CA1086960A - Method and apparatus for complex continuous processing of polymetallic raw materials - Google Patents

Abstract

Abstract of the Disclosure Starting materials, e.g., copper-zinc or copper-lead--zinc concentrates and also slag-containing zinc and lead, are first melted in an atmosphere of gas containing free oxygen, and the resulting melt is then reduced by means of a gaseous plasma jet formed, for instance, by nitrogen.
An apparatus includes one or several plasmatrons whose nozzles are immersed in the melt at a angle to its surface for agitation of said melt by the plasma jet and for reduc-tion of the metal oxides.

Description

69~;0 The present in~ention relates -to processes and s~stems used in non-~errous metallurgy, and more speci~icallg, to methods ~or complex processing o~ pol~metallic materials, such as copper-zinc and coppe:r-lead-zinc concen-trates, slags con~aining zinc and lead, and also metallurgy products con--taining leads7 zinc, antimo~y and other volatile components.
The invention also relates to an apparatus ~or carr~ing out the above method.
~ he method according to the prese~-t invention makes it possible to process polymetallic materials and obtain a high yield o~ metals.
Known in the art are various methods of processing cop-per and polymetallic concentrates. ~or example, there is known a method ~or processing ores and concentr~tes contain-ing non-ferrous and rare metals (cf. US Pat. No. ~,555a164; :
Brit. PatO ~o. 1,186,088; Canad. Pat~ ~o. 869,477; and Swed.
Pat~ ~o.335,232).
According to tihe known methods, the materlal being pro-cessed and ox~gen are ~ed into a c~clone chambex wherein oxi-dizing, melting and partial sublimation of volatile metals take place and where~rom the molten materials is directed into an electrothermic ~urnace, with some o~ the non-~errous metals within the melt beingr processed therein.
~ his method does not provide ~or sublima-tion o~ zinc a-t a rate over 0.5 kg o~ zinc per 1 m~ o~ melt per min, which makes it necessar~ to use a large-area electrothermic ~urnaco.
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, ~ is results in higher hest losses, hence in higher spaci-fic power consumption.
~ he melti~g chamber and the furnace are separated with a cooled partition wall which prevents sulphur dioxide ~rom getting in*o the electrot~errLIic furnace~
~ he furnace is provided with a condenser ~or vapours oE :
metals which are sublimated during the electrothermic treat-ment of slag, O~idic materials poor in sulphur are processed with the addition o~ liquid or solid fuel.
~ here are also known various methods o~ processing poly-metallic materials and zinc slags by fu~ing ~or extraction of the metal~ contained therein.
Such, for instance, are methods, for fuming slags with the use o~ liquid fuel (cf. ~rit. Pat. l~o~ 1,161~164 and ~ulg. Pat. 24,366 /No. 138/).
~ his method consists in fuming liquid ~uel under a pres-sure oE no-t lower than 15 a-tm, mixing it wi-th air and injeot-ing the resultant mixture into the slag being processed. ~he method is used for laad, tin, and copper slags~ Also is known blasting o:E liquid slag with gaseous reducing compounds~
formed in -t~e burning of a mixture of li~uid ~uel and air (cf. Canad~ Pat. No, 8~2,278).
~ h~ r~te oE zinc sublimation amounts here to 1 -5 kg per m3 o-~ melt per minute.

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This method does not provide ~or processing o~ slags from old slag dumps. ~he process ~eatures emission of a large volume of` gases which~ to be ~ull~ u-tilized, will require construction of boiler plants and ~iltering ba~s. Besides~
this method is in-termi-ttent rather than con~inuous~
In addition, there is known a method ~or the electro-thermic processi~g o~ slags (c:~. US~X I~ventor's Certi~icate No. 145,755)-Here, initial dump slags are melked at a -temperature ranging -~rom 1,350 to 1,400C, with 3- 5% o~ reducing agent, 10- 15% of pyritic concentrate and 10~ of lime stone being added therein. In the process o~ melting~ copper and noble ~-metals go into a low-copper matte, while zinc, cadmium and rare metals æublimate.
~ his method allows a zinc sublimation rate o~ not over 1 kg per 1 m per min~
It is there~ore an object o~ the present in~ention to provide a method -~or complex continuous processing of poly~e-tallic materials which allows su~idic and oæidic materials to be melted in a most ef~icient way.
A¢cording to the present in~ention9 sulphidic copper-zinc concentrates can be sub~ected to autogenous melting by burning part of sulphur out o~ the sulphides in ~lame or a c~clone in an atmosphere o~ oxygen or air enriched by oxygen, which re-sults in obtaining a gas rich in sulphur dioxide7 a matte rich in copperj and a slag which contain~ zinc.

