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By Christopher D. Henry

Environmental geologic maps of the Wilcox and Jackson-Yegua lignite belts of the Texas Coastal Plain delineate land areas on the basis of their natural characteristics. Criteria used to define map units include substrate, soil, topography, geologic process, vegetation, and land use. The maps are useful in planning and reclamation of lignite mines and in meeting the requirements of State and Federal surface mining laws. Specific applications include identification of land capability, recharge areas and geometry of aquifers, flood-prone areas, areas that may qualify for prime farmland status, and other areas sensitive to lignite mining.

Jan 1, 1982

By Leonard G. Austin

INTRODUCTION Run-of-mine (ROM) coal generally falls into two major groups: that from underground mining (continuous mining machines) and that from strip mining. Continuous miners produce a finer product and strip mining a coarser product that is crushed to produce the desired size. Further size reduction depends on the proposed use or uses for the coal. For example, for pulverized coal power plants as a rough general rule, the coal is ground or pulverized to 80% less than 200 mesh (0.075 mm) before it is blown into the boiler furnace as a coal-air suspension. For solvent-refined coal processes, the desired size is about <30 mesh (< 0.60 mm); in fluidized bed uses, the coal is typically < 8, in. (< 1.6 mm); for Lurgi pressure gasifiers, the desired size is 1 to 2% in. (25 to 63 mm). Coal preparation plants typically work with a coarse size fraction of 6X 1/14 in. (150X32 mm). The past decades has shown a steady increase in the tonnage of coal cleaned, 1 but it seems probable that the next decades will produce much wider applica- tion of deep coal cleaning before use and that the stages of crushing and pulverization from ROM coal to end use will be integrated with coal cleaning processes. Since different cleaning processes work better with different ranges of coal size and the degree of cleaning possible is intimately connected with the size of coal, a systems design engineer will need as much information as possible concerning the size distributions produced by different types of machines and how these can be modified by different ways of operating the machines. In general, the following questions will be of concern: 1.What type of crusher or grinder is best, or most satisfactory, for reducing a given feed size and type of coal to a desired product size? Frequently, the desired product is smaller than some nominal size, but with as few fines as possible, or the fraction in some size range has to be as high as possible. 2. How big does the machine have to be for a given throughput rate? 3. How much electrical energy (or its equivalent) is required per ton of product? 4. How does the size distribution vary with change in throughput rate, and is a control scheme necessary or desirable? 5. Can the size distribution be readily varied if desired? 6. What is the optimum way to operate a machine in a given system? This section will emphasize certain general principles which guide us in answering these questions. PARTICLE SIZING Since particle size and size distribution are the raw information with which we work, it is worthwhile to review the terminology used. In this regard, see

Jan 1, 1991

By Robert A. Jankowski, John J. McClelland, Charles Babbitt

The purpose of this study was to develop guidelines to enable mine operators to maximize longwall dust reductions, while optimizing the use of ventilating air and shearer water consumption. A recent investigation by Foster-Miller Incorporated, under a Bureau of Mines contract, quantified the effect of increased face airflow and shearer water supply on face dust concentrations. A 70 pct reduction in respirable dust levels was achieved at the shearer operator&apos;s position during tail-to-head cutting by an incremental increase in average face air velocity from 83.8 m/min (275 fpm) to 123.4 m/min (405 fpm), while holding shearer water consumption constant. A 60 pct reduction was achieved through an increase in shearer water pressure and flow from 9.1 kg/cm2 (130 psi) at 0.19 m3/min (50 gpm) to 19.7 kg/cm2 (280 psi) at 0.28 m3/min (75 gpm), holding airflow constant. The combined effects of increasing both parameters produced an 85 pct reduction. Optimal usage of ventilating air and shearer water consumption can be achieved by defining a "point of diminishing returns" above which further increases no longer reduce dust concentrations, proportionately .

