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By Charles E. Glass

As partial implementation of the Surface Mining Control and Reclamation Act of 1977, the Office of Surface Mining (OSM), Department of Interior, has requested each state to inventory hazardous abandoned mining areas within their boundaries. Primary interest is in such areas .as unstable waste-banks, subsidence and slumping, contamination of water supplies, and preservation of overall aesthetic qualities through reclamation. In addition to the concern expressed for abandoned mining areas, the legislation requires a complete inspection of operating mines quarterly and a partial inspection monthly. In Arizona copper has been mined for over 100 years and coal and uranium mining promises to expand in future years. The OSM requirement for a waste inventory and frequent monitoring of Arizona's large, widely spaced mines places a severe demand on limited personnel and operating budgets. Remote sensing by satellite provides an attractive and effective approach to aid the inventory and monitoring requirements of the OSM legislation.

Jan 1, 1979

By D. Lelinski, R. Bokotko, J. D. Miller, J. Hupka

Air-sparged hydrocyclone (ASH) flotation is a new, promising technology, and, since its conception, numerous applications have been successfully tested. Nevertheless, research and development efforts have continued to improve the technology with respect to operating conditions and design considerations. Results, from experimental studies on bubble generation in the ASH system are presented in this paper. Bubble size distributions generated during ASH operation were determined using a high-speed photographic technique. The influence of many factors, including surfactant concentration, water flow rate, and porous-tube pore size have been studied. Test results indicate that these process variables have a profound effect on the bubble size distribution. With an increase in surfactant concentration or water flow rate (shear field), the bubble size distributions become narrower and shift toward smaller average bubble diameters. However, the influence of pore size is more complicated. Depending on the experimental conditions, the average bubble size was found to range from about 100 to 300 µm in diameter.

Jan 1, 1997

The National Institute for Occupational Safety and Health (NIOSH) conducratory and field tests to evaluate the effectiveness of dust collector bags for reducing dust liberation and operator exposure from a roof bolter?s dust collection system. The laboratory tests evaluated the bag?s effectiveness to contain dust and the effect on canister filter loading in both a bag and bagless condition. The dust emissions from the collector?s exhaust were also measured in each condition during laboratory testing and show that nearly 100% of the test dust fed into the collector was captured by the dust bags. Loading and pressure drop on the dust collector?s canister filter is greatly decreased when using the bags, enabling longer periods of drilling without filter removal/cleaning. The field results showed that, even though dust standards were met, respirable dust in exhausted emissions was reduced around the bolter. Laboratory and field results show that benefits from use of the bags are realized in all areas of operator exposure.

Jan 1, 2008

By P. V. R. Bhaskar Sarma, P. K. Sahoo, G. Roy Chaudhury

A process was developed to treat an ammoniacal leach liquor containing zinc using Di (2-ethyl hexyl) phosphoric acid (D2EHPA) as the extractant. The objective of this work was to develop a process package for the treatment of complex sulfide leach liquors. Zinc extraction could not be carried out directly from the ammoniacal solution in mixer-settler units because of crud formation and low extraction efficiency. After neutralizing the free ammonia with H2SO4, the extraction efficiency was only about 40%, due to the high concentration of (NH4)2SO4. To decrease the (NH4)2SO4 concentration, the free NH3 was steam stripped, and the resultant liquor was subjected to zinc solvent extraction. An extraction efficiency of 98% could be achieved by controlling the equilibrium pH. Stripping studies were also optimized after removing ammonia from the zinc-loaded organic. A continuous 100-hr operation that included extraction, scrubbing and stripping, was carried out successfully.

Jan 1, 1995

By R. F. Kovar, R. N. Torbin

Foster-Miller has recently developed a new concept for a highly specialized shaft lining system. This innovative shaft lining system uses a continuous slip forming placement technique, lining the shaft from the bottom up such as in a raised bored shaft. Although this part is not unique, the concept is designed to use polyurethane foam instead of concrete for the liner material. Furthermore, the concept is designed to attain rates of advance of 30 m/h (98 fph). The polyurethane foam liner is designed to be thinner (100 mm or 4 in.) than a conventional concrete liner (300 mm or 12 in.). It will eliminate the high cost associated with the erection and operation of an on-site concrete batch plant. The system will be designed to operate remotely, requiring few personnel for its operation. This system (or parts of it) may be appropriate where fast construction speed is required or where a jointless liner is needed.

