An Investigation into the dust problem in mica mines

India produces about 80 per cent of the world production of mica. About 9,000 peple are engaged in nearly 287 mica mines in this country. Mica usually occurs as veins or lenticular intrusions into the surrounding pegmatites. In the working out of mica either by opencast or underground mining, recourse is taken to drilling in the associated rock and then blasting it. In the work of drilling and blasting and handling of the product, thus obtained, there are scopes for production and dispersion of a large quantity of dust in the surrounding air. This dust usually contains high percentage of free silica. Work under such dusty condition for long period is likely to cause silicosis to the miners, exposed to it. With a view to finding out the potentialities of silicosis problem in our mica mines, an investigation was made in 15 such mines of koderma and Tisri regions in Bihar. The study includes the determination of dust concentration in air in the reparable size range of the free silica content of the dust. The result shows that the averagte dust concentrations produced in air during drilling and blasting operation are usually above the threshold limit values for safe work with such dust. The condition created during the loading/mucking operation is, however, within the safe limit prescribed. It thus shows that wet drilling and water spraying which are practiced n mica mines even now are to be made more effective and efficient to make the working environment safe for miner’s health