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By Y. Luo, S. S. Peng

Based on the concept of slope-stability analysis, a formula for determining an important parameter required in the mathematical model for the prediction of mining subsidence in hilly terrain is proposed. The slope geometry and the physical and mechanical properties of the soil at the surface of the natural slope can all be considered in the formula. Incorporation of this new formula into an existing mathematical model provides an integrated approach for the study of ground movement in hilly regions.

Jan 1, 2000

By W. C. Yates

Lack of visibility from cabs of the large haulage trucks used in open-pit mines has become a serious safety problem. This Anaconda research program was conducted to develop a low-cost system for alerting haulage truck operators of the presence of small vehicles in their blind areas. Several systems, developed and tested to help solve this problem, are summarized and evaluated in this paper. As the size of the haulage trucks used in large open-pit mines has increased, so have the blind areas. Mine utility vehicles, pickup tucks and cars become concealed within these blind areas and, thus, become a serious safety hazard. Figure 1 shows the typical blind areas of a 150-ton haulage truck. The areas of greatest concern are those at the rear center and front right corner of the truck. It is within these areas of "no visibility" that numerous small vehicles over the years have been crushed by the large haulage trucks at various mine sites. Although the occupants in most instances, have escaped the vehicle before it was destroyed, injuries and deaths have occurred. The accidents, in most cases, were attributed to negligence or carelessness on the part of the driver of the smaller vehicle, but the problem of limited visibility still exists, and a solution is needed.

Jan 1, 1982

By André Vervoort

After the systematic closure of Europe’s coalfields in the late twentieth century, the emphasis is now clearly on industry’s environmental legacy. One aspect of the latter is the longterm surface movement above abandoned coal mines. The analysis of satellite data shows that the subsidence lasts longer than generally assumed. However, a few years after the flooding of the abandoned underground coal mines, a new phenomenon was observed, i.e., the direction of the surface movement was reversed. The phase of upsidence has already lasted for several decades, and only future measurements will tell how long it continues. A key conclusion is that the regions with maximum subsidence do not necessarily correspond to the greatest upsidence. In other words, buildings and infrastructure are subjected to a different loading from this upsidence than during the subsidence phase. The longterm surface movements have an impact on vulnerable structures in the densely populated regions of the former deep coal mining areas in Europe. These movements create additional damage. This new knowledge is also relevant for mines that are still in operation or future mines that are planned.

Feb 1, 2024

By D. P. Bryan

The identification and-develop¬ment of new construction aggregate resources, the most common mineral mined, is an essential need in this country's growing urban areas. In developing an aggregate exploration program, a thorough geological identification of all potential aggregate resources in an area is still of primary importance but other factors have also to be considered. These include physical properties, end product application, transportation and mining costs, and local government regulations including zoning. The present major aggregate producers are most likely to develop these future resources and are in the best position to initiate comprehensive exploration programs.

Jan 1, 1987

By Jan A. Nemcik

Steel mesh has been used successfully for many years to control friable roof conditions and prevent loose roof and rib material from caving into the roadway. Despite its extensive use, the installation of steel mesh is difficult to automate and many other products have been evaluated as an alternative for skin control. Ideally, the properties of these new products should be similar or better than those of the steel mesh. In particular, development of a strong and resistant shell that minimizes movement along the fractured rock and coal surfaces between the bolt anchors is recommended. A strong surface adhesion and the strength of a reinforced polymer skin can provide the necessary toughening mechanism required to enhance roadway surface support by forming a reinforced polymer/rock surface layer. Most of the Thin Spray-on Liners (TSL) evaluated in the mines are weak with slow curing times, and the plastic mesh currently used to support the coal ribs is relatively weak. Therefore, neither material can seriously compete with steel mesh. Currently, a new polymer product that cures in seconds and forms an instantaneous strata binder that surpasses the properties of steel mesh is under development at the University of Wollongong.

