CEMENT PRODUCTION

From Big Medical Encyclopedia

CEMENT PRODUCTION,

occupational health. C. the item — one of the leading industries of construction materials. Cement represents thinly ground powder of mineral cementitious matters used generally for production of the concrete applied in the form of monolithic and combined concrete and steel concrete designs.

Raw materials for C. items serve silicates and calcium aluminates — limestone and clay, lime marl, etc. By production of waterproof puzzolan portland cement and acidproof cement also quartz sand or other kremnezemsoderzhashchy materials, napr, bergmeal, a molding, etc. is used.

To the main profvrednost of C. items belong dust (see), an adverse microclimate (see) and noise (see).

During the crushing and a grinding of raw materials and a cement clinker (the komkovaty weight baking in furnaces at t ° 1500 °) and especially during the packaging and unpacked shipment of cement the content of dust in air of a working zone quite often exceeds maximum allowable concentrations. Emissions of C. items can contaminate free air in the territory of the plant and extend out of borders of the sanitary protection zone of the enterprise since depending on extent of purification of the pylegazovy mix departing from the rotating furnaces and cement mills various amounts of dust can come to the atmosphere (up to

4 — 7% of all mass of the produced cement). Dust consists generally of particles of respirabelny fraction (diameter less than 5 microns), on chemical constitution belongs to silicates and contains hl. obr. the connected silicon dioxide (see Silicon), oxides of aluminum, calcium and iron, and also biologically significant microamounts of chrome, manganese, lead, concentration to-rykh in dust 10 — 20 times higher, than in raw materials. Majority of working main professions of C. the item is affected by the dust which is contained in air during all working day.

The microclimate in pits and not heated rooms of raw and transport and packaging workshops depends on climatic conditions of the district where the enterprise, and a season of year is located. In the heated rooms of raw workshops constant receipt of big mass of cold raw materials causes cooling in this connection thermal feelings at working do not correspond to the air temperature of a working zone. In oven workshops specific thermal loading exceeds 20 kcal! m in an hour. During the summer period of year air temperature in workplaces of operators of the rotating furnaces can reach 37 — 49 °, at instrument assemblies 25 — 38 °, at sedimentary cameras 25 — 42 °, exceeding outside on 7 — 21 °. Intensity of thermal radiation in workplaces in oven workshops 0,5 — 5 kal/cm2 - min. Especially unfavorable conditions arise during repairs of furnaces. Works on recovery of a futirov-ka are performed at air temperature in the furnace 45 — 70 °, and sometimes above.

During the crushing and a grinding of raw materials and clinker workers are influenced by the noise which is characterized by dominance of averages and high frequencies, intensity 90 — 120 dB.

At working C. items under the influence of the increased concentration of dust can develop hypertrophic and atrophic damages of a mucous membrane of a nose, throat and throat, in emergence to-rykh an essential role play hygroscopic and astringencies of cement. At a long standing of work (10 — 15 years) at working mill and transportnoupakovochny workshops the chronic mechanic bronchitis is sometimes observed (see), the pneumoconiosis (see) intersticial is more rare than type, characterized by rather high-quality current and slow progressing, seldom complicated by tuberculosis. At the workers occupied in production of puzzolan portland cement and acidproof cement the silicosis (see) a typical nodular form with a tendency to progressing and complications is noted. At certain workers as a result of allergenic action of the compounds of chrome (see) which are contained in cement dust menut to develop astmoidny bronchitis (see) and bronchial asthma (see), and also professional dermatitis (see) and eczema (ShM.). Cement dust at hit on a mucous membrane of eyes can cause the acute conjunctivitis (see) sometimes passing into a chronic form. Cases of a burn of a cornea (see an Eye) after hit in eyes of a large amount of powder of cement are noted. At working producing departments of C. the item is registered the increased incidence of diseases of a respiratory organs, skin, digestive organs and a peripheral nervous system leading to temporary disability.

For pollution control of air dust carries out sealing tekhnol. the equipment, replacement of mechanical transportation of the dry and raising dust materials by pneumotransport, cleaning of dust from a floor, walls and the equipment by means of vacuum devices. Effective dusting of kiln gases and the aspirated air by means of special devices — cyclones and electric precipitators is necessary, at a cut the caught dust system of pneumotransport moves back in the furnace (see. Sanitary protection of free air). During the performance of short-term works in the conditions of the high content of dust in air it is necessary to apply respirators like «Petal» to individual protection of a respiratory organs (see Respirators).

For elimination of a heat gain aeration of buildings is carried out, cases of the rotating furnaces are located in the open air. Cabins of cranes shall be equipped with conditioners with purification of the given air of dust (see Air conditioning). Complex automation tekhnol. process with a remote upravleniyekhm the equipment provides radical improvement of working conditions of operators of the rotating furnaces and drivers of grinding mills.

For the purpose of early diagnosis of a mechanic bronchitis and a pneumoconiosis carry out periodic medical examinations (see. Medical examination). The diagnosis of professional dermatitis and eczemas is confirmed by positive epikutanny test on chrome (see. Foot tests).

Bibliography: Artamonova V. G. and

Shatalov H. H. Occupational diseases, page 38, M., 1982; The Guide to occupational health, under the editorship of F. G. Krotkov, t. 3, page 467, M., 1961; Sadkovskayan. And. and M and c and to V. G. Industrial hygiene of construction materials, M., 1962; Shchebunyaev G. F. and Bokhan ý-to about G. I. Labor protection at cement works, M., 1981. B. T. Velichkovsky.

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