ABRASIVE MATERIALS

From Big Medical Encyclopedia

ABRASIVE MATERIALS, occupational health. And. m — the fine-grained or powdery substances of high hardness intended for machining of surfaces of metals, gemstones, glass, a tree, skin, plastic, metal ceramics and other materials. And. m share on natural and artificial. To natural And. m belong: diamond, corundum, garnet, quartz, flint, feldspar, pumice, etc. Majority natural And. the m often does not satisfy technical (bystry wearability, smaller hardness) and hygienic (formation of large amounts of the dust containing silicates and quartz) to requirements.

Are most widespread in the industry artificial And. m: electrocorundum — normal (alundum), white (korraks), alloyed (chromic and titanous) and monocorundum, silicon carbides — black and green (karbokorund), boron carbide, synthetic diamond and cubic boron nitride (an elbor, or borazon). From artificial And. m receive stronger grain in a form approaching isometric; they have bigger abrasive ability (amount of the material removed during the grinding to a zatupleniye of grain) and an opportunity to carry out high-precision processing of products.

And. m are applied in the form of grains and powders, but hl. obr. in the form of the abrasive tool (grinding wheels, disks, segments, smuts of drill bits, the ruling tool, skins, pastes, etc.) which are widely used in the metal-working, ore mining, glass, ceramic, jewelry, paper, woodworking industry, in medicine — it is preferential in practice of prosthetic dentistry and in surgery. And. m have also semiconductor properties, thermal stability and are used in the electro-and radio engineering industry and other industries of the national economy.

For receiving And. the m is used various raw materials: bauxites, pure alumina, quartz sand, petrocoke, graphite, hexagonal boron nitride, various catalysts etc. Osnnovny technological processes of receiving And. m are preparation of a feed stock and furnace charge (mix of initial components in certain ratios), melting or synthesis, destruction of blocks, multistage crushing, degeneration, sowing, enrichment, classification and packaging.

By production of abrasive materials the main profvrednostyo is dust. Operations otkrygo intake of raw materials from transport devices, the place of unloading and loading, etc. maximum allowable concentration of aerosols of electro corundum normal, silicon carbides and boron of 6 mg/m3, diamonds of natural and artificial 8 mg/m3 happen sources of release of dust. Besides, electroheat treatment of furnace charge at a temperature apprx. 2000 — 2500 hail in arc furnaces, in furnaces of resistance, on special pressa with a pressure up to 100 000 atm, and also roasting and calcinating And. m are followed also by other adverse factors (infrared radiation to 7,0 kal/cm2 • mines, temperature increase of air, gases: carbon monoxide, boric, sulphurous and chromic anhydride, phenol, formaldehyde). At enrichment And. m can be allocated vapors of sulfuric and hydrochloric acids, alcohol, chromic anhydride, nitric oxides, etc. Noise of different intensity and spectral structure takes also place. The most high levels of noise — during the work of crushers, spherical mills, mechanical sit also other equipment.

At non-compliance with rules of labor protection there can be occupational diseases. Workers with a long standing have works with And. m in the conditions of high dust content are revealed cases of a mechanic bronchitis (see) and a pneumoconiosis (see). At influence of dust of silicon carbide, besides, fibrous small knots in bifurcation limf are revealed. nodes, the reminding silikotichesky. However proliferation of reticuloendothelial elements is expressed as nodular educations much more weakly, and quantity they are 5 — 7 times less, than at a silicosis.

Measures of fight against adverse factors in production And. m come down to improvement of technological process and sanitary devices: mechanization of handling works, sowing, cleaning sit, casing and packaging; to wetting of the cooled-down built-up blocks and lumpy material before disassembly, sorting and each stage of coarse breaking; transition to hydraulic separation of powdery substances; use of the delivery funnel working at absorption and dry elutriation of grain and powders A. m. An effective action for fight against radiant heat is shielding of sources of heat, intensive water cooling of casings and the shelter of the arch of arc furnaces. Excess of heat is eliminated with correctly organized aeration. Convenient jobs, the regulated breaks in each 1,5 hour of work with obligatory carrying out production gymnastics are necessary for the prevention of a static overstrain, and also tension of sight and attention.

The workers occupied on production And. m and working with them, according to the order of the Minister of Health of the USSR pass preliminary (at revenues to work) and periodic medical examinations of 1 times in 24 months. Contraindications for employment are often becoming aggravated chronic katara of upper respiratory tracts, the expressed atrophic nasopharyngitis, laryngitis, tracheitis, chronic bronchitis, bronchial asthma, emphysema of lungs, a pneumosclerosis, pleurisy, a bronchoectatic disease, diseases of cardiovascular system (heart diseases, a hypertension, stenocardia, etc.), and also the expressed vascular disorders of functional character, chronic diseases of eyes, skin.

Bibliography: Brunstein I. P. and Danilov R. I. Pathomorphologic changes in lungs at influence of dust of boron carbide and monocorundum in an experiment, Medical zhurn. Uzbekistan, No. 12, page 40, 1969; Latushkina V. B. Changes in a respiratory organs at influence of dust of artificial abrasives. Gigabyte. work and the prof. having got sick.,№ 7, page 49, 1960; it, Questions of occupational health in production of artificial abrasives, in kN: Occupational health and industrial ventilation, under the editorship of M. E. Tsutskov and I. A. Zaydshnur, page 53, M., 1960, bibliogr.; it, Studying of fibrogenny effect of dust of natural and synthetic diamond, in book: Fight against a silicosis, under the editorship of A. A. Letavet and P. N. Torsky, t. 8, page 178. M, 1970.

V. B. Latutkina.

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