Abstract: Silicate-based composition particles are rapidly and completely expanded to form an expanded, cellular particulate aggregate of maximum density in short periods of time at particle temperatures which are comparatively low, that is, 100.degree. C., compared to existing systems by the utilization of infrared heat sources, either gas or electric, to heat the silicate particles. The use of infrared energy operates in a surprisingly advantageous fashion when the expansion process is carried out on or in the presence of a surface having the capacity to act as a thermal mirror or absorber-reflector of the infrared radiation to make maximum utilization of the radiant energy by the creation of a radiation trap. Carbonaceous materials are preferred for producing such entrapment. A further significant aspect is the discovery of a time-radiation dependency.

Abstract: An electrochemical process for rapidly achieving the recovery of precious metals such as gold and silver from their ores. The ore is formed into a slurry and combined with an electrolyte such as sodium cyanide and an alkaline substance such as sodium hydroxide to increase alkalinity to at least 0.01 equiv./liter. The ore slurry and electrolyte are placed in a recovery apparatus in direct touching contact with closely spaced large area anodic and cathodic electrodes, preferably spaced apart by a distance of about 1 cm. or less. A voltage is applied to the electrodes to produce a current density in the slurry of about 10 to 20 amperes per square meter, and the slurry is agitated to provide diffusion of the ore grains into electrical contact with the electrodes to promote precious metal dissolution.

Abstract: An electrochemical process of the type for recovering precious metals such as gold and silver from their ores by adding to a slurry of the ore a cyanide complexing agent such as sodium cyanide and by electrolytically recovering the precious metal. The process is characterized by the use of small quantities, e.g., 50 milligrams per liter, of a water soluble electroconductive cationic resin, preferably polyvinylbenzyltri-methylammoniumchloride sold under the name ECR-34 by Dow Chemical Company of Midland, Michigan as an aqueous solution containing 33.7% of solids. The use of such a resin increases the amount of precious metals recovered from the ore per unit of time, improves the degree of recoverability, and improves the quality of the recovered metal.

Abstract: A desirable metal such as gold in a low grade ore has its concentration increased by electro-kinetically separating gangue from other components in the ore to form a concentrate. Separation is effected by inducing movement of externally conductive particles upwardly and radially outwardly over the walls of a container enclosing a dielectric liquid within which the ore is initially contained. An electric field is established for this purpose between the container walls and an electrode positioned above the surface of the dielectric liquid.