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~86g60 With the gas chamber and the metal bat~ of a furnace being separated with a partition wall, the zinc slag obtai-ned is blasted with a low-temperature plasma jet, which ma-kes it possible to effect reduction at a high speed compara- ;
ble with the speed of -the flame melting of the initial mate-rial and to conden~e the zinc vapours obtained in the ~orm of li~uid metal or oxidized sublimation products.
In processing oxidic materials7 e.g " zinc slags, the melting thereo~ can be e~ected in a melting chamber p~vi-ded with electrodes li~e an ore-melting ~urnace, in a neut-ral or slightly oxidizing medium which excludes -the reduction or sublimation of zinc. Here, the input electric energy is used entirely for melting slag, which makes ~or higher speci-~~ic output o~ the smelting chamber and lower specific power consumptîon. ~he melting chamber need not be separated from other parts o~ the furnaoe installation, which simpli~ies the equipment and maintenance thereo~. ~he zinc present in the melt is sublimated in the second chamber o~ the installation under the action o~ a plasma jet in a reducing atmosphere like in melting sulphidic materials.
Another object o~ the present invention is to bring a reducing plasma jet in close co~tact with the melt contai~ing`-~oxides, whereby reduction o~ the component metals is stepped up. Since the reduction is additionaly retarded by the di~fu-sive character o~ the process, the agitation o~ the melt pro-duced by the plasma jet eliminate~ the di~usive retardation and sharply increases the rate o~ reduction.
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. ~ , ~8~g~0 Still another object o~ -the present in~ention is to speed up drasticall~ the reduction oE zinc oxide and to re-move the metal ~apours bei~g formed from the melt through natural con~ersion of native gas with a plasma je-t in combi-nation with air or ox~gen, said conversion being accompanied by the ~ormation of carbon and hydrogen oxides which are especially active thereupon.
A further object o-~ the present invention i8 to use a nitrogenous plasma jet for agitating the slag bath, ~or eli-minating diEfusive resistance therein, and also for accele-rating the sublimation of zinc.
Yet another object o-E the present i~vention is to use a la~er oE coke on the surface oE said bath as an active deoxidizer for the slag that is ejected by the plasma jet into the gas chamber and is spread ever the coke's surface.
The low consumption oE co~e (strictl-~ stoichiometric accord-ing to the reaction ZnO ~ C~Z~ ~ Co) and a simple charging thereoE on -the bath sur~ace make its use in -the process ver~
efficient.
A Eurther object o-E the present invention is to carr~
out processing in an apparatus oE minimum size and, accord-ingly, with mini~um thermal losses, making it possible to achieve the re~uired result~ -that is, -to melt -the material, to obtain gases rich in sulphur dioxide~ to sublimate zinc and to condense the vapours in the ~orm o:E liquid metal ot oxidized sublimations.

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Autogenous m~lting of sulphides enables ade~uate over-hea-tiIlg o~ the melt~ which reduces power consumption. ~he over-heating ~elt does not cool down during flow-overs~
while such cooling is inevitable where separat~ installa-tions are in use.
~ he resulting zinc vapours travel the shortest wa~ to arrive at the condenser, which makes for be-t-ter condensation and reduces the amount of return products.
A sublimation chamber of the apparatus incorporates a device used to for~ a low--temperature plasma, with a nozzle thereof being immersed in -the melt~ which ensures injection of the plasma iet directly into the zone of reaction. In ad-dition7 the plasma je-t provides ~or -the required agi-tation of the melt, which, in turn, speeds up reducin~ reactions and intensi~ies -the process as a whole.
A ~urther object o~ the present invention is to deter-mine the optimum position of the device for ~orming a low-~tempera-ture plasma ~s regards e~ficient agitation -therewith and longer service li~e of the chamber walls.
Depending on -the viscosity of slag that is rela-ted to its composition and temperature, the device should be posi-tioned at different points of the bath. ~he position refer-red to hereinafter mee-ts this requirement.
A still fllrther object of the present invention is to provide an apparatus wherei~ the nozzl~ can be displaced verticallg and so submerged in the melt to various depths , .

