Production method of cadmium sulfide

Abstract

The invention discloses a production method of cadmium sulfide, which comprises the following steps: by taking acidic waste liquid in the non-ferrous metal metallurgy industry as a raw material and magnesium oxide as a treating agent, finely controlling the pH value of the liquid, separating out Cd, Bi and Sb elements in the liquid, filtering the liquid to obtain a cadmium sulfide crude product, removing Mg, Bi and Sb elements by acid pickling, and then cleaning and drying to obtain a cadmium sulfide product. On one hand, the production cost of cadmium sulfide products is reduced, the economic benefits of smelting enterprises are improved, and resource recycling is achieved. On the other hand, Cd, Bi and Sb elements in the waste liquid can be effectively recycled, the number of hazardous wastes is further reduced, and the arsenic-containing waste water pollution treatment difficulty is lowered.

Description

Technical Field

[0001] The invention belongs to the field of inorganic fine chemicals and relates to a production method of cadmium sulfide. Background Art

[0002] As an inorganic pigment, cadmium sulfide (CdS) is mainly used for coloring paints, enamels, glass, and plastics, and is widely used in industrial production of paints, plastics, etc. On the other hand, since CdS nanofilms have good photoelectric conversion properties, can better match the visible light region of the solar spectrum and have very good transmittance to visible light, CdS nanofilms are usually used as window layers together with P-type semiconductor materials to form heterojunction solar cells. Therefore, cadmium sulfide will be the main research direction for the development of cheap and high-efficiency solar cells in the future.

[0003] At present, the production method of cadmium sulfide is generally to precipitate from aqueous solution or to directly melt and synthesize the component single substances. There are generally defects such as difficult to control reaction conditions and high preparation cost.

[0004] A Chinese patent application with publication number CN106745198A discloses a method for preparing cadmium sulfide, which comprises introducing an inert gas into a sulfur evaporation chamber, a reaction chamber, and a cadmium evaporation chamber in advance, adding sulfur and cadmium into the sulfur evaporation chamber and the cadmium evaporation chamber, respectively, first raising the temperature of the reaction chamber to 1100-1200°C, and then simultaneously raising the temperature of the sulfur evaporation chamber and the cadmium evaporation chamber to 750-850°C and 250-300°C. When all three reach the above temperatures, the blowing direction of the inert gas in the sulfur evaporation chamber is directed toward the reaction chamber, and the flow rate thereof is adjusted to 600-700 ml / min; the blowing direction of the inert gas in the cadmium evaporation chamber is directed toward the reaction chamber, and the flow rate thereof is adjusted to 250-350 ml / min, and the above flow rate and temperature are maintained for a reaction of 6-8 hours; after the reaction of 6-8 hours, the heating is stopped, the inert gas is continuously added, and the reaction chamber is cooled to room temperature to obtain the synthetic product cadmium sulfide. Although it can improve the purity of the synthesized cadmium sulfide to a certain extent, it still belongs to the technical route of synthesizing using single components, and has the defects of difficult control of reaction conditions and high preparation cost.

[0005] The non-ferrous metal smelting industry uses the pyrometallurgical smelting-gas acid production system to roast or smelt metal ore powder. The smelting flue gas is sprayed and washed with dilute sulfuric acid to form an acidic liquid during the production of sulfuric acid. The acidity of the liquid is about 3-6%, and the main components are: As about 18000 mg / L, Cd about 1500 mg / L, Bi about 40 mg / L, Sb about 30 mg / L, Cu about 20 mg / L, Fe about 60 mg / L, Pb about 50 mg / L, Zn about 30 mg / L.

[0006] The Chinese authorized invention patent with announcement number CN106495215B discloses "a method for producing magnesium arsenate from arsenic-containing wastewater", which uses arsenic-containing wastewater from non-ferrous metal smelting enterprises to produce magnesium arsenate. This technology recovers Fe, Zn, Cu and other elements through processes such as neutralizing liquid, removing Fe, Zn and Cu from wastewater, but does not involve the treatment of Cd, Bi, Sb and other elements, which not only causes a waste of resources, but also makes it difficult to solve the problem of arsenic-containing wastewater pollution. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for producing cadmium sulfide, and to produce cadmium sulfide products by recovering cadmium elements from acidic waste liquid in the non-ferrous metal smelting industry; another technical problem to be solved by the present invention is to realize the recovery of Bi and Sb elements in acidic waste liquid in the non-ferrous metal smelting industry, and further eliminate the potential pollution hazards.

