Obtaining lead and chromium crown
Getting the lead and chromium crown belongs to a very hazardous industry. Enterprise for the production of foliage is usually thin with periodic processes and significant manual labor. This will exacerbate the harm of production, as well as good ventilation of such enterprises is difficult. With the ventilation point of view of the production crown characterized as an enterprise "small" chemistry.
The starting materials for the production of foliage are litharge (lead oxide PbO), potassium bichromate (bichromate) and hydrochloric acid. Own raw materials entirely poisonous, not less toxic and finished products - the crown.
Potassium bichromate comes to the enterprise in crystals or melting. In both cases, it is subjected to the dissolution of n hot water vapor. Dissolution of potassium bichromate, especially crystalline, is in hiding closet type, in which the entire apparatus is dissolved. From the shelter is an intensive air suction, which creates the velocity in the working aperture of at least 1,3 m / sec. In the design of local exhaust should be carefully taken into account gaps and leaks.
Litharge is delivered to the company in plywood drums. This is a heavy powder, relatively little dusty. Harmful operation is rastarivanie litharge, and upload it to the reactors, since these processes, although not extensively, but stands strong toxic dust. Opening of the drums is made in cabinet shelters with local suction. A design speed of the openings and crevices shelter should be about 2 - 3 m / sec, depending on the conditions of dust formation.
Reactors for dissolving litharge and for the synthesis of crown provided with local suction with mechanical drive. Air velocity in the openings of the reactor is taken not less than 1,5 m / s because of the possibility of dust formation.
Substantial naughty production crown is toxic dust, including dust dried product. Unloading of dryers and transportation of the dry product augers and elevators, as well as packing crown in paper bags - these processes are the main suppliers of the toxic dust. Gidroobespylivanie here is unacceptable, the only measure of dust control equipment is sealed with an appropriate aspiration. In the design of aspiration are very important two things: enough removed by aspiration of air and reducing pyleunosa by developing cross aspirating funnel.
In determining the amount of air removed by aspiration, which increases the coefficient 6, which takes into account the toxicity of the dust should be within the 1,5-1,8 and even to 2. We recommend using secondary-intensive shelters at all locations shipments dusting of the product: from the elevator to the auger from the auger in the auger, etc.