Prevention of coal freezing by means of acetates

Abstract

With a view to finding new reagents for preventing the freezing of coal in winter, the acetates of sodium, potassium, calcium, and magnesium are studied, as well as a mixture of calcium and magnesium acetate. Attention focuses on their physicochemical characteristics, methods of preparation and of introduction in coal concentrate, and their influence on freezing. Metal acetates are safe for most surfaces, including concrete, metal, and wood. They are biodegradable under the action of bacteria. They are also nontoxic and minimally corrosive. The research shows that acetates match — and in some cases surpass — metal chlorides in their ability to prevent the freezing of coal. It is found that the freezing point depends on the method by which the salt is formed in the coal. In particular, if gas is formed as a result of salt formation, the freezing point is lowered by 1.2°C. The results show that the freezing point is best reduced by means of mixed calcium–magnesium acetate, as a result of a synergetic effect.