A method for recovering gold, silver and copper from sulfur concentrate roasted sand washing wastewater

Abstract

The present invention relates to a method for recovering gold, silver and copper from sulfur concentrate roasted sand washing waste liquid, comprising the following steps: (1) detecting the content of gold, silver and copper in the sulfur concentrate roasted sand washing waste liquid; (2) adding lime milk solution to enrich and precipitate the gold, silver and copper in the washing waste liquid, and then performing solid-liquid separation, with a pH of 7-8; (3) a gold and silver recovery process; slurrying the filter residue obtained in step (2), adding lime milk solution to react, with a pH of 10-11, and cyaniding the reacted pulp to leach activated carbon to adsorb gold and silver; wherein the stirring speed is 300-500 revolutions per minute; (4) a copper recovery process, solid-liquid separation of the pulp treated in step (3), the filter residue grinding concentration is 50-60%, and solid-liquid separation is performed after the addition of dilute sulfuric acid to react completely; iron powder is added to the filtrate to react, and the pulp is concentrated and filtered again, and the filter residue is a copper concentrate. The present invention can recover insoluble solid fine particles of gold and silver in the sulfur concentrate roasted sand washing waste liquid.

Description

Technical Field

[0001] The invention relates to a method for recovering gold, silver and copper from sulfur concentrate roasted sand washing wastewater, belonging to the field of mineral processing, and particularly to the technical field of chemical mineral processing of gold-silver-containing pyrite in gold mineral processing. Background Art

[0002] Gold exists in the nature in the form of single substance and is produced in fine particles. Large pieces of natural gold are rare, and a considerable part of gold is attached to the ore and associated with sulfides. The gold recovery rate of such ores extracted by traditional direct cyanidation is very low. For such ores, the most effective way is to use roasting pretreatment before cyanidation to convert metal sulfides into easily soluble metal oxides or metal sulfates, thereby eliminating the sulfide's coating on gold, reducing the consumption of cyanide in the cyanidation operation, and improving the leaching rate. At present, most gold enterprises adopt the method of boiling furnace oxidation roasting-water washing pretreatment-gold and silver leaching. The water washing pretreatment is mainly to remove sulfur and trace copper in roasted sand, eliminate the influence of these elements on subsequent cyanidation operations and improve the quality of iron concentrate. However, in actual production, due to the characteristics of roasting, iron, a small amount of fine particles of gold and silver will be lost during the water washing pretreatment process. Because the content of these precious metals in the water washing wastewater is low, their recycling value is often ignored. Basically, after purification meets the standards, the water is recycled or discharged for production, and the sludge is discarded for tailing treatment. For liquids containing high content of useful metals such as gold, silver, and copper, the main recovery method (1) electrodialysis operation has two types: one is a common electrodialysis process composed of alternating cation membranes and anions, which is mainly used to simply separate pollutant ions from wastewater, or to separate pollutant ions and non-electrolyte pollutants in wastewater, and then treat them by other methods; the other is a special electrodialysis separation process composed of composite membranes and cation membranes, which uses the polarization reaction in the composite membrane and the electrode reaction in the electrode chamber to produce H + Ions and OH - ions, and produce acids and alkalis from wastewater. 2+ 、Zn 2+ Cr (Ⅳ)、 Ni 2+Wastewater containing metal ions such as gold and silver is suitable for treatment by electrodialysis. Among them, the most widely used is to recover nickel from nickel plating wastewater. At present, electrodialysis technology has not been applied to the treatment of gold-containing precious liquid, but studies have shown that three-stage electrodialysis can obtain a gold removal rate of 99% and a gold grade index of <0.02mg / L in the desalinated liquid, and the cyanide concentration meets the discharge standard. Electrodialysis technology is difficult to treat wastewater containing less metals such as gold, silver, and copper. It requires multiple stages of electrodialysis, which is a complicated process. Gold and copper will migrate simultaneously. In the later stage, gold and copper separation is required. At the same time, electrodialysis targets ions. For insoluble solid fine particles in the wastewater, it is difficult to achieve the effect of enrichment, separation and recovery. (2) Use sulfiding agents to convert heavy metal ions in wastewater into insoluble metal sulfide precipitates, and then add surfactants to change the hydrophobicity of the precipitate surface. The hydrophobic precipitate adheres to the frother and floats, thereby removing or recovering heavy metal ions in the water. The sulfidation method has expensive reagents, large residual amounts, and produces harmful gases such as hydrogen sulfide and sulfur dioxide during the reaction process, which poses an environmental safety hazard. At the same time, due to the low content of heavy metal ions, the generated metal sulfide precipitation is small and the crystal particles are small, that is, the concentration is low, the flotation foaming effect is poor, and the recovery rate is low; the general flotation requirement is 25-45% for roughing and 10-25% for fine. (3) Ion exchange method: With the help of the exchange of ions in the solid ion exchanger with ions in the dilute solution, the purpose of extracting or removing certain ions in the solution is achieved. It is a unit operation belonging to the mass transfer separation process. This method has high equipment investment and expensive processing costs. The resin used needs to be frequently regenerated. There are also problems such as resin poisoning and aging. At the same time, it is also aimed at ions. For solid fine particles that are difficult to dissolve in the waste liquid, it is difficult to achieve the effect of enrichment, separation and recovery.

