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134-469: 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. The extraction of minerals from ore can be done two ways: placer mining , which uses water and gravity to concentrate

268-458: A titrant . In freshwater , particularly those on non- limestone terrains, alkalinities are low and involve a lot of ions. In the ocean, on the other hand, alkalinity is completely dominated by carbonate and bicarbonate plus a small contribution from borate . Although alkalinity is primarily a term used by limnologists and oceanographers , it is also used by hydrologists to describe temporary hardness . Moreover, measuring alkalinity

402-472: A byproduct of oxidation reactions. The ocean's alkalinity varies over time, most significantly over geologic timescales (millennia). Changes in the balance between terrestrial weathering and sedimentation of carbonate minerals (for example, as a function of ocean acidification) are the primary long-term drivers of alkalinity in the ocean. Over human timescales, mean ocean alkalinity is relatively stable. Seasonal and annual variability of mean ocean alkalinity

536-465: A concern as well, and where enforced, modern practices have significantly improved safety in mines. Unregulated, poorly regulated or illegal mining , especially in developing economies , frequently contributes to local human rights violations and environmental conflicts . Mining can also perpetuate political instability through resource conflicts . Since the beginning of civilization, people have used stone , clay and, later, metals found close to

670-636: A hopper and a shaking screen or trommel which frees the desired minerals from the waste gravel. The minerals are then concentrated using sluices or jigs. Large drills are used to sink shafts, excavate stopes, and obtain samples for analysis. Trams are used to transport miners, minerals and waste. Lifts carry miners into and out of mines, and move rock and ore out, and machinery in and out, of underground mines. Huge trucks, shovels and cranes are employed in surface mining to move large quantities of overburden and ore. Processing plants use large crushers, mills, reactors, roasters and other equipment to consolidate

804-406: A low percent of solids and relatively high water content (normally ranging from 20% to 60% solids for most hard rock mining) and when deposited into the tailings pond the solids and liquids separate. In paste tailings the percent of solids in the tailings slurry is increased through the use of paste thickeners to produce a product where the minimal separation of water and solids occurs and the material

938-883: A mass of actual rock. Both types of ore deposit, placer or lode, are mined by both surface and underground methods. Some mining, including much of the rare earth elements and uranium mining , is done by less-common methods, such as in-situ leaching : this technique involves digging neither at the surface nor underground. The extraction of target minerals by this technique requires that they be soluble, e.g., potash , potassium chloride , sodium chloride , sodium sulfate , which dissolve in water. Some minerals, such as copper minerals and uranium oxide , require acid or carbonate solutions to dissolve. Explosives in Mining Explosives have been used in surface mining and sub-surface mining to blast out rock and ore intended for processing. The most common explosive used in mining

1072-426: A mining operation. Once the analysis determines a given ore body is worth recovering, development begins to create access to the ore body. The mine buildings and processing plants are built, and any necessary equipment is obtained. The operation of the mine to recover the ore begins and continues as long as the company operating the mine finds it economical to do so. Once all the ore that the mine can produce profitably

1206-503: A more sustainable future, the demand for metals is set to skyrocket. Between 2022 and 2050, an estimated 7 billion metric tons of metals will need to be extracted. Steel will account for the largest portion of this total at 5 billion tons, followed by aluminum at 950 million tons, copper at 650 million tons, graphite at 170 million tons, nickel at 100 million tons, and other metals. Notably, the energy expenditure required to extract these metals will soon surpass that of coal mining, highlighting

1340-416: A much greater impact on oceanic alkalinity on short (minutes to centuries) timescales. Denitrification and sulfate reduction occur in oxygen-limited environments. Both of these processes consume hydrogen ions (thus increasing alkalinity) and release gases (N 2 or H 2 S), which eventually escape into the atmosphere. Nitrification and sulfide oxidation both decrease alkalinity by releasing protons as

1474-445: A neutral species, thus increasing alkalinity by one per equivalent. CO 3 however, will consume two protons before becoming a zero-level species (CO 2 ), thus it increases alkalinity by two per mole of CO 3 . [H ] and [ HSO 4 ] decrease alkalinity, as they act as sources of protons. They are often represented collectively as [H ] T . Alkalinity is typically reported as mg/L as CaCO 3 . (The conjunction "as"

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1608-446: A pipeline then discharged so as to eventually descend into the depths. Practically, it is not an ideal method, as the close proximity to off-shelf depths is rare. When STD is used, the depth of discharge is often comparatively shallow, and extensive damage to the seafloor can result due to covering by the tailings product. If the density and temperature of the tailings product is not controlled, it may travel long distances, or even float to

1742-581: A source of acid drainage , leading to the need for permanent monitoring and treatment of water passing through the tailings dam; the cost of mine cleanup has typically been 10 times that of mining industry estimates when acid drainage was involved. The greatest danger of tailings ponds is dam failure, with the most publicized failure in the U.S. being the failure of a coal slurry dam in the West Virginia Buffalo Creek Flood of 1972, which killed 125 people; other collapses include

1876-408: A strong inducement to extract these metals or to lease the deposits and collect royalties from mine operators. English, German , and Dutch capital combined to finance extraction and refining . Hundreds of German technicians and skilled workers were brought over; in 1642 a colony of 4,000 foreigners was mining and smelting copper at Keswick in the northwestern mountains. Use of water power in

2010-436: A virtually limitless number of species that contribute to alkalinity. Alkalinity is frequently given as molar equivalents per liter of solution or per kilogram of solvent. In commercial (e.g. the swimming pool industry) and regulatory contexts, alkalinity might also be given in parts per million of equivalent calcium carbonate (ppm CaCO 3 ) . Alkalinity is sometimes incorrectly used interchangeably with basicity . For example,

2144-651: Is ammonium nitrate . Between 1870 and 1920, in Queensland Australia, an increase in mining accidents lead to more safety measures surrounding the use of explosives for mining. In the United States of America, between 1990 and 1999, about 22.3 billion kilograms of explosives were used in mining quarrying and other industries; Moreover " coal mining used 66.4%, nonmetal mining and quarrying 13.5%, metal mining 10.4%, construction 7.1%, and all other users 2.6%". Artisanal and small-scale mining (ASM)

