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By G. A. Doyle

The White Pine Mine is the second-largest active underground copper mine in the United States, covering an area of approximately 13 square miles in the Upper Peninsula of Michigan. The mine operator intends to initiate in-stope solution mining by circulating a solution of mine water, sulfuric acid, and ferric iron through rubblized ore and recovering copper from solution. As planned, the solution would be retired in the mined-out stopes following completion of solution mining activities. Investigations into the fate of the retired solution mining fluid indicate that the solution, through time, will change from an acidic, metal-rich solution to a near-neutral, reducing solution containing much lower concentrations of metals. Investigations include reaction path modeling (EQ3/6) and laboratory and in-mine experiments. The combination of neutralization and reduction will result in precipitation of most metals, primarily as metallic sulfates, chlorides, and sulfides.

Jan 1, 1996

By Timothy D. Gardner, Christopher Mark

Coal mines in the Illinois Basin have not engaged in pillar recovery for many decades. In large part, this is due to the exceptionally weak nature of much of the roof in the region. But, as room-and-pillar mining is conducted at greater depths, and larger pillars become necessary, recovering them becomes more attractive. Recently a western Kentucky coal mine became the first in recent times to successfully employ full pillar recovery. This paper describes the many challenges that were overcome during the process. From the beginning, the focus was on protecting the miners from roof instability, using cable bolts, mesh, mobile roof supports (MRS), and engineered final stumps. Two short test panels were extracted first, and the results were used to adjust the support pattern and mining sequence. Further adjustments were made based on subsequent experience. To date, seven panels have been recovered without a ground fall injury.

Jul 1, 2023

By Ernesto Maldonado, Zach Agioutantis, Jesus Romero

Reliable prediction of dynamic deformations is important when planning to undermine important structures that cannot tolerate large relative deformations and or large horizontal strains. This paper presents examples of dynamic deformation profiles that include subsidence, horizontal displacements, and horizontal strain for a number of points over a retreating longwall panel in the eastern United States. The prediction points are located at different distances from the excavation rib and therefore present a different response in terms of dynamic movements. The formulation is based on the influence function method as implemented in the Surface Deformation Prediction System (SDPS). Results show that the subsidence development curve may be reliably predicted for surface points in the middle of the panel. However, in cases where points may be affected by the magnitude of the edge effect offset, subsidence predictions may be very conservative, that is, higher than actual movements.

Jul 1, 2023

By B. Hagemeyer

The trend to higher solids paper coating and to neutral/alkaline papermaking is causing an above average growth in the use of calcium carbonate as both a paper coating and a paper filling pigment. These developments are expected to continue well into the 1990s. Thus, calcium carbonate will account for a somewhat larger percentage of total paper pigment volume. Nevertheless, overall growth in paper tonnage coupled with an increase in filler pigment percentages will create a demand for larger quantities of other pigments as well. Kaolin will continue to be the dominant paper pigment by far, with continued growth though at a somewhat slower rate than calcium carbonate.

Jan 1, 1986

By G. L. Mowrey

A new coal interface detection (CID) method is under investigation by the U.S. Bureau of Mines. This novel concept is based on utilizing a passive infrared system (FIR) to measure temperature changes associated with the cutting of coal and adjacent strata. For this method to work successfully, a definite mechanical/hardness contrast must exist between coal and rock. Advantages include that FIR responds instantaneously at the coal-rock interface and it is minimally affected by dust and/or water sprays. Based on preliminary tests, results indicate that the PIR method can be applied successfully in mines having a hard immediate roof.

Jan 1, 1990

By A. K. Clarke

In any treatment process that requires a coarse feed material to be reduced to a fine size by crushing and/or grinding it must be determined whether a wet or dry comminution system should be utilized. All factors must be evaluated in reaching the decision. Among these factors are: 1) Ecology and Plant Environment: Unfortunately in many instances the decision on wet or dry is based on prejudice resulting from an unnecessary fear of dust. The writers submit that this fear, although once justified, is no longer valid because technology and equipment is now available to collect dust to meet any standard. When dry grinding is used it is very often possible to discard a portion of the waste product in a dry state. This will decrease the size of the tailing pond required. As pollution control standards increase it becomes increasingly difficult to clean up water from tailing ponds. 2) Operating Costs: Steel wear is often five or more times greater in wet grinding than in dry grinding. This is mainly due to corrosion. The evaluation of the economics of dry grinding must of course include the air system and dust collection; similarly in a wet grinding plant related pumping and material handling costs should be included. Pumping costs are often overlooked. This assumes water is made to flow for nothing. Pumping can account for 20 percent of the power consumption in the grinding plant. Large scale comparative tests were conducted in a wet and dry commercial plant in 1970. The same ore was used for both tests. With all factors included in both plants the dry system showed lower horsepower per ton.

