Method for preparing cuprous thiocyanate by using fire refining slag of copper

Abstract

The invention discloses a method for preparing cuprous thiocyanate by using copper fire refining slag, and relates to the technical field of copper fire refining. According to the method, the copper pyrogenic process refining slag meeting the specific content composition is subjected to chlorination leaching, the refining slag is leached through hydrochloric acid system chlorine salt to obtain the leachate containing the cuprous, then thiocyanate is added for a reaction, and the product cuprous thiocyanate can be obtained. The synthetic route provided by the invention is low in cost and high in product rate, the leaching slag can be returned to prepare nickel matte, and high-value utilization of the copper refining slag is realized.

Description

Technical Field

[0001] This invention relates to the field of copper pyrometallurgical refining technology, and more specifically, to a method for preparing cuprous thiocyanate using copper pyrometallurgical refining slag. Background Technology

[0002] Enterprises that use copper-containing scrap materials such as copper-plating sludge, waste electronic circuit boards, and scrap copper as raw materials to recycle metal resources through pyrometallurgy will generate a large amount of refining slag during the entire pyrometallurgical refining process. This copper pyrometallurgical refining slag is enriched with a large amount of metals such as Cu, Ni, Sn, As, Pb, and Sb, and most of them exist in oxide phases, with a small portion existing in elemental or alloy phases.

[0003] Because refining slag has a high copper content, it is an important secondary raw material for copper recycling. It is generally returned to the converter for cold smelting, or smelted together with concentrate in a blast furnace or reverberatory furnace. The resulting black copper is then refined by pyrometallurgical methods and electrolytic refining to produce cathode copper. For example, CN113652552A uses wet leaching, with the leachate used as the black copper electrolyte, and the leaching slag returned to reduction smelting to prepare black copper anode plates; CN202411901395.2 addresses high-nickel refining slag by first subjecting it to weak acid arsenic removal, followed by sulfuric acid leaching of copper, with the leachate used as the electrolyte, and the leaching slag used as a raw material for preparing low-grade nickel matte. However, the copper-containing solutions obtained by the above methods can only be used as electrolytes and cannot directly realize the commercialization of copper products.

[0004] Therefore, there is an urgent need to develop a new copper pyrometallurgical slag recovery process to produce commercially viable copper products.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing cuprous thiocyanate using copper pyrometallurgical refining slag, with the aim of using copper pyrometallurgical refining slag to prepare high-value-added copper products.

[0007] This invention is implemented as follows: In a first aspect, the present invention provides a method for preparing cuprous thiocyanate using copper pyrometallurgical refining slag, comprising: The copper pyrometallurgical refining slag is provided: The copper pyrometallurgical refining slag contains Cu2O phase, metallic copper phase and CuO phase, and the content of each phase satisfies the following order: Cu2O phase > metallic copper phase > CuO phase; Chlorination leaching: Copper pyrometallurgical refining slag is leached using a mixed solution containing hydrochloric acid and chloride salts to obtain leaching solution and leaching residue; Synthesis of cuprous thiocyanate: The leachate and thiocyanate are mixed and reacted.

[0008] In an optional embodiment, the mixed solution used in the chlorination leaching process is obtained by mixing chloride salt and hydrochloric acid aqueous solution, with the amount of hydrochloric acid being more than 1.5 times the theoretical molar amount, the total chlorine content in the mixed solution being 3.5 mol / L-5.5 mol / L, and the amount of mixed solution used per kilogram of copper pyrometallurgical refining slag being 5L-15L. The theoretical molar amount of hydrochloric acid is equal to the molar amount of copper added to the refining slag.

[0009] In an optional embodiment, the chloride salt is selected from at least one of sodium chloride, potassium chloride, and ammonium chloride; Preferably, the amount of hydrochloric acid used is 1.85-2.35 times the theoretical molar amount; Preferably, the leaching time is 1 min to 60 min, and more preferably 2 min to 10 min.

[0010] In an optional embodiment, the copper pyrometallurgical refining slag is first crushed and finely ground before being chlorinated and leached, and the grinding fineness is controlled to ensure that the mass percentage of particles with a diameter less than 0.150 mm is greater than 75%.

