Washability curve of Senseki is greatly different from that of normal bituminous coal.Floth-flotation is almost meaningless for Senseki, i.e.in the use of usual reagent most of Senseki does not float, otherwise in case of using the most active reagent Senseki of rich ash content floats more easily than that of poor one.If we conduct the de-ashing of Senseki through autoclave method using concent-rated alkali solution, and then hydrochloric acid washing, its residual ash content is more than graphite.
The constitution of residual ash is greatly different from graphite.Graphite consists of SiO
2 and Al
2O
3, while Senseki consists of Fe
2O
3 and CaO in respective ash constitution.The constitution of Senseki resembles closely to that of special ash which has changed the washability curve.
There is very familiar part with polar substances in ash of Senseki, most part of which is largely covered with bitumens carbonized by heating of lava.It might be concluded that the best washing method is Baum jig and table cleaning rather than floth-flotation and others.
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