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By V. F. Swanson

A mathematical model for free and hindered settling of minerals was developed. This paper describes how to apply the model in designing systems, such as fluidized bed, elutriation, mixing pumping systems, involving solids and fluids.

Jan 1, 2000

By A. Goulsbral, D. Harrison, R. Dunne

A programme to reduce cyanide consumption at the New Celebration Gold Mine, situated 32kms South of Kalgoorlie, Western Australia, commenced in the latter part of 1990. Cyanide speciation studies at the time identified that the major loss and consequently consumption was due to the hydrolysis of cyanide, The use of artesian hypersaline waters of high magne­sium content on gold plants in Western Australian Goldfields has meant that economically viable operating pH values during cyanide leaching are around 8.9 to 9.5. The high ionic strength in these waters does to some degree retard the hydrolysis reac­tion. Notwithstanding this, the formation of hydrogen cyanide and its loss due to volatilisation is the cause of the major loss of cyanide on most gold plants in the Kalgoorlie Goldfields. This paper discusses the aspect of oxygen addition during cyanide leaching to decrease cyanide consumption and increase gold recovery.

Jan 1, 1996

By Roy L. Klein

The production of synthetic fuels from coal has been pioneered by South Africa. South Africa made a decision in 1975, due to the threat of an oil embargo, to proceed with the construction of Sasol Two, then followed by Sasol Three. South Africa has large coal but little indigenous petroleum reserves. The indirect coal liquefaction process used by Sasol since 1955 is the only commercially demonstrated method available for producing transport fuels from coal. The new plants consume 27 million tons per year of coal from a single mine that now produces transport fuels in sufficient quantities for energy independence.

Jan 1, 1983

By Walter C. Labys

This paper reports on recent modeling efforts to analyze the eastern U.S. steam coal market with a cross-sectional econometric as well as a quadratic programming approach. The background to coal modeling is examined first. The particular aspect of the steam coal market to be modeled are then presented and the corresponding coal model described. Both empirical results and rigorous mathematic pertubation analysis are presented. Conclusions are then drawn regarding potential modeling applications in the policy area.

Jan 1, 1979

By D. R. Zeni

Current mine development requires the safe, 'expedient, economical construction of vertical shafts for ventilation and access in diverse ground conditions. Advancements in large diameter shaft drilling have lead to exceptional mechanical refinements of shaft drilling technology. The author traces the history of the equipment and methods employed by the large diameter shaft drilling industry and explores likely paths of future development. A few case histories are cited to illustrate the adaptability of shaft drilling as a versatile tool for advanced worldwide mining operations. Safety, schedules, cost, environmental impact, and capability are discussed to assist the mining engineer in the investigation of feasible projects.

Jan 1, 1994

By J. M. Keane

SMEThis loaner is concerned with important criteria relative to the design of small flota¬tion concentrators. For the purpose of this discussion a small flotation concentrator is defined as a facility having a designed ore feed rate of 1,000 metric tons per day (MTPD), or less. The decision to design and construct a small flotation concentrator is the culmination of a series of logical steps relative to the ex¬ploitation of a potential ore body. The information required for a rational and timely decision regarding plant design and construction is usually contained in a feasibility report. The information required in a thorough feasibility report has been summarized (1) (2) as follows: Type of mine or plant and proposed daily, monthly, and yearly production of all intermediate and final products. Quantity of indicated ore reserves. Location of project illustrated by a map showing surroundings, trans-portation facilities, and existing utilities.

Jan 1, 1980

By John C. Brower

The purpose of this paper is to examine the Gays in which- the policies of the U.S. government, mining companies and third world countries affect each other with regard to the availability of minerals. The interaction involves U.S. policy towards the mining industry, the policies of the companies themselves, and the policies of third world countries towards the U.S. and multinational companies. It is assumed in this discussion that U.S. policy will continue to be to seek certain minerals from abroad rather than attempt to develop domestic sources for all its requirements. This would seem to make sense both from the standpoint of cost, and for preserving what domestic resources there are so as to maintain some degree of market leverage. In today's jargon, this means greater dependency on the "third world", which, for this discussion, includes virtually all the nations in Africa, South America and Asia. Concern for availability raises the important distinction between dependency and vulnerability, and as the Director of the Bureau of Mines has pointed out, the two are not the same. Dependency is not neccessarily a bad thing; it is vulnerability that counts (Norman, 1980)

