Method for preparing high-quality sodium pyroantimonate by pre-oxidation and metathesis

Abstract

The present application relates to the field of nonferrous metallurgy, and provides a method for preparing high-quality sodium pyroantimonate by pre-oxidation and double decomposition, comprising the following steps: under the assistance of ultrasonic waves, adding antimony oxide and hydrogen peroxide into a dilute nitric acid solution at 50-80 DEG C to react, carrying out liquid-solid separation, washing, and drying to obtain a powdered antimony pentoxide product; slurryzing the antimony pentoxide product with a potassium hydroxide solution, then adding the obtained slurry into a high-pressure reaction kettle, stirring and reacting under high temperature and high pressure, carrying out liquid-solid separation after cooling to obtain a potassium pyroantimonate solution; adding sodium hydroxide into the potassium pyroantimonate solution after heating to 70-90 DEG C, carrying out a double decomposition reaction, carrying out liquid-solid separation, and drying to obtain a sodium pyroantimonate product. The essence of the present application is to achieve the purpose of deeply removing impurities through the two processes of acidic oxidation and pressure dissolution, and to prepare a high-quality sodium pyroantimonate product by using a double decomposition reaction. The present application has the advantages of good quality of the sodium pyroantimonate product, good filtration performance, and stable technical indexes.

Description

[0001] This invention is a divisional application based on the application filed on October 31, 2023, with application number 202311432640.5 and entitled "A method for preparing high-quality sodium pyroantimonate by pre-oxidation metathesis". Technical Field

[0002] This invention relates to heavy metal metallurgical processes in the field of non-ferrous metallurgy, and in particular to a hydrometallurgical method for preparing high-quality sodium pyroantimonate using pre-oxidative metathesis. Background Technology

[0003] Antimony is a brittle, silvery-white metal with poor electrical and thermal conductivity. It is mainly used in alloys, military industry, flame retardants, and glass manufacturing. my country is the world's largest producer of antimony, accounting for over 80% of global production. my country possesses irreplaceable advantages in both antimony resources and production. The main mineral raw materials for antimony smelting include stibnite, antimony-gold ore, and brittle pyrolusite. Antimony flue dust, a byproduct of heavy metal smelting, is an important secondary raw material for antimony recovery.

[0004] The main products of antimony include metallic antimony ingots, antimony white, and sodium pyroantimonate. Sodium pyroantimonate is mainly used as a clarifying and decolorizing agent for industrial glass. Glass products made from it have the advantages of high transparency, no discoloration under light, and low toxicity. It is widely used in television picture tubes, high-grade glass, enamel industry, and semiconductor industry. It accounts for a high proportion of antimony products and is a fine chemical product with broad economic prospects.

[0005] Based on their chemical properties, the raw materials used in the production of sodium pyroantimonate can be divided into two categories: one is high-purity antimony products, represented by industrial pure antimony and industrial antimony white; the other is high-impurity antimony mineral raw materials, represented by stibnite and antimony ash. Existing methods for preparing sodium pyroantimonate mainly include the sodium nitrate oxidation method, the chlorination method, the oxidation reflux method, the potassium salt method, and the air oxidation method. Among these, only the sodium nitrate oxidation method belongs to pyrometallurgical processes, while the others belong to hydrometallurgical processes.

[0006] The sodium nitrate oxidation method is a traditional method for preparing sodium antimonate by oxidizing metallic antimony or antimony trioxide under high-temperature alkaline conditions. First, metallic antimony is mixed with an excess of sodium nitrate and calcined at high temperature in a rotary kiln to oxidize the antimony to its pentavalent state. Finally, the sodium nitrate is washed away with water, and the product is dried and pulverized to produce sodium antimonate pyrophosphate. While the sodium nitrate oxidation method has advantages such as simple process, short flow, and easy operation, it cannot effectively remove impurities during production, and the waste gas generated during production cannot be completely eliminated, resulting in low-quality products. Therefore, it has been phased out.