Jan 1, 1987

By B. Karatzoglou

The penetration of sustainability principles in business practices has introduced the necessity for a simultaneous integrated assessment of the corporate economic, environmental and social performances. Continuous technological, political and legal evolutions indicate that Sustainable Development (SD) principles will soon have to be implemented in all sectors of the Greek corporate reality, among them in the Mineral and Mining Industry. However, the ultimate criteria for the evaluation of a company?s performance remain its profitability and its market value. Managers, shareholders, financial intermediaries, all alike, emphasize and base their decisions on the various accounting produced ratios of return (ROA, ROE, ROCE, Residual Value) included, or produced by data found, in the financial statements of the companies. This paper offers evidence that the traditional accounting ratios discourage the implementation of investment plans that aim at improving the environmental performance of companies and therefore can be inadequate and misguiding for SD applications. International studies have consistently traced a positive relationship between the environmental performances of firms and their financial positions. Yet, the fact that investors tend to reward proactive companies by increasing their corporate values is disregarded by the return ratios, which usually set up the basis for management rewards and bonuses. The book value of the firm assets and owners? equity from which such ratios are produced diverges strongly from the real corporate value, defined as the traded amount for the stock of a firm. There is an urgent need for an adjustment of the return ratios so that they can record the positive economic impact of a more sustainable attitude and encourage decision makers towards this direction.

Jan 1, 2003

By Carl E. Schubert

The application of geophysical technology relative to the exploration, planning, and operation of coal mines is expanding. This is due to the trend of the industry to increase the size of operations, use of mechanized equipment and mining of more difficult coals, where unforeseen conditions can affect mine profitability. Coal is a good geophysical target because of its lower density, higher electrical resistivity, lower seismic wave velocity, and lower magnetic susceptibility in comparison to typical country rock. The more important techniques are well logging, high resolution seismic reflection, seam wave velocity, and radar. These methods can be used to map coal horizons, determine the physical properties of the coal, and identify mining hazards. The methods are not a pancrea however. Their use should be based on a careful assessment of their expected success and cost benefit analysis in comparison with conventional technology, primarily drilling, which none of the techniques presented should entirely replace. In general, the level of technology developed for geophysics surpasses their current level of application to coal problems. In some cases, identifying hazards in advance of mining using seam wave seismic in particular, the state of the art has been developed in Europe and is awaiting fruitful application in the United States.

