Preparation method of low-chromium feed-grade MDCP

The invention discloses a preparation method of low-chromium feed-grade MDCP, which comprises the following steps: mixing secondary washing water of a wet-process phosphoric acid rotary table filter with calcium oxide powder, stirring the mixture for a reaction, carrying out standing, filtering to obtain low-chromium feed-grade DCP, and adding defluorinated phosphoric acid to obtain a low-chromiumfeed-grade MDCP product. According to the method, the content of chromium in the feed-grade MDCP can be greatly reduced, a low-chromium feed calcium product is obtained, the requirements of GB/T22549-2017 are met, meanwhile, the content of water-soluble phosphorus and fluorine in the phosphogypsum is greatly reduced, a wider space is provided for comprehensive utilization of the phosphogypsum, and the economic and environment-friendly benefits are remarkably improved. 本发明公开一种低铬饲料级MDCP的制备方法，用湿法磷酸转台过滤机二洗水与氧化钙粉混合搅拌反应，静置过滤后得到低铬饲料级DCP，加入脱氟磷酸，得到低铬饲料级MDCP产品；本发明可大幅度降低饲料级MDCP中铬的含量，获得低铬饲料钙产品，满足GB/T22549-2017要求，同时，大幅度降低磷石膏中的水溶磷