US2668107A - Autogenous smelting of sulfides - Google Patents

Description

Feb. 2, 1954 J. R. GORDON I'AL AUTOGENOUS SMELTING 0F' SULFIDES Filed June 25. 1949 3 Sheets-Sheet l Jaffe-s Raya/Mfr Gama/v Feb 2, 1954 J. R. GORDQN mL 2,668,107

AUTOGENOUSSMELTING OF SULFIDES Ei'led June 25., 1949 -3 Sheets-Sheet 2 Feb 2 1954 J. R. GORDGN Erm.

AUTOGENOUS SMELTING OF- SULFIDES 3 Sheets-Sheet 3 Filed June 25, 1949 Patented Feb. 2, 1954 UNITED STATES PATENT OFFICE AUTOGENOUS SMELTING F SULFIDES Application June 25, 1949, Serial No. 101,336 y Claims priority, application Canada May 13, 1949 (Cl. 'J5-74) Claims.

The present invention relatesto the art of treating nickel and copper sulfide ores, and, more particularly, to the art of autogenously smelting finely divided sulde ores or concentrates containing iron, nickel and/or copper for the production of matte and slag.

A well-known procedure typical of conventional practice for the production of nickel-copper matte and blister copper from nickel-iron sulde and copper-iron sulfide bearing ores, such as those of the Sudbury district, involves a flotation concentration of the ore into one or more nickel-iron sulfide concentrates (mainly pentlandite and pyrrhotite) and a high-grade copperiron sulfide concentrate (mainly chalcopyrite). The nickel concentrate is roasted and the `resulting calcine is smelted in a reverberatory furnace to obtain reverberatory matte which is bessemerized tc produce a. substantially iron-free, nickel-rich matte also containing copper. -Silnilarly, the copper concentrate is smelted in a reverberatory furnace, separately from the calcined nickel concentrates, to obtain reverberatory matte which is then bessemerized to produce blister copper. Bessemerizing the reverberatory mattes produces nickel-rich and copper-rich slags which are treated for metal recovery by passing through the reverberatory furnaces.

Smelting by the foregoing and other conventional procedures has disadvantages in that costs of heating by carbonaceous fuel or electricity are high and in that diiculty may be encountered in securing discard slags as clean as desired. Various proposals have been made in the past for the suspension or flash smelting of sulilde ores and concentrates in order to decrease or eliminate the use of carbonaceous fuel or electric power. Thus H, H. Bridgeman in U. S. Patent No. 578,912 1897) proposed ilash smelting of pulverized sulfide ore and flux in a reverberatorytype furnace to produce matte and slag. Use of preheated air for flash smelting of suldes was recommended inthe Klepinger, Krejci and Kuzell U. S. Patent No. 1,164,653 (1915).

and P. B. Bryk, in British patent applicationy 23,546/48, claim use of air preheated by the fur- J. W. Ryselin I nace exit gases and use of a downwardly directed burner. H. Freeman in 1930 Adisclosed having flash melted Gepest sulfide otationmcentrate.

in his U. S. Patent No. 2,209,331 disclosed a process for the production of elemental sulfur by a reaction between sulfur dioxide and flash smelted sulfide particles suspended Within thev sulfur 'l dioxide and mentioned the :dash smelting of sulg des containing copper or nickel with flux and oxygen-rich gas to produce a molten bath. In

the Kaling and Brannstroin U'. S. Patent` No.

2,295,219, separate preparation of a molten iron Y sulfide product prior to its use in slag cleaning operations is disclosed. The Brannstrom andsundstrom swedish Patent No. 118,492 1947) disclosed the flash smelting of pyrite over slag wherein the free atom of sulfur in the pyrite (FeSz) is burned to assist in melting the re- A mainder of the pyrite and thus toform a spray of molten iron sulde for slag cleaning purposes.

However, some of the above processes have serious shortcomings and others are not applicable to pyrrhotitic nickel-containing ores.

We have discovered an improved process forthe production of matte rich in nickel and/or copper, directly from nickel and/or copper conl centrates, which involves a novel combination of operations and which produces concomitantly a' slag relatively 10W in nickel and/or copper.

It is an object of the present invention to pro'- vide an economical method for autogenously smelting sulde ores and concentrates containing iron and nickel and/or copper to prcduce'matte or metal and a slag relatively low in nickel and/or copper.

Another object is to provide a method of smelting sulfide ores and concentrates containingiron, nickel and/or copper by utilizing the material being treated as fuel to providethe necessary smelting temperatures toY obtain a matte containing nickel and/or copper and, concomitantly, a slag low. in nickel and/or copper and containing acentrate oventhe slag-whereby said.slagwistwasl-iedwith a shower# ofmolten-:iron-rich matteiA dropi lets.

The present invention vcontemplates as an addi-.Vv tional object providing a process for autogenously smelting both nickel and/or copper dsul'de concentrates and pyrrhotite concentrate to. produce high-grade matte and low-grade slag1 .and,..cone.-

comitantly, producing gas containinghighonevcentrations of sulfur dioxide.y

Other objects and advantages will become-.ap--- parent from the following descriptiontakenfinf conjunction with the drawings, in which:

Fig. 1 is a schematic diagrammi. aniembodiment of the present invention in which a nickel and/ or copper sulfide concentrate is-autogenously smelted to produce nickel and/or copper-rich matte and slag rich in nickel and/or copper and in which, alternatingly, Dyrrhotite concentrate 10W` Ain `nickell and/or-copper antogenously` smelted intliesame iurnacettogproducea' shower of"mclten low=grade-matte and' slag which' re moved-nickelland/o1" copperfrom^said-rich slag? Fig." Zdepicts`A a-1nodirication'A of thenovelproc-A essin -vvlfxicliA the--autogenous-- smelting -of both nickel-and/or coppery suldeconcentrate' and pyrrliotitelconcentrate can take placeA simulta neorusly`1 through burners 1 locatedatv different--4 positions-'inthe same furnace,- thenickel and/or copper-richematte -being tapped vfrom the -high grade endl@ of fsaid furnaceand the slag beingv` tapped-rom the-lowgrade orpyrrhotite end of the furnace, Wherebythe rich slag -is depleted of nickel f and/orl copper by the low-grade matte 'f shower-andiby countercurrent-flovveof` matte relative to slag;

Fig. 3 illustrates anethenmodication ofthe processL in-whielrthefurnace isprovided withv aL heartltpartitionon-barrier to separatethemolten loW-grade1-mattefrom the molten high-grade matte-'butwhich permits the slag-from thehigh` grade endf of# the furnaceto -flowover-anddnto tlieslow-grade end -o the furnaceior purposesofA nickelfaaid f o1=copper-recovery-from-'said slag and Figaltsl-lows `still another modification of" tl'iel presentlfinvention in which the preductionL ofV Y' incitanl low-'grade -matteby theeautogenouslsmelt ing cihmzrrhotite` concentrate andtheshoweringw of said lovv-gradematte-onto-` the moltcnslagy ricl-r` irrnickelland/or copper occurs in a'furnace separate fromfthe furnace in which high-grade matte andfrich slag are produced.

Thepresentainvention comprises `anovel Vcom-- binationarofioperations for` either. simultaneously; or cyclicallyautogenously smeltingstwo, sulde materialsfof' different compositions with uxnone sulderconcentrate being rich in. nickel and/.or copper Y and ther other. sulfide concentrateA being, lowiin nickel and/or copper. sulfide but rich in. pyrrhotite. The novel. process utilizes the exo-v therrnic reactions occurring between metalsul-A ildes and gases containing a sufficientlyhigh'concentration of free oxygen to autogenously smelt. saidlsuln'des andflux to produce matte and slag. or even metal and slag.

When thev present invention is ycarried into practice; it involves coordinatedV control over various-metallurgical andmechanical factorsgjirr-V cludingfcompositions, absolute andl relative particle sizes and moisture contents of the sulfide concentrates and flux, the free-oxygen contents of the burner gas and the ratios of free oxygen and siliceous flux to sulfide concentrates, furnace dimensions, and furnace temperatures. For in stance, great care must be taken to insure exact proportioning fandcmixinggofftheivarious components;v of' thezburner feedgincludinga the oxygen, and also the rate of injection thereof into the furnace. Proper furnace and burner construction.as described. hereinafter are important in obtaining optimum operation. The ratio of siliceoussiiuxv.tosulde concentrate is predetermined-bythedegreelof iron suliide oxidation desiredyaire", tlieaznount of iron oxide formed, and

tne-silicaainfthesulfidedlux mixtures must be inA-amountsuicientto form a suitable slag with tiieironoxidepro'duced.

In order to' initiate the exothermic reaction y betiveemtheiromsulde fraction of the concentrate and the free oxygen of the gas, the furnace into`which-the-mixture is injected must be preheatedvto over about 1500 F., and preferably over about 2000a F., by means of, for example, oil, coal or gas ring.

In tliatp'art'of *theprocess'involvingthe autogencussmeltingoff high-grade nickel 'and/or cop*- per-sul'd'e concentrate; it is desired that-sufiicieni'.'V of the ironsulfide fraction be' oxidizedttoform" ironA oxide and lgaSeOuSsulur dior'iide'toA produce` the desired grade of matte; due consideration being given to'maintenance offsuitable furnace temperature; While-at the same Atime-it is also desired -to/ have as little as possible ofthe nickel and/or.coppersuldefccncomitantly-oxidizedfintot the slag: However; separationofa majonportionof theiron; asan oxide in theslag;fromtl'ie` copper and/or'nickel matte -is not commercially feasible Without' unavoidable production of slag`- suiii-'ciently rich in nickel and/or copper tovvarhu rant recovery therefromof these valuableelements.- The present invention contemplates as an essential feature, in novel combination withthe `aforernentionedJautogenous smelting of nickel and/or copper-suliideconcentrate; the operationY of" slagfcleaning by autogenously"smelting pyrrhotitefconcentra-te to'produce a shower'of lowgrade-matter and slag-Which falls on the aforementioned rich1 slag:

In" order` toproduceY aI low-grade,y iron-richA matte1 suitable' for slage-cleaning purposes,` and a`v portion*k offthe -pyrrhotite concentrate `is oxidized; in the presence of iiux; they remaining` lporti-onv` being4 melted by combustion of i the portionl oxidizedif Tide-molten,L unoxidizedliron suld'efrac-- tion :oi the autogenously -smeltedX py-rrhotite con centrate xupon coming; into intimate contact: with'- the 1Yl'iigh-gradei` or: richr. slag obtained `fron-11 the nickel.- and/ or *copper* sulfide? smelting' operation recovers.- nickel; and/or copper; values: from; the; rich'slag soasto obtain asa nal:product;,a1slag= impoverishein. nickel.- and/or copper. Thus; smeltingt .nickeliierous pyrrhotite in' the presentiprocess...servesfatwoffold purpose: (lite clean.`

containing copper-rich minerals and/or nickelrich minerals and also containing pyrrhotite low in copper and/or nickel. The ore after comminution isiirst treated by otation and, if desired, by magnetic separation operations 3 to yield (1) a pyrrohotite concentrate I3 low in copper and/or nickel, (2) one or more highgrade sulfide concentrates I high in copper and/or nickel, (3) one or more other concentrates 5 for treatment by other processes, and (4) a reject gangue tailing 4. The'high-grade nickel concentrate I0, e. g., a concentrate containing about to about 75% pentlandite and the balance mainly pyrrhotite, or a high-grade taining about 75% to about 95% chalcopyrite and the balance mainly pyrrhotite, and the iron-rich concentrate I3, e. g., a concentrate containing about 80% to about 95% pyrrhotite, are dried in operations 6 and 1, respectively, to a moisture content of less than about 0.5% free moisture, preferably less than about 0.25% free moisture.