[0003] (4) Adsorption method: a simple and easy wastewater treatment technology, generally suitable for water treatment systems with large treatment volume and low concentration. This method uses a solid material with a high specific surface area and insoluble as an adsorbent, and fixes the pollutants in the water on its own surface through mechanisms such as physical adsorption, chemical adsorption or ion exchange, thereby achieving the purpose of purifying water. However, there are certain difficulties in the regeneration, recovery and reuse of the adsorbent, and the competitive effect of coexisting ions must also be considered; (5) Metal replacement reduction method: a chemical reaction in which a single substance reacts with a compound to generate another single substance and compound. For fine particles of gold and silver, no replacement is required, but the content is low and the particles are fine, making direct recovery difficult; for copper ions, metal iron is used to reduce and replace copper ions to generate sponge copper, but the copper content in this type of water washing wastewater is low, the copper ion activity is insufficient, and the reduction replacement rate is low. (6) Extraction method: Based on the different solubility of organic solvents for different metal ions, the metals in the solution can be enriched and separated. The LLX series of extractants are used for non-ferrous metal copper. However, this method is costly for treating wastewater with low copper content and is prone to secondary pollution of organic matter. In addition, the extraction method is also targeted at ions, and cannot achieve the purpose of recovery for solid fine particles of gold and silver that are difficult to dissolve in the wastewater. Summary of the invention

[0004] The present invention provides a method for recovering gold, silver and copper from the waste water washing liquid of sulphur concentrate roasting sand, which mainly contains gold, silver and copper. The method can recover the insoluble solid fine particles of gold and silver in the waste water.

[0005] The specific technical scheme is: a method for recovering gold, silver and copper from sulfur concentrate roasted sand washing wastewater, comprising the following steps:

[0006] (1) Detection of gold, silver and copper content in sulfur concentrate roasting sand washing wastewater. The sulfur concentrate roasting sand washing wastewater mainly contains gold, silver, copper and iron ions. The sulfur concentrate roasting sand washing wastewater is hereinafter referred to as wastewater;

[0007] (2) Enriching and precipitating gold, silver and copper in the wastewater from water washing; placing the wastewater in a stirring barrel and adding a lime milk solution to stir, controlling the pH value at 7-8 after the reaction is complete, and then performing solid-liquid separation;

[0008] (3) Process for recovering gold and silver: the filter residue obtained in step (2) is slurried to obtain a slurry with a concentration of 30-40%, and then a lime milk solution is added and stirred, and the pH value is controlled at 10-11. After the reaction, sodium cyanide is added to the slurry for leaching, and then activated carbon is added to adsorb gold and silver. When the lime milk solution is added and stirred, the stirring speed needs to be controlled at 300-500 revolutions per minute to prevent the copper adsorbed and sandwiched by calcium sulfate from reacting with cyanide, and the gold and silver carbon is sent to desorption and purification to recover gold and silver;

[0009] (4) Copper recovery process, the ore pulp treated in step (3) is subjected to solid-liquid separation, and the filter residue is subjected to grinding treatment; the grinding concentration is controlled at 50-60%, dilute sulfuric acid is added for acid leaching, and the ore pulp after acid leaching is subjected to solid-liquid separation; the filtrate is added with iron powder for reaction, and the ore pulp after the reaction is concentrated and filtered again, and the filter residue is the copper concentrate.

[0010] Furthermore, the mass fraction of the lime milk solution added in step (2) is 10-15%, the pH value is controlled at 7-8, the amount of lime milk solution added is measured by a pH meter, and the stirring time is 5-8 minutes to allow the chemical reaction in the liquid to be sufficient.

[0011] Furthermore, in step (3), a lime milk solution having a mass fraction of 10-15% is added and stirred, the pH value is controlled at 10-11, the amount of addition is determined by a pH meter, and the alkali leaching is performed for more than 30 minutes.

[0012] Furthermore, in step (4), the concentrated filtered water from the slurry from which gold and silver are leached by cyanidation is stored for use in the cyanidation operation.

[0013] Furthermore, in step (4), dilute sulfuric acid is added in an amount of 1.2 times the theoretical amount, which is calculated based on the chemical reaction formula Cu(OH)2+H2SO4=2H2O+CuSO4.