Jan 1, 1990

Political events during the past decade have caused businesses throughout the world to think globally. Countries once closed to free market enterprises are now open and seeking out foreign investment to help improve the well being of their populations. The mining industry has always been a global one. Today, though, the industry has become even more global. The driving forces behind this include the opening up of higher grade, lower cost mineral deposits in undeveloped and developing nations. In addition, permitting delays in the United States, coupled with stricter environmental guidelines and a general anti-mining attitude, have forced the mining industry to look outside US borders. The Mineral Economics and Management Society (MEMS) took as the theme of its seventh annual professional program "Economic Globalization of the Mining Industry." About 100 people attended the conference held in Arlington, VA in late March. Speakers included members of the investment community, academia, government and the mining industry.

Jan 1, 1998

By Harold Wahlborg, George Owusu

In a study using butyl diglyme as an organic extractant, essen­tially complete extraction of gold from chloride leach solution was achieved. The extraction kinetics are so fast that the process could be completed in 30 seconds. Except for iron, co-extraction of other ionic species was insignificant. Co-extracted iron species were successfully scrubbed from the loaded organic using 10% HCl solution. High grade, >99.9%, gold was recov­ered from the loaded organic using 5% oxalic acid solution as the stripping agent at a temperature of 70°C to 80°C. Over 99% of the organic-loaded gold was stripped from the organic phase. The butyl diglyme extractant is being tested on a variety of gold-bearing feedstocks. Presented here are results obtained from two gravity concentrates.

Jan 1, 1999

By William D. Leech, Peter S. Buskirk

Virginia Electric and Power Company commencing in early 1985 will begin operating the Bath County Pumped Storage hydroelectric facility, presently the largest capacity installation of its kind. Six concrete lined vertical shafts, 3 ea x 44.0 ft (13.4m) diam x 330 ft (100m) and 3 ea x 28.5 ft (8.7m) diam x 740 ft (226m), comprise a portion of the three underground power conduits. The project team decided to employ the slipform over the conventional jump form method. This selection was based on the engineer's hydraulic design and the contractor's performance requirements. This paper presents the key elements of the shafts' successful slipform operations. The contractor achieved slip rates as high as 60 ft (18m) per day; and the owner received competent permanent linings as specified by the engineer. The authors describe the team's effort to progressively improve both concrete quality and placement rate.

Jan 1, 1985

By B. Das, D. D. Mishra, M. I. Ansari

Experiments conducted with a 75-mm-diem hydroryclone have shown it is possible to obtain an iron ore concentrate containing 60% Fe. 2.65% SiO2, and 4.0% Al2O3 from Barsua iron-ore washing-plant slimes. About 60% of the iron values are recovered from slimes containing approximately 49% Fe, 8.9% A1203 and 11% SiO2. The obtained products can be used in the sinter feed for iron and steel making. The key to achieving process success lies in establishing the correct cut point (d50) of the hydrocyclone through the manipulation of operating and design variables, such as spigot and vortex finder diameter, solids concentration and operating pressure. The cyclone efficiency is represented by the partition curve. The cyclone performance, evaluated mathematically from the reduced efficiency curve, is represented by the equation Y = 100[1 -exp(-axb)], where: •X = did 50, •Y = corrected of efficiency (%) and •a and b are constants.