If the concentrate is too coarse, it isl further comminuted. For best results, the concentrat-e is preferably at least about 95% minus 65 mesh and about 50% minus 200 mesh. The suldes must be fine enough and must remain in suspension for sufficient time to react with substantially all the oxygen present. On the other hand, too iine a particle size causes excessive dust losses. Satisfactory operation is obtained when smelting concentrates of the recommended particle size range in furnaces of the shape and size disclosed hereinafter. If the particle size of the siliceous flux and the highgrade concentrate are such that they settle to the furnace hearth at approximately the same rate, the slag being formed in various parts of the furnace will have a substantially uniform composition. An advantage of utilizing concentrated oxygen rather than pre-heated air for autogenous flash smelting lies in the smaller volumes of gases involved and in the facilitated control of furnace temperature which it permits. Such temperature control is important, both from the viewpoint of product temperatures and for the purpose of minimizing furnace accretions.

Thus, a preferred embodiment of the invention illustrated in Fig. 1 is a cyclic process involving, first, the autogenous smelting of highgrade sulfide concentrate Ill rich in nickel and/or copper to produce molten, high-grade matte 23 and molten slag 24 rich in nickel and/or copper; second, the tapping of said high-grade matte only; third, the autogenous smelting of pyrrhotite concentrate I3 to shower molten, lowgrade matte and molten, low-grade slag on the rich slag from which the iron-rich matte removes the major portion of the nickel and/or copper values to produce a low-grade slag; and fourth, the tapping of the impoverished, lowgrade slag and, if desired, the tapping of the low-grade matte containing the nickel and/or copper values recovered from the high-grade slag. Satisfactory results are also obtained when the high-grade matte is allowed to remain in the furnace during at least a portion of the slag-cleaning part of the cycle.

More specifically, the embodiment illustrated by Fig. 1 involves intimately mixing the dry, iinely-divided, high-grade concentrate I0 with a fluxing agent II such as quartzite or sand, to which may be added some lime or other fluxmodifying agent I2 if required. The controlled mixing of the .sulfide concentrate and the flux,

with or without a flux-modifying agent, is accomplished by means of feeders, mixer I1, and a sealing feeder I8 to eliminate uncontrolled passage of air. When it is attempted to autogenously smelt a charge of the aforementioned composition using relatively pure silica flux, e. g., quartzite containing about 95% silica, without a modifying agent and at normal operating temperatures, a metallurgically unsatisfactory slag is usually produced and detrimental solid accretions tend to accumulate in the furnace 22. However, addition of iiux-modifying agents I2 and i5, such as lime, magnesia or alumina, to the iiux may be omitted if a siliceous flux is chosen which already contains suitable modifying agents. quartzite flux may require the addition of as much as 10% lime or even more, a sand containing, for instance, only about silica and the balance mainly alumina, lime and other oxides, requires little or no additional modifying agents. The neness of the siliceous flux is about minus 48 mesh and the free-moisture content is less than about 0.5%, preferably less than about 0.25%. The ratio of flux to sulfide concentrate on a weight basis is based on the silica content of the flux, the grade of matte product desired, and the production of a metallurgically suitable slag. A suitable slag normally contains about 30% to about 35% silica. In the autogenous smelting of nickel-rich pentlandite concentrates or copper-rich chalcopyrite concentrates, the weight of lux amounts to between about 15% and about 40% by weight of the sulfide concentrate.

The sulfide-iiux-oxygen mixture is injected through one or more burners 2I into a reverberatory-type furnace 22 at a furnace temperature above about 1500 F., preferably between about 2100 F. and about 2300 F., by means of a gas containing more than about 65% free oxygen, preferably a commercially-pure concentrated oxygen containing about to about 98% free oxygen, delivered under pressure by pipeline 20 from an oxygen plant. 'I'he burners for injecting the sulde-flux-oxygen mixture into the furnace are similar in operating principle to con- Ventional pulverized-coal burners and are proportioned to impart a.velocity of about 50 to about 100 feet per second to said mixture. The furnace is similar in shape to, but only about one-quarter the volume of, conventional reverberatory smelting furnaces per unit of solid feed rate. The burner or burners are located in the end wall-and are directed in a substantially horizontal direction. A slightly downward inclination of the burner has been found valuable in avoiding the formation of accretions on the furnace bottom.

A suiiicient proportion of free oxygen is used to yield a matte 23 containing between about 15% and about 65% total copper and nickel. The oxygen necessary to promote the reaction to the desired degree of oxidation and to obtain the desired furnace temperature is broadly between about 15% and about 35% by Weight of the sulfide concentrate and is controlled by a valvemetering device 25. When smelting concentrates in the normal otation size range, the free oxygen present is almost entirely consumed. The molten matte 23 and the slag 24 are at temperatures within the range of about 2000 F. to about 2300" F. Autogenous smelting under the foregoing.conditionsusually produces rich slag 24 containingV about 30% Yto aboutl 35% silica Thus, while a silica-.

ing example is given, illustrative of the embodiment shown by Fig. 1:

A copper-nickel-iron sulfide ore, of the type occurring near Sudbury, Ontario, Canada, is treated by flotation and by magnetic separation to yield (l) a reject gangue tailing; (2) aY nickeliferous pyrrhotite concentrate containing about 0.05% copper, about 0.90% nickel, about siliceous gangue and the balance iron and sulfur; (3) one or more nickel concentrates containing about 0.5% to about 1.5% copper, about 3% to about 20% nickel and the balance mainly iron, sulfur and silceous gangue; Y and finally (4) a copper sulfide concentrate containing about 30% copper, about 1% nickel, about 3% siliceous gangue and the balance mainly iron and sulfur. The copper sulfide flotation concentrate is filtered, dried to a moisture content of less than about 0.5% and comminuted to substantially all minus 65 mesh by milling in closed circuit vvith an air classifier. Siliceous flux and lime are dried to less than about 0.5% free moisture content and are comminuted to minus 48 mesh.

