نتایج جستجو برای: surface mines
تعداد نتایج: 641844 فیلتر نتایج به سال:
In the early 1980’s, the world steel market collapsed. Since the almost exclusive use of ironore is in steel production, many iron-ore mines had to be shut down. We divide the major iron-ore producing countries into groups based on the threat of closure faced by iron-ore mines in the respective country. In countries where mines faced no threat of closure, the iron-ore industry had little or no ...
Orissa accounts for 95 percent of the chromium ore reserves of India. It increases the economic status, but adversely reduces the ecological cover. Chromite mines generate considerable quantity of pollutants containing toxic hexavalent chromium, a known carcinogen, which contaminates 10 to 4000 mg/kg (ppm) of total chromium in air, water and soil environment. Surface water and ground water in S...
Coal is the most highly used source of energy for generating power in the world. Although, it has adverse environmental impacts (Weart, 2003), it is so widely used mainly because it is relatively cheap, abundantly available and readily fits with traditional power generation technologies. It is extracted from mines using both underground and surface mining techniques – either of them having adva...
Saline waters from underground coal mines in Poland often contain natural radioactive isotopes, mainly 226Ra from the uranium decay series and 228Ra from the thorium series. More than 70% of the total amount of radium remains underground as radioactive deposits due to spontaneous co-precipitation or water treatment technologies, but several tens of MBq of 226Ra and even higher activity of 228Ra...
The origin of this report lies in the very interesting discussions with Chal-lamel of the CGES at Ecole des Mines de Paris and with Hugues Mounier of Ecole des Mines de Nantes.
We show that the Minesweeper game is PP-hard, when the object is to locate all mines with the highest probability. When the probability of locating all mines may be infinitesimal, the Minesweeper game is even PSPACE-complete. In our construction, the player can reveal a boolean circuit in polynomial time, after guessing an initial square with no surrounding mines, a guess that has 99 percent pr...
background and purpose: multiple sclerosis (ms) is a disease determined by the interaction of genetic and environmental factors. metals are suspected of being involved in ms. there is not any epidemiologic study about mines and ms. the purpose of this study was to determine ms prevalence according to mines in kerman province. methods: this cross-sectional study was conducted on 932 patients in ...
Oxidation of sulfide-containing ores is the main cause of Acid Mine Drainage (AMD), which is an environmental problem associated with both the abandoned and active mines. Iron-bearing sulfide minerals can be oxidized and form mine waters with high sulfate content, low pH, high electrical conductivity, high redox potential, and high concentrations of iron, aluminum, and other heavy metals. In th...
Concentrations of total Hg, Hg (II), and methylmercury were measured in stream-sediment, stream-water, and fish collected downstream from abandoned mercury mines in southwestern Alaska to evaluate environmental effects to surrounding ecosystems. These mines are found in a broad belt covering several tens of thousands of square kilometers, primarily in the Kuskokwim River basin. Mercury ore is d...
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