AU609314B2 - Apparatus for preparing metallic lead from sulphide lead concentrates - Google Patents

Description

-LLOtNn t REPRINT OF RECEIPT 5845/2 2 1 106/8f mu S F Ref: 99377 FORM 1 7 1 1-1 11 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: pa: Name and Aadress of Applicant: Address for Service: Vsesojuzny Nauchno-Issledovatelsky Gorno-Metallurgichesky Institut Tsvetnykh Metallov (Vniitsvetmet) USSR, Ust-Kamenogorsk ulitsa Promyshlennaya, 1 UNION SOVIET SOC. REPUBLICS Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: Apparatus for Concentrates Preparing Metallic Lead from Sulphide Lead The following statement is a full description of this invention, including the best method of performing it known to me/us 5845/3 i i, TO: THE COMMISSIONER OF PATENTS

AUSTRALIA

eah:83U -Y .44 It** APPARATUS FOR PREPARING METALLIC LEAD FROM SULPHIDEI LEAD CONCENTRATES

'''SI

ot) SO 0 00 40 0 4 0'4 t) U Otto U00 OttO 0 SI* 04 o 0 4 4,44 4 4P 44 t It SI I *4 4 4'

III)

444444 a 44 4 4 II 4 44 The present invention relates to non-ferrous metallurgy, implementation of processing sulphide raw material, and, in particular, to apparatus for preparing metallic lead from sulphide lead concentrates.

Technological process in apparatus for preparing metallic 1lead from sulphide lead concentrates in bhe case of autogenous melting comprises three main stages: oxidation of lead, zinc, and iron sulphides contained in lead raw material in an oxygen atmosphere; reduction of lead oxides obtained from the melt to metal with the aid of carbon; separation of metallic lead suspension from oxide lead.

The first stage, namely, the stage of oxidation, proceeds with heat liberation and tho reduction stage with heat absorption. But since the calorific value of the lead sulphide raw material is low, the process as a whole 20 requires the use of additional heat sources (carbon fuel, electric power). Therefore, the problem is to cut down the use of additional heat sources per unit of marketable products and to decrease the output of technological gases, i a. harmful effluents, into the environment.

Known in the art is an apparatus for preparing metallic lead from lead sulphide concentrates which reoresents a shortened hollow cylinder (the diameter to length ratio rotating about the axis ("Engng.a.Mining." -2- No. 10, 1982, p. 64-65, 69, 71).

The cylinder is closed with a sealed jacket fitted with a branch pipe for gas :removal and with devices for charging lead raw material and a solid reducer, and wit devices for delivery of liquid fuel and oxygen. The apparatus operates in a cyclic mode: charging melting tappirg of the melting products.

At first lead sulphide raw material together with fluxes are charged into the apparatus and then oxygen is fed. As a result of oxidation of metal sulphides, heat is liberated due to Mhic4 the oxides and fluxes being formed 6ive rise to a melt with a high content of lead 0 0-0 oxides. After this a solid reducer (coke breeze), fuel oil, and air for burning are supilied into the apparatus. In the course of burning the fuel oil, heat is liberated which compensates heat losses through the walls of the cylinder and heat consumption for the reduction of lead oxides to metal. The degree of reduction of lead t #1 oxides is controlled by analyzing the samples of the oxide 4 melt for the lead content therein. The reduction is considered to be completed when the amount of lead in the slag is about 2% of the lead charged with the lead raw 4 4 material. After the completion of the reduction process, and tapping the depleted slag and black lead, the apparatus is prepared to a new cycle of melting the raw material and reduction of the oxid6 melt.

The design of the apparatus is disadvantageous in -3that it is impossible to obtain heat continuously due to oxidation of sulphides of metals present in the lead raw material. A considerable part of heat obtained in the course of oxidation of sulphides is consumed for heating the apparatus in the starting period. Besides, the heat due to oxidation of sulphides is liberated nonuniformly wita time: heat liberation is most intense at the initial stage when the amount of sulphides in the cylinder is maximum. However, when the amount of sulphides in the cylinder decreases as a result of oxidation, i.e. prior to the beginning of the reduction heat-consuming period of operation of the aggregate, the arrival of heat liberated due to oxidation of said sulphides decreases. Thus, the period of the most intense heat arrival due to oxidation of sulphides and the period ox an intense heat consumption for the reduction of lead oxides to metal are separated by a time interval (the cyclic operation of the ap- S paratu3). As a nesult, the oper'ation of the apparatus requires considerable additional heat sources, namely, the burning of fuel oil. This not only enhances the specific energy expenditures per unit of the marketable products but increas s the yield of melting gases calling for a thorough sanitary purification (the gases formed in burning the fuel oil are contaminated with compounds of lead).

