Open pit mining

We report, here, results for three till samples from a large regional study (McClenaghan etal. 2009) 1) 05-MPB-08, from the south shoulder of the Thompson Mine South pit, contains abundant pentlandite and chalcopyrite 2) 06-MPB-58, from a location 600 m west and down-ice (W) of the main ore zone at the Pipe Mine, contains sperrylite 3) 06-MPB-61, from the west shoulder of the Pipe Mine open pit, 200 m W (down-ice) of the ore zone, contains sperrylite. 

Plant and soil samples were collected from two areas located in the central part of the mining district (Fig. 1). Sampling was carried out especially near the old Tafone Mine open pit (now a small lake) and along a tract of the Chiarone stream, where mining works were more intensive (Fig. 3). 

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). 

The Utah deposit is located in southwestern Utah near Cedar City. The iron ore deposits are of contact metamorphic origin. The cmde ore contains 35 to 65% iron, primarily in the form of magnetite and goethite. Mining is done by the open pit method. The cmde ore is cmshed, screened at —75 mm (—200 mesh size) and shipped as lump ore containing 54% iron. The ore is rescreened at the steel mill to produce lump ore (10—64 mm) for the blast furnace and sinter feed (0—10 mm) for the sinter plant. 

Limestone Production. Because more than 99% of U.S. limestone is sold or used as cmshed and broken stone, rather than dimension-stone, most of the description of limestone s extraction and processing herein focuses on the former (Fig. 4). Most stone is obtained by open-pit quarrying methods. Underground mining is pursued by some important operations, but the toimage quarried exceeds that mined by nearly 20-fold. There is, however, a slight trend toward increased mining which should continue. 

Flake Mica. Flake mica is mined from weathered and hard rock pegmatites, granodiorite, and schist and gneiss by conventional open-pit methods. In soft, residual material, dozers, shovels, scrapers, and front-end loaders are used to mine the ore. Often kaolin, quartz, and feldspar are recovered along with the mica (see also Clays Silicon compounds). 

The former Soviet Union constmcted a 262-km, 508-mm dia experimental coal slurry line between the Belovo open-pit coal mine in Siberia s Kuznets basin to an electric power plant at Novosibirsk, using technology developed by Snamprogetti. Testing began in late 1989 and tentative plans call for constmction of two much larger slurry pipelines, each 3000-km long, with capacity to move a total of 33 x 10 t/yr to industrialized areas near the Ural Mountains (27,33). 

Canada s most productive district is in the Canadian shield at Cobalt, Ontario. Nearly 97% of the silver values in this pre-Cambrian age ore were found as great slabs of nearly pure silver. One slab was 474 kg. The huge open-pit Kidd Creek Mine has had an aimual output of over 80 t of silver. 

SQM Nitratos (Chile) operates two sodium nitrate plants in northern Chile Pedro de Valdivia and Mama Elena, about 30 km distant from one another. The caUche is mined in open-pit areas. A solar evaporation plant, Coya Sur, Hes in between. A flow sheet of the processing operations for sodium nitrate production is shown in Figure 2. 

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 zinc mining is not common, since most mines ate below the surface. The Kidd Creek Mine in Ontario, Canada, is a combination open-pit—underground mine. It is one of the richest deposits in the world with an estimated 62.5 x 10 t grading 7.08% zinc, 1.33% copper, and 151 g silver (14). Underground mining methods include room-and-pdlar, shrinkage, cut-and-fill, and square set. In the United States, ca 20 mines account for more than 98% of zinc production. 

The choice of a particular mining method depends on a number of parameters, typically the physical properties of the host matrix, the fiber content of the ore, the amount of sterile materials, the presence of contaminants, and the extent of potential fiber degradation during the various mining operations (33). However, most of the asbestos mining operations are of the open pit type, using bench drilling techniques. 

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. 

The source of Argentine production is an open-pit tincal mine at 4000 m above sea level. A modem plant is located near the mine site. Total production of sodium borates is approximately 200,000 metric tons per year (101). 

Etibank is the sole producer of boron minerals and derivatives in Turkey, which is second in production only to the United States. The open-pit Kirka mine in the Eskisehir Province is the only source of Turkish sodium borate ore. A tincal concentrate is produced from ore that has been blasted and carried in tmcks to the concentration plant. The ore is screened and cmshed to reduce it to —100 mm and then hammer milled to —25 mm. The stockpiled material is further milled and screened to 6 mm. A fraction of +1 mm (+18 mesh, U.S. Standard) is washed and classified to remove fine clay. Clay is removed from the —1 mm faction bypassing it through cyclones and then through a classifier. This material is centrifuged and combined with the washed + 1 mm faction to produce a final product which is a —6 mm concentrate having 6—8 wt % moisture and 32% 2 3 1987 production was... 

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... 

The commercial value of a clay deposit depends on market trends, competitive materials, transportation faciflties, new machinery and processes, and labor and fuel costs. Naturally exposed outcrops, geological area and stmcture maps, aerial photographs, hand and power auger drills, core drills, earth resistivity, and shallow seismic methods are used ia exploration for clays (32). Clays are mined primarily by open-pit operation, including hydraulic extraction however, underground mining is also practiced. 

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