[0011] In an optional embodiment, the reaction with thiocyanate includes: heating the leaching solution to above 50°C, then adding thiocyanate and reacting for 10-60 minutes. After the reaction is complete, solid-liquid separation is performed to obtain solid material and copper-free liquid. The obtained solid material is washed and dried to obtain cuprous thiocyanate product. Preferably, during the reaction with thiocyanate, the reaction temperature is controlled at 70℃-80℃ and the reaction time is 20min-30min; Preferably, the washing process includes: first washing with a corresponding chloride salt solution, followed by rinsing with water.

[0012] In an optional embodiment, the thiocyanate is selected from at least one of sodium thiocyanate, potassium thiocyanate, and ammonium thiocyanate. Preferably, the cation in the thiocyanate is the same as the cation in the chloride salt used.

[0013] In an optional implementation, the ratio of the amount of thiocyanate used to the theoretical amount is (0.95-1.00):1, wherein the theoretical amount of thiocyanate is calculated based on the principle that 1 mol of thiocyanate ions equals 1 mol of monovalent copper.

[0014] In an optional embodiment, when the arsenic content in the copper removal solution is greater than 10 g / L, arsenic precipitation is performed using ferric chloride to obtain a purified solution and a purified residue, and the purified solution is returned to the chlorination leaching stage.

[0015] In an optional embodiment, during the arsenic precipitation treatment, the amount of ferric chloride used is 1.0-1.3 times its theoretical amount, the pH value is controlled at 3-7, and the reaction time is 30-120 min; wherein the theoretical amount of ferric chloride is calculated based on 1 mol of iron equaling 1 mol of total arsenic.

[0016] In an optional embodiment, the leaching residue is subjected to reduction sulfidation smelting, and the impurity-removed residue is returned to the reduction sulfidation smelting stage; Preferably, during the reduction sulfidation smelting process, the smelting temperature is controlled at 1200℃-1300℃, the mass ratio of coke to slag to be treated is (15-20):100, and the flow temperature of the FeO-CaO-SiO2 ternary slag system is 1100℃-1200℃, resulting in low-grade nickel matte and antimony-tin dust.

[0017] This invention offers the following advantages: It involves chlorinating copper pyrometallurgical refining slag that meets specific compositional requirements, using a hydrochloric acid system to leach the slag with chloride salts to obtain a leachate containing monovalent copper. Further reaction with thiocyanate yields cuprous thiocyanate. The synthetic route provided by this invention is low-cost, has a high yield, and the leaching slag can be recycled for nickel matte production, achieving high-value utilization of copper refining slag. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The process flow diagram for preparing cuprous thiocyanate using copper pyrometallurgical refining slag provided by this invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] Cuprous thiocyanate, an excellent inorganic pigment, is typically prepared by reducing copper sulfate to monovalent copper using sodium sulfite or sulfur dioxide, followed by reaction with sodium thiocyanate or potassium thiocyanate. This process requires prior reduction to monovalent copper before conversion to cuprous thiocyanate, and the preparation cost is relatively high. This invention achieves high-value utilization of copper refining slag while also solving the problem of low preparation cost in traditional cuprous thiocyanate production, demonstrating excellent prospects for industrial application.

[0022] Please refer to Figure 1 This invention provides a method for preparing cuprous thiocyanate using copper pyrometallurgical refining slag, the steps of which are as follows: S1, Provide copper pyrometallurgical refining slag In the copper pyrometallurgical refining slag, the copper phases are mainly Cu2O and Cu, with small amounts of CuO and other copper phases (such as CuO·Fe2O3, CuO·SiO2). The content of each phase—Cu2O, metallic copper, and CuO—satisfies the following order: Cu2O > metallic copper > CuO, to ensure that a monovalent copper leachate is obtained after chlorination leaching. Preferably, the content of Cu phase is greater than the content of CuO and other copper phases.

[0023] S2, Crushing and Fine Grinding The copper pyrometallurgical refining slag is crushed and finely ground to improve the leaching rate during chlorination leaching.

[0024] In some embodiments, by adjusting parameters such as the crushing and fine grinding time, the grinding fineness is made such that the mass percentage of particles with a diameter less than 0.150 mm is greater than 75%, that is, the mass percentage of particles passing through a square sieve with a side length of 0.150 mm (the 0.150 mm sieve diameter corresponds exactly to a 100 mesh sieve) reaches more than 75%.

