ALKALINE LEACHING; SODIUM HYDROXIDE

The document is a compiled bibliography of patents related to alkaline leaching processes in hydrometallurgy, with no explicit abstract or summary section. It summarizes U.S., British, Canadian, and German patents dealing primarily with alkaline leaching of bauxite for alumina production (including Bayer process improvements, pretreatment of goethitic bauxites, desilication, impurity removal, and red mud treatment), as well as extraction of alumina from alunite. Additional entries describe alkaline processes for other ores and products, such as chromite to chromate, copper and gold recovery from sulfide ores using ammoniacal systems, tungsten extraction from scheelite/wolframite with ammonium carbonate, and selective impurity removal from molybdenite concentrates. For each patent, the document lists the core process steps, operational conditions in brief, claimed advantages (e.g., higher yield, reduced scale, minimized reagent loss, improved impurity removal), inventors, assignees, dates, and priority data. Collectively, it serves as a reference source on technological developments in alkaline leaching and related solution purification methods around the mid‑1970s.