Cement, Energy and Environment

due its lower cos t and high calorific va lue. However, due to poor ignition and burnout properties, petcoke has to be very finely ground, therefore reducing the production rate of the coal mill. The use of petcoke is also limited by its very high sulphur content. As a result, the only way to use 100 per cent petcoke is bymeans of a bypass system. This article presents the process problems caused by the use of petcoke, along wi th valuable solutions developed by KHD Humboldt Wedag. Courtesy: In ternational Cement Review, Mar. 2002, Pp. 71-73. Email: inlo@CemNet. co. uk Web: www.CemNet.com A NEW PROCESS REVOLUTIONISES TYRE RECYCLING R. Balachandran/ California Irrespective of where they are dumped, scrap tyres pose a serious health and environmental hazard. Abandoned tyres collect rainwa ter, and the rubber builds up heat - the perfect nesting environ,ment for many an insect. Studies show that the incidence of encephalitis, a disease sp read by mosquitoes, is higher in areas near tyre dumpsites. These dumpsites are also major fire hazards. In the US, a p ile of nine million tyres burned out of control in Winchester for almos t a yea r causing severe environmental damage and 14 milli on tyres burned ou t of control in Ontario for weeks ca using seve re groundwater contamination. It is in this context that the innovative recycling and con serva tion technology of Integra ted Techn ology Group Inc, Oklahoma, is a ray of hope. The group 's pa tented gassifi ca tion recycling process ensures that shredded tyres are comp letely recycled. This new process utili ses proprie tary technology that creates gassificati on, distillation and recycling. In thi s energy efficient vapori sati on process the original elements that go into making tyres-primarily oil, s teel nnd carbon-are extracted in recyclable form. The process ha s a low thermal temperature and low opera ting costs. What makes this process unique is that there is n o burning of t yres. The scra p tyres are shredded into two-inch chips and fed into an indirect-fired rotary ki ln that acts as a convection oven. At the operational temperature of around 353°C, the tyre chips turn into gas. The gases pass through a scrubber and enter a condenser. Oil is formed from the current insert and is pumped through filters. The lighter gases, not condensed into oil, a re compressed into gas storage tanks where a portion of the gas is red irected to heat the kiln. The gases can also be used wi th a reciprocal engine to create electric power. The oil can be marketed to oil refineries for further refinement and used to fuel electric generators or as blend oi l in va rious applications. The leftover byproducts of the gassifica ti on system are carbon powder, steel and a sma ll amount of ash, mainly from the fabric cord used in tyres. The carbon powder can be used in foundries in steel prod uction. The carbon steel wires from the tyres can be marketed to steel mi lls. The remaining ash, 2 per cent by weight, is mainly inert and can be used in landfills. Scott Holden, the president and CEO, expects it to be of relevance to develop ing countr ies like India, "We look forward to joint ventures or working with the governments directly," he says . " As we do n ot intend to se ll the technology, we want to be involved in an y project where our technology is being used" Courtesy: The Week, 28 Apr 02, P 54. ,_