DE2542877A1 - PROCESS FOR THE EXTRACTION OF METALS FROM SULPHIDE ORES CONTAINING LEAD, SILVER AND ZINC SULFIDE - Google Patents

Description

PAYE-. N TAN Λ Al-TE Α. GRÜNECKER

DlPL-ING

H. KtNKELDEY

W. STOCKMAIR

»INC« (CAl.TEO «

K. SCHUMANN

OR RFR NAT ■ UPl. -PHYS

P. H. JAKOB

OtPL-MMG

G. BEZOLD

Dft RER WJ - ÖPL-OIFM.

MUNICH

E. K. WEIL

OR. RB * OEC ING

8 MUNICH 22

MAXlMlLtANSTRASSE 43

LINDAU

25th September 1975 P9573

CYPRUS IiSTALLUHGICAL PRCESSES CORPORATION 555 South Flower Street, Los Angeles, State of California, USA

Process for the extraction of metals from sulphide ores containing lead, silver and zinc sulphides

The invention relates to new processes for the extraction of metals from sulfide ores containing lead, silver and zinc sulfides.

Ss has already been suggested in metal recovery processes To convert metal sulfides into metal chlorides. For example Metal sulfide concentrates in aqueous sodium chloride or calcium chloride can be chlorinated with ferrous chloride and chlorine gas (see US Pat. No. 1,736,659). Ss it has also been proposed to use dry concentrates of metal sulfides containing lead, zinc and silver sulfides Use of chlorine gas to chlorinate (compare

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Ionides, "The Dry Chlorination of Complex Ores" in "Mining and Scientific Press ", Volume 112, May 27, 1916). In the presence of air, a final chlorination is carried out in a roasting stage. whereby the iron (III) chloride formed in the chlorination stage is decomposed with the formation of chlorine, which causes the chlorination of metal sulfides completed. This last one Process can be used to produce zinc chloride, but it is not an environmentally friendly one Process because in the 'roasting stage sulfur dioxide is formed which is released into the atmosphere. Also occurs when the chlorination product is treated with sodium chloride to solubilize the metal chlorides, an undesirable one Accumulation of impurities, especially zinc chloride, in the saline leach solution. This will after a certain time the ability of the solution to remove the silver and lead chlorides obtained from the chlorinated ore product to solubilize adversely affects.

The invention is an improved method for Extraction of metals from a sulphide ore concentrate containing lead, silver and zinc sulphides, characterized in that is that one

(a) The concentrate is chlorinated to convert the metal sulfides into metal chlorides and the sulphide sulfur in elemental sulfur to convert

(b) leaches the residue from step (a) with aqueous sodium chloride to remove the lead and silver chlorides contained therein to dissolve and remove these chlorides from the insoluble solids,

(c) the sodium chloride leach solution cools to practically the precipitate all of the lead chloride contained therein, and then separating the precipitated lead chloride from the leaching solution,

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(d) recovering silver from the lead chloride-depleted leaching solution obtained in step (c),

(e) some of the solution formed in step (d) is removed and the remainder of the solution is added to the leach solution of step (b) introduces,

(f) practically all of the zinc and the remaining impurities from the portion of the solution separated in step (e) removed,

(g) the removed part of the solution is electrolyzed to form chlorine gas,

(h) the resulting portion of the solution in stage (b) and leads back

(i) the chlorine gas formed in step (g) is returned to the dry chlorination step (a).

When using the method according to the invention, lead, Sulfide ore concentrates containing silver and zinc sulfides treated especially to extract silver and lead from it. The extraction of metals from their chlorides, which in of the chlorination stage, it is carried out in such a way that in the sodium chloride leach solution used to solubilize the isietal chlorides formed in the chlorination step Accumulation of contaminants including zinc chloride is prevented. As an alternative to wet chlorination of the sulfides, dry chlorination can also be carried out using dry chlorine gas with heating to convert the sulfides to chlorides and the chlorides of arsenic and Antimony to volatilize when these metals are present. It has been found that dry chlorination is particularly beneficial is effective with sulfides of the tetrahedron-tennantite series either alone or in combination with another mineral, such as

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Galena.