6~60 with a view to changing the extent of agitation depending on the gas pressure, the melt viscos.ity, and the required extent of spraying the melt over the coke.
To accomplish these and other objects according to the present invention, there is provided a method for the com-plex continuous processing of polxmetallic materials, speci-fically, of copper-zinc composition, including two-stage suc-cessive processing, wherein the initial material is melted at the first stage, and the reducing melting thereof i5 carried out at the second ~tage; said method is characterized by the use of a gas containing free oxygen as the atmosphere wherein the initial material is melted, whereas the reducing treatment of the melt thus obtained is effected by means of a plasma flame with a temperature ranging from 4,000 to 5,000 C, while the temperature of the melt surface is maintained within the range of 1,500 to 1,600C.
More particularly, the invention relates to a method for continuously processing complex, non-ferrous metallic com-positions essentially of sulfides and oxides of zinc and metals selected from the group consisting essentially of copper, lead, antimony, and mixtures thereof, comprising-a) heating said composition under an inert or oxidizing atmosphere to form a melt, b) redu~ing said melt by means of a gaseous plasma jet at a temperature of about 4,000 to 5,000C, whiLe main-taining the temperature of said melt surface at about 1,500 to 1,600C.
I~is arrangement provides for most expedient pro-cessing of sulphidic and oxidic raw materials.
First~ in processing sulphidic copper-zinc concen-trates, these can be subjected to autogenous melting by burn-~. . .
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1a~8i9~i0 ing a part of sulphur out of the sulphides in a 1ame or a cyclone in an atmosphere of oxygen or air enriched with oxygen, which results in obtaining a gas rich in sulphur dioxide, a matte rich in copper, and a slag which contain~ zinc. With the gas chamber of a furnace installation and the metal bath there-of being separated with a partition wall, the zinc slag obtained J~.
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is blasted with a low--temperature plasma jet, which makes it possible to carr~ out the process o~ reduction at a high speed commensurable wi-th -the speed of melting the ini~ial ma-terial and -to condense the evolved zinc vapours in -the ~orm o~ uid metal or oxidized sublima-tes ~or ~urther hy-drometallurgical processing.
Second, in processing oxidic materials, e.g~, zinc slags, the melting -thereof can be e~ected in the melting chamber, provided with electrodes, o~ the oremelting furnace type, in a neutral or slig~htly oxidizing atmosphere~ whic~
precludes reduction or sublimation o~ zinc. The input elect-ric energy is used entirely ~or melting~ the sla~, which makes ~or higher specific output and lower specific power consump-tion. '~he mel-ting chamber need not be separa-ted ~rom other parts of the apparatus, which simpli~ies the construction and maintenance o~ the la-tter.
~ he zinc present in -the melt is sublimated in the seco~d chamber o~ the installation under the action o~ a plasma jet in a reducing a-tmosphere, like in melting sulphidic raw mate-rials.
According to an embodiment o~ the present in~ention, the method i5 characterized by blasting the melt with a plasma jet during the reducing melting and by agitating the melt to reduce the metal oxides present t~erein.
That makes it possible to bring -the reducing gas ~low into close contact with the mel-t con-taining oxides~ whereby , .
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the rnetal reduction is stepped up. Since the reduction is additionally retarded by -the diffusive character of the pro-cess 9 the agitation of the melt eliminates the diffusive retardation and sharpl~ accelerates the reduction.
According to another embodiment o~ the present in~en-tion, the method is characterized by the use of na-tive gas ~-as a plasma-forming agen~.
~ hat feature makes it possible, through the use of a natural conversion of native gas in-a plasma jet in combina-tion with air or oxygen, to utilize carbon and hydrogen oxi-des, which are especially active when formed, for reducing the metal oxides and to speed up drastically -the reduction of zinc oxide and the removal of the metal vapours being formed from the meltO
According to still another embodiment of the present invention, the method is characteriæed by the use of nitro-gen as a plasma-forming gas.
~ hat makes i-t possible to use the nitrogen produced as a by-product at ox~gen plants for bubbling the metal bath, for eliminating diffusive resistances therein, and for sharp-ly accelerating the sublimation of zinc.
According to a further embodiment of -the present inven-tion, -the method is characterized b~ the use of a la~er of coke which is formed on the surface of the melt in the pro-cess of reduction.
~ his makes it possible to use a -thin layer of coke on the surface o~ the bath as an active reducer for the streams ~ : -' ' ,' ' ':
': ' ' " , ' ,~ ' ' '; ' ' .~ ' ' 1~869160 o~ slag ejected in-to the gas chamber b~ the bubbling gas and spread over the coke's sur~ace. A low consumption of coke (strictly stoichiometric according to the reac~ion ZnD ~
Co ~ Zn ~ C02) and a simple charging thereo~ on the bath sur~ace makes its use in the process very e~ficient.
According to a~ot~er embodime~t o~ the present in~en-tion, there is provided an apparatus for carrying out the pro-posed method, which comprises a melting chamber ~or melting -the materials and metal oxides thereof, and a reducing-subli-mating chamber connected with the melting chamber which, in turn, is connected -throu~h a gas duc-t with a chamber ~or con-densing metal ~apours; -this appara-tus is characterized by the provision of at least one plasmatron built in-to the lining of said reducing-sublimating chamber with a nozzle being perma-nentl~ immersed in the melt ~or in~ecting a plasma jet the-reinto.
~ his makes it possible, with an apparatus o~ the minimum size and, correspondi~gly~ with minimum thermal losses, to attain the re~uired aim, that is, to melt the material, to obtain gases rich in sulphur dioxide, to sublimate zinc ~rom -the melt, and to condense -the vapours in the form o~ a liquid metal or powdery sublimates.
Autogenous melting o~ sulphides allows adequate overhea-ting of -the melt, which reduces power consumption by said plasmatron. '~he overheated melt does not cool down during ~low-overs, a~though that is inevitable where separate in-., . . . , , , , ~ , ~ ~ii36~