Jan 1, 1982

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

5.1 INTRODUCTION There are several types of surface ground disturbances, each of which is immediately transmitted to surface structures and causes damage of various forms, depending on the location of the structures in the subsidence basin. Many criteria have also been proposed for defining the potential structural damage. All of these topics will be discussed in this chapter. 5.2 TYPES OF GROUND DAMAGES There are two types of ground damage, continuous and dis¬continuous, that could inflict damages to surface structures. Dis¬continuous ground damage is open fractures of various degrees. Four types of fractures are commonly seen (Brauner, 1973b): 1. Fissures or cracks. Cracks are the most common form of ground damage and range from completely closed to several feet wide. Surface cracks are most prominent when the ratio of mining depth to mining height is smaller than 30 to 50 times mining height. Cracks initiate parallel to, but ahead of the moving long¬wall face at some intervals when the depth-to-mining height ratio is less than 25 to 30. As the face continues to move, they open up and then close gradually, and in most cases eventually close up completely when the face moves farther away. Sometimes when the depth-to-mining height ratio is larger, cracks may initiate be¬hind the face and go through the same cycle. Cracks are also more likely to occur in the hill when the face is moving in the uphill direction. Cracks also occur at or near both sides of the panel edges. Those cracks tend to remain open permanently. When the surface is covered with grass or other vegetation, cracks of less than 1 to 2 in. wide usually do not penetrate it and become invisible on the surface. 2. Steps. A step may occur when the longwall face stops abruptly if the mining depth-to-mining height ratio is less than 20. Steps may also occur along the panel edges. Steps also range from a few inches to a few feet in width and depth. If planes of weakness are oriented favorably, ground will slide along these planes and form steps on the surface. 3. Cave-in pits. These result from local collapse of the ground from the mine level to the surface when the mining depth is less than 150 ft and occur mostly above abandoned mined lands. They may be as large as 40 ft wide and deep. 4. Bumps (compression ridges). Bumps result from ground compression and occur mostly near panel center some time after mining. Bumps of up to 4 ft, but mostly 1 to 2 ft, have been identified. Continuous ground damage refers to the formation of the sub¬sidence basin where continuous nondestructive ground deforma¬tions occur. As mentioned earlier, continuous ground deforma¬tions associated with a subsidence basin include subsidence, slope, curvature, displacement, horizontal strain, twisting, and shearing. 5.3 TYPES OF SURFACE STRUCTURAL DAMAGES Both continuous and discontinuous ground disturbance cause damage to surface structures. A. Structural Damages Due to Discontinuous Ground Disturbance 1. Fissures or cracks. Open cracks can cause dislocation of surface structure if the gaps are sufficiently large so that the struc¬tural elements cannot resist but fail. On the other hand, minor cracks affect only the appearance, and not the structural integrity. 2. Steps. When a surface structure is located on a step, some portions of the structure lose support and become overhung. In the case of a residential house, there will likely be many open frac¬tures in the overhung portions, followed in severe cases by sepa¬ration of the superstructure at the edge of the step. 3. Cave-in pits. If the caved-in pit is larger than the surface structure, the structure will drop into the pit and become unstable. If the caved-in pit is smaller than the surface structure, the struc¬ture may either become overhung or lose support in some portions. In either case, it is unsafe for use. 4. Bumps (compression ridges). Bumps will disrupt roadways or house floor. If located under supporting members of the struc¬tures, it may cause damages. B. Structural Damage Due to Continuous Ground Disturbances 1. Subsidence. Pure subsidence or uniform subsidence over an area does not cause any structural damage. However, if it becomes a topographical low area, it may be flooded with water and make the surface structures unusable. It must be noted that the flat bottom area at the center of the final supercritical subsidence basin does not reach that position suddenly. Rather, as shown in Fig. 3.1, it is subjected to the dynamic surface deformation asso¬ciated with the traveling subsidence basin before it is left behind to be part of the flat-bottom area. Therefore any structure located at the center of the final supercritical subsidence basin must be able to resist the dynamic surface deformation in order not to be dam¬aged. 2. Slope. Ground slope will induce tilting of the structure. Tall structures with small base areas, such as water towers, chimneys, and power transmission towers are most sensitive to ground slope. If the ground slope is such that if after tilting the center of the gravity of the tilted structure falls outside the base area, it will topple, but this seldom occurs. Ground slope will change the designed slope of a buried trans¬portation pipeline, either increasing or decreasing the original slope depending on whether the ground slope coincides with or opposes the original slope. There are maximum allowable final slopes for various types of transporting materials. Ground slope also affects highways and railways. There is a maximum allowable final slope for a railway because tractive effort increases 1/1000 of its weight for every increase of 1/1000 in grade. 3. Curvature. There are positive (convex) and negative (con¬cave) curvatures. When a surface structure is located on a positive curvature, both ends become unsupported, followed by bending upward at the midportion. The top portion is subjected to more severe stretching than the lower one. As a result, vertical cracks with a wider gap at the top occur at the window, door frames, on the walls, and at -the wall joints. V-shaped cracks appear at the