2278-433: Is HDPF – High Density Paste Fill. HDPF is a more expensive method of tailings disposal than pond storage, however it has many other benefits – not just environmental but it can significantly increase the stability of underground excavations by providing a means for ground stress to be transmitted across voids – rather than having to pass around them – which can cause mining induced seismic events like that suffered previously at

2412-811: Is a blanket term for a type of subsistence mining involving a miner who may or may not be officially employed by a mining company but works independently, mining minerals using their own resources, usually by hand. While there is no completely coherent definition for ASM, artisanal mining generally includes miners who are not officially employed by a mining company and use their own resources to mine. As such, they are part of an informal economy . ASM also includes, in small-scale mining, enterprises or individuals that employ workers for mining, but who generally still use similar manually-intensive methods as artisanal miners (such as working with hand tools). In addition, ASM can be characterized as distinct from large-scale mining (LSM) by less efficient extraction of pure minerals from

2546-566: Is a growing use of the practice of dewatering tailings using vacuum or pressure filters so the tailings can then be stacked. This saves water which potentially reduces the impacts on the environment in terms of a reduction in the potential seepage rates, space used, leaves the tailings in a dense and stable arrangement and eliminates the long-term liability that ponds leave after mining is finished. However although there are potential merits to dry stacked tailings these systems are often cost prohibitive due to increased capital cost to purchase and install

2680-544: Is appropriate in this case because the alkalinity results from a mixture of ions but is reported "as if" all of this is due to CaCO 3 .) This can be converted into milliequivalents per Liter (meq/L) by dividing by 50 (the approximate MW of CaCO 3 divided by 2). Addition (or removal) of CO 2 to a solution does not change its alkalinity, since the net reaction produces the same number of equivalents of positively contributing species (H ) as negative contributing species ( HCO 3 and/or CO 3 ). Adding CO 2 to

2814-404: Is based upon the charge balance of ions in a solution. Certain ions, including Na , K , Ca , Mg , Cl , SO 4 , and NO 3 are " conservative " such that they are unaffected by changes in temperature, pressure or pH. Others such as HCO 3 are affected by changes in pH, temperature, and pressure. By isolating the conservative ions on one side of this charge balance equation,

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2948-449: Is composed of CaCO 3 and its dissociation will add Ca and CO 3 into solution. Ca will not influence alkalinity, but CO 3 will increase alkalinity by 2 units. Increased dissolution of carbonate rock by acidification from acid rain and mining has contributed to increased alkalinity concentrations in some major rivers throughout the eastern U.S. The following reaction shows how acid rain, containing sulfuric acid, can have

3082-506: Is dependent on investment, labor, energy, refining, and transportation cost. Mining operations can create a negative environmental impact, both during the mining activity and after the mine has closed. Hence, most of the world's nations have passed regulations to decrease the impact; however, the outsized role of mining in generating business for often rural, remote or economically depressed communities means that governments often fail to fully enforce such regulations. Work safety has long been

3216-408: Is deposited into a storage area as a paste (with a consistency somewhat like toothpaste). Paste tailings has the advantage that more water is recycled in the processing plant and therefore the process is more water efficient than conventional tailings and there is a lower potential for seepage. However the cost of the thickening is generally higher than for conventional tailings and the pumping costs for

3350-476: Is done by removing surface vegetation, dirt, and bedrock to reach buried ore deposits. Techniques of surface mining include: open-pit mining , which is the recovery of materials from an open pit in the ground; quarrying , identical to open-pit mining except that it refers to sand, stone and clay; strip mining , which consists of stripping surface layers off to reveal ore underneath; and mountaintop removal , commonly associated with coal mining, which involves taking

3484-468: Is equal to [ HCO 3 ] + 2[ CO 3 ] is also approximately equal to the total alkalinity in surface water. Alkalinity measures the ability of a solution to neutralize acids to the equivalence point of carbonate or bicarbonate, defined as pH 4.5 for many oceanographic/limnological studies. The alkalinity is equal to the stoichiometric sum of the bases in solution. In most Earth surface waters carbonate alkalinity tends to make up most of

3618-437: Is important in determining a stream's ability to neutralize acidic pollution from rainfall or wastewater . It is one of the best measures of the sensitivity of the stream to acid inputs. There can be long-term changes in the alkalinity of streams and rivers in response to human disturbances such as acid rain generated by SO x and NO x emissions. In 1884, Professor Wilhelm (William) Dittmar of Anderson College, now

3752-400: Is low. If this alkaline groundwater later comes into contact with the atmosphere, it can lose CO 2 , precipitate carbonate, and thereby become less alkaline again. When carbonate minerals, water, and the atmosphere are all in equilibrium, the reversible reaction shows that pH will be related to calcium ion concentration, with lower pH going with higher calcium ion concentration. In this case,

3886-613: Is mining upward, creating a sloping underground room, long wall mining , which is grinding a long ore surface underground, and room and pillar mining, which is removing ore from rooms while leaving pillars in place to support the roof of the room. Room and pillar mining often leads to retreat mining , in which supporting pillars are removed as miners retreat, allowing the room to cave in, thereby loosening more ore. Additional sub-surface mining methods include hard rock mining , bore hole mining, drift and fill mining, long hole slope mining, sub level caving, and block caving . Heavy machinery

4020-484: Is much more common, and produces, for example, 85% of minerals (excluding petroleum and natural gas) in the United States, including 98% of metallic ores. Targets are divided into two general categories of materials: placer deposits , consisting of valuable minerals contained within river gravels, beach sands, and other unconsolidated materials ; and lode deposits , where valuable minerals are found in veins, in layers, or in mineral grains generally distributed throughout

4154-413: Is not of immediate interest to the miner. The total movement of ore and waste constitutes the mining process. Often more waste than ore is mined during the life of a mine, depending on the nature and location of the ore body. Waste removal and placement is a major cost to the mining operator, so a detailed characterization of the waste material forms an essential part of the geological exploration program for

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4288-518: Is often inversely proportional to sea surface temperature (SST). Therefore, it generally increases with high latitudes and depths. As a result, upwelling areas (where water from the deep ocean is pushed to the surface) also have higher alkalinity values. There are many programs to measure, record, and study oceanic alkalinity, together with many of the other characteristics of seawater, like temperature and salinity. These include: GEOSECS (Geochemical Ocean Sections Study), TTO/NAS (Transient Tracers in

