Production of mineral pigments
Enterprises producing mineral pigments, are typical for chemical production of small scale. The largest of these establishments - plants producing titanium dioxide - is still in its scope can not be compared with the production of "great chemistry".
Availability of emergency ventilation
Despite the relatively modest size, manufacturers of pigments sometimes are more complex ventilation, rather than the production of basic chemicals such as sulfuric acid and superphosphate.
We consider the ventilation of factories producing titanium pigments, lithopone and crown.
Production of titanium pigments, which are almost pure titanium dioxide in the Soviet Union emerged recently. In this production there is no sufficient experience in both technology and health technology. Technology for producing pure titanium dioxide is complex and poorly understood. In the Soviet Union used method, developed in Italy.
From health point of view of production of titanium pigments, the most harmless among all the pigment industry.
Neither the original product, ilmenite or titanium dioxide itself is not toxic; allowable concentration of titanium dioxide in the air of premises 10 mg/m3. In the production of sulfuric acid is used which, although toxic, but has a low volatility. In addition, the rapidly flowing process of decomposition of ilmenite with sulfuric acid is carried out in special reactors, completely isolated from the room and communicating with the atmosphere. Emitted during the expansion of gases and vapors to freely go into the atmosphere and dissipate it at a height of about 30 m above ground level.
Pair, emitted during the decomposition of ilmenite, do not affect the status of air space. They have to be just outside the building and did not have near the reactors, air intake devices.
Obtained in reactors melt is leached with water and recovering the iron shavings to convert ferric to ferrous. The resulting suspension is filtered on vacuum filters - so-called "black filtration. The temperature of the suspension of about 60 В° C, the suspension contains a significant amount of sulfuric acid. From the resulting filtrate released iron by vacuum crystallization. Iron sulphate crystals are separated from the mother liquor in centrifuges, the solution thickens and the residue is hydrolyzed, at which the sediment becomes metatita-new acid. The precipitate was filtered, repeatedly washed by vacuum filters and repulpatsiey, again filtered, dried and calcined in rotary kilns. The calcined product - pure titanium dioxide - are wet grinding, filtering and drying. The dried product is ground to the steam-jet mills, and then goes to packaging. Packing titanium pigment in paper bags manufacturing machines with automatic weighting.
As can be seen from the description of the manufacturing process, toxic substances are formed. The most poisonous sulfuric acid, but their selection is insignificant and is not accompanied by fever. Some of the phones are produced in small amounts of ammonia and hydrogen chloride. Together with hydrogen allocated hollow drop in the reduction reaction, as well as sparging solutions with compressed air.
In addition to minor gaseous pollutant, in the manufacture of titanium pigments released ilmenite dust and dust of the pigment. There vlagovydeleniya of vacuum filters and a fairly significant heat from the reactors of the expansion, rotary kilns, dryers and other equipment working with heating.