Cement Energy and Environment

>- LOW-CARBON FLYASH FORUSE IN CEMENT AND CONCRETE PRODUCTION IN USA* F. lyaslt, a lwzardous ami ecologically degrading waste, It as been creating a lot of stir among ecologists in recent years! In India, with galloping power generation through thermal power plants, tlte annual jlyaslt generation will surpass muwal food grains production wit/tin the next decade! Alternative uses ofjlyasll are many and are effectively implemented in most developed countries. In India, witere only 2 to 3 per cent of tlte jlyasll generated mmually is reused, litis article from PMET will throw some new fig !It upon avenues of quality enhancement offlyash for its recycling -Ed. PittsburgMineral & Environmental Technology (PMET) and Hosokawa Micron Powder Systems announced that they have entered into an agreement to commerc ialize PMET's newly developed process for producing low- carbon ny ash util izing Hosowaka's particle sizing/ classificationequipment. The agreement ca ll s for PMET and Hosokawa to cooperati ve ly market a comp lete technology and equipment package geared toward operators of coal- fi red power plants, ash marketers, and concrete and cement producers. The PMET process uses ai r-jet milling and simultaneous air classification equipment to reduce the carbon content of the ash and improve ash pozzolan icity. The as– combusted ash is introduced into the jet mi ll where the carbon is preferentially ground by particle-to-particle impact in the lower portion ofthe mill. Concurrently, the ash is continuous ly subjected to a controlled-velocity, upwardly moving air stream that carries the lower- density, high-carbon ground fraction upwards through a rotating classifier wheel from which it is discharged from the upper portion ofthe unit. The desired carbon content of the low-carbon ash is achieved by contro lling air velocity, classifier rotational speed, and grinding time. • FLYASH INCEMENT AND CONCRETE IN USA* M ore than60 million tons offly ash are generated every year by coal burning plants and other industrial installations in USA. Of this total, about 40 million tons are landfi lled at sign ificant costto industry and consumers. Ofthe remaining 20 million tons, about I0 million to ns are r eused in cement and concrete * Courte.sy : Cement Americas, Oct. 1999 products, appl ications that yield the highest value for ash, provided that the levels of unburnt carbon and ammonia·in the ash are low. • 19