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By R. Srikanth

Dust control in high production longwalls is a major problem requiring, among other things, careful attention to the design of operating practices, and ventilation schemes. Several studies have shown that the shearer is the major source of dust on a longwall face. Support movement has not been regarded as a major source of dust in U.S. longwalls; yet under certain conditions, 31 percent of the shearer operator's dust exposure can be due to support movement. Several methods have been developed for the control of shield-generated dust. Yet the need for better methods is apparent. In this paper, the amount of airborne respirable dust generated per shield move is estimated from specially designed experiments on longwall faces. A total of ten experiments were conducted in five longwall faces in four different mines. Each experiment involved one face visit and lasted three to six hours. The contribution of shield movement to the airborne respirable dust concentration immediately downwind of the shield moved, varied between 0.12 and 1. 75 mg/m3 in the five longwall faces. The mass of airborne respirable dust generated by shield movement was found to vary between 39 and 386 milligrams per shield move. The results from this study reveal that control of dust from longwall shields requires a combination of approaches involving alternative operating practices, reducing shield dust generation rate, increasing face air flow, and decreasing personnel exposure.

Jan 1, 1994

"How Wall Street Darling Molycorp Undermined the U.S. Economy, Degraded our National Security and Distorted the Global Economic Balance and How These Falsehoods Continue to be Promoted Even Today INTRODUCTION & SUMMARY In 2007 the Molycorp Mountain Pass rare earth mine was resurrected from its desert-grave in California by its then-owner Chevron Mining. Responding to elevated rare earth prices Chevron began processing on-site rare earth concentrates left over from past mining operations that were terminated in 1998i. Chinese demand had sparked what was being described as a commodities super-cycleii. Commodity prices were on the move. Wall Street smelled opportunity. In 2008 Goldman Sachs, Pegasus Partners, Resource Capital Funds, Traxys North America LLC and Carint Group LLC acquired the mining assets from Chevron. In an environment of ever-declining ethical standards and regulatory consequences the private capital group and their investment bankers would bring Molycorp to market. Molycorp, with its high powered investment banking team of Morgan Stanley and J.P. Morganiii, easily dominated the contest. Molycorp promoted itself, largely based on its past operating history and proven reserves, as the best company to challenge China’s monopoly control over the production of rare earths: a group of elements critical to most advanced technologies and U.S. defense systemsiv. Most of Wall Street’s hottest investment sectors were dependent on these materials: alternative energy, green technologies, computing, personal communications, advanced electronics and defense systems. By late 2010 there were dozens of prospective rare earth start-up ‘mining companies’ seeking capital. Eventually the number of prospective rare earth mining companies seeking capital exceeded 400, despite the reality that supply requirements of this market were disproportionally small when compared to other natural resource sectorsv. In the world of finance ‘smart money’ picks the winners. Consequently just twovi projects attracted nearly all of the capital (Molycorp and Lynas). Wall street picked Molycorpvii. This paper will primarily focus on Molycorp. By early 2010 the words “Molycorp” and “Rare Earths” electrified many people in the mining industry, most non-Chinese manufacturing technology companies, U.S. & allied defense contractors, technocrats in the U.S. national security community and eager investors across most of the world’s stock markets. It was the hottest story of the yearviii. The financial, technology and defense press coverage verged on euphoric: heaping fuel on fuel until the highly combustible Molycorp-pyre cast a long shadow over all of its rivalsix. When the IPO match was lit the spectacular flaming pyre sucked all of the oxygen out of the rare earth spacex. Molycorp was ranked the most lucrative IPO of 2010, resulting in record breaking profits to its private investors and massive returns for its early stock holding investors."

Jan 1, 2017

By B. Radwanek-Bak

The assurance of future raw materials supply to the EU mineral industry has become, in recent years, one of the most important tasks of the EU Commission. It is focused on creation a new mineral policy within the EU zone. One of the starting points for this activity was identification of the mineral commodities that are critical for the sustainable development and technological progress. The paper presents the glance to this problem from the National Member level. Domestic mineral reserve base as a possible source of critical raw materials for the EU was shown. Poland cannot be considered as its resource base. The source of these raw materials are not only scarce in Poland, but also they are not produced, and their demand is now - and according to forecasts is going to be in the future - met by imports. The raw materials in question are not considered exactly critical for Polish economy, but they are of limited economic importance. On the other hand, their growth is a best opportunity and at once the need to the future sustainable development.

