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By W. R. Reed

The National Institute for Occupational Safety and Health (NIOSH) uses light-scattering dust monitors (nephelometers) in its research to develop dust controls to reduce respirable silica dust overexposures in miners. Recently, the model 1500-pDR, an active nephelometer, was introduced by Thermo Scientific. Testing was completed to ensure compatibility with the metal/nonmetal mine dust personal sampling unit (M/NMDPSU). Results of testing demonstrated that gravimetric concentrations measured from the 1500-pDR are comparable to the gravimetric concentrations measured using the M/NMDPSU, without need for correction, under commonly observed dust loading conditions.

Jan 1, 2012

By R. N. Tempel, M. Lengke

Arsenic sulfide [orpiment, realgar, amorphous AsS and As2S3] oxidation rates were measured in mixed flow reactors at pH~2 and temperature of 25-30oC. The measured oxidation rates for arsenic sulfide solids by dissolved oxygen are in the range of 10-11 to 10-10 mole m-2 s-1 after being normalized to final surface area. The order of arsenic sulfide oxidation rates decreases at pH~2 from amorphous AsS > realgar > orpiment > amorphous As2S3. In comparison to pyrite, arsenic sulfide oxidation rates are approximately 1.5 to 15 times slower than pyrite oxidation rates at pH~2.

Jan 1, 2002

If one can embrace the medical analogue, much of the mining industry currently suffers from a massive bacterial infection. When pyrite-bearing or sulfide-bearing rock formations, tailings, or mine wastes are infected by Acidithiobacillus ferro-oxidans, the likelihood of forming acid rock drainage (ARD) is almost guaranteed. The ?pharmacy? of antibiotics available is extensive, ranging from solid alkaline amendments like limestone to liquid ?medicines? such as sodium lauryl sulfate, sodium thiocyanate, waste milk, and bipolar lipids. Unfortunately, the ?geo-medical? teams of geochemists, microbiologists, engineers, and mine managers lack the tools to surgically apply these active ingredients where they are needed most with a minimum of waste. Distribution of fine grained limestone on the surface of an acidic mine waste dump is analogous to applying a bandage soaked in antacid to treat an upset stomach. The implementation of up-to-date best management practices has not healed the patient; an equivalent combination of hypodermic needle, cyber knife, and arthroscopic probe is clearly needed. Using an engineered, flow-able or pumpable foam or pHoam? as the medicinally analogous ?dextrose delivery solution? for solid and/or liquid ?geo-antibiotics?, the authors have combined off-the-shelf technologies that have been previously applied in solving geotechnical problems in the mining industry. A patent for the innovative process is pending. This paper discusses method concepts and the advantages it could provide over conventional BMPs.

Jan 1, 2012

De Beers? Finsch diamond mine began operation in the 1960s as a surface project using the latest technology available. During the 1990s, the operation, located about 160 km (100 miles) west of Kimberley, South Africa, began its move as an underground mine. The earlier stages (Blocks 1, 2 and 3) of underground work at Finsch used open stope mining methods, also using the latest in technology. The mine began developing Block 4 in 2004. How-ever, studies on this level showed that block caving was a more efficient mining method than open stoping. It was during those studies that De Beers determined that Block 4 would be a good candidate for testing Sandvik?s automated truck haulage technology.

Jan 1, 2008

By I. Demers

Doyon mine, Quebec, Canada evaluates the possibility of desulphurizing their tailings to produce material to be used in as cover over the acid generating tailings disposal site. Laboratory tests were conducted and showed that a single-layer cover made of desulphurized tailings placed over reactive tailings can prevent the generation of acid mine drainage. Modelling with the software Vadose/W was undertaken to optimize the design parameters, namely cover thickness, water table position, and residual sulphide content of desulphurized tailings following laboratory work. It was found that the optimal configuration includes a 1 m desulphurized tailings cover containing 0.8%S, with the water table kept at the interface between the reactive tailings and the cover. To maintain the cover performance to reduce oxygen flux towards acid-generating tailings even in the event of a long dry period, a sand layer is suggested to protect the cover from excessive evaporation. It is possible to reach the environmental objective chosen for Doyon mine (10 mol/m2/year) with the protective sand layer, even in extremely dry conditions.