[0014] Furthermore, in step (4), after the concentrated filtrate is collected, iron powder is added and stirred for 15-20 minutes to allow the replacement reaction in the liquid to be sufficient.

[0015] Further, in step (4), iron powder is added to the stirring barrel, and the iron powder is reacted according to the chemical reaction equation Cu 2+ +Fe=Cu+Fe 2+ Add 1.2-1.5 times the theoretical amount for control.

[0016] The invention provides a method for recovering gold, silver and copper from sulfur concentrate roasted sand washing waste liquid. The method comprises the following steps: using cheap lime to prepare lime milk, adding the lime milk into the washing waste liquid, controlling the end point pH value to be 7-8, performing solid-liquid separation after complete precipitation, recycling the water for use in production, and recovering gold, silver and copper from the precipitated residue containing gold, silver and copper respectively; firstly, recovering gold and silver by cyanidation, controlling the rotation speed at 300-500 revolutions per minute during the cyanidation process, and then recovering copper by using an acid leaching method for replacing copper with iron.

[0017] The innovation of the present invention is:

[0018] (1) Use lime milk to precipitate and collect the insoluble solid fine particles of gold and silver and copper ions, so as to enrich the gold, silver and copper in the washing wastewater to a greater extent, thus laying a foundation for the subsequent recovery of gold, silver and copper. The operation is simple and the cost is relatively low.

[0019] (2) treating the precipitated residue by cyanide leaching to recover gold and silver, and then recovering copper by acid leaching of iron to replace copper;

[0020] (3) The rotation speed during cyanidation is controlled at 300-500 rpm;

[0021] (4) Grinding the slag after gold and silver extraction before acid leaching of copper;

[0022] (5) Compared with other methods, the recovery rates of gold, silver and copper in the present invention are significantly improved, and the amount of sodium cyanide used is small. Specifically, a) the cyanide leaching rate of gold and silver is high, with the gold leaching rate reaching more than 90% and the silver leaching rate reaching more than 86%. At the same time, the unit consumption of sodium cyanide is low, about 2.5 kg / t; b) the acid leaching copper process has a high copper recovery rate of more than 76%.

[0023] The possible reasons are as follows: (1) When lime milk is used to precipitate and collect the insoluble solid fine particles of gold and silver and copper ions, the generated iron hydroxide, copper hydroxide, and calcium sulfate with large crystal particles are completely precipitated. Iron hydroxide is an amorphous precipitate or colloidal precipitate with a large surface area and strong adsorption capacity. It can adsorb and precipitate the insoluble solid fine particles of gold and silver in the waste liquid, so that gold and silver are enriched in the precipitate residue. The precipitate particles are irregularly stacked and loose, which is conducive to the recovery of gold and silver in the later stage. At the same time, the large crystal particles of calcium sulfate will absorb and enclose copper ions and copper hydroxide flocs during the precipitation process, so that the copper in the liquid is enriched in the precipitate residue.

[0024] (2) During the cyanidation process, the rotation speed is controlled at 300-500 rpm to avoid the copper absorbed and sandwiched by calcium sulfate from reacting with cyanide after being crushed, thus saving sodium cyanide. Because in the process of gold and silver cyanidation leaching, sodium cyanide will react with copper first in the presence of copper, causing a sharp increase in the amount of sodium cyanide used. Cyanidation leaching can avoid the reaction of copper with sodium cyanide by first absorbing and sandwiching copper with calcium sulfate, thereby reducing the amount of sodium cyanide used.

[0025] (3) Before acid leaching of copper, the slag after gold and silver extraction is ground to expose or release the copper absorbed and trapped by calcium sulfate to react with acid, thereby effectively recovering the copper and improving the copper recovery rate.

[0026] Positive effects compared to existing methods

[0027] (1) Provide an effective method for recovering gold, silver and copper from the wastewater of sulfur concentrate roasted sand washing with low gold, silver and copper content. This method can enrich the gold, silver and copper in the wastewater of washing to a greater extent, thus laying a foundation for the subsequent recovery of gold, silver and copper, which is a very critical point;

[0028] (2) The cyanide leaching rate of gold and silver is high, with the gold leaching rate reaching more than 90% and the silver leaching rate reaching more than 86%. At the same time, the unit consumption of sodium cyanide is low, about 2.5kg / t, and the types of reagents used are relatively few, and the reagent cost is low. The reagents used in this process are all common chemical reagents, which are easy to obtain;

[0029] (3) Acid leaching copper process, with a high copper recovery rate of over 76%;

[0030] (4) The processing equipment and process flow are simple and the operation is easy to control. The equipment used in the process has a simple structure and is easy to realize automatic control;

[0031] (5) The recycling cost is low and the economic value is considerable.