stallations are in use. ~h0 zinc vapours obtained travel theshor-test wa~ to the condense:r, which makes ~or be-tter conden-sation and reduces the amou~-t of return produc-ts.
~ he plasmatron incorpora-ted in the sublima-ting chamber with its nozzle i~mersed in -the melt ensures the injection of the plasma jet directly into the reaction zone. In addi-tion, the plasma jet ensures the necessary agita-tion o~ the mel-t, which~ in turn, makes for faster reducing reaction and intensi~ied process as a whole~
According to still another embodiment of the present invention, there is provided an apparatus characterized b~ ~-the use o~ one or several plasmatrons arranged in parallel which can be positionally adjus-ted with respect to the cham-ber walls and which are set up at an acute angle to the melt surface.
Th.s arrangement provides for the most advantageous position of the plasmatrons to be selected as regards the e~ficienc~ of melt agitation and longer service life of the chamber walls.
Depending on the viscosit~ of slag, related to i-ts CO~l-position and temperature 7 the plasmatron should be positioned at various different points of the bath.
~ he plasm~tron position referred to herein meets that re~uiremen-t.
In addi-tiona -there is provided an apparatus according to the present invention, characterized b~ a mechanism intro-' ' : ': .

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duced ~or mo~ing -the plasmatron nozzle within -the melt, agi~
tating the melt as this undergoes reduction, and -the subli-mating chamber being provided with means for charging co~e on the melt surface.
~ his makes it possible -I,o displace -the plasma-tron nozzle vertically9 imrnerse it in the melt to different depths ehang-ing -the exten-t of bubbling depending on -the gas pressure, the melt viseosity, and the re~uired extent o~ spraying the melt over the coke.
~ mbodiments of the present in~ention will now be descri-bed in greater detail by wa-y of example with reference to the accompanying drawings, wherein.
Fig. 1 illus-trates an installation for the complex con-tinuous processing of polymetallic materials with a p~rtition wall separating the gas space;
~ ig. 2 shows an apparatus for complex co~tinuous proees-sing of polymetallic materials with a ehannel connecting two melt zones;
~ ig~ 3 shows an apparatus for comple~ continuous proeess-ing of polymetallie materials wi-th a chamber for final burning of zinc vapours;
Fig. 4 shows an apparatus for complex eontinuous process-~ing of polymetallic materials with a melting c~clone;
Fig. 5 shows an apparatus ~or complex continuous process-ing of polymetallic materials with a mel-ting stack, according to an embodiment o~ the in~ention.

