In the previous papers, the authors reported that the multi-branched high molecular nonionic surface active agents had good effects on stabiliza-tion of COM.
This paper covers discussion of additive mixing methods for assuring stability of COM.
First, a COM sample was prepared by using Bank coal as a typical bituminous coal in order to evaluate a homomixer and a propeller in mixing effect. As a result, it was found that stabilization of COM would require sufficient mixing by homomixer. The same COM, diluted with A heavy oil, was subjected to microscopical examination. It showed that coal particles in an unstable COM would remarkably coagulate but those in a COM sufficiently mixed with an additive would not. This phenomenon was regarded as a COM stabilizing mechanism.
Then, for finding an appropriate mixing rate, the abovementioned sample and COM with Beluga coal as a typical lignite were subjected to a continuous mixing (1 ton/hr) test with a line mixer. This test found that stabilization of COM would be promoted as the peripheral velocity of the agitator was higher, or would need powerful agitation (more than 15 m/sec of peripheral velocity, more than 106kg·m/m3 of mixing energy).
In order to lower the required mixing energy, the authors designed and discussed a new method that an additive was diluted with heavy oil (part of COM materials) before mixing it into COM. This heavy oil dilution method provided much higher mixing efficiency, or yielded far more stable COM than the direct addition method.