Also kno-vn in the art is an apparatus for preparing metallic lead from lead sulphide concentrates which represents a cylindrical reservoir lined with refractory brick with a diameter to length ratio of about 1/10,the axis of the reservoir being norisontal so that the bottom of the cylinder is a hearth and the upper part is a roof Metals", V. 34, No. 6, 1982, p. 60-64).

Below the horisontal axis the reservoir is separated by a vertical partition having a hole near the hearth into two zones: a zone of charging the raw material and a zone of reduction of the melt; the cross section area of the reduction zone is about 0.65 of the cross section area of the waole reservoir. In the zone of oxiaation of the raw material there is a device in the roof of the reservoir for charging granulated le6d raw material with a diameter of the granules of about 1 cm, whereas in the reduction zone the roof of the reservoir is fitted witn bur- 0 0 .ners for burning gaseous or liquid fuel. The hearth in the oxidation and reduction zones is equipped with lances, oxygen being supplied through the lances in the oxidation zone and a mixture of carbon and air in the reduction zone. The reservoir in the oxidation zone is fitted with a hole for lead discharge and a dross hole in the face part of the cylinder in the reduction zone for removing the lead-depleted slag.

The reservoir is also equipped With hole for removing gases.

The apparatus operates in the following way. Granulated material charged into the cylindrical reservoir represents a mixture of lead sulphide raw material,fluxes, and return oxidized dusts and has a moisture content of about Therefore, upon oxidation of such granules part of liberating heat is consumed simultaneously for evaporation and heating of water vapours up to a temperature of no more than 950 0 C. This temperature is optimum since at higher temperatures an undesirable transfer of lead into the steam-gas phase increases sharply and the lining is destroyed rapidly whereas at lc wer temperatures the output of the stage of oxidative melting deceases. That is why the presence of moistuve in the granules ensures the maintenance of the temperature at tho required level. The oxide melt formed in oxidation of the s-lIphide raw material and having a hiigh content of lead oxides transfers through the partition into the reduction zone. In the reduction zone the lead oxides are reduced to metal by blowing a mixture of carbon and air through the melt. Metallic lead is precipitated on the hearth and transfers gradually into the oxidation zone through the hole in the partition whereas lead-depleted slag is removed from the reservoir througa a dross hole. To ensure a high output and to prevent a rise in the viscosity of the oxide melt, the temperature of the melt is gradually increased to 11500C, when moving from the partition to the dross hole, due to burning the fuel supplied through the burners in the roof of the reduction zone. The gases formed in the reduction zone come to the oxidation zone and then are removed from the re- 004 o >4 04 nol nl i i f. 0l servoir together with gases formed upon oxidation of sulphides. However, since the stability of the lining in melts with a high content of lead oxides is low, there is a need to decrease intentionally the calorific value of the sulphide raw material by enhancing its moisture content to therefore, in this aggregate the melt enterin6 the reduction zone has a low heat content (T 950 0 As a result, a considerable additional amount of heat is required, for instance, at the expense of burning gaseous or liquid fuel, to ensure a high temperature (115000) required for the reduction process and to compensate the consumption of heat for the reduction of lead oxides to metal and large heat losses through the walls of the reservoir in the extended reduction zone. Besides, the known apparatus has no zone of undisturbed precipitation of the oxide melt from the suspension of metallic lead Which increases the losses of lead with depleted slag. Thereforethis aggregate must be used together with an additional de- 1O vice for precipitation of lead suspension, for instance, with an electric p2ecipitator. Two structural features of this apparatus, namely, the use of a refractory protective lining and blowing of the melt with a carbonair mixture in the reduction zone, are responsible for additionaL heat consumption for evaporation of moisture and for heating the water vapdurs (which in practice is compensated by using the fuel in the reduction zone) -7- 9 (o 0 4 04 and for electric power heat consumption for precipitation of metallic zinc suspension in an additional electric precipitator.