Jan 1, 2008

By S. C. Chelgani

The Thor lake deposit is a world class resource of rare earth (REE) metals and minerals in Canada. Development work to optimize a REE mineral recovery process flow sheet is underway, however, given the ore mineralogy; the developed reagent scheme is relatively complex. As part of a research project, micro flotation tests were conducted on a feed sample in order to examine factors affecting stream partitioning. SEM-EDX was performed to evaluate variability in grain composition between streams (concentrate and tails) and TOF-SIMS surface analysis was used to determine statistically significant differences in surface species particularly related to potential activation (or depression) of the examined mineral phases. SEM-EDX analysis reveal that the concentrate has a significantly higher proportion of REE bearing grains (carbonates and phosphates) relative to the tail (almost none were identified). Spectral fingerprinting by TOF-SIMS has allowed for the identification of all reagent species investigated. Reagent signal intensity discrimination on test stream mineral surfaces was observed by the TOF-SIMS analysis using reagents at plant concentration levels. TOF-SIMS analysis confirmed that REE bearing grains reporting to the concentrate are doing so in response to collector attachment whereas grains reporting to the tail are doing so in response to a lack of collector and/or in combination with the presence of the depressant. The surface analysis of gangue phases reveal a similar reagent discrimination; the signal intensity of collector species was significantly higher on the concentrate samples relative to the tails while depressant species were significantly enriched on the surface of the gangue phases in the tail samples. A detailed evaluation of the surface species representing the various reagents used in flotation scheme revealed a distinct competitive relationship between two of the reagents. The surface analysis identified that when used in concurrently, there appears to be a negative feedback resulting in a significant reduction in loading for several of the collectors on grains reporting to the concentrate. An evaluation of the effect of reagents on REE mineral in pilot plant is currently under way. Key words: Rare earth minerals, Flotation, Surface chemistry, TOF-SIMS, SEM-EDX

Feb 27, 2013

By S. F. Diehl

Weathered mine waste consists of oxidized primary minerals and chemically unstable secondary phases that can be sources of readily soluble metals and acid rock drainage. Elevated concentrations of metals such as Cd, Cu, Fe, Mn, Ni, Pb, and Zn are observed in deionized water-based leachate solutions derived from complex sedex and Cu-Pb-Zn mine wastes. Leachate (USGS FLT) from the Elizabeth mine, a massive sulfide deposit, has a pH of 3.4 and high concentrations of Al (16700 ug/L), Cu (440 ug/L), and Zn (8620 ug/L). Leachate from the sedex Faro mine has a pH of 3.5 and high concentrations of Al (2040 ug/L), Cu (1930 ug/L), Pb (2080 ug/L), and Zn (52900 ug/L). In contrast, higher-pH leachates produced from tailings of polymetallic vein deposits have order of magnitude lower metal concentrations. These data indicate that highly soluble secondary mineral phases exist at the surface of waste material where the samples were collected. Sulfide minerals from all sites exhibit differential degrees of weathering, from dissolution etched grain rims, to rinds of secondary minerals, to skeletal remnants. These microscale mineral-dissolution textures enhance weathering and metal leachability of waste material. Besides the formation of secondary minerals, sulfide grains from dried tailings samples may be coated by amorphous Fe-Al-Si minerals that also adsorb metals such as Cu, Ni, and Zn.

