Lithium batteries can be divided into lithium iron phosphate battery, lithium manganate battery, lithium cobaltate battery, ternary lithium battery, and so on, according to their different anode systems. With the decline of national subsidies for new energy vehicles, and taking the safety of lithium iron phosphate and the economy brought by long cycle into consideration, its thermal run away temperature is much higher, and its safety is also much higher. Therefore, under the cost control, its safety advantage also makes its demand rise.
Iron phosphate is a key precursor material of lithium iron phosphate, its main process is to fully grind and mix iron phosphate precursor with lithium source and carbon source. Then carbon thermal reduction method is used to produce the positive electrode materials iron phosphate lithium. The quality of iron phosphate materials will largely determine the overall performance of iron phosphate lithium positive electrode materials.
Enterprises in the market mainly produce iron phosphate by using ferrous sulfate and ammonium dihydrogen phosphate, the cost is relatively low and the raw materials are extremely easy to obtain. Among them, iron source ferrous sulfate is mostly a by-product of waste produced in the production of titanium dioxide enterprises, while phosphorus source ammonium dihydrogen phosphate is a raw material of agricultural phosphate fertilizer. But phosphoric acid needs to be purified to obtain high-quality ammonium dihydrogen phosphate.
At present, phosphoric acid is mainly produced by thermal process and wet process: Phosphoric acid produced by thermal process is mainly used in chemical industry and food industry, but its production process has high energy consumption, complex equipment and serious pollution. With the requirement of economic development for energy conservation and environmental protection, the thermal process of high energy consumption and high pollution phosphoric acid production process is gradually replaced by the wet process of low energy consumption. The production of wet process phosphoric acid accounts for about 85% ~ 90% of total phosphoric acid production in the world. However, impurities like fluorine, sulfur, iron, aluminum, magnesium, calcium and so on in raw phosphate rock will enter into the finished phosphoric acid during the production of wet process phosphoric acid. So if high-quality phosphate products are to made from wet process phosphoric acid, it is necessary to carry out deep purification treatment on impurity ions.
The main methods of removing ions from wet process phosphoric acid are: solvent precipitation, solvent extraction, ion exchange, cooling crystallization, etc. Among which, solvent precipitation and solvent extraction need to add solvent, which increase the treatment process steps and energy consumption of solvent recovery. Ion exchange requires large amount of resin and the production cost is high. Cooling crystallization has a low product yield and requires multiple crystallization to obtain high purity phosphoric acid. Therefore, Guochu Technology successfully developed a special technology for phosphoric acid purification. This technology uses nano-scale physical separation method to remove metal impurity ions without phase conversion, thus reducing the operating time, energy consumption and equipment area, and improving phosphoric acid purification efficiency. Most importantly, the operating costs are almost negligible.
Technical features and advantages:
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Suitable for phosphoric acid purification with high acid concentration and high ionic impurity content;
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Heating and pressurization are not needed in the process of phosphoric acid purification, which is safe and reliable, and has very low energy consumption;
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Both phosphoric acid recovery rate and concentration of recovered phosphoric acid have advantages.
There are many kinds of impurities in wet process phosphoric acid, and the quality requirements of feed grade, food grade and technical grade are different. Different purification methods can be selected according to the actual demand. If a single purification technology cannot meet the demand of phosphoric acid purity, two or more purification technologies can be used to give play to the advantages of various purification technologies. In addition, with the development of microelectronics industry, the demand of high purity electronic grade phosphoric acid will be increasing.
Guochu Technology will also continue to explore new technologies of higher purity phosphoric acid purification
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