Method for low-temperature and rapid removal of copper by sodium antimonate

Abstract

The application discloses a method for removing copper from sodium antimonate at low temperature and at high speed, and the method comprises the following steps: under the conditions of negative pressure, microwave heating and stirring, removing copper from sodium antimonate, a water solvent and a composite copper removal reagent; after the reaction is completed, solid-liquid separation is performed; the obtained liquid part is a reaction mother liquor, and the obtained solid part is copper-removed sodium antimonate; and the copper removal substance in the composite copper removal reagent is an ammonium source substance. The method has the advantages of low reaction temperature, short reaction time, fast reaction speed, energy saving and environmental protection, good copper removal effect, high product yield, and the like. The obtained sodium antimonate product can meet the requirements of various glass fining agents and decoloring agents; the method reduces the requirement for copper in raw materials in the preparation of sodium antimonate, expands the source of the sodium antimonate raw material, reduces the cost of the raw material, and thus reduces the production cost of the sodium antimonate product.

Description

Technical Field

[0001] This invention relates to a method for purifying sodium antimonate, specifically a method for removing copper from sodium antimonate. Background Technology

[0002] Sodium antimonate, also known as sodium pyroantimonate, is a white crystalline powder when it is in good condition. It is sparingly soluble in water and is mainly used as a clarifying and decolorizing agent in cathode ray tube glass, optical glass, photovoltaic glass, and various other high-grade glass products. Sodium antimonate products containing excessive copper will appear pale blue under sunlight (Cu...). + Black, Cu 2+ Copper (blue) is used in glass manufacturing and affects the glass's color; therefore, it is a major harmful impurity and its control is extremely strict. The Chinese non-ferrous metals standard specifies Cu ≤ 0.005%. Current sodium antimonate preparation technology mainly uses grade 0 or higher antimony trioxide and high-quality NaOH as raw materials, undergoing an oxidation reaction at high temperatures. Due to the consistently high price of grade 0 or higher antimony trioxide, the cost of sodium antimonate products using this as a raw material has been significantly increased. Antimony trioxide (residual antimony oxide powder) obtained from antimony white furnace smelting (Cu: 0.3%–0.5%) has a high copper content and relatively low price. Using this as a raw material for sodium antimonate could reduce the cost of sodium antimonate products. However, because this residual antimony oxide powder has an excessive Cu content, it easily produces substandard sodium antimonate products with excessive Cu content.

[0003] Currently, manufacturers handle this by: (1) directly returning sodium antimonate with excessive copper content to the antimony smelting system; and (2) adding small amounts of sodium antimonate with less excessive copper content to qualified products for sale. Method (1) causes copper to return to the antimony smelting system, creating a vicious cycle; and method (2) makes it easy for high-Cu sodium antimonate products to accumulate in large quantities or be sold at low prices. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for removing copper from sodium antimonate at low temperature and quickly, which can convert sodium antimonate with excessive copper content into qualified products.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: A method for low-temperature and rapid copper removal using sodium antimonate, comprising sodium antimonate containing excessive copper, an aqueous solvent, and a composite copper removal reagent, wherein a copper removal reaction is carried out under negative pressure, microwave heating, and stirring conditions; after the reaction is completed, solid-liquid separation is performed, the resulting liquid portion is the reaction mother liquor, and the resulting solid portion is the copper-removing sodium antimonate; the copper-removing substance in the composite copper removal reagent is an ammonium source substance. The ammonium source substance contains ammonium or can be hydrolyzed in water to generate ammonium ions.

[0006] To avoid negatively impacting product purity, water-based solvents should ideally not introduce impurities that are difficult to remove, such as deionized water.

[0007] This invention features low reaction temperature, short reaction time, fast reaction rate, energy saving and environmental protection, excellent copper removal effect, and removes over 95% of the copper in sodium antimonate as Cu(NH3)4. 2+ The complexed ions enter the mother liquor, resulting in excellent copper removal and high product yield.