Jan 1, 2011

By Gordon B. French, Donald E. Garrett

INTRODUCTION Crude oil reserves in the United States are still very large, even though for many years they have not been sufficient to supply our entire domestic requirements. They are continuously being depleted as oil is pumped from the ground, but new discoveries and improved secondary and tertiary recovery methods are helping to reduce the rate of depletion. It is thus a slowly diminishing resource, but even as it is being consumed, immense reserves of oil are left behind as the so called "un-recoverable" portion of petroleum formations. Most oil fields can only obtain a 15 to 40% recovery of the original reservoir, and it is widely quoted that there are still about 300 billion barrels of this un-recoverable oil still in place (Mauch, 1980, etc.). With the present comparatively high oil prices, and the possibility of even higher future prices and short supply, this oil becomes an interesting potential reserve. Mining the petroleum formation would be one means of recovering at least a portion of this oil. The concept of oil mining is neither new nor limited to conventional oil fields, since the procedure could be equally employed with the otherwise difficult to produce heavy oil deposits, and the solid or semi-solid tar sands and diatomaceous hydrocarbon formations. Estimates place the U.S. tar sand resource at about 30 billion barrels, and heavy oil at 5-10 billion barrels (Unitar, 1982). Figure 1 graphically summarizes the heavy oil reserves based upon formation depth and characteristics, while Figure 2 shows their location. It is apparent that the preponderance of reserves are in California and Texas, but that they also occur in many other states. The major companies engaged in oil recovery from the heavy

Jan 1, 1983

By C. Hosten, K. V. S. Sastry, D. J. Kawulok-Englund

Introduction Since the last decade the iron ore processing industry has undergone drastic changes from supplying screened and natural ores to manufacturing tailored concentrates and pellets. Increased need for the beneficiation of lower grade iron ore deposits and the increased demand for higher grade concentrates necessitate finer grinding of iron ores before concentration. The normal filtration stations used in the past are experiencing difficulties in dewatering the finely ground concentrates to moisture levels acceptable for balling. In addition to finer grinding, applications of complex beneficiation techniques has decreased the filterability of the concentrates and create problems in filtration of iron ore concentrates. An overview of the filtration literature indicates there are few research reports on the dewatering of iron ore concentrate slurries. There exists a need to understand the principles and mechanisms involved in the filtration of iron ore concentrate slurries with a goal of developing more efficient filtration techniques. This paper presents the results from the first phase of our research program that included the development of a reproducible benchscale filtration technique and the investigation of the filtration behavior of eight iron ore concentrates.

Jan 10, 1983

By A. K. Mukherjee

The roles of pulsating mechanisms such as the amplitude and frequency of the jig cycle are well established in jigging. Also well established are the roles of the size ratio and the volume fraction of the feed. In iron ore beneficiation plants, these process parameters are optimized to achieve the highest efficiency. However, the role of one of the more important feed characteristics, the liberation characteristic of the feed, has not been studied in detail. Evaluation of the liberation characteristics is difficult because the required washability test is not viable for iron ore feed. In this paper, a new method is proposed in which the liberation characteristics are measured through a separation efficiency value. In the new evaluation method, jigging parameters such as amplitude and frequency of the jig cycle are optimized from the fundamental understanding of the process dynamics and feed characteristics such as size distribution. Then, feeds with different liberation characteristics are tested to evaluate the liberation characteristics of feed in jigging.

Jan 1, 2008

Using mines in Canada, Boart Longyear, a leading provider of drilling services and products, has put its Stage 3 Coring Bit to the test and each time the bit has passed the test with great success. After more than a year in the field at a major mine operation in Sudbury, Canada, the Stage3 coring bit broke life records to become recognized as the most productive design in the industry. In addition to the proven advantage seen in regular bit life increases of as much as 300 percent in some cases, the design is quickly being recognized for its cost-saving operational impact. In Sudbury, the mine operation realized actual cash savings of more than C$45,000 within an eight-month period by making the switch to Stage3 bits. For years, the Sudbury Basin team has relied on the Alpha Extended Crown bit with the Express Waterway geometry option, ordering approximately 500 units per year. This 07 COM ECEX configuration performed well in medium-hard, non-abrasive to ultra-hard, non-abrasive formations with an average bit life of 150 m (490 ft). While satisfied with the performance of the Alpha Ex-tended Crown, the team agreed to put the new Alpha Stage3 to the test. Boart Longyear?s field engineers supplied five drill sites with Alpha Stage3 bits in a 07 COM configuration. After thoroughly testing the Stage3, the results were clear. Even with the well-known performance and versatility offered by the previously preferred configuration, the Stage3 set a new standard of bit performance. The new bit maintained its cutting edge for up to three times longer than the Alpha Extended Crown, a significant performance increase when compared to the 07 COM ECEX.