Jan 1, 1994

By Nancy C. Shaver, Alan Tapp

Leach pads of 272,000 tonnes (300,000 st) and 910,000 tonnes (1,000,000 st) with associated operating ponds have recently been constructed on sidehill locations with up to 20 percent slopes. The larger pad was designed in anticipation of ore heights up to 30 meters (100 feet). This paper describes site investigations and civil engineering design as well as construction experience associated with development of these pads. The leach pads were underlain by a double liner system consisting of 2 mm (80- mil) HDPE over compacted fine-grained tailings, with an intermediate leak detection layer. Both sand and geotextile drainage layers were used. Pad slopes were limited by the factor of safety against sliding on the HDPE liner. The sites for the facilities had been substantially disturbed by prior mining and construction activities. Natural conditions included peat layers and locally swampy ground. Site preparation included french drains to lower the water table and stripping of unsuitable subgrade materials.

Jan 1, 1987

By Pierre M. Gy

The final purpose of exploration is to esti- mate the grade and tonnage of the various qualities of ore contained in a given mineral deposit. This estimation cannot be directly carried out on the whole of the ore body. It usually requires four steps: Core Drilling Campaign The ore body is represented by a series of cores further divided into core sections of equal or unequal length. Core Splitting The core sections are longitudinally split into two halves: the first half is kept for various examinations and physical measurements, and stored for further reference; the second half (core sample) is used for determination of the chemical analysis. Core Sample Reduction The chemical analysis cannot be directly per- formed on the core samples. It requires the constitution of assay portions usually weighing from a few decigrams to one gram (more in precious metals assaying) and passing through a 100 or 150 mesh screen.

Jan 1, 1979

By PDF

Previous work has shown that significant, free milling gold values exist in the Ryan Lode ore. This project used pilot scale equipment to estimate the percentage of gold recoverable by gravity methods from the circulating load of a conventional, closed-circuit, grinding mill. The pilot scale flowsheet employed three stages of gravity concentration, hydraulic classification and batch grinding to simulate a full scale milling circuit. 172 kg (379 lbs) of Ryan Lode ore were processed, having a head grade of 4.8 g/metric ton (0.14 oz/ton). Results showed that simple gravity methods are capable of recovering 45-50% of the gold values in a concentrate grading in excess of 3430 g/metric ton (100 oz/ton). Of the remaining gold values reporting to the classifier overflow solids (80% passing 70 microns, 3.1 g/metric ton (0.09 oz/ton)) 89% were recovered from 48 hour bottle roll tests.

Jan 1, 1995

By Bernie W. Martin, Duncan MacLennan

Building a new tunnel to accommodate CN North America's needs for double stacked container traffic for the next 100 years presented new and unprecedented challenges. Innovative approaches to contracting, especially the Negotiated Compressed Process (NCP), TBM design, project management, and the regulatory and approval process, were all required to deliver a new tunnel to meet the needs of CN North America within the approved completion schedule of 39 months compared to a traditional approach of 45 to 48 months. The NCP resulted in trimming 6 to 9 months from the project schedule, at a great saving of direct and indirect costs. The Negotiated Compressed Process is an innovative formalized approach to risk sharing for complex infrastructure projects. Ads were placed in the international trade journals and a short list of "approved" contractors and suppliers was developed. The approval process for this international project involved contacts with over two hundred agencies, departments and interested stakeholders.

Jan 1, 1995

By Philip D. Lindahl

The US Bureau of Mines (USBM) began research to improve the safety and efficiency of transporting coal from underground coal mines using a balanced air-lift hydrohoist (ALH). ALH includes a U-tube pipeline that can be installed through an existing shaft or two surface-drilled holes connecting the mine level to the surface. Bench- and pilot-scale models were tested to evaluate the feasibility of hydraulically hoisting a coal-water slurry in a riser pipe by injecting compressed air microbubbles. A prototype injector was developed that continuously compacted -50-mm (2-in.), run-of-mine coal in a screw feeder and injected a thick coal slurry into ALH. Initial production rates of 40 t/h (44 stph) through a 200-mm-(8-in.-) diam riser pipeline were achieved with a50-m- (165-ft-) high pilot-scale model. The potential productivity was expected to increase to 100 t/h (110 stph) through modification of the coal injector.

