Cement Energy and Environment

For the last 20 years, French cement plants have been putting their kilns at the disposal of companies and municipal ities to incinerate industrial and other wastes, saving on production costs and c leaning up the environment in the process. f-rench companies are using special industrial wastes to fue l kilns to the necessary2,642° F. This results in the destruction of the wastes at great effi ciency without generating toxic residues or emitti ng fly ash. Orga ni c compounds are trans formed into s impl e molecu les. like water or carbon dioxide, while heavy metals and halogen salts are neutralized in the clinker that produces the cement. All ana lyses up to this point have shown that the cement quality is not affected by using alternative fuels. Besides the obvious environmental reasons for doing so, French producers are finding there are economic reasons for incinerating waste. ''Cement producers prefer to burn waste that is nearly free as opposed to expensive, market price fossiI fuels," said Daniel Lcmarchand, international development manage r at Teris, the rep lacenl ent-fuel arm of the French water treatment company Suez Lyonnaise des Eaux. According to government estimates, tn 1998 waste burning saved 300,000 oil-equivalent metric tons. What is more, the cement industry has helped eliminate around 600 ,000 tonnes ofwaste. One-third of all the country's special industrial wastes is now eliminated in j oint treatment centers. With this success in hand, French companies are increasingly offering their expertise and experience abroad. Residue.\·.fi·om cars, coW.\' IndustriaIwastes lend to have a high calori fie value and can replace foss il fuel s. For example, a high proportion of used oi ls, greases and so lvents fini sh their lives in cement plants. Used tyres are another form of composite waste much appreciated by cement producers. They contain polymers with high calorific val ue that can replace fossil fu e ls, and a stee l carcass th at ca n sa t is fy the requirements for iron in th e clinker. Some plants are combining them beforehand. while others usc special equipment to load them into the kiln as they are. In Alsace, in eastern France, Ciments d'Origny has started an ambi tious program of used tyre recovery. The company equipped its cement works at Altki rch with an automatic system for handl ing shredded tyres. It is now in the process ofestabl ishing a regular supplier. French automaker Peugeot SA, together with a recycling firm , Compagnie Francaise des Ferrailles, have built a plant near Lyons in central France for the disassembly and recovery of scrap vehic les. The materials and remnants that cannot be recovered are ground up and burnt in a neighbouring kiln. Near Bordeaux, in southwestern France, a cement plant owned by Ciments Calcia burns various special wastes, incl uding an imal meal from slaughterhouses. Th is has been particularly useful since the onslaught of the "Mad Cow Disease'' crisis that has swept across Europe. Teri s and Recuperation Traitement Regeneration (RTR), both subsidiaries ofSuez Lyonnaise des Eaux, specialize in the prod ucti on of repla cement fue l for cement faci lities. RTR has opened its fourth pl ant for the treatment of waste oil near two cement plants in the Bordeaux region.The installation, which cost about 53.3 miII ion, treats 20,000 tpy ofwaste, receiving tankers of industrial hydrocarbon waste, such as lubricants, oi Is, adhesives and so lvents. The most liquid waste is pumped untreated as fue l into the kilns. The most viscous. such as adhesives or heavy hydrocarbons, are mixed with sawdust from furniture factories. This impregnated sawdust is loaded into the kilns in the same way as coal. French cement producers &re not restricting themselves to the elimination of industria l waste, however. Many are considering burn ing dehydrated sludge from urban water treatment plants. Some are even t~ i nk ing about burning the remains of household waste after the removal of recoverable materials, such as glass and metal s. Thi s sorted waste cou ld then be finely ground and used in the production of cement, rather than being dumped inro landfi lls or burned in ordinary industrial incinerators. • 15