Jan 1, 1992

By Jason Saldanha, Andrew Evans, Jonathan Baber

"INTRODUCTION The need for a new road crossing at Silvertown is the result of three key drivers:- •,Severe congestion and delay at the Blackwall Tunnel and surrounding road network; •,A lack of network resilience and reliability resulting from a lack of alternative road crossings in east London and the impacts of unplanned closures; and •,The need to support substantial economic development in east and south-east London (jobs and homes) These drivers directly informed the main objectives for a road-based river-crossing solution. The traffic-related problems at Blackwall Tunnel are long-standing and before Transport for London (TfL) assumed control for the strategic road network in London in 2000 the Department for Transport (formerly Dept of Transport) had investigated various relief options including a third tunnel bore and new bridge. This resulted in a new crossing alignment being safeguarded (by direction of the Secretary of State for Transport) and this was refreshed in 2001 in favor of TfL. In recent years (since 2009) TfL as part of the East London River Crossings Programme has undertaken detailed optioneering and feasibility work to address the above ‘need’. This led to the conclusion that a new road tunnel would offer the best solution in preference to bridge, ferry or demand management options. In 2012, in response to a formal request by the Mayor of London, the Secretary of State for Transport confirmed a new road crossing at Silvertown as a Nationally Significant Infrastructure Project (NSIP) by Section 35 direction under the Planning Act 2008. This NSIP designation meant that TfL as scheme promoter must comply with the National Rail and Road Networks National Policy Statement (NNNPS) and must seek the necessary powers to build and operate the crossing by means of a Development Consent Order (DCO) under the Planning Act 2008."

Jan 1, 2016

By G. Piegols, J. A. Lombardi

Substantial volumes of cyanide are consumed in precious metals mining due to the purposeful destruction of base metal cyanide complexes and free cyanide to meet surface discharge regulations. This destruction of cyanide resource runs counter to the prevailing social ethic of resource conservation wherein cyanide recovery-and-reuse is considered a more socially responsible cyanide use pattern than systematic cyanide destruction. HW Process Technologies, Inc. (HWPT) has developed membrane based methods for the recovery of cyanide from barren solution as a means to reduce cyanide waste. The HWPT Engineered Membrane Separation (EMS™) system uses state-of-the-art spiral wound membrane elements that are engineered specifically for the treatment of high pH cyanide process solutions. The membranes fully reject WAD CN, SAD CN and most minor metals, and partially reject SCN, Free CN and precious metal cyanide from a high clarity barren solution feed to a small volume EMS™ “concentrate” stream. The EMS™ “concentrate” stream is returned to the process. The large percentage of the EMS™ process feed exits the system as cyanide lean EMS™ “permeate.” The EMS™ permeate, after residual cyanide destruction, polishing, and pH adjustment, is, thereafter, typically suitable for discharge. Separately, the HWPT EMS™-PLS method of cyanide recycling is an internal plant cyanide recovery step that removes base metal cyanides from a pregnant leach solution to a small volume EMSTM concentrate stream. The concentrate stream is then typically processed further for the recovery of metals and recovery-recycling of cyanide. The method makes it economically practical to recover gold from Merrill-Crowe or car-bon plant “fouling” solutions, e.g., those with greater than 400 ppm Cu, as might result from the use of the EMS™ method wherein EMS™ concentrate is constantly thrown back into the mine leach solution pool as part of the free cyanide recycle process, or as might result from the single-pass leach treatment of high copper content ores or concentrates. The EMS™ cyanide recovery method for barren solution treatment is shown to be “economic” for the treatment of clear solutions at the approximately 200 ppm total cyanide level (CNT), and for slurries at the approximately 400 ppm total cyanide level, where economic is defined as a 2 year EMS™ plant payback. The EMS™ plant payback calculation includes the beneficial monetary impacts of gold and free cyanide recycling and the avoided operating cost of cyanide destruction.• The cyanide recovery plant payback period is reduced further when the avoided capital costs for cyanide destruction (EMS™ permeate “clear solution CN destruction polish” only required) and/or metals precipitation are considered.

Jan 1, 2004

By R. D. Grove

The control of Florida phosphate flotation plants is largely based on the visual observations of experienced operators, both in recognizing good and bad froth conditions and in making judgments about the composition of feed, concentrate and tailing streams. Chemical analyses lag the process by at least two hours and, therefore, only assist in recalibrating the operators&apos; vision when major deviations occur. An image analysis system was developed by IMC Fertilizer to improve the accuracy and precision of the composition estimation process. It still relies on the operator taking a representative sample, but provides a measurement in about 15 minutes after that sample is obtained. Background The search for a quick and inexpensive technique for estimating phosphate flotation stream composition continues. There have been attempts at using "wet chemistry," nuclearmagnetic resonance, neutron activation, X-ray diffraction and other techniques reported on in the past several years. None of these have yet found its permanent place in the flotation plants of the Florida phosphate industry. IMC attempted to use wet chemistry to provide 7.5-minute estimates of final concentrate insol and tailings BPL. This was aborted after 36 months of plant operation due to the high operating costs for chemicals and an operator. There was also no significant economic improvement in the plant&apos;s operation. Another factor was the necessity to limit these crude analyses to only a few process streams, which were insufficient to achieve improved plant operation.

