Method for oxidation of pyrite in coal to magnetite and low field magnetic separation thereof

摘要

A method for increasing the magnetization of pyrite-containing pulverized coal comprises heating the coal in an atmosphere of inert gas, desirably nitrogen, containing 3 to 60 torr, preferably 12 to 16 torr, partial pressure of air to a temperature in the range 390° to 455. degree. C., desirably 400° to 410° C., for a time sufficient, preferably 2 minutes to 2 hours, for converting enough pyrite to magnetite to allow separation of at least 50% by weight of the pyrite from the coal in a low-strength magnetic field. The sulfur content of coal treated in accordance with this method can be reduced by subjecting the treated coal to a low-strength magnetic field for moving at least 50% by weight of the pyrite from the coal although a smaller fraction, about 5 to 25%, of the pyrite is actually converted to magnetite.