JP2011058018A - Method for recovering gold concentrate from leach residue of copper sulfide minerals - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for concentrating gold contained in a leach residue obtained by leaching copper from a gold-containing copper sulfide mineral so as to be efficiently recovered in a copper refining process where copper is recovered from a copper sulfide mineral by a wet process. <P>SOLUTION: The method is provided with: a leaching stage where a gold-containing copper sulfide mineral is leached; a floatation stage where the obtained leach residue is subjected to floatation so as to be separated into a float fraction and a sink fraction; and a desulfurizing stage where sulfur is removed from the separated float fraction, and the desulfurized product obtained in the desulfurizing stage is repeatedly subjected to each stage of the leaching, floatation and desulfurizing in order so as to be recovered as concentrated gold-containing residue. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for concentrating and recovering gold in a leaching residue obtained by leaching copper from a copper sulfide mineral containing gold in a copper smelting process in which copper is recovered from a copper sulfide mineral such as copper concentrate by a wet method. .

  Copper sulfide minerals, the raw material for copper smelting, are composed of copper-containing components such as chalcopyrite, chalcopyrite and chalcocite, iron-containing components such as pyrite, gangue components composed of silicon and calcium, and precious metal components such as gold. ing.

  In normal dry copper smelting, the above copper sulfide minerals are processed into copper concentrates that have been refined to improve the quality of copper minerals. Copper concentrates are charged into a furnace in a dry smelting process and melted, and iron and sulfur are removed. Crude copper is obtained by separation and removal as slag or gas. Crude copper is electrolytically purified as an anode in an electrolysis process to separate copper from gold and other impurities, and copper is electrodeposited on the cathode and recovered as electrolytic copper.

  Such a dry copper smelting process is highly productive, but it requires a large amount of capital investment, a lot of labor and cost for the treatment of the generated gas and slag, and problems such as difficult adjustment of operation. . Therefore, in recent years, a copper smelting method using a hydrometallurgical smelting method has been developed which can be operated with a compact facility as compared with the above-described dry smelting and can easily adjust the operation.

  For example, in Japanese Translation of PCT International Publication No. 2004-504492 (Patent Document 1), a step of pressure leaching a copper-containing substance at about 170 ° C. to about 235 ° C. to obtain a residue and a copper-containing solution, and diluting the copper-containing solution A wet copper smelting method comprising a step of diluting with a solution to form a diluted copper-containing solution and a step of solvent extraction of copper from the diluted copper-containing solution is described. However, since the gold contained in the copper-containing material is dispersed throughout the leaching residue, it is necessary to process the entire amount of the leaching residue again in order to recover the gold by this method, which requires a large cost. there were.

  Moreover, in Japanese translations of PCT publication No. 2001-515145 (patent document 2), as a wet extraction method of copper from sulfide ore, ore or concentrate is present in the presence of oxygen and an acidic solution containing halide and sulfate ions. It is described that pressure oxidation is performed, and the resulting slurry is solid-liquid separated into a filtrate and a solid residue containing a basic metal sulfate, and the solid residue is leached with an acidic sulfate solution. The leaching solution is separated from the solid residue and solvent extracted to produce a concentrated solution of metal and a metal-depleted raffinate. However, since the leaching residue obtained by this method is a state in which fine particles of iron oxide and sulfur are mixed, it is difficult to separate this and recover gold.

  As a method of separating iron oxide and sulfur contained in the copper leaching residue as described above, a method disclosed in JP-A-2002-053310 (Patent Document 3) is known. This method heats sulfur-containing materials such as, for example, sulfur concentrate obtained by flotation of zinc concentrate leaching residue from the zinc concentrate leaching process to a temperature not lower than the melting point of sulfur and lower than the boiling point. This is a method of condensing and recovering sulfur by cooling a gas containing the generated sulfur vapor at a temperature lower than the melting point of sulfur. If this method is used, sulfur can be efficiently recovered from the zinc concentrate leaching residue.

  Japanese Patent Laying-Open No. 2005-042155 (Patent Document 4) discloses a method of concentrating a noble metal from a copper ore or a residue obtained by leaching copper from a copper mineral. In this method, the leaching residue is heat-treated in a non-oxidizing atmosphere at a temperature of 550 ° C. or higher, and the obtained calcined ore is subjected to a re-leaching treatment with an acidic aqueous solution. An iron leaching product is formed. However, since the gangue components contained in copper minerals and copper concentrates often have the same distribution as precious metals, when processing copper minerals and copper concentrates with high gangue components, this method uses precious metals and veins. There was a problem that much labor was required to separate the stone components.

