高造浆膨润土制备及其性能评价

Preparation and evaluation of high yield sodium-modified calcium base bentonite

安徽铜陵市蕴含地质储量达15000万t的低品位钙基膨润土，蒙脱石平均含量50％～80Voo，现主要用于附加值较低的球团土和铸造土。将这种低品位钙基膨润土先通过悬浮和挤压综合钠化改型工艺，再添加一定量的超高分子量聚丙烯酸钠（PA艮Na）和轻烧氧化镁（Mg（））组成的有机一无机复合增黏剂，以及由小分子水解聚丙烯腈钠盐与腐植酸接枝聚合的专用流变性调节剂（HInPS），制备出了符合水平穿越钻井（HDD）使用要求的高造浆膨润土。分析了钠化工艺和增效添加剂对HDD造浆土的黏度（φ600）、动塑比（YP/PV）、综合流变性能以及成本等的影响，优化得到了具有较好性价比的工艺配方。优化工艺下的HDD造浆土性能φ600 读数大于100dia，YP／PV小于1.5，30min的API滤失量小于15mL。铜陵钙基膨润土改性制备成HDD高造浆膨润土，可将产品附加值提高到1000元/t左右，利润率提高2-3倍，实现了低品位膨润土资源的高附加值利用。

150 million tons of low grade calcium base bentonite are reserved in Tongling of Anhui Province with an average content of montmorillonite between 50% and 80%. The Tongling bentonite is mainly used as pellet soil and molding soil with low added value. In this study, the low grade calcium base bentonite was sodium- modified through suspension and extrusion methods, then added three additives including organic-inorganic mixed viscosifier which is composed of ultrmhigh molecular weight sodium polyacrylate, light-burned magnesia and a homemade rheology modifier HmPS synthesized from humie acid and small molecular weight partially hydrolyzed polyacrylonitrile. High yield bentonite that meets the standard of horizontal directional drilling （HDD） was prepared through the above technical process. After analyzing the effect of sodium modified treatments and additives on apparent viscosity（φ600 ）, ratio of yield point to plastic viscosity （YP/PV）, rheology behavior and the cost of HDD, a more cost efficient technical formulation was achieved. The performances of the product reach the standard： φ600〉100 dia, YP/PV〈1. 5, API filter loss〈E15 mL/30 min. When the calcium base bentonite from Tongling is made into high yield bentonite used in HDD, the added value of the product could reach about 1000 RMB/ton and the profit margin will be 2 - 3 times higher than before. This would he an example of making low grade bentonite into the product with considerable economic benefits.