Optimization of the ventilation scheme for increasing production capacity of underground mines

Currently, many underground mines are revising their design solutions to increase their production capacity. This tendency is explained by the decreasing ore grades, as well as by the extensive introduction of mechanization in underground mining operations that has improved the output of mobile equipment by increasing the box capacity and engine power. Dieselpowered mobile vehicles are the most common in underground mining practice. The advantages of such engines are obvious as they generate more power than other types of engines. However, the high air demand for mine ventilation limits their application. This is associated with the need to increase the cross-sections of permanent mine workings in order to comply with the standard air flow rate with account of the increased ventilation capacity along with an increase in the inventory of mobile equipment in order to ensure the specified output of the mine. The specific features of mining operations are defined by the stage-wise character of commissioning various blocks of the deposit. Managing of production and development works provides an opportunity to ventilate the mine sections due to their consecutive commissioning, locally, with an isolated stream of air by means of mine workings that do not have the intersection of air streams. This provides a reduction of critical path of air travel up to 30% and reduction of the general mine ventilating pressure drop by at least 20% at constant air flow rate. The results of the work can be used in designing the ventilation system of underground mines both under construction and in operation.

Experimental Research of Gaseous Emissions Impact on the Performance of New-Design Cylindrical Multi-Channel Cyclone with Adjustable Half-Rings

Cyclones are widely used for separating particles from gas in energy production objects. The efficiency of conventional centrifugal air cleaning devices ranges from 85 to 90%, but the weakness of many cyclones is the low collection efficiency of particles less than 10 μm in diameter. The novelty of this work is the research of the channel-type treatment device, with few levels adapted for precipitation of fine particulate matter, acting by a centrifugal and filtration principle. Many factors have an impact on cyclone efficiency—humidity, temperature, gas (air) composition, airflow velocity and etc. Many scientists evaluated only the effect of origin and size of PM on cyclone efficiency. The effect of gas (air) composition and temperature, and humidity on the multi-channel cyclone-separator efficiency still demands contributions. Complex theoretical and experimental research on air flow parameters and the efficiency of a cylindrical eight-channel system with adjustable half-rings for removing fine-dispersive particles (<20 μm) was carried out. The impact of air humidity and temperature on air flow, and gaseous smoke components on the removal of wood ashes was analyzed. The dusty gas flow was regulated. During the experiment, the average velocity of the cyclone was 16 m/s, and the temperature was 20–50 °C. The current paper presents experimental research results of wood ash removal in an eight-channel cyclone and theoretical methodology for the calculation of airflow parameters and cyclone effectiveness.

Effect of an Electric Field on an Optical Breakdown in the Air Stream

Experimental data on the effect of an electric field on the plasma of an optical discharge in an air flow have been obtained. Two configurations of an external electric field under the action of an optical discharge on the plasma are considered. To create an electric field, flat (the field along the beam and across the flow) and ring electrodes (the field across the laser beam and along the flow) were used. It was found that there are two modes of combined discharge (optical and electrical). When the field was created symmetrically with respect to the flow axis, an electrical breakdown was observed from the nozzle exit (positively charged electrode) to the focusing point of the laser beam, while no streamers were observed in the optical discharge wake. In another case, an electric discharge is realized between flat electrodes simultaneously with optical breakdown. In a field of constant strength above 3 kV/cm, the presence of an optical discharge plasma promoted electrical breakdown of the medium. In this case, the parameters of the electrical breakdown depended on the shape of the electrodes, the polarity of the applied voltage, and the air flow rate.