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针对磷酸盐分解钼酸钙的过程,根据同时平衡原理和质量守恒定律,绘制了25℃时Ca-Mo-P-H2O体系溶解组分的lgC-pH图,以及不同总磷浓度条件下溶液中总钙、总钼的lgC-pH图和钼酸钙稳定区.结果表明,在溶液中总磷浓度一定的条件下,随着pH的增大体系中会依次出现H2MoO4(s)、CaMoO4(s)、Ca5(OH)(PO4)3(s)和Ca(OH)2(s)稳定存在的区域.总磷浓度直接影响到钼酸钙的分解过程,随着总磷浓度的增加,钼酸钙的稳定区域不断减小甚至消失,使得钼酸钙更加易于分解,因此溶液中总钼浓度不断增大,而总钙浓度不断降低;但总磷浓度过高会导致溶液中残留游离含磷离子过高.从热力学角度来看,在钼酸钙分解过程中,添加磷酸盐比碳酸盐更加有利于钼酸钙的分解.
According to the principle of simultaneous equilibrium and conservation of mass, the lgC-pH diagram of the dissolved components of Ca-Mo-P-H2O system at 25 ℃ was plotted for the process of phosphate decomposition of calcium molybdate. Total calcium, total molybdenum lgC-pH and calcium molybdate stable zone.The results show that H2MoO4 (s), CaMoO4 (s) will appear in the system with the increase of pH under the condition of total phosphorus concentration in solution ), Ca5 (OH) (PO4) 3 (s) and Ca (OH) 2 (s) .The total phosphorus concentration directly affected the decomposition process of calcium molybdate.With the increase of total phosphorus concentration, molybdic acid The stable area of calcium is continuously reduced or even disappeared, making calcium molybdate easier to decompose, so the total molybdenum concentration in the solution is increasing, while the total calcium concentration is decreasing. However, when the total phosphorus concentration is too high, residual free phosphorus ions Too high From a thermodynamic point of view, in the decomposition of calcium molybdate, the addition of phosphate is more beneficial than carbonate in the decomposition of calcium molybdate.