[0008] Preferably, the pressure during the copper removal reaction is -0.001 to -0.006 MPa, more preferably -0.001 to -0.004 MPa.

[0009] By adopting the above technical solution, a better copper removal effect can be achieved.

[0010] Preferably, the microwave heating during the copper removal reaction results in a reaction temperature of 30–80°C, and more preferably, a temperature of 30–60°C.

[0011] By adopting the above technical solution, a better copper removal effect can be achieved.

[0012] Preferably, the copper removal reaction time is 40-120 min, more preferably 40-90 min.

[0013] By adopting the above technical solution, a better copper removal effect can be achieved.

[0014] Preferably, the ammonium source material includes urea and ammonia: the ratio of urea to ammonia is 2.5 to 5:1, more preferably 2.5 to 4:1, calculated based on the total free ammonium obtained after hydrolysis of each.

[0015] Both urea and ammonia can be commercially available industrial products, such as commercially available industrial-grade urea containing 46% nitrogen and commercially available industrial-grade ammonia containing 25% to 28% ammonia. Both can be used directly to prepare composite copper removal reagents.

[0016] Preferably, the Cu content in the composite copper removal reagent is <5 mg / L.

[0017] By adopting the above technical solution, a better copper removal effect can be achieved.

[0018] Preferably, the amount of the composite copper removal reagent is such that the total free ammonium in the reaction system that can participate in the reaction is 2.5 to 8 times the amount required for the complete reaction of copper (i.e., the excess coefficient is 2.5 to 8), more preferably 3 to 6 times (i.e., the excess coefficient is 3 to 6).

[0019] By adopting the above technical solution, a better copper removal effect can be achieved.

[0020] Preferably, the mass ratio of the aqueous solvent to the sodium antimonate containing excessive copper is 4-8:1 (i.e., liquid / solid = 4-8:1); more preferably, it is 4-6:1 (i.e., liquid / solid = 4-6:1).

[0021] By adopting the above technical solution, a better copper removal effect can be achieved.

[0022] Preferably, the sodium antimonate containing excessive copper contains more than 0.005 wt% copper; more preferably, it contains 0.047 wt% to 0.32 wt% copper.

[0023] The standard requires sodium antimonate with a Cu content of ≤0.005%. The method of this invention is designed based on the treatment of sodium antimonate containing more than 0.005 wt% copper, which has a good copper removal effect within this range; and the treatment efficiency is even higher within a more preferred copper content range.

[0024] Preferably, when the Cu content in the reaction mother liquor is <5 mg / L, it can be recycled as a composite copper removal reagent or water solvent for the next reaction.

[0025] By adopting the above technical solution, the mother liquor can be recycled, resources can be saved and emissions reduced, while achieving better copper removal effect.

[0026] Preferably, when the Cu content in the mother liquor is ≥5 mg / L, copper precipitation is performed using the TMT chelation precipitation method.

[0027] The composite copper removal process typically involves circulating the reaction mother liquor 3-8 times before performing a copper precipitation treatment. The process can then be repeated after this treatment.

[0028] Preferably, the sodium antimonate is washed once or more with a washing mother liquor to obtain the sodium antimonate product.

[0029] The above technical solution can achieve better washing results. The resulting product is a qualified product with a copper content of ≤0.005%.

[0030] Preferably, the washing mother liquor is a dilute solution of urea with a urea content of 0.8 wt% to 1.5 wt% and a Cu content of <5 mg / L; more preferably, the urea content is 1 wt% to 1.2 wt%.

[0031] By adopting the above technical solution, a better washing effect can be achieved.

[0032] Preferably, when the Cu content of the mother liquor after washing is <5 mg / L, it can be recycled as the mother liquor for the next washing cycle.

[0033] By adopting the above technical solution, the mother liquor can be recycled, resources can be saved and emissions reduced, while achieving better copper removal effect.