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~ he method ~or complex continuous processing o~ polyme-tallic sulphidic materials according to t~e prese~t i~vention consists in that a polymetallic sulphidic concentrate is melted in a cyclone or a stack in an ox~gen flow.
~ he sulphur-rich gases are separa-ted ~rom dust and -then used in the production o~ sulphuric acid or elemen-tary sul-phur.
~ he melt is separated in the rnelting chamber, according to speci~ic weights, into slag, matte, and metal~
~ he metal and matte are tapped from the mel-ting chamber, whereas the slag enters the second, sublimating, chamber, where it is agita-ted and its vola-tila compone~ts are reduced and sublimated under the action o~ a reducing plasma jet.
The sublimated vapours o~ the volatile metals arrive at the condenser where these are turned into a liquid metal or are burned to obtain oxidized subli~ates.
~ he plasma may be ~ormed by native gas or nitrogen. In the latter case, the sublimating chamber is charged with coke.~
In processing oxidic polymetallic raw materials or metal-lurgical sub-products, these are melted in the electrother-mic part o~ the apparatus; and the molten slag is then proces-sed similarly to polymetallic materials.
The method o~ processing polymetallic ma-terials accord-ing to the present i~e~tio~ makes it possible to melt sulphi-dic materials and sulphurless ores, concentrates~ and metal-lurgical sub-products.

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Sulphidic materials7 e.g., copper-zinc concen-trates, can be melted in an au-togenous mode or with -the addition o~
~uels in a vertical flame in a cyclone ~urnace. Oxidix mate-rials, e.gO, zinc-bearing slags, are melted in -the electro-thermic part o~ an appara-tus.
The mel-t obtained as described hereinbe-~ore en-ters the reducing chamber separa-ted by a partition wall ~rom the mel-ting chamber, where it is subjec-ted either -to -the reducing ~ction o~ a plasma jet or to the action o~ a nitrogen plasma ~or agitating the melt where it bears -the layer o~ coke.
According to ~ig. 1, the appara-tus includes a melting chamber 1, provided with devices 2 ~or charging solid mate-rials, and wi-th devices for melting the material being pro-cessed, e.g., electrodes 39 a gas duct 4 ~or removin~ gases ~rom the melting zone; holes 5 and 6 ~or tapping o~f matte and metal, respectively; and a partition wall 7, separating the chamber 1 ~rom a chamber 8, which is used to remove me-tals ~rom slag. ~he chamber 8 is provided with devices 9 to form a low--temperature plasma (plasmatrons), wi-th seals 10, devices 11 ~or charging coke, a hole 12 ~or tapping slag, and a gas duct 13, conrlectirlg the chamber 8 and a chamber 14 ~or condensing the metals removed ~rom -the slag. ~he chamber 14 is provided with spra~ing devices 15 and a gas duct 16.
In ano-ther embodime~t of the apparatus according to ~ig. 2, a chamber 17 is connec-ted with a cham~er 18 through a charmel 19.

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In the case where zinc is to be obtained in the ~orm o~ oxide? the apparatus is provided with a charQber 20 (as shown in ~ig. 3) ~or oxidizing the metal vapours removed from the slag. The chamber 20 can be mounted on rolls to compensate ~or its temperature expansion, as shown in Fig.3.
In processing sulphidic materials or other ma-terials containing ~uels suitable ~or autogenous burning or burning with the addition o~ fuels, the apparatus ca~ have~ as the device ~or mel-ting -the material being processed, a c~clon 22 (Fig. 4) with an ejector 23 for supplying a charge thereb~, or a stack 24 (Fig. 5~ with burners 25 used to burn and melt the charge.
~ he appara~us operates as ~ollows.
According to ~igs 1, 2, and 3, an oxidic material which contain no fuels9 e.g., a slag containing zi~c or other ~ola-tile metals, is charged through respective devices. ~he mate-~rial gets into the chamber 1, where it is melted with the aid of the electrodes, immersed in the slag, and then enters the chambex 8 where zinc is reduced and sublimated in the form of vapours under the actioIl of reducing gases prod~ced by the devices ~orming a low-temperature plasma. ~he vapours enter tur~
the condenser 14, where they are cooled, to a li~uid, where-~rcm zinc is tapped o~f as it accumulates.
Where a nitrogenous plasma is used, the chamber 8 (~ig. 1) is charged with coke which iB delivered to the melt sur~ace through the charging devices 2.

