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By S. S. Peng

Since the introduction of shield supports in 1975, safety and production in U.S. longwall faces have improved considerably. Many faces had a daily production of up to 8,000-10,000 tons and productivity reached 600 tons per man-shift. But a longwall face requires expensive equipment which slows down the growth rate of the percentage of longwall production. Among the equipment cost the shield support accounts for 50-60%, a very large proportion. Therefore, it will have a large impact on the growth of longwall mining in the U.S. to reduce the support cost (1).

Jan 1, 1988

By R. M. Hernandez

The Bureau of Land Management (BLM) constructed four passive biochemical reactor systems (BCRs) to treat mining influenced water (MIW) in the Bunker Hill Superfund area near Coeur D?Alene, Idaho between 2002 and 2003. Initially, the BCRs operated very effectively. However, in the past couple of years, the zinc removal effectiveness of the four BLM BCRs has declined [1]. The central objective of this study was to characterize the microbial communities and substrate present within the BLM BCRs and to use these factors to propose strategies to promote sustained sulfate reduction levels. Microbial communities were characterized by quantifying total bacteria and sulfate reducing species. Substrate was characterized by quantifying the percent organic, acid soluble organic, acid insoluble organic, and bioavailable material within the BCR. The results suggest the depletion of bioavailable organic substrates is the primary cause of the decline in zinc removal and not the microbial community structure. The ability to assess the amount of bioavailable organic substrate and microbial community is important to the understanding of the sulfate reducing capacity of the BLM BCRs and developing strategies to facilitate performance enhancement of the current BLM BCRs. The characterization of organic substrate and microbial community structure are also important to improving design of future passive treatment systems for mining influenced waters.

Jan 1, 2010

By Harold L. Lovell

The areas of application, the limitations imposed by water chemistry as well as the advantages and disadvantages in the use of limestone for the treatment of coal mine drainage have recently been described by the authors (1),(2), (3). The process has been demonstrated in continuous, full-scale operation to yield a treated water meeting specifications established by the Pennsylvania Sanitary Water Board and containing excess alkalinity. Their final pH levels are usually less than seven, a condition which avoids consumption of excess neutralization reagents, but which occurs with lime-based processes and results from unwanted side reactions. Operating experience has been cited by Calhoun (4) using ferric waters while others (5), (6), (7), (8), (11), have reported on related research efforts. Despite the advantages including ?the relative simplicity, and minimal costs of the process, there have been very limited industrial applications of mine drainage neutralization with limestone. Although any treatment of these waters may be considered as a temporary control measure (9), the lack of feasible, immediate alternatives, the extensive magnitude. of the waters and the high cost of treatment requires that optimum processes should be utilized and that operating experience in their use be developed as is feasible. This paper will review treatment experience with a ferrous water of moderate pollution loading .

Jan 1, 1972

By Nathaniel White, Todd Kilduff, Justin Laviolette, Dan Laviolette, Randy Zeigler, Sean Sundermann

The Mitchell Point tunnel is a part of several ongoing efforts to connect the 12-mile-long Historic Columbia River trail between Mitchell Point Outlook to Mitchell Point Drive. The tunnel lies inside the Mitchell Spur entablature basalt geologic feature, extending 647 linear feet utilizing a typical horseshoe section with a height of 14.5 feet. The Oregon Department of Transportation (ODOT) required proper vibration control to minimize potential impacts to Interstate 84 and Union Pacific rail immediately below the tunnel excavations and sensitive, rare plants. The method of designing the vibration monitoring program and the results of its implementation show the iterative process of using monitoring to improve blast design as excavation proceeds, such as reducing air overpressure and COVID-related supply chain-constraints.