[0025] S3, Chlorination leaching A mixed solution containing hydrochloric acid and chloride salts is prepared as the acid solution for chlorination leaching. This solution is mixed with finely ground copper pyrometallurgical refining slag for leaching. After leaching, leaching solution and leaching slag are obtained. In actual operation, the finely ground slurry is pumped to the leaching reactor or reaction tank for chlorination leaching. Copper leaching slag and leaching solution are obtained through the chlorination copper leaching process, and chloride salt leaching is performed using a hydrochloric acid system.

[0026] The leachate is a solution of monovalent copper, and in the hydrochloric acid chlorination system, the main reactions are as follows: (1); (2); (3); (4); (5); (6).

[0027] Therefore, in a total chlorine system with high acidity, copper in the refining slag is leached out, and the copper in the leachate is mainly in the form of... and It exists and reacts with thiocyanate to form cuprous thiocyanate.

[0028] In some embodiments, the mixed solution used in the chlorination leaching process is obtained by mixing chloride salt and hydrochloric acid aqueous solution. The amount of hydrochloric acid used is greater than 1.50 times the theoretical molar amount, such as 1.55 times, 1.60 times, 1.70 times, 1.80 times, 1.90 times, 2.00 times, 2.10 times, 2.20 times, 2.3 times, 2.4 times, etc., preferably 1.85 times to 2.35 times the theoretical molar amount. If the amount of hydrochloric acid is too low, the solution will be turbid, and cuprous acid will easily be oxidized to divalent copper, affecting the quality and whiteness of the subsequent synthesis of cuprous thiocyanate product; if the amount of hydrochloric acid is too high, too many impurities will be leached, affecting the synthesis process of cuprous thiocyanate product, and the reagent cost will be high.

[0029] The theoretical molar amount of hydrochloric acid is equal to the molar amount of copper added to the refining slag.

[0030] Furthermore, the total chlorine content in the mixed solution is 3.5 mol / L-5.5 mol / L, such as 3.5 mol / L, 4.0 mol / L, 4.5 mol / L, 5.0 mol / L, 5.5 mol / L, etc. "Total chlorine content" includes the chlorine content introduced by both chloride salts and hydrochloric acid. If the total chlorine content is too low, the copper leaching rate will be low; if the total chlorine content is too high, the reagent cost will be high, and there will be more impurities. The volume of mixed solution used per kilogram of copper pyrometallurgical refining slag is 5L-15L, such as 5L, 8L, 10L, 13L, 15L, etc.

[0031] In some embodiments, the chloride salt is selected from at least one of sodium chloride, potassium chloride, and ammonium chloride, and the chloride salt can be any one or more of the above. The leaching time is 1 min-60 min, such as 1 min, 2 min, 5 min, 8 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, etc., preferably 2 min-10 min. The chlorination leaching process provided in this embodiment of the invention can be carried out at room temperature (15℃-35℃) with a relatively fast reaction rate. The copper leaching rate is ≥86%, ensuring a product yield of over 80%. The copper-nickel molar ratio in the copper leaching slag is 1.5-4, and the arsenic content is less than 0.7%, which can be used as a raw material for the preparation of nickel matte.

[0032] S4, Synthesis of cuprous thiocyanate The leachate obtained in step S3 was rapidly added with thiocyanate to synthesize cuprous thiocyanate. The copper in the leachate was mainly in the form of… and It exists and reacts with thiocyanate to form cuprous thiocyanate.

[0033] (7); (8).

[0034] In some embodiments, the reaction process with thiocyanate includes: heating the leaching solution to above 50°C (e.g., 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 90°C, etc.), then adding thiocyanate for reaction. Directly adding solid thiocyanate improves filtration performance. The reaction time is 10-60 minutes (e.g., 10-20 minutes, 30-40 minutes, 50-60 minutes, etc.). After the reaction is complete, solid-liquid separation is performed to obtain solid material and copper-free liquid. The obtained solid material is washed and dried to obtain cuprous thiocyanate product. Preferably, during the reaction with thiocyanate, the reaction temperature is controlled at 70°C-80°C, and the reaction time is 20-30 minutes. By adjusting the reaction temperature and time, the reaction is promoted to proceed fully, increasing the product yield.