Jan 1, 1995

By Darryl Amick, Keith A. Prisbrey, Lee E. Plansky

The problem addressed was to develop automated image analysis of metal welds to replace unreliable and costly 100% visual inspection. The objective was to evaluate neural networks combined with features from gray level surfaces. Photomicrographs of the welded seam in Zircaloy-4 channels used in nuclear fuel rod assemblies were examined. The methodology used was to select a set of morphological feature coefficients from Bessel Fourier morphological feature coefficients extracted from digitized photomicrographs. The selected morphological feature coefficients were then used to train a neural network. The approach was verified initially by successfully training a neural network using the known, secondary chemistry of the alloy welds. The results were good. The Bessel Fourier coefficients captured sufficient information from the metallographic images to distinguish weld quality. This approach has the combined advantages of compressing the images through Bessel Fourier coefficients and give the ability to rapidly process large amounts of data using neural networks.

Jan 1, 1993

By W. W. Hartley

Following a Major underground coal mine incident there followed a review of the role of mines rescue ? the Queensland Mines Rescue Brigade. It wasn?t until 2002 that the real change started to happen. The issue of geographical distance was addressed by mines rescue sub stations being located on the mines sites with parent rescue stations in a central location. The funding was by means of a levy on the mining industry with legislative standards and performance included. The previous Rescue Brigades were not well organised (central districts) and the application of recognised quality management practices within local management was lacking. The structure was based on other nations models and miners managing miners was an issue for the organisation. The reform was some what painful and the QMRS organisation will still evolve with continuous improvement. Queensland has the National Champion mines rescue team for the eighth year. QMRS is participating at the level in the industry of influencing emergency systems and training senior mine management in ?Emergency Mine Management? coaching the industry in emergency response systems. We have come a long way. We have had some success and there is always the challenge of setting the standards, those we should aspire to and the courage to influence the industry to higher goals of a safer future.

Jan 1, 2010

By Rudolf E. Greuer

Introduction The Institution of Mining and Metallurgy and the Institution of Mining Engineers organized the Third International Mine Ventilation Congress held in Harrogate, England. Sixty-one papers were presented and about 300 participants registered. About 30% of the participants came from Great Britain, 20% from South Africa, and about 5% each came from Australia, Canada, China, France, US, and West Germany. The remainder of the participants came from 18 other countries. Eleven of the papers presented dealt with methane, three with diesel exhausts, four with dust, four with radioactivity, 18 with heat, and 15 dealt with main and auxiliary ventilation. Six of the papers dealt with mine fires, which is a boundary region between main ventilation and gas concerns. Ventilation Congress proceedings are available. See ME, December 1984, page 1687, New Books page. With CH4 and radioactivity topics, the Australians dominated since they are becoming large coal and uranium producers. With diesel exhausts, the most important problem in highly mechanized mines, the North Americans were prominent. The South Africans, working in 90% SiO2 in their gold deposits, were preeminent in presentations on dust. They also led in topics related to heat, joined by the West Germans whose mines are getting deeper. In main and auxiliary ventilation, Great Britain and West Germany provided the majority of contributions. Methane The large number of methods for the precalculation of CH4 liberation in longwall mining all contain three elements: gas content of the coal, gas emitting zone (or influence zone of face), and degree of gas emission. Determination of the gas content, commonly accomplished by taking coal samples, does not pose much difficulty. But this is not the case with the other two factors. Most existing approaches rely on rock mechanics observations. Some only rely on intuition or speculation. The West German coal mines conducted a large research project between 1977 and 1982, in which gas pressures around longwall faces were measured. Gas pressures and gas contents can be related. Therefore, influence zone and degree of gas emission can be determined simultaneously. The precalculation of CH4 liberation in room-and-pillar mining is simpler. Since foot and hanging walls remain essentially intact, gas pressure distribution and gas flow can be calculated using hydraulics equations. A key to these calculations is permeability. A group of Australian researchers reported that the permeabilities of rock under three dimensional stress differs from rock under destressed conditions. This fact was known, but no systematic observations existed. These were provided. Methane drainage has been practiced for more than 40 years. It is used with great success in longwall operations. Some of the West Germans think that methane drainage from the footwall is neglected. Under certain geological conditions, they claim this is as important as drainage from the hanging wall. A research project was presented in support of this claim. Considerable efforts have existed for more than 10 years to use methane drainage in room-and-pillar mining. A paper described the accomplishments of Consolidation Coal Co. Since coal and rock are not fractured as much as in longwall mining, gas transport takes place by the slow diffusion from micropores into the cleats. Then, it is transported by laminar flow along the cleats until a drainage borehole or the mine workings are reached. Boreholes about 300 m (1000 ft) long can reduce the gas content of a band of coal 100-m (330-ft) wide by 50% in one year. A paper from India described methane drainage from gob areas. A French paper reported that especially high methane concentrations can be drained from gob areas if the face ventilation is descensional. Methane buoyancy and ventilating pressures compensate each other, and little air dilution by leakage takes place. Another French paper described a newly developed gas and air velocity monitoring system making use of a microcomputer. Four papers on methane dealt with gas outbursts. Two Australian contributions described the problems encountered with CH,-CO2 mixtures and the attempts to solve them with drainage boreholes having 10 to 20-kPa (1.5 to 3-psi) suction pressures. A Hungarian paper described problems and attempts to reduce the risks of gas outbursts in Hungary. Prediction of gas outbursts in coal seams was the focus of an English paper. Observations show that they are frequent when coal, through its geological past, has become soft and brittle with a resulting increased desorption rate. An instrument for gravimetric de-

