Preparation method of optical lithium metaphosphate

Abstract

The invention provides a preparation method of optical-grade lithium metaphosphate. The preparation method comprises the following steps: (T1) preparing polymer graft modified polydopamine coated SiO2 microspheres as an adsorbent; (T2) enabling a solution of crude lithium dihydrogen phosphate to sequentially pass through activated carbon and the modified SiO2 microspheres obtained in the step (T1) to remove impurities, filtering and concentrating to obtain a lithium dihydrogen phosphate concentrated solution; (T3) carrying out spray calcination on the lithium dihydrogen phosphate concentrated solution obtained in the step (T2) to obtain lithium metaphosphate intermediate powder; and (T4) continuously calcining the lithium metaphosphate intermediate powder at 800-850 DEG C to obtain the optical-grade lithium metaphosphate. The alkenyl monomer containing crown ether groups, the unsaturated carboxylic acid monomer, the unsaturated sulfonic acid monomer and the temperature-sensitive monomer are polymerized and grafted on the surfaces of the SiO2 microspheres coated with the polydopamine, and finally, the prepared lithium metaphosphate is high in purity and suitable for being used as a raw material of high-end optical glass.

Description

technical field [0001] The invention belongs to the field of optical glass raw material metaphosphate chemical industry, in particular to a preparation method of optical grade lithium metaphosphate. Background technique [0002] Optical grade high-purity lithium metaphosphate is one of the main raw materials for optical glass. Currently, lithium phosphate and hydrochloric acid are usually used to prepare lithium dihydrogen phosphate, or lithium bicarbonate and phosphoric acid to prepare lithium dihydrogen phosphate, and then calcined at high temperature. But no matter what method, basically, high-purity lithium dihydrogen phosphate is prepared first, and then calcined to prepare lithium metaphosphate. The main defects of such methods in the prior art are: first, the content of non-ferrous metals in the obtained lithium metaphosphate is still relatively high, which cannot meet the needs of high-end optical glass, such as high-end cameras, national defense scientific research ...

AI Technical Summary

Problems solved by technology

[0006] In order to solve the incomplete removal of hetero ions that affect the optical performance in the preparation process of lithium metaphosphate in the prior art, especially the removal effect of Fe and Cu ions is not good enough, or the defects of high removal cost, the present invention proposes an optical grade polarizer The preparation method of lithium phosphate adopts SiO2 modified by polymer grafting 2 As an adsorbent, the microspheres were put into the crude lithium dihydrogen phosphate solution and passed through the SiO 2 The polydopamine on the surface and the polymer grafted on the surface of polydopamine work together to absorb the non-ferrous metal ions in lithium dihydrogen phosphate, and then prepare lithium metaphosphate. Preparation of high-end optical glass

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