4422-460: Is radioactive due to the presence of naturally occurring uranium and thorium , and their daughter isotopes . Depending on the price achievable on the uranium market , extraction of the uranium content may be economically lucrative even absent other incentives, such as reducing the harm the radioactive heavy metals do to the environment. Bauxite tailings is a waste product generated in the industrial production of aluminium . Making provision for

4556-584: Is recovered, reclamation can begin, to make the land used by the mine suitable for future use. Technical and economic challenges notwithstanding, successful mine development must also address human factors. Working conditions are paramount to success, especially with regard to exposures to dusts, radiation, noise, explosives hazards, and vibration, as well as illumination standards. Mining today increasingly must address environmental and community impacts, including psychological and sociological dimensions. Thus, mining educator Frank T. M. White (1909–1971), broadened

4690-420: Is required to identify and address those that are most at risk from a tailings facility or its potential failure." Historically, tailings were disposed of in the most convenient manner, such as in downstream running water or down drains . Because of concerns about these sediments in the water and other issues, tailings ponds came into use. The sustainability challenge in the management of tailings and waste rock

4824-656: Is the largest producer of diamonds in Africa, with an estimated 12 million carats in 2019. Other types of mining reserves in Africa include cobalt , bauxite , iron ore , coal, and copper . Gold and coal mining started in Australia and New Zealand in the 19th century. Nickel has become important in the economy of New Caledonia . In Fiji , in 1934, the Emperor Gold Mining Company Ltd. established operations at Vatukoula , followed in 1935 by

4958-434: Is the material left over from coal mining, usually as tailings piles or spoil tips . For every tonne of hard coal generated by mining, 400 kg (880 lb) of waste material remains, which includes some lost coal that is partially economically recoverable. Coal refuse is distinct from the byproducts of burning coal, such as fly ash . Piles of coal refuse can have significant negative environmental consequences, including

5092-423: Is to conduct a feasibility study to evaluate the financial viability, the technical and financial risks, and the robustness of the project. This is when the mining company makes the decision whether to develop the mine or to walk away from the project. This includes mine planning to evaluate the economically recoverable portion of the deposit, the metallurgy and ore recoverability, marketability and payability of

5226-421: Is to dispose of material, such that it is inert or, if not, stable and contained, to minimise water and energy inputs and the surface footprint of wastes and to move toward finding alternate uses. Bounded by impoundments (an impoundment is a dam), these dams typically use "local materials" including the tailings themselves, and may be considered embankment dams . Traditionally, the only option for tailings storage

5360-419: Is used in mining to explore and develop sites, to remove and stockpile overburden, to break and remove rocks of various hardness and toughness, to process the ore, and to carry out reclamation projects after the mine is closed. Bulldozers, drills, explosives and trucks are all necessary for excavating the land. In the case of placer mining , unconsolidated gravel, or alluvium , is fed into machinery consisting of

5494-529: Is very low. Alkalinity varies by location depending on evaporation/precipitation, advection of water, biological processes, and geochemical processes. River dominated mixing also occurs close to the shore; it is strongest close to the mouth of a large river. Here, the rivers can act as either a source or a sink of alkalinity. A T follows the outflow of the river and has a linear relationship with salinity. Oceanic alkalinity also follows general trends based on latitude and depth. It has been shown that A T

Tailings - Misplaced Pages Continue

5628-768: The Beaconsfield Mine Disaster . Usually called RTD – Riverine Tailings Disposal. In most environments, not a particularly environmentally sound practice, it has seen significant utilisation in the past, leading to such spectacular environmental damage as done by the Mount Lyell Mining and Railway Company in Tasmania to the King River , or the poisoning from the Panguna mine on Bougainville Island , which led to large-scale civil unrest on

5762-521: The Greek author Diodorus Siculus , who mentions fire-setting as one method used to break down the hard rock holding the gold . One of the complexes is shown in one of the earliest known mining maps. The miners crushed the ore and ground it to a fine powder before washing the powder for the gold dust known as the dry and wet attachment processes. Mining in Europe has a very long history. Examples include

5896-756: The Ok Tedi environmental disaster in New Guinea , which destroyed the fishery of the Ok Tedi River . On average, worldwide, there is one big accident involving a tailings dam each year. Other disasters caused by tailings dam failures are, the 2000 Baia Mare cyanide spill and the Ajka alumina plant accident . In 2015, the iron ore tailings dam failure at the Germano mine complex in Minas Gerais, Brazil,

6030-516: The Principles for Responsible Investment . Mining Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials, and final reclamation or restoration of the land after the mine is closed. Mining materials are often obtained from ore bodies, lodes , veins , seams , reefs , or placer deposits . The exploitation of these deposits for raw materials

6164-572: The University of Strathclyde , analysed 77 pristine seawater samples from around the world brought back by the Challenger expedition . He found that in seawater the major ions were in a fixed ratio, confirming the hypothesis of Johan Georg Forchhammer , that is now known as the Principle of Constant Proportions. However, there was one exception. Dittmar found that the concentration of calcium

6298-452: The archaea , bacteria , and the gas released from tailings ponds showed that those were methanogens . As the depth increased, the moles of CH 4 released actually decreased. Siddique (2006, 2007) states that methanogens in the tailings pond live and reproduce by anaerobic degradation, which will lower the molecular weight from naphtha to aliphatic , aromatic hydrocarbons, carbon dioxide and methane. Those archaea and bacteria can degrade

6432-517: The argentiferous galena in the mines of Cartagena ( Cartago Nova ), Linares ( Castulo ), Plasenzuela and Azuaga , among many others. Spain was one of the most important mining regions, but all regions of the Roman Empire were exploited. In Great Britain the natives had mined minerals for millennia , but after the Roman conquest , the scale of the operations increased dramatically, as

6566-836: The greenstone of the Langdale axe industry based in the English Lake District . The oldest-known mine on archaeological record is the Ngwenya Mine in Eswatini (Swaziland) , which radiocarbon dating shows to be about 43,000 years old. At this site Paleolithic humans mined hematite to make the red pigment ochre . Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools. Ancient Egyptians mined malachite at Maadi . At first, Egyptians used

