Preparation and application of calcium oxalate_Kain Industrial Additive

Background and overview^[1][2]

Molecular weight 128.10. Colorless cubic crystal. Relative density 2.2. Its monohydrate is a colorless crystal with a relative density of 2.2. It loses water when heated to 200°C. Insoluble in water and acetic acid, soluble in nitric acid and hydrochloric acid, it generates CaCO₃ or CaO upon ignition and heating. Preparation method: Prepare a dilute aqueous solution with refined CaCl₂, heat it with the oxalic acid aqueous solution to react with each other, and precipitate. After dissolving in hot hydrochloric acid, add ammonia water to precipitate again, and then wash the latter with hot water. , dried at 105°C to obtain monohydrate. Place the monohydrate in a dry airflow at 250°C and obtain anhydrous product after constant weight. Usage: It can be used to make oxalic acid. It is mostly used in industry to make lubricating oil esters, waterproofing agents, etc.

Preparation^[2-3]

A method for producing calcium oxalate using calcium carbide slag, including the following steps: grind the calcium carbide slag into a coarse powder of 80-100 mesh, place it in a reactor and mix it thoroughly with water, and then put excess hydrochloric acid into the reactor , convert the oxides in the carbide slag into soluble chlorides, and then filter the reaction product to obtain a filtrate containing mainly calcium chloride. The filtrate also contains a small amount of aluminum chloride and ferric chloride; it will be chlorinated The calcium-based filtrate reacts with excess carbonic acid solution, and calcium ions combine with carbonate ions to form calcium carbonate and precipitate. However, in a water environment, iron carbonate cannot be obtained, and aluminum carbonate is also easily hydrolyzed, thus calcium ions are Separate from magnesium ions and aluminum ions in the form of calcium carbonate precipitation, and obtain calcium carbonate filter cake after filtration; then react the calcium carbonate filter cake with oxalic acid to obtain a mixture of calcium oxalate precipitation and carbonic acid solution; the mixture of calcium oxalate precipitation and carbonic acid solution The mixture is separated by filtration to obtain carbonic acid filtrate and calcium oxalate filter cake; the carbonic acid solution is returned to react with the filtrate mainly composed of calcium chloride; and the calcium oxalate filter cake is dried and pulverized to obtain calcium oxalate product. The method of producing calcium oxalate from calcium carbide slag according to the present invention can effectively extract the calcium contained in the calcium carbide slag, which provides a new way for the industrial application of calcium carbide slag. The method is simple and has low equipment investment, and is worthy of promotion and application. method.

A method for producing industrial calcium oxalate and phosphoric acid using phosphogypsum. The method includes the following specific steps: crush the phosphogypsum into a coarse powder of 80-100 mesh, place it in a reactor and mix it thoroughly with water to make the phosphogypsum The soluble impurities are dissolved in water and then filtered to obtain filter residue one and filtrate one; filter residue one is all water-insoluble impurities, which mainly contains calcium sulfate, calcium phosphate, and a small amount of other insoluble impurities such as fluoride, fluorine, aluminum, Magnesium phosphates and sulfates, etc.; react filter residue one with excess sulfuric acid. At this time, the calcium phosphate in filter residue one reacts with sulfuric acid to generate insoluble calcium sulfate and soluble phosphoric acid. After filtration, filter residue two and filtrate two are obtained; filter residue two It mainly contains calcium sulfate and a small amount of other insoluble impurities such as fluoride, phosphates and sulfates of fluorine, aluminum and magnesium. The filter residue reacts with excess hydrochloric acid. At this time, the insoluble calcium phosphate is converted into soluble phosphoric acid and chlorine. Calcium, insoluble fluorine, aluminum, and magnesium phosphates are also converted into soluble phosphoric acid and chloride; the reactants are filtered again to obtain filtrate three and filter residue three mainly containing calcium sulfate and a small amount of sulfate; the obtained filter residue three is washed and dried After grinding, high-purity calcium sulfate is obtained; the obtained high-purity calcium sulfate is mixed with water and reacted with oxalic acid to obtain calcium oxalate precipitate and sulfuric acid, which are separated by filtration to obtain calcium oxalate filter cake and sulfuric acid filtrate; the sulfuric acid solution is returned to the The filter residue is reacted and reused; the obtained calcium oxalate filter cake is washed, crushed and dried to obtain calcium oxalate product.