After chlorination of the sulfides by any suitable method, the metal chlorides are obtained from the resultant Separated solution and the metals of interest lead and silver are separated from the separated aqueous Chlorides obtained. The lead chloride is crystallized by cooling and the lead can be obtained from the lead chloride by electrolysis of the molten salt, which in doing so chlorine formed is introduced into the chlorination stage. The silver can be depleted of lead chloride by cementation Solution can be obtained. The resulting solution depleted in lead and silver, from which a part has been separated, is returned to the sodium chloride leach solution. Of the separated part of the metal-depleted solution is preferred after removal of the lead and silver by iron cementation neutralized with sodium carbonate to remove zinc and other metal contaminants in the form of carbonates. During the electrolysis of the resulting solution, chlorine is produced, which is fed into the ore-chlorination stage. A Part of the dilute sodium chloride electrolyte formed is concentrated and introduced into the sodium chloride leaching solution, to prevent the accumulation of zinc and other contaminants when the process is carried out continuously will. The sodium hydroxide from the electrolysis is preferably converted into a carbonate and the sodium carbonate obtained in the process is used in the neutralization stage.

By separating off a portion of the sodium chloride leaching solution after the lead chloride has been removed and then recycling it it is in the sodium chloride leach solution after removing zinc and other metal contaminants from it possible the zinc chloride at practically the same rate from the saline leachate with which it is added through the ore. This can lead to an enrichment in the saline leach solution, the

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otherwise it would prevent the solubilization of lead chloride. In addition, the chlorine remains in the system, so that is practical no chlorine leaves the system as chloride in contaminants or otherwise. All of the chlorine that's removed from it is removed in the form of chlorine gas in the electrolysis and introduced into the chlorination stage with practically no loss of chlorine. The inventive method is an environmentally friendly, d. H. the environment practically non-polluting ^ process, which does not release chlorine or lead vapors or compounds into the atmosphere. In contrast to the pyrometallurgical The process converts practically all of the sulphide sulfur into elemental sulfur instead of sulfur dioxide.

The method which is the subject of the invention is as follows with reference to the accompanying schematic drawings on the basis of preferred embodiments explained. Show:

1 is a flow diagram showing the various stages of an exemplary embodiment of the invention Procedure shows; and

2 is a flow diagram showing the chlorination of a concentrate containing lead, silver, zinc and antimony in represents an oven.

The concentrate used was a galena (galena) / tetrahedral (antimony ore) concentrate the following analysis:

Silver 0.30 - 0.35 %

Lead 68-70%

Antimony 0.80 -1.4%

Sulfur (total) 14--17% Zinc 4-6 ° / o

Iron 2-4 %.

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Of course, other ores such as lead, silver and contain zinc sulfides, treated according to the invention. The reactions occurring in the chlorination stage are as follows:

MS + GIp - * MCl ₂ ; (M = Pb, Zn, Cu, Fe or Ag and the same)

S ₂ + Cl ₂ → S ₂ Cl ₂

MS + S ₂ CL ₂ - ■> MCl ₂ + 3/2 S ₂

Sb ₂ S ₂ + 5 Cl ₂ -> 2 SbCl ₅ + 3/2 S ₂

Before the chlorination, the ore concentrate was ground to such a particle size that it was cleared through a sieve -65 mesh, and the milled concentrate was dried.

Effective utilization of the chlorine gas has been achieved by placing the powdered concentrate in a countercurrent system brought into contact with the chlorine. As shown in FIG. 2, the finely divided concentrate enters the upper end of a rotary kiln in and on the bottom, the concentrate discharge end of the pipe, dry chlorine gas is introduced so that the highest concentration of chlorine gas is almost completely with the chlorinated concentrate comes into contact. An inert purge gas, such as. B. nitrogen, is put in the furnace along with the chlorine initiated to remove sulfur chlorides, which will be explained in more detail below.

The length of the furnace is divided into two zones. The one at the end of the discharge adjacent zone (zone 2) was operated at a temperature of about 115 ° C and the upper end of the tube (zone 1) was operated at a temperature of 80 to T15 ° C. The chlorination occurred mainly in zone 1 and in the In Zone 2, sulfur chloride gases were evolved. The gases leaving the furnace, the volatilized antimony pentachloride

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_ 7 -

(SbGl ₁ -) were treated in a scrubber (gas scrubber) to remove therefrom the antimony compounds obtained therefrom. In a similar way, arsenic can be removed if the concentrate contains arsenic sulfide. A certain amount of chlorine gas per unit weight of concentrate was metered into the furnace in order to convert practically all of the lead and silver contents in the concentrate into their respective chlorides as part of a continuous process. It has been found that a furnace temperature of 50 to 150 ^O C is satisfactory, with a preferred range is from 80 to 115 ° C.

