Aggressive waters

Aggressive waters

AGGRESSIVE WATERS (EN: aggressive waters; DE: aggresives Wasser, angreifendes Wasser; FR: eaux agressives; ES: aguas agresivas; RU: агрессивные воды) are the waters, which are actively entering into the chemical reactions, which break various structures of concrete and metal (for example, the roof supports of the mine workings) and equipment, adversely influencing the flora and fauna of the water bodies as the result of the impact by the salts and gases, which are contained in the water.

The aggressive waters may be natural and artificially emerged during the process of the mining works, during the discharge of the wastes of the chemical, metallurgical productive enterprises, etc. They distinguish the following types of the aggressivity of the waters: the carbon dioxide one, with the content of the aggressive carbon dioxide of more than 4.3 milligrams per litre, the leaching one with the content of the HCO3- ions of more than 0.4-1.5 equivalent (sic, Russian system) milligrams per litre, the general acidic one (pH < 6), the sulfate one (SO2-4 ions of more than 250 milligrams per litre), the magnesian one (Mg2+ ions of more than 750 milligrams per litre), the oxygenated one. They decrease the influence of the aggressive waters by the control of the regimes of the inflow of the surface and underground waters and the drainage of the mine waters, by the decreasing of the time of the contact of the waters with minerals, by the decreasing of the temperature and the rate of the renewal of the solution. In order to do this, they use: the lowering of the level of the water from the surface through the drilled wells, which are equipped with the submersible pumps; the underground drainage by the preparatory workings and advancing drilled wells; the decrease of the inflow of the water into the goaf space and of the losses of the minerals with the high content of sulfur; the rational system of the collection and purification of the acidic mine waters. Before the drainage and the discharge into the surface water streams and water bodies, they clean the acidic mine waters of the suspended substances in the settling tanks, neutralize by the lime, lime milk, caustic soda.

At the beneficiation plants, the closed loop water supply system is used along with the settling tanks and the neutralization of the waters. The tailings storage facilities of the products of the benefication with the content of the sulfide minerals are fenced around by the water tight plates. They decrease the destructive action of the aggressive waters on the metal by the usage of the acid-resistant and corrosion-resistant equipment and machinery, which are made with the usage of the alloying elements in the alloys, by the usage of the films with the high energy of the loosening (which slows the corrosion and increases the durability of the metal), by the introduction of the nitrogen into the chromium steel. For the mine drainage with the high pressures of the aggressive waters, they are using the lined and fiberglass pipes, and with the low pressures they are using the pig iron, eternit, asbestos-cement ones. In the oil and gas industry, during the burial of the industrial waste waters, they make the well casing pipes of the corrosion-resistant metal, and they cement the external annulus with the aggressive-resistant varieties of cement with the rise of it to the wellhead.