Likewise known in the art is an apparatus for preparing metallic lead from sulphide lead concentrates (US, A, 4519836) comprising a reservoir the bottom wall of which is a hearth having a LIole for removing metallic lead, the reservoir being divided into two chambers by a vertical partition, said chambers be- 1O ing connected wita the aid of a hole in the partition near the hearth and reDresenting a melting chamber equipped wita a device for simultaneous delivery of oxygen, sulphide lead concentrate, and a solid reduced, and with a channel for removing gases having a hole for removing gases and an electrothermal chamber fitted with electrodes, a dross hole for removing slag, and a hole for removing vaoours. The partition is located in such a way that the ratio of the cross section area of the electrothermal chamber to that of the reservoir is 0.653 10" 2 108m In this apparatus all three main technological stages of processing lead sulphide raw material are combined: the stage of oxidation of sulphides contained in the raw material to their oxides, the stage of reduction of lead oxides to metallic lead, and the stage of precipitation of metallic lead suspension.

The processing of lead sulphide raw material in this 8 apparatus is accomplished in the following wvay.

A mixture of finely ground fluxes, sulphide concentrate, return oxidized dust, and ground carbon reducer (coke breeze, coal) is supplied into the melting chamber through the device for feeding the charge and oxygen. Only lead, zinc, iron, and copper sulphides contained in the lead raw material interact with oxygen whereas the particles of the reducer having a high ignition temperature (due to a great particle size) have no time to "ecome oxidized. Thus, in the bottom part of the meltin chamber the initial mixture being charged is transformed into a mixture of 0000 Fmall drops of thu oxide melt and tie particles of 0 i t the carbon reducer as a result of tau selective ino o teraction with oxygen. The particles of the rerluoer 00 0 find their way to the mirror of the oxide melt in the bottom part of the melting chamber and form a re- 004, 0 4 ducer layer with a height of from 50 to 500 mm. The 6 I drops of the oxide melt containing lead oxides pass through a carbon-containing layer. The lead oxides are reduced to metallic lead due to the heat liberated in oxidation of sulphides of the lead sulphide 00. raw material and partially at the expense of heat arrived from the melt under the carbon-containing layer. The latter fact is ensured by that the melting and electrothermal chambers aro connected with a common slag bath through the hole in the partition

I

9- ~,Io 0 0 0 0 04 4 4 .44, 4 4 44 4 4 4 4 44

SC

4 4

CC

according to the principle of commuunicating vessels.

Therefore, the part of heat liberated in the Jlectrothermal chamber due to electric power goes into the melting chamber. After paosiiig through the carbon-containing layer, the melt in which lead oxides have redaced to metallic lead combines with thle melt located under the carbon-containing layer in the coursve of which the main part of lead drops precipitates and the smallest drops pass into the electrothermal chamber together with the oxide melt. In the electrothermal chamber small drop.s of etallic lead precipitate.

Lead-depleted oxide melt ile4 removed from the apparatus through a dross Liole ftir -removing the slog. T~he meltin6 of leqd sulphide raw miateriol in the described apparatus is accomplisohed contiluoucrly and discharge or lead-depleted oxide molt and of metallic lead obtained may be either continuouo or cyclic.

Hlowever, the rwoltine, oil lead oulphide raw ,-iaterial In the apparatus is ch-arcterlzed by an increaoed consumption of electric povier which attains 400- 500 1lW'h per ton of the charge representing, a mixtare of sulphide lead concentrates, fluxes, anld return oxidized products.

Besides, the melting is accompanied with n, high yield of o.%1dized return, products and an ethanced content of fine s~54nof metallic lead 10 in the deplted slag which decreases direct extraction of lead from rcav, material into the metallic zinc being obtained and increases expenditures per unit of the marketable products.

The object of the invention is to improve the design of an apparatus for preparing metallic lead from sulphide lead concentrates by choosing such a ratio of the surface areas of the zones of raw material charge and melt reducti.n which %-ould ensure heat transfer from the elcctrotiermal chamber to the -elting chamber, said transfer enhancing the degree of direct extraction of lead and decleasing at the same time the specific consumption of electric poaer.

