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By John F. Gamble

Paper 1?South African experience with asbestos-related environmental mesothelioma: Is fiber type important? Neil White, Gill Nelson, Jill Murray The purpose of this review was to illustrate the importance of the type of asbestos in environmental mesothelioma. South Africa is a logical place to assess fiber type. The three major types of asbestos (crocidolite, amosite and chrysotile) were mined (all asbestos mining stopped in 2002) in South Africa. The association between asbestos and mesothelioma was discovered in South Africa. The occupational literature indicates high mesotheliomagenic potential for crocidolite, less for amosite and less still for chrysotile. Since South Africa has been a major source of crocidolite, relatively high rates of mesothelioma in the mining population is not surprising. High rates of mesothelioma due to environmental exposure is surprising, except perhaps when the authors? point out potential sources for community exposures (e.g., mine tailings used for road surfacing, golf courses, brick and plaster making; insulation in residential ceilings; children playing on fiber-rich waste rock). The authors? reviewed four studies reporting on mesothelioma cases and their sources of exposure and fiber type. Overall 23% of the known cases were attributed to the environmental (not occupational) exposure and about 90% were due to crocidolite asbestos. The proportion of environmental mesothelioma is considerably higher than in Western Australia where crocidolite is also mined. There the overall rate of environmental mesothelioma is about 6% (and less than 1% from residence in a crocidolite mining area).

Jan 1, 2007

By Ryan C. Stephan, Christopher Mark

"Some of the weakest roof in United States coal mines is found in the Illinois Basin. Historically, the Illinois Basin has also suffered from high rates of unplanned roof falls and rock fall injuries. During the past decade, however, roof fall and rock fall injury rates have fallen dramatically, and are now lower than the national average. Several technologies are responsible for the improvement. Roof screen was rarely used ten years ago, but a number of mines now use it on a regular basis to prevent rock falls and rock fall injuries. Other roof skin control fixtures and work practices have contributed as well.The reduction in roof falls is also directly attributed to enhanced intrinsic roof support. Stiffer primary bolting patterns have reduced the magnitude of roof spalling and roof sag. They have also helped create a more intact beam that is able to be suspended from longer cable bolts. Cable bolt design methodology has also contributed to this reduction in roof falls. Some early cable bolt applications were unsuccessful because they employed as few as two cable bolts per intersection. This paper describes a methodology for estimating rock loads for support design.ROOF FALL TRENDS IN THE ILLINOIS BASINAlthough the Illinois Basin has a long history of poor roof conditions and high rates of unplanned roof falls and rock fall injuries, recent data indicates a change in the trend. Roof fall rates are determined by dividing the total number of non-injury roof falls by the total number of hours worked underground. The data is considered for 200,000-man hours. While the Illinois Basin was once a coalfield experiencing roof falls at nearly twice the national average, it is now at or below the national rate. Figure 1 indicates the trend over the past 20 years. In 2008, the Illinois Basin mines experienced 5.06 roof falls every 200,000-man-hours, compared to only 0.75 in 2018.There has also been a significant reduction in the rate of rock fall injuries in the Illinois Basin coal mines, as shown in Figure 2. In 2008 there were 1.48 rock fall injuries every 200,000-man-hours, compared to only 0.43 in 2018.ILLINOIS BASIN COAL ROOF GEOLOGYThe roof rock in the Illinois Basin has been studied in the past to understand the primary causes of roof failures (Molinda et al., 2008; Thompson, 2010; Molinda and Mark, 2010). Rusnak and Mark (2000) evaluated 10,000 laboratory strength tests from 800 rock units and concluded that for shale, siltstone, and sandstone, the strength of the Illinois Basin variety was less than half that of the same rock types in Central Appalachia (Figure 3). A study of Coal Mine Roof Rating (CMRR) measurements in more than 200 US coal mines also found that weak roof was predominant in the Illinois Basin (Mark and Molinda, 2005)."

