Removal of Ash Contents from Coal by Flotation.

用浮选法研究了煤中灰分的脱除，该方法与传统浮选法的不同之处在于灰分被浮选而煤仍留在悬浮液中。结果表明：在pH大于11.5的条件下，油酸钠作为捕收剂，经钙活化后，可有效地捕收煤灰分的主要成分——高岭石、地辉石、焦云母和绢云母等粘土矿物。以煤油为捕收剂的压力浮选试验表明，中国大东煤的灰分含量比贺洛奈煤、太黑煤和古尼拉煤的灰分含量明显降低。根据这一结果，选择大东煤作为本次调查的样本。以油酸钠为捕收剂、氯化钙为活化剂对大东煤进行浮选试验，结果表明，在pH为11.5左右时，沉煤（煤精矿）灰分降低，但仍有40 ~ 60%的煤被浮选。然后，对不同药剂进行了抑制煤浮选的试验。淀粉降低了煤的灰分含量。聚氧乙烯辛乙基苯醚（HS-210，由日本石油和脂肪公司生产）对煤的凹陷有轻微的影响。在试验试剂中，聚乙烯醇对煤的选择性抑制作用最强。但不能得到满意的结果，即煤精矿（沉）灰分约为5%，煤的回收率约为80%。

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 %.