[0007] The chlorination process involves oxidizing and leaching antimony-containing raw materials with chlorine gas in a hydrochloric acid system. The leachate is then neutralized and hydrolyzed with sodium hydroxide to produce sodium pyroantimonate precipitate. After washing and drying, the sodium pyroantimonate product is obtained. The chlorination process has the advantages of low raw material requirements and good product quality, but it also has disadvantages such as a long process flow, severe equipment corrosion, and large wastewater volume.

[0008] The oxidation reflux method is a one-step process for preparing sodium antimonate by directly oxidizing antimony trioxide with hydrogen peroxide in a sodium hydroxide solution. In this method, antimony trioxide, sodium hydroxide, and water are added to a reactor in a specific ratio. After the slurry is heated to a certain temperature, hydrogen peroxide solution is added dropwise to initiate the oxidation reflux reaction. The reaction product is washed with water and then dried to obtain sodium antimonate. The oxidation reflux method has advantages such as simple process, short flow, and easy operation, but it also has disadvantages such as high Sb(III) content in the product, large hydrogen peroxide consumption, and poor product quality. Current research focuses on solving problems related to raw material adaptability, process impurity removal capabilities, and reducing Sb(III) content.

[0009] The potassium salt method is based on the property that potassium pyroantimonate has high solubility in aqueous solution, while sodium pyroantimonate is almost insoluble in water. First, Sb(III) is oxidized to Sb(V) in a potassium hydroxide system using hydrogen peroxide and dissolved. After liquid-solid separation, the solution reacts with sodium hydroxide to produce the sodium pyroantimonate product. The main advantage of the potassium salt method is the high quality of the sodium pyroantimonate product. The disadvantage is the significant loss of potassium salts in the intermediate products, resulting in excessively high production costs.

[0010] The air oxidation method uses stibnite concentrate or brittle lead-stigmine concentrate as raw material, leaching with sodium sulfide and sodium hydroxide. Antimony is introduced into the solution as sodium thioantimonite. Air is bubbled in to oxidize the sodium thioantimonite to sodium pyroantimonite precipitate. After washing and drying, sodium pyroantimonite product is obtained. The oxidized solution is neutralized, impurity removed, concentrated, and crystallized to recover sodium thiosulfate as a byproduct. The air oxidation method directly produces sodium pyroantimonite from sulfide ore, significantly reducing costs, but it suffers from drawbacks such as a long process flow and poor product quality. Some researchers have proposed using pressure oxidation to shorten the air oxidation time, achieving better results.

[0011] Based on the advantages and disadvantages of the above methods, and addressing the shortcomings of the currently widely used oxidation reflux method, a method for preparing high-quality sodium pyroantimonate products through pre-oxidation metathesis is proposed. Summary of the Invention

[0012] To overcome the shortcomings of the traditional oxidation reflux method, this invention provides a hydrometallurgical method for preparing high-quality sodium pyroantimonate by synergistic pre-oxidation and metathesis, resulting in a product with low moisture content, good filtration performance, and low cost.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows: First, antimony oxide is oxidized and converted in dilute nitric acid solution with hydrogen peroxide. Under ultrasonic assistance, antimony trioxide is oxidized into powdered antimony pentoxide precursor. Second, the powdered antimony pentoxide is dissolved in potassium hydroxide solution under high temperature and pressure to generate potassium pyroantimonate solution. Finally, sodium hydroxide is added to undergo a metathesis reaction to produce high-quality sodium pyroantimonate product. The essence of this invention is to achieve deep impurity removal through two processes: acidic oxidation and pressure dissolution, and to prepare high-quality sodium pyroantimonate product using a metathesis reaction.

