Search Documents

By Unto Paakkinen

The testing of different kinds of process flow configurations and cell volumes in industrial scale flotation processes is in general difficult to accomplish and even expensive to perform.1 Also the lack of suitable measuring and analyzing devices often prevents effective comparison of results. Nowadays, the existing flotation processes contain, almost with exception, several return loads which result in difficult control of the process. There exist two good reasons for testing different kinds of flotation circuits at the Outokumpu Oy Kotalahti mine. Firstly it is easy to change the process flow configuration without any additional installation work and secondly, the concentrator is highly automated with magnetic flow meters, on-line analyzer and process computers. In this presentation, open circuit flotation is compared with the classical closed circuit flotation which contains return loads. In additional, the effectiveness of computer control in both cases is estimated and also the effect of cell volume on flotation results is examined.

Jan 1, 1977

By Frank E. Chase

Preventing pillar squeezes, massive pillar collapses, and bumps is critical to the safe and efficient recovery of coal during room-and-pillar retreat mining. To help prevent these problems, the U.S. Bureau of Mines (USBM) has developed the Analysis of Retreat Mining Pillar Stability (ARMPS) computer program. ARMPS calculates stability factors (SF) based on estimates of the loads applied to and the load-bearing capacities of, pillars during retreat mining operations. The program can model the significant features of most retreat mining layouts, including angled crosscuts, varied spacings between entries, barrier pillars between the active section and old (side) gobs, and slab cuts in the barriers on retreat. It also features a pillar strength formula that considers the greater strength of rectangular pillars. The program may be used to evaluate bleeder designs as well as active workings. A data base of 110 pillar retreat mining case histories has been collected across the United States to verify the program. It was found that satisfactory conditions were very rare when the ARMPS SF was less than 0.75. Conversely, very few unsatisfactory designs were found where the ARMPS SF was greater than 1. 5.

Jan 1, 1995

By Neil D. Policow

Dewatering of the fine clean coal fraction, - 28 mesh (595 microns) represents one of the most difficult and costly separations in typical plant circuits. Since 1969, the Screen Bowl Centrifuge has offered an economical alternative to filtration/thermal dryer combinations. The performance of Screen Bowl Centrifuges has been continuously modified and improved to dewater not only coarser coals, but also today's variety of ultrafine material. Actual test comparisons with alternative methods show the Screen Bowl Centrifuge to be most cost effective and efficient when all factors are considered.

Jan 1, 1982

By S. C. Torma

Sources of lead contaminated soils are numerous, i.e., the uses of leaded gasoline, lead-based paints, leaded pesticides, solders, smelting of lead concentrates, refining of lead products, automobile demolition, recycling of lead batteries, and so on. Conservative estimation by the US Environmental Protection Agency, EPA, indicated that several thousand lead contaminated sites are awaiting remediation. The current remediation technologies include immobilization, reclamation and soil washing. In this paper, the above remediation technologies will be reviewed, and where appropriate, the economics of processes discussed and future possibilities indicated.

Jan 1, 1996

By Siegmund Babendererde

1. Introduction In Sayreville, New Jersey, the Middlesex County Utilities Authority put the construction of a 1041 m long sewer outlet to tender in June 1989. It had an internal diameter of 3,36 m and was part of a sewage treatment works project for county Middlesex. The contract was awarded to the Lodigiani Company, USA, who employed Hochtief Incorporated as subcontractor to drive the sewer outfall. 2. Ground Conditions According to the preliminary geological site investigation, carried out by the consultants Metcalf & Eddy, the tunnel passed through marine deposits.

Jan 1, 1991

By R. K. Rajamani

The theoretical model based on fluid mechanics, in conjunction with the laser-Doppler velocimetry (LDV) measurements, elucidate the size-classification mechanisms in an industrial hydrocyclone. The model has no adjustable parameters and involves solving the Navier-Stokes equations to predict the liquid-phase velocities. The spatial-concentration gradients were determined considering the particle phase in the Lagrangian frame and the classification curve was determined by balancing the forces acting on the particle. The force balance requires liquid velocities, which in turn depend on the local volumetric concentration of the particles. Hence, complete modeling work involves coupling both the concentration and liquid-phase velocity calculations until convergence is reached. Finally, the experimental and predicted classification curves were presented for 250-mm hydrocyclone operating at high-percent solids.