Jan 1, 1985

By T. Naarttijärvi

The Fabian ore body near Malmberget, Sweden, has an ore reserve of 5 Mt of predominately low grade iron ore, containing 40-55% Fe. Mining began in 1971 with a new method called slot block caving. About 2 Mt were mined, but poor fragmentation resulted in too much secondary blasting. This decreased mucking efficiency to such an extent that the method was abandoned after only 40% of the ore volume had been mined. At this stage a large stope (180 x 30 x 100 m) had been excavated. Although the exposed area was quite large, no caving action occurred in the hanging wall or in the ceiling. LKAB decided in 1977 to introduce sublevel stoping using 105-mm-diam holes. This was the first time large diameter holes were used underground in Sweden. The method had been evaluated in collaboration with the University of Luleå (LuH), the Swedish Detonic Research Foundation (SveDeFo), and the Swedish Mining Research Foundation.

Jan 3, 1982

By Tim O’Neil

Many mining companies try to fight their way up from small operator and exploration company to major producer. Not many companies make it. Cambior Inc., formed in 1986, is one company well on its way to making it as a major operating company. In 1993, Cambior surpassed 15.5 t (500,000 oz) of gold production and began operations at its world class Omai gold mine in Guyana. At the same time, the company has embarked on a program of geographic and minerals diversification. Cambior, a Canadian company, now has interests in eight mines, three development projects and more than 100 exploration properties in North and South America. The company’s goal is to derive 70% of its income from gold and 30% from base metals and other minerals. Cambior’s moderate diversification into base metals gives protection against negative gold price fluctuations. It also balances the typically short term gold mines and the longer term base metal mines.

Jan 1, 1994

The sixth annual conference of the Mineral Economics and Management Society (MEMS) was held Feb. 27 through March 1 in Boulder, CO. This year's event was attended by more than 100 academic, industrial, government and other professionals interested in mineral economics and materials management. With about 250 members worldwide, this not-for-profit society seeks to promote scientific and economic analysis of current relevant issues. This year's program was sponsored by Alcan, Bateman Engineering, Cyprus Amax Minerals, J.P Morgan, Knight Piesold LLC and Newmont Gold. The conference's technical program consisted of six sessions. These included "Financial tools for a changing world," "Access to minerals," "Comparing North and South America," "Environmental issues in today's world" and "Transporting minerals." The program was concluded with a panel discussion titled "National minerals policies in Asia." In addition, a student papers session was held, in which students were given the opportunity to compete for a $1,000 award. The following is a brief review of the technical pro¬gram.

Jan 1, 1997