Research On Potassium Extraction From Potash Feldspar With Acids

In our country it is very lack of potassium mineral resources, so the rational use of non-water-soluble potassium mineral resources especially the potash feldspar has a very important economic significance. This paper mainly studies research about potassium extraction from potash feldspar with acids at the low temperature, using the pure chemical reagents to imitate phosphorite for potassium extraction from potash feldspar with acids, in the case of exclusion of reactivity,metallogenic reason of phosphorite etc on leads to the results of differences, study the universal applicability of the phosphorite, conducted a preliminary study on the mechanism and kinetics of the process of extracting potassium from potash feldspar, the two methods of the potassium content analysis of potash feldspar system are compared, instead of sulfuric acid as the acid hydrolyzate, and K-feldspar reaction to sulfuric acid urea,the system process was optimized.Through the use of pure chemical reagents and potash feldspar reaction, analysis of the effect about various components on the dissolution rates of potassium, the mechanism of the process is preliminary discussed, the experimental results:the order of descending of various factors on the potassium dissolution rates is:the quality of calcium fluoride, mass ratio of magnesium oxide and calcium oxide, the quality of tricalcium phosphate, more optimized composition ratio is:K-feldspar: phosphorite0.8:1,phosphorite:tricalcium phosphate:calcium fluoride1:0.5:1, the mass ratio of magnesium oxide and calcium oxide is1:1. Within the scope of the common fluoride content of phosphorite, the dissolution rate of potassium showing monotone increasing trend with increasing fluoride content.Through the discussion of the universality of phosphorite it can obtain that:the mechanism of potassium extraction from potash feldspar can be divided into two steps:the first step is the reaction of phosphorite and sulfuric acid which produces hydrofluoric acid and then hydrofluoric acid destroy potassium feldspar’s structural; the second step is the replacement reaction that calcium and magnesium ions into the potash feldspar internal replaces potassium ions. Dynamics analysis shows that:use pure reagent or phosphorite for potassium extraction from potash feldspar with acids the dynamics analysis is consistent, neither a simple physical control process or chemical reaction control, but belongs to the solid-phase diffusion-controlled process.Given the special nature of the process, the comparative experiment is conducted for the applicability of such a system of potassium content analysis,through the analysis with two methods of the samples, the results show that the measured results of the sodium tetraphenylborate gravimetric method is higher than the volumetric method’s, the sodium tetraphenylborate gravimetric method is more accurate, the gap between the parallel experiment is very small. The addition amount of EDTA has a bigger impact on the analysis results of gravimetric method and volumetric method, if the addition amount of EDTA is less than normal gravimetric method, it will cause larger experimental results, when the dissolution rate is higher (more than95%), if the addition amount of EDTA is insufficient, perhaps even the dissolution rate is greater than100%, if the addition amount of EDTA is not enough for volumetric method, it can lead to the end color return to the previous color after a period of time and then the analysis is failure,Based on the status of the acid process and mechanism discussion of the system, starting from the point of view of energy saving and environmental protection, through the optimization of the process conditions of the urea solution of sulfuric acid and potassium feldspar reaction, reaction time, reaction temperature, amount of sulfuric acid and the mass fraction of urea, mole ratio of urea and sulfuric acid were investigated to the influence potassium dissolution rate, access to the optimal process conditions,compared with the system of potash feldspar-phosphorite-sulfuric acid, though the dissolution rate of the system of potash feldspar-phosphorite-urea sulfuric acid decreased, it has some advantages such as:the reaction of sulfuric acid and phosphorite became ease, the emission of fluorine, content environmental pollution and the energy consumption are reduced.