This object is accomplished by that iL an apparatus for preparln- metallic lead from sulphide lead conoentmates comprioing a reservoir the bottom wall of vhich 1is a hearth having a hole for retoiving metallic lead, said reservoir being divided with a vertical partition into two chambers comnunicated with one another through a hole in the partition, said hole heing located near the hearth, namely, a melting chamber equipped with a device for simultaneous CC .delivery of oxygen, oulphide load concentrate, and a solid reducer, a ohannel for removing gases with a hole for removing gases, eand an electrothermal chamber fitted witth ectrodoos, a dros hole for discharging the lage a hole for removing vapoars$ according to the invention, the partition is located In such a way that the ratio of the cross section of the electrothermal chamber to that of the reser- Yoir is within the limits deterriinecl by the inequality 0.41 81 0.65, S 1 2 whe re S 1 is the cross section area of' -the electrothermal chamber and 82is the cross section area of the meltinG chamber.

The apparatus for preparing metallic lead from lead concentrates manufcactured In accordance with the present inivention makes it Possible to enhiance the degree of direct extractiin of lead Into metallic leea by at the o~~ezse of a decreaoe in loooen of :,itallio lead bothi wi a tile oxide melt in the form of Ouiupeaoion of' small leaWdr. L olid w'ithl lead trallsfer Into a oteam-grno -hric inl the Oloctrotherm~al. chamdber', The spOocifio oonsa~ption or olecthaving tile Oat~ie capacity, the ~ea lo i4ioro ooii puct OInce a chan;e Ina tile 1 tIQ i attained by deoroci, i,4 the oso section area J 4 The iinvention wIll, beomoe :;ore fully a,parent from a devoz'iption of a apocific eiabocUlmit taerooC In con jgation with the acmnyf dvaids we '0 Fig 1ica digv~~aIc l view of tile ct ,regate fox, pprn, metallic load :rora sixlptilol lead doylont rate a iulag3 ua, ana a noLe ror removing vapours, c h a r a ct e r i z e d i n t h a t the partition is located i.n such a manner that the ratio of the cross sec- /2 12 Fig. 2 is a section taken along the line II-II in Fig. 1; Pig. 3 is the specific consumption P of the electric power as a function of SI1 S2' The apparatus for preparing metallic lead from sulphide lead concentrates shown on Figures 1 and 2 contains a reservoir 1 in the walls of which watercouled elements 2 are mounted, the reservoir being fitted vith a hole 3 for re vi metallic lead. The 1o reservoir 1 is divided by a vertical partition 4 into two ohambers 5 and 6, namely, a melting chamber 5 and electrothermal oham:ber 6 located on a common hearth 7 'bhi is the bottom wall o1 the reurvoir 1. The chambers 5 and 6 are cor=municated with one another through a hole C in the 7artition 4 near the hearth 7. The hole 3 for diohargin metallic lead is in the cho-.ber 5 in the hearth 7, The ielting chamber is fitted with a device for simrultaneous delivery of ;oxygen, Pulphide lacd concentrate t-nd a solid re- :2Q ducer, the device representin6 in thia case a chargeoxygen burner 9, and with o. channel 10 for removing 0r fases with an inner wall 11 and having on outlet hole 12. The outlet hole 12 nd tho burner 9 are located in the upper part of the chamber 5 in the wall opposite to the hearth 7. Thea electrothermal chamber 6 is equipped with Oelectrodes 13 locatod in such a manner to be moved along the vertical, a dross hole 14 for discharge of tho slag, a hole 15 for remov-

I

13 ing vapours, and a device 16 for charging a carboncontaining reducer or other solid reagents, for instance, grarnlated slag with an increased content of nonferrous metals (lead, zi.-c, copper).

Besides, the chamber 6 is fitted with an indicator 17 of the melt mirror eand an indicator 18 of the lower level of the slag melt.

The partition 4 is located in such a way that the ratio of the cross section area of the electrothermal chamber 6 to that of the reservoir 1 is within the limits determined by the inequality 0.41< 0.65,

S

1

S

2 where S is the cross section area of the electrothermal chamber 6, S 2 iu the cross section area of the melting chamber.

In the apparatus for preparinig metallic lead from sulphide lead concentrates, according to the invention, the following processes take place: 1) oxidetion and melting of sulphide components of the raw material with the formation of a dispersed oxide melt accompanied with heat liberation; 2) reduction of lead oxides from said oxide melt to metallic lead from the carbon-containing material accormpanied with heat absorption; 3) separation of the suspension of the metallic lead from the lead-depleted oxide melt.

