OVERVIEW OF MODERN MEANS OF DUST PROTECTION IN METALLURGY

Report 1. Filter materials

Abstract

One of the most effective ways to protect an employee's body from industrial dust is to pass dust-laden air through a filter material. This method is used both in respirators and in filters for purifying air or industrial gases. The indicators characterizing the operation of filters are the coefficient of permeability, efficiency, time of protective action, resistance to inhalation and exhalation (for respirators), and others. The article describes modern materials for filtering gases, including air, their properties, advantages and disadvantages, and application features. For previously widely used materials based on perchlorovinyl, the cleaning efficiency decreases at air temperatures above 301 K and at high humidity. Instead of them, filtering materials based on ultra-thin fibers of a copolymer of styrene and acrylonitrile, as well as obtained from a polypropylene melt with an electrostatic charge, are proposed. For fine cleaning of gases, at elevated temperatures, filters are used from ceramics, fine-fiber wool from stainless steel, which have high strength and resistance to variable loads. Materials obtained from the melt of Forton PPS grade polyphenylene sulfide rubbers are effective. In Italy, for the first time in the world, casein fiber lanital was used. The modern newest types of filters include HEPA (High Efficiency Particulate Air or High Efficiency Particulate Arrestance) filters with an efficiency of up to 99.995%. The filter is made of fibrous material (fiber diameter 0.65…6.5 microns, the distance between them is 10…40 microns).The operation of these filters is due to the processes of diffusion, inertia and engagement. Diffusion is caused by the phenomena of adhesion and autogenesis. Adhesion is the interaction of dust with the deposition surface, in our case with HEPA fibers. Due to the adhesion on clean fibers, the first layer of dust appears. Autogenesis, or sticking together, is the interaction of dust particles with each other. Due to the autogenic interaction, the particles continue to layer on top of each other, forming multilayer conglomerates on the fibers.The article discusses these processes, their influence on the efficiency of capturing particles of different sizes.