Study On A New Technology Of Resource Utilization Of Phosphorus Potassium Associated Minerals

Nitrogen,phosphorus and potassium are the three essential nutrients for crop growth.Our country’s chemical fertilizer industry is limited by resources,the phenomenon of excess nitrogen,little phosphorus and potassium deficiency is very serious and nearly 50%of the total potash used in agriculture still need to import from other countries,which greatly restricts the continued rapid development of my country’s agriculture.At present,my country’s phosphate resources are very rich,but there are few high-quality mines,shortage of soluble potassium resources,but my country’s phosphorus-potassium associated ore is rich,compared to alone phosphorus or potassium,give full play to the natural phosphorus symbiosis of this mine.Economically developed this mineral resources,developing the chemical fertilizer production methods in accordance with my country,which is important for the comprehensive utilization of phosphorus-potassium associated minerals in my country.This paper systematically studies the new technology of resource utilization of phosphorus-potassium associated minerals,and proposes a new process route for the preparation of silicon-calcium-potassium compound fertilizers:1.The use of recycled high-temperature hydrochloric acid to hydrolyze the slurry-like phosphorus-potassium associated minerals to efficiently extract phosphorus;2.Use acid Calcium chloride produced by slag solution and acid leaching is thermally decomposed to extract soluble potassium salt under superheated steam atmosphere,and hydrochloric acid is generated at the same time to realize chlorine cycle;3.Use the extracted potassium chloride and high-temperature roasting residue to mix and grind,and granulate,to prepare silicon-calcium-potassium compound fertilizer.In this paper,according to the above process route,the whole process of the new technology for resource utilization of phosphorus-potassium associated minerals was studied,and silicon-calcium-potassium compound fertilizer was successfully prepared.The process of decomposition of phosphorus-potassium associated ore by high-temperature hydrochloric acid was studied,the reaction process of high-temperature decomposition of acid-decomposing residue in superheated steam atmosphere was discussed,and the reaction mechanism of calcium chloride decomposition of potassium feldspar in superheated steam atmosphere was discussed.The research is carried out,which lays a theoretical foundation for the development and application of phosphorus-potassium associated minerals.In this paper,the optimal process conditions for acid hydrolysis of phosphorus-potassium associated minerals with high temperature hydrochloric acid were obtained:initial liquid-solid ratio 2,hydrochloric acid vapor temperature 280℃,hydrochloric acid concentration 20%,particle size of phosphorus-potassium associated minerals 75-125μm,stirring speed 300 rpm,the reaction time is 60 min,under this condition,the extraction rate of phosphorus can reach more than 96%.the dynamic experience equation obtained the acid solution process is obtained.The shrinking core model is used to fit the reaction process,which is controlled by external diffusion,and the kinetic empirical equation for the acid hydrolysis process is obtained.The solvent extraction method is used to extract and purify the leachate,and the optimal process conditions for extraction and purification are obtained:the extractant is a mixed alcohol of n-isoamyl alcohol with a volume ratio of 2:1,the number of extraction stages is 6,and the number of back-extraction stages is 4.This The extraction rate of phosphoric acid can reach above 92%.In addition,the solvent extraction method was used to extract and purify the leachate,and the optimal process conditions for extraction and purification were obtained:the extraction agent was a mixed alcohol of n-isoamyl alcohol with a volume ratio of 2:1,the number of extraction stages was 6,and the number of back-extraction stages was 4,the extraction rate of phosphoric acid can reach more than 92%.The research on high-temperature roasting and decomposition using acidolysis residue and calcium chloride as raw materials was carried out.During the reaction process,superheated steam was introduced to build a specific atmosphere to ensured that the potassium feldspar in the acid hydrolysis residue can be decomposed and extracted,and at the same time,the chlorine in the calcium chloride generates high-temperature hydrochloric acid vapor to be circulated,and finally the silicon-calcium-potassium compound fertilizer that can be used for agricultural production is prepared.The optimum process conditions for high-temperature decomposition and dechlorination of acidolysis residues are as follows:the reaction temperature is 900℃,the mass ratio of Ca Cl₂and acidolysis residues is 1.5,the steam volume is 3 m L/min,and the reaction time is 150 min.Under these conditions,the chlorine removal rate is can reach more than 96%.The shrinking core model is used to fit the reaction process,which is controlled by internal diffusion,and the kinetic empirical equation of the pyrolysis process is obtained.Thermodynamic analysis and reaction product analysis showed that under the synergistic effect of superheated steam and calcium chloride,the potassium feldspar in the acid hydrolysis residue would decompose into soluble potassium chloride and anorthite at the reaction temperature of 800℃.In addition,the reaction process is also accompanied by the hydrolysis reaction of calcium chloride to generate high-temperature hydrochloric acid and wollastonite.Based on the extraction rate of potassium,the process of preparing silicon-calcium-potassium compound fertilizer was optimized.Combined with the process conditions of high-temperature decomposition and dechlorination,the optimal process conditions for the preparation of compound fertilizer were finally obtained:reaction temperature 800°C,mass ratio 1.5,steam volume 3 m L/min,and reaction time 150 min.Under this condition,the removal rate of chlorine can reach 88%,the extraction rate of potassium can reach 94%,and 81.85%hydrochloric acid can be recycled.The recycled potassium chloride and the roasting residue are mixed,ground,and granulated to obtain a silicon-calcium-potassium compound fertilizer product.