Open pit mine

Open-arc furnaces Open-celled foam Open-circuit potential Open-mold processes Open-pit mining Operating line... 

Mining. Underground mining procedures are used for deep fluorspar deposits, and open-pit mines are used for shallow deposits or where conditions do not support underground mining techniques (see Mineral RECOVERY AND PROCESSING). 

Because the ore quaUty is variable, large open-pit mining areas are first identified by general exploration specific mining strips are later identified by further exploration and testing. Surface mining methods are used. The overburden is drilled, blasted, and removed, and the waste from a given strip is dumped into a previously worked-out strip. After removal of the overburden, the exposed caUche is drilled, blasted, and loaded into 80-metric ton tmcks that dehver the ore to a transfer rail station for transportation to the plants. 

Recovery methods are based either on mining combined with some further processing or operation on the oil sands m situ (Fig. 6). The mining methods are appHcable to shallow deposits, characterized by an overburden ratio (ie, overburden depth-to-thickness of tar sand deposit) of ca 1.0. Because Athabasca tar sands have a maximum thickness of ca 90 m and average ca 45 m, there are indications that no more than 10% of the in-place deposit is mineable within 1990s concepts of the economics and technology of open-pit mining. 

Open-pit mining, and the fact that the beryUium may be extracted by leaching with sulfuric acid. Although some beryl is processed, the majority of beryUium is now obtained from bertrandite. 

Cemented carbides play a cmcial role in the recovery of metallic ores and nonmetals by underground or open-pit mining practices, recovery of minerals such as coal (qv), potash, and trona, and drilling for oh and gas. The methods of excavation can be broadly classified into three types rotary... 

Environmental assessments of open-pit mines include an understanding of geochemical processes, which control production of acidity and migration of metals (Davis Ashenberg 1998, MEND 1991). 

Diavik Diamond Mine Inc. is located on an island in Lac de Gras, 300 km northeast of Yellowknife, NT (Fig. 1).). Open pit mining will lead to the eventual development of two 200 Mt permanent stockpiles of waste rock. The country rock consists of granite averaging <0.04 wt.% S and biotite schist averaging >0.08 wt.% S. Both rock types contain low concentrations of carbonate minerals. 

The amount of solid waste depends on the method of uranium ore exploration. By deep mining, each ton of ore is supplemented by 0.2-0.3 tons of waste ores, and by open pit mining, per 1 ton of ore up to 8-10 tons of excavation materials are produced. Moreover, uranium ores contain from 5% up to 25-30% of waste ores, which are deposited as mine tails. 

Four underground mines (Pohla, Schlema, Konigstein, Gittersee) and an open pit mine coimected to underground operations (Roimeburg)... 

Uses. In section 1, we showed that most of the LOX in the USA are used in the strip mining of coal. In Europe LOX were also extensively used in open pit mining, tunneling and construction. Indeed, in the first half of this century, LOX were used in most expls applications, although not extensively, where fumes were not a problem. O Neil Van Fleet (Ref 5a) consider LOX economical and safe (See Sect 4 on LOX safety). La Magna (Ref 9) prefers LOX to Dynamites. In the last decade... 

Oil shale deposits in Estonia are exploited either in open pits (typically at a depth <30 m) or underground mines (if depth >30 m) in the ratio 47 wt% to 53 wt% (Eesti Polevkivi Ltd. 2003). The largest underground mine, the Estonia mine, reaches depths of 40-70 m the smaller Viru mine is still in operation, whereas the Ahtme mine was closed by 2002 (for locations, see Fig. 3). There are two open pit mines in operation, Narva and Aidu , with a combined production of 5.5 Mt in 2002 (Eesti Polevkivi Ltd. 2003) and yielding shales with calorific values of 8.3-9.0MJ/kg (Koel 1999). 

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