[0032] The innovative point of this recovery method is not the cyanidation process of gold and silver, nor the acid leaching process of copper, but the clever use of the characteristics of hydroxide precipitation and sulfate precipitation to enrich low-content gold, silver and copper in the washing waste liquid, and recover gold, silver and copper in combination with the existing cyanidation process and acid leaching copper process. If gold, silver and copper are not enriched, it is difficult to recycle them using existing methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a device connection diagram of the present invention;

[0034] Among them, 1: No. 1 waste liquid pool, 2: delivery pump, 3: No. 1 mixing barrel, 4: No. 1 inclined plate thickener; 5: No. 1 filter press, 6: No. 2 mixing barrel, 7: No. 1 leaching tank, 8: No. 2 leaching tank, 9: No. 2 inclined plate thickener, 10: No. 2 filter press, 11: stirring ball mill, 12: No. 3 mixing barrel, 13: No. 3 inclined plate thickener, 14: No. 3 filter press, 15: No. 4 mixing barrel, 16: No. 4 inclined plate thickener, 17: No. 4 filter press, 18: No. 1 water storage tank, 19: No. 2 water storage tank, 20: No. 3 water storage tank. DETAILED DESCRIPTION

[0035] like Figure 1The system shown in the figure recovers gold, silver and copper from the waste liquid of sulphur concentrate roasting sand washing, comprises a waste liquid pool 1 No. 1, which is connected to the feed port of a mixing barrel 3 No. 1 through a delivery pump; the overflow outlet at the upper end of the mixing barrel 3 is connected to the feed port of a sloping plate thickener 4 No. 1 through a delivery pump, the thick slurry outlet at the bottom of the sloping plate thickener 4 No. 1 is connected to the feed port of a filter press 5 No. 1, the filtrate outlets of the sloping plate thickener 4 No. 1 and the filter press 5 No. 1 are connected to a water storage tank 18; the precipitated residue outlet of the filter press 5 No. 1 is connected to the feed port of a mixing barrel 6 No. 2 The upper overflow outlet of the No. 2 stirring barrel 6 is connected to the feed port of the No. 1 leaching tank 7, the upper overflow outlet of the No. 1 leaching tank 7 is connected to the feed port of the No. 2 leaching tank 8, the upper overflow outlet of the No. 2 leaching tank 8 is connected to the No. 2 inclined plate thickener 9 through a delivery pump, and the positions of the No. 2 stirring barrel 6, the No. 1 leaching tank 7, and the No. 2 leaching tank 8 are successively lowered; the No. 2 leaching tank 8 is provided with a carbon extraction pump, the upper end of which extends into the No. 1 leaching tank 7 through a pipeline, and the No. 1 leaching tank 7 is provided with a carbon extraction pump, and the upper end of the carbon extraction pump in the No. 1 leaching tank 7 is connected to the No. 2 leaching tank 8 through a pipeline. The external gold-loaded carbon analysis and purification system is connected; the bottom thick slurry outlet of the No. 2 inclined plate thickener 9 is connected to the feed port of the No. 2 filter press 10, and the filtrate outlets of the No. 2 inclined plate thickener 9 and the No. 2 filter press 10 are connected to the No. 2 water storage tank 19; the precipitate outlet of the No. 2 filter press 10 is connected to the feed port of the stirring ball mill 11; the discharge port of the stirring ball mill 11 is connected to the No. 3 stirring barrel 12 through a delivery pump, the overflow outlet at the upper end of the No. 3 stirring barrel 12 is connected to the No. 3 inclined plate thickener 13 through a delivery pump, and the bottom thick slurry outlet of the No. 3 inclined plate thickener 13 is connected to the No. 3 The feed port of filter press 14 is connected, the precipitated slag of filter press 14 is stored for treatment, the filtrate outlets of No. 3 inclined plate thickener 13 and No. 3 filter press 14 are connected to the feed port of No. 4 mixing barrel 15; the overflow outlet at the upper end of No. 4 mixing barrel 15 is connected to the feed port of No. 4 inclined plate thickener 16 through a conveying pump, and the bottom thick slurry outlet of No. 4 inclined plate thickener 16 is connected to the feed port of No. 4 filter press 17, the precipitated slag of No. 4 filter press 17 is copper concentrate, and the filtrate outlets of No. 4 inclined plate thickener 16 and No. 4 filter press 17 are connected to No. 3 water storage tank 17.

[0036] Furthermore, the carbon lifting pump is an air lift; the delivery pump is a slurry pump; lime milk is added to the No. 1 mixing barrel 3; lime milk is added to the No. 2 mixing barrel 6; sodium cyanide is added to the No. 1 leaching tank 7; activated carbon is added to the No. 2 leaching tank 8; dilute sulfuric acid is added to the No. 3 mixing barrel 12; and iron powder is added to the No. 4 mixing barrel 15.