Jan 1, 1971

By C. J. Im

As market conditions become more competitive, U.S. coal producers are faced with the increasing need to find methods of lowering production costs in their operations. One area worthy of investigation is the additional recovery of fine coal that is normally discarded in the preparation plant waste stream. United Coal Company is currently assessing the capability of the Deister Flotaire, a new application of a column flotation cell, to recover additional, saleable coal from preparation plant waste. This paper presents the technical data obtained to date. Work with a 0.76 m (30 inch) diameter cell installed in a plant shows considerable coal recovery is possible from a nominal 0.595 run (28 mesh) X 0 refuse stream.

Jan 1, 1986

By Rusdian F. Kayadoe, Michael B. Hutahaean, Sandi A. Firmanulhaq

Deep Mill Level Zone (DMLZ) mine is located in Papua, Indonesia operated by PT Freeport Indonesia (PTFI) with approximately 1,500m below surface. The ore body extend 1230m width from northwest to southeast by 300–400m length east-west. The mine currently produces at full production of 80,000 tons per day until 2041. Part of the extension of current active production block and mitigation sits 225 m above the production block 1 (PB1) and 2 (PB2A and PB2B) which located in 2590L, named production block#4 (PB4W and PB4E). As the mining continues at PB1N, PB2A, and PB2B, the cave growth vertically and laterally to south perimeter of the footprint affecting the integrity of PB4W/E footprint. Currently, PB1N and PB2N are in active production whilst PB4E development continues from South against PB1N cave, as can be seen in Figure 1. A slight overlapping between PB1E and PB4E intentionally to promote cave connections between the two caves. Despite low stress model in the PB4E near existing caves, the PB4E cave propagation expected by the large strain and will be propagating in tension failure to the PB1E cave. Hence, designing the drill drives edge and first drawbell location as close as possible to the PB1E cave is necessary to guarantee cave connection. Since PB4 footprint development commenced in December 2021, there have been a substantial cave propagation observed from existing downhole monitoring. As the PB4 footprint designed perpendicular to existing DMLZ PB1 cave, adjustment of the development edge design is necessary to reflect the progression the loosening zone propagation to the South. Final life of mine design for extraction, undercut and ventilation level were decided in October 2023 considering latest update cave (fractured/ yielded) boundary. Numerical model of potential rock mass damage also aids the decision to locate the drift edge design. Predicting the cave progression impact is critical to both production at the existing active blocks and development of the new area. The use of cave shape data from year 2021–2023 gives an insight of the cave shape estimation at the end of 2024 when the undercut drift will be developed. This paper presents actual cave growth of active production blocks and its relative vertical progression impact as the result of drawing in order to plan for acceptable rate and provide mitigation once the minimum acceptable rock mass condition and minimum pillar threshold achieved.

Feb 1, 2025

By C. L. Karr

Establishing suitable control of pH, a requirement in a number of mineral and chemical industries, poses a difficult problem because of inherent nonlinearities and frequently changing process dynamics. Researchers at the U.S. Bureau of Mines have developed a technique for effectively controlling such systems. This technique successfully combines the process control capabilities of fuzzy logic and the search capabilities of genetic algorithms. Fuzzy logic offers an effective mechanism for handling nonlinearities, while genetic algorithms can provide fuzzy logic controllers with real-time adaptive capabilities. This Bureau-developed technique is applied to a laboratory acid-base neutralization experiment. Nonlinearities in the laboratory system are associated with the logarithmic pH scale and the changing process dynamics are due to alterations in pH and buffering capacity input solutions. Results indicate fuzzy logic controllers augmented with genetic algorithms offer a powerful alternative to conventional process control techniques in such nonlinear, rapidly changing systems.

Jan 1, 1992

By K. Rajamani

The word adapt means "to change so that one's behavior will conform to new or changed circumstances." Applying this definition to process controllers suggests that an adaptive controller can change its behavior in response to changes in the dynamics and disturbances of the process. In the minerals industry there are many control cases where adaptive control will provide superior control as compared with more traditional PID (proportional, integral, derivative) control. A typical plant uses as many as 100 to 200 control loops for lprocess regulation. Therefore, the task of initially tuning and then periodically retuning these controllers is a formidable problem, During the time the controllers are "un-tuned", product quality may deteriorate and unstable operations may result. Adaptive controllers are capable of tuning themselves, thus avoiding this problem. The computers commonly used in distributed control systems are easily capable of implementing adaptive controllers. In addition to the possibility of using the control computer to implement adaptive controllers, many distributed control systems will offer adaptive control as a standard feature in the near future.

