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By R. N. Chakravorty, R. J. Kolada

Explosions of methane in coal silos and coal ships is an ever present hazard. Recent investigations have shown beyond question that considerable accumulations of methane do occur in coal storage silos and numerous recent explosions in coal transport shipping strongly indicates that the same conditions also exist in ship storage holds. Investigations have shown that the main concentrations of methane occur within the actual coal pile. Within this region normal silo and ship ventilation systems are ineffective. The main 1ine of defence is therefore to exclude potential sources of ignition or to place the coal in an inert atmosphere, or both. This paper presents the results of a methane survey of all operating silos in Western Canada. These results demonstrate that a serious and widespread hazard of explosion exists. This paper also discusses various methods by which this hazard may be reduced including methods of venti1ation, inertization, microbiological control and early warning systems.

Jan 1, 1987

By Jock McGregor, Deepak Malhotra, Leonard Harris

After more than 100 years, alkaline cyanide leaching of gold and silver ores, either directly in the case of oxidized ores, or after pretreatment of refractory ores by roasting, pres­sure leaching or bacterial leaching, remains the dominant r leaching method to extract the precious metals f om ores. Leaching with halides (chlorine, bromine and iodine) and with thiourea and thiosulfates is less common but prac­ticed in some cases to dissolve the precious metals both from ores and jewelry and electronic scrap. Cyanide solutions can contain from 1 ppm Au to 30,000 ppm Au. According to the source, i.e., agitated tank leach­ing, heap leaching, eluates from stripping activated carbon or waste electroplating solutions. Similar variations occur with silver which can have a profound influence on the recovery method. The presence of other elements in the leach solu­tions, particularly mercury and copper, likewise play an important role in the procedures required to recover the gold r and silver values f om solution. The same circumstances are found when lixivants other than cyanide are used to dissolve the precious metals. For decades, the preferred method of recovering gold and silver values from alkaline cyanide leach solutions was by zinc dust precipitation according to the Merrill Crowe process developed in the late 19th century. Finely ground gold and silver ores or concentrates were either leached directly or after roasting, in agitated tanks or Pachucas and subjected to solid/liquid separation by filtering or by treat­ment in counter-current-decantation washing thickeners (CCD). This solid/liquid separation step was often very dif­ficult especially when ores containing high quantities of clay were treated which caused filtration or thickening problems. Following testing and development by the U.S. Bureau of Mines (USBM) in the late 60s, the introduction of carbon­in-leach (CIL) or carbon-in-pulp (CIP) plants to recover gold and silver from leach pulps was one of the greatest opera­tional and cost saving improvements made in the industry in South Dakota and quickly spread around the world to be the most common process to recover gold and silver from cyanide solutions.

Jan 1, 2000

By M. J. Zdunczyk

Located approximately 50 miles northeast of Knoxville, Tennessee, Short Mountain Silica mines the Clinch Formation, an orthoquarzite, for silica sand. In 1980, a Knoxville resident and area contractor visualized mining Short Mountain for silica sand. Because APG Industries, the main market for the glass sand product, was only 48 kilometers from the site, many silica sand companies became interested in the property. In 1986, J.D. Nicewonder began to develop the site, and in May of 1988, APG Industries received the first sand shipment.

Jan 1, 1992

By Robin J. Batterham, Dave J. Robinson

The most significant trend in flotation has been the ever-increasing scale of operations. There is, however, doubt that this ongoing trend is enough to maintain the economics against trends such as falling grades, increasing mining costs, pressure on water supply and demand, rising energy demands needed for mineral processing, and a focus on whole of life value and mine legacy issues. We comment on the ramifications of broader uptake of more sustainable mining for mineral processing methods and address the specific question of whether recent progress in in-place recovery will lead to a timely breakthrough. The answer proposed is that this is possible in the next 10 to 20 years, but in the meantime the focus is just as likely to be on removal of waste (beneficiation) much earlier in circuits. Either way, mineral processing and flotation as we know it will change significantly. 