The dried, finely-divided, copper sulde concentrate and fluxes are fed from bins at care-- fully controlled rates, mixed, and then fed to a burner of the type mentioned hereinbefore. Commercially pure oxygen, containing about 95% oxygen, carries the mixed, finely-divided solids through the burners into the hot flashsmelting furnace where iron and sulfur in the sulfide concentrate are burned in suspension in the oxygen to form iron oxides and sulfur dioxide. The iron oxides, vsiliceous ux and lime combine to form a fiuid slag. This combination occurs partly while the material is still in suspension and is completed after it settles by gravity to the furnace hearth. The unburned, or partly burned, sulfides settle upon the hearth and form a molten matte layer beneath the slag.

After a period of time, smelting of the copper concentrate is discontinued, matte is tapped, and then smelting of the aforementioned pyrrhotite concentrate is commenced, using a procedure parallel to that described for the copper concentrate. After smelting pyrrhotite for a period of time about '15% to about 30% aslong as the time during which lthe copper concentrate was smelted, slag is skimmed and the 4-part cycle is then repeated.

The sulfur dioxide gas passes from the furnace to the settling chamber, together with gaseous impurities present in the commercial oxygen and dust which amounts to about 5% of the solids charged into the furnace. Exit gas from the settlinnr chamber, containing about 1% of the v furnace solid charge, is then cleaned `by passage through an open spray tower, a wet cyclone, mineral fibre bags, and finally a wetCottrell. The dust leaving the wetA cyclone amounts to less than 0.05% of the furnace solid charge. The greater part of the SO2 in the gas is then liquefied by methods known in the art.

The proportion of oxygen to sulfides is adjusted to yield a matte containing about 55% to about total copper and nickel. The weight of oxygen used is about v25% to about 35% of that of the copper sulde concentrate smelted. The proportion of siliceous iiux used is about 25% to about 35% of the copper sulfide concentrate and is sufficient to form slag containing about 31% to about 33% silica. v

SpecificY average results obtained over a representative one-week period of continuous testing 10 using the foregoing combination of operations are as follows:

Copper sulfide concentrate, averaging 30.6% Cu, 1.1% Ni, 33% S and 1.8% SiOz, was fiash smelted as described above using as flux sand amounting to 33.1% by Weight of the copper sulfide concentrate. 'The sand contained 80% silica, and 5% of lime was added thereto. The amount of oxygen used amounted to 33% of the concentrate smelted. After each 6 hours of this first operation, matte averaging 57.65% Cu and 2.03%

Ni was tapped (second operation). The slag produced by the above operation contained about 0.90% Cu and about 0.15% Ni. 'I'he copper sulfide concentrate smelting was then discontinued and low copper pyrrhotite concentrate averaging about 1% Ni, 57% Fe,A 35% S and 2%' SiOz was then fiash smelted (third operation), using approximately the same ratio of fiux and oxygen as was usedin smelting the copper sulfide cone centrate. This operation was continued for 1 hour and provided a shower of low-grade matte and slag droplets. The matte droplets removed a large proportion of the copper and nickel from the slag to the underlying low-grade matte. The pyrrhotite used in this cycle amounted to 30% of the copper sulfide concentrate smelted. At the end of this operation, slag averaging 0.35% Cu, 0.16% Ni and 34.8% Si02 was skimmed (fourth operation). This cycle was then repeated.

