Cement Additive from Phosphogypsum

A production line using industrial waste phosphogypsum to produce cement additive was completed and put on stream in Shaanxi Huashan Chemical Group Compound Fertilizer Plant on Sept. 4. It can digest 700 tons of phosphogypsum a day and produce 200 000 tons of cement additive a year.    Huashan Chemical Group Compound Fertilizer Plant is a production base of high-effect compound phosphate fertilizers in Shaanxi established in 1990. It discharges around 300 000 tons of phosphogypsum a year. The stock yard has expanded from 40 hectares in the first years to 200 hectares today. Not only several million RMB of transportation cost but also high environmental protection expenses have to be spent a year.    Shaanxi Huashan Chemical Group cooperated with Shaanxi Weinan Jiangyou Co., Ltd. in 2004 and made a joint investment of RMB18 million to construct a production line using phosphogypsum to produce cement additive. Phosphogypsum is first washed with water and then evenly agitated and heated with lime additive at a certain ratio. Hazardous substances in phosphogypsum are therefore transformed into phosphates and silicates. Granulation is finally conducted to get granular cement coagulation inhibitor to replace natural dehydrated gypsum.