Jan 1, 1993

By J. P. Bunch

As the number of environmental laws continues to steadily increase and the economic penalties for contamination problems become more severe, environmental management represents an important management function within today&apos;s U. S. mining industry. The economic impact to a mining company for contamination is not only realized in legal fees and fines but also in the cost of doing normal business. For example, a mining company with contaminated property applying for a loan may be refused because of a lending institution&apos;s reluctance to finance due to liability concerns. Or, an insurance company may decide to greatly increase its annual premiums because of existing or potential contamination problems. One of the main duties of the environmental manager is to seek ways to reduce these types of problems by eliminating contamination or by knowing what problems exist and designing corrective measures to prevent the situation from worsening.

Jan 1, 1990

By D. W. Tuckwiller

Electroplating is a widely utilized but little understood process. The fact that the average person is in contact with dozens of plated items daily without even being aware that they are electroplated is evidence of the success of the process. Although a complete explanation of electrodeposition involves thermodynamics and modern theories of bonding and catalytic reactions, in its simplest form the process conforms to the following description. A metal salt dissolved in water partially dissociates into negatively charged and positively charged ions. In the case of nickel sulfate dissolved in water, for example, a portion of the salt dissociates into positively charged nickel ions and negatively charged sulfate ions. If an electrical potential is applied between two electrodes in this solution, the nickel ions migrate toward the cathode and the sulfate ions toward the anode. The negatively charged cathode has a high concentration of electrons, which combine with the positively charged metal ions to form neutral metal atoms with a stable electron configuration. These insoluble atoms thus form a deposit on the cathode.

Jan 1, 1970

By R. C. Ford, J. Kelsey, S. A. Pierce, M. D. Ankeny

Evaluation of acid drainage risk from spent (leached) ore in arid climatic zones consists of two components: (1) whether residual and secondary minerals will release acid and metals when exposed to rainfall, and (2) whether ambient rainfall is likely to infiltrate, and eventually impact surface or ground water resources. The risk of acid drainage from spent ore at the El Abra on-off copper leach pad operation was evaluated using conventional geochemical methods and unsaturated flow models. Although geochemical testing indicated poor quality water would result from any seepage, unsaturated flow modeling demonstrated that infiltration and seepage were unlikely given the arid climatic conditions. Modeling further demonstrated that the residual moisture content of the spent ore when it is removed from the leach pad controls the risk of seepage. To further reduce the risk of seepage, operational controls were developed and implemented at the El Abra site.

Jan 1, 2000

By James G. Tilton

Throughout the world, sedimentary basins are exploited for many different minerals. Frequently, the extractive methods conflict with one another. A case in point is the proximity of oil and gas operations and the mining of coal. Generally, the interference between the two industries lies in the fact that the reserves over- lie or underlie one another. Mining of coal generally is developed on a rectangular pattern in a horizontal mode while oil and gas drilling is developed on a radial pattern in a vertical mode. Coal mining has exhausted vast acreages in various basins with many of those basins being drilled for oil and gas. Those existing wells create problems by requiring the unrecoverable coal pillars to support the well bore, or to make special provisions in order to mine through an existing well. The system works ... more or less; but there are little or no provisions made for additional drilling unless the vast majority of those new wells are drilled through mined-out sections (gob) of those mines. Many states have rules and regulations governing the drilling of oil and gas wells through gob; but, some companies and some regulatory agencies or personnel have deemed such drilling as a hazard to the mining operations. This paper explores the history, technical standards, and safety aspects of drilling oil and gas wells though the gob of worked-out and active mines. It is the opinion of the author that such drilling can be conducted safely while eliminating the re- quired changes in mine projections and the loss of recoverable coal in the form of well pillars.