Jan 1, 2011

By Xianyang Qiu, Xiuzhi Shi, Chen Xie, Xiaofeng Huo, Yanhai Wang

In upwards medium-deep hole cut blasting, many confinement effects exist due to the small number of free surfaces, which is mainly provided by an empty hole. If the cut blasting effect cannot meet expectations, then subsequent blasting construction will be seriously affected, and large security risks to operators in the stope can be induced. The number of free surfaces is directly related to the layout of the cutting borehole. Therefore, it is necessary to optimize the layout of the first round of cutting boreholes. Theoretical analysis, numerical simulations, and field tests were used to study the formation process of cut blasting and optimize the layout of the first round of cutting boreholes. Based on the blasting parameters in the field, LSDYNA software was used to establish cut blasting models with four kinds of borehole layouts in the first round. The RHT constitutive model was used to simulate the rock-breaking effect. The numerical results show that the cut blasting effect is optimal when Nos. 3, 5, 7, and 9 are charge holes and Nos. 1, 2, 4, 6, and 8 are empty holes. In addition, the greater the number of empty holes, the larger the release space and the better the cut blasting effect. The uniformity of the empty hole distribution, namely, the uniformity of the release space, also affects the cut blasting effect. The field results indicate that a good cut blasting effect can be achieved by optimizing the borehole layout.

Sep 7, 2023

By Georgene Renner, William R. Yernberg, Steve Kral

Allmand exhibited its LSC 100Light Sequence Commander, the mining industry’s first automatic lighting and command control system. The system is available with all of Allmand’s portable light towers. The LSC100 uses a preset photocell sensor that allows the light tower to be automatically turned on or off. At dusk, the sensor engages the power unit and then activates the light. At dawn, the sensor automatically shuts off the light. The unit also features an eight-event digital timer that allows eight separate sequences daily. The LSC100’s sequenced light control ensures that the engine is started before the lights are turned on or off. This prevents possible generator damage that can occur if the unit is powered down under load. Also, a low-fuel shutdown sequence helps protect the generator from damage by automatically shutting down the unit when the fuel level reaches 10 percent. And the LSC100’s smart circuitry senses engine water temperature during startup, determines the glow-plug time requirement and schedules repeat intervals, if necessary, to start the diesel engine.

Jan 1, 2004

By Russell Miller, Fun-Den Wang

High Pressure Water Jet Assisted Tunneling The high pressure water jet assisted tunneling project was conducted in a granite quarry near Skykomish, Washington, approximately 90 miles east of Seattle. A 7-ft diam tunnel boring machine was modified and equipped with high pressure water jets. The concept that tunneling rates can be improved by using high pressure water jets was validated, with an average increased advance rate of 50% to 60%. For some tests, the advance rate was more than doubled. A comprehensive economic analysis has shown that very significant savings are possible. At a 50% increase in advance rate, cost savings of 14% and 24% were projected for 10-ft and 20-ft diam tunnels respectively. These benefits were seen to be relatively insensitive to water jet equipment costs.

Jan 1, 1976

By F. Schreiter

The Ore Mountains in Germany have a history of more than 850 years of underground mining activity. This has created a situation where thousands of old mine shafts and adits are due for rehabilitation. While no long-term stable rehabilitation was executed in previous centuries, those abandoned mine sites which date back to the uranium mining boom from 1945 to 1962 were rehabilitated immediately after mine closure according to state-of-the art technology. Over the years, however, it has become obvious that most of these sites are not long-term stable and thus it has become necessary to rehabilitate them a second time. Technical University Bergakademie Freiberg is carrying out a research project on the optimization of this process. 70 mine site rehabilitation projects, the technology and the materials used have been assessed. A technical guideline for future rehabilitation projects, based on the outcomes of this assessment, is under development with the goal to make it easier, faster and more economical to select and apply suitable designs and construction materials for dams, plugs and other rehabilitation structures in former uranium mines.

