苛化法制备亚微米纺锤形碳酸钙联产氢氧化钠

为了解决制碱白泥所带来的二次污染问题,在苛化法的基础上改进出一种新工艺。该工艺在制碱过程中不再副产白泥,而是将原料中的钙转化生成高附加值的亚微米纺锤形特种碳酸钙,并联产高含量的液体氢氧化钠。研究了消化与苛化工艺条件对碳酸钙粒径和氢氧化钠含量的影响,采用扫描电镜(SEM)对样品形貌做了表征。结果表明:在柠檬酸钠添加量为1%(质量分数)、消化水温为84℃、闷灰时间为40min、加料时间为20min的条件下,制备出颗粒短径为180nm、粒径分布为150~200nm、长径比为3的亚微米纺锤形碳酸钙,并联产出高含量的液体氢氧化钠。

Preparation of sub-micron spindle-shaped calcium carbonate and sodium hydroxide co-production by causticizing method

A new process was improved on the basis of causticizing method in order to solve the secondary pollution problem caused by alkali white mud.The calcium in the raw material was converted into a high value-added sub-micron spindle-shaped special calcium carbonate,a high content of liquid sodium hydroxide was produced in parallel and white mud was no longer produced in the process of alkali production by the new process.The influence of the conditions of digestion and causticization on the particle size of calcium carbonate and the content of sodium hydroxide were studied.The morphology of the sample was characterized by scanning electron microscope（SEM）.Results showed that under the condition that the adding amount of sodium citrate was 1%（mass fraction）,the temperature of digested water was 84 ℃,the time of smoldering was 40 min and the feeding time was 20 min,a submicron spindle-shaped calcium carbonate with short diameter of 180 nm,particle size distribution of 150~200 nm and length-diameter ratio of 3 was prepared,and a high content of liquid sodium hydroxide was produced in parallel.