Jan 1, 1982

By Clarence A. Johnson

The discovery of the Prudhoe Bay field temporarily reduced interest in the development of coal conversion processes, but interest is being re¬newed by the current energy crisis. According to M.A. Wright, Chairman of the Board of Humble Oil and Refining Company(l), the reserve in the Prudhoe Bay bield has been confirmed to be about 10 billion barrels. At first glance this appears to be an extremely large reserve which will eliminate supply problems for the United States for some time. This feeling of security is lost when one realizes that by 1980 the world will consume the reserves of a Prudhoe Bay or a Libya, or Venezuela in less than a year, based on the recent predictions of U.S. and world reserves made by Eastman-Dillon, Union Securities Company(2). Recent forecasts of U.S. demand and source of supply made by Kenneth E. Hill of Eastman-Dillon are shown in Figure 1. This forecast shows a decline in domestic supplies (excluding Alaska) after 1973, with the total domestic supply leveling off in 1975 at about 13 million barrels per day. Since the predicted demand increases from about 14 million barrels per day in 1970 to about 20 million barrels per day in 1980, about 35% of domestic consumption must come from imports or non-conventional sources by 1980. More imminent is the shortage of low sulfur fuel oil which has been created by the new, tough air pollution regulations that are basically legis¬lating eastern coals out of the market. As an alternate to importing large quantities of low sulfur fuel oil or importing and desulfurizing regular fuel oil, one of two domestic solutions is possible: stack gas clean-up or solids fuel pretreatment. Stack gas clean-up may be the cheapest approach for old installations, but fuel pretreatment has real advantages for new installations. Coal pretreatment at the mine could eliminate all solids fuel handling

Jan 1, 1972

By Robert J. Russell

The importance of grinding as a unit operation in all industry has caused much effort to be expended toward improving the facility with which grinding can be done. Endeavor has continued nearly 100 years to formulate laws governing crushing and grinding. This has not been without controversy. However, grinding is an experimental science and our useful knowledge originates in experience. The recorded experience is grinding history. Today, many types of size reduction equipment, each with variations, are available to industry. Frequently, more than one type of grinding equipment will meet a requirement of grinding. However, an economic evaluation of installation and operating costs generally indicates a preferred type. The selection of grinding equipment requires' a consideration of the purpose in grinding, the characteristics of the material to be ground, equipment available for grinding, and the manner in which it can be applied best.

Jan 1, 1960

By T. D. Barkand

A recent coal mine elevator accident resulted in serious injuries to four passengers. The miners struck the ceiling of the elevator car as it collided into the overhead structure at an estimated speed four times faster than normal. In response to mine hoisting accidents, safety authorities have required additional protective devices on new and existing mine hoists and elevators. This paper examines supplemental safety circuits and new devices designed to provide ascending car overspeed protection on mine hoists and elevators. These devices provide needed protection that eliminates the hazard or significantly reduces the potential of a mine hoisting accident.

Jan 1, 1995

By D. G. Feuerbacher

Maximizing production of oil from sandstone petroleum reservoirs is aided by use of non-damaging drilling and workover/completion fluids. Various tests, such as X-ray diffraction, scanning electron microsccpy, petrographic microscopy, porosity and permeability are conducted on core samples. Several fluids are selected, on the basis of these results, for return permeability tests. A report is then written giving the results of all tests, potential reservoir problems, and recommended practices for exploiting the reservoir.