Treatment of several thousand tons of copper sulfide concentrate and of nickel sulfide concentrate by the foregoing process showed that cost of the oxygen required to flash-smelt the various concentrates was about one-half that of the cost of the coal which would have been-required to smelt the same material by conventional meth-l ods.y Furthermore, refractory consumption was reasonable and was indicated to be less than in conventional practice. The furnace exit gas contained sulfur dioxide by volume and was cleaned, condensed by compression and cooling, and the resulting liquid sulfur dioxide used successfully in the commercial production of sulte wood pulp. Smelting of copper sulfide concentrate of the same composition by conventional coal-fired reverberatory furnace practice under similar conditions would yield matter of much lower grade without significant compensation in lower slag loss. Data averaged from fiash-smelting of nickel sulfide concentrate are as follows: Nickel concentrate, averaging 1.88% Cu, 11.95% Ni,.was flash-smelted using as fiux about 20% by weight of quartzite together with 2.5% by weight of lime. The amount of oxygen used amounted to 26.5% rby weight of'suldes smelted. After each 6 hours of operation, the matte averaging 6.95% Cu and 33.77% Ni was tapped, the nickel sulfide concentrate smelting was discontinued, Aand pyrrhotite concentrate averaging 1.25% Ni was flash smelted using approximately the same ratio of fiux and oxygen as was used in the smelting of the nickel sulfide concentrate. This operation sprayed low-grade matte and slag intol the rich slag (containing about 0.15% Cu and 0.60% Ni) already in the furnace; and copper and nickel were removed from the slag layer into the under- Y lying matte, thus decreasing the loss of valuable metal in the slag. After 2 hours of this latter operation, the slag, averaging 0.12% zCu, 0.30% Ni and 32.3% SiO2, was skimmed. The cycle was then repeated. Y Y 'v Furnaces employed for flash smelting'by the lpresent process differ in several respects from YITI conventional reverberatory furnaces.- Surfaces exposed to the name are constructedifor example, of hard-burned -br-iclrrich'in ymagnesia andrare backed by heat 'insulating material'. An: impermeable shell",r foriinstanceg-sheet steel',` normally'l entirely encloses' v'the furnacefapart from the `necessary openings lfo'r' the burners and -for withdrawing m'atteyslag,` and gasess This im= permeable casinghas beenffound necessaryto avoid, on theone hand, leakageoffconcentrated sulfur dioxide gas -iromlth'e furnace, or,v onthe other hand;y infiltration-lof air with" a resulting loss in thermal 'eiciencyand a` lowering 'in concentration ofv the-sulfur dioxide in the'exit gases. WeA have found that -a -furnaceinside volume of approximately Sito-16cm ft. is requiredper ton of cold chargef'smelted per day. This isonly aboutone-quarterth'e volume orar-conventional reverberatoryfurnaceof similar smelting capacity.v While some variation inthis' facton vcan be accomplished byadj'ustment iny the/thermal insulation of the iur-naceran'd' in 'the proportion of= inert material added;v such as fux; any @wide deviation from* thefforegoing furnace A'volume range willv result either vin: excessive `fheat loss if the furnace-istoo largeforin rapidfailure-oi the refractories if thefurnaceisf-toofsmall 'Burners for introduction of thefmixturefofsulfide, ux and oxygen are proportioned' to yield? a' velocity to said mixture ofi r`about "50to f1100` feet per:l second;` When oxygenated airis used `in'place of commercially fpure oxygen; the-burner exitvelocityf may be less than' that imentionedfbefcre:

In the presentY Y specification t andappended claims -where ltherterm highs-grade 'is f used in connection withY matta s'lag or` tconcentrate itismeant thereby that said-"matte, slagor. concentrate `is relatively lrich'in niolqeland/ or copper, e: g., thematte contains atl-least? about'v 15% total nickel and/orA copper, 'the concentrate kcon-'- tains at least-about?) totalini'clcel and/or copper, andthe .slag contains at' leastf about i055 nickel and/or copper, respectively:v Converselyywhere the term -low-grade"is used in connectionJwith matte;' slag or"`concentrate;. it is Imeant thereby that said" matte;v slag 'or concentratefis poor'inI-nickel and/or copper; e; g., the' matte, concentrate-and slag: contain;v respectively; less than the aforementionedamountsrof 'copperand/ or f nickel. In the '-'appen'dedfv claims, 1 where the termfniclrel and copper andnickel'copper Aare used-, it ismeant to :include cases wherether'product i described; such Aas =sulde vconcentrate 'from copper-nickel-ores or'matte'; vcontains upftorabout lllftimes asfmuch of. one fofthese metals-ias .of theother.` Where-'the term 4dnickeldis usedfthis is falsomeant toiincludefcobaltzV Although theA present inventionhas-been describedin conjunction. withcertainzpreferredfembodiments,` thereof,` thosef'sklled :intlie iart will understand" that variations. andi; modifications thereof canlbe made?" Suchvariationsand modi- *about-.o5 L73, a siliceous flux and an oxidizing SES containing-about 65%tof aboutA 98 free` oxygen to obtain a high-grade moltenfmattef containing aemajor fportion 'of-"copper, a high-grade .molten siliceousslag ric'hin copper, and a gas sufficiently richin' sulfur dioxide as -to be suitable for direct liquefaction bycompression; autogenously smeltingfaboveabout I2G00?? lik'a mixture of low-grade sulde concentrate lhaving a freey moisture content lessthan about-0.5% and containingabout toabout 95% pyrrhotite, asiliceous flux and an oxidizinggas `containingab'out 65% to about 98% freeoxygentofoxidize amajor portion of said low-grade concentrate to produce molten lowgrade matte, rich iniron sulde; and molten lowgrade slag; showeringsaid molten low-grade matteasmolten droplets-upon said high-grade molten siliceous slag tofpass through the same and to remove therefrom'the'bulk of the vcopper values to producean--enriched'mattm tapping at one point the high-grade matteprior to completion ofthe autogenoussmelting of the low-grade concentrate; tapping'atanother point impoverished slag' in such' manner 'that the-matteand slag are separately tapped in counter-current now-relative-'tol each other; and withdrawing from the space above'saidmoltenslag andv molten matte gas sufficiently rich iirsuliur dioxide Yas Yto be suitable for 'direct liquefactionby compression.

2. Animproved process'for producing a highgrade matte, a low-grade slag'anol gas sufciently richV in sulfurdioxde as to be'suitable for direct liqueiacti'on by1` compression' which comprises autogenouslysmelting'amixture of siliceous lux, an'oxidizinggas containingabout 65% to about 98% free oxygenand'a high-grade sulde concentrate containingl about '75% to about 95% chalcopyrite and having aifree moisture content of less thanabout0.5% in rvarefractory-linedv impermeably'encased chamber .being at a temperature 'aboveabout 2000215.; havingports for withdrawing matte and slag and..for'exhausting gas and)haying'at'leastl one burner for injecting said mixture to obtain a high-.grade moltenmatte rich in copper; a high-grade siliceous slag richincopper, and argas su'icientlyirich in sulfur dioxide as tobe suitable for direct liqueiaction by compression; 'autogenouslysmelting amixture of asiliceous flux, a low-grade sulde concentrate having a `free .moisture content. of less than about 0.5% and containing about'80% to about 95% pyrrhotite,4 and an oxidizing gas containing about 65% lto about 98%' free oxygen in amountssufrlcient to oxidi'ze about 4one-fourth to about twothirds by weight ofsaid low-grade concentrate by injecting tl1e..lowgrade mixture .into said chamberby meansof at least oneburner to `produce molten low-grade matte, richin iron sulde, andn low-.grade slag, said burner being directedto shower said molten low-grade matte in .the formof. molten ldroplets.upon-said high-grade molten siliceous-slag to pass Vthrough the same to remove therefrom the bulk ofthe coppervalues and'to producelanenrichedlnatteand an impoverishedslag; Ywithdrawing enrichedmatteand `impoverished slag; and withdrawing through` the gas exhaust port,gas suicientlyriclr in sulfur dioxide .as .to be suitable for direct liquefaction by compression.