By Nellie E. Guernsey, Louis J. Sousa, Alfred Weiss, Nickolas J. Themelis

Over the past decade, numerous factors have led US copper firms to face increasingly severe competition from low cost foreign producers. As a result, greater attention is being devoted to developing and implementing new technology that can reduce costs and maintain the competitive position of domestic firms while simultaneously meeting environmental requirements. To obtain a better understanding of the likelihood of the development, adoption, and use of innovative copper technologies in the future, the Bureau of Mines contracted with Mineral Systems Inc. of Stamford, CT, to undertake a systematic survey of technological experts in industry, government, and the academic community. According to the survey, major developments in exploration over the next 25 years are likely to be in technologies that facilitate analysis and interpretation of deposit data rather than those that enable the collection of additional data. Most new copper mining and beneficiation technologies are likely to represent evolutionary extensions of existing systems with a notable increase expected in the application of information systems technologies and computer control methods. A possible movement towards increased usage of continuous mining systems in copper was also noted. Experts indicated that several copper smelters are under consideration for extensive renovation and, as a result, flash smelting technology is expected to become much more widely used in the US. A gradual movement toward continuous smelting methods was also forecast. In copper refining, the major technological change expected is the gradual automation of various refinery operations. Finally, though increased usage is expected, in situ solution mining and hydrometallurgical processing of sulfide ores are not expected to become widespread over the forecast time horizon. This first article in a two-part series describes the survey method chosen and the technological innovations selected for eval¬uation. Also discussed are the assessment panels, background scenarios, critical events, and diffusion forecasts. Next month, part two will address technology forecasts resulting from the study. Featured are discussions on future copper exploration, mining, beneficiation, smelting, refining, and recycling. A cost/benefit analysis will also be included. Methodology Selection of Assessment Method To develop a consensus forecast of technological change in the copper industry, a technique for systematically polling subjective opinions of experts was required. After conducting a literature survey and some preliminary testing, the direct probability assessment method was selected. With this assessment method experts are asked to express in quantitative terms their judgment of the probability that a specified event will occur, usually over a series of time frames. The method was chosen because the experts were observed to be more comfortable with this approach during the testing period, and the results of this process effectively satisfied the assessment objective. The experts generally could provide more precise estimates of the timing of future events using this technique because it was the least cumbersome of the assessment methods tested. Identification, Selection, and Description of the Technologies The initial list (Table 1) of innovative copper technologies assessed in the study was developed from two principal sources: knowledge and expertise of the study team and a review of relevant technical literature. From this list of 47 potential technologies, 10 were selected for detailed assessment. Table 2 lists 35 technologies that were subsequently identified in the first series of assessments. Twelve technologies from this list were also selected for detailed evaluation in a second assessment round. Criteria used for the final selection of technologies for detailed assessment specified that: • The expected impact of each technology on copper supply (i.e.,

Jan 9, 1983

In a future world of 8.5 billion people in 2035, the Energy Information Administration's (EIA) projected 50% increase in energy consumption will require true "all of the above" energy resource use from oil, gas, renewables, nuclear, and coal. In particular, coal will continue to be the world's energy cornerstone, providing more incremental energy over that same time period than any other single fuel. Coal has long been a centerpiece of a low-cost, high-reliability electricity grid. Today there are 1.3 billion people across the globe without access to electricity and 2.7 billion people who do not have clean cooking facilities. The problem is spread across the developing world, but it is particularly severe in sub-Saharan Africa and developing Asia, which together account for 95% of people in energy poverty. Without a commitment to achieve universal energy access it has been estimated that by 2030, there will be an additional 1.5 million premature deaths per year caused by household pollution from burning wood and dung and through a lack of access to clean water, basic sanitation and healthcare. Modern energy sources are essential to meeting these challenges.

