The recovery of gold from its ores

This document provides a systematic examination of the occurrence, properties, production, and metallurgical recovery of gold from its ores, with particular reference to early twentieth‑century practice. It first outlines the geological modes of occurrence of native gold and gold tellurides, emphasizing their associations with quartz, sulfides (notably pyrite, sphalerite, and others), and secondary oxidation products in both lode and alluvial environments. The physical and chemical properties of gold relevant to its extraction—such as malleability, specific gravity, alloying behavior, and solubility in cyanide and chloride media—are reviewed, followed by a discussion of industrial and monetary uses, including its critical role in currency reserves, dentistry, and specialized alloys. The document then presents historical and contemporary statistics on world and U.S. gold production, contextualizing gold supply in relation to monetary demand and industrial consumption. The principal unit operations of gold recovery are described and compared, with detailed treatment of amalgamation, cyanidation, gravity concentration, and flotation, including process principles, flowsheets, typical losses, and plant configurations. Attention is given to metallurgical testing, plant design, operating and capital costs, reagent use, and treatment of flotation concentrates. Overall, the work serves as a technical guide to gold milling practice and process selection under the economic and technological conditions of the period.