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~ he melted slag, poor in non-ferrous metals a~ter their extraction there~rom, is continuousl~ or periodically tapped from the chamber 8 -through the hole 12~ Where metal or matte are obtained, they are periodicall~ tapped of e, on accumula-tion, through th~ holes 6 and 5 of the chamber 1 ~ig. 1).
As it is possible to run the process in an e~acuated as well as non-reducting atmosphere wi-thin the chamber 1, the latter does not require sealing and the electrodes 3 may be left un~tightened in its rooe in this mode o~ operatio~. In this case, use can be made o~ electrodes that will spontane-ously weld with the metal ~urnace shell, which makes it pos-slble for the melting chamber to consume vir-tually any speci-eied power and thereb~ ensure the high output of melting.
The division of the installation into two zones, the melting and the sublimating ones, makes it possible to have in the first, larger, zone a melt temperature not higher than the ~using temperature for ths material being processed~ to work with a la~er o~ solid charge on the molten bath, and hence to reduce considerabl~ the melt-chamber's heat losses through the walls, -the hearth and the roof of the ~urnace.
~his results i~ lower specieic power consulnption.
~ e devices 9 for -the ~ormation of a low--temperature plasma allow ~or adjustment o e the power consumption, and O:e the flow rate, pressure, and temperature o~ re~lucing or neut-ral gases.

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Said devices 9 ~or the ~ormation o~ a low--temp~rature plasma can be mounted in-to -the walls o~ the chamber 8 as into its roo~ at right or acute angles to the melt sur~ace;
moreover, the~ can be shi~ted a-t an angle to each other in both vertical and horizontal planes. ~he nozzles o~ -the devi-ces 9 can be immersed in the melt -to di~-fere~t depth.
The devices 9 can be provided with suitable actuating mechanisms.
In order to prevent -the lining o~ the walls in the cham-bers 1 and 8 from wear, the partition wall and -the co~necting gas duct can be co~fered and cooled by water or other heat--trans~er agentæ.
~ he apparatus ~or processing o~ sulphidic concentrates according to Fig. 4 operates as follows.
A dried sulphidic concen-tra-te or other ~uels containing the necessar~ materials, are blown in alo~g with ~luxes thro-ugh the ejector 2~ o~ the c-~clon 22 b~ means o~ a jet o~ ox~
ge~ or air enriched by oxygen.
~ he charge is melted by one heat generated either b~ the exothermal reactions o~ sulphide oxidation or b~ the burning of the ~uel introduced into the c~clon. ~he molten charge ~;
then flows down the cyclon walls in-to the melting chamber 26.
The produced gases are remo~ed -through the gas duct ~or fur-ther processin~.
~ he melt entering -the chamber 26 strati~ies according to the speci-~ic weights o~ the compo~ents thereo~ the proces-. ,.... . , , . . : , .
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9~o sing o~ materials containing, ~or ins-tance, zinc, lead and copper, the metallic lead evolved settles on the chamber's hearth, the copper matte ~orms a layer directly above the lead, and the zinc-bearing slag forms the uppermost layer.
The melt depth is maintained such that the par-ti-tion wall 28 is permanently immersed in the la~er of the slag.
~his arrangement prevents -the gases in the chambers 26 and 29 ~rom mixing, but allows a ~ree exchange of the melt bet-ween these chambers.
As the lead and the ma-tte accumulate, they are periodi-cally tapped from the furnace through the holes 30 and 310 ~ he slag is tapped o~f through the hole 32 either conti-nuously or intermittently. Reduction takes place in -the cham- ~-ber 29.
~ he apparatus according -to ~ig. 5 operates as ~ollows.
~he charge is oxidized and melted by means o~ the vertical burner 25, mounted in the stack 24; the volatile metal~ are -~sublimated -through interaction of the slag melt with a reduc-ing low-tempera-ture plasma produced by the devices ~3 adapted for the ~ormation thereo~, or through the interaction o~ the slag melt, agitated with a nitrogenous low-temperature plasma,~
with the coke.
The reduced vapours are removed through the gas duct 34 either to -the condenser ~5, where the metal vapours are con-densed into liquid metals, or to the chamber 20 (~ig. 3), used for a-~terburning, where the metal vapours are oxidized.
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-- '19 --~he following examples illustrate the invention.
_ample 1 For processing of polymetallic concentrates, a copper--zinc concentrate containing sulphur (S), 7~ 25% of copper, and 7- 25~o Of zinc is dried to a moisture content o~ 0%, and is supplied to a bin placed beside -the furnace a-t a ra-te o~
one ton per hour. ~herefrom, -the concentrate with the addi-tion of crushed quarth is blown tangentially with a stream of oxygen, at a rate of` 200 m3 per ton of charge, by means of a burner tangentially into -the cyclone chamber or into a burner built i~to the stack. ~he gases that contain 75% of sulphur dioxide (S02) are used for making sulphuric acid, and -the mel-t of matte and slag stratify according to the specific weights of componen-ts. ~he matte settles on the bot-tom and is tapped off as it accumulates in excess o~ a 200 mm level. ~he slag forms the upper layer of the molten bath and enters the reducing-sublimating chamberg Here, the slag is blasted with a plasma jet and on accumulation, is intermit--tently tapped off through a hole located at 500 mr~ above the hearth. ~he overall level of the melt in the ~urnace is 700 -- 750 mm~
The vapours of zinc pass to the condenser, whose free volume is sprinkled with metal drops by an impeller from a zinc bath located at the bottom of the condenserO A constant temperature o-~ 500C is maintained in the condenser, which make~ for faster cooling of the vapours and prevent~ their oxidation by water steam and carbon oxide.

