Wasting the Nation.indd - Groundwork

Chapter 4: The toxic cradle of productioncommercial construction has contracted sharply and the market is being sustainedby the state’s infrastructure programme, starting with the 2010 stadiums and withmassive demand from Eskom and Transnet’s expansion programmes to follow.The raw materials of cement production are limestone and silica and alumina from clay.They are ground to a fine powder and then fed through the kiln, where temperaturesreach 1,400° to 1,500°C, to produce ‘clinker’. Kilns are traditionally fired by coal andthe bottom ash is incorporated in the clinker. The clinker is then cooled and groundwith various additives to the fine powder that is cement. The process is very energyintensive and the use of coal puts cement in the same bracket as the energy sector interms of its contribution to climate change.Internationally, the Cement Sustainability Initiative is putting a green spin onproduction but, as Jane Harley comments in a report for groundWork, it “has putout a great many documents, all of which avoid the central truth – that cement cannever be sustainably produced”. Rather, the industry has focussed on “the use of …‘alternative fuels’, which translates to the use of waste as a fuel” [2006: 2]. Whilethe environmental benefits of these fuels are dubious, the economic benefits to thecement industry are evident. Since 2003, coal prices have risen from around US$20to over US$160 a tonne. PPC comments that international demand is limiting “theavailability of the appropriate coal quality for cement manufacture” while “spiralling”international prices are pushing up costs [PPC 2007: 24].The industry describes burning waste as ‘co-processing’ or ‘energy recycling’. PPCgoes so far as to suggest that co-processing replaces “fossil fuel with renewable sources”[50]. Apart from twisting the notion of ‘renewable’ beyond recognition, the statementimplies that waste will indeed be eternally renewed. The industry favours waste witha high calorific content, many of which are hazardous petrochemical wastes derivedfrom fossil fuels. Wastes used internationally include solvents, old tyres and oil, paintand dried sewerage sludge. The use of spent pot linings from aluminium smelters hasan added advantage as the alumina substitutes for alumina in the raw material fed intothe kiln.Pot linings and dried sewage sludge are already used in some plants in South Africawith the approval of the DEAT. It is possible that other wastes have been used withoutapproval. Used tyres, however, would require modification of the kilns and the industryis, somewhat impatiently, “waiting for the relevant legislation to be enacted”, as PPCWasting the Nation - groundWork - 123 -