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By Mustafa Akser

Dwindling economic deposits of rutile (TiO2) prompted research on recovering it from secondary sources. One such resource is in Southwestern Turkey feldspar mining rejects that contain 5%-6% TiO2 mostly rutile. Previous studies could only upgrade the TiO2 to 36% TiO2 grade, claiming that the leftover flotation reagents on the surfaces of rutile and host minerals detrimentally affected upgrading of the rutile. As a potential remedy to this concern, a laboratory sample (from an operating feldspar mine in Milas, Turkey) was first caustic scrubbed, then air calcined at 400°C to evaporate the oily reagents. Subsequent physical separation of rutile included wet screening, gravity, magnetic, and electrostatic separation technologies. Such processes indeed improved the grade of the rutile concentrate up to 83 % TiO2 Low recovery of the TiO2 (<20%), was attributed to lack of full liberation of rutile, even at 125x44 micron range; interference with impurity minerals such as sphene and zircon; and simply the process inefficiency in upgrading the fine grains through conventional separation technologies for heavy minerals.

Jan 1, 1999

By K. G. Colman

Introduction This text is intended to provide the operator and turnkey contractor with the basic data for sizing vibrating screens to be used in ore crushing plants. The basic capacities, modifying factors, etc.. used in the area requirement calculations were developed empirically and modified to their present values based upon years of practical applications. It must be pointed out that screening is much more of an art than an exact science; however. the information presented here should provide for reasonably accurate screen sizing when applied to many metallic ores. Types of Screens There are two types of screens which can be used for strictly sizing applications. These are two- and four-bearing screens; both are inclined circle-throw machines. Two-Bearing Screens The motion of a two-bearing screen is generated by unbalanced weights attached to the vibrator shaft. The body of the machine is usually supported by steel coil springs (see Fig. 8). The main advantage

Jan 1, 1985

By John F. Clarkson

White Pine Copper Company built and operated, from August, 1962 through May, 1963, a pilot plant to recover copper using a cyanide percolation leach of the sand fraction (+400 mesh) of the mill tailings (1, 2, 3). The pilot plant runs were metallurgically successful and preliminary engineering studies for a full scale operation were completed under contract by an outside engineering firm. Unfortunately, the net return projected at that time did not justify the proposed capital&apos; investment. In the summer of 1973 the project was revived. The rise in selling price of copper over the previous ten years, compared to the projected operating cost of the leach plant, increased the calculated net return on investment with the most recent figures showing a 30% DCF. Basically, the reason for this favorable shift in profitability was that the cost for many of the reagents did not go up as fast in the previous ten years as did the selling price of copper. Using the Chemical Marketing Reporter costs, NaCN sold for 18.3¢/lb in 1963 and 20.75¢/lb in August, 1973. During this same period H2S04 went from $23.50 per ton to $35.90 per ton. In comparison, producer&apos;s prices for electrolytic copper were 31¢/lb in 1963 and 619 in 1973. Thus the price of copper went up 97% while the two reagents only increased 13% and 53%, respectively. The capital investment also escalated but, again, not to the same extent as the selling price of copper. These price differences no longer are valid&apos; but they did provide justification for reexamining the project.

Jan 1, 1975

By R. Sivamohan, F. Huang

A mineral processing strategy developed for the finely and complexly interlayered calcite rich wollastonite, microcline, and iron-garnet ore of Jokkmokk, northern Sweden, gives an overall calcite recovery of 89.4% at a grade of 90.7% CaCO3. The wollastonite product assays 53.0% Ca- SiO3 at a recovery of 92.2%. The significant elements of the developed strategy are stepwise grinding, wet high intensity magnetic separation (WHIMS), reverse flotation and starvation flotation. Stepwise grinding avoids the overgrinding of soft calcite. WHIMS removes the colored iron-garnet impurity and thereby increases the whiteness of the product. Reverse flotation enables a simple flotation circuit and starvation `flotation helps to optimize the physicochemical conditions in cleaner flotation by giving rougher products of narrow particle size distributions. Moreover, with the reagent scheme developed in this work only one cleaner stage is necessary for the various rougher flotation products to be upgraded to give the foregoing results. In this paper, the strategy is presented in detail along with appropriate results.