Jan 1, 1983

By V. Duddempudi, B. Goertz, J. Brune, G. Bogin, F. S. Barreto

"INTRODUCTION In designing a new pneumatic Dust Sampling Device (DSD) for coal mines, it was essential to analyze the air and particle flow inside the device in detail using Computational Fluid Dynamics (CFD) modeling. Several CFD models were developed to simulate the air and dust flow and sample collecting process of the DSD. These CFD models were developed to assist in the design of the DSD instrument prototypes for laboratory testing. Nozzle and injection parameters such as geometry, air velocity and pressure, were varied across a wide range to obtain the optimal settings to accurately simulate the fluid dynamics of the multi-phase flow within the DSD. Accordingly, these parameters were used as a guide for the design of the DSD and to verify the dust scouring dynamics, which is designed to represent the dust entrainment during an actual methane or coal dust explosion. BACKGROUND The 2010 explosion at the Upper Big Branch mine has demonstrated the destructive violence of a coal dust explosion. A major contributing factor for this disaster was that the mine operators did not have a reliable, direct-reading method to collect mine dust and determine inert content and combustibility. This led to the development of a new prototype handheld, pneumatic mine dust sampling device (DSD), which blows a puff of air and entrains the mine dust by mimicking the entrainment process during a mine explosion. A computational Fluid Dynamics (CFD) model is used to analyze the air and dust flow inside the DSD. The objective of the CFD modeling effort is to find the optimum design of the DSD prototype, nozzle orientation, air pressure and pulse length by analyzing and varying these parameters so that the scouring action collects a valid, representative and repeatable mine dust sample. CFD MODEL DESIGN Figure 1 shows a wireframe image of the DSD which is utilized in the setup of the CFD model. The DSD has a triangular cross section and is 10 cm wide. Two nozzles with cross-sectional dimension of 2.8 cm by 0.25 cm act as inlets at the narrow end of the triangular cross section. The CFD model includes a reference plane 6 cm away from the nozzle to measure the quantity of dust collected. The geometry shown in Figure 1 was created for the model and it matches with the design of the actual device shown in the figure 2. Symmetry, along the plane X-Y through the center of the device, is used to reduce the number of computational cells in the CFD model. Figure 2 shows the prototype device used for experimental testing. CFD MODEL SETUP Figure 3 shows a hexahedral mesh with a cell size of 0.8 mm and the total number of cells is around 650,000. The ANSYS Fluent® pressure based solver with a transient case was used with a total duration of 40 ms. The 40 ms simulation time is based on experimental measurements to capture the injection of air and initial scouring of dust."

Jan 1, 2016

By E Mutaz, M Bahaaddini, D J. Williams, M Serati

The contribution of the mining industry to the global economy has reached (and gone beyond) $1,800 billion in recent years that necessitates (more than before) the need to ensure workability, viability, health, and safety of mine sites and workers to meet the ever-increasing global demand for mineral resources. Amongst the many challenges facing the excavation industries, rockburst and spalling failures in deep mines in hard and brittle rock formations are yet happening that are still deemed as unsolved problems. During unconfined compressive testing of brittle rocks, microcracks initiate at approximately 0.3–0.5 of the peak strength (which is commonly known as the Crack Initiation stress level) mainly in the direction of the major principal stress, then grow unstably and coalesce to form macro fractures at approximately 0.7–0.8 of the peak load at a so-called Crack Damage stress threshold. From a stress-strain perspective, the crack damage stress threshold () is associated with the reversal point of the volumetric strain, which is also proved to be strongly affected by the intermediate principal stress. This paper extends the previous studies on the impact of true triaxial loading conditions on the CD stress level in high porosity rocks, and introduce a new Crack Mode-Changing Stress (CMCS) defined as the minimum principal stress required to change rock fracturing from splitting to a sliding failure mode. A large number of experiments on sandstone specimens were carried out at different true triaxial loading conditions and the effect of principal stresses on the CI and CD as well as CMCS were studied. The results show that not only the intermediate principal stress, but also the minor principal stress can significantly affect the CD and CMCS thresholds.

Apr 26, 2022

By H. M. Giegerich

About Cominco Only the original Broken Hill zinc deposit in Australia is larger than Cominco's Red Dog deposit. Indeed, the third largest zinc deposit in the world is Cominco's own Sullivan mine in British Columbia. The production plan at Red Dog is based on mining 1.9 Mt/a (2.1 million stpy) or ore, to produce 635 kt (700,000 st) of zinc and lead concentrates. At full production, Red Dog will be the largest zinc mine in the Western world. It will also be one of the lowest cost producers in the Western world. And Red Dog will be one of the first major hardrock mines to operate in Alaska in modern times. The Red Dog project will be the third and largest of Cominco's Arctic mining developments in the past 13 years. The company's Black Angel mine in Greenland started up in 1973. And the Polaris mine, high in the Canadian Arctic, began production in 1982. Red Dog is one of the world's great mineral deposits. It is a unique combination of large size, high grade, and a waste-to-ore ratio less than 1:1. The present mineral reserve (Table 1) is estimated to be 77 Mt (85 million st), at a grade of 17.1% zinc, 5% lead, and 82 g/t (2.4 oz per st) of silver. Mine life is estimated at nearly 50 years. Cominco is the largest producer of lead and zinc in the Western world. Cominco's smelter in southern British Columbia is the largest lead and zinc plant in the west. Cominco also produces copper, steel, tin, gold and silver, along with potash, ammonia, urea, and phosphate fertilizers. But Cominco's major products are lead and zinc. At present, Cominco produces more than 10% of the Western world's needs for these metals. Background-Red Dog The Red Dog mineral deposit is located in northwestern Alaska, about 960 km (600 miles) by air from Anchorage, Alaska's largest city. The Red Dog region is home to more than 5000 people living in 11 villages. The largest village is Kotzebue, with a population of about 2500. The village is located about 144 km (90 miles) southwest of the mine. The country around Red Dog features rolling hills, leading into mountains to the north and east. The deposit, at an elevation of 305 m (1000 ft), is in permafrost. But the area is not nearly as cold as that encountered in the Canadian Arctic, or on Alaska's North Slope. At Red Dog, the permafrost is relatively fragile. It can be thawed fairly easily, a factor in engineering designs. Red Dog Creek flows through the mineral deposit. One of the natural phenomena at Red Dog is the presence of significant heavy metal contamination in the creek. This has eliminated all fish in the vicinity of the deposit. The contamination, and resulting mineral stain, led to the discovery of Red Dog. The staining is caused by rain and snowmelt. This leaches the heavy metals from the mineral zone, which comes right to the surface in many places. As mining progresses, this surface mantle will be removed. This will

