沉淀碳酸钙的溶解性及溶解抑制改性的研究

Dissolution Behavior and Dissolution-inhibition Modification of Precipitated Calcium Carbonate Filler

对一种国产造纸填料级沉淀碳酸钙(PCC)的溶解性及溶解抑制改性进行了初步研究。实验结果表明,PCC在pH值为5.85的蒸馏水及pH值为3.50的硫酸铝溶液中均具有较强的溶解性,在醋酸/醋酸钠缓冲溶液中的溶解性随其pH值的降低而显著增加。硫酸铝、硫酸铝/硅酸钠、硅酸钠/稀盐酸、氯化锌及硅酸钠/氯化锌均可对PCC在pH值为5.85的蒸馏水中的溶解性产生一定的抑制作用。硫酸铝、氯化锌、硅酸钠/稀盐酸可对PCC在pH值为5.95的醋酸/醋酸钠缓冲溶液中的溶解性产生较弱的抑制作用,硅酸钠/氯化锌的溶解抑制作用相对较为显著,滤液钙离子浓度可降低30%左右。当采用两段pH值法将硅酸钠/稀盐酸用于PCC的溶解抑制改性时,改性填料在pH值为3.50的硫酸铝溶液中的溶解性显著降低。

The dissolution behavior of precipitated calcium carbonate filler was analyzed and evaluated, and its dissolution-inhibition modification was preliminarily studied, and the corresponding dissolution-inhibition effects of alum, alum/sodium silicate, sodium silicate/hydrochloric acid, zinc chloride, and sodium silicate/zinc chloride on precipitated calcium carbonate filler were evaluated. The results showed that the dissolution behavior of precipitated calcium carbonate is dependent upon the solution properties, and it dissolves significantly in distilled water with pH value 5.85 and alum solution with pH value 3.50. As for the acetic acid/sodium acetate based buffer solution, the dissolution of precipitated calcium carbonate is more extensive when the pH value decreases. Under the experimental conditions, alum, alum/sodium silicate, sodium silicate/hydrochloric acid, zinc chloride, and sodium silicate/zinc chloride are effective to inhibit the dissolution of precipitated calcium carbonate in distilled water with pH value 5.85, and the pH values of the suspensions decrease. Under the experimental conditions, alum, zinc chloride and sodium silicate/diluted hydrochloric acid are slightly effective in inhibiting the dissolution of precipitated calcium carbonate in buffer solution of acetic acid/acetic sodium with pH value 5.95, and sodium silicate/zinc chloride is relatively more effective in dissolution-inhibition performances, and the calcium ion concentration of the filtrate decreases by approximately 30%. The results also indicated that, sodium silicate/hydrochloric acid is quite effective in dissolution-inhibition of precipitated calcium carbonate in alum solution with pH value 3.50, when the double-pH process is applied in the dissolution-inhibition modification.