Jan 1, 2012

By L. Yan, T. Lutz, J. Noll

"Mine disasters, such as fires and explosions, can create a hazardous atmosphere due to the generation of carbon monoxide (CO). After a mine disaster, contaminated mine air can enter the refuge alternative (RA) as miners enter. Most built-in-place (BIP) RAs use an air delivery system to provide an unlimited supply of breathable air through a borehole which also serves to purge contaminants. In order to determine what levels of contaminants enter the RA, researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted testing in NIOSH’s Pittsburgh Experimental Mine using groups of 5, 15, and 30 subjects entering the RA. The experiment used sulfur hexafluoride (SF6) as a tracer gas that was released into the air outside of the BIP RA to establish a uniform concentration. After the human subjects entered the BIP RA, the SF6 levels inside the RA were measured to quantify how much of the tracer gas entered the BIP RA. In tests conducted while the borehole air supply was left off as test subjects entered, interior contaminant levels were less than 3% of the exterior concentration. In tests conducted with the borehole air supply activated as test subjects entered, the interior contaminant levels were measured at less than 2% of the exterior concentration. Considering a mine disaster can result in 10,000 ppm of CO in the mine atmosphere, these percentages indicate that unhealthy CO concentrations that may lead to headaches, dizziness, and loss of judgement can occur in a BIP RA. This information will help mines make decisions concerning air locks, air delivery systems and a determination if purging mechanisms are necessary. INTRODUCTION The Mine Improvement and New Emergency Response Act of 2006 (MINER Act) was enacted in the wake of three mine explosions/fires that claimed 19 lives that year. Intended to help improve underground coal mine accident preparedness, the MINER Act includes provisions that target mine safety issues in areas such as emergency response planning, adoption of new technology, training and education, and enforcement of mine safety standards (MSHA, 2006). Section 13 of the MINER Act specifically directs the National Institute for Occupational Safety and Health (NIOSH) to provide for research into the effectiveness and viability of RAs for underground coal mines. This mandate culminated in the 2009 adoption of changes to the 30 CFR mining health and safety regulations, requiring underground coal mines to provide RAs capable of maintaining a life-sustaining environment for persons trapped underground. Such RAs can be either pre-fabricated or BIP shelters. The regulatory changes also include provisions establishing requirements for Mine Safety and Health Administration (MSHA) approval of RAs and their components, and among these provisions are numerous criteria for providing a safe, breathable atmosphere within RAs."

Jan 1, 2018

By A. K. Basu

Rapid industrial growth in India has caused the country to realize the strategic importance of its zinc and lead deposits. Private companies, nationalized in 1965, are now a corporate public sector organization that is making great strides in developing the nation's lead-zinc mining capability. The main mining area is centered around Zawar at Rajasthan. It consists a group of mines - Mochia, Balaria, Zawarmala and Baroi. Mining activities have also been extended by opening the mines at Rajpura-Dariba at Rajasthan, Sargipallie at Orissa and Agnigundala at Andhra Pradesh. A huge deposit has been explored at Agucha in the Bhilwara district but full-scale production has not yet begun. Annual consumption of zinc and lead in India has risen steadily from 25 and 7.9 kt (27,500 and 8700 st), respectively, in 1973-1974 to 162.8 and 80 kt (179,450 and 88,000 st), respectively, in 1989-1990. Mine production has also risen consistently to cope with the increased metal demand. The mining company hopes to increase production at existing mines and upgrade the beneficiation and smelting facilities. Moreover, mining operations may be expanded by opening up new units that are now awaiting governmental clearances. Technology status Mining technology has undergone a rapid, large-scale transformation, with an accelerated pace of new, larger capacity mine development. Notable advances include the introduction of mechanized ore extraction methods and

Jan 1, 1991

By Ian Mitchell, Peter Faganl, Paul Haddad, Rob Dunne

During the gold cyanidation process, cyanide can be lost from the leachate by various chemical routes. The products of these cyanide losses include base metal cyanide complexes, thio­cyanate and cyanate. These losses are particularly important when treating pyritic or cupriferous ores since the two most sig­nificant cyanic ides, in order of importance, are sulfides and cop­per bearing minerals (I). Cyanidation of pyritic minerals results in the formation of thiocyanate. The problems caused by cyanide soluble copper minerals are well known to the gold processing industry and have been reviewed by several authors (e.g. 2, 3). An important consider­ation, especially with a number of more recent leaching tech­nologies, is the effect of the CN :Cu mole ratio, R, on the gold leaching kinetics. In order to efficiently leach cupriferous ores, it is important that R is maintained at a level that allows suffi­ciently rapid leaching without excessive use of cyanide. The optimum value for R in a fixed leaching system would appear to lie between 3 and 4. This is based on the early observations that the leaching rate is very slow when R is below 3, with a rapid increase in the leaching rate above 3 (2, 3,4). The leaching rate increases gradually when R is greater than 4 (4). The major Cu(I)-cyanide complex in this range of R values is the [Cu(CN)J]2· species. It has been postulated that leaching occurs due to either uncomplexed cyanide or the fourth ligand in [Cu(CN)4]3·, since the stepwise formation constant for this complex is very small (2, 3). An additional consideration when leaching cupriferous ores is the oxidation of cyanide by Cu(II) minerals, resulting in the formation of cyanate. It has also been reported that both sulfide minerals (5) and activated carbon (6, 7) catalyse the oxidation of cyanide to cyanate. From the above discussion, it is important for the leaching con­ditions to be carefully controlled when treating pyritic and cuprifer­ous ores in order to achieve efficient and economically viable leach­ing. For example, large concentrations of thiocyanate in the leachate would reveal large cyanide losses and thus indicate the need for a pretreatment step to oxidize the sulfides. Alternatively, a low R value would indicate slow leaching kinetics and consequent low gold recoveries, indicating the need for increased cyanide dosage.