[0014] The specific process and parameters are as follows: 1. Acidic oxidative transformation Antimony oxide is oxidized and converted by adding hydrogen peroxide to a dilute nitric acid solution; a dilute nitric acid solution with a mass percentage concentration of 1-10% is prepared and the temperature is raised to 50-80℃, and ultrasonic waves are started and the ultrasonic frequency is controlled at 40-80kHz and the power density at 0.5-1.2W / cm². 2 Antimony oxide and hydrogen peroxide are added simultaneously. The addition rate of antimony oxide is 1.0-50.0 kg / min and the addition rate of hydrogen peroxide is 1.0-25.0 kg / min. After all the hydrogen peroxide has been added, the reaction continues for 10-120 min. Liquid-solid separation is performed by vacuum filtration. The solid is washed and dried to obtain powdered antimony pentoxide product.

[0015] The main chemical reactions that occur during the acidic oxidation transformation process are as follows: PbO + 2HNO3 = Pb(NO3)2 + H2O (1) Sb2O3+2H2O2=Sb2O5↓+2H2O (2) 2. Dissolving under pressure Powdered antimony pentoxide is dissolved under pressure in potassium hydroxide solution to generate potassium pyroantimonate solution; the powdered antimony pentoxide is then slurried with potassium hydroxide solution of concentration 0.5-3.0 mol / L, the slurry is added to a high-pressure reactor and heated to 90-150℃, air is introduced and its partial pressure is maintained at 0.1-1.0 MPa, the reaction is continued to be stirred for 10-120 min and then cooled, the liquid and solid are separated by vacuum filtration, the potassium pyroantimonate solution is sent to the metathesis process, and the insoluble residue is returned to the acidic oxidation conversion process.

[0016] The main chemical reactions that occur during the pressure dissolution process are as follows: Sb2O5+2KOH+5H2O=2KSb(OH)6 (3) 3. Complexity Sodium hydroxide is added to potassium pyroantimonate solution to produce sodium pyroantimonate product; the potassium pyroantimonate solution is heated to 70-90℃, and sodium hydroxide is added at a molar ratio of antimony to sodium hydroxide of 1:1. After the reaction continues for 10-120 minutes, liquid-solid separation is carried out by vacuum filtration. Sodium pyroantimonate is dried and packaged, and the mother liquor is returned to be dissolved under pressure.

[0017] The main chemical reactions that occur during the metathesis process are as follows: KSb(OH)6+NaOH=NaSb(OH)6↓+KOH (4) The nitric acid, hydrogen peroxide, potassium hydroxide, and sodium hydroxide mentioned in this invention are all analytical grade reagents.

[0018] The antimony oxide of this invention contains more than 70.0% antimony by weight.

[0019] Compared with the traditional method for preparing sodium pyroantimonate from antimony oxide, this invention has the following advantages: 1. The preparation of powdered antimony pentoxide precursor by oxidation with hydrogen peroxide in a dilute nitric acid system not only effectively removes lead impurities from the raw materials but also has high oxidation efficiency; 2. The use of pressure dissolution of antimony pentoxide achieves deep removal of impurities, and then a metathesis process is used to prepare high-quality sodium pyroantimonate product, reducing the trivalent antimony content in the sodium pyroantimonate product to less than 0.3%; 3. This invention has the advantages of stable process technical indicators, low reagent consumption, and low production cost. Attached Figure Description

[0020] Figure 1 : Schematic diagram of the process flow of this invention. Detailed Implementation

[0021] Example 1 The antimony content in antimony oxide is 83.30% by weight, the HNO3 content in nitric acid is 65.0% by weight, the H2O2 content in hydrogen peroxide is 28.0% by weight, the NaOH content in sodium hydroxide is 96.5% by weight, and the KOH content in potassium hydroxide is 85% by weight.