6700-408: The ocean . Perhaps the most well known is the dissolution of calcium carbonate to form Ca and CO 3 (carbonate). The carbonate ion has the potential to absorb two hydrogen ions. Therefore, it causes a net increase in ocean alkalinity. Calcium carbonate dissolution occurs in regions of the ocean which are undersaturated with respect to calcium carbonate. The increasing carbon dioxide level in

6834-509: The 21st century begins, a globalized mining industry of large multinational corporations has arisen. Peak minerals and environmental impacts have also become a concern. Different elements, particularly rare-earth minerals , have begun to increase in demand as a result of new technologies. In 2023, 8.5 billion metric tons of coal were extracted from the Earth's crust. However, as the global economy transitions away from fossil fuels and toward

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6968-680: The 7th century to the 14th century. Gold was often traded to Mediterranean economies that demanded gold and could supply salt , even though much of Africa was abundant with salt due to the mines and resources in the Sahara desert . The trading of gold for salt was mostly used to promote trade between the different economies. Since the Great Trek in the 19th century, after, gold and diamond mining in Southern Africa has had major political and economic impacts. The Democratic Republic of Congo

7102-522: The CO 2 equivalence point where the major component in water is dissolved CO 2 which is converted to H 2 CO 3 in an aqueous solution. There are no strong acids or bases at this point. Therefore, the alkalinity is modeled and quantified with respect to the CO 2 equivalence point. Because the alkalinity is measured with respect to the CO 2 equivalence point, the dissolution of CO 2 , although it adds acid and dissolved inorganic carbon, does not change

7236-524: The Earth's surface. These were used to make early tools and weapons; for example, high quality flint found in northern France , southern England and Poland was used to create flint tools . Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries. The mines at Grimes Graves and Krzemionki are especially famous, and like most other flint mines, are Neolithic in origin (c. 4000–3000 BC). Other hard rocks mined or collected for axes included

7370-617: The Elkview Mine in British Columbia. During extraction of the oil from oil sand, tailings consisting of water, silt, clays and other solvents are also created. This solid will become mature fine tailings by gravity. Foght et al (1985) estimated that there are 10 anaerobic heterotrophs and 10 sulfate-reducing prokaryotes per milliliter in the tailings pond, based on conventional most probable number methods. Foght set up an experiment with two tailings ponds and an analysis of

7504-675: The French crown to operate mines in 1733, becoming "the first practical miner on Lake Superior"; seven years later, mining was halted by an outbreak between Sioux and Chippewa tribes. Mining in the United States became widespread in the 19th century, and the United States Congress passed the General Mining Act of 1872 to encourage mining of federal lands. As with the California Gold Rush in

7638-643: The Loloma Gold Mines, N.L., and then by Fiji Mines Development Ltd. (aka Dolphin Mines Ltd.). These developments ushered in a “mining boom”, with gold production rising more than a hundred-fold, from 931.4 oz in 1934 to 107,788.5 oz in 1939, an order of magnitude then comparable to the combined output of New Zealand and Australia's eastern states. During prehistoric times, early Americans mined large amounts of copper along Lake Superior 's Keweenaw Peninsula and in nearby Isle Royale ; metallic copper

7772-551: The PET4K Processing Plant has been used in a variety of countries for the past 20 years to remediate contaminated tailings. The UN and business communities developed an international standard for tailings management in 2020 after the critical failure of the Brumadinho dam disaster . The program was convened by United Nations Environment Programme (UNEP), International Council on Mining and Metals (ICMM) and

7906-505: The Porgera Gold Mine is focusing on developing a method of combining tailings products with coarse waste rock and waste muds to create a product that can be stored on the surface in generic-looking waste dumps or stockpiles. This would allow the current use of riverine disposal to cease. Considerable work remains to be done. However, co-disposal has been successfully implemented by several designers including AMEC at, for example,

8040-481: The Romans needed Britannia 's resources, especially gold , silver , tin , and lead . Roman techniques were not limited to surface mining. They followed the ore veins underground once opencast mining was no longer feasible. At Dolaucothi they stoped out the veins and drove adits through bare rock to drain the stopes. The same adits were also used to ventilate the workings, especially important when fire-setting

8174-598: The Spanish to pulverize ore after being mined. This device was powered by animals and used the same principles used for grain threshing . Much of the knowledge of medieval mining techniques comes from books such as Biringuccio 's De la pirotechnia and probably most importantly from Georg Agricola 's De re metallica (1556). These books detail many different mining methods used in German and Saxon mines. A prime issue in medieval mines, which Agricola explains in detail,

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8308-756: The Umm el-Sawwan site; gypsum was used to make funerary items for private tombs. Other minerals mined in Egypt from the Old Kingdom (2649-2134 BC) until the Roman Period (30 BC-AD 395) including granite , sandstone , limestone , basalt , travertine , gneiss , galena , and amethyst . Mining in Egypt occurred in the earliest dynasties. The gold mines of Nubia were among the largest and most extensive of any in Ancient Egypt. These mines are described by

8442-439: The addition of CO 2 lowers the pH of a solution, thus reducing basicity while alkalinity remains unchanged ( see example below ). A variety of titrants , endpoints, and indicators are specified for various alkalinity measurement methods. Hydrochloric and sulfuric acids are common acid titrants, while phenolpthalein , methyl red , and bromocresol green are common indicators. In typical groundwater or seawater ,

8576-412: The alkalinity. In natural conditions, the dissolution of basic rocks and addition of ammonia [NH 3 ] or organic amines leads to the addition of base to natural waters at the CO 2 equivalence point. The dissolved base in water increases the pH and titrates an equivalent amount of CO 2 to bicarbonate ion and carbonate ion. At equilibrium, the water contains a certain amount of alkalinity contributed by

8710-523: The alumina produced globally is through the Bayer process; for every tonne (2,200 lb) of alumina produced, approximately 1 to 1.5 tonnes (2,200 to 3,300 lb) of red mud are also produced; the global average is 1.23. Annual production of alumina in 2023 was over 142 million tonnes (310 billion pounds) resulting in the generation of approximately 170 million tonnes (370 billion pounds) of red mud. Due to this high level of production and

8844-497: The approximately 70 million tonnes (150 billion pounds) that is produced annually is one of the most significant problems for the aluminium mining industry. Red mud , now more frequently termed bauxite residue, is an industrial waste generated during the processing of bauxite into alumina using the Bayer process . It is composed of various oxide compounds, including the iron oxides which give its red colour. Over 97% of