JP-T-2004-504492 Special table 2001-515145 gazette JP 2002-053310 A JP 2005-042155 A

  As described above, in the smelting process for recovering copper from copper sulfide minerals by a wet method, the residue from which copper was leached from copper sulfide mineral contains gold, but the gold in the leaching residue should be concentrated. However, it was extremely difficult to recover gold efficiently from the leach residue.

  In view of such conventional circumstances, the present invention, in a copper smelting process for recovering copper from a copper sulfide mineral by a wet method, the gold contained in the leaching residue leached copper from the copper sulfide mineral containing gold An object is to provide a method for concentrating and recovering efficiently.

In order to solve the above problems, the present inventors have observed a residue obtained by leaching a copper sulfide mineral such as copper concentrate with sulfuric acid. As a result, the gold contained in the mineral has a hydrophobicity in the leaching residue. It has been found that it is contained in the sulfur of similar to the above, or is accompanied by unreacted residual sulfide, and is not present in other iron oxides or gangue components. Gold is contained in the sulfur because the melting point of sulfur is as low as 100 to 115 ° C., so that the sulfur separated from the mineral by leaching becomes a molten state, and then cools and aggregates, in which case gold or leached This is probably because the remaining sulfides are included as nuclei.
Therefore, as a result of further investigations, the sulfur particles granulated from the leaching residue and the sulfide particles remaining without leaching are levitated using the difference in hydrophobicity from other iron oxides and gangue components, It was found that gold contained in the leaching residue can be concentrated by precipitating iron oxide and gangue components. Concentrated gold-containing components can be further concentrated by removing sulfur and then repeating the copper sulfide mineral leaching process, and recovering the gold-enriched residue to the desired gold quality I found out that I could do it.

  That is, the present invention is a method for obtaining a gold-containing residue containing concentrated gold from a leaching residue of a copper sulfide mineral containing gold in a copper smelting process by a wet method, wherein a copper sulfide mineral containing gold is obtained. A leaching process for leaching, a flotation process for separating the obtained leaching residue into floatation and sedimentation, and a desulfurization process for removing sulfur from the separated floatation, the desulfurization process The gold from the copper sulfide mineral leaching residue is characterized in that the desulfurized material obtained in step 1 is repeatedly subjected to the above leaching, flotation and desulfurization steps to obtain a gold-containing residue containing concentrated gold. The concentration method is provided.

  According to the present invention, in a wet copper smelting process, gold can be concentrated and efficiently separated and recovered from the leaching residue of copper sulfide mineral containing gold. Further, since gold can be concentrated and recovered, the amount of material handled in the subsequent process is reduced, handling labor can be reduced, and the scale of the production facility can be reduced, which is economical. Further, the gold-containing residue obtained by concentrating gold can be sold as an intermediate raw material containing gold, or can be recovered as a raw material for an existing smelting process.

  In the method for concentrating gold from a copper sulfide mineral leaching residue according to the present invention, the leaching residue obtained by leaching a copper sulfide mineral containing gold in the leaching process is separated into a floatation and a sedimentation by floating flotation (floating flotation process) Then, after removing sulfur from the separated float (desulfurization process), the obtained desulfurized product is repeated in the above leaching process, flotation process and desulfurization process in order, and gold concentrated to the desired grade is obtained. Let it be a gold-containing residue.

  The leaching residue of the copper sulfide mineral is a residue obtained by leaching copper from the copper sulfide mineral when the copper sulfide mineral such as copper concentrate is smelted by a conventionally known wet method. As a leaching method of the copper sulfide mineral, a conventionally known method can be used. For example, a leaching method using a mineral acid such as sulfuric acid, a method described in Patent Documents 1 and 2, or a chlorination method There is a method of leaching with an object or chlorine gas, but since the presence form of gold in the leaching residue is the same, the present invention can be applied to advancing residue by any method.

  However, when minerals that cannot be leached are contained in the copper sulfide mineral, such as pyrite in the case of leaching with chloride or chlorine gas, it is difficult to apply the method of the present invention. For example, the case where the sulfide which cannot be leached and can be contained in the leaching residue is included. In addition, since molybdenum ore is also a mineral that is not easily leached by a wet method, it is difficult to apply the method of the present invention.