Excessive stickiness of the concentrate in the furnace can be avoided if the temperature inside the furnace is kept below the melting point of sulfur, which is about 119 ° C. Since the reaction between lead sulfide (PbS) and chlorine is exothermic, a certain amount of cooling may be necessary in zone 1. However, an inert material such as sand or recycled product can also be added to the concentrate as a diluent. In zone 2, the heat can be used to increase the vapor pressures of sulfur chlorides so that they can be purged out by the purge gas such as nitrogen. A minimum of sulfur chlorides is desired in the chlorination product in order to avoid that they are hydrolyzed in the subsequent sodium chloride leaching. Such a hydrolysis reaction for S ₂ Cl ₂ can be represented by the following equation: S ₂ Cl ₂ + 2H ₂ O - * 2HCl + H ₅ S + SO ₂ (or PoIy t hi ο n-

acids).

The amount of chlorine gas required depends on the composition of the concentrate being treated. In the case of galena / tetrahedral concentrates, most of the chlorine is used for chlorinating the galena (PbS). These concentrates generally contain around 70 % lead and the theoretical chlorine requirement for the conversion is PbS + Cl ₂ -> PbCl ₂ + 3 per ton (metric

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Ton) of the concentrate is 215 kg. The remaining 4-5 to 65 kg of chlorine (the total amount of chlorine added is up to 280 kg of chlorine per ton of concentrate) is used for chlorination of the tetrahedral and some of the existing sulphides of other metals, such as zinc, bison, copper and others. The following Example illustrates the dry chlorination of a lead sulfide concentrate and the subsequent solubilization the resulting metal chlorides with sodium chloride.

example

Chlorination conditions: Rotary kiln with three sections Apparatus: Clp addition 260-270 kg / t PbS
Brz Reaction, in zone 1: Inert gas: Nitrogen. _NO : C1 _O
= 1: 1 (volume ver
ratio) temperature 80 ⁰ C Time 2 hours Inert gas: nitrogen Reaction in zone 2: temperature 110 to 115 ⁰ C Time 1.5 hours Pulp density 50 g chlorinated
Product per liter
Leach solution Leaching conditions: Aualauglösung 290 g / l NaCl,
pH 1.5 temperature 95 ° C Time 1.5 to 3 hours

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Analysis in %

PbS concentrate 100 g

chlorinated

product

121 p

Leached residue 18.6 g

Ag 0.34 0.28 0.012 Pb 70 58 0.12 Sb 1.2 0.41 0.098 Zn 4.5 3.7 16 Fe 2.7 2.3 7.9 Cu 0.94 0.80 0.18 Cl <0.1 23

% Sb volatilized during chlorination = 59

% extracted during NaCl leaching - Ag = 99.3

Pb = 99.9

Sb = 96

Zn = 33

Fe = 47

Cu = 97

The above results show that more than 99% of the in The lead and silver present in the concentrate are converted into the chloride and extracted during the sodium chloride leaching process became. In addition, a considerable amount of antimony was recovered. In the dry chlorination stage was practically the all sulphide sulfur is converted into elemental sulfur.

When using dry chlorination at a low temperature (80 to 115 ⁰ C) with controlled addition of chlorine (260 to 280 kg of chlorine per ton of concentrate) and subsequent sodium chloride leaching at 90 to 95 ° C for a period of 1 hour, 99 % of the Silver, 99.9% of lead, 33 %

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of zinc, 47 ^j / o of iron, 97% of copper and 96% of antimony extracted. During the chlorination, the antimony evaporated, probably in the form of SbCl ₁ -, and it was recovered from the exhaust gases. Arsenic, if present, can also be obtained in this way. Virtually all of the sulphide sulfur in the metal sulphides has been converted to elemental sulfur, as opposed to the pyrometallurgical processes in which the sulfur is discharged in the form of polluting sulfur dioxide.