8978-402: The archaea and bacteria metabolize and release bubbles within the tailings, the pore water can go through the soil easily. Since they accelerate the densification of mature fine tailings, the tailings ponds are enabled to settle the solids more quickly so that the tailings can be reclaimed earlier. Moreover, the water released from the tailings can be used in the procedure of refining oil. Reducing

9112-424: The atmosphere , due to carbon dioxide emissions , results in increasing absorption of CO 2 from the atmosphere into the oceans. This does not affect the ocean's alkalinity but it does result in a reduction in pH value (called ocean acidification ). Ocean alkalinity enhancement has been proposed as one option to add alkalinity to the ocean and therefore buffer against pH changes. Biological processes have

9246-528: The bright green malachite stones for ornamentations and pottery . Later, between 2613 and 2494 BC, large building projects required expeditions abroad to the area of Wadi Maghareh in order to secure minerals and other resources not available in Egypt itself. Quarries for turquoise and copper were also found at Wadi Hammamat , Tura , Aswan and various other Nubian sites on the Sinai Peninsula and at Timna . Quarries for gypsum were found at

9380-412: The concentration of weak acid anions. Conversely, the addition of acid converts weak acid anions to CO 2 and continuous addition of strong acids can cause the alkalinity to become less than zero. For example, the following reactions take place during the addition of acid to a typical seawater solution: It can be seen from the above protonation reactions that most bases consume one proton (H ) to become

9514-417: The cutter-head is progressively launched further into the coal seam. High wall mining can produce thousands of tons of coal in contour-strip operations with narrow benches, previously mined areas, trench mine applications and steep-dip seams. Sub-surface mining consists of digging tunnels or shafts into the earth to reach buried ore deposits. Ore, for processing, and waste rock, for disposal, are brought to

9648-614: The dams, causing environmental disasters , such as the Mount Polley disaster in British Columbia . Because of these and other environmental concerns such as groundwater leakage , toxic emissions and bird death, tailing piles and ponds have received more scrutiny, especially in developed countries, but the first UN-level standard for tailing management was only established 2020. There are a wide range of methods for recovering economic value, containing or otherwise mitigating

9782-482: The demand of water can also protect the environment from drought. As mining techniques and the price of minerals improve, it is not unusual for tailings to be reprocessed using new methods, or more thoroughly with old methods, to recover additional minerals. Extensive tailings dumps of Kalgoorlie / Boulder in Western Australia were re-processed profitably in the 1990s by KalTails Mining. A machine called

9916-409: The effect of increasing river alkalinity by increasing the amount of bicarbonate ion: Another way of writing this is: The lower the pH, the higher the concentration of bicarbonate will be. This shows how a lower pH can lead to higher alkalinity if the amount of bicarbonate produced is greater than the amount of H remaining after the reaction. This is the case since the amount of acid in the rainwater

10050-490: The filter systems and the increase in operating costs (generally associated electricity consumption and consumables such as filter cloth) of such systems. While disposal into exhausted open pits is generally a straightforward operation, disposal into underground voids is more complex. A common modern approach is to mix a certain quantity of tailings with waste aggregate and cement, creating a product that can be used to backfill underground voids and stopes . A common term for this

10184-698: The focus to the “total environment of mining”, including reference to community development around mining, and how mining is portrayed to an urban society, which depends on the industry, although seemingly unaware of this dependency. He stated, “[I]n the past, mining engineers have not been called upon to study the psychological, sociological and personal problems of their own industry – aspects that nowadays are assuming tremendous importance. The mining engineer must rapidly expand his knowledge and his influence into these newer fields.” Mining techniques can be divided into two common excavation types: surface mining and sub-surface (underground) mining . Today, surface mining

10318-487: The form of water mills was extensive. The water mills were employed in crushing ore, raising ore from shafts, and ventilating galleries by powering giant bellows . Black powder was first used in mining in Selmecbánya , Kingdom of Hungary (now Banská Štiavnica , Slovakia) in 1627. Black powder allowed blasting of rock and earth to loosen and reveal ore veins. Blasting was much faster than fire-setting and allowed

10452-471: The ground. Large earthen dams may be constructed and then filled with the tailings. Exhausted open pit mines may be refilled with tailings. In all instances, due consideration must be made to contamination of the underlying water table, amongst other issues. Dewatering is an important part of pond storage, as the tailings are added to the storage facility the water is removed – usually by draining into decant tower structures. The water removed can thus be reused in

10586-400: The growing importance of sustainable metal extraction practices. The process of mining from discovery of an ore body through extraction of minerals and finally to returning the land to its natural state consists of several distinct steps. The first is discovery of the ore body, which is carried out through prospecting or exploration to find and then define the extent, location and value of

10720-428: The higher the pH, the more bicarbonate and carbonate ion there will be, in contrast to the paradoxical situation described above, where one does not have equilibrium with the atmosphere. In the ocean, alkalinity is completely dominated by carbonate and bicarbonate plus a small contribution from borate . Thus the chemical equation for alkalinity in seawater is: There are many methods of alkalinity generation in

10854-510: The impacts of tailings. However, internationally, these practices are poor, sometimes violating human rights. Tailings are also called mine dumps , culm dumps , slimes , refuse , leach residue , slickens , or terra-cone (terrikon) . The effluent from the tailings from the mining of sulfidic minerals has been described as "the largest environmental liability of the mining industry". These tailings contain large amounts of pyrite (FeS 2 ) and Iron(II) sulfide (FeS), which are rejected from

10988-622: The island, and the eventual permanent closing of the mine. As of 2005, only three mines operated by international companies continued to use river disposal: The Ok Tedi mine , the Grasberg mine and the Porgera mine , all on New Guinea. This method is used in these cases due to seismic activity and landslide dangers which make other disposal methods impractical and dangerous. Commonly referred to as STD (Submarine Tailings Disposal) or DSTD (Deep Sea Tailings Disposal). Tailings can be conveyed using

11122-535: The large exposed surface area of the minerals. The fraction of tailings to ore can range from 90 to 98% for some copper ores to 20–50% of the other (less valuable) minerals. The rejected minerals and rocks liberated through mining and processing have the potential to damage the environment by releasing toxic metals (arsenic and mercury being two major culprits), by acid drainage (usually by microbial action on sulfide ores), or by damaging aquatic wildlife that rely on clear water (vs suspensions). Tailings ponds can also be

