Cement, Energy and Environment July-Sep 2002

blasting using explosives. Through the introduction of hydraulic rock breaker, whose hydraulic hammer breaks all the boulders, secondary blasting has been dispensed with. Limestone transport to crusher During the transportation of limestone from the mines to the primary crusher by 35-ton dumpers, a lot of dust gets air-borne from the haulage roads by the constant to– and-fro movements of the dumper trucks. This generation of dust from the ro ads is mimini sed though FigureJCompostingpitwithleavesdumpeJ sprinkling of water on the haulage roads. A water sprinkler of 28000 litres capacity is utilised for the purpose. Limestone crushing an£1 stacking The process of crushing generates a lot of dust as do the subsequent operations like its conveyance, transfer, stockpi ling and reclaiming. To suppres_s dust emissions at all these st"ge s, atomised water is sprayed by means of high-pressure nozzles at the crusher hopper, the apron feeder, the impact crusher inlet , the impact crusher proper and two places over Figure 4 Aerator at work in the sewage water treatment plant the conveyor belts which carry the crushed limestone to the stockpile. The atomised water spray system installed has considerably reduced fugitive dust emission at the crusher hopper as well as all belt transfer points; for instance, it is less than 300mg/~L 1 at the transfer point before limestone stacking (mines). Likewise, moistening has its beneficial effect while stacking the crushed limestone at the stockpile. The stockpile is of 13m height. The crushed limestone having been moistened does not give rise to dust during its fall. In addition, the fall height is normally maintained at 4- Srn to minimise dust generation and Figure 5 Rain water harvesled.from e.x:ploited 1i1ines being utilisedfor irrigation. 1 . ....