[0034] Preferably, when the Cu content of the mother liquor after washing is ≥5mg / L, copper deposition is performed using the TMT chelation precipitation method.

[0035] The washing mother liquor is generally recycled 8 to 12 times before undergoing a copper plating treatment. After the treatment, it can be recycled again.

[0036] Sodium antimonate, also known as sodium pyroantimonate, is a white crystalline powder when it is in good condition. It is difficult to dissolve in water, and products with excessive copper content will appear pale blue in sunlight.

[0037] Urea, also known as urea or carbamide, has the chemical formula CH4N2O or CO(NH2)2. It is one of the simplest organic compounds composed of carbon, nitrogen, oxygen, and hydrogen. It is a white crystalline granule that is extremely soluble in water. When dissolved in water, it undergoes the following reaction:

[0038] CO(NH2)2 + 2H2O = (NH4)2CO3

[0039] The generated (NH4)2CO3 undergoes a decomposition reaction upon heating:

[0040] (NH4)2CO3→2NH4 + +CO3 2-

[0041] Industrial ammonia water is an aqueous solution containing ammonia, with NH3·H2O as its main component. It is colorless, transparent, has a pungent odor, and is highly volatile. The following chemical equilibrium exists in dilute solutions of ammonia water:

[0042] NH3·H2O ←→ NH4 + +OH -

[0043] Urea is chemically more stable in air than ammonia, has less irritating odor, and the ammonium ions released during the reaction have similar activity to those in ammonia. It is also easier to store and transport. However, urea is more expensive than ammonia. To reduce the cost of copper removal, urea is chosen as the main ammonium source for copper removal, with ammonia as the secondary ammonium source.

[0044] The copper removal reagent composed of urea and ammonia utilizes the Cu in sodium antimonate. 2+ It readily reacts with NH4 in ammonium-containing solutions. + A stable [Cu(NH3)4] is formed. 2+ The complex ion is removed from sodium antimonate and enters the mother liquor. The ionic equation for the reaction is as follows:

[0045] Cu 2+ +NH4 + →[Cu(NH3)4] 2+

[0046] During copper removal operations, ammonia gas released by heating is absorbed by maintaining a negative pressure environment and then recovered (e.g., by using magnesium ammonium phosphate precipitation to remove NH4). + The process generates MgNH4PO4·6H2O, thus avoiding the impact of the released ammonia gas on the operation and the surrounding environment.

[0047] Ammonia gas released during the reaction due to heat is absorbed by a jet pump. The ammonium-containing jet circulating liquid is periodically precipitated with magnesium ammonium phosphate to remove over 90% of the NH4+. + MgNH4PO4·6H2O is generated and separated from the bottom of the circulation tank by filtration.

[0048] TMT is an environmentally friendly organic copper plating agent, commonly available in a 15% aqueous solution, often referred to as TMT-15. It exhibits good copper removal efficiency and a high copper plating rate under weakly alkaline conditions. The principle behind its copper plating process is as follows:

[0049] 3[Cu(NH3)4] 2+ +2[TMT] 3+ =Cu3(TMT) 2(S) +12NH3(g)

[0050] Beneficial effects of the present invention

[0051] (1) This invention features low reaction temperature, short reaction time, fast reaction speed, energy saving and environmental protection, excellent copper removal effect, and removes more than 95% of the copper in sodium antimonate as Cu(NH3)4. 2+ The complexed ions enter the mother liquor, which has a good copper removal effect and a high product yield;

[0052] (2) The obtained sodium antimonate product can meet the needs of various glass clarifying agents and decolorizing agents;

[0053] (3) It reduces the copper requirements in the raw materials for sodium antimonate preparation, expands the sources of sodium antimonate raw materials, reduces the cost of raw materials, and thus reduces the production cost of sodium antimonate products.

[0054] (4) It provides a technical route for the open-circuit removal of copper from antimony residue in pyrometallurgical antimony trioxide. Detailed Implementation

[0055] All raw materials used in the embodiments of this invention were purchased through conventional commercial channels.

