Abstract: Complex ores of the precious metals which also contain iron spinels and similar compounds are assayed and their precious metals content is extracted by subjecting the ores or concentrates thereof together with an iron-embrittling agent to a pyrometallurgical process which reduces at least a major portion of the iron compounds to liquid metallic iron. The liquid iron serves as a collector metal for the precious metals and, after cooling, the iron is brittle and easily comminuted and can be separated from the precious metals through use of either an electrolytic process or a selective chemical dissolution of the iron and other base metals leaving the precious metals available for analysis and recovery.

Abstract: Particulate mixtures of non-magnetic or paramagnetic materials are separated by selectively coating the surfaces of a component or components of the mixture with a magnetic fluid. Thereafter, the particulate mixture is subjected to a magnetic separation yielding a magnetic fluid-coated fraction and a non-magnetic fraction. The process is especially useful in mineral beneficiation wherein a mineral concentrate is recovered from its ore.