Jan 1, 2009

By B. J. Schat, A. W. O. Bots, O. S. Langhorst

Amsterdam City Council is building a new metro line, the North–South Line. The line passes under Amsterdam Central Station (a listed building) about 18m below street level. The retaining wall that has to be built underneath the existing building is an innovative construction consisting of two rows of steel piles interspersed with a solid mass of overlapping jet grout columns: a composite ‘sandwich’ wall. This paper gives an overview of the approach taken to designing (computational models) and building the retaining wall. Special attention is paid to the observational method used for the construction of the jet grout columns.

Jan 1, 2007

When defining a ?megaproject,? one need only to look at Seattle, WA?s State Route 99 Alaskan Way Viaduct replacement project. This $3.1-billion project is one of the largest of its kind in the world, and includes the use of the world?s largest tunnel boring machine (TBM). However, for as large as the Alaskan Way project is ? especially given the size of the TBM being used ? there are several other megaprojects underway around the world. Each has its own challenges that require innovative design techniques and financing arrangements, as well as variations on established tunneling technologies. So it was that 266 tunneling and underground construction professionals ? owners, contractors and engineers ? convened in Seattle in November for the Cutting Edge Conference on Megaprojects. This was the second joint meeting between the Underground Construction Association of SME and the North American Tunneling Journal. The first joint conference took place in April 2012 in Miami, FL and attracted 238 attendees. A third joint conference, to be held in 2014, is in the planning stage. The key reason Seattle was chosen as the site of the megaprojects conference is the Alaskan Way Viaduct project. Before the conference began, many of the attendees were able to visit the project and get a close look at Bertha, the Hitachi Zosen earth pressure balance TBM that is boring the tunnel. In addition, the conference included an exhibit that attracted 20 industry suppliers, up from 10 the previous year in Miami. The 25 presentations during the two-day conference covered all aspects of the tunneling and underground construction of megaprojects. Topics included the Alaskan Way Viaduct project; considerations for procurement and contracting; political risk, financing and insurance; international megaprojects; risk and risk sharing and project delivery. Each session concluded with panel discussions.

Dec 1, 2013

By F. -J. Wodopia

Sustainability of energy supplies has been an issue of general interest for a long time. Whilst in the past the continuous productive use of natural commodities was in the fore, its compatibility with the environment and climate and ultimately also social aspects have recently gained more and more attention. Today many discussions focus on the climate compatibility of individual options to act. Fossil fuels, in particular coal and lignite, are generally challenged because coal use makes a significant contribution to global man-made CO2 emissions. The drastic increase in the consumption of fossil fuels is not explained by the fact that coal utilisation technologies are not or cannot be sustainable but rather by the growing world population and the endeavours numerous national economies trying to catch up economically. Coal is the world’s No. 1 fuel and, in the view of many experts, will keep this position also in the foreseeable future. The access to its deposits plays a significant role for the economies of the emerging countries. Consequently the aspects of energy security and economic efficiency need to be considered at eye level with climate compatibility. In Germany, however, the public acceptance of fossil fuels and of large industrial projects is in the focus of attention.

Jan 1, 2011

By D. Brady

The need for onsite gas monitoring during, or following, a major incident at an underground coal mine has long been recognised. Recommendations from inquiries following Queensland mine disasters have included ?qualified persons and equipment for rapid analysis of gas samples be available in times of emergency? and that ?this may be accomplished by either mobile laboratories or laboratories established in each mining locality.? Following the Moura No. 2 disaster, the Queensland Government allocated funds to Simtars for a mobile laboratory to respond should such a disaster occur again in the future. This vehicle was commissioned in 1997 and has been used at many mine sites under a wide range of scenarios. Simtars, armed with over ten years of operational experience with this mobile laboratory, has taken an active role in the design and construction of a modernised replacement unit. With a twenty point tube bundle system and ultrafast gas chromatograph the result is, arguably, the best equipped mobile gas analysis laboratory for mine emergency response in the world. This paper outlines the features of the new laboratory, its capabilities and the philosophy behind the design and inclusions.