Jan 1, 1990

By R. L. Grayson

A goal programming-based worker scheduling model has been incorporated in the Mine Management Support System (MMSS) for assigning workers to prioritized jobs on a shift basis. In the model the accomplishment of each regular and non-regular job is a goal. The objective is minimization of the deviations away from the goals. A number of coefficients are used as premultipliers of the decision variables in order to address practical considerations associated with the utilization of workers and the requirements of jobs. Some of these premultipliers will be updated expertly within MMSS, timely updating the statuses of the dynamic parameters.

Jan 1, 1991

By Edie Trimmer

Utah statute defines sovereign lands as "those lands lying below the ordinary high water mark of navigable bodies of water at the date of statehood, and owned by the state by virtue of its sovereignty." The lands within the bed of Great Salt Lake (GSL) are, by this definition, sovereign lands, acquired at statehood in 1896 in accordance with the "equal footing" doctrine, granting each state control and ownership of navigable waters and the lands underneath those waters within its borders. Under public trust doctrine, the state, as trustee for the people, bears responsibility for preserving and protecting the right of the public to use of the waters for navigation, commerce, fishing, recreation, and wildlife habitat. Also by statute, sovereign lands are defined as "state lands," to be managed by "multiple use sustained-yield principles." The Division of Forestry, Fire and State Lands is given management authority for sovereign lands and, as manager, has responsibility to prepare comprehensive plans, initiate studies of the lake and its resources, implement comprehensive plans through state and local entities, and coordinate the activities of various divisions within the Department of Natural Resources (DNR). The Division of Forestry, Fire and State Lands also has responsibility for management of mineral leasing on sovereign lands. The many resources on the lake--water, minerals, wildlife, recreation, archeological and historical values--are managed by as many state agencies which occasionally creates conflicts. The brines of GSL contain several ions that crystalize into valuable minerals during evaporation. The major ions in the lake are, in order of relative abundance, chloride, sodium, sulfate, magnesium, and potassium. Mineral products which are currently extracted from lake brines are sodium chloride, magnesium chloride brine which can be sold as flake magnesium chloride or further processed into magnesium and chlorine gas, and potassium sulfate. Mineral products which have potential for extraction include gypsum, sodium sulfate, and trace amounts of lithium, boron, and bromine. The GSL contained an estimated 4.3 billion short tons (st) (3.9 billion metric tons [mt]) of dissolved salts in 1998. Utah Geological Survey (UGS) estimates of the dissolved salt content in GSL have fluctuated from 4.0 to 5.5 billion st (3.6 to 5.0 billion mt) due to the dynamic conditions in the lake as salts are precipitated and redissolved, and due to the diversion of brines from GSL, such as the West Desert Pumping Project. The lake has four areas of varying salinity, separated by dikes or other man-made structures: north arm and Stansbury Bay brines at near saturation (25 to 27 percent total dissolved solids [TDS]); the main body of the south arm with concentrations ranging from 7 to 15 percent TDS as lake elevations fluctuate; the waters in Farmington Bay at approximately 3 to 5 percent TDS; and Bear River Bay at <1 to 7 percent TDS. The percent TDS in Bear River Bay fluctuates with lake level, and changes in Bear River inflow. The transfer of salts from the south arm to the north arm has raised questions about the viability of the mineral and brine shrimp industries. The UGS and the U.S. Geological Survey (USGS) continue to monitor salinities at designated sites on the lake to document changing lake salinity. A recurrent theme is that placement of dikes and diversions can have significant and rapid impacts on various conditions in the lake. Hydrocarbon resources on the lake are significant, but presently undeveloped. The hydrocarbons are low gravity (4 to 9 degree API) and tar-like, contain high nitrogen concentrations, and up to 12 percent sulfur. The unusual characteristics of the oil have been the subject of studies by chemists at Weber State University and University Louis Pasteur de Strasbourg. However, these resources are difficult, and at present, uneconomic to extract using current technology because of the nature of the hydrocarbons, and production in "an offshore, highly saline environment." Oolitic sand deposits make up many of the beaches and shorelines around the lake. Because of their high calcium carbonate content, oolites have been used by Magnesium Corporation of America (MagCorp) and its predecessors for acid neutralization and dike construction. Oolites are also used in very minor amounts in flower drying. The Utah Division of Oil, Gas and Mining reports up to 130,000 st (118,000 mt) mined annually by MagCorp from U.S. Bureau of Land Management (BLM) lands adjacent to GSL. Currently, there are twelve producing mineral leases which generated slightly more than $1,000,000 in royalties during calendar year 1998. IMC Kalium Ogden Corp. (IMC Kalium) produces potassium sulfate and magnesium chloride from brines concentrated through solar evaporation in Bear River Bay and Clyman Bay. By-product sodium chloride is transferred to IMC Salt, which packages and sells the salt. MagCorp produces magnesium metal from brines concentrated in Stansbury Bay. Cargill Salt produces sodium chloride from brines provided by MagCorp under a lease agreement. Morton Salt produces salt at the southeast end of Stansbury Island. Lastly, North Shore Limited produces cocentrated brines for use in dietary and mineral/vitamin supplements near Spring Bay in the north arm of the lake. Producers of magnesium, potash, and salt from GSL contribute significantly to the value of metals and industrial minerals in Utah. Together these companies contribute approximately $240 million in gross value, or 18 percent of the value of the state&apos;s nonfuel mineral production. Most of this production is exported.

