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By F. Habashi

The changes that took place in China between 1984 and 2004 are remarkable. Visits were made to universities, research institutes, metallurgical industry, and many cultural centers within five trips during this twenty years period. The impressions of these visits are outlined.

Jan 1, 2007

By John J. Murray, Michael T. McRae, Michael A. Krulc, Kathy L. Schuler

The San Vicente Pipeline Tunnel Project involves the construction of an 8.5-foot-diameter water pipeline in an 11 mile tunnel in San Diego, California. The tunnel is located in extremely variable geologic conditions of strong granitic and volcanic rocks, weak sedimentary rocks, abrasive conglomerates, and mixed face conditions. One reach of the tunnel is a 5,200-foot mixed face reach that includes Friars Formation Conglomerate overlying granitic rock. Due to the variable ground conditions in this reach, the use of a TBM was deemed too risky and the contract documents required drill-and-blast and hand mining methods. Although it was not required, the contractor elected to construct this reach using NATM methods. This paper describes the geology of the 5,200-foot mixed-face reach, the design evaluation, and the construction challenges faced on this project.

Jan 1, 2007

By R. Curtis

To achieve compliance with 2015 EPA Tier 4 Final regulations, which permit only around 10% of Tier 3 particulate matter (PM) and NOx emissions, a number of technologies are being implemented. Use of a fuel borne nanoparticle combustion catalyst reduces the level of PM and unburned hydrocarbons exiting the combustion chamber, alleviating the burden on downstream exhaust after-treatment systems. The impact of an iron-ceria combustion catalyst (GO2) on carbon oxidation kinetics and on diesel engine emissions is presented. The iron-ceria nanoparticles catalyze carbon oxidation at lower temperatures and increase the oxidation rate by a factor of 18 at 400 °C. Engine tests on a generator powered by a John Deere Model engine and field tests on a Cummins ISC 330 tractor truck and CAT 3508B propulsion engines are presented. Use of GO2 resulted in a reduction in PM10 (particulate matter under 10 um) emissions of up to 26% and a hydrocarbon emission reduction of up to 41%. NOx emissions did not increase in these trials and the amount of change depended on engine type. Application of this fuel borne technology for emissions reductions in mining equipment offers significant benefits.

Feb 27, 2013

By S. M. Flaherty, R. E. Scheffel, A. Guzman

Geochemical conditions within a leaching operation are heterogeneous. This variability arises mainly from hydrological controls imparted by physical characteristics of the ore and by heterogeneous metallurgical properties at the rock-fragment and industrial heap scale. The resulting chemical conditions are responsible for stratified mineral recovery, non-uniform extraction and prolonged leach cycles. This paper presents field data from a sulfide-leaching operation which clearly demonstrate the impact of chemical heterogeneity on metal recovery and the potential use of modern measuring techniques to facilitate operational monitoring and decision making for optimization of leaching operations.

Jan 1, 2006

By S. Vivek

An atomic force microscope (AFM) was used to measure the surface forces between silica surfaces immersed in solutions of hydrolysable cations and/or sodium oleate. Hydrophobic forces were observed at the pH range where the concentration of the singly-charged hydroxo-complexes (CaOH+ or MgOH+) in solution is the highest. In the absence of oleate, the adsorption of the hydroxo-complexes was indicated by the disappearance of the repulsive hydration force. These results suggest that the hydrolysable cations adsorb on silica as singly-charged hydroxo-complexes. Based on the results obtained in the present work, a model for the adsorption of hydrolysable cations has been developed.