Jan 1, 1994

By B. K. McMahon

Block caving is an efficient mass-production method for the underground mining of large orebodies. However, the block-caving method requires a substantial investment in developmental works, based on the assumption that the rock will cave. Efficient block caving is prevented if the rock forms stable arches or breaks into fragments that are too large to pass easily through the finger raises. Under these conditions, the cost of the additional labor, drilling, and blasting required to assist caving may be sufficient to make marginal orebodies uneconomic or alternative mining methods more attractive. Reliable methods for the prediction of the block-caving behavior of an orebody are clearly needed at the initial planning stage. These methods should be capable of considering both geological and engineering aspects of a block cave, as experience has shown that the manner in which a block cave is initiated and developed may be almost as important as the geological conditions such as the nature of the rock material, degree of alteration, characteristics of the joints and faults, etc. The initial state of stress in the rock mass should also be considered.

Jan 1, 1969

By Michael Karmis

"In December 2011, the U.S. Attorney’s Office for the Southern District of West Virginia, the U.S. Department of Justice, Alpha Natural Resources (ANR) and Alpha Appalachia Holdings entered into a nonprosecution agreement related to the explosion at the Upper Big Branch Mine (UBB) that killed 29 miners. This coal operation was owned by Performance Coal Co., an affiliate of Massey Energy Co., which was acquired by ANR in June 2011, more than a year after the UBB explosion. Pursuant to the agreement, ANR agreed to:• Establish a trust within 120 days.• Pay a total of US$48 million into the trust to be used solely to fund and administer research and development (R&D) projects to improve mine health and safety.• Administer the trust by three highly qualified individuals with academic and/or professional backgrounds in mine health and safety.In April 2012, the Alpha Foundation for the Improvement of Mine Safety and Health was created. The three directors - Michael Karmis, president; David Wegman, vice presidenttreasurer, and Keith Heasley, vice presidentsecretary - approved a plan to expend both the interest and principal of the trust, aiming at an 8-10 year research horizon. The foundation also appointed David Belden, an experienced manager of nonprofits and professional associations, as the first executive director of the foundation. The IRS approved the foundation’s tax-exempt application, as described in Section 501c(3) of the Internal Revenue Code, on Dec. 18, 2012. The board established guiding principles of the foundation, which are as follows:• Mission: to improve mine health and safety through funding R&D projects to qualified academic institutions and other not-for-profit organizations.• Vision: to enable miners in the future to be free of work related injury or disease by the implementation of the results of the projects funded by the foundation and undertaken by the best researchers from any discipline that can contribute. The foundation is now approaching its third year and regularly posts updates, including semi-annual reports, to its website (www.http.alpha-foundation.org/), which serves as the main medium for communication with the broader stakeholder community"

Jan 1, 2014

By Ted H. Eyde

Specialty sand and bentonite are produced in the plateau province from the Bidahochi Formation near Sanders, Apache County, Arizona. It appears that deposits of both sand and bentonite formed during the Pliocene in fluvial and lacustrine environments, respectively, along the west side of the Defiance Uplift. The bentonite is an alteration product of airborne vitric ash that fell or was washed into lakes. In the Cheto district, the individual bentonite horizons, which range from less than a foot to more than 10 feet thick, are restricted to the position of the medial volcanic member. Bentonite production began at the Allentown mine in 1924 and the Chambers mine in 1926. In 1933 strip mining of the extensive deposits in the Cheto district commenced. Production increased each year to a peak of 270,000 tons in 1957. As a result of the introduction of synthetic zeolites into petroleum refining, production declined. About 40,000 tons of bentonite are currently produced from the district each year. Bentonite is shipped out of State for processing into desiccants, thickeners, and acid-activated clay products. The specialty sand was derived from Permian sandstones and deposited by streams draining the Defiance Uplift. Although stream channels are usually restricted to the upper member of the Bidahochi, stratigraphically above the bentonite horizon, a few actually cut through the bentonite. The well-sorted sand, suitable for use as a proppant in hydraulically fractured oil and gas wells, is localized in elongate lenses along the margins of the channels. These lenses range from 5 to 50 feet in thickness and often extend thousands of feet in both width and length. The sand is about 97 percent silica, has a yield of 40 percent in the minus 20 plus 40 mesh size fraction, and has a roundness of 0.6 to 0.7 on the Krumbein scale. Production of this sand began about 1961. All of the current production, which amounts to about 40,000 tons per year, is sold in the petroleum-producing area near Farmington, New Mexico.

