Manganese, Phosphate and Coal Mining

Manganese, Phosphate and Coal Mining A Comparative Study

Introduction This comparative study was undertaken in order to help Mr. Businessman, who have decided to increase his earnings through mining, choose wisely among three project proposals. All three mining industries entail a huge amount of financial investment, thus, requiring the expert advice of a mineral expert/geologist, an economist and an industrialist. With this extensive comparative study, it is expected that Mr. Businessman will eventually be able to make the right decision and put his money into good use.

Manganese

Manganese is a chemical element, designated by the symbol Mn with an atomic number of 25. It is found as a free element in nature (often in combination with iron), and in many minerals. It is a hard, yet brittle, grey white metal which resembles iron.

It has paramagnetic properties, which means that it demonstrates strong magnetic characteristics in the presence of an external magnetic field. It, however, is not magnetic by itself. Manganese is used as a key component in the iron and steel manufacturing industries. The processing of iron is the largest consuming sector of manganese and it contributes to about 85% of its production. Manganese is also used as a key element of stainless steel alloys and some aluminum alloys.

Manganese is a reactive element that easily combines with ions in water and air. In the Earth, manganese is found in a number of minerals of different chemical and physical properties, but is never found as a free metal in nature. The most important mineral is pyrolusite, because it is the main ore mineral for manganese. Trace amounts of manganese are very important for a better health coondition. It makes bones strong yet flexible, and it aids the body in absorbing Vitamin B1. It is also an important activator for the body to use enzymes. As little as 0.00002% Mn in the human body is essential. Studies have shown that lack of manganese leads to infertility in animals.

Sources of Manganese Over 80% of the known world manganese resources are found in South Africa and Ukraine. Other important manganese deposits are in China, Australia, Brazil, Gabon, India, and Mexico. The United States imports manganese ore because the manganese resources in the U.S. are relatively low in manganese content per ton of ore. Importing these ores is presently more economic than mining them locally. Most manganese ore imported to the United States is used to manufacture intermediate manganese ferroalloy products and electrolytic manganese for use in dry-cell batteries. Only a small amount of the ore is directly used in the steel making process.

Sources of Manganese Deep-sea nodules of manganese and other metals are scattered on the ocean floor. They form when the hot waters from hot springs (called black smokers) on the ocean bottom meet the cold, deep ocean water. The elements in the hot volcanic waters precipitate as nodules. Though rich in manganese (nearly 25% manganese) they are very deep in the ocean and it would cost too much to make them worth retrieving. This may prove to be an important source of manganese in the future should reserves in the Earth's crust be depleted and cost-effective deep-sea mining methods are discovered.

Uses of Manganese

Manganese Mining

The first step in a conventional production flow sheet for converting manganese oxide ore to alkaline grade electrolytic manganese dioxide (EMD), which is a high purity product that possesses the ‘recipe specific’ electrical characteristics desired by batterymakers, is a high temperature pyrometallurgical roast process, wherein the manganese ore is heated to between 800°C and 900°C to reduce it so that it can then be dissolved in hot sulfuric acid.

Drawbacks of the pyrometallurgical roast processthat will inhibit its future use include: • As the roasting process reduces all oxides present in the ore, Electrolytic Manganese Dioxide (EMD) producers must compete with steel and chemical industry buyers for the highest grades of manganese oxide fines if they are to ameliorate the production and product quality problems caused by non-manganese metal ions in the sulfate electrolyte; • In today’s world, the steel industry alone can consume all of the high grade manganese oxide ores that are available leaving existing EMD plants, which are dependent on sourcing high grade ores, at risk of closure even in times when the market for their EMD production is particularly strong;

Drawbacks of the pyrometallurgical roast process that will inhibit its future use include: • The roasting process is highly energy inefficient with a conventional EMD plant requiring more than double the energy of a same-sized plant employing the Mesa modified sulfur dioxide leach technology; and • The roasting process is highly polluting, emitting high carbon dioxide loads to the atmosphere, particulate pollutants that can pollute the surrounding environment and very insidious metal ion pollutants that can find its way into streams and aquifers, travelling large distances before appearing in drinking water or crops grown for human consumption.