[0035] In some embodiments, the thiocyanate is selected from at least one of sodium thiocyanate, potassium thiocyanate, and ammonium thiocyanate. The thiocyanate can be any one or more of the above. The cation in the thiocyanate is the same as the cation of the chloride salt used (i.e., if sodium chloride is used for leaching, then sodium thiocyanate is used to synthesize cuprous thiocyanate). The ratio of the amount of thiocyanate used to the theoretical amount is (0.95-1.00):1, such as 0.95:1, 0.96:1, 0.97:1, 0.98:1, 0.99:1, 1.00:1, etc., where the theoretical molar amount of thiocyanate is the molar amount of cuprous thiocyanate in the synthesis solution. If the amount of thiocyanate used is too low, the yield of the synthesized cuprous thiocyanate product will be low. If the amount of thiocyanate used is greater than the theoretical amount, the synthesized cuprous thiocyanate will have higher impurities and lower whiteness. If there is an excess of thiocyanate, the lead leached from the chloride salt system will react with the thiocyanate to form lead thiocyanate precipitate, which will affect the purity of the cuprous thiocyanate product.

[0036] In some embodiments, the washing process of the obtained solid material includes: first washing with a corresponding chloride salt solution, followed by water washing. The first washing with the corresponding chloride salt solution removes unreacted cuprous impurities, preventing the direct washing of cuprous ligand ions in the solution with water from hydrolyzing and forming cuprous chloride precipitate, which would affect product purity. Drying can be performed by oven drying, using low-temperature vacuum drying to obtain a product with high whiteness.

[0037] By adjusting the reaction conditions, high-whiteness, low-impurity cuprous thiocyanate can be obtained. The prepared cuprous thiocyanate product has the following characteristics: purity ≥98.5%, arsenic less than 0.0001%, lead less than 0.01%, whiteness ≥80, and product yield ≥80%.

[0038] S5, Impurity Removal The copper-removed liquid can be directly returned or, after impurity removal, returned to the chlorination leaching system, reducing reagent consumption. The impurity-removed slag is returned to the smelting system for further processing, achieving zero discharge for the entire process. Specifically, when the arsenic content in the copper-removed liquid is greater than 10 g / L, arsenic precipitation is performed using ferric chloride to obtain the impurity-removed liquid and impurity-removed slag. The impurity-removed liquid is then returned to the chlorination leaching stage, achieving zero wastewater discharge.

[0039] In some embodiments, during arsenic precipitation, the amount of ferric chloride used is 1.0-1.3 times its theoretical amount, such as 1.0 times, 1.1 times, 1.2 times, 1.3 times, etc.; the pH value is controlled at 3-7, such as 3.0, 4.0, 5.0, 6.0, 7.0, etc.; and the reaction time is 30 min-120 min, such as 30 min, 60 min, 80 min, 100 min, 120 min, etc.

[0040] Furthermore, the leaching residue is subjected to reduction sulfidation smelting, and the impurity-removed slag is returned to the reduction sulfidation smelting stage, achieving zero emissions for the entire process. Reduction sulfidation smelting involves mixing and smelting the leaching residue and coke, controlling the smelting temperature at 1200℃-1300℃, such as 1200℃, 1230℃, 1250℃, 1280℃, or 1300℃. The mass ratio of coke to the slag to be treated is (15-20):100, such as 15:100, 16:100, 17:100, 18:100, 19:100, or 20:100. The flow temperature of the FeO-CaO-SiO2 ternary slag system is 1100℃-1200℃, such as 1100℃, 1130℃, 1150℃, 1180℃, or 1200℃. After smelting, low-grade nickel matte and antimony-tin dust are obtained.

[0041] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0042] Example 1 This embodiment provides a method for preparing cuprous thiocyanate using copper pyrometallurgical refining slag, the steps of which are as follows: (1) Provide copper pyrometallurgical refining slag The copper pyrometallurgical refining slag is crushed and finely ground to ensure that the mass percentage of particles with a diameter less than 0.150 mm is greater than 75%.