Feb 27, 2013

By F. Freme

Coal production in the United States reached a record level in 2005, ending the year at 1.03 Gt (1,133.3 million st) according to preliminary data from the U.S. Energy Information Administration (Table 1). Production in 2005 was 19.2 Mt (21.2 million st) higher than the 2004 level of 1 Gt (1,112.1 million st) and surpassed the prior record set in 2001 by 5.1 Mt (5.6 million st). Although total U.S. coal consumption rose in 2005, not all coal-consuming sectors had increased consumption for the year. Coal consumption increased in the electric power sector by 2.2 percent and declined in the other industrial sector, while coking coal consumption decreased slightly.

Jan 1, 2006

By Alphonce Wikedzi, Mussa D. Budeba, Samwel V. Manyele, Sospeter P. Maganga

The present study provides an overview of the challenges and opportunities in processing complex gold-copper ores. The systematic literature review was conducted using Scopus database and seven-step methodological approach. The study indicates that the major challenges in processing complex gold-copper ores through the conventional cyanidation method include (1) increase in cyanide consumption; (2) increase in cyanide destruction cost; (3) low gold recovery; (4) decrease in adsorption efficiency; (5) decrease in electrowinning efficiency, and (6) difficulties in the measurement of free cyanide concentration in the leaching system. Moreover, the study indicates that several methods have been developed and some have been implemented in the mining industry for processing complex gold-copper ores. This includes ore segregation, pre-aeration, pre-treatment methods (e.g., ammonia), alternative lixiviants (e.g., thiosulfate, thiocyanate, glycine), cyanide destruction methods, and cyanide and copper recovery technologies. The study concluded that using lixiviant mixtures (e.g., cyanide-glycine), pre-treatment with environmentally friendly reagents (e.g., glycine) and the integrated membrane-based process (SuCy process) are new directions in processing complex gold-copper ores. However, more investigations are required to advance these processes to a commercial scale.

Sep 30, 2023

By D. Sohn

Work accidents have an essential impact on the economy of a country and in final consequence on each company. The main purpose of industrial OHS is to maintain and promote the health of all employees. Healthy working conditions increase efficiency and motivation and safeguard the success of the business against the background of the extremely dynamic processes of change. Maintaining and promoting the health of all employees, weather in operation, administration or on the mining site, has become therefore not only an ethical requirement but also an economic must. Creating a suitable working environment for people today entails much more than just preventing accidents and work-related illnesses. It is important to be proactive in establishing an even better culture of prevention and to convince everyone, workers and managers alike, of its importance. Especially in the age of rapid changes and above all in view of global competition we are more dependent than ever on healthy, enthusiastic, competent and creative employees. OHS provides you with the necessary competitive edge.

Jan 1, 2007

By G. J. Joy

Although rates of pneumoconiosis in coal miners have declined substantially in the United States since the passage of the Federal Coal Mine Health and Safety Act of 1969, new cases continue to occur, including cases of rapidly progressive disease. In contrast, Australia?s underground coal mining industry has reported few new cases of pneumoconiosis for over twenty years. Mortality from Coal Workers? Pneumoconiosis in official health statistics and the prevalence of pneumoconiosis among miners screened in x-ray surveillance programs are also lower in Australia. To understand this disparity, the National Institute for Occupational Safety and Health was requested by both industry and labor stakeholders to examine this issue, with the ultimate aim of reducing the rate of pneumoconiosis among United States coal miners. A number of factors, including coal dust exposure, silica exposure, and coal rank were examined as potential contributors to the above observed differences. Comparison of coal rank data from each country did not show any significant differences. Air sample data from the coal mining industries in both countries show that coal dust levels in Australian mines are somewhat higher than those reported in similar U.S. mines; however, quartz exposure for Australian miners is lower than for many U.S. miners. Assuming that quartz is contributing to the greater number of cases of advanced pneumoconiosis in the U.S., more effective dust control measures, as well an independent exposure standard for respirable quartz in coal mining, need to be implemented to prevent this potentially disabling condition.

Jan 1, 2011

By E. M. Spokes

Starting in 1980, a committee of the National Research Council studied the question of why some underground coal mines are safer than others and what could be done to improve the ones with poorer performance. The results indicated that safety is improved by management commitment to safety, by cooperation between labor and management on safety matters, and by quality training of employees and managers. Younger miners have higher accident frequencies, but are less likely to be killed or permanently disabled by a lost-time accident. Methods for improving safety performance are proposed.