Jan 1, 2009

By Milton H. Ward

The percentage of exploration dollars flowing out of the industrialized countries continues at an all-time high, and this shift in risk money is justified (Samuels, 1990; Bosson, 1977). Clearly, the odds of discovery are greatly enhanced if exploration is pursued in an untrampled and geologically more prospective environment. Unfortunately, such major unexplored areas of the developed world are shrinking rapidly, not just because the lands have already been tested, but primarily because they have been withdrawn from exploration. Experience, however, has shown that foreign investment is not without risks. These include problems that result from working in isolated areas, a lack of infrastructure, untrained workers and an absence of a solid geological data base. While the likelihood of once-feared expropriation is now low, mining enterprises still must take precautions to gain the support of their constituencies, including a variety of governments (local, provincial and central), workers, environmentalists, cultural organizations and local landowners. Is foreign exploration worth the risk? In most cases, Yes! But maintaining tenure and long-term success in a less developed country is only likely with good planning and the use of appropriate safeguards. These include measures such as buying country-risk insurance, building multinational relationships, forming joint investments, developing a broad customer base and seeking local investors in the company (Cobbe, 1979). The primary theme of this lecture is: How a company handles its constituency is critical to long-term tenure in a foreign country. Ideally, a multinational mining company would be so effective in dealing with the local people and managing its relationship with the host government that it would become a preferred employer, preferred over its competitors and over local companies. Historical overview Our earliest ancestors lived in Africa three to four million years ago. The Paleolithic or Old Stone Age, about 500,000 years ago, marked the beginning of mining in its earliest form (Gregory, 1980; Wolf, 1984). Various types of rocks and stones were used for tools and weapons, with flint being the preferred resource for implements. Initially, these materials were collected as stones (eoliths) lying on the surface. Then they came from excavations of flint in limestone beds that were exposed in river banks or naturally occurring excavations. Later, more formal mining developed. No doubt tribes of the Old Stone Age experienced conflict over rights to eoliths, food and land. The question of who owns the land and has rights to its contents and what is fair value for extraction is still the subject of intense debate and, occasionally, open conflict. As time passed, the search for useful minerals required migration from one area to another. Later, voyages from Europe to the New World and travels to other remote regions were funded and supported by absentee investors, kings and such (Rogers, 1976). The primary objective of such funding was to obtain gold, silver, food stuffs and other commodities that could be collected from the new countries. This is still the objective of foreign investment.

Jan 1, 1994

By R. L. Grayson

Following lip on a USBM-sponsored research project, the authors have utilized the knowledge-base structure and system concepts from the Sun Sparcstation-based worker scheduling system of the Mine Management Support System to develop a PC-based application. The new software adopts the nested-window concept to facilitate data collection and modification on personnel, their availability on a shift, and work priorities for a shift as well as to allocate manpower optimally on a work shift and delineate supervisory training responsibilities. The various components of the software are described in detail, along with enhancements made to the original system.

Jan 1, 1996

By J. P. P. Silva

Sodium silicate (water glass) is a modifier reagent widely used in flotation with the function of a depressant or dispersant. The interaction between sodium silicate and mineral surfaces is still not well understood. This investigation aimed to illuminate the sodium silicate action mechanism as a depressant in the flotation of the minerals quartz and calcite. The experiments were done with high-purity mineral samples in the particle size range below 147 µm. The microflotation tests in a modified Hallimond tube showed that, in all systems tested, the efficiency of sodium silicate increased with the concentration. At concentrations above 1,500 g/t, almost total depression (96% for calcite and 97% for quartz) was achieved. The variation of sodium silicate modulus did not alter the quartz flotation performance in the presence of amine (150 g/t). The most efficient depression pH range was observed between 5 and 8. Above pH 10, the depressant action of sodium silicate was negligible. The infrared spectra obtained at pH 7 after silicate contact showed the presence of the groups OH and Si-OH, both suggesting that the adsorption of the neutral species Si(OH)4, as well as siloxane groups (Si-O-Si), attributed to adsorption of polymeric species. Sharing electron pairs is the proposed adsorption mechanism between Si(OH)4 and polymeric species and the surface sites (Si-O on quartz and Ca-O on calcite). At pH 11, the electrostatic repulsion prevents the species adsorption, impairing the sodium silicate action.

