Prohibitive intercontinental shipping and handling costs compelled Bayer to search for a new centralized location. In 1993, South African chemical company Sentrachem approached Bayer with a proposal to use Sentrachem's partially mothballed site in Newcastle, containing a rubber, carbide, and organic amines plant, for the construction of a brand new chrome-producing facility. Our new plant allows us to remain highly competitive in the pure commodity chrome trading market. The ensuing joint venture chose Foster Wheeler South Africa to design and build the new sodium dichromate plant in the heart of the old facility. The new Chrome International South Africa plant is among the biggest of its kind in the world, capable of producing 70,000 tons of sodium dichromate and 11,000 tons of chromic acid per year.
Chromic acid is used for chrome plating, in the automotive industry, for example.
Through a complex process of solids and liquids processing, chrome is extracted from the ore. The major processes include ore grinding and milling, batch mixing, rotary kiln roasting to convert chromium III to chromium VI, leaching and filtering the chromium VI, precipitation purification to remove vanadium and other impurities, and acidification under high pressure to recover excess sodium. The resulting raw sodium dichromate liquid is either shipped to the chromic acid plant as feedstock, or crystallized and shipped to the final customer. Throughout this state of the art process, by products are recycled back into the process stream, so that virtually no unnecessary waste is created. For example, excess sodium from the acidification process is converted in a calciner to sodium carbonate, one of the key ingredients used in the rotary kiln.