[0043] The main elemental composition of the obtained copper pyrometallurgical refining slag is shown in Table 1: Table 1. Elemental composition of copper pyrometallurgical refining slag

[0044] The phase analysis results of copper in copper pyrometallurgical refining slag are shown in Table 2: Table 2. Phase composition of copper in refining slag

[0045] (2) Chlorination of copper The theoretical amount of hydrochloric acid used is calculated based on the molar amount of copper added to the refining slag. A mixed solution containing hydrochloric acid and sodium chloride is prepared as the acid solution for chlorination leaching. The amount of hydrochloric acid used is 1.85 times the theoretical amount, and the total chlorine concentration is 4.0 mol / L.

[0046] The mixed solution was placed in a leaching reactor. The finely ground ore slurry was pumped to the leaching reactor for chlorination leaching. The solid-liquid ratio (S / L) was controlled at 1 kg / 7.5 L, the temperature was normal, and the reaction time was 60 min. Copper leaching slag and leachate were obtained.

[0047] Tests showed that the leachate contained 54.77 g / L of copper and 4.10 g / L of arsenic. The leaching residue contained 14.09% copper, 9.68% nickel, 4.25% antimony, and 4.14% tin.

[0048] (3) Synthesis of cuprous thiocyanate The leachate was heated to 75°C, and then sodium thiocyanate was added for a reaction time of 30 minutes. The amount of sodium thiocyanate used was 0.98 times the theoretical amount. After the reaction was complete, the solid material and the copper-removed liquid were obtained by filtration. The solid material was first washed with sodium chloride solution and then with water. The resulting cuprous thiocyanate was dried under vacuum at 72°C to obtain the cuprous thiocyanate product.

[0049] The product cuprous thiocyanate has the following specifications: purity 98.65%, arsenic less than 0.0001%, lead content 0.0057%, and whiteness 86.1.

[0050] Reduction sulfidation smelting: Leaching residue and coke are mixed and smelted at a controlled smelting temperature of 1250℃. The mass ratio of coke to slag is 17:100, and the flow temperature of the FeO-CaO-SiO2 ternary slag system is 1150℃, yielding low-grade nickel matte and antimony-tin dust. Specifications: Low-grade nickel matte contains 37.5% copper and 15% nickel; the dust contains tin and antimony. The recoveries of copper, nickel, antimony, and tin are 93%, 92%, 94%, and 90%, respectively. Example 2 This embodiment provides a method for preparing cuprous thiocyanate using copper pyrometallurgical refining slag, the steps of which are as follows: (1) Provide copper pyrometallurgical refining slag Refer to Example 1.

[0051] (2) Chlorination of copper Hydrochloric acid and sodium chloride were added to the copper-removed solution obtained in Example 1 to form the acid solution for chlorination leaching. The amount of hydrochloric acid in the solution was controlled to be 1.85 times the theoretical amount, and the total chlorine concentration was 3.5 mol / L.

[0052] The leachate was placed in a leaching reactor, and the finely ground ore slurry was pumped to the leaching reactor for chlorination leaching. The solid-liquid ratio (S / L) was controlled at 1 kg / 15 L, the temperature was normal, and the reaction time was 5 min. Copper leaching slag and leachate were obtained.

[0053] Tests showed that the leachate contained 25.87 g / L of copper and 4.12 g / L of arsenic. The leaching residue contained 17.65% copper, 8.51% nickel, 3.88% antimony, and 3.61% tin.

[0054] (3) Synthesis of cuprous thiocyanate The leachate was heated to 70°C, and then sodium thiocyanate was added for a reaction time of 30 minutes. The amount of sodium thiocyanate used was 0.95 times the theoretical amount. After the reaction was complete, the solid material and the copper-removed liquid were obtained by filtration. The solid material was first washed with potassium chloride solution and then with water. The resulting cuprous thiocyanate was dried under vacuum at 72°C to obtain the cuprous thiocyanate product.

[0055] The product cuprous thiocyanate has the following specifications: purity 98.71%, arsenic less than 0.0001%, lead content 0.0053%, and whiteness 85.8%.