[0037] A method for recovering gold, silver and copper from sulfur concentrate roasted sand washing waste liquid, comprising the following steps: (1) detecting the content of gold, silver and copper in the sulfur concentrate roasted sand washing waste liquid, wherein the sulfur concentrate roasted sand washing waste liquid mainly contains gold, silver, copper and iron ions, and the sulfur concentrate roasted sand washing waste liquid is hereinafter referred to as waste liquid; (2) enriching and precipitating the gold, silver and copper in the waste liquid; placing the waste liquid in a stirring barrel and adding a lime milk solution to stir, controlling the pH value at 7-8 after the reaction is complete, and then performing solid-liquid separation; (3) recovering gold and silver; slurrying the filter residue obtained in step (2) to obtain a slurry with a concentration of 30-40%, and then adding the lime milk solution to stir, and controlling the pH value at 10-11, sodium cyanide is added to the slurry after the reaction for leaching, and then activated carbon is added to adsorb gold and silver; wherein, when the lime milk solution is added and stirred, the stirring speed needs to be controlled at 300-500 revolutions per minute to prevent the copper adsorbed and trapped by calcium sulfate from reacting with cyanide, and the gold and silver carbon is sent to desorption and purification to recover gold and silver; (4) copper recovery process, the slurry treated in step (3) is subjected to solid-liquid separation, and the filter residue is subjected to grinding treatment; the grinding concentration is controlled at 50-60%, and dilute sulfuric acid is added for acid leaching treatment, and the slurry after acid leaching is subjected to solid-liquid separation; the filtrate is added with iron powder for reaction, and the slurry after the reaction is concentrated and filtered again, and the filter residue is copper concentrate.

[0038] Furthermore, the mass fraction of the lime milk solution added in step (2) is 10-15%, the pH value is controlled at 7-8, the amount of lime milk solution added is measured by a pH meter, and the stirring time is 5-8 minutes to allow the chemical reaction in the liquid to be sufficient.

[0039] Furthermore, in step (3), a lime milk solution having a mass fraction of 10-15% is added and stirred, the pH value is controlled at 10-11, the amount of addition is determined by a pH meter, and the alkali leaching is performed for more than 30 minutes.

[0040] Furthermore, in step (4), the concentrated filtered water from the slurry from which gold and silver are leached by cyanidation is stored for use in the cyanidation operation.

[0041] Furthermore, in step (4), dilute sulfuric acid is added in an amount of 1.2 times the theoretical amount, which is calculated based on the chemical reaction formula Cu(OH)2+H2SO4=2H2O+CuSO4.

[0042] Furthermore, in step (4), after the concentrated filtrate is collected, iron powder is added and stirred for 15-20 minutes to allow the replacement reaction in the liquid to be sufficient.

[0043] Further, in step (4), iron powder is added to the stirring barrel, and the iron powder is reacted according to the chemical reaction equation Cu 2+ +Fe=Cu+Fe 2+ Add 1.2-1.5 times the theoretical amount for control.

[0044] Embodiment 1:

[0045] A sulfur concentrate roasted sand washing waste liquid, the solution pH = 4.2, the useful metal element content: gold 0.038 mg / L, silver 0.091 mg / L, copper 160 mg / L, iron 320 mg / L.

[0046] The present invention is used to recover gold, silver and copper from the sulfur concentrate roasting sand washing wastewater, and the implementation technical scheme includes:

[0047] (1) Detection of gold, silver and copper content in sulfur concentrate roasted sand washing wastewater. Take a certain amount of the washing wastewater to be treated and determine the content of gold, silver, copper and other elements respectively;

[0048] (2) Enriching gold, silver and copper in the wastewater from the sedimentation water washing; pumping the wastewater from the wastewater pool No. 1 containing gold, silver and copper to the mixing barrel No. 1, then adding 10% lime milk solution to the mixing barrel No. 1, controlling the pH value at 7, and measuring the amount of addition by a pH meter. The stirring time is 5 minutes to allow the chemical reaction in the liquid to be sufficient, and then pumping it to the No. 1 inclined plate thickener, filtering the bottom flow, and returning the filtered water and the overflow water of the No. 1 inclined plate thickener to the production cycle. The filter residue is conveyed to the No. 2 mixing barrel by a belt for slurry treatment. Through this treatment step, the removal rate of gold, silver and copper in the wastewater is relatively high, basically reaching 98%. At the same time, the enrichment ratio of gold, silver and copper in the filter residue is high, with a gold grade of 6.2g / t, a silver grade of 18g / t and a copper grade of 3.1%;

