A process for the recovery of copper from its ores by conventional procedures requiring heat in which the source of heat is microwave energy. The microwave energy is used to selectively heat the copper compounds, such as sulfidic and oxidic compounds, in the ore, as respects the gangue, to convert the compounds into other compounds, such as oxides and chlorides, from which copper is more readily recoverable.

A process for the recovery of nickel, cobalt or manganese from their oxides or silicates wherein such process, which requires the application of heat, is improved by utilizing microwave energy as the source of heat. The microwave energy may be utilized to cause the reduction of these values enabling such reduced values to then be recovered by conventional leaching processes. The microwave energy may also be used in conjunction with the chlorination of such values to produce their chlorides which are subsequently separated from the gangue and then processed by conventional means to obtain the metal values.

A process for the recovery of molybdenum and rhenium from their sulfide ores which comprises subjecting the ores to microwave energy in the presence of oxygen to selectively heat the sulfides to convert them to oxides, and recovering the formed oxides. Alternatively, the sulfides in the ore are selectively heated with microwave energy in the presence of chlorine to convert them to the corresponding chlorides, and the metals recovered from the chlorides.

A method and apparatus for desulfurizing coal is provided. The method involves combining non-pulverized sulfur containing coal with an adsorbent material, such as aluminum oxide, in a vessel, irradiating the coal/adsorbent combination with microwave energy sufficient to subject the coal/adsorbent combination to a temperature of between about 250.degree. F. and about 650.degree. F. for a period of time sufficient to cause the release of sulfur from the coal as a gas. A magnetic field may be provided around the vessel to concentrate the microwave energy being introduced into the vessel within the vicinity of the magnetic field to enhance the release of the sulfur from the coal. The adsorbent is admixed with the coal during and after the heating step to adsorb some of the gaseous sulfur liberated from the coal. The apparatus capable of performing this method includes a heating section, a mixing section, a screening section and a gas treatment section. The sulfur containing gas liberated from the coal is vacuumed from the heating section into the gas treatment section where it is subjected to processing into sulfuric acid. The mixing section performs the admixing of the coal/adsorbent and the screening section separates the adsorbent from the coal and includes an apparatus for directing the coal or the adsorbent to individual receiving and/or conveying receptacles.

The process of demetalization and desulphuration of a mixture of carbonaceous material in an acid medium subjecting the mixture to the influence of wave energy in the microwave range, recovering, afterwards, the sulphur and separating the treated material from the rich in metal liquors.