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`` 1~il8~9 E;~ -~ he sinc sublima-te can be oxidized in the charnber by -the air fed thereinto; the o~ides thus ob-tained can be col-lected in -the filtering bags a~ter cooling the gases.
Example 2 ~ or processing o-f zinc-bearing slags, granular ~lag ~rom old slag dumps containing 1 -1.5% of copper, up to 2~5%
o~ lead, and 8 -15% o* zinc is dired in a tube furnace and charged into the melting chamber o-f an electric furnace in-s-tallation (one ton per hour) heated tbrough electrodes im-mersed in slag. ~he furnace does no-t re~uire se~ling; the atmosphere therei~ is neutral. ~he melt bath level is up to 750 mm.
The mel-t enters the reducing-sublimating part o* -the installa-tion where it is acted upon by a plasma jet. With a nitrogenous plasma used, said part of the installation is charged with a crushed and dried coke. With natural gas being~
used, conversion thereo~ is accompanied by the emission o~
black carbon and hydrogen~- which serve -to reduce zinc oxide.
~ he zinc vapours are removed into the condenser or the burning chamber, whereas -the slag, as it accumulates, is tap-ped o~f t-hrough the corresponding hole.
Some other embodiments o-f the method are described below.
Example~. Meltin~ o~ a Pol~metallic Concentrate A copper-zinc concentrate containing from 5 to 25% 0 copper and :Erom 5 to 25~o o-f ~inc is mixed wi-th quartz ore containing 75% o* silica; the charge obtained is dried in a ... . . .. : .. . , . . , ~,, , . . .... , , :

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tube furnace to a moisture content o~ 1~o~ ~he dry charge is delivered through a pneumatic conveyor to a bin mounted over the furnace installation, where~rom the charge is directed by a feeding device into a tube at a rate o~ one ton per hour. ~`he tube receives a stream o~ ox~gen, at a rate of 200 m3 per ton of charge, to blow said charge into a cyclone.
Xere, the charge is melted, then ~lows down the cyclon walls into a melting chamber at 1,250 - 1,300C. ~he gases containing 75% of sulphurous anhydrode are removed through a water-cooled standpipe and electric ~ilters and are then used in admixture with other gases ~or making sulphuric acid.
In the melting chamber, the melt stra-ti-fies into a mat-te containing 50/0 o~ copper and a slag containing 10% of zinc, up to 1~o of copper, 20 - 25% of iron, and 30 - 35% o~
silica.
~ he slag ~ills the space behind the partition wall that ~orms the reducing-sublima-ting part o-~ the installation.
~ he plasma-trons immersed with their nozzles in the melt to a depth o~ down to 200 mm ensure the required agitation ;
of -the melt, the speci~ic rate o~ gas being 1.3 m3 per 1 m3 per min. ~he zinc content o~ the melt drops ~rom the initial value o~ 10% to 0.5 - 0.7%. ~he zinc is reduced at a rate of 1~ kg per 1 m3 per min. The reducing chamber is charged wit~ ;
coke i~ a~ounts o~ 1.5 - 2% of the slag weight.
The m~_~tuxe o~ vapours and gases,is injec-ted into the condenser, where the zinc vapour~ are condensed and the gases are burned.