Jan 1, 1987

By T. Szwilski

The Appalachian coal region is an area here the small mining operation dominates. The large number of small operations makes the coal industry in chat area very competitive, the industry concentration ratio being low. This feature is reflected in the nature and behavior of the coal supply and demand viz a viz the coal market. The vast majority of the small coal operations in Eastern Kentucky for example, are contractors. The circumstances under which a large mining company can elect to use contractors to supplement their coal production are examined. The pros and cons of small underground single unit mines and larger multiple unit mines are discussed.

Jan 1, 1986

By Jr. Pickering

Kaolin is mined from extensive sedimentary formations in the eastern Amazon River Basin of Brazil. Production began about 25 years ago from 30 meter thick beds of ultra-fine particle clay of superior viscosity along the Jari River north of the Amazon. Operated by CADAM S.A., capacity now exceeds 750,000 tonnes per year ot high glossing paper coating kaolin product. South of the Amazon on the Capim River are two new operations: Para Pigmentos S.A. and Rio Capim Caulim S.A. The purity , and large coarse plate-shaped particles of these Capim kaolins support production of superior brightness and whiteness paper coating and filling grades. Annual capacities are reported to be 150,000 to 300,000 tonnes each, with expansions planned. Most of Amazon area kaolin production is shipped to western European, Asian, and North American markets.

Jan 1, 1999

By Michael M. Kimberley

Stratiform uranium deposits occur in Canada along the north shore of Lake Huron near the base of the Middle Precambrian Huronian Supergroup. Outcrop of the Buronian Supergroup extends for over 400 km from Sault Ste. Marie in the west eastward through Sudbury and then northeastward to Cobalt. Maximum stratigraphic thickness exceeds 5 km. The predominant Huronian rock type is metamorphosed sandstone (quartzite), with sub- ordinate argillite, conglomerate, mixtite (possibly tillite), volcanic rocks, and minor limestone, Much of the quartzite is highly feldspathic. Substantial uranium ore was first discovered in Huronian rocks in 1953 and has been exploited continuously since the initial mine-mill plant was constructed at the Pronto ore body, 30 km south of the present townsite of Elliot Lake. Only one ore body remains in production, however. It is shared by Rio Algom and Denison Mines 14 km north of the town of Elliot Lake.

Jan 1, 1980

By R. L. Bleifuss, S. Zhong, H. E. Geotzman

Microwave heating of iron ore was investigated as an alternative to conventional reduction processes to solve the problem of slow heat transfer. Microwave heating and reduction tests were run on composite green balls made from coal and magnetite concentrate. Benchscale tests were run on both powdered and pelletized feeds using a 15 kW microwave generator. A significant increase in the reduction rate was obtained. With 20% excess stoichiometric carbon in the mix, more than 90% reduction of the iron ore can be achieved in about 10 min at temperatures of around 1,000°C. The reduction of iron ore with coal by microwave heating produces a pure, dust free, high-Btu flue gas that can be used in related thermal operations. Depending on the purity, the reduced iron product could be fed directly to an electric arc furnace for melting. In some cases, the removal of a slag phase may be required to eliminate excess silica and alumina.

Jan 1, 1997

By D. Watson

The Henderson mine has more than 20 years experience and has placed a combined total of more than 400,000 m3 (520,000 cy) of shotcrete and concrete. Over the last 20 years the mine has used a variety of equipment for placing concrete, wet shotcrete and dry shotcrete and is constantly trying to cut costs and increase efficiencies. Henderson has recently received a state of the art wet shotcrete placer, automated its batch plant, fabricated a mobile concrete form jumbo and is soon to receive a new concrete transport truck.

