MXPA96003325A - Procedure for the treatment of aurife sulphural minerals - Google Patents

Abstract

The ore, which contains gold and at least one of the metals silver, copper, nickel, zinc or iron, is calcined at temperatures of the order of 500 to 900 ° C, adding an oxygen-containing gas, thus forming a mixture of solid materials, which contain metal oxides, and an exhaust gas containing SO2. The exhaust gas containing SO2 is contacted with an aqueous solution, producing a solution containing sulfite. The mixture of solid materials from the calcination is cooled to temperatures between 50 and 300 ° C and mixed by stirring with the sulfite-containing solution. In this way, the metal oxides are dissolved and a solution containing sulfate is formed. In a first separation zone, the sulphate-containing solution is separated from the solids and the solids are cyed to a gold leaching device or the sulphate-containing solution is continuously treated to separate the non-ferric metals.

Description

Procedure for the treatment of auriferous sulfur minerals. DESCRIPTION OF THE INVENTION The invention relates to a process for the treatment of a granulated sulfur mineral, which contains gold and at least one of the metals silver, copper, nickel, zinc or iron, obtaining a solid mixture containing oxides metal and an exhaust gas containing S02, by calcination at temperatures of the order of 500 to 900 ° C, adding a gas containing free oxygen, Procedures of this type are already described in DE-C-4 122 895 and DE-C 4 329 417. In these cases, the calcination of the minerals in an optimized form is carried out.The exhaust gas obtained, which contains SO2, is purified and no longer comes into contact with the solid matter mixture that contains metal oxides, produced in the calcination The present invention aims to use the exhaust gas containing S02 in the treatment of the ore and thereby improve the production of metal, increasing It is the gold performance achieved. According to the present invention, this is effected in the above-mentioned process by contacting the exhaust gas containing S02 with an aqueous solution and thereby producing a solution containing sulfite, cooling the solid mixture containing oxides. from the calcination to temperatures between 50 and 300 ° C and by mixing the cooled mixture of solids containing metallic oxides with the sulphite-containing solution by stirring, thereby dissolving the metals from the solid mixture and forming a solution it contains sulfate, separating the sulphate-containing solution from the solids in a first separation zone and feeding the solids to a gold extraction device or by feeding the sulfate-containing solution to a non-ferrous metal separation device. Of course, gold leaching and non-ferrous metal separation devices can also be simultaneously powered. In the process recommended in the invention, metal oxides are dissolved from the solid matter mixture that comes from the calcination plant, forming sulphites and in part also sulphates. The solution containing sulphate, with which the cooled solid mixture containing metal oxides is mixed by stirring, can be produced, in a first variant of the process, in a washing zone, through which the gas is conducted. Exhaust containing S02. Another possibility is to conduct the exhaust gas containing S02 through a zone of agitation, in which the cooled solids mixture, containing metal oxides, is mixed and stirred with the aqueous solution. The important thing is that in all these possibilities sulphites and metal sulfates are formed, which dissolve. There is then a mixture of solid gold materials, poor in accompanying metals, which is conducted to the gold extraction device. The extraction of the gold can be carried out in a manner known per se, for example by leaching with cyanide. By previously separating the accompanying metals, the cyanide consumption in this leaching is essentially reduced. Since the mixture of solids has grains with a porous structure, due to the separation of accompanying metals previously carried out, so that this grain can be leached better, the gold yield in the operation of gold is also increased at the same time. leaching. It is also advantageous that the exhaust gas fed to the gas cleaning device has a reduced content of S02. A variant of the process consists in that, from a part of the solution containing sulphate, extracted from the first separation zone, metals are separated, the remaining solution is put in direct contact with the exhaust gas containing S02 and a second solution containing sulfate. This second solution is mixed and stirred with solid materials extracted from the first separation zone, reducing the content of accompanying metals in solid materials. The remaining solid matters are conducted to a gold extraction device. The possibilities of configuring the process are explained below with the aid of the attached drawing, in which a process development scheme is shown. For the calcination, the granulated gold ore is fed through the pipe 1. The ore, which can also be a mineral concentrate, usually has grain sizes of the order of between 0.01 and 4 mm. The calcination is carried out at temperatures between 500 and 900 ° C in the circulating fluidized bed in the calcination reactor 2 with a coupled return cyclone 3. A fluidizing gas, containing free oxygen, is blown through line 4.; this gas can be normal air, air enriched with 02 or another gas rich in 02. In reactor 2 metal sulphides are transformed into metal oxides and an exhaust gas containing S02 is produced. The solid materials and the exhaust gas reach through the channel 5 to the return cyclone 3, in which the solids are largely separated and are partly conveyed through the pipes 7 and 8 to the reactor. 2. A portion of the solid materials at high temperature passes through line 9 to a fluidized bed cooler 10, which has cooling elements 11 for indirect cooling. A fluidizing gas, for example air, is introduced through the pipe 12 and leaves heated from the refrigerator 10 through the pipe 13, which also opens into the reactor 2. A cooled mixture of solid materials is extracted from the refrigerator 10 through the pipe 15 and can be returned in part to the reactor 2 through the pipe 16 in a manner not shown in detail in the drawing. The cooled solid mixture, which contains metal oxides and which comes from the cooler 10, comes through the pipe 19 to a mixing tank 20. In this tank 20 an aqueous solution is fed through the pipe 21, which contains sulphite and sulfate, while sulfuric acid is fed through line 6. The suspension formed in the tank 20 is extracted through the pipe 22. The high temperature exhaust gas, which contains S02 and exits the return cyclone 3 through the pipe 25, is first conducted through a cooler. 