MESA MODIFIED SULFUR DIOXIDE LEACH TECHNOLOGY

The principal sub-processes depicted in the diagram above are as follows:

Phosphate

In 2007, at that time’s current rate of consumption, the supply of phosphorus was estimated to run out in 345 years. However, scientists are now claiming that a "Peak Phosphorus" will occur in 30 years and that "At current rates, reserves will be depleted in the next 50 to 100 years."

In ecological terms, because of its important role in biological systems, phosphate is a highly sought after resource. Once used, it is often a limiting nutrient in environments, and its availability may govern the rate of growth of organisms. • This is generally true of freshwater environments, whereas nitrogen is more often the limiting nutrient in marine (seawater) environments. Addition of high levels of phosphate to environments and to micro-environments in which it is typically rare can have significant ecological consequences. • For example, blooms in the populations of some organisms at the expense of others, and the collapse of populations deprived of resources such as oxygen (see eutrophication) can occur. • In the context of pollution, phosphates are one component of total dissolved solids, a major indicator of water quality.

Phosphate deposits can contain significant amounts of naturally occurring heavy metals. • Mining operations processing phosphate rock can leave tailing piles containing elevated levels of cadmium, lead, nickel, copper, chromium, and uranium. • Unless carefully managed, these waste products can leach heavy metals in the groundwater or nearby estuaries. • Uptake of these substances by plants and marine life can lead to concentrated levels of toxic heavy metals in food products.

Phosphate Mining

Coal

Coal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. • The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. • Coal is composed primarily of carbon along with variable quantities of other elements, chiefly sulfur, hydrogen, oxygen and nitrogen.

Coal Mining

The most economical method of coal extraction from coal seams depends on the depth and quality of the seams, and the geological and environmental factors. • Coal mining processes are differentiated by whether they operate on the surface or underground. • Many coals extracted from both surface and underground mines require washing in a coal preparation plant.

Technical and economic feasibility are evaluated based on: • regional geologic conditions; • overburden characteristics; • coal seam continuity, thickness, structure, quality, and depth; • strength of materials above and below the seam for roof and floor conditions; • topography (especially altitude and slope); • climate; • land ownership as it affects the availability of land for mining and access; • surface drainage patterns; • ground water conditions; • availability of labor and materials; • coal purchaser requirements in terms of tonnage, quality, and destination; • and capital investment requirements.

The choice of mining method depends primarily on the: • depth of burial • density of the overburden • thickness of the coal seam • Two basic methods of coal mining: • Surface mining • Deep underground mining Seams relatively close to the surface, at depths less than approximately 180 ft (50 m), are usually surface mined. Coal that occurs at depths of 180 to 300 ft (50 to 100 m) are usually deep mined but, in some cases, surface mining techniques can be used. For example, some western U.S. coal that occur at depths in excess of 200 ft (60 m) are mined by open pit methods, due to thickness of the seam 60–90 feet (20–30 m). Coals occurring below 300 ft (100 m) are usually deep mined.

Modern Surface Mining

Area Mining • Strip mining exposes the coal by removing the overburden (the earth above the coal seam(s)) in long cuts or strips. • The spoil from the first strip is deposited in an area outside the planned mining area. • Spoil from subsequent cuts is deposited as fill in the previous cut after coal has been removed. Usually, the process is to drill the strip of overburden next to the previously mined strip. • The drill holes are filled with explosives and blasted. • The overburden is then removed using large earthmoving equipment such as draglines, shovel and trucks, excavator and trucks, or bucket-wheels and conveyors. • This overburden is put into the previously mined (and now empty) strip. • When all the overburden is removed, the underlying coal seam will be exposed (a 'block' of coal). • This block of coal may be drilled and blasted (if hard) or otherwise loaded onto trucks or conveyors for transport to the coal preparation (or wash) plant. • Once this strip is empty of coal, the process is repeated with a new strip being created next to it. • This method is most suitable for areas with flat terrain.