Jan 1, 1997

By Donald G. Foot, Jeffrey D. Mckay

Flotation columns have been readily accepted for use in most sulfide flotation plants: however, recently columns are being used in many other areas. Recent improvements in design methodologies have overcome many operating problems and led to improvements in metallurgy. In addition. Physical improvements in column design have simplified their operation while leading to better control. The Turbo-Air External Bubble Generator has provided a method for bubble size control and variation in air holdup and carrying capacity. These have enabled commercial operations to improve grades and recoveries by optimizing performance.

Jan 1, 1989

By S. Fairis Samuelson

Boling Dome. a piercement salt dome in the Texas Gulf Coast basin is (was) the single largest deposit of native sulfur in the Western world. Total sulfur production has been over 81.000,000 long tons and the mine is still in production. Data from over 60 years of operation and 8.000+ wells reveal a salt dome rich in history as well as minerals. Sulfur mineralization and production correlate well with caprock structure and morphology. The occurrence of Mississippi Valley-type deposits in fracture zones is notable in some areas and may warrant additional study. DISCOVERY AND PRODUCTION HISTORY Boling Dome is located in the south- east corner of Wharton County, Texas, 60 miles south-west of Houston. It is a piercement type dome in the Houston diapir province. It was discovered in 1922 when the county surveyor noticed sour gas seeps along the San Bernard River (Haynes. 1942). Several companies including Gulf Production Company. Humble, Texas Company, Sun and others quickly began drilling for oil and gas. Traces of native sulfur were reported in cuttings from many wells penetrating the caprock, but the first commercial quantities of sulfur were not found until Gulf Production&apos;s E.M. Chase 3 and 4 wells were drilled in 1927. Texas Gulf Sulphur, then mining sulfur at Gulf Dome in Matagorda County, secured the sulfur rights from Gulf for $3 million in cash and half of the profits after expenses for development and construction of plant and townsite were met (Haynes, 1942). The drilling results from 200 or so Wells revealed a massive deposit destined to become the largest single source of native sulfur in North America. Original reserves were estimated at just over 46 million long tons and were increased in later years. Production by the Frasch method was begun by Union Sulphur in 1928, and continued by Texas Gulf Sulphur Co. in 1929, and Duval Sulphur Co. and the Baker Williams Co. in 1935. Union produced 8,009 long tons, Duval produced 571,123 long tons, and Baker Williams produced 1,453 long tons. Through its deal with Gulf, Texasgulf acquired the largest and best mineralized portion of the dome and has produced 88,544,466 long tons through 1990, and production is planned for several more years. That amount of sulfur is equivalent to a cube measuring 1,152 feet on each side, or a sulfur highway 1 foot thick, 20 feet wide and 14,479 miles long. Peak production averaged 8,376 ltpd in 1948. A price war between North American sulfur producers and Mexican sulfur producers in 1956, followed by the recession of 1957 and 1958 (Haynes, 1959) coupled with a rapid increase in mining depth to below 700 feet began a gradual production decline that was never reversed (Figures 1 and 2).

Jan 1, 1992

By Harold L. Lovell

The extensive heterogeneity of coal is a fact long recognized by scientists and engineers. However, until recent years the practical implications of such heterogeneity have more often been realized from an undesirable experience than from knowledge or forethought. Variations in the properties of coal, even within the same seam, eventually lead to procedural modifications in mining, handling, preparation and utilization. The concepts considered here propose an enhanced application of information, detailing these properties, realizing the uniqueness of any given coal seam but the practicality of a common approach. Coal preparation practice has been designed primarily for the control of ash and sulfur content to meet market specifications which are similarly specified, Other physical characteristics of size and friability are also commonly employed and, to a lesser extent, properties which are implications of rank. The consideration of petrographic data as indicators of origin, thus total physical and chemical properties, has generally been overlooked as a realistic tool in-the exploitation of coal as a resource. The evolution of descriptive techniques, whether petrographic, physical, or chemical, capable of universal application with any rank of coal, is still beset with problems.

