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Metal Casting Technologies : December 2007
he Indian foundry industry comprises of nearly 5000 units mainly spread across more than 20 clusters. Some of these foundries are outside the clusters and play a minor role in the total production. Most of the units are small-scale family owned foundries having minimum infrastructure. They mostly cater to local markets in the clusters. While foundries in a cluster might be predominantly manufacturing a typical application oriented castings, in another cluster the units would be mostly manufacturing some other category of castings. While the local markets have an influence on the type of castings being produced, they also have an influence on the quality of castings. In foundries, there are various processes that result in the generation of emissions of particulate matters and volatile organic compounds (VOCs) in the shop-floor, which poses health hazard to the workers. These can be classified into the following major types: POLLUTION IN PATTERN MAKING SHOP In wooden pattern shop, suspended wood flour is the main pollutant. It can also cause fire hazard above certain concentration, if ignited. In general, the wood flour is not considered as harmful due to its natural characteristics, provided its concentration is not too high. POLLUTION IN MOLD AND CORE MAKING SHOP This section of a foundry is a source of major pollution. Silica dust is the main pollutant in the form of suspended particulate matters (SPM). When inhaled for several years, the worker exposed to it may develop silicosis. The susceptibility, however, to silicosis depends on various inherent factors of a worker in addition to the level of SPM and the number of years of exposure. In addition to SPM, there are many other pollutants in the mold and core shop in a foundry using chemical binders. The organic solvents, catalyst and hardeners are the primary sources of the pollution in addition to the binder itself. Various VOCs are generated in the sand mixing/mulling area, mold/ core shop and ultimately the effect may extend to the pouring line. POLLUTION IN MELTING SHOP Particulates, including smoke, dust and fume, have always been a major constituent of air pollution in the melting shop. The major source of pollution in melting shop is cupola. The emissions from a cupola consist of SPM, SO2, oxides of nitrogen and carbon monoxide. The level of emission of SPM depends upon a number of factors such as the design of the cupola, composition of raw materials (especially ash content and sulfur content of coke), volume and velocity of the air blast, blast temperature, melting practice etc. About 50% Pollution in Indian Foundries By P. C. Maity Director, CAPARO-PTU School of Manufacturing and Materials Technology Kapurthala, Punjab, India T Environmental Report METAL Casting Technologies December 2007 38 Global warming with the foc us on India.