Jan 12, 1986

By J. S. Jaspal

Mining of thin coal seams is both difficult and uneconomical. As a result, most of thin-seam coal reserves in the U. S. are not being mined. It is estimated that nearly 910 Gt (K. Unrug, 1985) of coal reserves exist in 355 to 710 mm thick seams. The Bureau is attempting to develop new techniques for mining 150 to 1065 mm thick coal seams. This paper summarizes the research work on existing thin-seam mining techniques, testing on small and full scale physical models of the Bureau slot mining concept, and computer modeling of the full-scale process.

Jan 1, 1992

By James W. Mitchell

On December 2, 1942, a scientific team lead by Nobel Prize winner Enrico Fermi first initiated and controlled a self-sustaining nuclear chain reaction. This historic event occurring beneath the stands of the University of Chicago football stadium instantly created an entirely new and tremendously broad area of technology. Indeed, the event probably changed the course of world history and considering the curret energy shortage, it probably came none too soon. Following many technological breakthroughs in the ensuing years, this event led to the first full scale nuclear fueled electric generating plant. In December, 1957, the Shippingport Nuclear Power Plant became operational and the United States had entered the era of the nuclear fueled electric generating station. Today, only fifteen years later, there are some thirty-five operating nuclear power plants in the United States with another 56 under construction and 116 on order. Still, we are only scratching the surface of this tremendous energy source. In 1970, less than one-percent of the total electric generating capacity in the United States was nuclear fueled. By 1985, it is projected that 45% of our generating capacity will result from nuclear power plants. These projections are based upoa statistics of six months to a year ago and considering the current energy shortage and recent attempts by the United States Atomic Energy Commission (USAEC) to speed the licensing process and encourage standardized plants, the contribution of nuclear power to our total generating capacity may be even greater. In summary, it is obvious that nuclear power is now, and will continue, playing an important role in our future. Those factions of government, industry and the professional community charged with fully developing this tremendous energy source must deal with it rationally, logically and expediently. The various environmental considerations in nuclear plant siting play an important role in the overall plan.

Jan 1, 1974

By Alfredo Valdivia, Jesus Schabib, Vojtech Gall, William Cao, Curt Cicileo, Andrew J. Thompson

"The East Side Access Project (ESA) involves the construction of geometrically complex underground structures including a large number of caverns and bifurcations. Initially conceived as dual lined structures with either traditional concrete or shotcrete final linings (SFL), construction economy, advances in concrete placement technology and scheduling among others led to a wide use of what is referred to as freeform or pneumatically applied concrete (PAC) for the construction of tunnel final linings. PAC is a method of applying concrete without using formwork, where a wet mix concrete is pneumatically installed to encase reinforcement to full lining thickness. PAC has been widely adopted at ESA well beyond initial expectations. The paper addresses the design and construction aspects of the PAC method and contrasts it to traditional SFL lining placement. The experience made provides guidance for future PAC and SFL applications. THE EAST SIDE ACCESS PROJECT AND USE OF FREEFORM CONCRETE The Long Island Rail Road (LIRR) currently transports commuters from Long Island into Manhattan, terminating at the already congested Penn Station on the west side of Manhattan. Once completed, the ESA Project will provide LIRR commuters direct access to the east side of Manhattan underneath Grand Central Terminal. The ESA Project will help alleviate the congestion at Penn Station, which currently accommodates New Jersey Transit, Amtrak, and LIRR lines; reduce travel time for LIRR passengers traveling to the east side of Manhattan and facilitate connections to the New York City Transit (NYCT) Subway System and Metro North Rail Road. The construction includes mining and lining of new tunnels and facilities under Manhattan and Queens. The tunnels run from Queen’s Sunny Side Yard through the existing 63rd St. Tunnel, underneath Manhattan’s Park Avenue until termination at 37th Street. Differing types of tunneling methods and final lining systems are being used depending on the ground conditions, geometry and size of the excavation, site constraints and functional requirements. Mining of the Queens segment of the ESA Project involved soft ground tunneling by pressurized face tunnel boring machines, cut and cover construction, and conventional tunneling. The Manhattan segment of the ESA Project involves mining in hard rock by tunnel boring machines, drill and blast, and road header."

