CA1181955A - Method for decreasing metal losses in nonferrous smelting operations - Google Patents
Method for decreasing metal losses in nonferrous smelting operationsInfo
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- CA1181955A CA1181955A CA000456419A CA456419A CA1181955A CA 1181955 A CA1181955 A CA 1181955A CA 000456419 A CA000456419 A CA 000456419A CA 456419 A CA456419 A CA 456419A CA 1181955 A CA1181955 A CA 1181955A
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Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a method for producing a metal matte from a non-ferrous metal-containing sulfide mineral concentrate in a horizontally disposed furnace wherein a molten charge of metal matte and slag are present, beneath an enclosed hot atmosphere, an exhaust gases, metal matte and slag are separa-tely discharged therefrom, the improvement wherein loss of non-ferrous metals is averted comprising: (a) introducing said sulfide concentrate, flux and an oxygen-rich gas into an enclosed hot sul-fur 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 concentrate 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 slag, at a location adjacent and downstream from the introduction of said sulfide mineral concentr-ate, flux and oxygen-rich gas and spaced from the discharge for said slag.
The present invention provides a method for producing a metal matte from a non-ferrous metal-containing sulfide mineral concentrate in a horizontally disposed furnace wherein a molten charge of metal matte and slag are present, beneath an enclosed hot atmosphere, an exhaust gases, metal matte and slag are separa-tely discharged therefrom, the improvement wherein loss of non-ferrous metals is averted comprising: (a) introducing said sulfide concentrate, flux and an oxygen-rich gas into an enclosed hot sul-fur 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 concentrate 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 slag, at a location adjacent and downstream from the introduction of said sulfide mineral concentr-ate, flux and oxygen-rich gas and spaced from the discharge for said slag.
Description
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 ~\
,~
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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
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~
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
-2-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.
-- 3b -` c-"l ~ 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 ¦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 , 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 ~ , .
. ', 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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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 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.
'-15- `
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.
-- 3b -` c-"l ~ 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 ¦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 , 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 ~ , .
. ', 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 .`
:. . ' , .
, 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 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.
'-15- `
Claims (14)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method for producing a metal matte from a non-ferrous metal-containing sulfide mineral concentrate in a horizon-tally disposed furnace wherein a molten charge of metal matte and slag are present, beneath an enclosed hot atmosphere, an ex-haust gases, metal matte and slag are separately discharged there-from, the improvement 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 there-in prior to contact of said concentrate with the molten slag; and (b) sprinkling melted iron sulfide-rich sulfide concentrate 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 slag, 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 slag.
2. In a method for producing a metal matte as defined in claim 1, the improvement wherein the major said nonferrous metal is copper.
3. In a method for producing a metal matte as defined in claim 1, the improvement wherein the major said nonferrous metal is nickel.
4. In a method for producing a metal matte as defined in claim 1, the improvement wherein the major nonferrous metals are copper and cobalt.
5. In a method for producing a metal matte as defined in claim 1, the improvement wherein said metal matte and slag flow concurrently in said furnace.
6. In the method for producing a metal matte as defined in claim 1, the improvement wherein said sulfide concentrate and oxygen-rich gas is sprinkled into said enclosed hot sulfur dioxide-rich atmosphere, a major portion of said sulfide concentrate and oxygen-rich gas being injected as a mixture through a plurality of vertically disposed burners on said furnace into said enclosed sulfur dioxide-rich hot atmosphere as a plurality of paraboloidal suspensions, so as to effect substantially uniform heat and mass distribution over a major portion of said horizontal furnace.
7. In a method for producing a metal matte from a non-ferrous metal-containing sulfide mineral concentrate in a horizon-tally disposed furnace wherein a molten charge of metal matte and a slag are present, beneath an enclosed hot atmosphere, and exhaust gases, metal mette and slag are separately discharged therefrom, the improvement wherein loss of nonferrous metals is averted com-prising: (a) introducing said sulfide concentrate, flux and an oxygen-rich gas into an enclosed hot sulfur dioxide-rich atmos-phere 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 sulfide rich sulfide concentrate 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 slag, 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 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.
(b) sprinkling a melted iron sulfide rich sulfide concentrate 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 slag, 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 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.
8. In the method of producing a metal matte as defined in claim 7, the improvement wherein said nonferrous metal is selected from the group comprising copper, nickel, cobalt, or mixtures thereof.
