A hydrometallurgical process utilizing an atmospheric
calcium chloride leach to selectively recover from various
metal feed stocks (consisting of elemental metals,
metal oxides,
metal ferrite,
metal hydroxide, metal carbonates,
metal sulfate /
sulfur compounds, and their hydrates, specifically including but not limited to EAF Dust K061)
zinc, lead,
cadmium, silver,
copper and other valuable metals to the exclusion of iron,
magnesium,
halogen salts and other unwanted elements. The process solves the problem of iron and
magnesium leach solution
contamination because iron is unexpectedly converted to
magnetite. The
heavy metals are cemented out of solution using
zinc or other selected dust at a pH of 6 or greater under unique and unexpected conditions, which do not require acid. Simonkolleite /
zinc- oxychloride / zinc-
hydroxide is produced from the purified zinc
chloride complex
pregnant leach solution and is converted directly to high purity active rubber grade 99+% zinc
oxide having
small particle size and
high surface area. The products are metal concentrates suitable for: metal refiner / processors, production of elemental metal, or other conversion processes. The process removes
Arsenic and Fluorides in the feed material. The process also solves the problem of
chloride contamination in the zinc
oxide and prevents heavy
metal contaminants in the hydrometallurgically produced zinc
oxide derived from feed stocks containing chlorides or when chlorides are used to leach the metal bearing feed stocks. In one embodiment,
calcium and / or
magnesium compounds are added to the iron bearing waste to increase the
recovery of zinc and other non-
ferrous metals and to produce an iron bearing flux. The process is
environmentally friendly and fully recycles all streams.