Removal of Ash Contents from Coal by Flotation.

采用浮选法脱除煤中灰分，与传统浮选方法不同的是，煤中灰分主要由高岭石、地开石、叶绿泥石和绢云母等粘土矿物组成。研究结果表明：在pH高于11.5时，油酸钠作捕收剂对煤中灰分的主要成分高岭石、地开石、叶绿泥石和绢云母进行了有效的浮选。用煤油作捕收剂的加压浮选试验表明，中国大同煤的灰分比霍罗奈煤、太黑约煤和古尼拉煤的灰分降低幅度更大。采用油酸钠为捕收剂、氯化钙为活化剂的大同煤浮选试验表明，在pH值为11.5左右时，沉煤灰分降低，但浮选煤的比例为40%~60%，并考察了不同药剂对煤浮选的抑制作用。淀粉和煤一样降低了灰分含量。聚氧乙烯辛基苯醚(HS-210，日本油脂公司生产)对煤的抑制率影响不大。在所测试的试剂中，聚乙烯醇对煤显示出最选择性的抑制作用。但精煤(沉渣)灰分在5%左右，煤回收率在80%左右，效果并不理想。

The removal of ash contents from coal has been investigated by a flotation method which differs from a conventional flotation method in that ash contents are floated and coal is remained in the suspension.The results obtained are as follows :Clay minerals such as kaolinite, dickite, pyrophillite and sericite which are main constituents of ash contents of coal could be effectively floated by sodium oleate as a collector at pH above 11.5 after calcium activation.Pressure flotation experiments using kerosine as a collector showed that ash content of Dah Torng coal from China was more significantly decreased than those of Horonai, Taiheiyo and Goonyella coals. From this result, Dah Torng coal was chosen as a sample of this investigation.Flotation experiments of Dah Torng coal using sodium oleate as a collector and calcium chloride as an activator showed that ash content of sink(coal concentrate) decreased at pH about 11.5, but 40-60 % of coal was floated.Then, various reagents were tested in order to depress flotation of coal. Starch depressed ash contents as well as coal. Polyoxyethyleneoctylphenylether (HS-210, manufactured by Nippon Oil & Fats Co.,) had a slight effect on coal depression. Polyvinyl alcohol showed the most selective depressing action for coal among reagents tested in this investigation. But, satisfactory result could not be obtained, i.e., ash content of coal concentrate(sink) was about 5 % and coal recovery was about 80 %.