Situational tasks for control on material mastering.

Task No.1. At dry pneumatic drilling in mine concentration of a dust in a breath zone fluctuated from 234 to 800 mg/m3; 95 % of all dust make particles in the size 0,5 – 5,0 microns. At carrying out of periodic medical inspections in two mines

The following is revealed: on mine № 1 (the maintenance of a free dioxide of silicon about 38 %) – 6 cases silicosis, at 65 % of mucous top respiratory ways working irritation, at 25 % - mucous an eye and at 7 % - irritation of a skin;

On mine № 2 (the maintenance of a free dioxide of silicon nearby 1 %) – 1 case anthracosis, at 49 % working – irritation of mucous top respiratory ways, at 2 % - irritation mucous an eye, at 2 % - skin.

1. Compare the specified sizes of concentration of a dust to maximum concentration limit and specify a role of dispersion of a dust in occurrence of a pathology of respiratory organs.

2. Estimate, what of the specified kinds of pneumoconiosis is more dangerous for working.

3. Make the plan improving action at chisel works.

Task No.2. On buck – concentrating factory at medical inspection of workers (age working 25 – 40 years, the work experience at the given enterprise over 6 years), at 85 % have been revealed the expressed changes of a mucous membrane of the top respiratory ways (rhinitises, pharyngitises, dryness of a mucous membrane, infringement of sense of smell). All workers are exposed to the dust influence, formed at processing of the dolomite which concentration makes: in summer months – 14 – 25 mg/m3, in winter at partial switching-off of communications of water supply – 49 – 610 mg/m3

1. Compare the specified concentration of a dust to maximum concentration limit for dolomite and lime.

2. Estimate from hygienic positions of a working condition of the working.

3. Offer the plan action for improvement of working conditions.

Task No.3. In transport - raw department of factory of ferro-concrete products working are exposed to influence of a dust of cement and sand at their unloading, transportation on a warehouse and in to mix concrete department. Concentration of a dust of cement thus fluctuates within 180 – 560 mg/m3, sand – 8-36 mg/m3 with the maintenance in it of a free dioxide of silicon to 85 %.

At medical inspection of 510 workers with the experience of 80-25 years at 20 surveyed it is revealed of pneumoconiosis 1 stages, from them 16 persons were workers transport - raw department.

1. Compare the specified sizes of concentration of a dust in a zone of breath of workers to maximum concentration limit.

2. Define, with action of what of adverse factors is etymologically connected development pneumoconiosis.

3. Offer the plan improving action.

Task No.4. At factory on ammonium reception at extraction of alumina from bauxite ores in the course of preparatory processing of raw materials the dust is formed at all processes of warehousing, crushing and moving of bauxites. At processing of ores with average moisture content of 18 %. Average concentration of a dust makes 115 mg/m3, at decrease in humidity to 10 % - about 180 mg/m3. In branch calcination at pour the calcinated alumina, transportation and an unloading concentration of its dust reaches 225 mg/m3. Influence of aerosols is shown in a pathology of the top respiratory ways (catarrh, rhinitises, pharyngitises, a laryngitis) at the expense of alkaline reaction of aerosols, at long contact to an alumina dust - in – a kind of a specific pneumoconiosis – aluminosis.

1. Compare the specified sizes of concentration of a dust in a zone of breath of workers to maximum concentration limit.

2. Specify, how humidity of initial materials influences intensity formation of a dust and level of a dust content of air in working premises.

3. Make the plan of improving actions.

Task No.5. One of woodworking stages at furniture factory is preparation of surfaces of details of the future furniture by their grinding on machine tools before definitive furnish (varnishing, polishing). These processes are accompanied with dust allocation. At studying of a dust content of air the following data has been obtained. The weight of the filter before selection of test of air was equal 35 mg., and after test selection – 40 mg. Tests were selected within 20 minutes with a speed of 15 l/minutes At studying of qualitative structure of a dust it has appeared that it (a wood dust) contains 1,5 % free dioxide of silicon.

1. Define concentration of a dust and compare it to maximum concentration limit.

2. What devices are necessary for definition of a dust content of air by a weight method.