Jan 1, 2009

From the massive equipment that moves the earth, to the parts that keep the equipment moving, it was all on display for more than 35,000 people who at-tended MinExpo 2008 at the Las Vegas Convention Center Sept. 22-24. In the largest show in the illustrious history of MinExpo, the success of the recent commodity boom was reflected in the more than 55,700 hm2 (600,000 sq ft) of floor space that was jam-packed with nearly 1,300 vendors. Among them, the makers of the industry?s largest machines, displaying their latest and greatest trucks, shovels, excavators, drills and other mining equipment. During the nearly decade-long commodities boom, equipment makers have worked hard to keep up with demand while also investing heavily in research and development. The beneficiaries of this R&D is the end user who saw first-hand at MinExpo 2008 the many advances that have already been made in safety, comfort and productivity from all the manufacturers. R&D has also helped spark more talk of automation, which is being used already at some of the world?s largest mines. Caterpillar and Komatsu have worked with the technology in surface mining and Bucyrus and Sandvik are among the industry leaders applying the science of automation to underground mines. Technology has in-creased greatly since the idea of moving massive equipment remotely was first knocked around and the idea of entire fleets operating around the clock seems to be getting closer to reality. But, until that happens, MinExpo attendees were treated to a show that featured some of the most impressive current machines the industry has to offer. In the largest booth space of the convention, Caterpillar (www.cat.com) displayed the culmination of an ambitious $280-million dollar investment, with the introduction of its new mining fleet of four new trucks. The F-series was un-veiled with common features in safety, cabs, engines, frames and bodies and Tier 2 compliant engines. The F series also features a return to the electric drive option. ?When our customers asked us for improvements to our mining trucks, we responded by making a record investment in every single truck in our line, as well as the increased capacity to produce more of them,? said Cater-pillar group president Stu Levenick. ?New technologies have allowed us to make trucks more reliable, easier to maintain and more friendly to the operator and to the environment.? The 793-series is in the 218- to 227-t (240- to 250-st) class that will be available in both mechanical (793F) and electric (793F ac) versions. The electric drive-only 313- t (345-st) 795F was also introduced, while the flagship 797B truck is in the process of being replaced by the new 797F mechanical drive, maintaining its 345- to 363-t (380- to 400-st) target payload. Completing Caterpillar?s new mining truck line will be new versions of the 785 and 789 mechanical drive trucks. The next generation of trucks will be phased into production during the next two years, with the Cat ac drive models expected to go into production in late 2010. The $280-million in-vestment is Caterpillar?s largest commitment ever to the mining industry

Jan 1, 2008

By H. Hejny

"The mine of the future will exploit mineral raw materials at greater depths than today, requiring completely different approaches compared to today’s deep mines, in order to get mineral rights. Only these eco-efficient mines will contribute to improved access to domestic mineral resources, secure the sustainable supply of mineral raw materials for Europe and reduce the import dependency. IntelliMine will contribute to realise these concepts of invisible, zero-impact and safe mines. The mine of tomorrow will run an integrated concept in order to guarantee the desired level of sustainability. All operations necessary for the eco-efficient provision of the minerals including waste management will be carried out underground. This will drastically reduce the volumes being transported, minimising above ground installations and thus the environmental impact. IntelliMine will develop necessary innovative methods, technologies, machines and equipment for the safe, eco-innovative, intelligent and economic exploitation of mineral raw materials in the EU, especially at greater depths."

Jan 1, 2011

By Douglas R. Cook

Exploration record In preparing this paper, a list of world class discoveries prepared in 1983 has been updated. In both surveys, the following criteria were used in the definition of world class discoveries: • deposits that are continuously operated and consistently return a profit even in periods of low metal prices; • deposits large enough to significantly affect a medium sized corporation's profits; and • these deposits should be in the lower one-third cost per unit of metal produced for all similar deposits. Only 70 discoveries in the last 40 years qualified as world class deposits using these criteria. Unfortunately, this restricted population was too low to develop meaningful trends. The numbers were therefore enlarged to include all significant discoveries. The principal feature of a significant discovery is that its size and grade would yield more than $500 million in revenue using average metal prices for the last five years. A significant deposit should also meet some of the standards for a world class deposit. A tabulation of these deposits are shown in Table 1. The number of discoveries increased to 166 from 70 using the revised classification. The relationship between the number of discoveries per year and their location by continents was prepared from these data. Figure 1 shows the number of discoveries per year for the nonCommunist world. It also shows estimated and actual nonCommunist world exploration expenditures per year and the commodity price index. These data show that modern exploration started in the late 1940s, with the tempo picking up rapidly in the 1950s. The maximum discovery rate occurred in 1962. Thereafter, the discovery rate gradually declined to the present. This occurred despite a real increase in expenditures from about $200 million/a in 1955 (1982 constant dollars) to more than $900 million/a in 1980. Thus, these data suggest a significant decrease in the exploration success ratio (total exploration expenditures a year divided by the number of significant discoveries) in the last 20 years. As an example, $70 million was spent for each significant discovery in the early 1960s as compared with $225 million in the late 1970s (expressed in 1982 constant dollars). However, with the general declining trend of discoveries, one can perceive a more pronounced drop in 1973 and then a sudden increase in 1974, 1975, and 1976. This increase is probably related to the inflation of the 1970s that in turn created an environment for the explosion of commodity prices, as shown by the commodity price index on Fig. 1. Thereafter, the decline in discoveries resumed in 1975 until the present. Exploration performance by regions North American discoveries are shown in Fig. 2. The graph shows three pronounced high discovery peaks in 1962, 1975, and 1980-81.