Jan 1, 2012

By J. A. Delgadillo

Computer simulation and mineral modeling was applied to the optimization of a grinding circuit in a plant processing 256 t/h magnetite. These tools were used to develop a grinding and classification configuration to decrease the grade of silica in the magnetite concentrate, which is produced by the plant. Empirical grinding and classification models were finely tuned using plant experimental data. The JKSimMetTM 5.0 software was used to simulate the grinding and classification units. By applying changes in the original circuit, a throughput increment of 100% was achieved with an important reduction in the energy consumption. The silica content in the magnetite concentrate can be decreased by regrinding the coarse fraction of fine screens into a separate ultrafine grinding unit instead of returning this flow to the ball grinding mills.

Jan 1, 2008

By M. Gangal

CANMET-MMSL, in cooperation with Dry Systems Technologies and Quinsam Mine, conducted a study to determine the effects of B50 biodiesel on the emissions of a flameproof diesel power package in comparison with mining diesel fuel for application in underground coal mines. The emissions testing for coal mine application requires that the intake air mixture to the engine should be at 1.25 percent methane by volume in air. The tested power package system included a naturally aspirated, mechanically-controlled diesel engine with a diesel oxidation catalyst (DOC), a heat exchanger, flame arresters, and a low temperature disposable diesel particulate filter. The engine dynamometer tests were conducted at the CANMET-MMSL Diesel Emissions Research Laboratory in Ottawa using the ISO 8178-C1 test protocol. The separate and combined effects of a B50 biodiesel blended fuel, and with and without 1.25% methane enriched intake air were measured on a diesel power package. Fuelling the baseline engine (without methane), with B50 biodiesel blend reduced carbon monoxide (CO) by 44%, and increased nitrogen dioxide (NO2) by 19%, and particulate matter by 31% relative to the mining diesel fuel. Similarly, injection of 1.25% methane to the intake air for baseline engine with mining diesel fuel increased engine power by 15%, CO by 124%, and NO by 15%, and decreased NO2 by 13%. The effect of B50 biodiesel relative to the mining diesel for coal mines application (with methane for both fuels) was to reduce CO by 27%, and NO by 6%, and increase NO2 by 23%, with no change in engine power. The overall results indicate that the minimum ventilation rate for the equipment application in coal mines with B50 biodiesel was 4.11 m3/s (8,700 cfm), slightly higher than the ventilation rate of 4.01 m3/s (8,500 cfm) with the mining diesel fuel. This slight increase in ventilation rate for B50 biodiesel fuel was due to an increase in NO2 at one of the operating test points, and the ventilation rate for this equipment was governed by NO2 in the exhaust gas.

Jan 1, 2009

By B. Asbury, M. Cigla, C. Balci

The Western Mining Resource Center (WMRC) at the Colorado School of Mines (CSM) received a grant from the National Institute for Occupational Safety and Health (NIOSH) to perform a study that will help reduce the amount of respirable dust generated from the cutting of coal. The study is based upon laboratory testing and field experience. This information is being used to develop a new cutterhead design in conjunction with Joy Mining Machinery. The new cutterhead design is being evaluated with existing computer models developed at CSM. The new continuous miner cutterhead will be tested at the Twenty Mile Coal Company’s Foidal Creek Mine. Baseline testing with the current cutterhead will also be performed. This paper presents laboratory test results, design methodology, and test results performed to date.