3. An improved process forproducing a highgrade matte, low-grade slag and gassuiliciently rich in sulfur dioxideas'to'be suitable for direct liquefaction by compressionY which comprises autogenously smelting above about ()u F. a mixtureof highgrade sulfide concentrate containing' about"7r5'% torabout 95% chalcopyrite, a

13 siliceous flux and an oxidizing gas containing about 65% to about 98% of free oxygen to obtain a high-grade molten matte rich in copper, a highgrade molten siliceous slag rich in copper, and a gas sufficiently rich in sulfur dioxide as to be suitable for direct liquefaction by compression; autogenously smelting above about l500 F. a mixture of low-grade concentrate containing about 80% to about 95 pyrrhotite and at least one sulde of the group consisting of nickel sulfide and copper sulde, a siliceous ux and an oxidizing gas containing about 65% to about 98% free oxygen in an amount suiiicient to oxidize about one-fourth to about two-thirds by weight of said low-grade concentrate to produce molten lowgrade matte, rich in iron sulfide and low in at least one element of the group consisting of nickel and copper, and low-grade slag; showering said molten low-grade matte as droplets upon said high-grade molten siliceous slag to pass through the same and to remove therefrom the bulk of the nickel values tc produce an enriched matte and an impoverished slag; withdrawing enriched matte and impoverished slag; and withdrawing from the space above said molten slag and molten matte gas sumciently rich in sulfur dioxide as to be suitable for direct liquefaction by compression.

4. An improved process for producing a highgrade matte, low-grade slag and gas suiiiciently rich in sulfur dioxide as to be suitable fordirect liquefactionA by compression rwhich comprises autogenously smelting above about 2000 F. a mixture of substantially dry, finely-divided, highgrade sulde concentrate containing morethan 3% copper in the form of sulde and the balance essentially iron sulfide, a siliceous flux amounting to about 15% to about 40% by Weight of said high-grade concentrate and an oxidizing gas containing about 90% to about 98% free oxygen amounting to about 15% to about 35% by weight of said concentrate to obtain a high-grade molten matte rich in copper and a gas suiliciently rich in sulfur dioxide as to be suitable fordirect liquefaction by compression; autogenously smelting above about 2000 F. a mixture of substantially dry, finely divided, low-grade suliideconcentrate consisting essentially of iron sulde, a siliceous ux amounting to about 15% to 40% by weight of said low-grade concentrate and an oxidizing gas containing between about 90% to about 98% free oxygen in amounts suiicient to oxidize between about one-fourth to about twothirds by weight or said low-grade concentrate to produce molten low-grade matte, rich in iron sulfide, and low-grade slag; showering said molten low-grade matte as droplets upon said high-grade molten siliceous slag to pass through the same and to remove therefrom the bulk of the copper values to produce an enriched matte and an impoverished slag; withdrawing enriched matte and impoverished slag; and withdrawingfrom the space above said molten slag and molten matte gas sufciently rich in sulfur dioxide as to be suitable for direct liquefaction by compression.

5. An improved process for producing highgrade matte, low-grade slag, and gas sufliciently rich in sulfur dioxide as to be suitable for direct liquefaction by compression which comprises autogenously smelting above about 2000or F. a mixture of high-grade sulfide concentrate containing about 10% to about 75% pentlandite and having a free moisture content less than about 0.5%, a siliceous flux and an oxidizing gas containing about 65% to about 98% free oxygen to obtain a high-grade molten matte rich inv 14 nickel, a high-grade molten siliceousslag rich in nickel, and a gas suiiiciently rich in sulfur dioxide as to be suitable for direct liquefaction by compression; autogenously smelting above about 2000 F. a mixture of low-grade sulfide concentrate having a free moisture content less than about 0.5% and containing about to about 95% pyrrhotite, a siliceous iiux and an oxidizing gas containing about 65% to about 98% free oxygen in amounts sumcient to oxidize about one-fourth to about two-thirds by weight of said low-grade concentrate to produce molten lowgrade matte, rich in iron sulfide, and low-grade slag; showering said molten low-grade matte as molten droplets upon said high-grade molten siliceous slag to pass through the same and to remove therefrom the bulk ofthe nickel values to produce an enriched matte; tapping at one point the high-grade matte prior to completion of the autogenous smelting of the low-grade concentrate; tapping at another point impoverished slag in such manner that the matte and slag are separately tapped in countercurrent ow relative to each other; and withdrawing from the space above said molten slag and' molten matte gas suiciently rich in sulfur dioxide as to be suitable for direct liquefaction by compression.