11256-643: The leaching of iron, manganese, and aluminum residues into waterways and acid mine drainage . The runoff can create both surface and groundwater contamination. The piles also create a fire hazard, with the potential to spontaneously ignite. Because most coal refuse harbors toxic components, it is not easily reclaimed by replanting with plants like beach grasses. Early mining operations often did not take adequate steps to make tailings areas environmentally safe after closure. Modern mines, particularly those in jurisdictions with well-developed mining regulations and those operated by responsible mining companies, often include

11390-434: The material's high alkalinity , if not stored properly, it can pose a significant environmental hazard. As a result, significant effort is being invested in finding better methods for safe storage and dealing with it such as waste valorization in order to create useful materials for cement and concrete . Coal refuse (also described as coal waste, rock, slag, coal tailings, waste material, rock bank, culm, boney, or gob)

11524-418: The measured total alkalinity is set equal to: (Subscript T indicates the total concentration of the species in the solution as measured. This is opposed to the free concentration, which takes into account the significant amount of ion pair interactions that occur in seawater.) Alkalinity can be measured by titrating a sample with a strong acid until all the buffering capacity of the aforementioned ions above

11658-535: The metals due to the difficulties of transporting them, but the copper was eventually traded throughout the continent along major river routes. In the early colonial history of the Americas, "native gold and silver was quickly expropriated and sent back to Spain in fleets of gold- and silver-laden galleons", the gold and silver originating mostly from mines in Central and South America. Turquoise dated at 700 AD

11792-768: The mid-19th century, mining for minerals and precious metals, along with ranching , became a driving factor in the U.S. Westward Expansion to the Pacific coast. With the exploration of the West, mining camps sprang up and "expressed a distinctive spirit, an enduring legacy to the new nation"; Gold Rushers would experience the same problems as the Land Rushers of the transient West that preceded them. Aided by railroads, many people traveled West for work opportunities in mining. Western cities such as Denver and Sacramento originated as mining towns. When new areas were explored, it

11926-497: The mid-sixteenth century. On the continent, mineral deposits belonged to the crown, and this regalian right was stoutly maintained. But in England, royal mining rights were restricted to gold and silver (of which England had virtually no deposits) by a judicial decision of 1568 and a law in 1688. England had iron , zinc , copper , lead , and tin ores. Landlords who owned the base metals and coal under their estates then had

12060-432: The minehead, where the water was stored in large reservoirs and tanks. When a full tank was opened, the flood of water sluiced away the overburden to expose the bedrock underneath and any gold-bearing veins. The rock was then worked by fire-setting to heat the rock, which would be quenched with a stream of water. The resulting thermal shock cracked the rock, enabling it to be removed by further streams of water from

12194-400: The mineral-rich material and extract the desired compounds and metals from the ore. Alkalinity Alkalinity (from Arabic : القلوية , romanized :  al-qaly , lit.   'ashes of the saltwort ') is the capacity of water to resist acidification . It should not be confused with basicity , which is an absolute measurement on the pH scale. Alkalinity is

12328-431: The mining of previously impenetrable metals and ores. In 1762, one of the world's first mining academies was established in the same town there. The widespread adoption of agricultural innovations such as the iron plowshare , as well as the growing use of metal as a building material, was also a driving force in the tremendous growth of the iron industry during this period. Inventions like the arrastra were often used by

12462-423: The molar amount of bases in a solution that can be converted to uncharged species by a strong acid. For example, 1 mole of HCO 3 in solution represents 1 molar equivalent, while 1 mole of CO 3 is 2 molar equivalents because twice as many H ions would be necessary to balance the charge. The total charge of a solution always equals zero. This leads to a parallel definition of alkalinity that

12596-439: The naphtha, which was considered as waste during the procedure of refining oil. Both of those degraded products are useful. Aliphatic, aromatic hydrocarbons and methane can be used as fuel in the humans' daily lives. In other words, these methanogens improve the coefficient of utilization. Moreover, these methanogens change the structure of the tailings pond and help the pore water efflux to be reused for processing oil sands. Because

12730-550: The nonconservative ions which accept or donate protons and thus define alkalinity are clustered on the other side of the equation. This combined charge balance and proton balance is called total alkalinity . Total alkalinity is not (much) affected by temperature, pressure, or pH, and is thus itself a conservative measurement, which increases its usefulness in aquatic systems. All anions except HCO 3 and CO 3 have low concentrations in Earth's surface water (streams, rivers, and lakes). Thus carbonate alkalinity , which

12864-405: The ore body. This leads to a mathematical resource estimation to estimate the size and grade of the deposit. This estimation is used to conduct a pre-feasibility study to determine the theoretical economics of the ore deposit. This identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. The next step

12998-462: The ore concentrates, engineering concerns, milling and infrastructure costs, finance and equity requirements, and an analysis of the proposed mine from the initial excavation all the way through to reclamation. The proportion of a deposit that is economically recoverable is dependent on the enrichment factor of the ore in the area. To gain access to the mineral deposit within an area it is often necessary to mine through or remove waste material which

13132-442: The ore, lower wages, decreased occupational safety, benefits, and health standards for miners, and a lack of environmental protection measures. Artisanal miners often undertake the activity of mining seasonally. For example, crops are planted in the rainy season , and mining is pursued in the dry season . However, they also frequently travel to mining areas and work year-round. There are four broad types of ASM: Surface mining

13266-570: The overhead tanks. The Roman miners used similar methods to work cassiterite deposits in Cornwall and lead ore in the Pennines . Sluicing methods were developed by the Romans in Spain in 25 AD to exploit large alluvial gold deposits, the largest site being at Las Medulas , where seven long aqueducts tapped local rivers and sluiced the deposits. The Romans also exploited the silver present in

13400-413: The pH of bicarbonate or carbonate is consumed. This point is functionally set to pH 4.5. At this point, all the bases of interest have been protonated to the zero level species, hence they no longer cause alkalinity. In the carbonate system the bicarbonate ions [ HCO 3 ] and the carbonate ions [ CO 3 ] have become converted to carbonic acid [H 2 CO 3 ] at this pH. This pH is also called