14 As the melt passes through the carbon-containing layer, the content of lead oxides therein drops and the temperature of the melt decreases. At tho same time the drops of metallic lead are formed via the formation of either a great number of very small drops or a small number of large drops. To compensate for a decrease in the temperature of the melt in the layer, heat is arrived from the electrothermal chamber 6 due to convection and heat conductance. The melting chamber 5, carbon-containing layer, and electrothermal chamber 6 become energetically conjugated through the hole 8 as a result of which the consumpt.on of energy from the outer heat cources can be cut down. A decrease t 0 in the temperature of the melt in the course of passing thereof through the carbon-containing layer is an especially important factor': ftrstly, a lowering of the concentration of lead oxide i the melt decreases the rate of formation of me 'allic lead; secondly, a decrease in the temperature of the melt lowers even to a greater :ent the reduction rate depending exponentially on temperature. As a result, the reducing ability of the carbon-containing layer and, hence, the degree of lead extraction into metal, drop sharply. In addition, at a lowered temperature of the melt a great number of very small drops is predominantly formed which, naturally, requires prolonged sedimentation of the metallic lead suspension, i.e. a considerable surface area of the electrothermal cham- 17 15 4 040~ 41 41 C 41 o 44 41 U 44 441 4 4 4441 4 44 44 4 1~ 'Qer 6. However, in spite of the fact that in the lower part of the carbon-containing layer the nead in thermal energy is relatively lovy and only small compensation of a temperature decrease is required, the accomplishment of the proces s in aggregates where S 1 to (i+ S 2 ratio exceeds 0.65 is related to needlessly high consumption of electric power. This is due to the fact that at a ratio of S1to S2 equal to 0.65 and more a much greater melt temperature increment in the electrothermal chamber 6 is required for the attainment of the required effect in the lower part of the carbon-containing layer. Eoviever, such a temperatare rise not only increases the consumption of electric powver and heat losses through water-cooled elements 2, but enhances -the ingress of lead into a steamgas phase (this part of bad returns -Pj melting in the fc'i'm of oxidized return products) without a noticeable decrease of the suspension of metallic lead in the depleted oxide melt.

The latter fact is explained by that a rise in temperature of the oxide melt (overheating of the melt) virtaally does not influence the rate of precipitation of the suspension of metallic leaf but effects greatly the evaporation of metallic lead, including the layer of the metallic lead formed unde~r the oxide melt.

An increase of lead transfer into the return oxi- 44

I

14 1 4 4 II rial and reduction of the oxide melt.

The design of the apparatus is disadvantageous in 16 dized products is equivalent to a rise in the specific energy consumption since some part of lead passes repeatedly all three stages of processing the raw material. Thus, in the aggregate where S1/S+ S2 0.65 no economical use of electric power is attained: with increasing consumption thereof undesirable concomitant processes are intensified as compared to the main process of formation of metallic lead. Since in the melt under the carbon-containing layer and in the melt in the electrother.al charmber 6 similar phyoico-chemioal proceises takle plrce, namely, sedimentation of the suspension of metallic lead, averaea heat losses due fI I to irrevesibility of phy-ico-chemical processes must be the came for the melts in the -Qltins chamber 5 and R in the electrother,al chexbor 6.

i F F T T S( 1 2 1 2 2 where T i e Slute mperur of the ablUt tpeatUr 0 t melt at 1 the output from the carbon-containing lay- I er; T T 2 is 'he average absolute temperature of the melt in the electrothermal chamber; T 3 is the absolute temperature of the melt near the electrodes; T is the absolute teperature of the environme nt; F is the electric power; Ing metallic lead from lead sulphide concentrates which represents a cylindrical reservoir lined with refractory brick with a diameter to length ratio of about -17- 1 is the height of the melt bath (1 is identical in the electrothermal and melting chambers connected with one another according to the principle of communicating vessels).

Therefore, the S2/S ratio corresponding to the optimum use of the electric power for accomplishment of the main process, namely, the preparation of metallic lead, is

S

2 (1-T 0 /T 3 2(2) (1-To/T 2 )-(1-To/T 1 Thus, her the 82/1 value corresponds to the derived equality th.e conasumption of the electric 0 o power per ton of the lead raw material is minimum.