6. An improved process for producing a highgrade matte, low-grade slag and gas sufciently rich in sulfur dioxide as to be suitable for direct liquefaction by compression which comprises autogenously smelting above about 1500" F. a mixture of high-grade sulfide concentrate containing about 10% to about 75% pentlandite, a siliceous Iiux and an oxidizing gas containing about 65% to about 98% free oxygen to obtain a high-grade molten matte rich in nickel, a highgrade molten siliceous slag rich in nickel, and a gas suiciently rich in sulfur dioxide as to be suitable for direct liquefaction by compression; autogenously smelting above about 1500 F. a mixture of a low-grade concentrate containing about 80% to about 95% pyrrhotite and at least one sulde of the group consisting'of nickel sulde and copper sulde, a siliceous flux and an oxidizing gas containing about 65% to about 98% free oxygen in an amount suicient to oxidize about one-fourth to about two-thirds by weight of said low-grade concentrate to produce molten low-grade matte, rich in iron sulde and low in at least one element of the group consisting of nickel and copper, and low-grade slag; showering said molten low-grade matte as droplets upon said high-grade molten siliceous slag to pass through the same and to remove therefrom the bulk of the nickel values to produce an enriched matte and an impoverished slag; withdrawing enriched matte and impoverished slag; and withdrawing from the space above said molten slag and molten matte gas sufficiently rich in sulfur dioxide as to be 'suitable for direct liquefaction by compression;

'7. An improved process for producing a highgrade matte, low-grade slag and gas sufliciently Vrich in sulfur dioxide as to be suitable for direct liquefaction by compression which comprises autogenously smelting above about 2000 F. a

mixture of substantiallydry, nely divided, highf grade sulfide concentrate containing more than 3% nickel in the form of sulfide and the balance essentially iron sulfide, a siliceous ilux amounting to about 15% to about 40% by weight of said high-grade concentrate and an oxidizing gas containing about to about 98% free oxygen amounting to rabout 15% to about 35% by weightf` of z said-concentrate to obtain i a .highgrade moltenzmatte-ricnfincnickeh ahhh-.grade moltencsiliceous:slaggriclr in ,-nickel, and -a gas suficientlyrich insuliursdioxideas to be suitable* for direct= liduefaction by compression; autogenously; smelting` above about 20009- r".A a mixture oi- .substantially dry, `iinely f divided, lowgrade @sulfide concentrate consisting essentially of iron sulfide, asiliceousflux amounting to about to140% by weight-ofsaidffloW-grade concentrate -and anroxidizingl gas containing between about 90% toabout=98% free oxygen. in amounts suicient to oxidize between4 about one-fourth to about two-thirds by weight of said low-grade concentrate tozproduce molten loW-gradematte, richain iron-sulfide, andzlow-grade slag; showering said molten;A low-gradematte as droplets upon saidhigh-grade;molten'siliceous slag to'pass through the, same and. to removethereirom the bullo-ofl the-'nickel-values tozproduce an enriched matte' and 1any impoverished slag Y withdrawing enriched matte and'` impoverished slag; and withdrawing-from-the- Vspace abovev said molten slag-"and moltenrzmatte gas suiiiciently rich .in sulfur dioxide `as tobe suitable for-direct lliquefactionr by compression.V

8. ern-improved processior-'produoing a highgradefmatte; low-gradc-slag andi gas suiieiently rich rin sulfur-dioxide-as ytobesuitable for direct liquefaction bye-impression which comprisesautogenously .smelting above-about 2000" F; e *c :rture ofsiliceous fiumian oxidizing gas conta ning about 65 fitto about 98% ireeoxygen, and a highgrade metalv sulde' concentrate comprising at least one sulfide 'selectedfron'i thegr-oup consisting of copper sulfide. andrnicliel 'suliide `and the balance essentially ironfandisulfnrxin the form of sulfide, said copper sulfidecorrespondihg to a concentrate having 'betweenlzabout750/21 to about chalcopyrite and said nickel 'sulde `corresponding to a concentrate-having between aboutl and about'75% pentlandite,v to cbt-aina high-grade molten matte rich in at least one metal of the group consistingfofnickel andcopper; a grade molten -siliceous slag rich in at least one metal of the group consisting of nichel and copper and a gas suicientlyrich in vsulfur dioxide as to be suitable for direct liquefaction by compression; autogenously smelting above about 2000 E a mixture of 'a siliceous flux, a low-grade sulfide concentrate containing about'80% to about '95% pyrrhotit'e and an oxidizing gas containing between about 65% to about 98%free oxygen in an amount sufficient to -oxidize between about onefourth to about two-thirds by weight of said lou-- grade concentrate to yproduce moli? matte, richl in iron sulfide; and i showering said 'molten lw-gradexnt. te as droplets upon said high-grade molten siliceous slag to pass'through the same-and to remove therefrom-the 'buik of vthenietal values from the s consisting of nickel and copper to produce an enrichedA matte and; an impoverished slag; withdrawing enriched matte and impoverished slag; and withdrawing from the space above said molten slag-and molten matte gas-suniciently rich in sulfury dioxide as to be suitable for direct liquefaction by compression.

