DK was founded 135 years ago as Duisburger Kupferhiitte. Its aim at that time was to purchase large amounts of pyrite on the world market for the manufacture of sulphuric acid. After roasting the pyrite, DK recovered nearly every chemical element from the cinders - for example iron, copper, zinc, cadmium and even silver and gold. With changing methods of sulphuric acid manufacture and an extremely complex and expensive process, the then owner, Rio Tinto Zinc, decided to close the plant in 1983. Due to the legal requirement to clean up the site, RTZ installed a trust to continue operations to process the remaining cinders on site. While doing so, more industrial wastes were added to the raw material mix and it became evident that the process could be operated using only industrial wastes.
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