Jan 1, 2001

By D. W. Alberter

I consider it a great pleasure and distinction to be invited to appear before your organization to discuss our experiences with a comparatively new system of what is known as a "Full Dimension" extensible conveyor system. One of these systems has been operating in our Diamond Smokeless Mine, Boltz, Pennsylvania, since 1959 servicing a continuous mining machines For those of you who are not familiar with this method of transportation, I would like to offer an explanation.

Jan 1, 1962

By Bruce B. Hanshaw

The Tertiary carbonate aquifer of central Florida is composed of about 2/3 calcite and 1/3 dolomite with minor amounts of quartz and apatite. The Mg content of the calcite is lower in the recharge areas than in the deeper confined parts of the aquifer system. Various geochemical lines of evidence indicate that much of the dolomite is of penecontemporaneous origin but that some may have been formed much later, possibly by ground water. Theoretical studies indicate that the Mg/Ca ratio in solutions is about unity for the three-phase equilibrium, calcite-dolomite-water. Solutions, such as ocean water and some subsurface brines, have Mg/Ca ratios higher than one and should represent dolomitizing solutions. In the areas of principal recharge to the Floridan aquifer, ground water is undersaturated with respect to both calcite and dolomite, and the Mg/Ca ratiois as low as 0.05. As the water moves downgradient, the Mg/Ca ratio systematically increases and approaches unity; saturation of the solution with respect to both calcite and dolomite also increases with length of travel in the system. Thus, in the zone of active potable-water circulation, the chemical process is one of dissolution of minerals until saturation is reached or exceeded. However, in the deeper brackish-water zones that underlie peninsular Florida, dolomite may be forming where the Mg/Ca ratio is greater than one. The necessary Mg may be derived from ocean water or brines recycled through the system as the hydrologic regimen is changed. The driving force may be simple mixing, relative fluctuations of sea level, or a combination of mechanisms.

Jan 1, 1972

By J. F. Brune, A. Verma

"Face ignitions in underground coal mines are a major risk for underground mining operations, as they can lead to methane or coal dust explosions. The 2010 disaster at the Upper Big Branch Mine resulted in 29 fatalities due to a methane and coal dust explosion initiated from a face ignition. Much research has been conducted to mitigate face ignition hazards, from water sprays to installing passive and active explosion barriers. Despite the increased use of water sprays in U.S. coal mines, there have been more than 50 documented face ignitions in the U.S. underground coal mines since 2010, indicating that this hazard still prevails. This paper will examine the statistics of face ignitions and gas explosion in U.S. coal mines based on MSHA data. It will study factors contributing to these face ignitions and outline best practices for their prevention based on experience and practices worldwide. INTRODUCTION Methane and coal dust explosions are one of the major causes of coal mine disasters in the U.S. and around the world. Such disasters have resulted in the large number of fatalities and loss of mine infrastructure. The recent explosion at the Soma coal mine in Turkey has caused the death of 301 miners (Mining Turkey, 2014). As documented by U.S. Mine Safety and Health Administration (MSHA, 2015a), the U.S. coal mining industry has also experienced several catastrophic mine explosions with accidents at Upper Big Branch mine, Darby mine, Sago mine and Jim Walter Resources No. 5 mine in the last decade, causing the deaths of almost 60 miners. Every explosion requires a source of ignition, the right amount of fuel and oxygen. In underground coal mines, methane acts as a fuel while ventilation air acts as a source of oxygen. The source of ignition may vary from spontaneous combustion, electrical equipment and switchgear, mechanical heat sources, face ignitions due to friction rock-on-rock or from cutter bits and lightning strikes. Under the right conditions, energy of less than 0.3 mJ is sufficient to ignite methane-air mixtures (James, 2007) that can result in a catastrophic explosion. Much research has been done to mitigate the methane explosion hazard by proper dilution, continuous monitoring of methane and elimination of ignition sources. Historical studies indicate that face ignitions are the major cause of explosion in underground coal mining operations worldwide (Belle, Carey, and Robertson, 2012). Statistics shows that most mine disasters were started from a small face ignition, which turned into a major explosion fueled by additional methane and coal dust (Belle et al., 2012). To investigate face ignition hazards, researchers must study potential ignition sources as well as potential explosive atmospheres near mechanical coal cutting operations. Statistical analysis of U.S. coal mine face ignitions reported by the U.S. Mine Safety and Health Administration (MSHA, 2015b) shows that several factors are responsible for face ignitions."

