钙基膨润土钠化工艺过程及其对矿浆黏度影响研究

Sodium Modification Process of Calcium Bentonite and Its Effect on Pulp Viscosity

为解决膨润土钠化过程中矿浆变黏的问题,系统研究了碳酸钠用量、矿浆浓度以及分散剂对钠化效果及矿浆黏度的影响,探讨了降低矿浆浓度和加分散剂的作用机理。结果表明:当采用降低矿浆浓度的方法时,“卡房”结构明显减少,矿浆变黏的问题得到改善,但同时会增大矿浆量,增加处理难度;当采用添加分散剂焦磷酸钠的方法时,磷酸根离子吸附在蒙脱石的正电性边缘,可以增加蒙脱石之间的排斥力,从而降低矿浆的黏度,有利于提高钠化效果。当焦磷酸钠用量为0.5%(质量分数)、矿浆浓度为5%(质量分数)、碳酸钠用量为5%(质量分数)时可制得高品质的钠基膨润土,与未钠化相比,在该条件下钠化1.5 h,得到的钠基膨润土胶质价由95 mL/15 g提高至975 mL/15 g,膨胀指数由8 mL/2 g提高至25 mL/2 g。

In order to solve the problem of pulp viscosity in the modification process of sodium bentonite, the effects of sodium carbonate dosage, pulp concentration and dispersant on the effect of sodium modification and pulp viscosity were systematically studied, and the mechanism of reducing pulp concentration and adding dispersant were discussed. It is found that by reducing the pulp concentration, the “house-of-cards” structure by edge-to-edge and edge-to-face contact is obviously reduced, and the problem of pulp viscosity is improved, but the pulp quantity and the treatment difficulty increase at the same time. By adding dispersant sodium pyrophosphate, phosphate ions are adsorbed on the positive edge of montmorillonite, which increases the repulsive force between montmorillonites and reduces the viscosity of pulp, and improves the sodium effect. Through systematic experiments, high quality sodium bentonite is prepared with 0.5%(mass fraction) sodium pyrophosphate, 5%(mass fraction) pulp concentration and 5%(mass fraction) sodium carbonate. In this condition, the swelling index and colloidal value of bentonite have been greatly improved, the colloid value of sodium bentonite increases from 95 mL/15 g to 975 mL/15 g, and the swelling index increases from 8 mL/2 g to 25 mL/2 g after 1.5 h sodium modification.