Utilization of Low-rank Brown Coals with Pollution Control

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In this project, the following researches have been done.(1) Removal of Heavy Metals from Waste Waters by Calcium-loaded CoalTwo types of brown coal, oxyhumolite and peat were studied with respect to their ability to remove heavy metals from waste water. The results showed that the calcium loaded from these materials can be effectively used for heavy metal extraction by ion exchange with calcium. The studied materials have a similar selectivity for a given metal. From the practical point of view, however, the calcium-loaded coal can be recommended : oxyhumolite partially disintegrated in the contact with the solution and the utilization of peat is economically less favorable. The proposed method can be recommended for concentrations of metals less than 10 mM.(2) Utilization of Coal Ash from FBC Boilers as Road Base MaterialThe disposal of fluidized-bed combustion ash is increasingly difficult, and therefore costlier, because of tighter legislation on waste management. It would be useful if ash from fluidized-bed combustion could be processed into road base material. A simple and low-cost road base material production process has, therefore, been developed where the ash is mixed with water, molded, steamed, aged and crushed into small pieces. The conditions required to yield optimum products and the paving test results were discussed.(3) Liquefaction of Low-Rank Coal using Supercritical WaterThe liquefaction of low-rank coal with supercritical water has been studied using a semi-batch microreactor. Liquids yield to 41wt% is attained in less than 7 min. Subsequent gasification of residue takes place. ^2D-n.m.r. spectral analysis of liquids products in supercritical and the results of mass balance suggests that both hydrolysis and condensation reactions contribute to oxygen removal during supercritical water liquefaction of coal.