Jan 1, 2019

Colloidal interactions play a critical role in mineral processing, including grinding, physical separation (particularly flotation), dewatering, and tailings management. Despite great energy input in comminution to liberate valuables from gangues, heterocoagulation between valuables and gangues would prevent the separation of valuables from gangues. On the other hand, selective coagulation/flocculation to increase the size of desired fine particles could enhance physical separation and dewatering, while dispersion is needed for fine grinding. To control the state of colloidal dispersions by creating favorable conditions, it is of paramount importance to study colloidal interactions in a relevant system and understand underlying mechanisms. This review summarizes recent advances in developing the-state-of-the-art techniques and novel methods of measuring colloidal forces, including atomic force microscope, surface force apparatus, zeta potential distribution measurement, quartz crystal microbalance with dissipation, and our recently developed integrated dynamic force apparatus. The basic principle of each technique was introduced first, followed by a summary of critical information derived for the relevant mineral processing systems. Finally, the pros and cons of each technique were discussed to emphasize the use of complementary techniques that assist in solving fundamental problems in mineral processing.

By William M. Gleason

When SME’s 2006 Arizona Conference convened in December at the Hilton El Conquistador Resort in Tucson, AZ, there was considerable excitement among the 387 attendees. There was a noticeable buzz surrounding the progress of Phelps Dodge’s Safford copper mine in southern Arizona, one of the first new major copper mines to be permitted in more than 30 years in the United States. There were also plenty of good feelings about the mining industry in general. Commodity prices remained high and with no signs of a slowdown in the immediate future. Things were good in Arizona. But there were also cautionary tones at the conference and the Mining Foundation of the Southwest banquet that preceded it.

Jan 1, 2007

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

By G. H. Sedahmed, S. A. Nosier, M. H. Abdel-Aziz, A. A. Mubarak, M. A. El-Naggar, E. G. Abdel-Aziz

The performance of a rotating fixed bed reactor in recovering copper from industrial waste solutions by cementation is studied under various conditions. The rotating fixed bed is made of stacked woven steel screens to take advantage of two features of screens: the ability to present large area per unit volume and their ability to promote high turbulence. Variables studied are initial CuSO4 concentration, bed rotation speed, mesh number of the screens and bed thickness. The presence of baffles was found to increase the rate of cementation. The data were correlated by a dimensionless mass transfer correlation suitable for the design and operation of large scale cementation reactors.

By G. H. Sedahmed, S. A. Nosier, M. H. Abdel-Aziz, A. A. Mubarak, M. A. El-Naggar, E. G. Abdel-Aziz

The performance of a rotating fixed bed reactor in recovering copper from industrial waste solutions by cementation is studied under various conditions. The rotating fixed bed is made of stacked woven steel screens to take advantage of two features of screens: the ability to present large area per unit volume and their ability to promote high turbulence. Variables studied are initial CuSO4 concentration, bed rotation speed, mesh number of the screens and bed thickness. The presence of baffles was found to increase the rate of cementation. The data were correlated by a dimensionless mass transfer correlation suitable for the design and operation of large scale cementation reactors.

By Ronald E. Heuer, Debra L. Virgens

INTRODUCTION Behavior of clay soils in response to tunneling is reasonably well understood by reference to the tunnel stability factor NT = Pz/su (Peck, 1969; Heuer, 1974). With this analysis tool, care must be taken to use a value of clay shear strength which represents the actual mass strength, considering such factors as slickensided fissures often found in stiff and hard clays. Behavior of clean sand and gravel soils is also reasonably well understood. Above the water table these soils must be assumed to act as running ground unless they are known to have significant cementation or have a very dense and angular interlocked grain structure. Below the water table they must be tunneled using some form of groundwater control such as dewatering, grouting, freezing, or internal fluid pressure in the tunnel such as compressed air or a slurry tunneling machine. The internal fluid pressure must approximately balance the external water head. Without such precautions these soils behave as flowing ground and may yield large volumes of water flow into the tunnel. A wide range of very fine sand, silty sand, cohesionless silt, and clayey sand soils exist in nature in a variety of geologic environments. The behavior of these soils in response to tunneling, and guidelines for anticipating their behavior, are not well described in the literature. Because of their content of fine particles, these materials may behave as if they initially have appreciable cohesion and moderate to low permeability. They may exhibit significant standup time, and require tunnel internal fluid pressure (compressed air or slurry pressure) less than the full external water head. It is important to be able to estimate the behavior of these soils when planning construction methods. For example, if the external water pressure is 140 kPa (20 psi), but soil stability at the tunnel face can be achieved as a compressed air pressure of 80 kPa (12 psi), a large cost savings may result.

