Method to determine the decrepitation index of South African manganese ores when heating in a rotary kiln

Manganese ores are the major raw materials utilized in the production of manganese ferroalloys. Decrepitation, which is described as the breakage or disintegration of the ore particles upon heating in a rotary kiln, is an important quality parameter of these ores. The Decrepitation Index (DI), the parameter used to describe the extent of decrepitation, is described as the ratio of the mass of particles <6 mm after pre-heating to the total mass of the sample. After a rigorous review of literature, it was found that the procedure to determine DI of manganese ores in rotary kiln does not exist. This necessitated the development of a method to determine the DI of manganese ores when pre-heated in a rotary kiln. The method was developed through the following steps • The method from the ISO standard 8371 to determine the DI of iron ores in a muffle furnace was studied and the method developed was based on the method. • A literature review on the decrepitation of ores and the factors that cause fines generation during a tumbling test. The method developed can be used to investigate the effect of temperature, rotational speed and size range on the DI of South African manganese ores.