[0049] (3) Process for recovering gold and silver. The precipitated slag in the No. 2 stirring barrel is slurried to a concentration of 30%, and then a lime milk solution with a mass fraction of 10% is added. The pH value is controlled at 10, and the amount of addition is measured by a pH meter. After alkali leaching for 30 minutes, the slurry in the No. 2 stirring barrel flows into the No. 1 leaching tank by gravity. Sodium cyanide solution is added to the No. 1 leaching tank for cyanide leaching. The amount of sodium cyanide is 2.5 kg / t. The slurry in the No. 1 stirring leaching tank flows to the No. 2 stirring leaching tank by gravity, and activated carbon is added to the No. 2 leaching tank to adsorb gold and silver. The total leaching time is 24 hours. Note that the stirring speed must be controlled at 500 rpm to avoid the copper absorbed and trapped by calcium sulfate from reacting with cyanide after being crushed. The gold and silver carbon is sent to desorption and purification to recover gold and silver.

[0050] (4) Copper recovery process. The slurry from which gold and silver are leached by cyanidation is pumped to the No. 2 inclined plate thickener, where the bottom flow is filtered, and the filter press water and the overflow water of the No. 2 inclined plate thickener are stored for use in the cyanidation operation. The filter press residue is conveyed to the stirred mill by a belt for grinding. The grinding concentration is controlled at 50%. The discharge of the mill is pumped to the No. 3 mixing barrel, and then dilute sulfuric acid is added. The amount added is 1.2 times the theoretical amount. The theoretical amount is calculated based on the chemical reaction formula Cu(OH)2+H2SO4=2H2O+CuSO4. The acid leaching time is 5 hours. Then the slurry in the No. 3 mixing barrel is pumped to the No. 3 inclined plate thickener, where the bottom flow is filtered, and the filter press residue is stored. The filter press water and the overflow water of the No. 3 inclined plate thickener are pumped to the No. 4 mixing barrel, and iron powder is added to the mixing barrel. The iron powder is calculated based on the chemical reaction formula Cu(OH)2+H2SO4=2H2O+CuSO4. 2+ +Fe=Cu+Fe 2+ The addition amount is controlled at 1.2 times of the theoretical amount, and the stirring time is 15 minutes to allow the replacement reaction in the liquid to be sufficient. It is then pumped to No. 4 inclined plate thickener, and the bottom flow is filtered. The filter press water and the overflow water of No. 4 inclined plate thickener are stored for use in grinding operations. The filter press residue is copper concentrate and can be sold directly.

[0051] This treatment method was adopted and implemented in this case, and the results were as follows: gold leaching rate: 91.02%, silver leaching rate: 88%, and copper concentrate with a grade of 80% and a recovery rate of 78%.

[0052] Comparative Example 1.1:

[0053] In Example 1, the stirring speed in step (3) was adjusted to 900 revolutions per minute for a comparative test, and other process conditions were the same. The test index results are shown in Table 1:

[0054] Comparative Example 1.2:

[0055] In Example 1, the filter press residue after cyanidation in step (4) was not ground as a comparative test, and other process conditions were the same. The test index results are shown in Table 1:

[0056] Table 1. Recovery of gold, silver and copper using Comparative Example 1.1 and Comparative Example 1.2

[0057] Comparative Example Test conditions Gold leaching rate, % Silver leaching rate, % Copper recovery rate, % Comparative Example 1.1 Stirring speed 900 rpm 78.62 50.25 65.73 Comparative Example 1.2 Cyanide slag unground 91.26 87.59 3.24

[0058] The results show that in Comparative Example 1.1, only the stirring speed in step (3) is adjusted to 900 rpm. Due to the high stirring speed, the filter press residue obtained in step (2) is scrubbed during the high-speed stirring process, so that part of the copper absorbed and sandwiched by calcium sulfate is exposed. The copper contacts and reacts with the sodium cyanide solution, consumes free cyanide, and reduces the cyanide concentration of the cyanide operation, thereby causing the leaching rate of gold and silver to decrease. In addition, copper dissolves during the cyanidation process, and the copper recovery rate in the later stage is also affected.

[0059] In Comparative Example 1.2, only the condition of not grinding the cyaniding slag in step (4) was changed. This condition was after the cyaniding operation, so the leaching rates of gold and silver were not affected, but the recovery rate of copper decreased significantly. The main reason was that the cyaniding slag was not ground, and the copper absorbed and trapped by calcium sulfate could not be fully dissociated and exposed to react with sulfuric acid and dissolved in the liquid phase, resulting in poor copper recovery effect.

[0060] Embodiment 2:

[0061] A sulfur concentrate roasted sand washing waste liquid, the solution pH = 3.6, the useful metal element content: gold 0.021mg / L, silver 0.062mg / L, copper 120mg / L, iron 380mg / L.