Dec 1, 2022

By Roy A. Grancher

?The Horn of Plenty seems to have sprung a leak?.? anonymous For the first time in the Nation's peace-time history, shortages have become a way of life for the United States. Such words as scarce, tight, and critical are used in regard to supply, leading to priorities, allocations, and possible rationing as make-shift attempts to satisfy demand. Almost every day a new type of shortage appears in another product area that has traditionally been taken for granted as being in perpetual abundance. The range of coverage extends from basic commodities such as oil, chemicals, cement, steel, copper, cotton, etc., through to machine tools, motors, bearings, electronic components, etc. , to those finished outputs that satisfy our fundamental requirements for food, clothing and shelter. Signs of the times appear in cancelled airline flights, unfilled lines at gasoline stations, no available home freezers, lengthy delays in any furniture deliveries, or to that little old lady seen walking out of a local supermarket clutching her hoard of twenty rolls of toilet paper. What a sad commentary to have to make about our Land of Plenty, so long the envy of the World for its material wealth -- and today with its initials "U. S." seemingly standing for ?Unlimited Shortages.?

Jan 1, 1974

The viability of physico-chemical purification methods such as selective flocculation for separation of two components having similar chemical composition and same crystal structure but different surface properties is demonstrated. Loss of selectivity was observed in a dolomite-dolomite mixture with Polyethylene Oxide (5 million molecular weight) as the flocculant. Hetero-flocculation was minimized using a low molecular weight PEO (MW -105) as the site blocking agent (SBA). Near complete separation was achieved at pH 10.5 at 100% recovery level.

Jan 1, 1993

By P. G. Irwin

Natural resins, those derived from coal and those mined in the Uintah basin, face challenges from synthetic resins that are derived from petroleum sources and rosin or wood sources. In the past, fossil resins from coal were produced by various companies, the last one being Hercules, Inc., which sold BLACKHAWK resin until a fire destroyed the plant in the mid 1970's. Approximately four to fjve million pounds of BLACKHAWK were produced and sold mostly to the printing ink industry. Uintaite, more commonly known as Gilsonite® resin, was widely used by various industries, notably in printing inks, coatings, stains, adhesives, foundry, asphalt paving, and oil well drilling muds. Gilsonite has lost market share over the last thirty years to various synthetic resins particularly hydrocarbon resins that are derived from petroleum sources.

Jan 1, 1990

By George C. Hawley

Historically, mica usage has been low because of limited availability; as a by-product of many small processors, who have lacked motivation for extensive R & D. The discovery of a 30 million ton deposit of 85-90% pure phlogopite, when existing markets are only 300,000 tonnes annually, forced the search for large volume new markets. Increasing costs of energy, petrochemicals, plastics and glass fibers, and environmental constraints on asbestos usage, have led to new opportunities for mica as a reinforcing filler. Extensive research and developments; in beneficiating, processing and treating mica, has been necessary to satisfy these new markets.

Jan 1, 1981

By C. E. Semler

A 5 year test program, involving on-line, in-vessel exposures at Barrick Goldstrike Mines. Inc. has provided valuable information and experience about the materials and designs for brickwork linings in pressure oxidation autoclaves. A variety of brick and mortar products have been evaluated. Properties before and after exposure are used to document the performance. Benefits have included the development of a new silicate mortar improved understanding of brick requirements and increased autoclave operating time between maintenance shut-downs. More improvements are expected in the future based on further information from the test program.

Jan 1, 1997

By D. A. Robbins

The application of remote sensing for environmental measurements is already being utilized. Aircraft mounted imaging spectroscopy has been utilized to evaluate areas of historical mining operations as well as active mine sites. To the extent that remote sensing can provide more sensitive, cost effective, and timely monitoring potential, the technology is of interest to the industry. Questions remain about the application and validation of the data and the availability of the technology in the private sector. This presentation will discuss some of the potential uses, benefits, and concerns related to remote sensing and efforts to monitor the technology's development.

Jan 1, 1999

By W. L. Price

The intelligent selection of wire cloth and perforated plate for screening surfaces seems a rather confusing subject to the newcomer in aggregate processing. The proper application of various screening surfaces is a complicated one and one could consider himself an expert only after many years of working with all applications. However, part of the subject matter could be simplified considerably for, the average screen user. In this paper an attempt will be made to do this, by presenting some comparative specification data along with cost figures Unfortunately, it is impossible in the limited scope of this paper to give actual service comparison records between different cloths or cloth and plate. Anyone who has considered making actual service comparisons for competing screening media is well aware of the almost insurmountable problems Their solution would form the basis for a separate paper on that subject alone. Therefore, this paper will be limited to comparative data up to the point of installation.