By G. Ansong, P. K. Achireko

The authors present a new mineral price model, compare it with time series and naive models, and analyze the effects of the forecasting models on mineral project evaluation. Mineral commodity prices are volatile, which means that the results of evaluation tools that do not treat the stochasticity of metal prices rigorously may be misleading. But, in mine valuation, commodity price forecasts are required to assess the economic viability of a project. In this study, a new mineral forecasting method, called the MNDRVG-MFNN-RM model, which incorporates randomness, neural networks and regression models, is introduced. The MNDRVG-MFNN-RM model, a naive method and time series model were used to forecast gold prices for two successive years for the evaluation of a proposed open-pit mine. The MNDRVG-MFNN-RM model yielded the best results among the three methods. It produced the true optimum pit limits and an optimum pit value slightly less than the true optimum value. The main novelty of the methodology is the simulation and rigorous analysis of the randomness property associated with mineral prices to reduce the estimation and forecast errors, an important contribution to mineral venture evaluation, mine planning and design.

Jan 1, 2000

By Karl P. Norrena, Clayton V. Deutsch

Ore and waste cannot always be visually separated. The distinction between ore and waste may need to be made on the basis of blasthole sampling. Hand drawn dig limits or computer-generated contour lines do not account for uncertainty, economics or equipment. Geometric methods for interpreting grade information such as the polygonal or triangulation methods share the same limitations as contouring. Geostatistical techniques exist for the realistic modeling of grade variations and uncertainty. Decision analysis techniques exist for the binary classification of ore, and waste blocks in the presence of this uncertainty. Block-by-block classification is not enough; mining equipment cannot exercise free selection of blocks. There is a need for procedures to determine optimal dig limits that account for (1) the uncertainty in the grades, (2) the economics of risk-qualified decision-making, and (3) the ability of the mining equipment to dig to specific limits. This paper presents a procedure for optimal determination of dig limits that account for these constraints. Simulated annealing (SA) is used with modest computational requirements because the number of variables is relatively small. The solution of the optimization problem is dig limits that maximize profit under multiple constraints. The method is illustrated with different constraints and tested against hand drawn dig limits in a "Dig Limit Challenge," which illustrates the efficacy of the new method.

Jan 1, 2002

By Owen Kreilis

By the time coal was discovered in Newcastle, Australia in 1791, it was already a most important industrial commodity in European countries. Coal was the first mineral to be discovered in Australia and the first to be mined. Today, coal remains Australia's most important mineral in terms of local use and international trade. The first mechanized longwall in Australia began operation in 1963. It contained self-advancing hydraulic supports and was installed at Coalcliff Colliery, located in the Southern Coalfields of New South Wales. After nine months and production of 53 kt (58,000 st), the unit was withdrawn, largely because of uncontrollable roof weight and with the problems of airborne dust and large coal still unsolved. Basically, roof support was insufficient. The European design of the Coalcliff longwall was inadequate for Australian conditions. Another type of support with modifications was installed and began operation at Kemira Colliery at Wollongong, New South Wales, in 1964.

Jan 1, 1995

In 1993, the United States' economy grew at a rate of about 3%. The Gross Domestic Product rose to $6.4 trillion. With more than 258 million people - 599,000 in mining including petroleum - the United States has more than 100 million dwelling units and more than 190 million licensed motor vehicles. New private housing starts rose 7% to 1.3 million units, new car production fell 3% to 5.5 million units and truck and bus production rose 21 % to 4.9 million units. The rate of inflation was under 3% and the prime rate of interest 6%. The Producer Price Index (1982 = 100) was unchanged from 1992 for fuels and re¬lated products and power at 80 and met¬als and metal products at 119, while chemicals and allied products rose 2% to 128 and non-metallic mineral prod¬ucts rose 2% to 120. The merchandise trade deficit rose 27% to $116 billion.

Jan 1, 1994

By Shouci Lu, Keji Sun, Dianzuo Wang, Yiqun Li, Chuang Jin

The dephosphorization of iron ore and reduction in Fe loss in process are currently the foremost technological challenges facing the mineral industry of Meishan Iron Ore. These problems can be resolved to a greater extent by an apatite flotation process which depends on selective flotation reagents. The primary objective of this research work is to develop new type of flotation collectors for dephosphorization of weak magnetic iron ore. Detailed discussion is given on the influence of collector dosage, pH, dispersants and pulp temperature on the flotability of apatite, siderite and hematite using the collectors of Oleyl sarcosinate(OSS), Alkyl polyoxyethylene ether phosphate (AEP) and the mixtures of OSS and AEP A key feature of the flotation was the use of the mixtures of OSS and AEP as a selective collector for phosphate. The effects of chemicals and operational variables on the phosphorus flotation from the weak magnetic iron ores have been investigated. The test results shows that floating the phosphorus minerals with new type collectors can reduce the phosphorous content in the flotation concentrate to an acceptable level of less than 0.20% P with increased Fe recovery.