Jan 1, 1987

By William F. Daly, William H. Hansmire

Installation of initial tunnel support is often the most uncertain element of work in the design of, and a contractor bidding on, construction of a rock tunnel. The risks the construction contractor and owner assume are delineated to a great extent in the technical specifications portion of the contract documents. It is intended that this paper identify current practices for specifying initial tunnel support and the impacts each case has on the assignment of risks associated with providing the initial tunnel support. Examples of recently completed tunnel designs are given.

Jan 1, 1985

By Kirsten Corin, Belinda McFadzean, Cyril O’Connor, Jenny Wiese

The Bushveld Complex of South Africa contains almost 90% of the world’s reserves of platinum group minerals (PGMs). In the flotation of PGMs, there are significant challenges arising from the need to treat ever-decreasing grades of the relevant ore deposits. The major challenge in the flotation of these ore bodies is the control and management of the gangue minerals, particularly silicates such as orthopyroxene, plagioclase feldspar, and pyroxene which are often rimmed with talc which makes them naturally floatable. It has been shown that various polysaccharide depressants such as CMC and guar have different properties in terms of depressing the gangue minerals. Since the PGMs are often associated with sulphides, copper sulphate is widely used as an activator in PGM flotation but can inadvertently activate the gangue minerals as well as reduce the recovery of PtTe2 which accounts for up to 40% of the Pt in the Platreef ore body. Depressants also reduce the mass of solids reporting to the froth and can thus destabilise the froth. This effect on the froth can be mitigated by using higher frother dosages or water of higher ionic strength. Reducing chromite recovery is of critical importance since high levels may negatively affect the downstream smelting process. Chromite recoveries can however be reduced through the application of gravity separation or reducing entrainment through reduced water recovery. In summary, due care needs to be taken to carry out site test work to develop an optimum ratio of collector, frother, activator, and depressant to ensure that the highest grades and recoveries of the PGEs are obtained while reducing depressant dosage as much as possible.

By · J. B. Boisvert, O. Leuangthong, T. Acorn

Optimizing final pit limits for stochastic models provides access to geologic and economic uncertainty in the pit optimization stages of a mining project. This paper presents an approach for optimizing final pit limits for a highly variable and geologically complex gold deposit. A heuristic pit optimizer is used to manage the effect of geological uncertainty in the resources within a pit shell with multiple uncertainty rated solutions. The uncertainty rated pit shells follow the meanvariance criterion to approximate the efficient frontier for final pit limits. Stochastic dominance rules are then used in a risk management framework to further eliminate sub-optimal solutions along the efficient frontier. This results in a smaller set of final pit shells that could be further analyzed for production scheduling. Additionally, the original solutions are analyzed for changes in the mining limits and two regions are targeted as potential regions for further exploration.

By · J. B. Boisvert, O. Leuangthong, T. Acorn

Optimizing final pit limits for stochastic models provides access to geologic and economic uncertainty in the pit optimization stages of a mining project. This paper presents an approach for optimizing final pit limits for a highly variable and geologically complex gold deposit. A heuristic pit optimizer is used to manage the effect of geological uncertainty in the resources within a pit shell with multiple uncertainty rated solutions. The uncertainty rated pit shells follow the meanvariance criterion to approximate the efficient frontier for final pit limits. Stochastic dominance rules are then used in a risk management framework to further eliminate sub-optimal solutions along the efficient frontier. This results in a smaller set of final pit shells that could be further analyzed for production scheduling. Additionally, the original solutions are analyzed for changes in the mining limits and two regions are targeted as potential regions for further exploration.

