Research on the preparation of high-purity sodium carbonate

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This post was last edited by sunjl1981 on 2013-1-6 21:44. Sodium carbonate (Na2CO3) is one of the basic industrial raw materials; it is used in the production of other sodium compounds and is widely applied in industries such as metallurgy, papermaking, glass manufacturing, ceramics, food processing, dyes, and detergents, as well as in daily life. It holds a crucial position in the national economy. With the rapid development of the electronics industry both domestically and internationally, the high-purity sodium carbonate available in the past is far from meeting the extremely stringent quality requirements. Moreover, there are very few literature reports on this topic. Therefore, we had to redesign, innovate, and improve upon previous purification methods, and as a result developed a new process for producing high-purity sodium carbonate. The quality of the product obtained meets all the purity standards required for electronic-grade sodium carbonate; it can be used in the production of television phosphors, as well as in electronic glass and photochemical glass, making it highly valuable for widespread application. 1 Experimental Section 1.1 Raw Materials “Yandu” brand industrial-grade soda ash ； Carbon dioxide gas ； Reagents: sodium sulfide, ammonium phosphate, disodium EDTA, activated carbon ； Home-made complexing accelerator M. 1.2 Instruments: high-speed centrifuge, ball mill, atomic absorption spectrophotometer. 1.3 Purification method: In a reactor equipped with stirring, 400 mL of deionized water is added and the mixture is heated to 50±2°C. Then, 120 g of industrial-grade sodium carbonate brand “Yandu” is added while stirring, and stirring continues until complete dissolution. Subsequently, water-insoluble impurities are removed by filtration. Return the mother liquor to the cleaned reactor, add an appropriate amount of sodium sulfide and ammonium phosphate, and carry out chemical purification ； Stir well to ensure that impurity ions such as Cu2+, Mg2+, and Pb2+ in the mother liquor react completely with sodium sulfide and ammonium phosphate, thereby fully forming precipitates of MgNH4PO4, CuS, and PbS; then filter ； Add the measured amount of disodium EDTA and an appropriate amount of complexation accelerator to the chemically purified mother liquor, stir to dissolve it, maintain the temperature at around 45°C, and slowly introduce carbon dioxide gas until the pH is reached