磷石膏漂白—煅烧增白工艺研究

磷石膏已成为制约磷化工行业可持续发展的重要因素。磷石膏除杂增白是实现其规模化应用于建材和填料的必经途径。本文采用漂白—煅烧法对某地浮选后的磷石膏进行处理，在漂白浸出温度90℃、液固比4：1、Ca（ClO）2用量为3.0%和浸出时间3.0 h条件下，漂白磷石膏的白度由51.5%增加到了74.5%，将漂白后的磷石膏在600℃下恒温煅烧120 min，得到煅烧磷石膏的白度为86.1%，增白效果显著，满足粉刷石膏和PVC/PE填料等要求。煅烧磷石膏主要成分是CaSO4，并呈表面光滑、大小不一的不规则片状结构。本研究对磷石膏规模化综合利用具有重要的指导意义。

Study on Whitening of Phosphogypsum via Bleaching and Calcination

Phosphogypsum have has become the important factor that restricts the sustainable development of phosphorous chemical industry. Removal impurity and whitening of phosphogypsum is the only way to realize its large-scale utilization in building materials and fillers. In this paper, the phosphogypsum after flotation was treated by bleaching and calcination. Under the conditions of leaching temperature of 90 ℃, liquid-solid ratio of 4:1, Ca(ClO)₂ dosage of 3.0% and leaching time of 3.0 h, the whiteness of bleached phosphogypsum increased from 51.5% to 74.5%. Furthermore, the whiteness of the whitened phosphogypsum significantly reached 86.1% after calcining at 600 ℃ for 120 min, which met the requirements of gypsum plaster and PVC filler. The main component of phosphogypsum after calcination was CaSO₄, which was an irregular sheet structure with smooth surface and different sizes. This study has an important guiding significance for the large-scale comprehensive utilization of phosphogypsum.