改善碱回收白泥粒径分布的研究

粒径分布宽及小粒径组分多是碱回收白泥作造纸填料时应用性能差的主要原因．在实验中以碱回收生产线的生石灰和绿液为基本原料，通过优化碱回收白泥制备的主要工艺参数获得自制白泥，将其与商品轻质碳酸钙（商品PCC）和工厂白泥进行微观性能和应用性能的对比．研究结果表明：当消化反应转速为200r／min、消化时间为15min、苛化反应转速为200r／min、绿液在消化反应与苛化反应中的分配比例为1：2时，可制备出粒径分布在2～25μm范围、中位粒径为7．93pm、颗粒规整的白泥．滤水性能和留着性能方面，自制白泥好于工厂白泥，与商品PCC的相当．同样用量条件下，自制白泥和商品PCC都比工厂白泥赋予纸页更高的白度和不透明度，但因灰分含量高，纸页强度有所降低．

Improving the Particle Size Distribution of White Sludge from Alkali Recovery

Wide particle size distribution and large amount of small particle size components were the main reasons for poor application performance of white sludge from alkali recovery as paper fillers. In this research, quicklime and green liquor from an alkali recovery line were used as the raw materials for the preparation of white sludge, and the process parameters for the preparation were investigated;the micro-properties and application performance of the laboratory-made white sludge, a white sludge from alkali recovery line, and a commercial precipitated calcium carbonate （PCC）were compared. The results showed that uniform and integrated white sludge with 2μm to 25μm particle size distribution and 7.93μm median particle size could be obtained, when the stirring speed of slaking was 200 r/min, slaking time 15 minutes, stirring speed of causticizing 200 r/min, and the ratio of green liquor in slaking and causticizing reactions was 1 ： 2. The white sludge ob- tained in this research has better drainability and retention, and can provide paper with higher degree of brightness and opac- ity, though inevitably higher filler retention will impair paper strength.