[0062] The present invention is used to treat the metal smelting acid wastewater containing arsenic, iron and other metals, and the implementation technical scheme includes:

[0063] (1) Detection of gold, silver and copper content in sulfur concentrate roasted sand washing wastewater. Take a certain amount of the washing wastewater to be treated and determine the content of gold, silver, copper and other elements respectively;

[0064] (2) Enriching gold, silver and copper in the wastewater from the sedimentation water washing; pumping the wastewater from the wastewater pool No. 1 containing gold, silver and copper to the mixing barrel No. 1, then adding 15% lime milk solution to the mixing barrel No. 1, controlling the pH value at 8, and measuring the amount of addition by a pH meter. The stirring time is 8 minutes to allow the chemical reaction in the liquid to be sufficient, and then pumping it to the No. 1 inclined plate thickener, filtering the bottom flow, and returning the filtered water and the overflow water of the No. 1 inclined plate thickener to the production cycle. The filter residue is conveyed to the No. 2 mixing barrel by a belt for slurry treatment. Through this treatment step, the removal rate of gold, silver and copper in the wastewater is relatively high, basically reaching 98%. At the same time, the enrichment ratio of gold, silver and copper in the filter residue is high, with a gold grade of 3.94 g / t, a silver grade of 11.23 g / t, and a copper grade of 2.36%;

[0065] (3) Process for recovering gold and silver. The precipitated slag in the No. 2 stirring barrel is slurried to a concentration of 40%, and then a lime milk solution with a mass fraction of 15% is added. The pH value is controlled at 11. The amount of addition is measured by a pH meter. After alkali leaching for 30 minutes, the slurry in the No. 2 stirring barrel flows by gravity into the No. 1 stirring leaching tank. Sodium cyanide solution is added to the No. 1 stirring leaching tank for cyanide leaching. The amount of sodium cyanide is 2.5 kg / t. The slurry in the No. 1 stirring leaching tank flows by gravity into the No. 2 stirring leaching tank, and activated carbon is added to the No. 2 stirring leaching tank to adsorb gold and silver. The total leaching time is 24 hours. Note that the stirring speed must be controlled at 300 rpm (if the speed is lower than 300 rpm, the slurry will sink to the bottom and the leaching effect will deteriorate) to avoid the copper absorbed and trapped by calcium sulfate from reacting with cyanide after being crushed. The gold and silver carbon is sent to desorption and purification to recover gold and silver;

[0066] (4) Copper recovery process. The slurry from which gold and silver are leached by cyanidation is pumped to the No. 2 inclined plate thickener, where the bottom flow is filtered, and the filter press water and the overflow water of the No. 2 inclined plate thickener are stored for use in the cyanidation operation. The filter press residue is conveyed to the stirred mill by a belt for grinding. The grinding concentration is controlled at 60%. The discharge of the mill is pumped to the No. 3 mixing barrel, and then dilute sulfuric acid is added. The amount added is 1.2 times the theoretical amount. The theoretical amount is calculated based on the chemical reaction formula Cu(OH)2+H2SO4=2H2O+CuSO4. The acid leaching time is 5 hours. Then the slurry in the No. 3 mixing barrel is pumped to the No. 3 inclined plate thickener, where the bottom flow is filtered, and the filter press residue is stored. The filter press water and the overflow water of the No. 3 inclined plate thickener are pumped to the No. 4 mixing barrel, and iron powder is added to the mixing barrel. The iron powder is calculated based on the chemical reaction formula Cu(OH)2+H2SO4=2H2O+CuSO4. 2+ +Fe=Cu+Fe 2+ 1.5 times of the theoretical amount is added for control and the stirring time is 20 minutes to allow the replacement reaction in the liquid to be sufficient. It is then pumped to No. 4 inclined plate thickener and the bottom flow is filtered. The filter press water and the overflow water of No. 4 inclined plate thickener are stored for use in grinding operations. The filter press residue is copper concentrate and can be sold directly.

[0067] This treatment method was adopted and implemented in this case, and the results were as follows: gold leaching rate: 90.05%, silver leaching rate: 86.13%, and copper concentrate with a grade of about 78.96% and a recovery rate of 76.32% was obtained.

