Nyrstar Zinc Refinery
Zinc refinery free of solid waste
Nyrstar operates a zinc refinery in Budel-Dorplein in the Netherlands where 450 employees produce 260,000 tonnes of zinc per year. The subsidiary is owned 100% by Nyrstar, the world's biggest producer of zinc and a leading company in lead, silver, gold and copper. The production process produces two bleed streams that require treatment: a weak acid from the wash tower and an electrolyses bleed.
Traditionally, acidic streams are treated using lime to neutralise acid and to precipitate metals. This conventional treatment created a large amount of contaminated gypsum that was stored around the smelter. In over a hundred years of zinc refining the contaminated groundwater underneath the plant had become polluted with sulphate and heavy metals like zinc and cadmium. A geohydrological containment system (GHS) was installed to avoid further spreading of the pollution.
In 1992, Paques designed and built the first full-scale SULFATEQ™ to treat the water from the GHS with a design flow of 230 m3/h.
From July 2000, legislation prohibited further production of solid residues at the site. This meant that an alternative had to be found for the lime neutralisation of acid bleeds from the gas treatment and zinc electrolysis.
Various alternative water treatment processes were studied to find a process that avoids the production of solid or liquid waste. A second SULFATEQ™ installation was commissioned to neutralise the acid with calcine, and to convert the dissolved zinc sulphate into zinc sulphide and elemental sulphur, which are recycled to the roaster. As a result, the site does not produce solid waste and can be regarded as the first solid waste-free zinc refinery.