The Study On The Activation Of Low Grade Phosphate Rock Using Calcium Base Solid Waste And Its Application

Phosphate rocks are crucial nonrenewable resources and are essential components infertilizers and phosphorous based chemicals. In recent years, a large amount of high gradephosphate rock was mined for a long time. During the process of mining and mineralprocessing there is a tremendous amount of accumulating abandoned mine, which are mostlylow grade phosphate rock, whose average grade is only17%. These abandoned mine not onlytake up a lot of land and pollute the environment, but also cause the waste of resources andpotential safety hazard. Therefore, how to reasonably use the large amount of the low gradephosphate rock and change these waste materials into things of value have become animportant problem to be solved.The soil amendment was prepared by calcinating a mixture of low-grade rock phosphate,dolomite and phosphogypsum with fusing agent. The optimum material mass ratio oflow-grade rock phosphate, dolomite and phosphogypsum was5:1:1.2, and the optimumreaction conditions was roasting90min in1373K with3.0wt.%fusing agent. The contents ofnutrient elements in the soil amendment were P₂O₅22.56%, CaO45.10%, MgO4.28%, SiO₂17.24%, SO₃3.97%and Na₂O1.82%. Its pH value was10.16. The contents of heavy metaland radioactivity were far lower than the national standard, so it do not harm to theenvironment.In the pot growing, the soil amendment, white mud and flue gas desulfurization residue（FGDR） were applied to the pot at four application rates,1g/kg （1‰）,2g/kg （2‰）,3g/kg（3‰）,4g/kg （4‰） and control （CK）. The positive effect order of three material was the soilamendment> FGDR> white mud. The optimized application rate were the P-rich soilamendment （3‰）, FGDR （4‰）, white mud （4‰）. The soil amendment can increase the soilpH value, the content of organic matter, exchangeable calcium and exchangeable magnesium.It can also reduce the content of exchangeable aluminium and significantly improve the planton phosphorus absorption efficiency.The method of this thesis can not only solve the problem of low utilization rate of lowgrade phosphate rock and high land occupation of phosphogypsum, but also make full use of the various elements in the raw material to make a kind of soil amendment.