| CPC C01B 25/45 (2013.01) [H01M 4/366 (2013.01); H01M 4/5825 (2013.01); H01M 4/587 (2013.01); C01P 2004/80 (2013.01); C01P 2006/40 (2013.01)] | 7 Claims |
|
1. A method for preparing lithium iron phosphate using by-product ferrous sulfate from titanium dioxide, characterized in comprising the following steps:
(1) adjusting pH of water to a range of 1.5-2.0 by adding sulfuric acid, then dissolving by-product ferrous sulfate from titanium dioxide in the water to prepare a saturated solution; adding iron powder into the saturated solution, and stirring the iron powder in the saturated solution for reacting at a temperature of 80-90° C. for 2-3 hours until the pH of the saturated solution is 2 to obtain a first mixture, precipitating and settling the first mixture to obtain a supernatant, wherein the supernatant is a ferrous sulfate solution;
(2) adding iron phosphate or lithium iron phosphate waste powder to the ferrous sulfate solution, stirring the phosphate or the lithium iron phosphate waste powder in the ferrous sulfate solution at a temperature of 80-90° C. for 30-60 minutes to obtain a second mixture, allowing the second mixture to settle and cool to below 40° C., and filtering the second mixture to obtain a purified ferrous sulfate solution;
(3) dissolving lithium hydroxide in water, adding phosphoric acid and a lithium hydroxide solution in a co-current manner in an autoclave for neutralization; subsequently, adding the purified ferrous sulfate solution to obtain a third mixture, heating the third mixture under stirring, then filtering, washing, and drying the third mixture to obtain lithium iron phosphate powder;
wherein in step (2), an amount of the iron phosphate or lithium iron phosphate waste added is 2-3 wt % of a mass of ferrous sulfate in the ferrous sulfate solution.
|