[0056] Example 1

[0057] Add 2200L of deionized water to a microwave reactor equipped with a stirring device and a vacuum jetting device, and turn on the stirring and jetting pumps. Weigh the raw materials according to a liquid / solid ratio of 5 and a free total ammonium excess coefficient of 4: add 440kg of sodium antimonate containing 0.073wt% copper, 1.0kg of urea, and 2.1kg of ammonia water; maintain a negative pressure of 0.004MPa, microwave heat to 40℃, and react for 80min.

[0058] After the reaction is complete, the mixture is centrifuged and filtered. The mother liquor can be returned to the reactor and replenished with deionized water and free total ammonium for the next reaction. The filter cake is washed twice with 60 kg of deionized water containing 1.2 wt% urea, and dried to obtain the product. The washing mother liquor is pumped to the washing liquid storage tank for the next product washing.

[0059] In this embodiment, 435.6 kg of product was obtained, with a yield of 99%. The product is a white (whiteness ≥92%) crystalline powder. The product was tested and found to contain 0.0032% copper, with a Cu removal rate of 95.67%.

[0060] Example 2

[0061] Add 2150L of the mother liquor from Example 1 to a microwave reactor equipped with a stirring device and a vacuum jetting device, and add 50L of deionized water. Detect the concentration of free total ammonium in the mother liquor, and turn on the stirring and jetting pumps. Weigh the raw materials according to a liquid / solid ratio of 5.5 and a free total ammonium excess coefficient of 4.5 (including the free total ammonium in the mother liquor from Example 1). Add 400kg of sodium antimonate containing 0.047% copper. Calculate the free total ammonium obtained after the hydrolysis of urea and ammonia, and add urea and ammonia at a ratio of 2.5:1. Maintain a negative pressure of 0.002MPa, microwave heat to 50°C, and react for 70 minutes.

[0062] After the reaction is complete, the mixture is centrifuged and filtered. The mother liquor can be returned to the reactor and replenished with deionized water and free total ammonium for the next reaction. The filter cake is washed twice with 60 kg of washing mother liquor containing 1.2 wt% urea, and dried to obtain the product. The washing mother liquor is pumped to the washing liquid storage tank for the next product washing.

[0063] In this embodiment, 395.2 kg of product was obtained, with a yield of 98.8%. The product was white (whiteness ≥92%) crystalline powder. The product was tested and found to contain 0.0022% copper, with a Cu removal rate of 95.3%.

[0064] Example 3

[0065] Add 2150L of the mother liquor from Example 2 to a microwave reactor equipped with a stirring device and a vacuum jetting device, and add 50L of deionized water. Detect the concentration of free total ammonium in the mother liquor. Turn on the stirring and jetting pump. Weigh the raw materials according to a liquid / solid ratio of 5.5 and a free total ammonium excess coefficient of 6.0 (including the free total ammonium in the mother liquor from Example 2). Add 400kg of sodium antimonate containing 0.096% copper. Calculate the free total ammonium obtained after hydrolysis of urea and ammonia, and add urea and ammonia in a 5:1 ratio. Maintain a negative pressure of 0.001MPa, microwave heat to 45°C, and react for 70 minutes.

[0066] After the reaction is complete, the mixture is centrifuged and filtered. The mother liquor can be returned to the reactor and replenished with deionized water and free total ammonium for the next reaction. The filter cake is washed twice with 60 kg of washing mother liquor containing 1.2 wt% urea, and dried to obtain the product. The washing mother liquor is pumped to the washing liquid storage tank for the next product washing.

[0067] In this embodiment, 396.4 kg of product was obtained, with a yield of 99.1%. The product is a white (whiteness ≥92%) crystalline powder. The product was tested and found to contain 0.0035% copper, with a Cu removal rate of 96.4%.