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69~0 '~he gases can be compressed and used ~or heating purpo- -ses. ~he heating power thereof moun~s up to 3,000 large calo-ries for 1 m3. ;
With ni-trogen used as the plasma-~orming gas, -the yield - of zinc amounts to 80%; the r~mai~der is condensed and, as a -~
return product, goes bac~ to the charge ~or rnelting.
As the vapours are burned, the gases are cooled down through suction of air whose volume i5 10 - 15 times that of the gases.
The gases are separated ~rom dust in a filtering bag.
The dust obtained cont~i~s 65% o~ zinc and up to 12% o~ lead9 With the use of natural gas as the plasma-forming agent, it undergoes conversion in the plasmatron hence, no addition of coke to the melt is required since zinc is reduced with the adequate amounts of black carbon and hydrogen formed dur-ing said conversion.
~ he gas flow rate, the ~ield of fuels, and the process-ing of gases are similar to those described above, but the ~ield of metallic zinc is not over 75%, with t~e rest going ~
into return products. -Example 4. Meltin~ of Zinc-Bearin~ Sla~
A lead~-mel-ting slag, con-taining up to 1~5Yo of copper, 15% of zinc, up to 2~o 0~ lead, 23 - 25% Of iron, 20 - 25~o of silica, and up to 20% o~ calcium oxide is dried to a moisture conten-t of 0~5% -then charged into -the melting chamber of a 1,000 cVA electric furnace at a rate of one ton per hour.

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- 2~ -~ he f`urnace is provided with three electrodes. The melt obtained fill~ the space behind the partition wall and is subjected to the action of` a plasma with characteristics si-milar to those described above. The matte containing 20- 25%
of copper is separa-ted in the melting chamber of the furnace.
~he gases are separa-ted ~rom dus-t and are vented to the atmo-sphere.
~ he ~inal slag contains 0.5 ~ 1% o~ zinc9 0.1% of lead, and 0.3% o~ copper.
Condensation runs similarl~ to that taking place in the melting o~ concentrate~.

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Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for continuously processing complex, non-ferrous metallic compositions essentially of sulfides and oxides of zinc and metals selected from the group consisting essentially of copper, lead, antimony, and mixtures thereof, comprising:
a) heating said composition under an inert or oxidizing atmosphere to form a melt;
b) reducing said melt by means of a gaseous plasma jet at a temperature of about 4,000 to 5,000 C, while main-taining the temperature of said melt surface at about 1,500 to 1,600°C.

2. The method of claim 1, wherein said composition consists essentially of copper-zinc sulfidic concentrates, and wherein the heating of said composition is accomplished auto-genously by burning a portion of the sulfur from the sulfides, to produce a gas containing sulfur dioxide, a copper matte and a zinc-containing slag.

3. The method of claim 1, wherein the zinc com-ponent is recovered by sublimation during the reducing step (b).

4. The method of claim 1, wherein the gaseous plasma jet provides agitation to the melt, thereby reducing diffusive resistance, and increasing the rate of reduction.

5. The method of claim 1, wherein nitrogen is used as the plasma forming agent.

6. The method of claim 1, wherein natural gas is used as the plasma forming agent.

7. The method of claim 1, wherein a layer of coke is applied on the surface of the melt.

8. The method of claim 1, wherein the heating step (a) is conducted under an inert atmosphere.

9. The method of claim 1, wherein the heating step (a) is conducted under an oxidizing atmosphere.

10. An apparatus for continuously processing com-plex, non-ferrous metallic compositions essentially of sul-fides and oxides of zinc and metals selected from the group consisting essentially of copper, lead, antimony and mixtures thereof, comprising a melting chamber for melting said compo-sition and accumulating metal oxides thereof, a reducing-sublimating chamber connected to said melting chamber, said reducing-sublimating chamber being also connected through a gas duct to a chamber for condensating metal vapours, the lining of said reducing-sublimating chamber having at least one plas-matron built therein, said plasmatron having a nozzle which is permanently immersed in the melt for injecting thereinto a plasma jet capable of agitating and simultaneously reducing said melt, said chamber being provided with means for charging coke on the surface of said melt.

11. An apparatus as claimed in claim 10, wherein one or several plasmatrons, arranged in parallel, are set at an acute angle with respect to the surface of the melt, said plasmatrons being adjustable relative to the walls of said reducing-sublimating chamber.

12. An apparatus as claimed in claim 11, wherein there is provided a mechanism for displacing said plasmatron within the layer of the melt.