The Investigation On Mechanism And Thermodynamics Of Extracting Potassium From Potassium Feldspar By Fluoride Chemical Method

Potash is one of the necessary fertilizers in agricultural production which comes from potassium resources in saline lakes mostly.However,due to the rarely water soluble potassium in our country,the supply of potash is not adequate to the demand of it that restricts the development in all aspects in society depending on imports over a long period of time.It is widely distributed in our country that potash feldspar stands for the non water soluble potassium;whereas the technology of extracting potassium from potash feldspar is restrained by some problems such as high energy consumption,high pollution,low economic benefits and so on.Thus,it is the key to solve the condition that is the rarely potash by some craftwork of utilizing potash feldspar in low consumption,low cost,lighter pollution.Based on fluorine chemical method,the mechanism and thermodynamics study of corroding potassium feldspar to extract potassium were investigated in this thesis.We compared the results from potassium feldspar ore and potash feldspar corrosion by fluorine chemistry by XRD,IR and SEM;then it comes out the crystal structure of Si-O-Al net potassium feldspar dense fluoride hydrogen corrosion damage and the formation of AIF3,KF,K2SiF6 and SiF4,and finally can extract soluble potassium from sulfate in further reaction with sulfuric acid.Moreover,we speculated the structure of Si-O-F were existed as atom ratio 33:12:16 on the basic of valence bond theory by Gaussian.Through thermodynamics analysis in the process of extracting potassium from potassium fluoride,in contrast to the traditional alkaline ways in 1000K reaction temperature,the reaction of KAlSi3O8-HF-H2SO4 can proceed spontaneously just below 773K.It proves our technology costs lower energy consumption.Through calculating and analyzing the 19 reactions of KAlSi3O8-HF-H2SO4 system,we drew the ?GT?-T figures and lnK-T figures and concluded that the creation of K3AlF6 were prior to K2SiF6;the creation of AIF3 were prior to KF.The reaction of producing K2SO4 from KF and K2SiF6 were prior;HF and SiF4 were easy to recycle.Therefore between 298K and 450K,the fluorine circulation that HF-fluoride-HF+SiF4 were established.And the equilibrium compositions figures of KAlSi3O8-HF-H2SO4 drawn by HSC Chemistry software.Based on the research,we took advantage of experiments to investigate how temperature influenced the yield of K+.It was concluded that the extraction efficiency increased with increasing reacting temperature at first but dropped in anaphase and the optimum temperature is 348K.In addition,the extraction efficiency increased with increasing leaching temperature and the optimum temperature is 363K.At last,based on the research of low grade lithium ore and the extraction of potassium from potassium feldspar,we comprehensively investigated the fluorine chemical corrosion of silicate minerals,and summarized the fundamental basis of thermodynamics in extraction of silicate minerals and valuable metals using the estimation method of thermodynamics.It also provided the fundamental basis of thermodynamics to fluorine circulation and energy conservation in the extraction of silicate minerals.