Jan 1, 2002

By G. Atesok, M. S. Celik, G. Onal, I. Yildirim

A new coarse cleaning device, the Stripa, has been developed for processing of coal in the size range of -100+10 mm. The Stripa is an auotogenous heavy medium separator originally developed for processing of iron ores. Although it has been employed in concentrating ores such as chromite, it has not been applied in coal cleaning. In this study, a pilot plant scale modified Stripa and its counterpart alternative, a diaphragm jig, are compared using subbituminous and lignitic coals. The separation performance of the Stripa and the diaphragm jig has been established in the light of washability properties of the coal samples. Comparison of the performance of the Stripa with that of the jig indicates that the Stripa can be used in coal preparation circuits as an alternative to jigs in the size range of -100+10 mm. Simplicity, low initial investment, and low operating and maintenance costs make the Stripa a plausible candidate for coarse coal cleaning. More importantly, Stripa due to its short residence time, has a superior capacity over jig.

Jan 1, 1995

By Ronald C. Bethard, Kenneth W. Ely

The liberation of methane during underground coal mining causes serious safety concerns. During a mining cycle, with mechanized mining equipment, thousands of cubic feet of methane are released from coal seams, discharged to return air courses, and vented to the atmosphere through mine fans. This has been the traditional way of removing the explosive hazards of methane gas from the mine. Through horizontal and vertical degasification techniques, this hazard can often be handled in an equally safe and much more profitable manner. Basically, degasification allows for the controlled reduction of inseam methane content of coal prior to its mining. It is the responsibility of mine management to evaluate these degasification programs and ensure that the program itself does not introduce some new risk to the mining process. The removal of methane gas from underground coal mines using horizontal and vertical degasification is a relatively new concept. Products and systems used in degasification continue to evolve. Site conditions vary also, so no one system or equipment can be said to be the safe answer for degasification in all situations. A constant process of cooperation and evaluation by mining and degasification management should result in a safer and more profitable mine.

Jan 1, 1989

By James Warren Andrews, Philip C. Nyberg

The regulation of exposure of underground personnel to radon and its daughter products has significantly changed since the 1950's. The U.S. Bureau of Mines - Mining Enforcement and Safety Administration (MESA) - Mine Safety and Health Administration (MSHA) sequence of standards and regulations have lowered the maximum allowable occupational exposure and now the new Environmental Protection Agency (EPA) National Emission Standards for Hazardous Air Pollutants, effective in 1990, have further regulated uranium mine emissions. Under the authority of Section 112 of the Clean Air Act (42 U.S.C. 7401), the EPA has set regulations for the control of radon (Rn-222) emissions from underground uranium mines as well as other sources. Since the venting of radon from the mine atmosphere to the outside air is a major component of the miner's protection, and since this is the first quantitative effort to limit gaseous mine emissions to the environment, it was felt that it would be useful to examine the implementation of the EPA regulation at working mines. The concern was not only for determining compliance with the regulation but also for observing what effect the rule might have on mine air quality and thus on worker exposure. The regulation is stated in terms of the maximum permitted radiation dose to the closest potentially exposed individual, which is calculated from a computer program supplied by EPA and radon emission rates measured by the mine operator. Relative proximity to nearby populations determines the allowable magnitude of mine exhaust ventilation emissions. For some mines this is a serious operational constraint.

