Worldwide, consumption of raw materials and especially coal is increasing. For underground coal mining there are necessary mine networks reaching higher and higher depths. Associated to mine networks, mine ventilation networks exist having vital role in ensuring optimal microclimate conditions. Presently, every field of industry is using the computers at every production stage. Mining or mineral industry is not an exception. Today, due the great extent of the underground networks and the amount of data involved, we are using computers in solving problems of planning and design, engineering and control of mine atmospheric environment. The solving of a complex ventilation network of a mine cannot be done manually, and usage of a specialized software and advanced IT equipment is a must. One of the most advanced specialized software is VENTSIM Visual Advanced, developed in Australia. The software has been used by the authors for modeling and solving of two complex ventilation networks related to Lupeni and Uricani Mines. The concrete result consists in the accurate solving of natural repartition of the air flows at the branch level, based on automatic calculation of their lengths. Another important advantage offered by the application consists in 3-D solid visualization, allowing user to obtain any technical detail, from any angle.

In the process of underground coal mining a complex network of vertical, horizontal and inclined mine workings with the purpose of extraction, transportation and evacuation to the surface are utilized. The mining workings are also being utilized for ventilation network system, which is also used for ensuring the oxygen supply necessary for workers, as well for diluting explosive gases and/or toxic substances and, ultimately, for exhausting the heat resulted from underground workings. For air flow pumping, special fans, of high capacity, located at the surface of the main ventilation stations are used. The fan operating mode depends on aerodynamic parameters and also on the structure of the ventilation network. Knowledge of specific local network parameters leads to the optimization of air flow distribution. The novelty presented in the paper consists in analysing and optimising the complex ventilation networks of Lonea mining unit, based on the depresiometric, flowmeters measurements and the status parameters specifics to each branch. Worldwide, in high developed mining countries, solving a complex ventilation networks it's being carried out with the help of specialized software such as VentSim, VentGraft, VentPri, 3D Canvent etc., through discontinuous operating at the mining unit quarter or to a distant location, where upon the results obtained are presented to the ventilation specialists. The complex ventilation network afferent to Lonea mining unit was rendered, fixed and optimised, up-to-date, using 3D Canvent software.

Methane gas accompanying coal deposits was formed as a result of successive stages of the anaerobic process of vegetal material transformation into coal, at high temperatures and pressures, without external oxygen supply. During the metamorphism process, the content of C, H and O is modified, meaning an increase in carbon content, a decrease in hydrogen and oxygen, the nitrogen and sulphur content remaining constant. During this process, water and carbon dioxide is generated, the water being generated in the first transformation phases. Within the slow oxidation process, gas products result by using the oxygen content in plants, especially methane and carbon dioxide due to the fermentation stimulated by bacteria. Methane released into the atmosphere following the mining of coal have double ecological impact, participating in the destruction of the ozone layer and at the same time contributing to the enhancement of the greenhouse effect. At the same time, methane gas released into the atmosphere during coal mining may be used by mining operators as primary power resource for covering the power requirements of the mine or it can be used for commercial purposes.

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