With reference to the flow sheet shown in FIG. 1, the leaching process described in the above example can be carried out as follows: Regardless of whether dry or wet chlorination is used, after the in the flow diagram shown in Fig. 1 beyond the chlorination stage to be worked. The chlorination product is leached in the sodium chloride leaching with a sodium chloride solution, to solubilize the lead and silver chlorides, as well as other metal chlorides that act as impurities. Once started, the saline leaching solution is recirculated by sodium chloride as part of a continuous Procedure as shown, added. The leach solution for the tetrahedral / galena concentrate contains during of operation per liter usually 260 to 280 g of sodium chloride, about 40 g of lead, about 0.15 g of silver, about 15 up to 30 g zinc, about 15 to 30 g iron (II) and smaller amounts on copper, antimony, calcium, magnesium, manganese, aluminum and the like. The saline leaching stage becomes independent of the treated concentrate is preferably carried out at a temperature of about 80 to about 100 ° C. The leach slurry is filtered hot and the residue is discarded or, if desired, for the recovery of elemental Sulfur worked up.

The extraction of lead then follows the one indicated below Way: The solubilized lead chloride is through

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Cooling from a temperature of 80 to 10O ⁰ C to about 15 to 20 ° C crystallized from the sodium chloride leaching solution. The resulting crystalline lead chloride is separated from the solution, for example by centrifugation, dried and electrolyzed in a molten salt cell to form the desired product lead and chlorine gas, which is returned to the chlorination stage.

Then, by cementation from the lead chloride-depleted sodium chloride leaching solution using metallic Iron or lead to produce an unclean silver sponge that contains some copper, lead, iron and other traces of impurities contains the silver to be extracted. Refining this sponge can produce pure silver. The lead and silver-depleted leaching solution formed in the process, a part of which has been separated, is as indicated in the sodium chloride leaching stage returned.

About 5 to about 15% of the metal-depleted leach solution are treated to remove impurities, especially zinc chloride, therefrom and the resulting impurities depleted solution is returned to the saline leaching stage. This makes it possible to reduce the concentration of the Zinc chloride and the other impurities in the leach solution to control (to control), since the zinc chloride the solubility of the lead chloride in sodium chloride solutions clearly reduced. Accordingly, it will be used to dissolve large Amounts of lead chloride include the zinc chloride and the other impurities from a portion of the metal-depleted leach solution removed at practically the same speed, v / how they are introduced into the chlorination stage.

By treating part of the metal-depleted solution, it is possible to remove the impurities in a form other than in the form of chlorides, otherwise there would be a loss of chlorine in the system. The chlorine is obtained as a gas

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and introduced into the chlorination stage, whereby a loss of chlorine from the system is avoided.

As shown in Fig. 1, the lead remaining in the portion of the metal-depleted solution is cemented with it metallic iron is removed and the resulting sponge lead is recycled to the silver cementation stage. Bs can also possibly cemented silver with im The concentration of dissolved lead in this part of the solution increases from about 15 about 0.2 g per liter.

This separated part of the solution is then kept at pH from about 8.5 and at a temperature from about 50 to about 80 C neutralized with sodium carbonate to remove zinc, iron and other metal impurities in an easily filterable Form, for example in the form of carbonates, to precipitate. Sodium carbonate is used for this because it is combined with zinc chloride reacts to form sodium chloride, which is then electrolyzed, so that in the removal of zinc and other contaminants, no chlorine is lost from the system goes.

The separated part of the solution (the tapping solution) is electrolyzed after removal of the solids to form Chlorine gas, sodium hydroxide and a dilute sodium chloride solution. The previous removal of zinc and other impurities from the solution greatly facilitates electrolysis, since electrolysis is almost physically impossible when zinc and the other impurities are present in the electrolyte are. The sodium hydroxide is converted into a carbonate with the formation of sodium carbonate, which is then recycled to the neutralization stage is returned. The chlorine gas is introduced into the chlorination stage and the impurities depleted Sodium chloride solution is concentrated and returned to the leaching stage to reduce the accumulation of zinc in the

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To prevent leaching.

