Effect Of The Quality Of Phosphogypsum On Phosphogypsum Composite Binder

Phosphogypsum is a by-product of industrial production of wet process phosphoric acid. Due to the different rock phosphates or different production process conditions, the quality of phosphogypsum fluctuates strongly. Moreover according to the national standard, phosphogypsum can be divided into two levels. But the previous experimental results show that the performance of gelled material or product is different from the same level of phosphogypsum. So this article focuses on the quality(including particle size, PH value, impurities) of original phosphogypsum, the effect of the quality of phosphogypsum on phosphogypsum composite binder was also studied.This study used phosphogypsum without calcination, adding other materials to produce composite binder. The best base mixture ratio is phosphogypsum 60%, cement 10%, fly ash 26%, lime 4%, polycarboxylic acid water-reducing agent 0.2%, and the best curing system is 10 hours steam curing under 75℃ and then laboratory environment curing. Through grinding phosphogypsum, regulating phosphogypsum PH value, adjusting content of soluble phosphorus and soluble fluorine, we can explore the effect of quality of phosphogypsum on phosphogypsum composite bind er. Experimental results show that at the time of preparation of phosphogypsum composite binder, average particle size of phosphogypsum is best controlled under 35 μ m, PH values is between 5~7 and soluble phosphorus is under 0.6%, soluble fluoride is under 0.3%. In the production practice, the PH value and soluble phosphorus and soluble fluoride of phosphogypsum are allowed to adjust reasonably because of adding 4% lime and steam curing, and the soluble phosphate can be modulated to less than 1%, the soluble fluoride can be modulated to less than 0.5%. Finally using high-performance phosphogypsum composite binder, adding proper amount of fiber, we can prepare the fiber gypsum boards, compared with the ordinary plasterboard, its fracture energy can improve 1 6 times and its water absorption can fall 2/3. And by adjusting the fineness of phosphogypsum, can prepare different strength grade of gypsum board. And by adjusting the fineness of phosphogypsum, we can prepare different strength grades of gypsum board.This study used 60% raw material is phosphogypsum which our country urgently awaits to be solved in the present stage, and it will greatly reduce energy consumption that the without preprocessed, non-calcined phosphogypsum was used. So this study has positi ve meaning to the actual production and the sustainable development of resources.