By M. A. Oskouei

Draglines are the main energy consumers in strip mines. Given the growing cost of energy and environmental concerns, it is important to properly understand dragline energy efficiency. The goal of current research at Missouri University of Science & Technology is to account for operator practice and operating conditions in modeling dragline energy efficiency. This paper presents preliminary correlation analysis and a framework for stochastic modeling of dragline energy efficiency. Thirteen operating parameters (including cycle times, payload, swing angle, and height of dump pile), operator working schedules, operating conditions, and drag, hoist, and swing energies were monitored for an 85 yd3 dragline. Operator effects were examined by two-sample t-tests. The relation between the parameters and energy consumption were assessed by correlation analysis and a stochastic modeling framework has been proposed for dragline energy efficiency. The results show that operator effects are significant (p< 0.05) and energy efficiency is correlated with operating parameters. The completed model will help the coal mines better predict energy consumption, with uncertainty, for different operating conditions.

Feb 27, 2013

By Peter Kowalczyk

Magnetic surveying and map production is well established in land based mineral exploration. Magnetic data are routinely used to map geology in covered terrains, to estimate the depth to basement in overburden covered areas, and to identify altered zones, mineralization, bedding attitudes, and fault networks both regionally in map view, and through interpretation to depth in 3D. Best practices for magnetic survey methods and magnetic interpretation exist in all areas of land based geophysical survey methodology - mineral exploration, hydrocarbon exploration, geological mapping, archeological mapping, and in military applications. At sea, and particularly under the sea, sophisticated magnetic surveys are being done, but it can be argued that these are primarily in niche applications, for example in naval mine-hunting and UXO applications. Magnetic data is not normally collected on AUVs and ROVs conducting mapping and hydrographic survey operations. OFG has developed physical and mathematical calibration routines so that magnetometers can be mounted directly onto AUV and ROV bodies where significant heading errors and magnetic gradients exist. This simplifies the routine deployment of magnetometers on AUVs and ROVs for mineral exploration and other magnetic survey applications without the need for towed bodies, ungainly mounting frames, or degaussing of the survey equipment. Our experience shows that magnetometers can be operated routinely on AUVs and ROVs and that with careful processing useful maps can be produced routinely at low cost.

Sep 1, 2014

By Nilabjendu Ghosh, Satyendra Kumar Singh, Gautam Banerjee, Harshit Agrawal

High-production methods like longwall mining with hydraulic powered supports are necessary to increase underground coal production in India. Longwall mining had a mixed success record for Indian geo-mining conditions. In this paper, an analysis is presented to optimally design an array of chain pillars in multi-seam longwall mining panels in the deepest coal mine in India. The study found that a chain pillar of 80-m width and 195-m length is necessary for long-term stability without any reinforcement. It was also observed that an optimum chain pillar can be designed by providing suitable side reinforcement (side bolting) which will reduce the chain pillar dimensions to 55-m width and 160-m length. Optimum design of chain pillars will reduce the coal locked up in these chain pillars by ~ 77%. This will also reduce the gestation period of longwall mining panel development. This paper also evaluates the maximum tensile subsidence strain induced at the surface and finds that the values are within the safe working limit of 3 mm/m. Thus, this paper finds direct application in the design of future multi-seam retreating longwall mining panels in Indian geo-mining conditions.