[0068] Example 4

[0069] Add 2150L of the mother liquor from Example 3 to a microwave reactor equipped with a stirring device and a vacuum jetting device, and add 50L of deionized water. Detect the concentration of free total ammonium in the liquid. Turn on the stirring and jetting pump. Weigh the raw materials according to a liquid / solid ratio of 5.8 and a free total ammonium excess coefficient of 5.5 (including the free total ammonium in the mother liquor from Example 3). Add 380kg of sodium antimonate containing 0.19% copper. Calculate the free total ammonium obtained after hydrolysis of urea and ammonia, and add urea and ammonia at a ratio of 3.5:1. Maintain a negative pressure of 0.004MPa, microwave heat to 55°C, and react for 80 minutes.

[0070] After the reaction is complete, the mixture is centrifuged and filtered. The mother liquor can be returned to the reactor and replenished with deionized water and free total ammonium for the next reaction. The filter cake is washed twice with 60 kg of washing mother liquor containing 1.2 wt% urea, and dried to obtain the product. The washing mother liquor is pumped to the washing liquid storage tank for the next product washing.

[0071] In this embodiment, 377.8 kg of product was obtained, with a yield of 99.4%. The product was white (whiteness ≥92%) crystalline powder. The product was tested and found to contain 0.0039% copper, with a Cu removal rate of 97.9%.

[0072] Example 5

[0073] Add 2150L of the mother liquor from Example 4 to a microwave reactor equipped with a stirring device and a vacuum jetting device, and add 50L of deionized water. Detect the concentration of free total ammonium in the mother liquor. Turn on the stirring and jetting pump. Weigh the raw materials according to liquid / solid ratio = 6 and free total ammonium excess coefficient 6 (including the free total ammonium in the mother liquor from Example 4): add 367kg of sodium antimonate containing 0.32% copper. Calculate the free total ammonium obtained after hydrolysis of urea and ammonia, and add urea and ammonia in a 4:1 ratio. Maintain a negative pressure of 0.003MPa, microwave heat to 60°C, and react for 90min.

[0074] After the reaction is complete, the mixture is centrifuged and filtered. The mother liquor can be returned to the reactor and replenished with deionized water and free total ammonium for the next reaction. The filter cake is washed twice with 60 kg of washing mother liquor containing 1.2% urea, and dried to obtain the product. The washing mother liquor is pumped to the washing liquid storage tank for the next product washing.

[0075] In this embodiment, 364.2 kg of product was obtained, with a yield of 99.2%. The product was white (whiteness ≥92%) crystalline powder. The product was tested and found to contain 0.0041% copper, with a Cu removal rate of 98.2%.

[0076] Reference Example

[0077] When the Cu content of the mother liquor or washing solution is ≥5mg / L, its recycling should be stopped, and it should be stored in a concentrated manner until a certain amount is reached before copper plating treatment. The treatment method can refer to the following:

[0078] 2150 L of the reaction mother liquor, after seven cycles, was added to a microwave reactor equipped with a stirring device and a vacuum jetting device. Analysis of the mother liquor showed Cu = 5.12 mg / L and free total ammonium concentration of 13.3 mg / L. The pH was adjusted to 9–10, and TMT-15 was added according to the chemical reaction molar ratio (TMT to Cu molar ratio of 2:3). The stirring and jetting pump were turned on, and microwave heating was initiated at 35°C. Heating was then stopped, and stirring was stopped after 30 minutes. The mixture was filtered, and the Cu in the filtrate was 0.12 mg / L. The filter residue was reddish-brown Cu3(C3N3S3)2·1.5H2O, indicating a copper removal rate of 97.7%.

[0079] The treated mother liquor or washing liquid can be recycled and reused.