Jan 1, 1961

By Halter L. Gould

Since the turn of the century there has been a marked increase in population, industrial and economic growth, and in energy requirements in the United States. During this time our energy needs have been met largely by natural gas and petroleum, but as our reserves of these materials are depleted, we are going to depend more and more on our large reserves of coal. The mining of coal for electrical power production has increased at a rapid rate during the past decade. Over half the coal produced in the United States in 1971 came from mines utilizing surface mining operations (Paone, et al, 1974). Surface mining is expected to increase as the rising cost of oil places more demand on coal for energy. About 57 percent of the coal reserves in the United States lie in the area west of the 100th meridian. About one-quarter of this can be mined by current surface methods. This would involve the disturbance of approximately 1.5 million acres (600,000 hectares). By the year 2000, projections indicate disturbance of about 200,000 acres, or 300 square miles, in the West. Mined areas receiving more than 250 mm of annual precipitation can usually be revegetated without irrigation if the spoils are properly shaped, the surface layer consists of suitable plant growth media, and proven techniques in rehabilitating disturbed rangeland are applied. Areas receiving less than 250 mm of annual rainfall or with high evapotranspiration rates pose a more difficult problem. Revegetation of these areas can probably be accomplished only with major inputs of water and good management (National Academy of Science, 1974).

Jan 1, 1978

By Dan Nilsson

INTRODUCTION A company must have an objective, and that usually is to earn money. In some countries an objective can also be to reduce unemployment in an area or to develop nonindustrialized areas. Government-owned companies can also have as an objective that of serving the com¬munity. This discussion is limited to the consideration of normal companies wanting to earn money. Such an objective, however, has to be defined in more detail. It is not satisfactory only to maximize the total annual profit from, for example, a mining project. In comparison with most other branches, the mining in¬dustry is very capital intensive. When starting a new project, the mining company must invest a lot of money in mines, ore treatment plants, etc. It is normally many years before any income is received from the ore. Fig. 14 illustrates the payments for a new mining proj¬ect with an expected lifetime of 10 years. Whether this project is a profitable one depends on a lot of things. If the company has a shortage of money, it can be impossible to finance the project. Even if the company has enough money, the management may think that perhaps the project may not return the money fast enough. Such limitations will not be discussed here. Suppose that the company has internal funds from its own operation or can borrow them. Since the mining company must invest the money in advance, it is not satisfactory only to add all of the costs during the mine's lifetime and compare them with the total income during the lifetime. The company must include the time value of the capital. In this appendix, the basic investment theory neces¬sary to judge the profitability and costs of mining proj¬ects will be discussed. INVESTMENT THEORY Time Value of Money If a private person has a dollar and puts it into a bank, he or she will receive interest. If the interest rate is r%, the value after one year will be $(1 + r), after 2 years $(I + r)2 , etc. The interest rate represents the time value of money. If the same person wants to have $1 in the bank af¬ter one year, he or she has to put $(1 + r)-1 in the bank today. If the person wants $1 after 2 years, it is neces¬sary to put $(1 + r)-2 into the bank today, etc. So one dollar today is worth more than one dollar tomorrow. It is, of course, not correct to compare money at differ¬ent times since each dollar has a different value. It is necessary to transform all payments to the same point in time. That is called the calculation of the capital value of a cash flow, and to do this an interest rate is used. In the same way, the cash flow from a project like that shown in Fig. 14 can be translated to any other point in time. Most common is to translate all payments to the beginning of the mining period. That capital value is often called the present capital value. Interest Rate What interest rate will the company use? A com¬pany, just like an individual, has the basic alternatives of keeping its money in the bank and receiving interest, or borrowing money from a bank and paying an interest rate. The interest rate represents the time value of money for the company. If the company has a shortage of money, or many good potential investment projects, it has to use a higher interest rate than if it has a lot of money available. Most companies also increase their interest rate as a hedge against the risk involved by using money for uncertain investments, because of taxes, etc. Capital Value When the interest rate has been decided, it is possi¬ble to estimate the capital value of a project. Here the discussion will be limited to the estimation of present capital values. Suppose that one wants to know the present capital value of $1 (Fig. 15), which will be received after n years. To transform it n years back in time, one must multiply it by the factor (1 + r)-, where r is the inter¬est rate the company uses. Table 1 gives these factors for different years and interest rates. Example: At the end of year 5 a mining company has to invest $50 million in a new mine. What is the present capital value at the end of year 0? The company uses an interest rate of 15%a.