9. In the method for producing a metal matte as defined in claims 7 or 8, the improvement wherein said sulfide concentrate and oxygen-rich gas is sprinkled into said enclosed hot sulfur dioxide-rich atmosphere, a major portion of said sulfide concentr-ate and oxygen-rich gas being injected as a mixture through a plurality of vertically disposed burners on said furnace into said enclosed sulfur dioxide-rich hot atmosphere as a plurality of para-boloidal suspensions, so as to effect substantially uniform heat and mass distribution over a major portion of said horizontal furnace.
10. In the method for producing a metal matte as defined in claim 7, the improvement wherein said metallic iron-rich material is selected from pig iron, silvery pig iron, ferro-silicon, sponge iron and scrap iron.
11. In the method for producing a metal matte as defined in claim 7, the improvement wherein said nonferrous metal-contain-ing sulfide mineral concentrate is a nickel and cobalt sulfide mineral concentrate rich in nickel, and wherein the metal matte produced contains more than 50% combined nickel and cobalt by weight, representing more than 98% of the nickel and more than 80% of the cobalt in the concentrate fed to the furnace, by weight, and the exhaust gas the furnace contains more than 20%
sulfur dioxide by volume, representing more than 75% of the sulfur in the combined sulfide concentrates fed to the furnace, by weight.
sulfur dioxide by volume, representing more than 75% of the sulfur in the combined sulfide concentrates fed to the furnace, by weight.
12. In the method for producing a metal matte as defined in claim 7, the improvement wherein said nonferrous metal-contain-ing sulfide mineral concentrate is a copper, cobalt, nickel sulfide mineral concentrate, rich in copper and cobalt, and wherein the metal matte produced contains more than 50% combined copper and cobalt by weight, representing more than 98% of the copper and more than 80% of the cobalt in the concentrate fed to the furnace, by weight, and the exhaust gas from the furnace contains more than 20% sulfur dioxide by volume representing more than 75% of the sulfur in the combined sulfide concentrates fed to the furnace, by weight.
13. In the method for producing a metal matte as defined in claim 7, the improvement wherein said nonferrous metal-contain-ing sulfide mineral concentrate is a copper sulfide mineral con-centrate containing minor but important quantities of arsenic, bismuth, cadmium lead, molybdenum, and zinc, and wherein the metal matte produced contains more than 50% copper by weight, representing more than 98% of the copper in the concentrate fed to the furnace, by weight, and the exhaust gas from the furnace contains more than 20% sulfur dioxide by volume and more than 75%
of said arsenic, bismuth, cadmium, lead, molybdenum, sulfur, and zinc in the combined sulfide concentrates fed to the furnace by weight.
of said arsenic, bismuth, cadmium, lead, molybdenum, sulfur, and zinc in the combined sulfide concentrates fed to the furnace by weight.
14. In the method for producing a metal matte as defined in claim 7, the improvement wherein said nonferrous metal-contain-ing sulfide concentrate contains at least one nonferrous metal selected from the group consisting of copper and nickel, and minor but important quantities of at least one of the minor elements selected from the group consisting of antimony, arsenic, bismuth, cadmium, germanium, indium, lead, mercury, molybdenum, osmium, rhenium, selenium, tellurium, tin, and zinc, and wherein the metal matte produced contains more than 50% by weight of said non-ferrous metal of the group above defined, representing more than 98% of said nonferrous metal in the concentrate fed to the furnace, by weight, and the exhaust gas from the furnace contains more than 20% sulfur dioxide by volume and a major portion of said at least one minor element, said sulfur dioxide in the exhaust gas representing a major portion of the sulfur, in the combined sulfide concentrates fed to the furnace by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000456419A CA1181955A (en) | 1980-10-16 | 1984-06-12 | Method for decreasing metal losses in nonferrous smelting operations |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US197,563 | 1980-10-16 | ||
| US06/197,563 US4337086A (en) | 1978-12-21 | 1980-10-16 | Method for decreasing metal losses in nonferrous smelting operations |
| CA000388009A CA1181954A (en) | 1980-10-16 | 1981-10-15 | Method for decreasing metal losses in nonferrous smelting operations |
| CA000456419A CA1181955A (en) | 1980-10-16 | 1984-06-12 | Method for decreasing metal losses in nonferrous smelting operations |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000388009A Division CA1181954A (en) | 1980-10-16 | 1981-10-15 | Method for decreasing metal losses in nonferrous smelting operations |
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| Publication Number | Publication Date |
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| CA1181955A true CA1181955A (en) | 1985-02-05 |
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| CA000456419A Expired CA1181955A (en) | 1980-10-16 | 1984-06-12 | Method for decreasing metal losses in nonferrous smelting operations |
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1984
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