Jan 1, 1992

By M. A. Sochocky

Rod mills were developed, as a logical substitute for the rolls crusher when larger tonnages had to be handled, on a continuous basis. Today, with even larger tonnages to process, the trend is to install larger equipment, automate the plant and develop the highest availability possible, in order to cut costs. The rod mills, because of design limitations in size and speed 1'2, are not able to meet these new requirements. The autogenous mill was a timely development and serves as an excellent alternative for ores that are suitable to this type of grinding. When ores are not amenable to autogenous grinding, selection of a flowsheet is dictated by liberation characteristics and unit operations to be used for mineral recovery.. The following alternatives are available: (a) Multiple rod mills, capable of drawing no more than 2000 HP each, followed by ball mills. (b) Gyradisc crusher followed by two stages of ball mill grinding.3 (c) Tertiary crushing followed by closed circuit single stage ball mills grinding to approximately -100 mesh, as in the copper industry. (d) Tertiary' crushing followed by two-stage, ball milling. Each stage will operate in closed circuit with either screens or cyclones. It is this last alternative, particularly as it

Jan 1, 1972

By Y. J. Wang

In the, mathematical analysis of electrical networks, the electrical devices are often modeled using idealized network elements such as current sources, voltage sources and resistors. An analogous approach is outlined for the modeling of mine ventilation networks, which can be considered nonlinear resistive networks. The proposed modeling technique uses the following five basic (nonreducible) elements: H, Q, D, R and N. These elements are characterized by their pressure gain or loss, their air quantity and their pressure-vs. -quantity relationships, each of which may be known or unknown. In addition to the definition of the basic elements, the necessary conditions for which there exists a unique solution are discussed This is performed using theoretical developments derived from electrical circuit theory and illustrated in example networks. The proposed procedures are useful in the solution and characterization of mine-ventilation networks.

Jan 1, 1997

By L. Barnewold, A. Merchiers, M. Pütz, P. Jeschke, M. Dammers

The mining industry faces many difficult challenges, for example, lower ore grades, smaller and deeper deposits, and longer transportation distances. In the past, there have been remarkable innovations in both equipment and the types of mining methods for which it is used, which have resulted in economies of scale. This has led to an increased use of bulk mining methods, like sublevel and block caving, which has increased productivity and reduced costs. Haulage alone plays a major role. Current haulage techniques are a significant cost driver, which account for between 15 and 30% of the overall capital investment (capex) in a mine and are an increasingly part of the operating costs (opex). The paper introduces a simulation tool of main haulage system in underground mining. Therefore, performances and the costs of the three most common underground main haulage systems, rail, truck, and conveyor, are calculated using a developed modeling tool. The tool was applied and validated in a case study carried out with the LKAB Kiruna Mine in northern Sweden.

By J. E. Lonergan

The in-pit placement of crushing and conveying equipment results in a flattening of the pit slope of a multiple-bench open pit mine. To maximize the economic benefit of lower haulage costs associated with in-pit conveying, one must minimize the cost of the flatter slope which is expressed in terms of additional stripping or tied up ore. A computer program that compares the tonnage aspects of various conveyor layouts will be discussed.

Jan 1, 1985

By Mahiyar Nasarwanji, Jonathan K. Hrica, Jonisha P. Pollard, Lydia M. Kocher, Brianna M. Eiter

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and nonfatal injuries that occur in mining in the United States. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the U.S. Mine Safety and Health Administration (MSHA) from 2010 through 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84 percent involved the workers not using fall protection, fall protection not being provided or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment or working near highwalls. In most cases, a single, basic, corrective action — such as using fall protection — would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

By L. D. Boughton

Solution mining projects are conducted through one or more boreholes which penetrate en ore body. Proper drilling, completion and maintenance of the boreholes, therefore, is essential to the success of any solution mining operation. Wells drilled for solution mining encounter problems quite similar to problems encountered by the petroleum industry in drilling, completing and maintaining wells for the production of oil, gas or water. Many of the services developed and much of the experience gained by the petroleum industry is applicable to solution mining wells. As in the petroleum industry, each individual wellbore and ore body in a solution mining project provides its own problems. These vary greatly from well to well, and it is not possible to set down data or outline programs that will apply to all wells. Instead, the design of the drilling, completion, production and maintenance programs should be worked out for each individual well. The purpose of this paper, then, is to generally describe materials, equipment and techniques available for these programs and to discuss the purpose and sequence of their use.

Jan 1, 1971