13534-493: The paste are also normally higher than for conventional tailings as positive displacement pumps are normally required to transport the tailings from the processing plant to the storage area. Paste tailings are used in several locations around the world including Sunrise Dam in Western Australia and Bulyanhulu Gold Mine in Tanzania. Tailings do not have to be stored in ponds or sent as slurries into oceans, rivers or streams. There

13668-512: The plant's roots can prevent water erosion, immobilise metals by adsorption or accumulation, and provide a zone around the roots where the metals can precipitate and stabilise. Pollutants become less bioavailable and livestock, wildlife, and human exposure is reduced. This approach can be especially useful in dry environments, which are subject to wind and water dispersion. Considerable effort and research continues to be made into discovering and refining better methods of tailings disposal. Research at

13802-449: The processing cycle. Once a storage facility is filled and completed, the surface can be covered with topsoil and revegetation commenced. However, unless a non-permeable capping method is used, water that infiltrates into the storage facility will have to be continually pumped out into the future. Paste tailings is a modification to the conventional methods of disposal of tailings (pond storage). Conventional tailings slurries are composed of

13936-540: The rehabilitation and proper closure of tailings areas in their costs and activities. For example, the Province of Quebec , Canada, requires not only the submission of a closure plan before the start of mining activity, but also the deposit of a financial guarantee equal to 100% of the estimated rehabilitation costs. Tailings dams are often the most significant environmental liability for a mining project. Mine tailings may have economic value in carbon sequestration due to

14070-431: The remaining part of a coal seam previously exploited by other surface-mining techniques has too much overburden to be removed but can still be profitably exploited from the side of the artificial cliff made by previous mining. A typical cycle alternates sumping, which undercuts the seam, and shearing, which raises and lowers the cutter-head boom to cut the entire height of the coal seam. As the coal recovery cycle continues,

14204-446: The shafts could no longer be pumped dry with the available technology. Although an increased use of banknotes , credit and copper coins during this period did decrease the value of, and dependence on, precious metals , gold and silver still remained vital to the story of medieval mining. Due to differences in the social structure of society, the increasing extraction of mineral deposits spread from central Europe to England in

14338-567: The silver mines of Laurium , which helped support the Greek city state of Athens . Although they had over 20,000 slaves working them, their technology was essentially identical to their Bronze Age predecessors. At other mines, such as on the island of Thassos , marble was quarried by the Parians after they arrived in the 7th century BC. The marble was shipped away and was later found by archaeologists to have been used in buildings including

14472-458: The size of a grain of sand to a few micrometres. Mine tailings are usually produced from the mill in slurry form, which is a mixture of fine mineral particles and water. Tailings are likely to be dangerous sources of toxic chemicals such as heavy metals , sulfides and radioactive content. These chemicals are especially dangerous when stored in water in ponds behind tailings dams . These ponds are also vulnerable to major breaches or leaks from

14606-438: The slurry produced from tar sands mining. Tailings are sometimes mixed with other materials such as bentonite to form a thicker slurry that slows the release of impacted water to the environment. There are many different subsets of this method, including valley impoundments, ring dikes, in-pit impoundments, and specially dug pits. The most common is the valley pond, which takes advantage of the natural topographical depression in

14740-413: The solution lowers its pH, but does not affect alkalinity. At all pH values: Only at high (basic) pH values: Addition of CO 2 to a solution in contact with a solid can (over time) affect the alkalinity, especially for carbonate minerals in contact with groundwater or seawater. The dissolution (or precipitation) of carbonate rock has a strong influence on the alkalinity. This is because carbonate rock

14874-488: The sought-after ores of copper and nickel, as well as coal. Although harmless underground, these minerals are reactive toward air in the presence of microorganisms, which if not properly managed lead to acid mine drainage . Between 100 million and 280 million tons of phosphogypsum waste are estimated to be produced annually as a consequence of the processing of phosphate rock for the production of phosphate fertilizers. In addition to being useless and abundant, phosphogypsum

15008-518: The strength of a buffer solution composed of weak acids and their conjugate bases . It is measured by titrating the solution with an acid such as HCl until its pH changes abruptly, or it reaches a known endpoint where that happens. Alkalinity is expressed in units of concentration, such as meq/L ( milliequivalents per liter ), μeq/kg (microequivalents per kilogram), or mg/L CaCO 3 (milligrams per liter of calcium carbonate ). Each of these measurements corresponds to an amount of acid added as

15142-474: The surface through the tunnels and shafts. Sub-surface mining can be classified by the type of access shafts used, and the extraction method or the technique used to reach the mineral deposit. Drift mining uses horizontal access tunnels, slope mining uses diagonally sloping access shafts, and shaft mining uses vertical access shafts. Mining in hard and soft rock formations requires different techniques. Other methods include shrinkage stope mining , which

15276-439: The surface. This method is used by the gold mine on Lihir Island ; its waste disposal has been viewed by environmentalists as highly damaging, while the owners claim that it is not harmful. Phytostabilisation is a form of phytoremediation that uses hyperaccumulator plants for long-term stabilisation and containment of tailings, by sequestering pollutants in soil near the roots. The plant's presence can reduce wind erosion, or

15410-511: The surrounding environment. The removal of water not only can create a better storage system in some cases (e.g. dry stacking, see below) but can also assist in water recovery which is a major issue as many mines are in arid regions. In a 1994 description of tailings impoundments, however, the U.S. EPA stated that dewatering methods may be prohibitively expensive except in special circumstances. Subaqueous storage of tailings has also been used. Tailing ponds are areas of refused mining tailings where

15544-602: The tomb of Amphipolis. Philip II of Macedon , the father of Alexander the Great , captured the gold mines of Mount Pangeo in 357 BC to fund his military campaigns. He also captured gold mines in Thrace for minting coinage, eventually producing 26 tons per year. However, it was the Romans who developed large-scale mining methods, especially the use of large volumes of water brought to the minehead by numerous aqueducts . The water

15678-448: The top of a mountain off to reach ore deposits at depth. Most placer deposits, because they are shallowly buried, are mined by surface methods. Finally, landfill mining involves sites where landfills are excavated and processed. Landfill mining has been thought of as a long-term solution to methane emissions and local pollution. High wall mining, which evolved from auger mining, is another form of surface mining. In high wall mining,