Contour Mining • The contour mining method consists of removing overburden from the seam in a pattern following the contours along a ridge or around a hillside. • This method is most commonly used in areas with rolling to steep terrain. • It was once common to deposit the spoil on the downslope side of the bench thus created, but this method of spoil disposal consumed much additional land and created severe landslide and erosion problems. • To alleviate these problems, a variety of methods were devised to use freshly cut overburden to refill mined-out areas. • These haul-back or lateral movement methods generally consist of an initial cut with the spoil deposited downslope or at some other site and spoil from the second cut refilling the first. • A ridge of undisturbed natural material 15 to 20 ft (5–6 m}} wide is often intentionally left at the outer edge of the mined area. • This barrier adds stability to the reclaimed slope by preventing spoil from slumping or sliding downhill.

Contour Mining limitations • The limitations on contour strip mining are both economic and technical. • When the operation reaches a predetermined stripping ratio (tons of overburden/tons of coal), it is not profitable to continue. • Depending on the equipment available, it may not be technically feasible to exceed a certain height of high wall. • At this point, it is possible to produce more coal with the augering method in which spiral drills bore tunnels into a high wall laterally from the bench to extract coal without removing the overburden.

Mountaintop removal Mining • Mountaintop coal mining is a surface mining practice involving removal of mountaintops to expose coal seams, and disposing of associated mining overburden in adjacent "valley fills." • Valley fills occur in steep terrain where there are limited disposal alternatives. • Mountaintop removal methodcombines area and contour strip mining methods. In areas with rolling or steep terrain with a coal seam occurring near the top of a ridge or hill, the entire top is removed in a series of parallel cuts. • Overburden is deposited in nearby valleys and hollows. This method usually leaves ridge and hill tops as flattened plateaus.

Mountaintop removal Mining • The process is highly controversial for the drastic changes in topography, the practice of creating head-of-hollow-fills, or filling in valleys with mining debris, and for covering streams and disrupting ecosystems. • Spoil is placed at the head of a narrow, steep-sided valley or hollow. • In preparation for filling this area, vegetation and soil are removed and a rock drain constructed down the middle of the area to be filled, where a natural drainage course previously existed. • When the fill is completed, this underdrain will form a continuous water runoff system from the upper end of the valley to the lower end of the fill. • Typical head-of-hollow fills are graded and terraced to create permanently stable slopes.

Room and pillar mining • Room and pillar mining consists of coal deposits that are mined by cutting a network of rooms into the coal seam. • Pillars of coal are left behind in order to keep up the roof. • The pillars can make up to forty percent of the total coal in the seam. • However, this can be extracted at a later stage.

Underground mining • Most coal seams are too deep underground for opencast mining and require underground mining, which method currently accounts for about 60% of world coal production. • In deep mining, the room and pillar or board and pillar method progresses along the seam, while pillars and timber are left standing to support the mine roof. • Once room and pillar mines have been developed to a stopping point (limited by geology, ventilation, or economics), a supplementary version of room and pillar mining, termed second mining or retreat mining, is commonly started. • Miners remove the coal in the pillars, thereby recovering as much coal from the coal seam as possible. A work area involved in pillar extraction is called a pillar section. • Modern pillar sections use remote-controlled equipment, including large hydraulic mobile roof-supports, which can prevent cave-ins until the miners and their equipment have left a work area. • The mobile roof supports are similar to a large dining-room table, but with hydraulic jacks for legs. • After the large pillars of coal have been mined away, the mobile roof support's legs shorten and it is withdrawn to a safe area. • The mine roof typically collapses once the mobile roof supports leave an area.

Five principal methods of Underground mining

Comparative Graphical Diagram of the Market Value of the Three Mining Minerals for the Past Years

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Manganese, Phosphate and Coal Mining

Manganese, Phosphate and Coal Mining

Presentation Transcript

Coal Mining

Bituminous Coal Mining

Coal Mining

Coal Mining

Mining - Coal

Coal Mining

Coal Mining

Coal mining

Coal Mining.

Coal Mining

Coal Mining Debate!

Coal Mining

Australian Coal Mining

Anthracite Coal Mining

Manganese, Phosphate and Coal Mining

Coal Mining

Investing In Coal and Coal Mining Process

Metalliferous and Coal Mining Solutions

Historic Coal Mining

Coal Mining Activities

Coal Mining