Jan 1, 1984

By T. F. Torries

The primary merit criteria used by the mining industry is internal rate of return (IRR) rather than net present value (NPV) although NPV is favored by academicians. This paper discusses the problems with IRR and NPV and compares the multi-goal nature of decision makers and their need for information with the characteristics of NPV and IRR. Conclusions are that both NPV and IRR are needed for investment ranking, that NPV suffers the same multiple root problem as does IR.R, and the determination of incremental IRR to reach NPV consistent project ranking is misguided in practice.

Jan 1, 1997

By Rod Heath

The Saskatchewan industry has the advantages of an ore body of a size and consistency unmatched anywhere else in the world, and large, efficient mines with production costs that compare favourably with those in other countries. On the minus side, Saskatchewan is remote from most major markets, and producers face a distribution challenge to reach the offshore markets which is the main focus of this presentation. One of the characteristics of the world potash business is that all of the major sources of production are located in the developed areas of the world, while there is no significant production in any of the highly populated developing countries. The major potash producers are located in Canada and the United States, in West Germany, France, Spain and the U.K., in Russia and East Germany, and in Israel and Jordan. There is currently no significant production in any of the countries in Asia (with the exception of Jordan where a plant is currently in the start-up phase), Africa, Latin America or Oceania, and all of these areas must, therefore, import a11 of their potash requirements from the producing countries.

Jan 1, 1985

By T. L. Myron

To determine the effect of flux crystal size on the production rate and strength of sinter, batch sintering tests were conducted on samples of both dolomite and limestone of various crystal sizes. In addition, calcination tests .were performed on the dolomite and Limestone to determine the effect of crystal size on calcination rate at various temperatures normally attained in sinter beds. The results indicate that flux crystal size does not affect sinter production rate or sinter strength.

Jan 1, 1962

By H. Bradley Johnson

A number of Federal laws affecting safety and health in the mining industry has been enacted and revised over a period of many years. We have tended to classify these laws and their applicability into three categories: 1) coal mines, 2) metal and nonmetallic mines, and 3) mines with Federal supply contracts. With the growing attention which is being given to mine safety by the Federal government, the entire mining industry should keep aware of all developments in the administration of each of these laws.

Jan 1, 1970

By R. W. M. Lai

The study of flotation kinetics was first reported by Garcia-Zuniga1 in 1935. Since then, literature on the subject has grown with the time. 2-19 Although there is an abundance of flotation kinet¬ics models available in the literature to describe flo¬tation systems, they are mostly of academic interest and are seldom applicable for use in the industrial environment. Several reasons contribute to the wide gap in the industrial -application of the academic models. These include: 1) the lack of generality in the model, e.g., the model is limited to certain size ranges; 14 2) the academic models involve complicated mathematics; 5,6,10,11 3) confusion about the order of the flo¬tation rate, e.g., several authors proposed a first order rate model, 1,15,16 whereas the others propagated a second order rate model: 2,17,18,194) the use of an unrealistic rigid value, such as the use of a maximum recovery of 100%, 5,8,19 which is unrealistic in industrial operations; and 5) the use of graphs that confuse the reader rather than interpret information. 2,3,10 This paper intends to introduce a simple and easy to understand empirical flotation kinetics model along with a way of presenting the model in an informative graphical form, which should stimulate the interest of other practical engineers to become concerned with practical application within the mineral industry.

Jan 1, 1982

By L. A. Panek

A new pillar strength formula is presented, incorporating a function P of size and shape, which takes into account the size-shape interaction effect as well as the enhanced strength exhibited by wide pillars. Existing pillar formulas, lacking these capabilities, are not suitable for extrapolating small-specimen test results to mine-pillar sizes and shapes. Interpreting compressive-strength test results as function of P clearly reveals wide-pillar behavior in much old test data. Model relationships are discussed, along with their scaling implications.

Jan 1, 1994

By B. C. Litzinger

Minerações Brasileiras Reunidas S.A. - MBR is a brazilian iron ore mining company geared for the export market. It is controlled by Companhia Auxiliar de Empresas de Minerações - CAEMI through its subsidiary Empreendimentos Brasi leiros de Minerações - EBM which holds 51% in MBR and is formed by CAEMI, the six major japanese steelmills and five japanese trading companies, Universe Tankships, Inc., and Indústria e Comércio de Minérios S.A. - ICOMI. The remaining 49% of MBR's capital are held by St. John del Rey Mining Company, a subsidiary of The Hanna Mining Company. MBR iron ore reserves exceed 1.5 billion tons of high grade ore distributed in 36 deposits located in the so-called IRON QUADRANGLE in the State of Minas Gerais. The Aguas Claras Mine is the largest presently known and highest grade deposit owned by MBR. Other mines such as Pico, Mutuca and Jangada are in operation at a combined rate of production of about 2 to 2. 5 million tons per year. The project consists of mine, railroad and marine terminal (slide). The Aguas Claras deposit, which is located about six kilometers southeast of Belo Horizonte the Capital of Minas Gerais, was selected for initial development. The Sistema Regional Centro of the Rede Ferroviária Federal, through its 6th Division known as the "Central " is responsible for the transportation of MBR ore, and provided the necessary railway construction to connect Mine and Terminal. The Terminal is located on Guaiba Island near the entrance to Sepetiba Bay, at about 120 kilometers west of Rio de Janeiro.

