نتایج جستجو برای: underground mines
تعداد نتایج: 20867 فیلتر نتایج به سال:
In underground mines and tunnels accurate and continuous positioning of moving machines and humans has been studied extensively. Geomagnetic field based positioning is an interesting possibility for this measurement need. Using a commercial smart phone and a new calculation service provided by a Finnish company, a feasibility and accuracy assertion tests were done in Finnish underground mine. F...
Ground subsidence monitoring is of paramount importance in relation to the safety and efficiency of underground mining operations. Moreover, in established coal fields in eastern Australia, it has become harder and harder to select underground minesites which can avoid major engineering structures both on the surface and underground (highways, bridges, buildings, abandoned workings of old under...
The presence of methane in coal mines is one of the major problems in underground coal mines. Every year, in underground coal mines, a lot of casualties due to outbursts and explosions of methane gas is occurring. Existence of this gas in the mines not only creates a difficult and dangerous situation for work but also makes it more expensive. The release of this gas to the air causes a further ...
To overcome the frequency-selective fading of ultra wide band (UWB) caused by the multi-path propagation in complicated environment of coal mines, an underground wireless communication system of UWB based on multi-band orthogonal frequency division multiplexing (MB-OFDM) for coal mine is presented. Independent angle impulse response is used to build up revised channel model for underground tunn...
A low cost, battery-operated, portable, real-time aerosol analyzer is not available for monitoring diesel particulate matter (DPM) concentrations in underground mines. This study summarizes a field evaluation conducted at an underground limestone mine to evaluate the potential of the TSI AM 510 portable photometer (equipped with a Dorr-Oliver cyclone and 1.0-mum impactor) to qualitatively track...
Radon is a naturally occurring gas that seeps out of rocks and soil. Radon comes from uranium that has been in the ground since the time the earth was formed, and the rate of radon seepage is variable, partly because the amounts of uranium in the soil vary considerably. Radon flows from the soil into outdoor air and also into the air in homes from the movement of gases in the soil beneath homes...
Mine fill is the material placed underground to fill the voids created by mining excavations. It provides overall large scale ground stabilization while allowing localized pillar recovery. In addition to providing a working floor or back, mine fill has the potential to reduce subsidence and minimize dilution. Mine fill is essential to cut and fill, benching and sublevel stoping mining methods. ...
Australia has a long history of underground mining. Even with advances in open cut mining equipment, techniques and economics, many orebodies are still best mined by underground means. In addition, modern exploration tools are ‘uncovering’ orebodies that are at increasing depths. South African mines are currently producing from below 3 km, and developing down to 5 km depths – it is likely that ...
The particle size distribution of fragmented rock in mines significantly affects operational performance of loading equipment, materials handling and crushing systems. A number of methods to measure rock fragmentation exist at present, however these systems have a number of shortcomings in an underground environment. This paper outlines the first implementation of high resolution 3D laser scann...
In recent years, Unmanned Aerial Vehicle (UAV) technology has been introduced into the mining industry to conduct terrain surveying. This work investigates the application of UAVs with artificial lighting for measurement of rock fragmentation under poor lighting conditions, representing night shifts in surface mines or working conditions in underground mines. The study relies on indoor and outd...
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