26. Then, the exhaust gas comes through the pipe 27 first to a Venturi scrubber 28. With the help of the pump 29, an aqueous washing solution containing up to the scrubber 28 is fed through the pipe 30. sulfite and which is subjected to spraying in the scrubber 28. The exhaust gas and the washing liquid pass through the channel 31 to a washing column 32, which has a gas and liquid permeable layer 33 and composed of contact elements or floors. In the washing column 32, the aqueous sulfite-containing washing solution is fed through the pipe 35 and also through the pipe 36. New water is fed through the pipe 37. The exhaust gas treated in column 32 passes through line 38 to a filter 39, for example an electric filter or a sleeve filter. The exhaust gas, thus released from the powder and partly also from the S02, exits through the pipe 41. In a second washing column 42 the exhaust gas is moistened with acid solution from pipe 43 and passes to through the pipe 44 to another cleaning device not shown in the drawing. At the lower end of the wash column 32, aqueous solution containing sulfite is withdrawn and through the pipe 46 a partial stream is returned to the Venturi scrubber 28. The remaining solution reaches through the pipe 47 to a stirred tank 48 and there it is mixed by agitation with the suspension coming from the pipe 22. To the solution of the pipe 47 the solid matters separated in the electric filter 39 can be added, which is not represented in the drawing, so that this does not remain recharged and easily understandable. Soluble sulphites and sulphates are formed in the stirring tank 48 from the oxides of the accompanying metals, in particular silver, copper, nickel, zinc and / or iron. In this way, these metals are extracted at least partially the gold-based mixture of solids. It is advisable to mount a second stirring tank 50 after the stirring tank 48 in order to ensure sufficient reaction times. To this second stirring tank 50 can also be fed a part of the aqueous solution containing sulphite and reaching through the pipe 47, which is indicated in the drawing by means of pipe 52, drawn with intermittent strokes. It is also possible, although not absolutely necessary, to achieve the oxidation of the remaining sulphites, forming sulphates, in the stirring tank 50 by feeding gas containing 02, for example air fed through line 52. The suspension , extracted through the pipe 54 from the second agitation tank 50, reaches the settling tank 55, where a solid-rich gold sludge is sedimented. This sludge is extracted by pipe 56 and can be conducted to a gold leaching device not shown in the drawing. The phase poor in solids obtained in the decant tank 55 and containing metal sulphites and sulfates, is extracted by pipe 57 and distributed by pipes 21 and 58. A partial stream of this solution arrives through the pipeline 59 to an already known facility for the extraction of dissolved metals such as sulfates. Thus, in a first tank 60 silver and copper are deposited in the iron scrap and in a second tank 61 zinc is obtained by solvent extraction. The remaining solution is mixed and agitated in a third tank 64 with ground limestone coming from the pipe 63, then forming a gypsum mud. This gypsum sludge is separated from the solids phase in the decant tank 65 and can be deposited in a landfill. The remaining solution is still loaded in the column 42 through the pipe 43, together with fresh water from the pipe 45, as washing liquid. If it is desired to further dissolve the remaining companion metals, coming from the gold sludge arriving through the pipe 56, before the leaching of the gold, this sludge is conducted through the pipe 67 to another agitation tank 68, in which it charges the washing liquid from the column 42 through the pipe 69. The formed suspension then arrives through the pipe 70 to a second settling tank 71, from which the gold-bearing mud is then extracted through the pipe 72. This sludge from pipe 72 is sent to the gold leaching device, not shown in the drawing. The solid phase, obtained in the second settling tank 71, is returned to the washing column 32 again via line 36. Example: In a pilot plant corresponding to that shown in the drawing, the reactor 2 of calcination has a height of 4 meters and an internal diameter of 0.2 m. In this reactor, an amount of 20 kg / h of crude ore with a specific gravity of 2.52 kg / 1, whose fine grain ratio of less than 5 μm is 15% by weight, is loaded through line 1 through pipe 1. weight and that of coarse grains greater than 1 mm is 0.1% by weight. The main components of the mineral are the following: Fe 7.8% by weight S = 9.0% by weight Zn = 0.3% by weight Cu = 0.2% by weight C (organic) = 0.5% by weight Inert materials and quartz = 82.2 % in weigh. The mineral contains 8.5 ppm of gold and 25 ppm of silver. In the calcination reactor 2, a temperature of 680 ° C is worked and a mixture of air and Oa in a total amount of 10 Nm3 / h is fed to reactor 2 through pipes 4 and 13. The mixture of air and 02 contains 36% of the volume of 02. The calcined ore from line 19 is conducted in an amount of 19.0 kg / h and with a temperature of 200 ° C to the mixing tank (20) and has the following composition: Fe203 = 11.8% by weight S = 0.5% by weight ZnO = 0.4% by weight CuO = 0.3% by weight C (organic) = 0.1% by weight A1203 = 5.5% by weight Inert materials and quartz = 81.4% by weight. The ore also has the aforementioned gold and silver content. In the mixing tank 20, 44 kg / h of sulfuric acid diluted with 1% by weight of H2SO4 are introduced, instead of the liquids of the pipes 6 and 21, for mixing by stirring with the mineral. The liquid of the pipe 47 is replaced by 100 liters / hour of water with a content of 8 gr / liter of H2S03, renouncing the bypass pipe 51. For this, 50 liters / hour of water are conducted, also with a content of 8 g / liter of H2S03 and 250 Nl / h of 02 to a second agitation tank 50. Here also the parts of the installation bearing the reference numbers 58 to 72 are omitted. The mixture of solid materials, containing gold and silver, precipitates in pipe 56 as mud, which is washed with water to remove the solution containing sulphate adhered to said mixture. The washing water used is added to the liquid in the pipe 57. The washed mud is then dried and a solid quantity of 17 kg / h is obtained. , which contains 2.7% by weight of Fe203, 0.6% by weight of sulfur and 96.7% by weight of inert materials, and also traces of organic carbon, ZnO and CuO. The liquids obtained in the pipe 57, as well as the said washing liquid, contain together, in dissolved form as sulphate: Fe = 1260 g / h Zn = 54 g / h Cu = 36 g / h.

