means, e.g. collected by electrostatic precipitators and
wet scrubbers, and isolated by hydrometallurgical extraction^
In this manner, their dissolution in, or reaction with the fer-
rous silicate or metal sulfide phases of the furnace bath is min-
imized, which may be most advantageous due to the difficulty orcost of their subsequent removal and isolation, e.g. from a sub-
sequent metallic phase.
In the lower portion of the paraboloid the system has
lost most of its radial velocity so that the well mixed par-
ticulate mat~er descends relatively slowly to the slag surface.Elapsed time in this portion is about an order of magnitude
greater than in the upper portian, sufficient so that excel~
lent heat transfer between the gas-liquid-solid phases of
the dispersoid is efected. In addition to providing further
time for impurity ~olatilization, the ferrous oxide-rich
and silica--rich particles rain gently down on the slag sur-
face at temperatures exceeding 1300 C., collide intimately
thereon~ amd reaet efficiently in the bath for desired rapid
production of errous silicate. Ferric oxide-rich and ferrous
sulflde-rich particulates react likewise for desired effi-
cient reduction of magnetite to ferrous oxide, with concomi-
tant oxldation of ferrous sulide to ferrous oxide and sulfur
. , .
.
Il _7_
8~55
¦dioxide. The overall effect of this process is to ensure that
¦furnace slag approaches equilibrium with the matte draining there-
¦through and has high fluidity for superior slag-matte separation.
¦It should be noted that succeeding paraboloids in the furnace
¦gas stream act as spray scrubbers for previously gas-borne fine
¦particulates moving downstream.
The nonferrous metal-containing concentrates are intro-
duced in a dry, finely divided state, preferably uniformly mixed
with Elux, and are preferably of a particle size less than about
65 mesh to provide for rapid reaction of the sulfide particles
with oxygen in the gaseous phase above the molten sla~ within
the furnace prior to contact of the particles with said molten
slag, and thereafter from rapid reaction of the metal oxides
so produced with ferrous sulfide and flux.
A typical such nonferrous metal-containing concentrate
may csntain about 10 percent by weight of particles of a size
less than about 5 microns, the value metal analysis of which may
be of the same general order as that of the total concentrate.
Thi~ semi-colloidal dust is readily transported out o the fur-
nace in the exhaust gas before it-~can settle OlltO the molten
bath. Some of it accumulates in the flues or builds accretions
in waste heat bollers, while the remainder burdens the dust
recovery units an~d dilutes the concentration of impurity elements
in the recovered dust.
According to the present process, the nonEerrous metal-
containing sulfide concentrates, of a particle size less than
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, 11 .
~ ~8:1L95
I
I .''
¦about S microns, may be separated from the remainder of the con-
¦centrates incidental to water removal, e.g. by fluid bed drying,
and this fine particle size material is treated to compact the
¦same. The ultrafine material, of -S micron size, can be compacted
¦bY liqueaction and can be injected into the furnace in the
¦molten state by melting it in any suitable burner using fossil
¦fuel and oxygen-rich gas as the main heat source. An example of
la suitable burner in the furnace sidewall is of the cyclone type
¦with its long axis inclined downward at a substantial angle from
¦the horizontal, e.g. 30. Alternatively, the particles may be
¦compacted by agglomeration, preferably by forming indurated
¦pellets of a size in the range of about 1 mm to 10 mm in diameter.
¦In the making of these agglomerates, there may also be in-
¦corporated other materials such as residues or other products
from the hydrometallurgical treatment noted above.
These compacts, elther molten material or agglomerates~
are injected into the horizontal furnace through the roof or
sidewalls and onto the slag at a location preferably just down-
stream from the last main concentrate sprinkler burner paraboloid
suspension.
In the present invention9 the slag formed during flash
smelting Qf nonferrous metal-containing sulfide concentrates is
cleaned by decreasing the oxygen potential o the slag through
the series addition thereto of increasingly strong reductant
material, i.e., its magnetite content is progressively ~educed
. .."
_9_
..
to a satisfactorily low level such as about 5%, by weight, or less.