Jan 1, 1968

By C. W. Schultz

Earlier publications from The University of Alabama have indicated that column flotation performance is improved when operating at low pulp levels and when the feed is directed into the froth phase. To validate these early observations a series of tests were performed in which the position of the feed entry to the column and the pulp-froth interface were systematically varied. The optimum grade-recovery relationship was achieved with high feed entry (WA) of column height) and very low pulp levels (<10% of column height). The position of the pulp-froth interface appears to be the more critical variable. When operating in this mode (1. e. at low pulp levels) column flotation becomes. in reality. a froth separation process.

Jan 1, 1991

By Mike Moody

"No matter what type of ore is being extracted from a mine, mucking with front loaders can be accompanied by wet fines that cling to every surface. Once loaded into a hopper or conveyer transfer chute, viscous material can quickly build up on the walls to create bottlenecks, clogging the chute and causing expensive downtime.Clearing material from hoppers, chutes, bins and vessels can be done using manpower and tools on hand, but safety experts recommend considering a solution that prevents exposing workers to potential hazards. Operators at modern mining sites, such as the Eagle Mine, located in Western Marquette County of Michigan’s Upper Peninsula, understand that using specialized equipment reduces worker exposure, offers the safest mode of production and provides the most cost-effective lasting results.“Safety is a top priority for us,” said Ted Lakomowski, lead reliability technician at the Eagle Mine. “When we experienced clogging and downtime at the processing mill, the crew naturally swung into action to resolve it, but we immediately sought a safer long-term solution.”Stope mining for nickel and copperOwned by Lundin Mining, a globally diversified base metals mining company headquartered in Toronto, ON, Canada, the Eagle Mine is the only primary nickel mine in the United States, producing 1.5 percent of the world’s total nickel production. The first operation permitted under Michigan’s Part 632 Non-Ferrous Mineral Mining Law, it opened in 2014 and is expected to produce 163 kt (360 million lbs) of nickel, 134 kt (295 million lbs) of copper and small amounts of other metals over its estimated nine-year lifespan.The company extracts approximately 2 kt/d (2,200 stpd) from the underground nickelcopper mine using a bench-and-fill stoping process. Accessed from the surface by specialized underground trucks, the vehicles carry about 45,400-kg (100,000-lb) loads through a 1.6-km (1- mile) long and 5.4-m (18-ft) diameter ramp shaft descending into the earth at a 13 percent grade. Stoping is a bottom-up method that involves systematically blasting columns of loosened ore that is then mucked by front loaders into trucks and backfilled using cemented and uncemented rockfill."

Aug 1, 2019

By R. J. Sweigard, R. V. Ramani

The effects of postmining land use planning are addressed in this paper. These effects may include savings in reclamation costs and increased value of reclaimed land. However, this may result in greater planning costs and possible delays in production. Therefore, an economic analysis was undertaken in an effort to determine the importance of each potential result and to quantify the overall economic impact of postmining land use planning. A discounted cash flow analysis was performed using a surface mine cost model to analyze the sensitivity of selling price to changes in various postmining land use planning parameters. As a result of this analysis, it was determined that the profitability of a project is most sensitive to delays in production, particularly if the delay occurs after major investments have been made. Many methods have been proposed for evaluating postmining land use alternatives (Sweigard and Ramani, 1981). Both quantitative methods, such as benefit-cost analysis (Brock and Brooks, 1968), and nonquantitative methods have been proposed. The application of one specific analytical method is pursued in this paper.

Jan 1, 1988

By Richard H. Olson

The following discussion will deal with the domestic talc industry only, inasmuch as the writer has had no experience in this field outside of the U. S. This is strictly a geological-mining approach; no attempt is made to assess in depth the effects which milling technology and marketing capability might have in determining the potential of any given talc deposit.

Jan 1, 1970