Jan 1, 2016

By D. M. Bodily, V. J. Hucka

INTRODUCTION Interest in the recovery of methane from coalbeds has increased rapidly over recent years, because of its potential as an energy resource and to alleviate pollution and safety problems. The resource base of coalbed methane in the United States has been estimated at 11.2 Gm3, roughly equivalent to 20 years consumption (Mroz et al., 1983; Kuuskraa and Brandenburg, 1989). Methane contributes to the adverse environmental impacts of global warming, tropospheric ozone formation (smog), and potentially stratospheric ozone destruction. Association of methane with coal has always presented a safety problem in mines due to the potential for explosions. The rate of release of methane depends on the amount adsorbed by the coal, the adsorption isotherm for the coal, and the size of the coal particles. Mining operations can affect the particle size distribution and the production of fines and therefore the rate of release. The time the mined coal remains in the mine may also be important in determining total emissions. The methane content of some Utah coals was determined in this study. The methane content of the coals is compared with the chemical and physical properties of the coals and the properties of the seam and neighboring strata. Correlations are developed to better understand the formation and retention of methane by these coal seams. METHANE FORMATION IN COALBEDS Three mechanisms for methane formation may be considered: (1) nonbiogenic formation, (2) formation by anaerobic bacteria during plant material deposition and the early stages of diagenesis, and (3) formation from pyrolysis of coal material during coal maturation. Nonbiogenic formation by thermal processes involving carbon- and hydrogen-containing compounds has been proposed as a mechanism for methane formation in the earth. It is not likely to be of importance where other fossil fuel materials are present. Coal would not survive the temperatures required and hence the methane would need to migrate and be trapped by the coal seam. This mechanism is unlikely for coalbed methane. Formation of methane by anaerobic bacteria undoubtedly occurs during coalification, but the methane may not be trapped until the pore system of the coal is developed, and would likely be displaced by methane formed during further coalification. Methane formed by maturation of the coal material as it progresses from peat to coals of various rank is the most probable mechanism for the formation of coalbed methane. Most of the methane is adsorbed onto the walls of microvoids in coal. It has been estimated that the surface area of one kilogram of coal is between 20,000 m2 to 200,000 m2. Surface area measurements depend on the coal and also on the method of measurement. At 20 atmospheres, in some coals, the adsorbed methane is 10 times greater than methane as a free gas. At 100 atmospheres the adsorbed gas can be as densely packed as a liquid. The volume of methane gas held in coal depends on the volume of gas that exists as a free gas and the adsorbed gas capacity. The volume of free gas in the coal can be calculated from the kinetic theory of gases (methane can be assumed to be an ideal gas because errors would not be greater than 1 % for normal mining pressures). Langmuir (1916) derived an equation for the adsorption of gases on uniform surfaces and this is applied to the adsorption of methane on coal:

Jan 1, 1993

By M. R. Rosen

A technique is presented for simple characterization of the performance of flocculents in various mining applications. The method utilizes three key parameters obtained from raw settling data and combines them into a single athematical parameter called the desirability coefficient. The first two parameters are the timesrequired for the slurry-supernatant interface -to fall to two selected fractions of the starting height, and the third is the clarity of the supernatant liquid. The relative values of the three parameters may be assigned different weights in order to make them correspond with laboratory and field performance requirements of a particular industry. Provision is also made of an, internal comparison of test flocculant data with that of a control.

Jan 1, 1980

By P. C. Cochrane, I. S. Clelland, S. H. E. Phillips

Geological and hydrological conditions in the strata overlying the Salado Formation vary considerably in the Carlsbad, NM, area. The first four shafts sunk at International Minerals and Chemical Corp. (IMC) 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, leading 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 modified to reflect any new or additional information obtained during the progress of the grouting.

Jan 1, 1987