Jan 1, 1982

By R. N. Browne

As man searches unexplored horizons for new and economic industry, he must be constantly and acutely aware of the presence or absence of that precious commodity without which Industry, indeed Man himself, could not survive --W ATE R. The water requirements of the world today are magnanimous, considering that in 1960 the estimated consumption in the united States was over 300 billion GPD (1) or more than 1,700 GPD per person (5). The magnitude of the problem can be visualized as one considers that three times this quantity of water will be required in the united States by the year 2 000, when the dependable supplies of water are estimated to be only two-thirds of that required(2). How, then, can we continue to wreak such havoc on that life-sustaining substance -W ATE R? It is necessary, indeed mandatory, that those engaged in the Engineering profession consider it their moral obligation, not only to conserve the quantity of water which their conceived projects may require, but also to treat the effluent in order that the eutro-phication of natural water courses not be abnormally accelerated. The International Nickel Company of Canada Limited consumes some 33-1/2 millions of gallons of fresh water daily at its nine town-sites, fourteen mines and eight plants throughout the Sudbury district of Ontario. The present daily reuse of water exceeds 100 millions of gallons in the same area. It is noteworthy to mention that the milling rate has increased from 46,000 to 70,000 tons per day during the past five years, with no increase in water consumption. In fact, there has been a reduction in fresh water requirements.

Jan 1, 1971

By R. K. Singhal

In 1990, Canada produced 69.4 million tonnes of coal of which some 65 million tonnes was produced by surface mining methods. The two Western Canadian provinces, Alberta and British Columbia produce approximately 55 million tonnes of coal by surface mining. These two provinces also provide the bulk of the metallurgical coal for export. The geological conditions in the Western provinces particularly in the mountain region are complex. The coals are friable and the seams are steeply inclined, sheared, intensely folded and faulted. There may be as many as 15 to 20 coal seams present with true thickness ranging from 2.5m to over 8m. Most of the Canadian surface mines are large (over one million tonnes per annum) using modern mining equipment such as shovels, high capacity trucks and draglines. At present the industry is going through another of its up and down cycles but has continued to make impressive gains in productivity. This has been achieved through greater mechanization, better management practices and a will to succeed in a highly competitive world market. This paper presents an insight into the current status of the Canadian Coal Industry and essentially updates the information given by the authors at previous SME meetings.

Jan 1, 1992

By J. F. T. Agapito

Two flat-lying trona seams 3-to 3.5-m thick, approximately 10 m apart, and at depths of 250 m are mined by room-and-pillar at OCI's Big Island Mine in Wyoming. Continuous miners and a yielding pillar system have contributed to improvements in resource recovery and productivity. Long-term stability with minimal subsidence is needed for a large portion of the mine beneath the Green River channel. This was investigated by computer modeling in 1990. Although results of the study indicated good long-term stability, recommendations were made for stress determinations to verify the model. Stress determinations made in 1997 showed pillar stresses 10% to 20% higher than the model stresses, and barrier pillar stresses 10% to 15% lower. This implies that higher panel stresses will be transmitted from the upper to the lower seam. A stability evaluation of the lower seam is planned before two-seam mining to assess entry widths and support requirements.