  The leaching residue of copper sulfide mineral is first supplied to the flotation process. In this flotation process, the leach residue is separated into flotation and sedimentation according to a known flotation method. In the flotation process, for example, the leach residue is put into an aqueous solution, and a flotation reagent such as a foaming agent or a scavenger is added to generate bubbles such as air mechanically or chemically. By this flotation, sulfur and sulfide particles, which are likely to accompany gold, are adsorbed in bubbles and floated as floatation, while the other iron oxides and gangue components are settled.

  In the next desulfurization step, sulfur contained in the float obtained in the above flotation step is removed. As a specific method, float ore is put in a furnace filled with an inert gas such as nitrogen gas or argon gas or water vapor and heated in an inert gas to volatilize sulfur or chemically react with water vapor. This removes sulfur and separates it from gold and sulfide, which do not volatilize or react. The latter method of removing sulfur by reaction with water vapor is called a flash method, and is used as a process for recovering sulfur at a sulfur mine, for example.

  When the sulfur in the float is volatilized and removed under an inert atmosphere such as nitrogen gas or argon gas, the float is preferably heated at a temperature of 250 to 800 ° C. At a temperature lower than 250 ° C., the volatilization of sulfur becomes insufficient, so that the sulfur remains in a molten state, or the volatilized sulfur aggregates in the furnace to cause clogging. When the heating temperature exceeds 800 ° C., decomposition of the sulfide proceeds, and handling problems occur such as the leaching residue starts to consolidate as if sintered.

  Further, the heating temperature in the case where the sulfur in the float is volatilized and removed under the above inert atmosphere is more preferably in the range of 300 ° C to 400 ° C. A heating temperature of 300 ° C. or higher is particularly preferable because sulfur volatilization is promoted and the treatment proceeds in a short time. However, increasing the heating temperature beyond 400 ° C. hardly increases the volatilization rate of sulfur and only significantly increases the required energy. Since the volatilized sulfur is deposited in a temperature range lower than 250 ° C., it can be easily recovered.

  Moreover, in the said desulfurization process, in the case of the flash method in which sulfur in the float ore is chemically reacted with water vapor, it is preferable to heat to around 165 ° C. Specifically, superheated steam at about 165 ° C. is blown into the float, and sulfur and steam are reacted to decompose and remove sulfur into hydrogen sulfide gas and sulfur dioxide gas. When the generated mixed gas of hydrogen sulfide and sulfur dioxide is cooled, solid sulfur is precipitated, and therefore, sulfur can be easily recovered.

  The desulfurized product obtained in the desulfurization step is mainly composed of gold and sulfide. This desulfurized product is repeated in the above-described copper sulfide mineral leaching process, and further repeatedly in each step of the flotation process and the sulfur removal process. By repeating these steps once or a plurality of times, it is possible to decompose and remove sulfides remaining in the desulfurized product, thereby obtaining a gold-containing residue in which the gold quality is concentrated.

  That is, when the desulfurized product is supplied to a leaching process together with copper sulfide minerals such as copper concentrate to be newly treated, the sulfide is leached, so that the actual yield of copper and the gold quality can be improved. The gold contained in the desulfurized product becomes a form included in sulfur, and is concentrated in the leach residue together with the gold newly entered from the copper sulfide mineral. The leaching residue obtained in this leaching process is subsequently processed through a flotation process and a desulfurization process, thereby obtaining a desulfurized product in which gold is further concentrated. The desulfurized product obtained by repeating each step is repeated as necessary for each step after the second time, and is recovered as a gold-containing residue when it is raised to a desired gold quality.

  For the repetition to the leaching step, a desulfurized product from which oxide and gangue components are separated and sulfur is removed is optimal. When the leaching residue is repeated, iron oxide and gangue components are also repeated. Therefore, it is necessary to increase the stirring power due to the increase in slurry concentration in the leaching process and to install a large filtration facility. In addition, when flotation flotation is repeated, gold and sulfide are contained in sulfur, and the contact probability between the sulfide and the leachate is low and it is difficult to leach out. Inconveniences such as inability to proceed with the concentration of sucrose.

  Most components other than gold in the resulting gold-containing residue are copper sulfides. Therefore, by using this gold-containing residue as a conventionally known raw material for dry smelting, gold can be purified using an existing gold recovery process.