Jan 1, 1987

By T. R. Ellis

A number of important international events took place in 2001 in the development and evolution of mineral valuation standards internationally. In Canada, the CIMVal Committee released a draft discussion paper for public and industry comment on principles to guide the development of the planned Canadian mineral property valuation standard. The International Accounting Standards Board (IASB) received comments on its Extractive Industries Issues Paper. IASB will decide whether the financial statements of public mining and petroleum companies will be allowed to provide the value of mineral and petroleum assets on a current value basis instead of an historic cost basis. The author led the Extractive Industries Task Force of the International Valuation Standards Committee (IVSC) in developing its submission to IASB. IVSC intends to develop an extractive industries valuation section for its International Valuation Standards, which could support the planned IASB standard. In Australia, AusIMM has carried out an in-depth review of its highly regarded VALMIN Code. The AusIMM's MICA subdivision organized the VALMIN ‘01 Conference in Sydney, Australia, with a range of international and current issues papers published in the VALMIN ‘01 book. Considerable support for the IVSC initiative was evident at this conference. The results of the review of the extractive industries submissions to the IASB are expected to be released in early 2002. The CMMI Congress in Cairns, Australia in May 2002 is likely to prove to be an important forum for continued discussion of the development and implementation of international standards and qualifications for mineral valuation. The outcomes and implications of these events are discussed.

Jan 1, 2002

By William R. Yernberg

What a difference a year makes. One year ago, the iron mining industry and the steelmaking industry in the United States were in trouble. Many companies were in bankruptcy, and talk of plant and mine shutdowns was rampant. At that time, it seemed difficult, if not impossible, to remain competitive with imported steel. In addition, the World Trade Organization declared as illegal the tariffs placed on imported steel. And many questioned the viability of the ironmining and steel industry in the United States. At that time, global economic conditions were the main contributors to the industry’s problems. However, since last year’s meeting, changes in global economics have actually helped the steel industry in the United States. Heavy global demand for steel has caused raw-material shortages worldwide. Much of the increased demand is a result of the economic boom in China. In addition, because of a weak U.S. dollar and higher international freight rates, steel imports into the United States have been reduced to about 50 percent of recent levels. These factors have contributed to a rebirth of the U.S. iron mining and steel industries.

Jan 1, 2004

By Leonard N. Hill

Cyprus Sierrita Corp. has 16 parallel 5.03 m-diam x 5.8 m long (16.5 ft-diam x 19 ft) primary ball mills, each operating in closed circuit with a nest of cyclones. Before the upgrade to 840 mm (33 in.) cyclones, each mill operated with a nest of five 660 mm (26 in.) cyclones - four in use and one on standby. In this configuration, the mill throughput was 88.5 kt/d (97,500 stpd). Flotation feed averaged 25.9% +212 pm (+65 mesh). The 660 mm (26 in.) cyclones normally operated at an inlet pressure of 34 kPa (5 psi), lower than the inlet pressure of 55 kPa (8 psi) recommended by the manufacturer. The circuit was typically operated with cyclone overflow densities greater than 40% solids to achieve the required throughput. This resulted in inefficient cyclone operation and excessive coarse oversize reporting to flotation. The apexes choked frequently. Larger apexes were tested but reduced the classification efficiency and resulted in circulating loads greater than 800%.

Jan 1, 1994

By Andrew Kaczmarek

The mining industry is enjoying a much needed and long awaited increase in demand for natural resources. However, consolidations in the mining and mining service industries, along with a generational departure of experienced industry professionals, is challenging today’s mining companies. These challenges are not only in maintaining their existing operations, but also in securing qualified resources for developing new projects. These challenges are compounded for junior mining companies. They oftentimes lack for operating properties to draw experienced professionals from. Also, juniors have to compete with the majors’ “mega-projects” for experienced project personnel from the reduced ranks of engineering companies. This article discusses some strategies developed by Anatolia Minerals Development (Anatolia) in developing its Çöpler gold project in central Turkey.