Jan 1, 2002

By R. G. Benson, P. R. Wotruba, K. W. Schmidt

Introduction The Fortitude deposit is located in Nevada's Battle Mountain mining district in the central Great Basin region of the Basin and Range province of the western US. The deposit is at Copper Canyon in the southernmost portion of the district, about 19 km (12 miles) southwest of Battle Mountain (Fig. 1). Mining activity in the district began in 1866 (Roberts and Arnold, 1965). Base and precious metals were mined by underground methods intermittently until 1955. Placer gold was first discovered at Copper Canyon in 1912. Moderate scale dredging of alluvial gravel at the mouth of Copper Canyon was conducted by the Natomas Co. from 1944 to 1955 (Johnson, 1973). In 1967, Duval Corp. began large scale open-pit copper mining. (Sayers, Tippett, and Fields, 1968). Copper prices decreased and precious metals prices increased in the mid-1970s so Duval's exploration efforts at Copper Canyon shifted to precious metals. These exploration efforts resulted in the discovery of the Tomboy-Minnie deposits and shortly afterward, the Northeast Extension deposit at Copper Canyon (Blake, Wotruba, and Theodore, 1984; Fig. 2). The Fortitude deposit was discovered in late 1980, after Duval had proceeded with precious metals production at Copper Canyon. Converting the existing plant facilities at Copper Canyon to a precious metals recovery system was completed in 1978 (Jackson, 1982). Production from the Tomboy-Minnie deposits began in early 1979. Precious metals production moved to the Northeast Extension deposit in 1982. In late 1984, after three years of preproduction stripping and mining of the Upper Fortitude ore zone, production from the higher grade Lower Fortitude ore zone began. Currently, Battle Mountain Gold Co. operates the Fortitude deposit. Production from the Battle Mountain mining district before 1967 included 4.6 t (150,000 oz) of gold, 65.3 t (2.1 million oz) of silver, 13.6 kt (15,000 st) of copper, 4.5 kt (5,000 st) of lead, and 13.6 kt (15,000 st) of zinc (Roberts and Arnold, 1965). At the time of Duval's 1967 start-up, ore reserves at Copper Canyon included 12.6 Mt (14 million st) in the East ore body and another 3.6 Mt (4 million st) in the West ore body. Both had average grades of 0.79% copper, 16.1 g/t (0.47 oz per st) silver and 0.86 g/t (0.025 oz per st) gold (Blake et al., 1984). The Tomboy-Minnie deposits collectively contained 3.5 Mt (3.9 million st) of ore grading 3.09 g/t (0.09 oz per st) gold and 9.6 g/t (0.28 oz per st) silver. The Northeast Extension reserves were identified as 1.4 Mt (1.5 million st) of ore with an average grade of 2.9 g/t (0.085 oz per st) gold and 5.1 g/t (0.15 oz per st) silver. Initial total reserve estimates for the Fortitude deposit were 14.5 Mt (16 million st) grading 5.14 g/t (0.15 oz per st) gold and 29.8 g/t (0.87 oz per st) silver (Jackson, 1982). Therefore, before large scale mining, the Copper Canyon area contained a minimum of 102.6 t (3.3 million oz) of gold and 541 t (17.4 million oz) of silver as mineable reserves. The Fortitude deposit reserves as of Jan. 1, 1985 were 10.6 Mt (11 million st) grading at 5.28 g/t (0.154 oz per st) gold and 28.5 g/t (0.83 oz per st) silver. Currently, the company is producing 6.8 t (220,000 oz) of gold and significant amounts of

Jan 7, 1986

By A. Noble, R. Q. Honaker, J. Werner

Recovery of rare earth elements (REE) from coal-related resources has recently received significant interest due to supply concerns and their key roles in critical industries and defense-related technologies. An integrated flowsheet consisting of sorting, crushing/grinding, physical separation, acid leaching, solvent extraction, and selective precipitation was designed to achieve continuous production of rare earth products from various coal-related resources such as coarse refuse and acid mine drainage. A pilot plant was constructed that enabled continuous testing of the circuitry on a range of different coal-based feedstocks. Despite achieving significant success in producing high-grade rare earth oxide products, low REE recovery values and high operational costs necessitated a re-evaluation of the process flowsheet. This article describes the circuitry improvements that were based on both laboratory and pilot plant test results. Roasting as a pre-leach treatment was found to significantly improve the leaching rate and overall REE recovery values. After roasting West Kentucky No. 13 and Fire Clay coal refuse materials at 600 °C, REE recovery increased by 60 and 40 absolute percentage points, respectively. Rare earth concentration in the pregnant leachate solution (PLS) was increased to around 700 ppm prior to solvent extraction using a staged precipitation method. REEs in the precipitate were re-dissolved, purified, and extracted from the PLS using solvent extraction and selective precipitation to values of around 80%. As a result of the improvements, chemical consumption in the acid leaching and solvent extraction processes was significantly reduced. A techno-economical assessment of the improved flowsheet indicated significant commercialization potential.