Jan 1, 1996

By Alwyn Protheroe, Steve Smith, Herbert Jr. Gibson

In September of 2000, Cowin and Company, Inc., contracted with Paramont Coal Corporation to construct a large decline approximately 820 m (2,700 feet) in overall length at a grade of 8 degrees to the Lower Banner Coal Seam. This paper will discuss the methods used by the contractor and owner to overcome the unique problems required to construct this tunnel in a coal mine environment. The problems include, initial design considerations, equipment selection, ventilation, ground control, control of water in?ows, and placement of concrete.

Jan 1, 2003

By G. Granger, D. Malhotra

The paper briefly reviews the criteria employed in the selection of chemical reagents for testing and discusses the steps involved in laboratory and plant evaluation of these reagents. An example of successful implementation of reagent change in the plant is illustrated.

Jan 1, 1986

By J G. Dunn, S M. Thurgate, A C. Chamberlain, P Franzmann, M Jeffrey, L J. Warren, G E. Poinen, T Williams

Gold has always fascinated mankind. From Tutankhamen's mask to the huge nuggets that have been found in the Australian outback, gold has quickened the pulse and fevered the eye. But in recent years, governments around the western world have shown a singular lack of interest in research into gold processing, with many programs being cut. There are some notable exceptions, fortunately, and this paper summarizes a large research effort that is well supported by the Australian government and the Australian gold industry. The AJ Parker Cooperative Research Centre for Hydrometallurgy is an unincorporated joint venture between the CSIRO Division of Minerals, Murdoch University, Curtin University of Technology and the Western Australian Department of Minerals and Energy. The Australian Mineral Industry Research Association (AMIRA) is the Parker Centre's broker for generic R&D contracts with industry. Each of the partners makes available staff, students and equipment to further the work of the Parker Centre, and the Australian Government provides additional funding. The Parker Centre is nearly five years old and has grown spectacularly in that time. There are now about 30 full-time-equivalents of effort from 50 scientists and engineers, as well as about 40 postgraduate and honours students. The fundamentals of the key operations in hydrometallurgy are studied in three programs: leaching (which includes pretreatment by roasting etc), precipitation (or crystallisation), and surface processes (which includes solid/liquid separation, adsorption, solvent extraction, etc). A large part of the Parker Centre's R&D is directed towards gold processing technology. In Australia, a dramatic increase in gold production, from about 30 to nearly 300 tonnes per year (1977-1997), has been made possible largely as a result of a brilliant metallurgical innovation, the carbon-in-pulp process. However, falling head grades eg 2.56 to 1.84 g(Au)/t over the last 10 years, and environmental concerns, are squeezing profit margins. There is increasing pressure to reduce costs, and the Parker Centre program is focussed on providing the scientific understanding required to do this. A selection of research highlights will be given, to indicate the depth and breadth of the R&D at the Parker Centre.

Jan 1, 1997

By Glenn P. Jones

Laterization of syenite and other rocks in north Alabama produced material which was picked up and carried by streams to southeast Alabama. These streams deposited the aluminum rich material in the sinkholes of a karst topography developed on the Clayton Limestone. Measurement of the bearing of the long axis of each deposit in the Screamer area, along with plotting the location of these deposits on a map, indicate a depositional pattern controlled by local fractures or solution zones in the Clayton Limestone. The sinkholes and channels dictated the original structure of the deposits. Additional structure changes have resulted since compaction of the deposits by continued solution of the underlying limestone. The original material in these deposits was enriched by the removal of silica to form bausite and bauxitic kaolin during deposition and compaction. Subsequent ground water action has reintroduced silica into the deposit leaving a core of bauxite.