Jan 1, 2006

By David van Cleave, David L. Rome

Whether you buy your minicomputer from a manufacturer or another vendor, the first thing you must do is define your needs. With good planning, the initial cost will be low and your return on investment will be maximized over the long term. Involving all members of your staff who will he using the new computer in the planning phase is also important. Their participation will alleviate any potential concerns they may have about new equipment, and their suggestions will provide valuable input for your specifications. After you define your proposed system, survey available hardware and software. The survey will help you in the next step, preparation of specifications. The specifications, along with a quote request, are then sent to various manufacturers. Consider the Manufacturer When selecting your minicomputer, one important item to consider is the manufacturer. Remember, when you buy a computer, you're also buying the services of a computer company. A firm that makes a commitment to its customers and provides a product that is field tested before releasing it for sale is preferable. Examine the company's maintenance and support packages, since every machine requires preventive maintenance. Does your manufacturer or original equipment manufacturer (OEM) support service sites in your area? Has their service record been commendable? Will they provide training for your personnel and a supply of circuit boards so you can retain a degree of self-service autonomy? Three methods of buying a computer involve the manufacturer, an OEM, and the systems house. Buying direct from the manufacturer means you go straight to the source, using no middleman. This gives you maximum flexibility; you can consider every alternative and many possible combinations of computers, peripherals, and software until you find exactly the right system for you. The OEM buys computers direct from the manufacturer and builds them into his own computerized, special purpose product. He usually sells a complete package, including software and hardware, and often noncompetitive equipment as well (a scientific or engineering instrument, for example), designed for the mining market. Because he offers a packaged product, the OEM can often charge less for the system than if you put the pieces together yourself. In many ways, the OEM also provides a unique system. And while the OEM sells a packaged solution, he also usually has the special market knowledge necessary to modify the system to meet your unique needs, if necessary.

Jan 11, 1981

By Tim O’Neil

“America’s mining industry brings good jobs to communities across America and provides the energy, minerals and equipment that are vital to our economic security and our way of life.” That was the surprise videotaped greeting from President George Bush at the official opening ceremony of MINExpo 2004in the Las Vegas, NV Convention Center. Jack Gerard reinforced the upbeat mood at MIN-Expo. He praised Nevada Gov. Kenny Guinn for his support of the mining industry, the state’s largest manufacturing sector. Gerard is the president and chief executive officer of the National Mining Association, the sponsor of MINExpo 2004.

Jan 1, 2004

By V. T. McLemore

In-situ leaching (ISL) operations have been proposed to recover uranium from sandstone-uranium deposits in NM. ISL (also known as in-situ recovery, solution mining, solution-leach mining, leach mining) consists of injecting a leaching solution into the mineralized zone through injection wells. The leach solution migrates through the formation, dissolves uranium and is recovered through production wells. The uranium is then precipitated through a conventional uranium recovery system. Several criteria must be met in order for in-situ leaching to be successful, most important is that the ore body must be amenable to chemical leaching. A number of ISL operations have been conducted in NM in the past (Mobil, Crownpoint; UNC-Teton, Section 23; Grace Nuclear, Hook?s Ranch, Seboyeta, Church Rock; Anaconda, Windwhip). Kerr-McGee (later Quivera Mining Co., Rio Algum) successfully produced uranium from mine-water recovery (recirculated mine water) from the Ambrosia Lake mines (mid-1960s to 2002). Despite some difficulties, ISL is a viable alternative to recovering uranium and could be utilized in the Grants district with proper aquifer characterization and monitoring.

Jan 1, 2009

By D. J. Barratt

The application of autogenous and semi-autogenous grinding circuits in recent years has contributed toward substantial savings in capital and operating costs compared to conventional circuits, particularly for large scale copper and molybdenum operations. Such savings have been realized from the deletion of operating, maintenance, equipment purchase and substantial civil/structural costs associated with secondary-/tertiary crushing and screening, fine ore storage and conveying. In spite of the downturn in the copper- moly industry in North America, there is still an interest in autogenous and semi-autogenous grincting for copper-zinc, gold and silver ores and in the overseas market. Both single-stage and two-stage circuits are in operation. Primary circuits operate autogenously or semi-autogenously in either open or closed-circuit. Critical sizes are extracted and crushed for recycle in some cases (e.g. ABC circuit). Secondary grinding is conducted using ball mills or pebble mills.

Jan 1, 1985