[0008] The technical solution of the present invention is as follows: A method for producing cadmium sulfide, comprising the steps of: Step 1), add the arsenic-containing waste liquid into a reaction vessel A with a heating and stirring mechanism, and heat the material in the reaction vessel A to 40-60°C (Note: if the temperature is too low, magnesium oxide will not react easily, and if the temperature is too high, the reaction will be too intense, making it difficult to control the reaction result), start stirring the reaction vessel A, and then add magnesium oxide powder into the reaction vessel A, and continue stirring for 20-30 minutes; in this step, the pH value is controlled to between 1 and 2; Step 2), filtering the material in reaction vessel A, and pumping the filtrate into reaction vessel B with a stirring mechanism; Step 3), start stirring the reaction vessel B and add magnesium hydroxide slurry, add flocculant after 10 to 20 minutes, and continue stirring for 3 to 5 minutes (Note: if the stirring time is too long, the flocculation effect will decrease); in this step, the pH value is controlled between 6 and 6.5; Step 4), the material in the reaction vessel B is filtered, and the filter residue is crude cadmium sulfide.

[0009] Furthermore, the production method of cadmium sulfide further comprises the following steps: Step 5), add dilute sulfuric acid to the crude cadmium sulfide to prepare a cadmium sulfide slurry; stir to make the impurities including Mg, Bi and Sb fully react with sulfuric acid to form corresponding sulfates dissolved in the liquid; filter the liquid to obtain a cadmium sulfide filter residue; add water to the cadmium sulfide filter residue to wash away the impurities attached to the surface of the cadmium sulfide, filter the liquid, and dry the filter residue to obtain a pure cadmium sulfide product.

[0010] Furthermore, in step 5), the filtrate is collected while filtering the liquid to obtain the cadmium sulfide filter residue; the filtrate is collected while filtering the liquid after washing with water; zinc is added to the collected filtrate to displace the Bi and Sb elements, and the Bi and Sb elements are recovered; the liquid after the replacement is used to extract and recover elements including zinc, lead, iron, arsenic and magnesium.

[0011] Furthermore, the method for determining the amount of magnesium oxide powder added in step 1) is: detecting the acidity of the arsenic-containing waste liquid, calculating the theoretical amount of magnesium oxide according to the equation for the reaction of sulfuric acid and magnesium oxide to produce magnesium sulfate and water, and adding 1.1 to 1.15 times the theoretical amount.

[0012] Furthermore, in step 1), the method for controlling the pH value of the waste liquid is: adding magnesium oxide powder in batches, testing the pH value of the liquid at intervals, and controlling the pH value at 1-2.

[0013] Furthermore, the magnesium hydroxide slurry used in step 3) is prepared by mixing and stirring magnesium oxide and water; wherein the mass ratio of magnesium oxide to water is 1:(2-3).

[0014] Furthermore, the method for determining the amount of magnesium hydroxide slurry added in step 3) is: adding magnesium hydroxide slurry in batches, testing the pH value of the liquid at intervals, and stopping the addition when the pH value is controlled at 6 to 6.5.

[0015] Furthermore, in step 3), the ratio between the volume of the arsenic-containing waste liquid and the volume of the added flocculant is 1m³: (200-500ml); the flocculant is polyacrylamide.

[0016] Furthermore, the filtrate obtained by filtering in step 4) is used to extract and recover elements including zinc, lead, iron, arsenic and magnesium.

[0017] Furthermore, the arsenic-containing waste liquid refers to the arsenic-containing waste liquid produced during the production of sulfuric acid using a pyrometallurgical-flue gas acid production system.

[0018] The present invention uses acid waste liquid from the non-ferrous metal smelting industry as raw material, magnesium oxide as a treatment agent, and finely controls the pH value of the liquid to precipitate Cd, Bi, and Sb elements in the liquid, filters the liquid to obtain a crude cadmium sulfide product, removes Mg, Bi, and Sb elements by pickling, and then obtains a cadmium sulfide product after washing, drying, and crushing. Compared with the prior art, the present invention has the following beneficial effects.