15812-628: The top slats. Many examples of such devices have been found in old Roman mines and some examples are now preserved in the British Museum and the National Museum of Wales . Mining as an industry underwent dramatic changes in medieval Europe . The mining industry in the early Middle Ages was mainly focused on the extraction of copper and iron . Other precious metals were also used, mainly for gilding or coinage. Initially, many metals were obtained through open-pit mining , and ore

15946-415: The total alkalinity due to the common occurrence and dissolution of carbonate rocks and other geological weathering processes that produce carbonate anions. Other common natural components that can contribute to alkalinity include borate , hydroxide , phosphate , silicate , dissolved ammonia , and the conjugate bases of organic acids (e.g., acetate ). Solutions produced in a laboratory may contain

16080-415: The toxic chemicals could be potentially hazardous to human health; however, it is also harmful to the environment. Tailing ponds are often somewhat dangerous because they attract wildlife such as waterfowl or caribou as they appear to be a natural pond, but they can be highly toxic and harmful to the health of these animals. Tailings ponds are used to store the waste made from separating minerals from rocks, or

16214-433: The valuable minerals, or hard rock mining , which pulverizes the rock containing the ore and then relies on chemical reactions to concentrate the sought-after material. In the latter, the extraction of minerals from ore requires comminution , i.e., grinding the ore into fine particles to facilitate extraction of the target element(s). Because of this comminution, tailings consist of a slurry of fine particles, ranging from

16348-447: The waterborne refuse material is pumped into a pond to allow the sedimentation (meaning separation) of solids from the water. The pond is generally impounded with a dam, and known as tailings impoundments or tailings dams. It was estimated in 2000 that there were about 3,500 active tailings impoundments in the world. The ponded water is of some benefit as it minimizes fine tailings from being transported by wind into populated areas where

16482-469: The world's gold, followed by the establishment of large mines such as the Mount Morgan Mine , which ran for nearly a hundred years, Broken Hill ore deposit (one of the largest zinc-lead ore deposits), and the iron ore mines at Iron Knob . After declines in production, another boom in mining occurred in the 1960s. In the early 21st century, Australia remains a major world mineral producer. As

16616-474: The world, which was increasingly demanding copper for electrical and household goods. Canada's mining industry grew more slowly than did the United States due to limitations in transportation, capital, and U.S. competition; Ontario was the major producer of the early 20th century with nickel, copper, and gold. Meanwhile, Australia experienced the Australian gold rushes and by the 1850s was producing 40% of

16750-628: Was mined in pre-Columbian America; in the Cerillos Mining District in New Mexico , an estimate of "about 15,000 tons of rock had been removed from Mt. Chalchihuitl using stone tools before 1700." In 1727 Louis Denys (Denis) (1675–1741), sieur de La Ronde – brother of Simon-Pierre Denys de Bonaventure and the son-in-law of René Chartier – took command of Fort La Pointe at Chequamegon Bay ; where natives informed him of an island of copper. La Ronde obtained permission from

16884-576: Was primarily extracted from shallow depths, rather than through deep mine shafts. Around the 14th century , the growing use of weapons , armour , stirrups , and horseshoes greatly increased the demand for iron. Medieval knights , for example, were often laden with up to 100 pounds (45 kg) of plate or chain link armour in addition to swords , lances and other weapons. The overwhelming dependency on iron for military purposes spurred iron production and extraction processes. The silver crisis of 1465 occurred when all mines had reached depths at which

17018-541: Was slightly greater in the deep ocean, and named this increase alkalinity. Also in 1884, Svante Arrhenius submitted his PhD theses in which he advocated the existence of ions in solution, and defined acids as hydronium ion donors and bases as hydroxide ion donors. For that work, he received the Nobel Prize in Chemistry in 1903. See also Svante Arrhenius#Ionic disassociation . Alkalinity roughly refers to

17152-406: Was still present near the surface in colonial times. Indigenous peoples used Lake Superior copper from at least 5,000 years ago; copper tools, arrowheads, and other artifacts that were part of an extensive native trade-network have been discovered. In addition, obsidian , flint , and other minerals were mined, worked, and traded. Early French explorers who encountered the sites made no use of

17286-591: Was the country's biggest environmental disaster. The dam breach caused the death of 19 people due to flooding of tailings slime downstream and affected some 400 km of the Doce river system with toxic effluence and out into the Atlantic Ocean. Tailings deposits tend to be located in rural areas or near marginalized communities, such as indigenous communities . The Global Industry Standard on Tailings Management recommends that "a human rights due diligence process

17420-411: Was the removal of water from mining shafts. As miners dug deeper to access new veins, flooding became a very real obstacle. The mining industry became dramatically more efficient and prosperous with the invention of mechanically- and animal-driven pumps. Iron metallurgy in Africa dates back over four thousand years. Gold became an important commodity for Africa during the trans-Saharan gold trade from

17554-524: Was to contain the tailings slurry with locally available earthen materials. This slurry is a dilute stream of the tailings solids within water that was sent to the tailings storage area. The modern tailings designer has a range of tailings products to choose from depending upon how much water is removed from the slurry prior to discharge. It is increasingly common for tailings storage facilities to require special barriers like Bituminous Geomembranes (BGMs) to contain liquid tailings slurries and prevent impact to

17688-403: Was used for a variety of purposes, including removing overburden and rock debris, called hydraulic mining , as well as washing comminuted , or crushed, ores and driving simple machinery. The Romans used hydraulic mining methods on a large scale to prospect for the veins of ore, especially using a now-obsolete form of mining known as hushing . They built numerous aqueducts to supply water to

17822-465: Was used. At other parts of the site, they penetrated the water table and dewatered the mines using several kinds of machines, especially reverse overshot water-wheels . These were used extensively in the copper mines at Rio Tinto in Spain, where one sequence comprised 16 such wheels arranged in pairs, and lifting water about 24 metres (79 ft). They were worked as treadmills with miners standing on

17956-539: Was usually the gold ( placer and then lode ) and then silver that were taken into possession and extracted first. Other metals would often wait for railroads or canals, as coarse gold dust and nuggets do not require smelting and are easy to identify and transport. In the early 20th century, the gold and silver rush to the western United States also stimulated mining for coal as well as base metals such as copper, lead, and iron. Areas in modern Montana, Utah, Arizona, and later Alaska became predominant suppliers of copper to

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