Aeration

AERATION (from the Greek word "aer" (air) * EN: aeration; DE: Beluftung, Luftwechsel, Durchluftung; FR: aeration; ES: aireacion; RU: аэрация) is the controlled air exchange or saturation of the liquids with air. Within the mining industry, aeration is performed within the open pit mines (see the "Airing of the open pit mines" article), industrial buildings (for example, the aeration of the agglomeration and beneficiation plants), and also during the hydraulic technological processes (within the settling basins of the mine, quarry, factory waste waters, systems of the preparation of the drilling fluids, and so on).

The aeration of the buildings proceeds on the account of the difference of the densities of the external and internal air, and on the account of the impact of the wind onto the walls and roofs of the buildings. The exchange of the air (thinning and outflow of the harmful substances) reaches 1 million cubic metres per hour without the expenditures of the energy for the movement of the air. The aeration of the liquids is performed during the purification of the industrial waste waters of the harmful admixtures (iron hydroxide, hydrogen sulfide, and other chemical compounds) before the discharge into the natural water bodies, during the intensification of the processes of beneficiation, sinking of the boreholes, pumping-out of the water with the help of the airlift, and so on.

They purify the waste waters of the mining enterprises of the harmful gases within the film (the flow of the water and air into the opposite directions is maintained within the apparatuses) or bubbling (the passing of the air through the liquid) degassers. The processing of the acid iron-containing mine waters is performed mainly within the step aerators, which are placed above the distribution channel of the settler. The installation is by itself the system of the overlying battens, which are situated at the distance of 0.4 metres each above the other. With the content of the Fe2+ of less than 52 milligrams per litre, they use 5 battens, with the greater content, they increase their quantity, or they perform the repeated aeration, sparging. The biological purification of the waste waters is performed by the microorganisms of the activated sludge. Waste water is continuously mixed and aerated till the saturation with the oxygen of the air. The aeration is performed by the pneumatic, mechanical, pneumatic-mechanical, and jet aerators.

The aeration of the pulp for the subsequent flotation is intensified by the reagent, which is specifically introduced into the pulp, namely, by the foaming agent, which assists to the dispersion of the air into the fine bubbles. These reagents also prevent the unification of the small bubbles into the large ones, and decrease the speed of their surfacing within the pulp, which intensifies the aeration and positively influences the flotation. Under the optimal conditions, within the mechanical flotation machines the majority of the bubbles have the diameter of 0.8-1 millimetres, and within the pneumatic ones 2.5-4 millimetres. The productivity of the machines is proportional to the volume of the aerated zone of the pulp within the chamber of the machine.

The aeration of the drilling fluids is performed during the drilling of the boreholes for the creation of the hydrodynamic equilibrium within the system of the borehole with layer, and for the plugging of the absorbing layers, decreasing of the hydrodynamic pressure onto the bottomhole and improvement of its cleaning, improvement of the quality of the unsealing of the productive layers on the account of the drilling during the mode of the depression or equilibrium. For the creation of the aerated solutions, the air (less often natural gas, nitrogen, helium) and the liquid are injected with the help of the compressors and pumps into the drilling string to the drilling bit and further to the wellhead, which is then hermetically sealed with the rotating blowout preventer. The regulation of the pressure onto the water-gas-oil-bearing layers and the walls of the borehole, and the prevention of the inflows (outbursts) of the layer (reservoir) fluids, of the collapse of the unstable rocks, are ensured on the account of the change of the flows of the liquid and gas phases, and on the account of the system of the back pressure onto the wellhead.