Study On The Production Of Mineral Potassium Fertilizer By Using Potassium Feldspar By Hydrothermal Method

China is one of the world's largest sylvite and potashfertilizer demand countries,the consumption of potash fertilizer has always been greater than that of production,and the external dependence of potash fertilizer is about 50%.The rational development and utilization of abundant domestic insoluble potash bearing to make potash,actively carry out research process of potassium,can make up for the lack of domestic shortage of soluble potash resources to a certain extent,ease the contradiction between supply and demand of domestic potash fertilizer.Potash feldspar is a kind of potassium-feldspar with high potassium content and extremely rich and difficult to dissolve potassium-containing silicate minerals.In this paper,potassium-feldspar with low potassium content in Leshan Ebian Wudou of Sichuan Province is studied by hydrothermal reaction element mineral fertilizers.In this paper,XRD and XRF analysis of K-feldspar were studied.The main chemical constituents of the ore were SiO2,Al2O3 and K₂ O.The phase composition is Microcline,quartz,soda feldspar.The results of different particle size ore analysis show that the content of SiO2 in the content of silicon decreases gradually from 67.90% to 69.31% with the decrease of mineral size,while the content of K₂ O increases slightly in the range of 9.57% to 10.19%.Microcline content in the range of 56.61% to 60.27% increase in the trend.The average K₂ O content is about 10%.The potassium content of available K₂ O dissolution rate and product in fertilizer as the evaluation criteria,the process conditions were optimized by single factor method.The results showed that the solubility of K and the content of effective K₂ O in the product increased with temperature,pressure,solid ratio and time.The process conditions were determined: the calcium oxide was used as the promoter,the molar ratio of Ca/?Si+Al?was 1,the liquid to solid ratio was only about 1.8: 1,the reaction temperature was 250?,the pressure was 8Mpa,the reaction time was 20 h.After the hydrothermal reaction,the dissolution rate of potassium can reach 85%,and the content of K₂ O in the product is up to 4.76%.By XRD,XRF analysis shows that the product of fertilizer is comprised of tobermorite?Ca5Si6O18·5H2O?and hibschite?Ca3Al2?SiO4??OH?8?and kilchoanite?Ca4Si3O10·2H2O?,potassium exists in the form of KOH.0.5mol/L hydrochloric acid solution and distilled water were used as leaching agent to extract the product.The results of ICP-OES analysis showed that the effective components of the fertilizer were:more than 4% soluble potassium?K₂O measurement,including water soluble and insoluble?;more than 25% citric acid soluble silicon?in SiO2 measurement?;more than 44% citric acid soluble calcium?CaO measure?and the total content of more than 0.4% citrate soluble trace elements of iron and magnesium,zinc and boron manganese;The time of release of potassium in the product was investigated.The release rate of water-soluble potassium in the product was slow,which may be caused by the inclusion of calcium and other insoluble components in the fertilizer.Potassium soluble in the role of acid under the release rate faster.The appearance of the product was determined.The bulk density was about 0.65 g/cm3,which was consistent with the conclusion that the product structure was loose and the number of micron pore size existed.The product has a pH of 11 and is suitable for acidic soils.The moisture content of the product is less than 0.5%.The decomposition mechanism of potassium feldspar in hydrothermal reaction were discussed.XRD analysis of solid reactants at different time points shows that Ca2+ in the reaction auxiliaries exchanges K+ and OH-in K-feldspar to destroy the crystal structure of potassium feldspar,The original oblique feldspar changed to transition state C-S-H gel,C-S-H and then converted to the final terbutaline and orthorhombic silica,Al2O3 and part of the SiO2 and CaO in the hydrothermal conditions formed water calcium aluminum garnet.Through the experiment of soil cultivation,the fertilizer effect of the product fertilizer on the crop was obvious,which was beneficial to the increase of yield,and neutralized the acid soil,which was beneficial to the growth of root system.Preliminary validation of the product's fertilizer efficiency.