Abstract: The invention relates to a method and apparatus for extracting gold from gold ore. The apparatus and process save capital and operating costs in the extracting of gold from gold ore and include comminution and leaching of the ore, and more particularly the apparatus and process reduce the costs for the ore grinding, and make a fine ore grinding superfluous without having to accept a reduction in the gold yield during leaching. The gold ore is subjected to a product bed stressing and interparticle crushing in the nip of a high-pressure roller press before being leached and the product that has been product-bed-comminuted and subjected to interparticle crushing and the product agglomerates thereby formed are piled on a heap that is sprayed with a lixivium.

Abstract: A method for processing a sulfidic zinc source to recover metallic zinc wherein the source is leached with an electrolysis cell acid, the leaching product is separated into a liquor and a primary leaching residue, followed by drying and smelting of the dried leaching residue. The improvements of the present invention are directed primarily to the treatment of the liquor recovered from the leaching stage, and involve crystallizing out Fe.sup.2+ from the liquor as a ferrous sulfate hydrate in a crystallization stage, separating the filtrate from the crystallization stage in a first separation stage to produce a filtrate and a residue, neutralizing and oxidizing the separated filtrate from the crystallization stage to precipitate the remaining Fe.sup.2+ in a precipitation stage, separating the filtrate from the precipitation stage in a second separation stage and purifying the separated filtrate from the second separation stage before passing it to the electrolysis cell.

Abstract: Method and apparatus for leaching and precipitating metal values from a metal bearing solid in which the solid is simultaneously crushed and acid leached in a vibratory grinding mill, and the pulp thus produced is subjected to a simultaneous leaching and precipitation step in a vibratory reactor into which there is introduced a metal which is higher in the electromotive series than the metal to be recovered, together with controlled amounts of water.