For this purpose~ it is highly advantageous to have the matt e and
slag in countercurrent flow and the slag and gas in concurrent floh
An important feature of -the present invention is the a~ ty
to maintain high slag tem ~rature with resulting low slag viscosity
The first of the series of reductants added is the moderate
grade matte resulting from the melting of the compacted ultrafine
concentrate particles~ the compacted particles being introduced
into the furnace and onto the slag at a position adjacent the last
paraboloidal suspension and spaced from the slag discharge end of
the furnace. ,~
The second of -the series of reductants added is a low grade
concentrate, low in nonferrous metal content and rich in iron sul-
fide content, which effects slag cleaning by the combined chemical,
lS dilution and coalescing washing effects resulting from sprinkling a
liquid matte rich in iron sulfide and poor in nonferrous metal con-
tent over the slag, drenching it therewi-th. An example of such
naterial is a chalcopyrite-pyrite middling concentra-te which may
contain 4$ copper, by wei~ht, or a pyrite concentrate which may
contain 0.5% copper, by weight. Another example is a pentlandi-te-
pyrrhotite middling concentrate which may contain 2% nickel by
weight or a pyrrhotite concentrate which may contain 0.6% nickel,
by weight. An important chemical effect of the iron sulfide is re-
duction of the magnetite and ferric iron content of the slag to
ferrous oxide, concomitantly transforming dissolved nonferrous
metal oxides to sulfides for their entry into the matte. The re-
duction of the magnetite is accompanied
11~Y3L9~5
b an impor-tant decreaee in slag viscosity and ~herefore more
rapid and c:omp]ete se~tling of suspended mat~e. There is an
additional beneficial mixlng action caused by S02 ebullition
resulting from the chemical reaction. The present embodiment
¦ of the invention then further increases the f~rnace value metal
recovery by decreasing the oxygen potential of the slag beyond
¦ that obtainable by use of iron sulfide addition alone. This
¦ is achieved in the last of the series reductant additions.
¦ Such practice can triple the cobalt recovery obtained in nickel
L0 ¦ reverberatory furnace operation. Thè relatively small amount
of reductant spread over the slag in the last case, e.g. 2 per-
cent, by weight, of the slag, is rich in metallic iron, and
normally contains at least one element selected from the group
comprising carbon and silicon, e.g., pig iron, silvery pig iron,
ferrosilicon~ sponge iron or scrap iron, such as gray iron boring
chips. ~ow grade, high carbon, high sulfur sponge iron is a
satisfactory reductant which can be reaclily and economically
prodùced from pyrrhotite concentrate or middling, now stockpiled
by the nickel industry. Carbon alone, as is known, can be used
as a reductant, but its efficiency is usually poor due to its
low specific gravity, which causes it to float on the slag,
and its top injection into the slag, e.g., by roof lances, can
cause operating difficulties. This last of the series of re-
ductant additions is effected by spreading the same over the
~5 slag at a position spaced from the slag discharge end of the
horizontal Eurnace sufficiently remote from the tap holes to
pro ide adequate cettling time Eor the new matte formed.
1l1
~.
~ 5
As an example of the maJOr benefits conferred by the
present invention over prior nonferrous smelting furnace prac-
tice, a chalcopyrite concentrate analyzing 25% Cu~ 28~/o Fe~
31% S, and 8% SiO2,and a minor but important amount of arsenic,
bismuth, cadmium, lead, molybdenum, and ~inc, totaling less than
2 % by weight of the concentrate, is separated into approximately
plus and minus 5 micron fractions by air elutriation in the
course of fluid bed drying. The thus segregated ultrafines,
having a weight of 7% of the total concentrate and a chemical
analysis similar thereto are compacted by meltin~ using a furnace
burner employing oxygen and fossil Euel~ and the resulting matte
is spread over the slag at a location adjacent the last parabo-
loidal suspension of a system of three such paraboloidal suspen-
sions. The balance of the concentrate is oxy~en sprinkle smelted
to a high grade matte em~loying commercial oxygen and three
sprinkler burners. A major portion of the minor element impuri-
ties, e.g., arsenic, bismuth, cadmium, lead, molybdenum, and
zinc, is vaporized because of the paraboloid flame conditions
of excellent interface contact and mixing at high temperatures,
exceeding 1450C, and high oxygen potential, corresponding to a
matte grade exceeding 65% copper, in the paraboloids. The
furnace gas, analyzing over 20% SO2 by volume, is exhausted from
the furnace continuously, and contains over 75% of the arsenic,
bismuth, cadmium, lead, molybdenum, zinc and sulfur content,
2S respectlvely, in the overall sulfide feed. A slag cleaning reduc-
tant, introduced adjacent the means for introduction of the
~ , .
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11819S5
liquefied ult-afine material, remote from the slag discharge
for adeguate matte settling purposes, comprises a chalcopyrite-
pyrite middling analyzing 4% Cu, 40% Fe and 45% S is melted
and sprinkled over the slag. The high grade matte produced
analyzes 65% Cu, 10% ~e and 22% S, while the fina'l slag analyzes
0.4% Cu~ for a recovery of over 98% of the copper.
