Study Of The Hanyuan Phosphate-potassium Ore's Characteristics And Reaction Mechanisms On Producing Compound Fertilizer

Nitrogen, phosphorus and potassium are three kinds of the main chemical elements necessary for agriculture. Though China is rich of phosphate reserves, most of the storage is middle or low-grade phosphate ores. And, China's dissoluble potassium resources are very scarce. In China, Fertilizer production is imbalance. The output of potassic fertilizer is comparatively low.It is very urgent to utilize low-grade phosphate ores and insoluble potassium resources to produce phosphorus-potassium compound fertilizer. Hanyuan phosphor-potassium ore is the only and the biggest ore of china, which contains phosphor and potassium simultaneously. The comprehensive utilization of Hanyuan phosphor-potassium ore may have industrial significance and prospects for commercialization.Hanyuan phosphor-potassium ore is low-grade with high-impurity. The potassium in the potash feldspar is insoluble. So, there have many difficulties in the studies of it.A new process of utilizing Hanyuan phosphor-potassium ore to produce compound fertilizer was proposed: First, potash feldspar was sintered with high temperature to transform insoluble potassium in potash feldspar into available potassium. Second, the baked ore was decomposed by sulfuric acid to produce phosphoric acid and extracting dissoluble potassium from the baked ore. The last step was ammoniation of the wet process phosphoric acid. The product obtained is a compound fertilizer, which contain N, P2O5 and K2O.The mineralogical compositions of Hanyuan phosphor-potassium ore are analyzed by both chemical and X-ray diffraction methods. The results indicate that Hanyuan phosphor-potassium ore is a low-grade ore. The contents of P2O5 and K2O are 13.11% and 6.76% respectively. The phase compositions are Ca3(PO4)F, KAlSi3O8, SiO2 and CaMg(CO3)2-The technological characteristics of the Hanyuan phosphate-potassium ore, including reactivity, resistance to block and foaming ability, are investigated. Compared with other phosphate ores, the reactivity of the Hanyun phosphate-potassium ore is lower. Its resistance to block is worse and the foaming ability is strong.Structure determination or characterization is the first and vital step in most materials reaserch. Cerius2 (MSI, USA) provides a perfect tool to analyze crystalline structure using advanced computational methods. Cerius also supplies a platform to build, view, and geometrically measure three-dimensional models of crystalline structure.The crystalline structure of potash feldspar powders sintered at different temperatures of 900, 1000, 1100 and 1200 was studied by means of X-ray diffraction. A series of structure parameters, such as crystalline size, micro-strain, square shift of atom, dislocation density and crystallinity, were calculated by Neaton-Raphson calculating method in Cerius2 to characterize the crystalline structure of the potash feldspar in Hanyuan phosphor-potassium ore at atom level. The results show that with rising of the sintered temperature, the micro-strain, square shift of atom and dislocation density increase, but crystalline size and crystallinity decrease. All of these parameters indicate that the potash feldspar in Hanyuan phosphor-potassium ore become more activated with the rising of sintering temperature. These results can be used to explain that it was become easier for extracting dissoluble potassium from the potash feldspar with the rising of sintering temperature.The process of the potash feldspar in Hanyuan phosphor-potassium ore withCaSO4 H2O, CaCO3, and the mixture of CaSO4 H2O and CaCO3 sintered at different temperatures of 900, 1000, 1100 and 1200 was studied respectively. The sintered reaction mechanisms of potash feldspar with CaCO3 and the mixture of CaSO4H2O and CaCO3 were discussed in detail.The main factors that affect the leaching rate of potassium in the process of Hanyuan phosphor-potassium ore sintered with the mixture of CaSO4H2O and CaCO3 were studied. The optimum operation conditions for the process were confirmed as follow:m(Hanyuan phosphor-potassium ore):m(CaSO4 H2O):m(CaCO3)=l .0.6:...