添加剂对KAlSi_3O_8-CaSO_4-CaCO_3体系反应表观活化能的影响

The effects of the addition of four types of fusing agents on the apparent activation energy of the KAlSi_3O_8-CaSO_4-CaCO_3 system

首先测定了KAlSi3O8-CaSO4-CaCO3体系在不同焙烧条件下钾长石转化成可溶性氧化钾的转化率,进而通过模拟计算表明:KAlSi3O8-CaSO4-CaCO3体系的固相扩散动力学过程符合金斯特林格动力学方程,反应表观活化能Ea为128.92kJ/mol。并着重考察了4种添加剂Na2SO4、Na2SO3、NaCl和NaF对KAlSi3O8-CaSO4-CaCO3体系的影响,结果表明:向体系中分别加入占反应物总质量3%的Na2SO4、Na2SO3、NaCl和1%的NaF后,体系的反应表观活化能Ea从原来的128.92kJ/mol依次下降至87.15、98.71、117.38和126.14kJ/mol,这表明4种添加剂中Na2SO4的效果最好,它能较大程度上降低反应表观活化能,从而降低反应温度和提高固相反应速率。

K-feldspar （KAlSi3O8） is a major potassic aluminosilicate mineral in nature, and its total reserves are up to 4.641 billion tons in China. Up till now, however, there still exist many difficulties in using this resource directly as potash fertilizer in agriculture due to its high insolubility. In order to decrease the calcination temperature and shorten the calcination time for transforming K-feldspar into soluble potash salt and hence reducing the production costs, this paper has discussed the influences of the addition of four types of fusing agents on the KAlSi3O8-CaSO4-CaCO3 system and selected the most favorable fusing agents. The transformation ratios from K-feldspar mineral to soluble K2O in the KAlSi3O8-CaSO4-CaCO3 system under different calcination conditions were detected systematically. A simulation calculation on such a basis demonstrated that the solid diffusion dynamical process in this reaction was in accordance with the Ginstling dynamic equation, with its apparent activation energy Ea being 128.92 kJ/mol. Four types of fusing agents, namely Na2SO4, Na2SO3, NaCl and NaF, were added into this reaction system respectively by 3%, 3%, 3% and 1% of the total mass of reactant, and the value of the apparent activation energy Ea was decreased from 128.92 to 87.15, 98.71, 117.38 and 126.14 kJ/mol in turn. It is thus shown that Na2SO4 may be the most favorable fusing agent, which can reduce apparent activation energy Ea, decrease reaction temperature effectively and speed up solid diffusion velocity in the KAlSi3O8_CaSO4-CaCO3 system.