Apply^[4-5]

1. Used to prepare a calcium oxalate modified polymer fire extinguishing agent

In view of the shortcomings of existing polymer fire extinguishing agents that will cause secondary combustion of combustibles due to decomposition after fire extinguishing, and cannot be effective for a long time, CN201610568563. Calcium oxide reaction is used to prepare nano-calcium oxalate, which is then ball-milled, coupled and modified, and filled to prepare a polymer calcium oxalate composite material. Through high-temperature decomposition of calcium oxalate, a large amount of carbon dioxide is generated, which is continuously deposited on the surface of combustibles, effectively preventing combustibles from interacting with oxygen. contact to prevent secondary combustion, effectively solving the shortcomings of existing polymer fire extinguishing agents that will cause secondary combustion of combustibles due to decomposition after extinguishing the fire, and cannot be effective for a long time. In order to solve the above technical problems, the technical solution adopted by the present invention is:

(1) According to the mass ratio of 1:10, stir aminotriacetic acid and sodium hydroxide solution with a mass concentration of 30% and place them in a beaker. After letting it stand for 10 to 15 minutes, add 1 mol/L dropwise to the beaker. Hydrochloric acid solution, adjust pH to 8.0 to prepare alkaline aminotriacetic acid solution;

(2) In terms of parts by weight, weigh 10 to 15 parts of 0.5 mol/L calcium chloride solution, 50 to 60 parts of the alkaline aminotriacetic acid solution prepared above, and 20 to 25 parts of 0.5 mol/LK2C2O4. Place the solution in a beaker, stir and mix, and add dropwise a 10% hydrochloric acid solution. After adding dropwise until no precipitation occurs, let it stand for 10 to 15 minutes and centrifuge at 1800 to 2200 r/min for 5 to 10 minutes. Collect the lower precipitate and use it. Wash with deionized water 3 to 5 times, and then dry at 65 to 80°C for 6 to 8 hours to prepare calcium oxalate powder;

(3) According to the mass ratio of 1:10, stir and mix 3-aminopropyltriethoxysilane and calcium oxalate powder and place them in a ball millSoil will swell when absorbing water. Urea and oxalic acid are dissolved and dispersed in the bentonite that expands after absorbing water. During the water loss process of the mixed material, urea and oxalic acid gradually crystallize in the bentonite structure, improving the dispersion of urea and oxalic acid in the bentonite. Stability, after emulsification and dispersion in polyvinyl benzene solution, the uniform dispersion stability of bentonite in polyethylene can be improved; the prepared bentonite modified polyethylene has excellent uniform dispersion stability and pore-forming performance, which improves the thermal insulation and has low Thermal conductivity of thermally conductive polyethylene materials;

2. Oxalic acid, calcium oxalate and urea are dispersed in ethanol solution and emulsified and dispersed with polyethylene benzene solution, which can improve the dispersion in polyethylene; the prepared calcium oxalate modified polyethylene has excellent dispersion and pore-forming properties to improve the thermal conductivity of low thermal conductivity polyethylene materials for thermal insulation;

3. The ethanol solution of urea is emulsified and dispersed in the polyvinyl benzene solution, which can improve its dispersion stability in polyethylene; the prepared urea-modified polyethylene has excellent dispersion stability and improved pore-forming performance Thermal conductivity of low thermal conductivity polyethylene materials for thermal insulation;

4. After emulsification and cross-linking of tetraethyl silicate and sodium silicate through Sr-10 emulsifier and A171 silane coupling agent, the emulsification and dispersion of the silica airgel precursor can be significantly improved. The porosity of silica aerogel. The prepared silica aerogel can improve the porosity of polyethylene materials; the prepared silica aerogel can improve low thermal conductivity polyethylene for thermal insulation due to its excellent porosity and specific surface area. Thermal conductivity of material;

5. Under the synergistic effect of fumed silica-modified polyethylene, urea-modified polyethylene, calcium oxalate-modified polyethylene and bentonite-modified polyethylene, low thermal conductivity polyethylene materials for thermal insulation are given excellent low thermal conductivity. .