-n the above equation only To 296K is known; T3 can be evaluated from te literature for instance, D.A. Diomodovoky, Purnrccoc of ferrows mep, tallurgy; ioscow,Ioetallargiya, 1956, 460 The rest values (T 1

T

2 and, hence, the ratio) can be found )roceeding from the conditions of heat consumption upon reduction of lead exides in the carboncontaining layer and temperature recime of process- .4 ing the :iielt in the electrothzrmal chamber 6.

The solid line A in Fi,. 3 shows the dependence of the specific consumption of the electric power P (d.bh/t) on the value of the 82 1Sl±S2) ratio plotted by the experimental values 6f T and T2; the points a, b, c, d, ae, f, correspond to the experimental values of P obtained in the regates with diffe- LuLadoju WacfL'.Ltka. Uu.uLeu .LUU ULel CUyLuU.ULLCa.L reservoir represents a mixture of lead sulphide raw material,fluxes, and return oxidized dusts and has a moisture content 18 rent Si, the cross section area S2 of the melting chamber 5 being constant. The latter circumstance made it possible to retain constant in all the experiments the capacity of the aggregate with respect to lead sulphide raw material and thus to obtain the comparable data. The technological parameters corresponding to those experiments are given in Table 1.

Operation of the apparatus for preparing metallic lead from the sulphice lead concentrates is accomplished in the following way. Preliminary ground are dried sulphide concentrate is mixed with fluxing additives and return oxidized ;roducts, i.e. a sulphide charge is prepared which ic continuously fTd into the melting chamber 5 by a flow of coisx..erci0J oxygen together e iwith the particles of a solid carbon-containing reducer (for instance, coke, coal) through the charge-oxygen burner 9. Under the action of the *:reviously liberated heat the sulphideo of the charSe in a burning-melting zone 19 catch fire, oxidize, and malt as a result of which Pn oxide melt and SO2-concentrated gases are formed. said oxide melt in the form of small drops enter the zone of selective carbon-thermal reduction (a layer of the solid carbon-corintainin, reducer), said zone being located between the burning-melting zone 19 and melt mirror in the melting chamber 5. The S30 2 -concentrated gases arrive into the gas channel 10 viherefrom they are continuously removed through the hole 12 for renmoval of gases zone. The gases formed in the reduction zone come to the oxidation zone and then are removed from the re- 'C I ii i :I i s 19 4000n 04 Q 0 r,,)O 4 rCr, 01 0 0 n 0O 0 0* and directed for sulphur utilization accomplished by the known methods. The particle size of the solid carbon-containing reducer (from 2 to 50 nmr) is chosen in such a manner that said particles practically have no time enough to be burnt in the burning-melting zone 19 and at the same time are heated to the temperature required for selective cerbon-thermal reduction of lead oxides to metal. 2ThuL, the oxide melt and heated 7erticles of the solid carbon-containing reducer enter a zone 20 of carbon-thermal reduction from the burning melting zone 19. At temperatures of 1200- 14000C lead oxides contained in the oxide melt in the carbon-thermal reduction Lone 2j are selectively reduced to metallic load which, together -;ith the rest oxide melt (slag), run off on the mirror of earlier prepared melt in the melting chamber 5 and the COand C0 2 -containing gases formed in tho zone 20 go through a hole 21 into the gas channel 10 wherefrom they are continuously removed from the hole 12 for removing gases. Thus, the metallic lead and oxide melt formed in the carbon-thermal zone 20 enter a zone 22 for separating metallic lead and slag, continuously flowing from the melting chamber 5 into the electrothermal chamber 6 through the hole 8 in the partition 4. In the zone 22 the part of which is located in the electrothermal chamber 6 the metallic lead precipitates by gravity into a previously obtained layer of metallic lead wherefrom it is continuously 1- i -L L~ i and for heating the water vaipours (which in practice is compensated by using the fuel in th~e reduction zone) discharged 'Uhrough the hole 3 for discharging metallic lead. In the electrothermal chamber 6 the melt cornponents are partially reduced at the expense of carbon in the electrodes 13 and due to a high temperature.