Jan 1, 1974

By A. C. Smith, J. H. Rowland III

The Mine Improvement and New Emergency Response Act of 2006 (MINER Act) established a Technical study panel (the Panel) to provide recommendations on the utilization of belt air and new technology that may be available for increasing the fire resistance properties of conveyor belt used in underground coal mines. The Panel Report recommended use of the belt evaluation laboratory test (BELT) as the method for testing and approval of flame resistant conveyor belts used in underground coal mines. The research conducted to establish the correlation of the BELT with large-scale belt fire flammability tests was done using 91 - 107 cm (36- to 42-in.) wide conveyor belt. Due to today’s coal haulage capacity, the mining industry is using 183 cm (72 in.) and wider conveyor belts. The U.S. National Institute for Occupational Safety and Health (NIOSH) conducted a study to determine if the BELT will also qualify wider belts as fire resistant for use in underground coal mines. This paper describes the results of recent experiments comparing results from using the BELT and the large-scale tests for six different belts.

Jan 1, 2011

By O. D. Christensen

The Carlin Trend is a 60 km (38 mi) long northwest alignment of epithermal, sediment-hosted, disseminated gold deposits. Collectively, these orebodies contained more than 620 t (20 million troy ounces) of gold. The Carlin deposit, located near the center of the Trend, has become the "type" deposit of this class. There are, however, significant differences between the individual deposits. Six subdistricts can be distinguished, based upon geographic, structural, lithologic, alteration, mineralization style, and geochemical characteristics. They are, from northwest to southeast, the Bootstrap, Bluestar-Goldstrike, Lynn, Maggie Creek, Rain and Bullion (Railroad) subdistricts. Regional Geologic Setting The Carlin District is located centrally within the Great Basin Geologic Province. Host rocks for the deposits include sedimentary units that range in age from Ordovician to Mississippian, as well as a Jurassic-Cretaceous granodiorite stock. During the Early Paleozoic, the area that is now Nevada lay along the western margin of the North American continent. A westward-thickening wedge of sedimentary units was deposited offshore in a eugeoclinal basin; these vary from continental shelf carbonates toward the east to fine-grained siliceous clastic and cherty units to the west. Tectonic activity associated with the Antler Orogeny in Late Devonian to Early Mississippian time resulted in the eugeoclinal Western Assemblage rocks being thrust as much as 140 km (90 mi) eastward over time-equivalent transitional to miogeoclinal Eastern Assemblage rocks along the Roberts Mountains Thrust fault system. The leading edge of the Roberts Mountains Thrust plate formed the emergent Antler highland from which siliceous clastic sediment, eroded from the overriding eugeoclinal rocks, was shed eastward into the adjacent foreland basin. Erosional products derived from the overthrust plate are termed the Overlap Assemblage.

Jan 1, 1987

By H. Marshall Farrier

In the past few years the world petroleum industry has increasingly felt the weight of changes in the principal economic factors affecting pro¬fits. As a result of, these changes, it has been necessary for many oil companies to acquire certain new facilities in order to strengthen their competitive positions and thereby protect their tremendous investments in crude oil reserves, pipe line facilities, refining operations, and marketing outlets. Principally these needs have been met by new capital outlays. A supplementary, method of acquiring needed facilities, however, has been to obtain existing facilities through complete or partial acquisition of other companies.' properties. It is this method of meeting competitive pressures with which this paper is concerned. This paper presents a statistical breakdown of the mergers and acquisitions which occurred in the oil industry between January 1, 1954, and October 1, 1959, showing the frequency' with which certain types of properties were acquired in each of the years studied. In addition, it discusses the principal economic conditions which stimulated many of these property trans¬fers, comments on the effects of these mergers on the consuming public, and indicates the types of, mergers and the rate at which they may be expected during the next three or four years. The basic data upon which the statistical analysis presented in this paper is based were taken from several published sources. Obviously they are somewhat incomplete because not all mergers and acquisitions were reported However;, a careful search was conducted through, The Wall Street, Journal, The Oil and Gas Journal, Potroleum Week, and The Oil Daily with the result that the data should be reasonably complete and comparable for each of the years studied, It is believed, therefore, that the statistical analysis which' follows provides a reasonably accurate indication of the general trend in mergers and acquisitions during the period studied.

Jan 1, 1960