Jan 2, 1986

By Michael J. Lehnen

Slurry diaphragm walls are commonly used as both temporary excavation support walls, and permanent structural walls, for circular shafts and long rectangular structures (such as underground subway stations); however, they are not commonly used for more compact rectangular or square shafts. In these instances, a second wall is typically cast inside the slurry walls to form the permanent structure. This paper discusses the approach used on the Silicon Valley Rapid Transit Project in California to analyze these compact rectangular types of structures for static and seismic loading, and to determine whether or not slurry walls can be confidently used as both the temporary and permanent walls for two tunnel ventilation shafts.

By Douglas Beahm

Energy Metals Corp. (EMC) holds numerous mineral properties in the northern portion of the Great Divide Basin. The JAB property is one of several potential properties being planned for development as a satellite facility to the greater Antelope uranium project. A National Instrument 43-101 Technical Report was completed for the JAB property. This report estimated total measured and indicated mineral resources on the property totaling 1.6 kt (3,555,022 lbs) U3O8 contained in 2.2 Mt (2.4 million st) at an average grade of 0.073 percent U3O8 at a 0.25 grade times thickness (GT) cutoff in accordance with CIM Standards on Mineral Resources and Reserves. The JAB property is located in Sections 13, 14, 15, 16, 21, 22 and 23, Township 26 North, Range 94 West, approximately Latitude 42° 14’ North and Longitude 108° 00’ West (Fig. 1). This property consists of unpatented mining lode claims and Wyoming state mineral leases com-prising approximately 850 hm2 (2,100 acres).

Jan 1, 2007

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 Paloma Lazaro, Moe Momayez

Heat-related illnesses (HRI) are relatively common in both hot surface and underground mining operations. When workers are exposed to extreme heat or strenuous work in a hot environment, they become prone to heat stress. Heat strain is the result of the body’s response to external and internal heat stress. It is therefore vital for the conditions leading to heat strain be detected and treated in a timely manner. Heat-related illnesses are manifested by exhaustion and heat stroke. The predicted heat strain (PHS) [ISO 7933 (2004)] model has been developed to predict the health condition of the worker in terms of core body temperature and water loss. The PHS model tested in this study is based on eight physical parameters that are measured at different intervals during a work shift. They include air temperature, humidity, radiation, air velocity, metabolic rate, clothing insulation, posture, and acclimatization. The model predictions are then compared with a direct physiological measurement, such as core body temperature. We present the results of an extensive study that monitored and predicted body’s response to heat stress under different environmental and working conditions. The PHS model provided reliable results in most instances in comparison with other prediction methods currently in use in the field.

By Paloma Lazaro, Moe Momayez

Heat-related illnesses (HRI) are relatively common in both hot surface and underground mining operations. When workers are exposed to extreme heat or strenuous work in a hot environment, they become prone to heat stress. Heat strain is the result of the body’s response to external and internal heat stress. It is therefore vital for the conditions leading to heat strain be detected and treated in a timely manner. Heat-related illnesses are manifested by exhaustion and heat stroke. The predicted heat strain (PHS) [ISO 7933 (2004)] model has been developed to predict the health condition of the worker in terms of core body temperature and water loss. The PHS model tested in this study is based on eight physical parameters that are measured at different intervals during a work shift. They include air temperature, humidity, radiation, air velocity, metabolic rate, clothing insulation, posture, and acclimatization. The model predictions are then compared with a direct physiological measurement, such as core body temperature. We present the results of an extensive study that monitored and predicted body’s response to heat stress under different environmental and working conditions. The PHS model provided reliable results in most instances in comparison with other prediction methods currently in use in the field.

By O. Ogunsola, M. Downing

This paper gives a brief overview of impacts of coal blending on coal-fired power plants performance and discuses the preliminary results of an on-going study aimed at evaluating the effect of coal properties on the effectiveness, compatibility and thermal reactivity of coal blends. Plant survey studies reported no significant impacts on an existing plant designed for a high rank coal when switched to a blend of low- and high- rank coal. However, slight modification of some aspects (handling, fuel storage/stockpile, transportation, preparation, and general housekeeping) of plant design and operation may be necessary. The preliminary results of an on-going study at the Mineral Industry Research Laboratory shows that more compatible and better blends could be made from coals where ranks are closer than from those where ranks are far apart.

Feb 24, 1997

By Georgene Renner, William R. Yernberg, William Gleason

American Commercial (ACI) offers a selection of ground control solutions. Beginning with steel liner plates installed in the Gratiot Avenue sewer system in Detroit, MI 1920, ACI is one of the leading designers and manufacturers of underground steel supports in North America. ACI is also a leader in fire-proofing underground structures with its Promat Fire Protection Boards. The sandwich panels have been used in many new and retrofit tunnel and underground construction projects worldwide. Ease of installation and replacement, cost effectiveness and superior performance have made this product line the premier choice of owners and designers for structural protection, fire-life safety requirements and architectural finish needs.

