Study On The Decomposition Of Potassium Feldspar By Sub-molten Salt And Ion Exchange Method

Water-soluble potassium resources are very scarce in China, while the reserve of non-water-soluble potassium resources such as potassium feldspar is extremely abundant.But because the chemical property of potassium feldspar is so stable that it can hardly be decomposed. It is difficult to apply simple physical or chemical methods to extract potassium. Therefore, trying to explore new ways of potassium feldspar activation has important economic value. In addition to containing K2 O, potassium feldspar still contains a large amount of silicon aluminum resources. It is technically feasible that the manufacture of potash fertilizer separates from the use of silica alumina resources, but economically unreasonable. Therefore, in addition to realizing the extracting of potassium from potassium feldspar, the rational use of aluminum silicate resources is another important topic. It is an ideal choice to synthesize aluminum silicate zeolite to considering from improving the value of products. A novel process was developed for the decomposition of potassium feldspar using KOH sub-molten salt to prepare W zeolite. The effects of activation temperature, alkali-to-ore mass ratio, alkali concentration and crystallization conditions on the morphology and structure of products were discussed in detail. The W zeolite can be synthesized under the optimal reaction conditions: initial KOH-to-ore mass ratio 3:1, alkali concentration 75%, activation temperature160 ℃, molar ratio of crystallization system 20K2O:12SiO2:1Al2O3:620H2O, aging temperature 25℃, aging time3 h, crystallization temperature 130℃, crystallization time 24 h. Adding the quality as 1wt%of crystal seeds(on the basis of the quality of dry basis) to the crystallization system can shorten the crystallization time to 3h. The mother liquor after preparing W zeolite can be recycled as reaction medium of the decomposition of potassium feldspar for the next cycle.The decomposition of potassium feldspar by ion exchange method under hydrothermal condition was studied. NaCl, Na2CO3, CaCl2 and NH4 Cl were used as activators. The contents of K+ in the solution were measured. The influences of temperature, time and activators concentration on the decomposition of potassium feldspar were discussed. With the help of orthogonal experiment, the best combination was found out: activator Na2CO3,temperature 190℃, the concentration of Na2CO3 25%, time 6h, the particle size of ore75μm. The extracting ratio of potassium reached 13.14%. The experiment indicated that shrinking model can be used to describe the process of decomposition of potassiumfeldspar by ion exchange method under hydrothermal condition. The intraparticle diffusion was the control step in the initiation of the reaction and the process was controlled by chemical reaction in later stage.