Jan 1, 1999

By L. Alagha, O. Molatlhegi, S. Khatibi

"In the present study, the effect of organic/inorganic (hybrid) polyacrylamide polymer on fine coal flotation was investigated. Raw coal samples contain about 37% of ash-forming mineral at a feed size of -75 + 38 um were subjected to flotation tests in the presence of in-house synthesized hybrid Al(OH)3-PAM at different polymer dosages and pH values. Results show a significant improvement in both combustible recovery and ash rejection at 1 ppm polymer dosage. Further improvement of combustible recovery was obtained when flotation was performed at pH 5. Interfacial properties of coal particles before and after flotation were examined through electrokinetic (zeta potential) measurements of coal/water slurries. Zeta potential vs. pH curve were established and compared. In the case of raw coal/water slurry, zeta potential-pH curve resembles the ash-forming minerals (silica and clays) more than coal. After Al(OH)3-PAM-assisted flotation, the zeta potential of froth/water slurry shifted to more positive values point which strongly indicates significant removal of ash-forming minerals from coal by Al(OH)3-PAM. INTRODUCTION Coal has been a major commodity in meeting the world energy demand during the past several decades (Milici et al., 2013). According to the international energy agency, global coal demand will continue to increase for the coming decades. With increasing world population, the global electricity demand would also increase as more people would get access to basic electricity especially in developing countries (Maggio & Cacciola, 2012). Due to this increase in energy consumption, operations in coal mining and beneficiation processes have been highly mechanized to meet the demands. This mechanization has increased the quantity of raw fine coal particles produced which contain high amount of ash-forming mineral matter (slimes). Aplan et al., have reported that the major constituents of ash-forming minerals in U.S.A coal are clay minerals such as kaolinite, montmorillonite and illite (Aplan, 1997). Conventional froth flotation for fine coal cleaning suffers mainly from two major problems: 1) Low recovery of ultrafine coal particles due to slime coating by ash-forming minerals, and 2) The lack of selectivity, which results in the flotation of middlings and entrainment of mineral fines in the froth (Polat et al., 2003). Slime coating on both valuable and air bubbles have been proposed to explain the observed reduction in flotation recovery especially when fine grinding is required. In this case mineral matter may be degraded to extremely fine or colloidal sizes thereby creating difficulty in the water clarification process such as flotation. Slimes inhibit bubble-particle attachment, and increases reagent consumption due to the increase in solid/liquid interfacial area, resulting in low coal recovery."

Jan 1, 2015

By J. Kang

Supercritical fluid extraction (SFE) has became an attractive alternative technology to be a new process to recover metal, of which can be substitute the existing Leaching/Solvent extraction processes. Solvent extraction of metallic ions is a technically important and also well-established process that is used in the chemical and hydrometallurgical industries.1 Solvent extraction techniques use the chelation of metallic ions dissolved in liquid solution with organic ligands. Conventional solvent-extraction technique needs large amount of organic solvents and often creates environmental problems.2 More environment-friendly technology is needed nowadays, and there have been increasing attentions to extract metal ions by SFE. CO2 becomes one of the most notable alternative organic solvents due to its nonflammable, nontoxic, nonpolluting, and relatively inexpensive properties with its moderate critical point (73.8 bar, 31.06 °C). Many works have been reported in metal extraction under the supercritical CO2 (scCO2) solvent.3-5 In this study, to recover cobalt from wastes especially from spent lithium ion battery scrap, we selected two ligands ? Cyanex 272 and DEA (diethylamine) for the metal extraction in scCO2. Cyanex 272 is a commercially available extractant along with its series, Cyanex 301 and Cyanex 302. Smart and coauthors measured the metal extracting abilities of these three extractants, and found that Cyanex 301 and Cyanex 302 extracted metal ions much better than Cyanex 272 in the scCO2 solvent.10 The pH of water contacted with high pressure CO2 (70-200 bar, 25-70 oC) is about 2.8-2.95 based on the calculation and the measurement.6-7 Cyanex 272 is known to be less effective as a metal extractant in this low pH environment compared with other Cyanex series. However, when DEA is added to metal extraction reaction with Cyanex-272, DEA works as a strong base to Cyanex 272 converting Cyanex 272 to a deprotonated form (Figure 1), which results in an easy formation of metal complex and the enhanced extraction rate of metal ion.8 Therefore, the purpose of this paper is the metal extraction from spent lithium ion battery waste using scCO2 with Cyanex 272 and DEA.