[0068] Comparative Example 2.1:

[0069] In Example 1, the stirring speed in step (3) was adjusted to 1100 rpm for a comparative test, and other process conditions were the same. The test index results are shown in Table 2:

[0070] Comparative Example 2.2:

[0071] In Example 1, the filter press residue after cyanidation in step (4) was not ground as a comparative test, and other process conditions were the same. The test index results are shown in Table 2:

[0072] Table 2. Recovery of gold, silver and copper using Comparative Example 2.1 and Comparative Example 2.2

[0073] Comparative Example Test conditions Gold leaching rate, % Silver leaching rate, % Copper recovery rate, % Comparative Example 2.1 Stirring speed 1100 rpm 74.36 45.20 60.29 Comparative Example 2.2 Cyanide slag unground 90.14 86.32 3.08

[0074] It can be seen from the results that in Comparative Example 2.1, only the stirring speed in step (3) is adjusted to 1100 rpm. Due to the high stirring speed, the filter press residue obtained in step (2) is scrubbed during the high-speed stirring process, so that part of the copper absorbed and sandwiched by calcium sulfate is exposed, and the copper contacts and reacts with the sodium cyanide solution to consume free cyanide, thereby reducing the cyanide concentration of the cyanide operation, thereby causing the leaching rate of gold and silver to decrease. In addition, copper dissolves during the cyanidation process, and the copper recovery rate in the later stage is also affected.

[0075] In Comparative Example 2.2, only the condition of not grinding the cyaniding slag in step (4) was changed. This condition was after the cyaniding operation, so the leaching rates of gold and silver were not affected, but the recovery rate of copper decreased significantly. The main reason was that the cyaniding slag was not ground, and the copper absorbed and trapped by calcium sulfate could not be fully dissociated and exposed to react with sulfuric acid and dissolved in the liquid phase, resulting in poor copper recovery effect.

Claims

1. A method for recovering gold, silver and copper from sulfur concentrate roasted sand washing wastewater, characterized in that: The following steps are involved: (1) Detection of gold, silver and copper content in sulfur concentrate roasting sand washing wastewater. The sulfur concentrate roasting sand washing wastewater mainly contains gold, silver, copper and iron ions. The sulfur concentrate roasting sand washing wastewater is hereinafter referred to as wastewater; (2) Enriching and precipitating gold, silver and copper in the waste water of washing; placing the waste water in a stirring barrel, adding lime milk solution and stirring, controlling the pH value at 7-8 after the reaction is complete, and then performing solid-liquid separation; (3) Process for recovering gold and silver: the filter residue obtained in step (2) is slurried to obtain a slurry with a concentration of 30-40%, and then a lime milk solution is added and stirred, and the pH value is controlled at 10-11. After the reaction, sodium cyanide is added to the slurry for leaching, and then activated carbon is added to adsorb gold and silver. When the lime milk solution is added and stirred, the stirring speed needs to be controlled at 300-500 revolutions per minute to prevent the copper adsorbed and sandwiched by calcium sulfate from reacting with cyanide, and the gold and silver carbon is sent to desorption and purification to recover gold and silver; (4) Copper recovery process, the ore pulp treated in step (3) is subjected to solid-liquid separation, and the filter residue is subjected to grinding treatment; the grinding concentration is controlled at 50-60%, dilute sulfuric acid is added for acid leaching, and the ore pulp after acid leaching is subjected to solid-liquid separation; the filtrate is added with iron powder for reaction, and the ore pulp after the reaction is concentrated and filtered again, and the filter residue is the copper concentrate.

2. The method for recovering gold, silver and copper from sulfur concentrate roasting wastewater washing according to claim 1, characterized in that: The mass fraction of the lime milk solution added in step (2) is 10-15%, the pH value is controlled at 7-8, the amount of lime milk solution added is measured by a pH meter, and the stirring time is 5-8 minutes to allow the chemical reaction in the liquid to be sufficient.

3. The method for recovering gold, silver and copper from sulfur concentrate roasting wastewater according to claim 1, characterized in that: In step (3), 10-15% lime milk solution is added and stirred, the pH value is controlled at 10-11, the amount added is determined by a pH meter, and the alkali leaching is performed for more than 30 minutes.

4. The method for recovering gold, silver and copper from sulfur concentrate roasting waste water washing liquid as claimed in claim 1, characterized in that: In step (4), the slurry from which gold and silver are leached by cyanidation is densely filtered and stored for use in the cyanidation operation.

5. The method for recovering gold, silver and copper from sulfur concentrate roasting wastewater washing according to claim 1, characterized in that: In step (4), dilute sulfuric acid is added in an amount of 1.2 times the theoretical amount, which is calculated based on the chemical reaction formula Cu(OH)2+H2SO4=2H2O+CuSO4.

6. The method for recovering gold, silver and copper from sulfur concentrate roasting wastewater washing according to claim 1, characterized in that: In step (4), after the concentrated filtrate is collected, iron powder is added and stirred for 15-20 minutes to allow the replacement reaction in the liquid to be sufficient.

7. The method for recovering gold, silver and copper from sulfur concentrate roasting wastewater washing according to claim 1, characterized in that: In step (4), iron powder is added to the mixing tank, and the iron powder is reacted according to the chemical reaction equation Cu 2+ +Fe=Cu+Fe 2+ Add 1.2-1.5 times the theoretical amount for control.

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