By Nilabjendu Ghosh, Satyendra Kumar Singh, Gautam Banerjee, Harshit Agrawal

High-production methods like longwall mining with hydraulic powered supports are necessary to increase underground coal production in India. Longwall mining had a mixed success record for Indian geo-mining conditions. In this paper, an analysis is presented to optimally design an array of chain pillars in multi-seam longwall mining panels in the deepest coal mine in India. The study found that a chain pillar of 80-m width and 195-m length is necessary for long-term stability without any reinforcement. It was also observed that an optimum chain pillar can be designed by providing suitable side reinforcement (side bolting) which will reduce the chain pillar dimensions to 55-m width and 160-m length. Optimum design of chain pillars will reduce the coal locked up in these chain pillars by ~ 77%. This will also reduce the gestation period of longwall mining panel development. This paper also evaluates the maximum tensile subsidence strain induced at the surface and finds that the values are within the safe working limit of 3 mm/m. Thus, this paper finds direct application in the design of future multi-seam retreating longwall mining panels in Indian geo-mining conditions.

By David Smith, Bernie Martin

The Queens Bored Tunnels consist of 11,000 feet of 19&apos;-6" inside diameter tunnels mined through rock, mixed face and dense glacial till, constructed with bolted gasketed one pass reinforced concrete liner. The tunnels are to be excavated with a pressurized face TBM, either EPB or slurry. The construction of the tunnels will require ground stabilization in the mixed face area, instrumentation and monitoring of railway infrastructure, underpinning of bridges, relocation and protection of utilities, demolition of some industrial buildings, construction of open-cut approach tunnels and emergency exits and vent plants. The purpose of this paper is to describe the scope of work, the suggested methodology and the proposed construction schedule.

Jan 1, 2005

Let’s start off with your assessment of the mining industry. Today, the status of the mining industry is stronger than it has been over the previous few years. While mining continues to be a major part of the world’s economic foundation, the industry is gaining strength due to rebounding metals and minerals prices. And now, with these rising prices and the changes the industry instituted during the years when mining-related commodities were selling at low prices, our stronger, more productive and internationally competitive industry should flourish. Mining remains an essential business and the industry is far ahead of the game when it comes to the trend of globalization as a key to sustained growth. Also, the industry continues to realize increased productivity through technological innovations. And an increasing number of countries are moving towards capitalism, which opens doors for exploration and mining within their borders. After looking at all of these factors, I believe that the mining industry will only continue to gain momentum in the future.

Jan 1, 2004

By D. Bessinger, J. M. A. Geldenhuis

High titania slag is produced from the smelting of ilmenite. These slags contain approximately 85 per cent TiO2 and consist mainly of a M3O5 solid-solution phase. During cooling the slag can decrepitate to a fine particulate material, which decreases the value of the product. Based on X-ray diffraction analyses of the decrepitated slag after cooling, it was found that the M3O5 phase had almost disappeared. The disappearance of the M3O5 phase was linked to oxidation of the slag. A M6O11 phase formed in the decrepitated slag. It is postulated that decrepitation of high titania slag is caused by volume changes due to the oxidation of the M3O5 phase in the slag.

Jan 1, 2005

By R. Kaushik

According to the U.S Department of Energy (DOE), mineral processing activities including comminution (size reduction) uses 4% of the world electrical energy consumption. Such numbers reinforce the need to invest in energy savings initiatives in order to produce more using less. ENERGY EFFICIENCY OPPORTUNITIES AND CHALLENGES IN MINING OPERATIONS In addition, DOE, in its Mining Industry Energy Bandwidth Study, has identified huge potential for energy savings for the coal, metals and mineral industries. Even knowing the overall causes of energy waste and some potential tools for remediation, mining companies may struggle to apply such tools and get the desired results due to the following reasons: ? Limited staff ? Lack of accurate economic and investment analysis to justify energy savings projects ? Lack of knowledge to identify low or no-cost savings opportunities ? Internal competition for resources According to the workforce and talent management experts, the Talent Strategy Advisors, the demand for mining engineers is expected to exceed supply by 30% by 2013. Mining personnel are likely to be burdened with increasing and varied workloads with limited training. This will result in the need for automated and simple tools to support energy efficiency activities. Mining engineers will simply not have the time and resources to create such tools, collect and analyze the data to make decisions, and track results.

Feb 27, 2013