Jan 1, 2010

By R. J. Sheets

"INTRODUCTION What is the primary responsibility for geo-engineers in mining? Early in my career, I was asked this question by an experienced engineer. After explaining some various tasks, I was informed that the main responsibility was to monitor. Although this proved true for many cases, I came to understand that monitoring is merely one means to achieve the primary responsibility of a geo-engineer – ensure the safety of all personnel. The potential for groundwater to impact stability allows this responsibility to be shared with hydrogeologists as well. Inherently, we monitor to identify risks; we analyze designs and develop models to mitigate risks; and we are provided opportunities to explain to supervisors the geo-risks to personnel and mine plans that will result from particular courses of action. A couple years ago, I took an opportunity to share experiences from the first several years of my career as a geotechnical engineer with junior geo-engineering staff within my company. The intent was to share situations that were a part of my development, so they could learn and understand their responsibility to the safety of all personnel. Similarly, the purpose of this paper will be to share these thoughts with new geo-engineers in the industry in order to help prepare them for the challenges they will face. WHAT IS OUR PURPOSE? A senior hydrogeologist shared an experience that occurred in their career. The experienced hydrogeologist had spent some time with the hydrogeology staff, most of them relatively new to the mining industry, to understand how they viewed, and carried out, what they perceived as their responsibility at an active mining operation. After a couple months of observing and mentoring, the senior hydrogeologist met with everyone and posed the question above. I am sure that most junior geo-engineers would start explaining different tasks or projects that they must complete. The list would include monitor groundwater levels, track slope movement, evaluate designs, build models, oversee drilling programs, etc. These individuals did as well their supervisor. After going around the room allowing each individual to answer, the experienced hydrogeologist provided them the real answer to the question: SAFETY. If you examine the root intent of nearly every responsibility geotechnical engineers and hydrogeologists have, it is to apply our professional skills to ensure the safety of our workforce. When the objective of safety from the geotechnical and hydrogeology disciplines is achieved, inherently accomplishing the mine plan should follow suit, or it should significantly minimize the impact by gravity or groundwater. The objective of a hydrogeologist is to ensure the soil or rock around an open pit or underground mine is dewatered; this specific objective will reduce pore pressures which could lead to a possible ground failure. They ensure a working bench/UG level is dry, so operations are not dealing with adverse conditions while mining. A geotechnical engineer is expected to use all available information and engineering judgement to provide design recommendations, so that the mine will not catastrophically fail. Additionally, they will implement the monitoring systems to identify hazards in advance in the event that the design is flawed and people need to be evacuated. We all know that safety is important to everyone; however, our particular set of technical skills play a significant role in ensuring the safety of a large portion of the global mining workforce."

Jan 1, 2018

By F. J. Murrell

No other region of the world is enjoying the tremendous growth of power use that is currently being experienced in Asia. Fortunately for those of us in the coal industry -particularly in Asia -the preponderance of the power plants being planned or under construction designed to use coal as the power plant fuel. This has produced a significant increase in the demand for steam coal, which has in turn encouraged many of us in the industry to develop new coal mines. One country that has enjoyed very substantial growth in coal production is Indonesia. This developing country of 195,000,000 people who live on the nearly 13,000 islands of Indonesia have emerged very quickly to become the third largest exporter of steam coal, following only Australia and South Africa. Almost all coal in Indonesia is mined by surface mining methods. This paper will examine the surface mining of coal in Indonesia, as it continues to be an important part of the supply equation for coal in Asia.

Jan 1, 1996