Jan 1, 2016

By K. Ueda

Lead concentrates from Kuroko (black ore) mines, which contain Cu 4 ? 7%, Pb 55%, Zn 3 - 7%, As 0.5 - 0.9% are treated by hydrometallurgical process in order to smelt the product by electric furnace smelting together with other lead resouces from Kuroko. The hydrometallurgical pretreatment involves sulfuric acid leaching at first stage, ferric leaching at second stage. This paper describes the short history of lead recovery from Kuroko and the performance of laboratory test, pilot plant and commercial operation.

Jan 1, 1982

By A. D. Hammond

Vanadium is a transition metal, ductile, silver-gray metal. It is harder than most metals and steels and it has a good resistance to corrosion, it is stable against alkalis, sulfuric and hydrochloric acids. Vanadium is oxidized in air about 660 °C, although an oxide layer forms even at room temperature. The chemistry of vanadium is noteworthy for the accessibility of the four adjacent oxidation states 2-5. In aqueous solution the colors are lilac V2+, green V3+, blue VO2+ and, at high pH, yellow VO42-. Considered to be as abundant as zinc, metallic vanadium is not found in nature, but it is known to exist in about 65 different minerals. Economically significant examples include patronite (VS4), vanadinite (Pb5(VO4)3Cl), associated to the uranium mineral carnotite (K2(UO2)2(VO4)2?3H2O) and in a vanadium mica called, roscoelite K(V3+,Al,Mg)[(Si,Al)4O10](OH)2. Other important vanadium ore oxides are montroseite (V,Fe)O(OH) and corvusite (Na,Ca,K)V8O2.4H2O. Much of the world&apos;s vanadium mine production comes from magnetite-hosted deposit and to a lesser extent, in sedimentary-hosted sandstone. Vanadium is also present in bauxite and in fossil fuel deposits such as crude oil, coal, oil shale and tar sands. In crude oil, concentrations up to 1,200 ppm have been reported. A significant vanadium production comes from the processing of petroleum residues, fly ash and recycling spent catalysts. In 2011, metallurgical applications accounted for 93% of the use of vanadium. Here, an alloy called ferrovanadium is utilized to strengthen steel to be used as rebar in the construction industry, in the manufacturing of axles, crankshafts, gears and chassis in the automotive and transportation industries and in the manufacturing of high-speed tools. In the aerospace industry, vanadium is utilized as a titanium alloy in the manufacturing of airframes and jet engines. The reason for the wide use of vanadium as alloy is its high strength-to-weight ratio, the highest of any engineered material on earth. The major non-metallurgical use of vanadium is in the production of catalysts for the chemical industry. The most commercially important compound is vanadium pentoxide (V2O5), which is used as catalyst in the production of sulfuric acid.

Feb 23, 2014

By Rudolf Fahn

Bentonites are best suited for the preparation of acid activated clays with efficient adsorption properties. They are weathering products of acid volcanic ashes and their natural deposits are world-wide spread. The main constituent of bentonite is the aluminium hydrosilicate nontmorillonite with a high ability to swell. Süd-Chemie owns bentonite deposits in Germany and subsidiaries in Italy, Mexico and Arizona.

