New type of potassium deposit: Modal analysis and preparation of potassium carbonate

摘要

A kind of dolomitic mudstone newly found in North China has high amounts of K_2O up to 10w_b% in average, and potassium reserve is at superior scale. Mineral assemblage of the potassium ore indicates a specific and complicated geological environment under which the potassium deposit formed. Modal analysis of the potassium host rock shows that the principal minerals in the ore include microcline, dolomite, and clay minerals such as illite, illite/smectite mixed layer, and kaolinite, attributable to a new type of insoluble potassium deposits in ore genesis. The experiments in this research demonstrated that with sodium carbonate as flux agent, the potassium ore could be decomposed with a proportion as high as 99.4% by calcinations at moderate temperature for no more than 1.5—2.0 h; more than 70% of K_2O in the calcined materials were leached into the liquor, and by acidification reaction of the filter liquor, a large amount of impurities such as Fe~(3+), Ti~(4+), Mn~(2+), Mg~(2+), and Ca~(2+) were removed with precipitation of alumino-silicious colloid residue, which makes it possible to prepare potassium carbonate of electronic grade from the filter liquor, whereas the alumino-silicious residue could be utilized to make mineral polymer, a new type of inorganic construction structural materials. The current research shows that industrial exploitation and comprehensive utilization of this new type of insoluble potassium resource are feasible both in economic benefits and environmental kindness with the fairly clean production process as sketched in this paper.