Study On The Chemical And Physical Property Change In The Process Of Magnesium Removal From Phosphate Rock By Leaching

In this paper, the change of chemical and physical properties of phosphate rock during leaching for magnesium removal was studied. The data of basic physical and chemical properties of four different samples collected were analyzed by chemical methods and characterizations such as laser particle size analyzer, XRD, XPS, SEM, BET, electron probe analysis and so on. The orthogonal experiments of magnesium removal from phosphate rock were designed referring to the parameters of reaction temperature, reaction time, the ratio of liquid to solid, stirring rate. The process of magnesium removal was optimized based on the magnesium removal rate and phosphorus loss rate. Under optimum conditions, the content of chemical composition and the structure and properties of phosphate were studied, which provided guidance for magnesium removal from phosphate rock.The chemical physical properties of different phosphate rocks were found different.Through the orthogonal experiments, the process of magnesium removal from low magnesium phosphate was as followed:reaction temperature of 40℃, stirring rate 300 r/min, liquid to solid ratio of 5:1 cm3/g, reaction time of 30 min, phosphate rock particle size 80 to 120 mesh, pH is controlled in the range of 2～3; the process of removing magnesium from high magnesium phosphate was as followed:reaction temperature of 50℃, stirring rate 300 r/min, liquid to solid ratio of 5:1 cm3/g, reaction time of 40 min, phosphate rock particle size 80 to 120 mesh, pH in 2-3.The process of removing magnesium from phosphate was studied under the optimized working conditions. The results of removing magnesium from low magnesium phosphate were as followed. The removal rate of MgO was 94.30%; The removal rate of CaO was 2.48%; The removal rate of Al2O3 was 50.40%; The removal rate of Fe2O3 was 29.10%; The removal rate of Na2O was 53.72%; The removal rate of K2O was 17.74%; The results of removing magnesium from high magnesium phosphate were as followed:The removal rate of MgO was 98.5%; The removal rate of CaO was 5.71%; The removal rate of Al2O3 was 35.71%; The removal rate of Fe2O3 was 18.25%;The removal rate of Na2O was 70%;The removal rate of K2O was 37.69%.In early stage of the reaction, the reaction of removing magnesium from low magnesium phosphate rock mainly occurred on the surface of the ore particles. The reaction of removing magnesium from high magnesium phosphate rock mainly occurred on the surface and interior of the ore particles. In the middle stage of reaction, the sphere -shaped or rod-shaped products formed on the surface of the ore particles. The size distribution and pore structure of particles changed, lasting to the end of the reaction. In the later stage of the reaction, dolomite was acid-hydro lyzed. The chemical composition of the remaining particles was apatite and silicate. The aim effectiveness of magnesium removal and phosphorus retention has mainly reached.