Claims (5)

1. Claims l. Process for the treatment of a granulated sulfur mineral, containing gold and at least one of the metals silver, copper, nickel, zinc or iron, in which, by calcination at temperatures of the order of 500 to 900 ° C and adding gas containing free oxygen, a mixture of solid materials containing metal oxides and an exhaust gas containing S02 is obtained, characterized in that the exhaust gas containing S0a is brought into contact with an aqueous solution, thus obtaining a solution containing sulfite, because the mixture of solid materials containing metal oxides from the calcination is cooled to temperatures between 50 and 300 ° C and the mixture of solid matters cooled, containing metal oxide, is mixed by stirring with the sulfite-containing solution , dissolving the metal oxides of the mixture of solid materials and forming a solution containing sulphate, and because in a first zone of s The solid solution is separated from the solids by the sulphate-containing solution and the solids are conveyed to a gold leaching device or the sulphate-containing solution is conveyed to a separation device for the non-ferrous metals. Process according to claim 1, characterized in that at least a part of the sulphate-containing solution, extracted from the first separation zone, is conducted back into the process and mixed by stirring with the cooled solid matter mixture. , which contains metallic oxides. Method according to claims 1 or 2, characterized in that at least a part of the sulfite-containing solution, extracted from the first separation zone, is brought into contact with the exhaust gas containing S02. Method according to one of claims 1 to 3, characterized in that, by stirring the sulphate-containing solution with the mixture of solids containing metal oxides, a gas containing free oxygen is intro duced. Method according to claim 1 or according to one of the following claims, characterized in that from a part of the sulfite-containing solution, extracted from the first separation zone, the solids are separated, the remaining solution is brought into direct contact with the exhaust gas containing S02 and a second sulphite-containing solution is formed, the second sulfite-containing solution is then mixed with stirring with solids separated from the first separation zone, thereby reducing the metal content of the solids and the solid materials are conducted to the gold extraction device.