Disposal of Dust Made in Quartz Manufacturing Three

COMPLIANCE WITH PROVISIONS

In some of the manufacturing enterprises, there were provisions for dampening and wetting the stones before they were fed to the crusher. However, it was stated by the management that the dampen- ing and wetting of stones at the initial stage does not help in producing a quality product as the mass becomes sticky, which renders it unsuitable for sub- sequent processing. As such, manipulation of stones at present does not comply with the provisions relat- ing to the control of dust at the source (Ministry of Labour, 1987). In consideration of these specific and serious problems of dust emission and its further dispersion in the work atmosphere, recommen- dations for the control of dust have been given to the management of the quartz manufacturing indus- try.

SITE SELECTION

Since most enterprises manufacture similar pro- ducts from the same basic raw material with mostly identical processes, it was decided to restrict the study to six enterprises. A, B and C were stone crushing enterprises located in Jaipur, in the indus- trial area, residential area and mining area, respect- ively. Quartz manufacturing enterprises D, E and F were located in the industrial area of Ajmer. D and F manufacture quartz powder from quartz stones by ball milling. Enterprise E manufactures quartz powder by using a special stone (ore) as the raw material.

MATERIALS AND METHODS

Samples of airborne dust were collected in the breathing zones of the workers during stone crush- ing and quartz manufacturing operations. The air- borne `total’ dust samples were collected on a glass fibre filter paper or membrane filter paper of 37 mm diameter, having 0.8 mm pore size, fitted in a Millipore holder, using a personal sampling pump (Casella, London) at the rate of 2±3 l/min for 30± 120 min. The airborne respirable dust samples were also collected on a membrane filter paper of 25 mm diameter, of 0.8 mm pore size, by using a cyclone separator (Higgins and Dewell, 1967) at the rate of 2 l/min for 60-180 min. The collected airborne dust samplesDboth `total’ dust and respirable dustD were weighed.

The free silica contents were deter- mined by the Talvite method (Talvite, 1964). The Factories Act, 1948, amended in 1987, pre- scribed Permissible Limits of Exposure (PLE) (Government of India, 1987). For dust containing quartz, the PLE is based on the concept that the toxicity of the dust is proportional to the concen- tration of quartz in it. In order to have a method of maximal simplicity for routine monitoring of dust concentration, total and respirable dust PLEs have been adopted as follows:

PLE for total dust containing free silica = 30/(% quartz+3)

PLE for respirable dust containing free silica= 10/(% respirable quartz+2).

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