Jan 1, 1972

The US Bureau of Mines' dictionary of mining terms defines productivity as "the efficiency with which economic resources (men, material, and machines) are employed to produce goods and services." Or, the relationship between the physical outputs and the physical inputs used to produce those outputs. As demand for mine materials dropped, mining companies and equipment manufacturers discovered that ratios between the inputs and the final products were disproportionate to the profits realized. Some companies are fighting for survival. The US, while still the most productive country in the world in absolute terms, is looking over its shoulder as other industrialized nations continue to exceed its yearly productive growth rate. According to John Belcher, Jr., of the American Productivity Center in Houston, TX, the US has seen a steady decrease in productivity growth since the mid-1960s. During the post World War II period, the US labor productivity growth rate was 3.2% annually. The slowdown began in 1965 and by the mid-1970s, the country's annual growth rate was 1%. By 1978, labor productivity growth ceased to gain at all and from 1978 to 1980 a 2% decline occurred. Solutions to the productivity decrease are increasing product prices or improving productivity. By increasing prices, though, the producer runs the risk of pricing himself out of the competitive market. To maintain an acceptable profit level, prices must increase proportionately higher than required to offset production cost increases, Belcher says. Many companies are turning to in-house productivity improvement programs as an answer to increased costs and declining profits. These programs are geared toward management commitment and employee awareness of what productivity means. Companies are finding ways of measuring productivity levels in financial reporting, budgeting, and planning. Organizational teams have been formed to coordinate activities and oversee product management, and improve productivity of materials and capital investments. This special issue of Mining Engineering examines productivity in the mining industry. First, there are articles about various, and different, factors that affect productivity in each of ME's five main readership areas - exploration, mining, processing, coal, and industrial minerals. There is also a look at mining industry productivity from the manufacturer's view. The next section of this special issue is devoted to some topics that affect all areas and sectors of mining: research, management practices, computers, maintenance, and energy management. Then follows case studies in exploration, coal, and iron and steel. These studies provide examples of practices and strategies used by companies and operations to boost productivity.

Jan 11, 1983

By Hugh R. Wilson

Echo Bay's Waste Management Program for its Lupin Mine was developed in response to the terms and conditions of the water license issued to the mine in 1981 by the Northwest Territories Water Board. The gold mine, located about 80 km (50 miles) south of the Arctic Circle, commenced production in 1982. The Waste Management Program was based originally on the total containment concept, contingent on future treatability testwork results indicating the best treatment method to ensure pond discharges would be in compliance with stated Northwest Territories Water Board discharge criteria. To assess the various treatment technologies, an investigative program was established to determine the most effective means for treating the tailings pond water. In the course of milling, about 850,000 m3 (11 million cu yd) of tailings are produced annually that require appropriate management to protect the environment. This annual tailings stream consists of about 175,000 m3 (229,000 cu yd) of solids and 675,000 m3 (883,500 cu yd) of water. Following the completion of the required waste management studies, a two-ponds-in-series concept of tailings impoundment was developed. To attain this concept, the tailings impoundment area would require modification and construction to enable the use of such a system.

Jan 1, 1991

By K. Ohga, V. J. Hucka

The presence of methane gas in mines creates hazards of explosions, fire and suffocation. Under certain conditions the occurrence of methane also poses a danger of gas and coal outbursts. Consequently, prevention of gas and coal outbursts in coal mines requires a sound knowledge of methane gas occurrence in mine workings. However, the direct method of determining methane content of coals developed by the U.S. Bureau of Mines is time and labor consuming for measurement, a new transportable methane tester was developed for Japanese coal mines. The instrument automatically measures emission gas from coal samples in the underground and also records and stores the data. Back on the surface, the tester can be connected via a RS 232 port to a PC computer for methane content estimation. Details of this technique are described here. Results on methane content determined in Japanese and U.S. western coal seams are discussed, as well.