As a result of carbon-thermal reduction, the part of lead remained in the slag end the part of zinc pass into fumes (vapou which are removed from the electrothermal chamber 6 throucgh the hole 15 for remov- :1 in- vapours whereas the depleted slag is dischar-ed 110 continlxou~jly or as it is accumulated from the electrothermal cham.ber 6 thiroug;h the dross hole 14 for remioving slag. The level of t.he melt mirror controlled by the indicator 17 is thle sa-me in the meltinL chamber 5 aid eloctrotherniol c, :a~ler 6 ec,:ordn t h principle of conx.unicatin- vessels.

Since tlie ai~Aount of liept obtained In the burn- A in6-melting zone 19 is insufficie.

4 t for rerform.-LnS the described technolog!icpl trocess 1, the carbontherr'Mca ra-duction zone 2u and in, the zone 22 of sepsarati~n of metallic lead and der' lo led o.idc melt (this io, related to eidothermial effects arising- in 1 carbon-therrtul reduction Find to coohi;g of the reservoir I wiith- the aid of the water-cooled alemelits 2 required because of a high coroaive nature of' the melt), additional hont is introduced as electric vo;',ier. In thiso case the use is ma-de of' the fact that the oxide melt is an electrolyte anid Joule heat liberates evein upon p,-ssin; the electric current.

21 For a better Linderstanding of the present invention specific examples of realizing thereof are given hereinbelow by way of illustrati0n. In all the examples Use was made of sulphide lead concentrate of the followin 5 composition, weight Pb 54.3, Zn 8.0, Fe 7.2, S 18.1.

Example 1 Sulphide lead concentrate was processed in apparatus for qrcnarin6 metallic lead f2 om sulphide lead concentrates. The apparatus had the following characteristics: the surfoce area S 1 of the electrotheril chamber 6 as u 1.66m x J76 the number of electrodes was equal to 2. The ra:ti of the cross section area S of the elecrotherml chniiber 6 to the sum S2 and with due re:ard for the cnuice of the cross section aroa j2 of tiUe .lting chamber ,az 0.653.

Tho results of the eporiment are -1ven in Table 1.

Example 2 The Initial data in Example 2 differ from those in Example 1 by that Sl/(S1+2) 0.650.

The results of the experiment are ,iven in Table 1.

Example 3 The initial data in Exampie 3 differ from those in Example 1 by that S 1

/(S

1

+S

2 0.635.

The results of the experiment are given in ing ard electrothermal chamber ar, connected with a common slag bath through the hole in the partition 22 Table 1.

Exa., e 4 The initial data in Example 4 differ from those in Example 1 by that S 1 /(Sl+S 2 0.432.

Thle resultz of the experiment are given in Table 1.

Example The initial data in Examrle 5 differ from t!,ose in Example 1 by that S/S 1 +3 2 U.411.

Tie reoult of tlhe oxperimeiit are oiven in Table 1.

Examnp.,e 6 The iniCtial data iIi x'll 6 .lfler from thocie 1 n Ex amle 1 b y that j 1 The rusults of thle cz:periieiit arC 6ivCn in Tablo 1 As is en from h 3 and Table 11 with a zte- 1.ative decrease in the -urfaco area ji of the eloctrotherma2 chamber 6 (0 1 /(Jl+S 2 U.65 and leuO duwl to 0.55 there is observed. a onidervble doc:Ieaoe 4n the eJ,~ctric novier conoumpti~ cnd nn increase in the direct lea-.d oxtrction, :neinly, due to a lovierixla of lo.d lessjer With the depleted olae aid, ,to a leaor extent, duo to poore2ez extrection into the fitmea :n the e le trot hermal oum ber (this part of load. :',ettrns for meltin6 rew material as R returI oxide plduct), This occura because of the fact that With 8aid decreaee of 8 IS +S and Of the electric hanced content of fine sus,;=2.on of metallic lead p4 -3 Table 1 The effect of the S 1

/(S

1 ratio on technological para..ieters of processing lead sulphide raw x.iaterial o 0.