9. An improved processforproducing a highgrade matte, low-grade slag and gas sufficiently rich in sulfur dioxide-as toV be suitable for direct 1iduefaction by compression which comprises autogenously smeltingV a mixture of -siliceous flux, anv oxidizing' gas containing about 65% toabout 98% free oxygen and a -high-grademetal sulfide concentrate comprising, atr .least v onev suliide fsclected from the groupconsisting of copper. sulndc and nichel sulide and the balanceessentially `iron and sulfur in the :forni of sulfide, said copper sulde corresponding to a concentrate having between about to about 95% chaicopyiteand said nickel sulfide corresponding to a concentrate having between about 10% and about 75% pentlandite, in a refractory-lined iinpermeably encased chamber being at a temperature above about 1500" F., having ports for withdrawing matte and slag and for exhausting gas and having at least one burner Afor injecting said mixture to obtain a high-grade molten matte rich in at least one metal of the group consisting of nichel andY copper, aihigh-grade molten siliccous slag rich in at least one metal of the group consisting of nickel and copper and gas suiiiciently rich in sulfur dioxideas to be suitable for direct liquefaction by compression; autogenously smelting a low-grade mixture of siliceous flux, a lowgrade sulfide cono-entrate consisting essentially of iron sulde, and an oxidizing containing about 65% to about 98% free oxygen to oxidize between about one-fourth to about two-thirds by weight of said low-grade concentrate by injecting said low-grade mixture into said chamber by means of at least one burner to produce molten .low-grade matte, rich; in iron suliide, and lowgrade slag, said burner being directed to shower molten matte inthe form .of moltendroplets upon said high-grade molten. siliceous` slag to pass through the-same and. to remove therefrom the bulk, of the metal valuesfrom the group consisting of nickel and :copper toproduce an enriched matte and an impoverished slag; withdrawing enriched matte Aand impoverished slag; and withdrawing through the-gas exhaust port gas sufficiently rich in sulfur dioxide as to-be suitable for direct liquefaction by compression.

10. An improved process for producing a highgrade matte, low-grade slag and gas'suliciently rich in sulfur dioxide kas to be suitable for direct lio'uefaction by compression which comprises autogenouslysmeltinga mixture of siliceous dus', an oxidizing gas containing more than about 65% free oxygen; and high-grade metal sulfide concentrate containing more than 3% of at least one elementA from the group consisting of. nickel and copper and the balance essentially iron and sulfur inthe form of sulde-to obtain a high-grade molten. matte rich in at least Ione metal of the group consisting ofnickel and copper, a highgrade molten siliceous #slag rich in at least one metal of the group consisting of .nickel and copper andra gas suicientlyrich in sulfur dioxide as to be suitable for direct liquefaction by cornpression; autogenously smelting a. mixture of low-grade sulfide concentrate consisting essentially of iron suliide, a siliceous uxlvand an osidizing gas containingrmore than about S5 free oxygen in an amount. suicientto oxidize about one-fourth to about two-thirds by weight oi said low-grade concentrate to produce molten lowgrade matte, rich in iron sulfide, and low-grade slag; showering said molten low-grado matte as droplets upon said high-grade molten siiceous slag to pass through the same and to remove therefromthe bull; of the metal values :from the group consisting of nickell and copper to an enriched matte and' an impoverished slag; withdrawing-` enriched matte and improverished slag; and Withdrawingfrom Athe vspace'above said ymolten slaglandA molten matte-gas sufficiently rich in sulfur dioxide as to be suitable for direct Number liquefacton by compression. 948,468 JAMES ROYCROFT GORDON. gg GEORGE HUGH CHARLES NORMAN. 5 1416262 PAUL ETIENNE QUENEAU. 1650907 WILLIAM KELVIN SPROULE. 1729408 CHARLES EDWARD YOUNG. 1,850,025 References cited in the me of this patent 10 gfggg UNITED STATES PATENTS 11958581 Number Name Date 2,035,016 '782,123 Garretson Feb. 7, 1905 2,221,620 900,466 Baggaley Oct. 6, 1908 2,510,352

18 Name Date Fink Feb. 8, 1910 Klepnger et al Dec. 21, 1915 Cavers Mar. 12, 1918 Butler et al May 16, 1922 Prince Nov. 29, 1927 Wagstai Sept. 24, 1929 McGregor Mar. 15, 1932 Krejc June 27, 1933 Bacon et a1 Jan. 2, 1934 Kennicott May 15, 1934 Smcox et a1 Mar. 24, 1936 Wagsta Nov. 12, 1940 Sklenar June 6, 1950

Claims (1)

10. AN IMPROVED PROCESS FOR PRODUCING A HIGHGRADE MATTE, LOW-GRADE SLAG AND GAS SUFFICIENTLY RICH IN SULFUR DIOXIDE AS TO BE SUITABLE FOR DIRECT LIQUEFACTION BY COMPRESSION WHICH COMPRISES AUTOGENOUSLY SMELTING A MIXTURE OF THE SILICEOUS FLUX, AN OXIDIZING GAS CONTAINING MORE THAN ABOUT 65% FREE OXYGEN AND HIGH-GRADE METAL SULFIDE CONCENTRATE CONTAINING MORE THAN 30% OF AT LEAST ONE ELEMENT FROM THE GROUP CONSISTING OF NICKEL AND COPPER AND THE BALANCE ESSENTIALLY IRON AND SULFUR IN THE FORM OF SULFIDE TO OBTAIN A HIGH-GRADE MOLTEN MATTE RICH IN AT LEAST ONE METAL OF THE GROUP CONSISTING OF NICKEL AND COPPER, A HIGHGRADE MOLTEN SILICEOUS SLAG RICH IN AT LEAST ONE METAL OF THE GROUP CONSISTING OF NICKEL AND COPPER AND A GAS SUFFICIENTLY RICH IN SULFUR DIOXIDE AS TO BE SUITABLE FOR DIRECT LIQUEFACTION BY COMPRESSION; AUTOGENOUSLY SMELTING A MXITURE OF LOW-GRADE SULFIDE CONCENTRATE CONSISTING ESSENTIALLY OF IRON SULFIDE, A SILICEOUS FLUX AND AN OXIDIZING GAS CONTAINING MORE THAN ABOUT 65% FREE OXYGEN IN AN AMOUNT SUFFICIENT TO OXIDIZE ABOUT ONE-FOURTH TO ABOUT TWO-THIRDS BY WEIGHT OF SAID LOW-GRADE CONCENTRATE TO PRODUCE MOLTEN LOW-

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