Jan 1, 1991

By Gabriel Babut, Ion Matei, Roland Moraru

Several controlled recirculation systems are in operation wor1dwide. As an unconventional technique of ventilation the implementation of such a system requires particular safety conditions and a well-founded set of feasibility factors and parameters. On the other hand, many mines in Romania are facing problemms in meeting the growing ventilation demands, so that controlled air recirculation could give an answer. The present paper presents the results of the work in this field, based on a detailed theoretical approach. Parameters wich must to be taken into account were identified and analysed, numerical simulation are carried out and an experimental test-scale model is presented.

Jan 1, 1997

By Walter G. Steblez

The countries of Eastern Europe are former members of the Council for Mutual Economic Assistance (CMEA). Geographically, they are located in Central Europe (Poland, Hungary, Czechoslovakia) and Southeastern Europe, largely in the Balkans (Yugoslavia*, Bulgaria, Romania and Albania*). It is important to remember that all of the countries of Eastern Europe had central planning imposed on them by the Soviet Union during the years following World War II. "Stalinist" policy for industrial development had three important tenets: • central economic planning, or a nonmarket-based command economy with administratively set prices; • economic priorities that stressed the development of heavy industries such as mining, metallurgy (steel) and heavy machine building; and • self-sufficiency at all costs, which was aimed at abolishing reliance on the world capitalist market, or reducing it to a minimum. Essentially, the system of industrialization that was used in the Soviet Union in the 1930s and 1940s was imposed on Eastern Europe. Organic market economic development in Eastern Europe ceased during this period. The flaws of this experiment became apparent when mineral processing facilities were set up in many areas of Eastern Europe that did not have reliable resources. Poland, Hungary and Romania are good examples of this situation. The Soviet Union became the principal supplier of iron ore and other minerals and mineral fuels, not only to these countries but to the Bloc as a whole.

Jan 1, 1992

By Craig Cina

Transporting goods from producers to consumers is a fundamental part of the US economy. The demand for transportation closely reflects the economic health and well-being of the nation's industrial, commercial, and agricultural sectors. The inland waterway barge industry has traditionally played a key role in transporting needed commodities to industries on an economical basis. Barges account for 10% of the domestic intercity tonnage carried by all transportation modes. Water carriers operating on inland waterways hauled more than 450 Mt (500 million st) of cargo in 1980-up from 428 Mt (472 million st) in 1970. Inland Waterway Shipments Metallic and nonmetallic minerals comprise one of the largest commodity groups moved on inland waterways. As illustrated in Table 1, metallic and nonmetallic mineral shipments accounted for more than 69 Mt (77 million st), or nearly 15% of all commodities shipped in 1980. Putting this tonnage in perspective, coal and petroleum represent the two largest commodities moved on inland waterways. In 1980, petroleum and petroleum products accounted for 138 Mt (152 million st), or 28% of all commodities shipped. Similarly, coal represented 120 Mt (132 million st), or 25% or all commodities shipped. Even though shipments of metallic and nonmetallic minerals are smaller than coal and petroleum, they still account for a sizeable portion transported. The inland barge industry moves a variety of metallic and nonmetallic minerals ranging from manganese ores to building cement. Minerals transported by barge include: • iron, copper, bauxite, and manganese ores for metal production; • lime and limestone for construction and electric utility scrubbers; • phosphate rock, natural fertilizers, and gypsum for agricultural needs; • sand, gravel and crushed rock, clay, asphalt, tar, and pitches, and building cement for construction purposes; and • a host of other minerals to meet industrial needs. A few mineral commodities are responsible for a large proportion of waterborne mineral shipments.

Jan 10, 1982

By Liuhuai Ding

Background of Ocean Mining Research Inspired by the 1970?s deep seabed mining activities of other nations, China started ocean mining research work within the framework of the International Law of the Sea Treaty (UNCLOS) and the subsequent establishment of the International Seabed Authority in the 1990?s. This work has been carried out mainly with the cooperation of the Changsha Research Institute of Mining And Metallurgy. We have been committed to this work to fulfill our responsibilities and obligations as a Pioneer investor under UNCLOS and also to support the much needed development of deep-sea technology in China. Exciting recent advances by Nautilus Minerals in the development of seafloor massive sulfide deposit exploitation has led us to a new perspective of ocean mining and some re-evaluation of ocean mining economics. This has provided us with an opportunity to support more efforts in ocean mining research. We will not delay the development of our ocean mining system and corresponding technology, although commercial mining in the deep-sea area may not occur for many years.

Jan 1, 2008