The method in which the principle of the present invention is applied, can of course be carried out continuously or discontinuously (batchwise). On the base the results obtained using dry chlorination are the material balance for a typical commercial one Lead sulfide concentrate (galena / tetrahedral) as follows:

Roughly calculated material balance for galena / tetrahedron

kg / t concentrate

Ag Pb Sb Zn Fe Cu S raw materials

PbS concentrates 5.00 618 10.6 39.7 23.7 8.3 140

Iron powder 16

Products ³ > ^{00 618 10} > ^{6 39} ' ^{7 39} ' ^{7 8} > ^{3 140}

Lead 611.4

Ag sponge 2.96 2.2 4.0 2.2 7.9 Sb chloride 6.2 ~ 4

Leach residue 0.04 3.5 0.4 26.5 12.8 0.4 ~ 136

Impurities η

(Carbonates) 0.9 13.2 24.7

3.00 618 10.6 39.7 39.7 8.3 140 All of the chlorine gas added was used internally.

The table above shows that theoretically all lead and silver would be without loss of chlorine from the system can be won. After the start, practically no chloride has to be added to a continuously carried out process in which losses occur, for example from

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the mechanical operations, such as B. filtering, concentrating and the like result.

Although the invention has been described above with reference to the treatment of a tetrahedron / galena concentrate, the lead, Contains silver and zinc, and using a dry Chlorination process explained in more detail, but it is in no way to the treatment of this ore or to the application restricted to dry chlorination. For example, dry or wet chlorination can generally be applied to ores containing lead, zinc and silver. Regardless of the chlorination process used, one can use the work in the flow diagram shown in Fig. 1 beyond the chlorination stage. Also, metals can be made from their chlorides obtained by the wet chlorination of their sulphides and the results obtained are comparable to those achieved in the example described above.

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Claims (22)