[0022] Prepare a 4% (w / w) dilute nitric acid solution and raise the temperature to 80°C. Start the ultrasonic wave and control the ultrasonic frequency at 40 kHz and power density at 0.5 W / cm². 2 Antimony oxide and hydrogen peroxide were added simultaneously. The addition rate of antimony oxide was 30.0 kg / min and the addition rate of hydrogen peroxide was 15.0 kg / min. After all the hydrogen peroxide was added, the reaction continued for 60 min. Liquid-solid separation was carried out by vacuum filtration. The solid was washed and dried to obtain powdered antimony pentoxide product, in which the content of trivalent antimony was 0.07%.

[0023] Powdered antimony pentoxide was slurried in a 2.0 mol / L potassium hydroxide solution. The slurry was added to a high-pressure reactor and heated to 130°C. Air was introduced and the partial pressure was maintained at 0.7 MPa. The reaction was continued with stirring for 60 minutes, followed by cooling. Liquid-solid separation was performed using vacuum filtration. The potassium pyroantimonate solution was sent to the metathesis process, while the insoluble residue was returned to the acidic oxidation conversion process. The potassium pyroantimonate solution was heated to 80°C, and sodium hydroxide was added at a molar ratio of 1:1 (antimony to sodium hydroxide). The reaction was continued for 60 minutes, followed by liquid-solid separation using vacuum filtration. The sodium pyroantimonate was dried and packaged. The sodium pyroantimonate product contained 0.05% trivalent antimony. The mother liquor was returned for pressurized dissolution.

Claims

1. A method for preparing high-quality sodium pyroantimonate through pre-oxidative metathesis, characterized in that, Includes the following steps: (1) Acidic oxidation conversion: Under the assistance of ultrasound, antimony oxide and hydrogen peroxide are added to a dilute nitric acid solution at 50-80℃ to react. After liquid-solid separation, washing and drying, powdered antimony pentoxide product is obtained. (2) Pressure dissolution: The antimony pentoxide product is slurried with potassium hydroxide solution, and then the slurry is added to a high-pressure reactor. The mixture is stirred and reacted under high temperature and high pressure. After cooling, the liquid and solid are separated to obtain potassium pyroantimonate solution. (3) Metathesis: The potassium pyroantimonate solution is heated to 70-90℃ and sodium hydroxide is added to carry out the metathesis reaction. After liquid-solid separation and drying, sodium pyroantimonate product is obtained.

2. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to claim 1, characterized in that, In step (1), the mass percentage concentration of the dilute nitric acid solution is 1-10%.

3. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to claim 1, characterized in that, In step (1), the frequency of the ultrasound is 40-80kHz, and the power density is 0.5-1.2W / cm². 2 .

4. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to claim 1, characterized in that, In step (1), the antimony oxide is added at a rate of 1.0-50.0 kg / min, and the antimony oxide contains more than 70.0% antimony by weight. The hydrogen peroxide is added at a rate of 1.0-25.0 kg / min; The reaction is carried out for 10-120 minutes after all the hydrogen peroxide has been added.

5. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to claim 1, characterized in that, In step (2), the concentration of the potassium hydroxide solution is 0.5-3.0 mol / L.

6. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to claim 1, characterized in that, The temperature inside the high-pressure reactor in step (2) is 90-150℃, and air is introduced and its partial pressure is maintained at 0.1-1.0MPa; The stirring reaction time is 10-120 min.

7. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to claim 1, characterized in that, In step (3), the molar ratio of antimony to sodium hydroxide in the potassium pyroantimonate solution is 1:

1.

8. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to claim 1, characterized in that, The reaction time for the metathesis reaction is 10-120 min.

9. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to claim 1, characterized in that, The insoluble residue obtained after liquid-solid separation in step (2) is returned to the acidic oxidation conversion process; The mother liquor obtained after liquid-solid separation in step (3) is returned to the pressurized dissolution process.

10. The method for preparing high-quality sodium pyroantimonate via pre-oxidative metathesis according to any one of claims 1-9, characterized in that, The liquid-solid separation described in steps (1)-(3) all employs vacuum filtration.

Images