  200 g of copper concentrate having a gold grade of 2 g / t was mixed with an iron sulfate solution to adjust the slurry concentration to 200 g / l. The initial iron sulfate concentration of this slurry was 43 g / l for iron concentration and 30 g / l for sulfuric acid concentration.

  1 liter of this slurry was placed in a quartz container and charged into an autoclave with a stirrer having an internal volume of 3 liters. While stirring in the autoclave at 200 revolutions per minute, the temperature was raised to 120 ° C. and filled with oxygen to increase the pressure to 2.0 MPa, and then maintained for 1 hour while maintaining the pressure while supplying oxygen. . Thereafter, the mixture was cooled to room temperature and the pressure was lowered, and the taken-out slurry was filtered to separate into leaching residue 1 and leachate.

  The obtained leaching residue 1 was washed with pure water, 500 ml of water was added to 110 g of the collected leaching residue, and the mixture was stirred for 3 minutes to form a slurry. This slurry was charged into an agitaire type flotation tester having a cell capacity of 0.5 liter, and methyl isobutyl carbinol (MIBC) was added as a foaming agent at a rate of 200 mg per 1 kg of leaching residue. Next, PAX (trade name: potassium amyl xanthate) manufactured by Cytec Industries, Inc., USA was added as a collection agent at a rate of 100 mg per 1 kg of leaching residue.

  Thereafter, after stirring for 10 minutes, the mixture was subjected to flotation for 8 minutes while blowing air at a flow rate of 2 liters / minute while continuing stirring, and separated into 60 g of float 1 and 50 g of sediment 1. In this example, it was possible to separate the flotation and the subsidence by one flotation, but depending on the properties of the leaching residue, the flotation may be repeated. It can be determined by conducting a test.

  When the float 1 obtained by the above flotation is identified by chemical analysis, microscopic observation and X-ray diffraction, it mainly consists of unreacted sulfide mineral components and elemental sulfur, and the gold quality is 5 g / t. there were. Moreover, when the deposit 1 was identified similarly, most were iron oxide and a gangue component, and gold was hardly contained with less than 1 g / t.

  Next, 60 g of the obtained float 1 was charged into a tubular furnace using a transparent quartz tube. While flowing nitrogen gas into the furnace at a flow rate of 1 liter / min, the temperature was raised to 400 ° C., and the sulfur was volatilized and removed over 4 hours while visually observing from outside the furnace. Got. The obtained desulfurized product 1 was identified by X-ray diffraction, and it was confirmed that all the elemental sulfur was volatilized and removed. Moreover, the gold quality of the desulfurized product 1 was concentrated to 10 g / t.

  This desulfurized product 1 was repeated in the above leaching process, and after leaching with new copper concentrate under the same conditions as described above, the flotation process and the desulfurization process were subsequently performed to obtain 32 g of the desulfurized product 2. The gold quality of the desulfurized product 2 was 16 g / t. Further, this desulfurized product 2 was again subjected to the leaching process in the same manner as described above, and leaching, flotation and desulfurization were performed under the same conditions as described above to obtain 26 g of desulfurized product 3. The gold quality of the desulfurized product 3 was 24 g / t.

  In this example, for the copper concentrate, leaching residues 1 to 3, floatation 1 to 3, sedimentation 1 to 3 and desulfurized product (gold-containing residue) 1 to 3, each was dissolved in aqua regia, Analyzed by ICP, the contents of copper (Cu), iron (Fe), sulfur (S), and gold (Au) were determined and shown in Table 1 below together with their weights. In the table, the units of Cu, Fe and S are% by weight, and the unit of Au is g / t.

  As can be seen from the above results, as the number of repetitions of each step of leaching, flotation and desulfurization increases, the gold quality of the obtained desulfurized product (gold-containing residue) is 10 g / t, 16 g / t. It was confirmed that t increased to 24 g / t.

Claims (1)

  In a copper smelting process by a wet method, a method for obtaining a gold-containing residue containing concentrated gold from a leaching residue of a copper sulfide mineral containing gold, a leaching step of leaching a copper sulfide mineral containing gold, A desulfurization obtained by the desulfurization step, comprising a flotation step of flotation of the obtained leach residue and separating it into a floatation and a subsidence, and a desulfurization step of removing sulfur from the separated floatation A method for concentrating gold from a copper sulfide mineral leaching residue, wherein the product is repeated in the above steps of leaching, flotation and desulfurization to obtain a gold-containing residue containing concentrated gold.