Jan 1, 1979

By Issac Douglas, Sheila Devasahayam, John S. Thella, Manoj K. Mohanty, Jeremy Prishmont

The flotation performance of Sodium O, O-diisobutyl Di thiophosphate (referred to as reagent A) was compared with Aerophine 3418A (referred to as reagent B) for floating a complex copper ore grab sample (Ore A). Preliminary test results indicated a cumulative copper concentrate grade of 10.19% with a recovery of 86.31%, which was achieved with reagent A from a feed consisting of 5.32% Cu. The grade and recovery achieved using reagent B are 9.11% and 87.85%, respectively. A comparative analysis based on the preliminary test results indicated that reagent A’s performance is better than that of reagent B at lower concentrate grades, specifically below 12% Cu. However, the flotation performance is better for reagent B at higher concentrate grades (>12% Cu). A more detailed study was conducted to optimize the grade-recovery performances achievable from both reagents on a complex low-grade copper ore sample (Ore B) from Western USA. Test results indicated a copper concentrate with a grade of 5.5% Cu and 78.59% recovery was obtained with reagent A compared to 4.31% Cu and 62.04% recovery with reagent B from a feed consisting of around 0.25% Cu.

Feb 22, 2026

By Landy A. Stinnett

Coal mines in the United States are the most productive in the world in terms of efficient labor employment. This is because of an abundance of workable coal beds, large infusions of capital, improved management practices and continuing competitive pressures. The standard unit of measurement for labor productivity is expressed as tons/manshift, although for underground mines, operators often refer to tons per machineshift. Articles written concerning labor productivity generally focus on measurement techniques, safety considerations, application of technology and training. This article will illustrate by example the impact of labor efficiency (or inefficiency) on the ultimate selling price of coal, f.o.b. mine site. During the past several years, the coal industry has seen significant improvement in labor use. Figure 1 shows the trends in productivity for all active mines in the United States from 1985 through 1994. Productivity in 1985 was 20.1 t/manshift (22.1 st/ manshift). This factor has increased almost linearly throughout that period to 37.5 t/manshift (41.2 st/manshift). This is a 7.2% annual compound growth rate.

Jan 1, 1995

Small-scale flotation tests have been conducted to examine the effect of froth stability on the column flotation of finely pulverized coal. The results of this study demonstrate that the upgrading of coal in a column flotation cell can be significantly improved when froth stability is properly controlled through the manipulation of appropriate operating variables. Several important correlations have been established from the test data. These relationships should prove useful for the design and ore ration of column flotation cells for fine coal processing.

Jan 1, 1991

By A. M. Raichur

Flocculation of fine coal is usually accomplished with the addition of commercially available organic flocculants. Recently it has been shown that biopolymers derived from microorganisms can be used to flocculate coal. The biopolymers flocculate coal efficiently and render the coal surface hydrophobic. The increase in hydrophobicity can be utilized either to separate the coal flocs from mineral matter. It can also be used for reducing the moisture content of fine coal. In this regard, flocculation and settling tests of fine coal with biopolymers and synthetic flocculants was undertaken and the results are discussed here. Also, a transport model was developed for the time-dependent settling tests for fine coal.

Jan 1, 1996

By P. T. Bissert, T. J. Lutz, J. A. Yonkey, G. T. Homce

"Underground refuge alternatives require an air source to supply breathable air to the occupants. This requires pressure relief valves to prevent unsafe pressures from building up within the refuge alternative. The U.S. Mine Safety and Health Administration (MSHA) mandates that pressure relief valves prevent pressure from exceeding 1.25 kPa (0.18 psi), or as specified by the manufacturer, above mine atmospheric pressure when a fan or compressor is used for the air supply. The U.S. National Institute for Occupational Safety and Health (NIOSH) tested a variety of pressure relief valves using an instrumented test fixture consisting of data acquisition equipment, a centrifugal blower, ductwork and various sensors to determine if the subject pressure relief valves meet the MSHA requirement. Relief pressures and flow characteristics, including opening pressure and flow rate, were measured for five different pressure relief valves under a variety of conditions. The subject pressure relief valves included two off-theshelf modified check valves, two check valves used in MSHA-approved built-in-place refuge alternatives, and a commercially available valve that was designed for a steel refuge alternative and is currently being used in some built-in-place refuge alternatives. The test results showed relief pressures ranging from 0.20 to 1.53 kPa (0.03 to 0.22 psi) and flow rates up to 19.3 m3/ min (683 scfm). As tested, some of the pressure relief valves did not meet the 1.25 kPa (0.18 psi) relief specification.IntroductionThe Mine Improvement and New Emergency Response Act of 2006 (MINER Act) was enacted in the United States in the wake of three mine explosions/fires that claimed 19 lives that year. Intended to help improve underground coal mine accident preparedness, the MINER Act includes provisions that target mine safety issues in areas such as emergency response planning, adoption of new technology, training and education, and mine safety standards enforcement (U.S. Mine Safety and Health Administration, MSHA, 2006). Section 13 of the MINER Act specifically directed the U.S. National Institute for Occupational Safety and Health (NIOSH) to provide for research into the effectiveness and viability of refuge alternatives for underground coal mines. This mandate culminated in the 2009 adoption of changes to Title 30 of the Code of Federal Regulations (30 CFR) mining health and safety regulations, requiring underground coal mines to provide mine emergency refuge alternatives and associated components, to provide a life-sustaining environment for persons trapped underground. Such refuge alternatives can be either self-contained mobile units or built-inplace facilities. The regulatory changes also include provisions establishing requirements for MSHA approval of refuge alternatives and their components, and among these provisions are numerous criteria for providing a safe breathable atmosphere under positive pressure within the refuge alternatives. One specific criterion for maintaining a safe refuge alternative atmosphere requires the inclusion of an air pressure relief valve that will activate at a maximum of 1.25 kPa (0.18 psi), or at a pressure above mine atmospheric pressure, in the refuge alternative, as specified by the manufacturer when the breathable air is supplied by a fan or compressor (MSHA, 2008)."