Claims 1. Process for the extraction of metals from a lead, silver and sulfide ore concentrate containing zinc sulfides, characterized in that (a) The concentrate is chlorinated to convert the metal sulfides into metal chlorides and the sulphide sulfur in elementary To convert sulfur, (b) the residue of step (a) leached with aqueous sodium chloride to remove the lead and contained therein To dissolve silver chlorides and remove these chlorides from the insoluble solids, (c) cools the sodium chloride leaching solution to practically _{precipitate the lead chloride contained therein}} and then separating the precipitated lead chloride from the leaching solution, (d) recovering the silver from the lead chloride-depleted leaching solution obtained in step (c), (e) separating part of the solution obtained in step (d) and the remainder of the solution in the leaching solution returns to stage (b), (f) practically all of the zinc and other impurities from the portion of the separated in step (e) Solution removed, (g) The separated part of the solution is electrolyzed under Formation of chlorine gas, (H) the part of the solution obtained in this way is returned to step (b) and Γ. 09818/0684 (i) the chlorine gas formed in step (g) is returned to the dry chlorination step (a). 2. The method according to claim 1, characterized in that it is carried out continuously. 3. The method according to claim 1 or 2, characterized in that that the lead and silver remaining in the part of the solution separated off in step (e) are removed by iron cementation removed before the zinc is removed in step (f). 4 ·. Method according to one of the preceding claims, characterized in that ■ characterized that the zinc: from dan ai ^ ttsrrabsn part of the solution in the stage (f) is removed by neutralization with Sodium carbonate with the formation of sodium chloride and zinc carbonate. 5. The method according to claim 4, characterized in that the Sodium hydroxide formed in the electrolysis of the sodium chloride in step (g) is converted into a carbonate with formation of sodium carbonate, which is used to carry out the neutralization. 6. The method according to any one of the preceding claims, characterized in that the part separated off in step (h) the solution is concentrated before it is returned to step (b). 7. The method according to any one of the preceding claims, characterized in that the concentrate in step (a) under Application of dry chlorination is chlorinated with dry chlorine gas. 8. The method according to claim 7), characterized in that the dry chlorination at a temperature below the 609818/0684 Melting point of elemental sulfur is carried out. 9. The method according to claim 7, characterized in that the dry chlorination at a temperature of 50 to 150 C. is carried out. 10. The method according to any one of the preceding claims, characterized in that the sodium chloride leach solution 250
contains up to 300 g sodium chloride per liter. 11. The method according to any one of the preceding claims, characterized in that step (b) is carried out at a temperature of 80 to 10O ⁰ C. 12. The method according to any one of the preceding claims, characterized in that the sodium chloride leaching solution
from stage (c) ^{cools to about 20 0} C to lead chloride
to fail. 13. The method according to any one of the preceding claims, characterized in that the silver in step (d) by Metallic iron cementation wins. 14-, method according to any one of the preceding claims, characterized characterized in that a galena / tetrahedral ore is used as the concentrate. 15 «Process for the extraction of metals from a galena / tetrahedrite bronze concentrate, the lead, silver, antimony and zinc sulfides, characterized in that one (a) the powdered concentrate with chlorine gas at a
Temperature from 50 to 150 ⁰ C dry chlorinated to the
To convert sulphides into chlorides to the formed
To volatilize antimony chloride and to convert the sulphide sulfur into elemental sulfur, 609818/0684 (b) the residue from step (a) at a temperature from 80 to 100 ° C with an aqueous solution containing 25O to 300 g of sodium chloride per liter to to dissolve the lead chloride and silver chloride, and to extract these chlorides from the remaining solids, (c) cool the sodium chloride leach solution from step (b) to about 20 ° G to virtually all of the lead chloride to precipitate and to separate the precipitated lead chloride, (d) the lead chloride obtained in step (c) melts and the molten salt electrolyzes to form of chlorine gas and lead, (e) introduces the chlorine gas from stage (d) into stage (a), (f) from the lead chloride-depleted leaching solution remaining in step (c) by cementation with metallic iron wins the silver, (g) 5 to 15% by weight of the leach solution depleted in silver and lead from step (f) and the remainder of the metal-depleted leach solution in the leach solution returns to stage (b), (h) the lead and silver remaining in the separated part of the metal-depleted solution by biscementation removed, (i) from the separated part of the metal-depleted solution using sodium carbonate and zinc other impurities precipitate, (j) the sodium chloride in the separated portion of the 609818/0684 - -19 - Metal-depleted solution electrolyzes to form of chlorine gas, (k) returning the chlorine gas from step (j) to step (a) , (1) the sodium hydroxide formed in step (j) into the Carbonate is transferred with the formation of sodium carbonate and the sodium carbonate is returned to stage (i), and (m) the sodium chloride solution from step (j) into step (b) returns. 16. The method according to claim 15, characterized in that a concentrate containing arsenic sulfide is used and that the arsenic in stage (a ") evaporates. 17 · Process for the extraction of metals from an ore containing lead, silver and zinc sulphides, characterized in that, that the sulfide ore is chlorinated with the formation of metal chlorides and with the liberation of elemental Sulfur, to remove the lead and silver chlorides, which leaches the chlorides with sodium chloride, by cooling the Leaching solution separates the lead chloride from the silver chloride by cementing the lead chloride-depleted solution Silver wins, the concentration of zinc and other impurities in part of the lead and silver depleted leach solution and the part treated in this way the leaching solution is returned to the leaching stage. 18. Process for the extraction of metals from a sulphide ore which contains at least the sulphides of lead, silver and zinc, characterized in that the sulfides are converted into chlorides by chlorination, the chlorides in one Makes sodium chloride solution soluble by crystallization <"03818/0684 the lead chloride is removed from the leaching solution for recovery of lead, by cementation from the leach solution that Silver wins by removing the zinc in the form of zinc carbonate from part of the solution obtained, the sodium chloride containing zinc-depleted solution electrolyzed to form chlorine, the chlorination stage being carried out using dry chlorine gas, around the metal sulfides in metal chlorides and the sulfide sulfur to convert into elemental sulfur. 19. The method according to claim 18, characterized in that the leaching solution is returned to the sodium chloride leaching stage after the lead and silver have been removed therefrom. 20. The method according to claim 19, characterized in that the zinc is removed from part of the lead and silver depleted solution and the part of the solution obtained in this way added to the leach solution in the leach stage. 21. The method according to claim 20, characterized in that ' the separated part of the solution is electrolyzed after removal of the zinc from it with the formation of chlorine gas, which is introduced into the dry chlorination stage. 22. The method according to claim 21, characterized in that Sodium carbonate is added to precipitate the zinc as zinc carbonate, the sodium hydroxide formed in the electrolysis converted into the carbonate with formation of sodium carbonate and the sodium carbonate formed in the Recirculates zinc carbonate precipitation stage. 609818/0684