Jan 1, 2007

By Jacob Carr, Chenming Zhou, Nicholas Damiano, James Noll, Jingcheng Li

Machine-related injuries are one of the major safety concerns in underground coal mines. Severe injuries and fatalities occur when a miner is struck, crushed, or pinned by mining equipment such as a continuous mining machine (CMM), shuttle car, or a scoop. Proximity detection systems (PDSs) have been applied in mining to reduce these types of injuries and fatalities. All of the PDSs that are currently approved by the Mine Safety and Health Administration (MSHA) for use in underground coal mines are magnetic-field based and could be affected by metallic objects such as trailing cables. Researchers from the National Institute for Occupational Safety and Health (NIOSH) investigated the influence of trailing cables on the performance of PDSs. In particular, the magnetic field coupled from proximity system generators to a de-energized trailing cable was characterized. The results show that significant energy can be coupled from the proximity system generators to a trailing cable when there is a closed loop in the cable. The effect on PDS performance from the magnetic field radiated around an energized trailing cable was also quantified for different current amplitudes in the cable. It is shown that the magnetic field caused by the electric current in the trailing cable mainly consists of a 60-Hz signal and its harmonics which causes little interference to the PDS. The results presented in this paper can help PDS manufacturers to design better systems that are more immune to these effects.

By Xuchen Fan, Chenyang Zhou, Yuemin Zhao, Liang Dong, Chenlong Duan

A gas–solid fluidized bed using magnetite particles is an effective methodology for coal beneficiation in the field of dry coal cleaning. Broadening the size range of magnetite used in the bed decreases medium preparation cost. In this study, a tapered fluidized bed was used to investigate a magnetite particle size range of −0.5 + 0.074 mm. The results showed that a tapered fluidized bed effectively strengthens mixing of magnetite with a wide size range (−0.5 + 0.074 mm). The results of beneficiation experiments indicated that with increasing tapered angle, separation efficiency increased and then decreased. The highest separation efficiency was obtained at a tapered angle of 10°. The optimal results showed that the ash content of the concentrate decreased from 31.82% to 12.33% with a probable error of 0.11, which indicated that a tapered fluidized bed was efficient to improve fine coal beneficiation performance.

By P. R. Dugan

Sulfur removal from high sulfur coal has several objectives including: a) reduction of the atmospheric load that contributes to the problem of acid precipitation; b) reduction of ash, which contributes to decreased energy transfer in boilers, as well as ash disposal; and c) alleviation of the social and economic dislocations reluted to uneven geographical distribution of sulfur in coal reserves. Cost in relation to the value of refined coal will govern the development of an emerging coal refining industry. Estimation of the premium paid by power companies for coal with a low sulfur content is a good estimate of the value that will be added as the result of refining. Estimates of premiums paid in 1984 are $28.65/t ($26 per st) for reduction of total sulfur from 3’% to 1% S and greater than $28.65/t ($26 per st) for removal below 1% sulfur.

Jan 8, 1987

By G. S. Austin

The St. Cloud Mining Company extracts clinoptilolite about 6.5 km south of Winston, Sierra County, New Mexico. Production is about 18,000 mt/year. Natural zeolites are good adsorbents for positively charged solutes such as ammonium. St. Cloud’s production is used in animal hygiene, animal feed, environmental mitigation, air and water filtration, and other applications. By a simple chemical treatment with a surfactant, zeolites can also be modified to adsorb negatively charged solutes such as nitrate and arsentate, and neutral organics such as solvents and fuel components. These surfactant-modified zeolites are used in treating groundwater contamination, stormwater runoff, and solvent vapors from painting operations.

Jan 1, 2002

By Hassell E. Hunter

The Wyoming Mineral-Conoco Crownpoint Project represents the first time that big hole drilling has been exclusively used to develop totally a privately financed mine below a depth of 1000 feet. Three shafts, one ten feet in diameter and two six feet in diameter, were successfully drilled to depths of 2243', 2188' and 2188' respectively and cased with hydrostatic designed steel casing. The largest shaft is to be used to handle muck and water from station excavation and enlargement of the other two shafts. A reverse circulation system with potassium chloride base mud was used for drilling. The mud was cleaned by settling in steel lined tanks with assistance by cyclone type separators. Deviation was monitored by gyroscopic surveying at 30 foot intervals and did not exceed 16 inches off plumb. Casing was designed to withstand hydrostatic pressures with a 1.5 safety factor to the large shaft and 1.25 safety factor for the smaller shafts. All casing welds were x-ray tested prior to lowering the casing in the hole. Cementing the annular space completed the operation. The total time to mobilize, drill and move off the three shafts was 363 days. The drilling operation was completed ahead of schedule and under budget.

Jan 1, 1983