Equations
The equations for stripping ratio are,
for coal:
for metal:
where volume is typically expressed as m3 or yd and weight is typically expressed as tonne or ton.
In surface mining, stripping ratio or strip ratio refers to the amount of waste (or overburden) that must be removed to release a given ore quantity. [1] [2] It is a number or ratio that express how much waste is mined per unit of ore. The units of a stripping ratio can vary between mine types. For example, in coal mining the stripping ratio is commonly referred to as volume/weight. [3] , whereas in metal mining, stripping ratio is unitless and is expressed as weight/weight. [2] A stripping ratio can be expressed as a ratio or as a number.
The equations for stripping ratio are,
for coal:
for metal:
where volume is typically expressed as m3 or yd and weight is typically expressed as tonne or ton.
It is common for the stripping ratio to be used as an indicator of economic value for an open pit mine. [1] This is because removal of waste is a cost to the mine whereas mining ore leads to revenue. A stripping ratio is commonly used as a quick method to evaluate a mine’s or a design’s value. High stripping ratios are not desired because they are indicating that large amounts of waste must be moved to access ore.
Mining is the extraction of valuable geological materials from the Earth and other astronomical objects. Mining is required to obtain most materials that cannot be grown through agricultural processes, or feasibly created artificially in a laboratory or factory. Ores recovered by mining include metals, coal, oil shale, gemstones, limestone, chalk, dimension stone, rock salt, potash, gravel, and clay. The ore must be a rock or mineral that contains valuable constituent, can be extracted or mined and sold for profit. Mining in a wider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or even water.
Ore is natural rock or sediment that contains one or more valuable minerals concentrated above background levels, typically containing metals, that can be mined, treated and sold at a profit. The grade of ore refers to the concentration of the desired material it contains. The value of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining, and is therefore considered an ore. A complex ore is one containing more than one valuable mineral.
Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the form of magnetite (Fe
3O
4, 72.4% Fe), hematite (Fe
2O
3, 69.9% Fe), goethite (FeO(OH), 62.9% Fe), limonite (FeO(OH)·n(H2O), 55% Fe) or siderite (FeCO3, 48.2% Fe).
Coal mining is the process of extracting coal from the ground or from a mine. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United Kingdom and South Africa, a coal mine and its structures are a colliery, a coal mine is called a 'pit', and the above-ground structures are a 'pit head'. In Australia, "colliery" generally refers to an underground coal mine.
Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique of extracting rock or minerals from the earth from an open-air pit, sometimes known as a borrow.
In mining, tailings or tails are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different from overburden, which is the waste rock or other material that overlies an ore or mineral body and is displaced during mining without being processed.
Mining in the engineering discipline is the extraction of minerals from underneath, open pit, above or on the ground. Mining engineering is associated with many other disciplines, such as mineral processing, exploration, excavation, geology, and metallurgy, geotechnical engineering and surveying. A mining engineer may manage any phase of mining operations, from exploration and discovery of the mineral resources, through feasibility study, mine design, development of plans, production and operations to mine closure.
In mining, overburden is the material that lies above an area that lends itself to economical exploitation, such as the rock, soil, and ecosystem that lies above a coal seam or ore body. Overburden is distinct from tailings, the material that remains after economically valuable components have been extracted from the generally finely milled ore. Overburden is removed during surface mining, but is typically not contaminated with toxic components. Overburden may also be used to restore an exhausted mining site during reclamation.
Acid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines or coal mines.
A mill is a device, often a structure, machine or kitchen appliance, that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. There are many different types of mills and many types of materials processed in them. Historically mills were powered by hand or by animals, working animal, wind (windmill) or water (watermill). In modern era, they are usually powered by electricity.
In mining, gangue is the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. It is thus distinct from overburden, which is the waste rock or materials overlying an ore or mineral body that are displaced during mining without being processed, and from tailings, which is rock already stripped of valuable minerals.
Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. This is used in mineral processing, paper recycling and waste-water treatment industries. Historically this was first used in the mining industry, where it was one of the great enabling technologies of the 20th century. It has been described as "the single most important operation used for the recovery and upgrading of sulfide ores". The development of froth flotation has improved the recovery of valuable minerals, such as copper- and lead-bearing minerals. Along with mechanized mining, it has allowed the economic recovery of valuable metals from much lower grade ore than previously.
In the field of extractive metallurgy, mineral processing is the process of separating commercially valuable minerals from their ores. Depending on the processes used in each instance, it is often also known as ore dressing or ore milling.
Surface mining, including strip mining, open-pit mining and mountaintop removal mining, is a broad category of mining in which soil and rock overlying the mineral deposit are removed, in contrast to underground mining, in which the overlying rock is left in place, and the mineral is removed through shafts or tunnels.
There are several classification systems for the economic evaluation of mineral deposits worldwide. The most commonly used schemes base on the International Reporting Template, developed by the CRIRSCO - Committee for Mineral Reserves International Reporting Standards, like the Australian Joint Ore Reserves Committee - JORC Code 2012, the Pan-European Reserves & Resources Reporting Committee' – PERC Reporting Standard from 2021, the Canadian Institute of Mining, Metallurgy and Petroleum - CIM classification and the South African Code for the Reporting of Mineral Resources and Mineral Reserves (SAMREC). A more detailed description of the historical development concerning reporting about mineral deposits can be found on the PERC web site.
The following outline is provided as an overview of and topical guide to mining:
Environmental effects of mining can occur at local, regional, and global scales through direct and indirect mining practices. Mining can cause in erosion, sinkholes, loss of biodiversity, or the contamination of soil, groundwater, and surface water by chemicals emitted from mining processes. These processes also affect the atmosphere through carbon emissions which contributes to climate change. Some mining methods may have such significant environmental and public health effects that mining companies in some countries are required to follow strict environmental and rehabilitation codes to ensure that the mined area returns to its original state.
Cominco Resources is a private company which is developing the US$2billion Hinda phosphate project located in The Republic of the Congo. Through its subsidiary it owns 100% of the Hinda Phosphate Project, which comprises the Hinda Permit, and the Kolatchikanou Permit. The Hinda project is the world's largest undeveloped phosphate deposit with a JORC Mineral Resource of 678 Mt and a Minable Ore Reserve of 405 Mt, sufficient for over 24 years of production. Cominco Resources was merged with Kropz in December 2018 and listed on the AIM market.
A circle-throw vibrating machine is a screening machine employed in processes involving particle separation. In particle processes screening refers to separation of larger from smaller particles in a given feed, using only the materials' physical properties. Circle throw machines have simple structure with high screening efficiency and volume. However it has limitations on the types of feed that can be processed smoothly. Some characteristics of circle-throw machines, such as frequency, vibration amplitude and angle of incline deck also affect output.
Mineral resource estimation is used to determine and define the ore tonnage and grade of a geological deposit, from the developed block model. There are different estimation methods used for different scenarios dependent upon the ore boundaries, geological deposit geometry, grade variability and the amount of time and money available. A typical resource estimation involves the construction of a geological and resource model with data from various sources. Depending on the nature of the information and whether the data is hard copy or computerized, the principal steps of computer resource estimation are:
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