At machinetool and metalworking plants, the largescale generation of dust and noxious gases is mainly associated with casting, forging, pressing, modeling, and mechanical operations. Industrial dust consists primarily of iron and manganese oxides, as well as some compounds of magnesium, aluminum, and other elements. A considerable quantity of dust enters the air as a result of the preparation of molding mixtures, the emptying of molds, and the operation of tumbling drums and other equipment. Volatile dust formed in machinetool and metal� working plants generally contains a whole range of ele� ments. Heavy metals released as fine aerosols pose a particular risk to humans, animals, and plants. Heavy metals are protoplasmic nuclei, whose toxicity increases with increase in atomic mass. The toxicity of heavy metals is differently expressed. At high concen� trations, many heavy metals (copper, mercury) inhibit enzymes. Some heavy metals (iron) form chelatelike complexes with ordinary metabolites, thereby disrupt� ing ordinary mass transfer. Metals such as cadmium and copper interact with cell membranes and change their permeability and other properties (for example, rupture of cell membranes). Some heavy metals com� pete with elements that are necessary to plants, thereby disrupting correct functioning. For example, cadmium displaces zinc, and the resulting zinc defi� ciency may result in plant death. The toxicity of mer� cury depends on the particular compound. The most toxic are organic compounds: methylmercury, dime� thylmercury, and ethylmercury. A high lead content may suppress plant growth and provoke chlorosis due to disruption of iron supplies. At machinetool and metalworking plant, two main systems of dust capture generally operate: a technologi� cal system and a healthrelated system. The technolog� ical system extracts dust and toxic gases from the dust- gas-air emissions used for technological purposes; the healthrelated system is intended to protect the atmo� sphere from toxic pollutants in the dust-gas-air emis� sions formed in the production process. The treatment of industrial dust-gas-air emissions is necessary to improve working conditions and also to permit the extraction of valuable components from the dust. At many manufacturing enterprises, the processing of various materials releases specific dust into the workplace atmosphere. In particular, the use of PVC (film, fiber, electrical insulation, pipe, linoleum) is associated with the release of considerable dust (PVC and its disintegration products) into the air. This may result in acute and chronic poisoning of the workers. Direct contact with PVC dust may lead to pathological changes in the respiratory system. Gas welding and electrowelding releases large quantities of fine dust— consisting of iron oxides with added manganese, sili� con dioxide, fluorides, and other compounds—into the air of assembly and other shops. Welders and gas cutters are at risk of pneumoconiosis. Knowing the chemical composition of industrial dust-gas-air emissions at machinetool and metal� working plants, we may identify the sources of pollu� tion; establish the range of pollutants; and more pre� cisely assess the pollution burden on the atmosphere and the possible environmental risk to public health. We need to know the chemical composition of indus� trial emissions in order to organize environmental monitoring at machinetool and metalworking plants, to improve systems for the suppression and treatment of industrial emissions, and to select appropriate uses for the collected pollutants.
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Jul 1, 2023
M Fayaz + 3
Open Access