o o o 0 00E 0 o 0 II NLead extroction, rel. 2lectric o f S /S +S into into fumes into lead- :oe r te 2 ,ta- of the delted consumpe~x pe lic elac t hie r- o;iie tion, riment lead rmal chamb- n3 lt "a h/t or 1(a) 0.653 91.1 6.5 2.3 42S 2(b) 0.650 1.5 6.3 2.1 4Ju 3(c) 0,635 p2.0 6.1 1.8 345 4(d) 0.432 32.3 0,Q 1.6 258 Q.411 31.9 6.1 1.9 4 "2 6(f) o405 91.5 6.1 2,3 465 power opecific conaiumptiuii, the ,rlt toJ;iperatr3 at the )utpput erocl tz cruii t r2~ c 2G~;eb ot t .e ccrbuo-containi,2, It,, ,r lt 0 Lafr incxveareC. Au a robaltt tha tarlvival Of :;Uta into ho, rbn-colt i i la yer onholices a 0, :ai oQ, the aezrea OLf reducti4n of load otidos to astallic; lOtd in t,4 0cyea inorveei;i. liitll increoaiL reduotlin do- ,ecr a pc' rav 1_bl forv'ation of 2.arre drops or metallic ljctd tvIk o ti a veat the en orof a nroportlonaJ. decroee in the yield of finely dispersied sae- ,,)uio n of -netllio lead. cuao down the time er fitted with elcctrodes, a dross hole for discharging the slag, a hole for removing vapours, according to the invention, the partition is located in I t 24 K: 24- of separation of the depleted oxcide melt end metallic lead in the electrothermal chamber; therefore, a relative decrease in the surface area of said cliamber does not result in an increaje of lead losi:es with the depleted melt. The effect attained by nalgarfiation of lead dropG in the carbon-cortanin S layer exceedo an opposite ef-ecot caused by a decrease in the surface area (and in the bulk of Uhe molt) of the electrothermal r~hamber, namel, a reduction of timne of suspersion precipitation. Awever, a furtler decrean e in the Lia S/(S 1 +8 2 ratio iu aom'anid with a rise in the electric -)vier Lpecl~ic coa umrn,)tion. jaid rise iii the Li, o electric poer apaoific cvnzum-)tio rnd deterior-tion of other technolo-ical -areter4 aro e Caumld by a conicAerable groth., u. heoat loeveo thirou-h water Oooled elements 2, i.e. by such di. A'1t),iOLOtn of1 the ao, intioduoed eleotric powier at ;hio ti~ lerjival of hevt to the carbon-containin- Inyer decrease, both iin ro.atIve and absolu.te vaJlueo.

The zvtuo vitht l a ratio of from 0.41 to 0*65 is suitable for poooae$ino ou2.phide lead raw lmatil -ith content Of eled from 3:-37% to 74-784t ziniz fromi to 18-25,'0, and coopev from 0 to 5-8%A When reduction of lead o-idosU to noeta2. is perforr'ed ii a layer of carbon-coiitalni n-44 aterial.. The MJeltin of said raw mrtatorial doeao no- violate qUalitatively the ectabliishea tred sixnCo the ganoralized OLation is vali. It is, also evident that the regate for Preparing metallic 'lead, from sulphide lead concenftrates; equationl is valid rnot only for an apparatus with a rectang~ilar cross section (Fig,. 2) buit for other confi- 3uration and mu~tuictl arxran~orment of the rielti .g chamber and eJ.ectrotherrtc chamber G

'DI

Claims (2)

1. An apparatus for preparing metallic lead from sul- Gor phide lead concentrates comprising a reservoir the bot- tom wall of which is a hearth fitted with a hole for dis- charging metallic lead, the reservoir being divided with a vertical partition into two chambers comriunicated with one another through a hole in the partition, said hole being located near the hearth, namely, a melting chamber fitted with a device for simultaneous delivery of oxygen, SO.O 10 sulpaide lead concentrate, and a solid reducer, and a °t channel for removing gases, and an electrothermal chamb- l er equipped with electrodes, a dross hole for discharg- ing slag, and a hole for removing vapours, c h a r a c- St e r i z e d i n t h a t the partition is located in such a manner that the ratio of the cross sec- Stion area of the electrothermal chamber to that of the reservoir is within the limits determined by the inequality I 1

2 S is the cross section area of the electrothermal chamber S 2 is the cross section area of the nmlting chamber formed which, naturally, requires prolonged sedi- mentation of the mietallic lead suspension, i.e. a considerable surf'ace area of~ the electrothermal chan-- 27 DATED this TWENTY FIRST day of JUNE 1989 Vsesojuzny Natchno-Issledovateisky Gorno-M(.tallurgichesky institut Tsvetnykh tletallov (Vniitsvetit Patent Attorneys for the Applicant SPRUSON FERGUSON 0 C