Jan 3, 2018

By D. R. Kelland

A program has been carried out over the last two years to apply the technology of High Gradient Magnetic Separation (HGMS) to the problem of mineral beneficiation and specifically oxidized taconite iron ores. This program, supported by the RANN division of the National Science Foundation, has consisted of a laboratory program at the Francis Bitter National Magnet Lab- oratory at MIT and a pilot investigation at the Hanna Mining Company Research Laboratory. 1 The laboratory tests were conducted using several batch type high gradient separators and a continuous separator with a rotating matrix which was constructed at the beginning of the program. The high field magnets available at F.B.N.M.L. were used for investigations above 10 kG but most of the test work was performed in the range of this field value. Ore samples were contributed by several iron ore companies and consisted of oxidized taconites having goethite and hematite as their principal components.

Jan 1, 1975

By J. C. Irvine

Meramec Mining Company is a joint venture by Bethlehem Steel Corp. and St. Joe Minerals Corp. which mines and pelletizes iron ore at the Pea Ridge Mine. The Pea Ridge property is located near Sullivan, Missouri, about 70 miles southwest of St. Louis. The orebody was delineated in the mid-1950&apos;s by St. Joe during a lead exploration program. The first test holes drilled on the Pea Ridge magnetic anomaly revealed the presence of a large magnetite deposit; further drilling in 1956 and 1957 confirmed that the orebody was mineable, Meramec Mining Co. was incorporated in 1957 and shaft sinking began late in the year. Production commenced in April 1964. The orebody is overlain by about 1300 feet of flat-bedded sediments. It is tabular, about 2600 feet long and up to 600 feet thick. It dips about 80° and is of unknown depth. The ore is mainly high grade magnetite with small zones of specular hematite. The wall rock is a Precambrian rhyolite porphyry. The mine was initially started with five major levels on 150 foot intervals. Crosscuts were driven across the orebody on 190 foot centers. Banks of scopes were mined between the crosscuts by a modified shrinkage stoping method. This was done by undercutting a 40 foot wide by 150 foot long block and blasting horizontal "lifts" drilled on 5 foot intervals. A 65 foot still was left between levels which contained the slushing drift, fingers, crown pillar, and adequate thickness for support. By 1971 a ?lattice? of pillars had been left and mining had progressed to the point that an orderly pillar recovery program was necessary.

Jan 1, 1976

By David B. Costain

Three dimensional surface approximations are important means of evaluating physical and environmental factors that affect surface coal mining and reclamation. Computer approximated surfaces are projected as an array of square grid cells where individual cells define each parameter value respective to locations on the grid. Grid surfaces or grid cells within a surface can be compared or modified through application of standard mathematical functions. Surface approximations can be used to define the quantity and quality of marketable coal and to evaluate thickness and quality of overburden. Surface approximations also can be used to evaluate overburden swell factors wherein changes in post-mine topographic relief are related to expansion of unconsolidated materials in the backfill. Application of computer approximated surface to analysis of approximate original contour (AOC) standards allows an assessment of the quantity and geographical displacement of overburden and the distribution and numerical level of slope.

Jan 1, 1984