[0019] 1. The present invention recovers cadmium elements from acidic waste liquid in the non-ferrous metal smelting industry and produces cadmium sulfide products, which, on the one hand, reduces the production cost of cadmium sulfide products, improves the economic benefits of smelting enterprises, and realizes resource recycling. On the other hand, it can effectively recover Cd, Bi, and Sb elements in the waste liquid, further reduce the amount of hazardous waste, and reduce the difficulty of treating arsenic-containing wastewater pollution.

[0020] 2. After purification treatment, the cadmium sulfide product prepared by the present invention has a higher purity and can better meet market demand. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with examples and experimental data.

[0022] The following is a crude cadmium sulfide preparation example of the present invention:

[0023] Raw materials: 1m³ of arsenic-containing waste liquid produced during the production of sulfuric acid in a copper smelting enterprise's "pyrometallurgical smelting-flue gas acid production system". According to the measurement, the acidity of the waste liquid is 6%, the As content is 18000mg / L, the Cd content is 1500mg / L, the Bi content is 40mg / L, the Sb content is 26mg / L, the Cu content is 17mg / L, the Fe content is 55mg / L, the Pb content is 50mg / L, and the Zn content is 31 mg / L.

[0024] The first step is to pour 10 kg of magnesium oxide with a content of 80% (mass ratio, the same below) into a stirring tank, add 20 kg of clean water, and stir continuously to prepare magnesium hydroxide slurry.

[0025] The second step is to add 1m³ of the arsenic-containing waste liquid into reaction tank A, heat the material in reaction tank A to 50°C, start the stirring paddle of reaction tank A, and then add 50kg of magnesium oxide powder into reaction tank A three times, continue stirring for 20 minutes, measure the liquid pH value = 2.0, and stop stirring.

[0026] Step 3: Pump the material in reaction tank A into the filter for filtration, and then pump the filtrate into reaction tank B; collect the filter residue for centralized treatment. Centralized treatment plan for filter residue: The main components of the filter residue are silicon dioxide and magnesium oxide that has not reacted completely. These two substances are auxiliary materials in the copper smelting process, which are used for slag making and increasing the fluidity of the melt. They can be directly added to the copper coarse ore powder for production batching.

[0027] Step 4: Start the stirring paddle of reaction tank B to make the liquid in the tank flow quickly, add 15 kg of magnesium hydroxide slurry prepared in the first step in batches, measure the liquid pH value = 6.0, the liquid is beige, add 200 ml of polyacrylamide as a flocculant after 10 to 20 minutes of stirring, continue stirring for 3 minutes and then stop. 2 Flocculation precipitation.

[0028] Step 5: Pump the material in the reaction tank B into the filter for filtration, and the filter residue is 6.5 kg of crude cadmium sulfide. After the elements such as zinc, lead, iron, arsenic and magnesium are extracted from the filtrate, it is reused in the dilute acid spraying flue gas process.

[0029] The following is a crude cadmium sulfide purification embodiment of the present invention:

[0030] Step 6: Put 6.5 kg of crude cadmium sulfide into heating reaction tank C, add 10 kg of 5% dilute sulfuric acid, turn on the heater, and start stirring after the liquid temperature rises to 60°C to fully mix the liquid and the crude cadmium sulfide, so that the Mg, Bi, and Sb elements react into corresponding sulfates and dissolve in the liquid.

[0031] Step 7: Pump the liquid in the reaction tank C into the filter for filtration to obtain 3.8 kg of cadmium sulfide residue. Add zinc wire to the filtrate to displace Bi and Sb, and recover Bi and Sb. The main components of the liquid after the replacement are magnesium sulfate and zinc sulfate, which are mixed with the filtrate obtained in the fifth step to extract zinc, lead, iron, arsenic, magnesium and other elements.

[0032] Step 8: Put 3.8 kg of cadmium sulfide filter residue into reaction tank D, add 10 kg of clean water, start stirring to fully mix the solid and liquid, and wash away impurities attached to the surface of cadmium sulfide.