[0056] Reduction sulfidation smelting: Leaching residue and coke are mixed and smelted, the smelting temperature is controlled at 1200℃, the mass ratio of coke to slag to be treated is 15:100, the flow temperature of the FeO-CaO-SiO2 ternary slag system is 1100℃, and low-grade nickel matte and antimony-tin dust are obtained. Example 3 This embodiment provides a method for preparing cuprous thiocyanate using copper pyrometallurgical refining slag, the steps of which are as follows: (1) Provide copper pyrometallurgical refining slag Refer to Example 1.

[0057] (2) Chlorination of copper Hydrochloric acid and sodium chloride were added to the copper-removed solution obtained in Example 2 as the acid solution for chlorination leaching. The amount of hydrochloric acid in the solution was controlled to be 2.35 times the theoretical amount, and the total chlorine concentration was 5.5 mol / L.

[0058] The leachate was placed in a leaching reactor, and the finely ground ore slurry was pumped to the leaching reactor for chlorination leaching. The solid-liquid ratio (S / L) was controlled at 1 kg / 5 L, the temperature was normal, and the reaction time was 60 min. Copper leaching slag and leachate were obtained.

[0059] Tests showed that the leachate contained 83.15 g / L of copper and 10.32 g / L of arsenic. The leaching residue contained 14.45% copper, 9.78% nickel, 4.32% antimony, and 4.21% tin.

[0060] (3) Synthesis of cuprous thiocyanate The leachate was heated to 80°C, and then sodium thiocyanate was added for a reaction time of 20 minutes. The amount of sodium thiocyanate used was 1.00 times the theoretical amount. After the reaction was complete, the solid material and the copper-removed liquid were obtained by filtration. The solid material was first washed with sodium chloride solution and then with water. The resulting cuprous thiocyanate was dried under vacuum at 72°C to obtain the cuprous thiocyanate product.

[0061] The product cuprous thiocyanate has the following specifications: purity 98.52%, arsenic less than 0.0001%, lead content 0.0092%, and whiteness 85.6%.

[0062] (4) Removing impurities The copper-removed solution was mixed with ferric chloride for arsenic precipitation. The amount of ferric chloride was 1.3 times the theoretical amount. The pH was controlled at 7 using sodium hydroxide solution, and the reaction was carried out at room temperature (approximately 25°C) for 120 minutes to obtain a purified solution and a purified residue. The purified solution was returned to the system for chlorination leaching, and the purified residue was returned to the reduction sulfidation smelting stage.

[0063] The purified solution contained 5.1 ppm of arsenic and 1.0 ppm of copper.

[0064] Reduction sulfidation smelting: Leaching residue and coke are mixed and smelted, the smelting temperature is controlled at 1300℃, the mass ratio of coke to slag to be treated is 20:100, the flow temperature of the FeO-CaO-SiO2 ternary slag system is 1200℃, and low-grade nickel matte and antimony-tin dust are obtained. Example 4 The only difference from Example 1 is that the amount of hydrochloric acid used in step (3) is 1.30 times the theoretical amount.

[0065] Example 5 The only difference from Example 1 is that the amount of hydrochloric acid used in step (3) is 2.5 times the theoretical amount.

[0066] Example 6 The only difference from Example 1 is that the total chlorine concentration in step (3) is 2.5 mol / L.

[0067] Example 7 The only difference from Example 1 is that the total chlorine concentration in step (3) is 6.5 mol / L.

[0068] Example 8 The only difference from Example 1 is that the reaction temperature in step (4) is 50°C.

[0069] Example 9 The only difference from Example 1 is that the reaction temperature in step (4) is 90°C.

[0070] Example 10 The only difference from Example 1 is that the amount of sodium thiocyanate used in step (4) is 1.20 times the theoretical amount.

[0071] Example 11 The only difference from Example 1 is that in step (3), sodium chloride is replaced with an equimolar amount of potassium chloride, and in step (4), sodium thiocyanate is replaced with an equimolar amount of potassium thiocyanate.

[0072] Example 12 The only difference from Example 1 is that in step (3), sodium chloride is replaced with an equimolar amount of ammonium chloride, and in step (4), sodium thiocyanate is replaced with an equimolar amount of ammonium thiocyanate.

[0073] The various indicators of the cuprous thiocyanate products prepared by the test examples and comparative examples are shown in Table 3.