As a further example of the present method, a pentlan-
dite concentrate analyzing 12% Ni, 0.4% Go, 38% Fe, 31% S and
8% Si~ and a minor but important amount of cadmium, lead, and
zlnc, totaling less than 1%, by weight, of the concentrate,
is separated into approximately plus and minus 5 micron fractions
by air elutria~ion in the course of fluid bed drying. The sepa-
rated -5 micron particulate material, having a weight of 7%
of the total concentrate and a chemical analysis similar thereto,
is compacted as 1-10 mm indurated pellets which are injected
into the furnace and spread over the slag at a location adjacent
the last paraboloidal suspension of concentrates. The remainder
of the concentrate is oxygen sprinkle smelted to a high grade
matte employing commerc~al oxygen and a plurality of oxygen
sprinkle burners. Under the resulting ~onditions of high tempera-
tures, exceeding 1450 C, and high oxygen potential in the
paraboloids corresponding to a matte grade exceeding 55% Ni,
the major portion of the minor element impurities, cadmi~mg
lead and zinc present in the concentrate leave the furnace in
2S ' the exhaust gas as vapor or fumes. This gas, analyzing over
20% S02 by volume, is exhausted from the' furnace continuously,
with over 7S% of the cadmium, lead sulfur and zinc content
.`
:. . ' , .
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, c
1, .
l . , 1
of the overall su]fide feed. An iron sulfide-rich slag cleaning
i reductant, comprising pentlandite-pyrrhotite middling analyzing
2% Ni, 56% Fe and 34~/O S, i.5 melted and sprinkled over the slag
by means of an oxygen sprinkler burner employing fossil fuel
¦ as a heat source, adjacent the introduction means for the com-
pacted ultrafines and remote from the slag discharge for adequate
matte settling purposes. The flnal reductant of the series
of reductant additions, comprising granulated pig iron containing
¦4.5% C and 1.5% Si, is introduced sequentially into the furnace
¦adjacent the last named molten addition and adequately spaced
¦from the slag discharge of the furnace. The high-grade matte
produced analyzes 55% Ni, 1.55% ~Co, 10% Fe and 26% S, while
the final slag analyzes 0.15% Ni and 0.07% Co, for a recovery
o about 99~/O and 83~/o of the nickel~and cobalt, respectively.
The figure schematically illustrates locations of
the injection ports for injection of the ultrafine concentrate,
in agglomerated or liquid form, of the iron sulfide-rich concen-
trate in liquid form and of the iron-rich reductant material
accordiAng to the present process where oxygen sprinkle smelting
of concentrates is effected. The ho~izontal furnace l, has a
slag outlet 3, a matte outlet 5, and an exhaust gas outlet 7.
A charging rneans 9 is present for return of converter slag. A
molten matte 11 is present in the lower portion of the furnace
with a layer of molten slag 13 thereover. A heated sulfur dioxide-
rich atmosphere is enclosed in area 15 between the slag layer
13 and the roo of t:he furnace. Three oxygen sprinkler burners 19
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Il ' ' - 1
~L18~9S5
are provlded' to generate suspensions of sulfide concentra~e S
and oxygen-rich gas, and preferably flux F, in the heated atmos-
phere of the furnace. Mixtures of su'lfide concentrate and flux
are charged through lines 21 to burners 19. Oxygen-rich g~s is
fed through lines 23 to form parabo,Loida'l suspensions 25 within
the hot atmosphere in the area 15 of the furnace. There is pro-
vided an injection means 27 adjacent the final paraboloid 25 and
spaced from the slag discharge 3 for injection of the compacted
ultrafine particulate nonferrous metal mineral concentrates 29,
in agglomerated or molten form, into the furnace and onto the
slag layer 13. Also provided is an injection means 31, adjacent
means 27 and spaced from slag discharge 3, for sprinkling of a
low ~rade concentrate 33 high in iron sulfide content and low
in nonferrous metal conten~, into the furnace and onto the slag
layer 13. There is also provided an injection means 35, spaced
from the slag discharge end 3 of the furnace and sufficiently
remote from the tap hole 5, for injection of the metallic iron-
rich material 37 into the furnace and onto the slag layer 13.
As will be understood by those skilled in the art, some
embodiments of this invention can be employed to improve other
1ash smelting or continuous processes, however, its application
to the oxygen sprinkle smelting process and apparatus is particu-
larly advanta~eous because its heat and mass transfer and distri
bution are favorable, and because -the required reverberatory fur-
nace modifications are relatively simple and inexpensive.
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