[0033] Step 9. Pump the liquid in the reaction tank D into a filter for filtration to obtain 3.7 kg of pure cadmium sulfide; add zinc wire to the filtrate to displace Bi and Sb, and recover Bi and Sb. The main components of the liquid after the replacement are magnesium sulfate and zinc sulfate, which are mixed with the filtrate obtained in the fifth step to extract elements such as zinc, lead, iron, arsenic, and magnesium.

[0034] Step 10: Put 3.7 kg of pure cadmium sulfide filter residue into a drying box, turn on the drying box, set the temperature to 230°C, take it out after 10 hours and weigh 1.91 kg. The cadmium sulfide content is 98.5% detected by fluorescence spectroscopy.

Claims

1. A method for producing cadmium sulfide, characterized in that Follow these steps to produce: Step 1), add the arsenic-containing waste liquid into a reaction vessel A with a heating and stirring mechanism, heat the material in the reaction vessel A to 40-60°C, start stirring the reaction vessel A, then add magnesium oxide powder into the reaction vessel A, and continue stirring for 20-30 minutes; in this step, the pH value is controlled to between 1 and 2; Step 2), filtering the material in reaction vessel A, and pumping the filtrate into reaction vessel B with a stirring mechanism; Step 3), start stirring in reaction vessel B and add magnesium hydroxide slurry, add flocculant after 10 to 20 minutes, and continue stirring for 3 to 5 minutes; in this step, the pH value is controlled between 6 and 6.5; Step 4), the material in the reaction vessel B is filtered, and the filter residue is crude cadmium sulfide.

2. The method for producing cadmium sulfide according to claim 1, characterized in that The following steps are also included: Step 5), add dilute sulfuric acid to the crude cadmium sulfide to prepare a cadmium sulfide slurry; stir to make the impurities including Mg, Bi and Sb fully react with sulfuric acid to form corresponding sulfates dissolved in the liquid; filter the liquid to obtain a cadmium sulfide filter residue; add water to the cadmium sulfide filter residue to wash away the impurities attached to the surface of the cadmium sulfide, filter the liquid, and dry the filter residue to obtain a pure cadmium sulfide product.

3. The method for producing cadmium sulfide according to claim 2, wherein: In step 5), the liquid is filtered to obtain the cadmium sulfide filter residue and the filtrate is collected; after washing with water, the liquid is filtered and the filtrate is collected; zinc is added to the collected filtrate to displace the Bi and Sb elements, and the Bi and Sb elements are recovered; the liquid after the replacement is used to extract and recover elements including zinc, lead, iron, arsenic and magnesium.

4. The method for producing cadmium sulfide according to claim 1, characterized in that The method for determining the amount of magnesium oxide powder added in step 1) is: detecting the acidity of the arsenic-containing waste liquid, calculating the theoretical amount of magnesium oxide according to the equation for the reaction of sulfuric acid and magnesium oxide to produce magnesium sulfate and water, and adding 1.1 to 1.15 times the theoretical amount.

5. The method for producing cadmium sulfide according to claim 1, characterized in that: The method for controlling the pH value of the waste liquid in step 1) is: adding magnesium oxide powder in batches, testing the pH value of the liquid at intervals, and controlling the pH value at 1-2.

6. The method for producing cadmium sulfide according to claim 1, characterized in that: The magnesium hydroxide slurry used in step 3) is prepared by mixing and stirring magnesium oxide and water; wherein the mass ratio of magnesium oxide to water is 1:(2-3).

7. The method for producing cadmium sulfide according to claim 1, characterized in that The method for determining the amount of magnesium hydroxide slurry added in step 3) is: adding magnesium hydroxide slurry in batches, testing the pH value of the liquid at intervals, and stopping the addition when the pH value is controlled at 6 to 6.

5.

8. The method for producing cadmium sulfide according to claim 1, characterized in that: In step 3), the ratio between the volume of the arsenic-containing waste liquid and the volume of the added flocculant is 1m³: (200-500ml); the flocculant is polyacrylamide.

9. The method for producing cadmium sulfide according to claim 1, characterized in that: Step 4) The filtrate obtained by filtration is used to extract and recover elements including zinc, lead, iron, arsenic and magnesium.

10. The method for producing cadmium sulfide according to any one of claims 1 to 9, characterized in that: The arsenic-containing waste liquid refers to the arsenic-containing waste liquid produced during the production of sulfuric acid using a pyrometallurgical-flue gas acid production system.