[0074] Table 3. Indicators of the cuprous thiocyanate products prepared in the Examples and Comparative Examples

[0075] Note: Product yield = (molar amount of copper in cuprous thiocyanate / molar amount of copper added to the refining slag) × 100%.

[0076] The comparison between Examples 1 and Examples 6-7 shows that too low a total chlorine content will result in a low copper leaching rate and a low product yield; while too high a total chlorine content will result in more lead leaching and an increase in the lead content of the product.

[0077] A comparison of Examples 1 and 10 shows that an excess of thiocyanate leads to the precipitation of lead thiocyanate, resulting in reduced product purity, increased lead content, and an impact on whiteness.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing cuprous thiocyanate from copper pyrometallurgical refining slag, characterized in that, include: Provide copper pyrometallurgical refining slag: The copper pyrometallurgical refining slag contains Cu2O phase, metallic copper phase and CuO phase, and the content of each phase satisfies: Cu2O phase > metallic copper phase > CuO phase; Chlorination leaching: The copper pyrometallurgical refining slag is leached with a mixed solution containing hydrochloric acid and chloride salt to obtain leaching solution and leaching slag; Synthesis of cuprous thiocyanate: The leachate and thiocyanate are mixed and reacted.

2. The method according to claim 1, characterized in that, The mixed solution used in the chlorination leaching process is obtained by mixing chloride salt and hydrochloric acid aqueous solution. The amount of hydrochloric acid used is more than 1.5 times the theoretical molar amount. The total chlorine content in the mixed solution is 3.5 mol / L-5.5 mol / L. The amount of the mixed solution used per kilogram of copper pyrometallurgical refining slag is 5L-15L. The theoretical molar amount of hydrochloric acid is equal to the molar amount of copper added to the refining slag.

3. The method according to claim 2, characterized in that, The chloride salt is selected from at least one of sodium chloride, potassium chloride, and ammonium chloride; Preferably, the amount of hydrochloric acid used is 1.85-2.35 times the theoretical molar amount; Preferably, the leaching time is 1 min to 60 min, and more preferably 2 min to 10 min.

4. The method according to claim 2, characterized in that, The copper pyrometallurgical refining slag is first crushed and finely ground, and then subjected to chlorination leaching. The grinding fineness is controlled to ensure that the mass percentage of particles with a diameter less than 0.150 mm is greater than 75%.

5. The method according to claim 1, characterized in that, The reaction process with the thiocyanate includes: heating the leaching solution to above 50°C, then adding the thiocyanate and reacting for 10-60 minutes. After the reaction is complete, solid-liquid separation is performed to obtain solid material and copper-free liquid. The obtained solid material is washed and dried to obtain cuprous thiocyanate product. Preferably, during the reaction with the thiocyanate, the reaction temperature is controlled at 70℃-80℃ and the reaction time is 20min-30min; Preferably, the washing process includes: first washing with a corresponding chloride salt solution, followed by rinsing with water.

6. The method according to claim 5, characterized in that, The thiocyanate is selected from at least one of sodium thiocyanate, potassium thiocyanate, and ammonium thiocyanate; Preferably, the cation in the thiocyanate is the same as the cation in the chloride salt used.

7. The method according to claim 5, characterized in that, The ratio of the amount of thiocyanate used to the theoretical amount is (0.95-1.00):

1.

8. The method according to claim 5, characterized in that, When the arsenic content in the copper removal solution is greater than 10 g / L, arsenic precipitation is performed using ferric chloride to obtain a purified solution and a purified residue. The purified solution is then returned to the chlorination leaching stage.

9. The method according to claim 8, characterized in that, In arsenic precipitation treatment, the amount of ferric chloride used is 1.0-1.3 times its theoretical amount, the pH value is controlled at 3-7, and the reaction time is 30-120 min.

10. The method according to claim 8, characterized in that, The leaching residue is subjected to reduction sulfidation smelting, and the impurity-removed residue is returned to the reduction sulfidation smelting stage; Preferably, during the reduction sulfidation smelting process, the smelting temperature is controlled at 1200℃-1300℃, the mass ratio of coke to slag to be treated is (15-20):100, and the flow temperature of the FeO-CaO-SiO2 ternary slag system is 1100℃-1200℃, resulting in low-grade nickel matte and antimony-tin dust.

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