Claims

1. A method for low-temperature, rapid removal of copper by sodium antimonate, characterized in that, The copper-excessive sodium antimonate, water solvent and composite copper removal reagent are subjected to copper removal reaction under the conditions of negative pressure, microwave heating and stirring; after the reaction, solid-liquid separation is performed, and the obtained liquid part is a reaction mother liquor, and the obtained solid part is copper-removed sodium antimonate; the copper removal substance in the composite copper removal reagent is an ammonium source substance; The microwave heating in the copper removal reaction makes the reaction temperature be 30-80 ℃; The ammonium source substance is urea and ammonia water.

2. The process for low temperature, rapid decopperization of sodium antimonate according to claim 1, characterized in that, The pressure in the copper removal reaction is-0.001 to-0.006 MPa; and the time of the copper removal reaction is 40-120 min.

3. The process for low temperature, rapid de-coppering of sodium antimonate according to claim 1 or 2, characterized in that, The mass ratio of urea to ammonia water, calculated according to the total free ammonium obtained after hydrolysis of urea and ammonia water, is 2.5-5:1; the ammonia water is industrial-grade ammonia water containing 25%-28% ammonia; and the Cu content in the composite copper removal reagent is less than 5 mg / L.

4. The process for low temperature, rapid de-coppering of sodium antimonate according to claim 3, characterized in that, The amount of the composite copper removal reagent is such that the free total ammonium available for reaction in the reaction system is 2.5-8 times the amount required for complete reaction of copper elements.

5. The process for low temperature, rapid de-coppering of sodium antimonate according to claim 1 or 2, characterized in that, The mass ratio of the water solvent to the copper-excessive sodium antimonate is 4-8:1; and the copper-excessive sodium antimonate contains copper of 0.005 wt% or more.

6. The process for low temperature, rapid decopperization of sodium antimonate according to claim 4, characterized in that, The mass ratio of the water solvent to the copper-excessive sodium antimonate is 4-8:1; and the copper-excessive sodium antimonate contains copper of 0.005 wt% or more.

7. The process for low temperature, rapid de-coppering of sodium antimonate according to claim 1 or 2, characterized in that, When the Cu content in the reaction mother liquor is less than 5 mg / L, the reaction mother liquor can be recycled as the composite copper removal reagent or the water solvent in the next time; and when the Cu content in the reaction mother liquor is 5 mg / L or more, TMT chelation precipitation method is used for copper precipitation treatment.

8. The process for low temperature, rapid decopperization of sodium antimonate according to claim 3, characterized in that, When the Cu content in the reaction mother liquor is less than 5 mg / L, the reaction mother liquor can be recycled as the composite copper removal reagent or the water solvent in the next time; and when the Cu content in the reaction mother liquor is 5 mg / L or more, TMT chelation precipitation method is used for copper precipitation treatment.

9. The process for low temperature, rapid decopperization of sodium antimonate according to claim 1 or 2, characterized in that, The copper-removed sodium antimonate is washed with a washing mother liquor for one time or more to obtain a copper-removed sodium antimonate product; the washing mother liquor is a dilute solution of urea, and the urea content is 0.8 wt%-1.5 wt%, and the Cu content is less than 5 mg / L; when the Cu content in the washing mother liquor after washing is less than 5 mg / L, the washing mother liquor can be recycled as the washing mother liquor in the next time; and when the Cu content in the washing mother liquor after washing is 5 mg / L or more, TMT chelation precipitation method is used for copper precipitation treatment.

10. The process for low temperature, rapid decopperization of sodium antimonate according to claim 3, characterized in that, The copper-removed sodium antimonate is washed with a washing mother liquor for one time or more to obtain a copper-removed sodium antimonate product; the washing mother liquor is a dilute solution of urea, and the urea content is 0.8 wt%-1.5 wt%, and the Cu content is less than 5 mg / L; when the Cu content in the washing mother liquor after washing is less than 5 mg / L, the washing mother liquor can be recycled as the washing mother liquor in the next time; and when the Cu content in the washing mother liquor after washing is 5 mg / L or more, TMT chelation precipitation method is used for copper precipitation treatment.