Jan 1, 1991

By Andy Thompson, Frank Perrone

"As part of the Metropolitan Transportation Authority’s $10.5bn East Side Access Project in New York, 3,200 m of tunnel had to be constructed in rock, mix face and soft ground conditions beneath one of the largest passenger railroad junctions in North America, handling over 780 trains per day. The use of risk based decision making tools was essential in developing the bespoke contract framework that was adopted as well as making informed decisions once excavation commenced. This paper will outline the risk management process adopted, discuss the risks and mitigation strategies adopted and comment on the impacts of this approach on the as built Project cost and schedule. In particular, the paper will outline the unique approach used to establish the baseline against which the Contractors performance would be measured as the selection of a Slurry TBM to excavate the tunnels was considered to compromise the effective use of a Geotechnical Baseline Report. BACKGROUND AND CHALLENGES Contract CQ031, Queens bored Tunnels and Structures was awarded in September 2009 to a joint venture of Granite Northeast/Traylor Brothers/Frontier Kemper (GTF JV) for $717.6m following a negotiated procurement process. A robust approach was taken with regard to the management and payment for risks associated with the construction of these tunnels. Risk assessments were carried out during the design phase and a risk register was developed prior to procurement. During the procurement phase close attention was paid to ensuring that the allocation and pricing of known risks, together with mechanisms for managing future risks were clearly defined between the MTA and GTF JV.In comparison to the excavation work in Manhattan, which was performed in competent hard Manhattan schist, the tunnels in Queens were excavated predominantly through soft ground with a high water table and complex environmental conditions. Not only did this require the use of pressurized face TBM technology, a first in New York, but also a re-evaluation of the contractual mechanisms used to manage the hard rock excavation contracts for their appropriateness to the soft ground tunnel work."

Jan 1, 2016

By Winthrop F. Watts, Robert W. Waytulonis

During the 1980's. the Mine Safety and Health Administration (MSHA) proposed new regulations for the use of diesel equipment in underground coal mines, and the National Institute for Occupational Safety and Health (NIOSH) recommended that whole diesel exhaust be regarded as "a potential occupational carcinogen", and that reductions in exposure to exhaust pollutants would reduce excess risk. During the same time, the Bureau of Mines tested new emission control technology to minimize diesel emissions. The objectives of this paper are to discuss the major issues regarding diesel exhaust emissions. especially diesel particulate matter (DPM) , and to highlight emission controls that will be available. DPM is a potential health threat because it is respirable in size and is composed of nonvolatile carbon with adsorbed or condensed compounds. These compounds include potentially mutagenic or carcinogenic hydrocarbons such as polynuclear aromatic hydrocarbons and sulfates. DPM contributes to the degradation of air quality in mines with typical mean concentrations ranging from 0.2 to 1.0 mg/m3. In addition to adequate ventilation, control of DPM can be achieved by implemention of improved work practices, regularly scheduled engine maintenance, and emission controls.

Jan 1, 1991

By Stephen H. E. Phillips

Geological and hydrological conditions in the strata overlying the Salado Formation vary considerably in the Carlsbad, New Mexico area. The first four shafts sunk at international Minerals and Chemical Corporation's property have been located in competent and essentially dry conditions, while other shafts on adjacent properties have had such adverse conditions that ground freezing has been chosen as the water and ground control technique for shaft sinking. At the location of the IMC No. 5 Shaft there has been extensive-erosion and salt dissolution in the Rustler Formation which has led to collapse of some zones of the strata. Both ground freezing and pregrouting were considered as alternative methods of stabilizing the extremely poor ground conditions and controlling the potentially very heavy water inflows it was decided that pregrouting the shaft was feasible and would offer substantial cost and time saving over a ground freezing technique. This paper describes the pregrouting techniques used and illustrates the requirement for flexibility in a grouting program so that it can be codified to reflect any new or additional information which is obtained during the progress of the grouting.

Jan 1, 1984

By Jonathan J. Owen

We will describe modifications to air-sparged hydrocyclones (ASH) that enhance collisions and reaction of wastewater contaminants with sparged gas. These new ASH-based reaction chambers are combined with flotation tanks that are designed to optimize separation of bubbles and particles from water. In combination, these systems have achieved unprecedented removal of contaminants from industrial wastewater and process water while requiring smaller footprints with lower capital and operating costs. Real-world examples of chemical and nonchemical water treatments that demonstrate the outstanding flexibility and applicability of these systems are shown. Design enhancements that resolve the operational problems of traditional ASH are discussed.

Jan 1, 1999