Wasting the Nation.indd - Groundwork
Wasting the Nation.indd - Groundwork
Wasting the Nation.indd - Groundwork
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Chapter 4: The toxic cradle of productionIscor installed its first coke ovens and by-product plant at Vanderbijlpark in <strong>the</strong> 1950s.They have operated ever since but <strong>the</strong> difficulty of handling <strong>the</strong> waste has largelybeen neglected. In 2004, an environmental impact assessment for Mittal reported<strong>the</strong> annual waste from <strong>the</strong> plant’s coke ovens as 70,000 tonnes of crude tar, 2,400tonnes of tar sludge, 4,000 tonnes of ammonium sulphate and 180,000 tonnes of coke‘breeze’ (fine dust). 72Traditionally, blast furnaces – which are huge steel stacks lined with refractory brick– are used to smelt ore into liquid iron. A mixture of iron ore, coke and limestone isdropped from <strong>the</strong> top of <strong>the</strong> stack and descends through blasts of hot air to <strong>the</strong> bottomover a period of 6 to 8 hours. Very high temperatures result. At <strong>the</strong> end of <strong>the</strong> process,<strong>the</strong> liquid iron is tapped off through one hole while <strong>the</strong> slag floats to <strong>the</strong> top and istapped through ano<strong>the</strong>r. While gas is caught and cleaned by special pipes, some of it isvented to <strong>the</strong> air or burnt as waste. Emissions include dioxins, sulphur dioxide, carbondioxide, carbon monoxide and breathable iron dust particulates.The Vanderbijlpark plant reportedly produced 28,700 tonnes of iron dust (orparticulates), 13,000 tonnes of gas cleaning sludge, 600,000 tonnes of granulated slagand 36,000 tonnes of blast furnace slag from its two blast furnaces in 2004.The iron dust and gas cleaning sludge are recycled to <strong>the</strong> sinter plant and <strong>the</strong> slag isused in <strong>the</strong> cement industry and for road construction. A sinter plant prepares sinters– pellets of iron and coal dust – to feed into steel making furnaces.Molten iron from <strong>the</strong> blast furnace, sinters and scrap metal are used as feed for <strong>the</strong>steel making furnaces of which <strong>the</strong>re are two kinds: basic oxygen furnaces (BOFs) andelectric arc furnaces (EAFs). Mittal uses both at Vanderbijlpark.In <strong>the</strong> BOFs, a lance is used to inject oxygen into <strong>the</strong> furnace at supersonic – and earpiercing– speeds. This drives impurities off <strong>the</strong> molten steel and raises <strong>the</strong> temperatureto melt <strong>the</strong> scrap metal added to <strong>the</strong> feed. Six storey buildings are needed so that<strong>the</strong> huge oxygen lances can be manoeuvred. Fluxing materials are added to carry off72 These figures, and those below, are given in <strong>the</strong> Draft Scoping Report for an environmental impact assessmenton <strong>the</strong> closure of <strong>the</strong> slag heap and <strong>the</strong> opening of a new one (right next to it) at <strong>the</strong> Vanderbijlpark site, preparedby consultants Strategic Environmental Focus.- 100 - groundWork - <strong>Wasting</strong> <strong>the</strong> <strong>Nation</strong>