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By Roger K. McLimans, Venkatramaiah N. Vasudev, Christian Knudsen, Stefan Bernstein, Dirk Frei

Computer Controlled Scanning Electron Microscopy (CCSEM) analyses of sediment samples from coastal regions of Kerala and Tamil Nadu states and the heavy mineral deposits of Chavara, South India, show large lateral differences in the titanium content in ilmenite due to varying degrees of iron leaching. As the depositional environments for the sands with varying degrees of ilmenite alteration are comparable, the cause for the different degree of alteration is due to differences in the primary source of the ilmenite or to differences in the geochemical history of the ilmenite grains during transport from source to deposit. The CCSEM analyses of the heavy mineral fractions show that source of sediments with a high content of titanium-enriched ilmenites, mainly the heavy mineral deposit around Chavara, resides in the khondalite belt of South India (granulite facies metasediments). The less titanium-enriched ilmenites are sourced from other rocks in the area such as the charnokites. Those conclusions are based on the high MgO content in the leached ilmenites, chemical composition of the accompanying garnets (low CaO and high MgO), and the concentration of aluminum-rich minerals in the sands.

Jan 1, 2005

By A. K. Martin

Adaptive management can be described as a structured, iterative process of robust decision making in the face of uncertainty, with a goal of reducing uncertainty over time through system monitoring. Adaptive management is a tool which can be applied to not only change a system, but learn about the system (Holling, 1978). Adaptive management has been used in ecosystem management for years and guidance is provided in a variety of handbooks and publications. Adaptive management can be applied to industrial facilities and mines through the use of an adaptive environmental management plan (AEMP) and associated practices. The goal of this paper is to provide an explanation of how the plans and practices support regulatory agency approvals and permitting, span the life-cycle of mines, manage uncertainty, and assist in addressing mining impact and legacy issues. AEMPs and associated practices are useful tools to address the uncertainties in identifying, evaluating, and managing impacts of proposed new and modified mining facilities undergoing environmental review. Once a proposed project is approved, the AEMP continues as a living document, being informed, revised, and adapted by the operations. The AEMP can serve as an ongoing management tool for describing and evaluating environmental impacts, continuing in operations into post reclamation. If initiated during planning and environmental review of a project (and in some locations such as the United States [U.S.], the preparation of an Environmental Impact Statement (EIS)), the AEMP becomes a basis to identify, monitor, and manage potential project environmental impacts. Development of an AEMP for an operating mine is also beneficial since there are generally developing and ongoing environmental issues at those facilities as well. Over time, the AEMP is adapted to changing requirements and conditions including those anticipated and unanticipated. Ever increasing scrutiny of mining projects and the complexities of the EIS process highlight the uncertainties inherent in impact predictions. In making the momentous decision of initial project approval, these uncertainties can discourage the regulatory agencies? actions and create stakeholder anxiety and controversy about a project. A well-designed AEMP can support the decision to approve an EIS and enable a project to move forward. Additionally, an AEMP can inform financial assurance estimates and revisions over the life of a mine providing all parties including the citizens of the surrounding communities with greater confidence that potential environmental impacts and risks will be well managed.

Feb 23, 2014

By B. C. Paul, R. Q. Honaker, K. Ho

Recent research has shown that froth flotation is not effective at treating fine coals (-28 mesh) containing a large portion of middling particles. Due to their relatively large density differences, middling particles can be separated more efficiently using gravity-based processes. The ability of gravity separators to treat fine particles has been limited by the lack of particle inertia relative to the surface drag forces. However, particle inertia can be enhanced by the application of a centrifugal field. A commercial-scale centrifugal Falcon concentrator capable of treating a mass flow rate of greater than 1 tph continuously has been used to evaluate its feasibility for treating fine coal as an alternative to froth flotation. Tests conducted on a -28 mesh fine coal circuit feed have found the Falcon concentrator to be very effective at cleaning the 28 x 325 mesh size fraction. For an Illinois No. 5 coal sample, the ash content was reduced in the 100 x 325 mesh size fraction from about 18% to 8% while achieving a high combustible recovery value of nearly 97%. In addition, the total sulfur content was substantially decreased from 2.6% to 1.7%. The effects of the critical operating parameters on separation performance have been studied and their values optimized.

Jan 1, 1995

By S. Mukusha

Electronic spreadsheets are the most common and readily available software applications for analyzing and modeling quantitative problems. Spreadsheets can offer a vast array of opportunities for the analysis and modeling exercises encountered in the field of geomechanics. This study explores the potential for using spreadsheets of in the practice geomechanical engineering. The study also examines some of the barriers to widespread use of spreadsheets. Best practices and guidelines for overcoming potential pitfalls are discussed and highlighted through a case study.

Jan 1, 2000

By I. Douni

The aim of this study is to synthesize hydrated compounds of calcium silicate (tobermorite) using as siliceous source perlite milling process wastes, containing more than 70% of SiO2. Calcium silicate hydrates are mainly used for construction of lightweight building materials, plasters, tiles and filters. The effect of temperature, time and particle size of perlite on the quality and composition of the solid product was studied. The solid products were characterized by X-ray Diffractometry, Differential Thermal Analysis and the amount of Acid Insoluble Residue. The synthesis of tobermorite was per-formed by the hydrothermal treatment of perlite waste with a saturated calcium hydroxide solution at a molar ratio CaO/SiO2 of 1, liquid to solid ratio 10 mL/g and 1% w.t. NaOH addition. Three experimental sets were performed. In the first series of experiments the synthesis temperature was kept constant at 205°C while the synthesis time varied from 0.5 h to 24 h. In the second experimental series the synthesis time was kept constant at 2 h while the temperature varied between 150°C and 245°C. In the third experimental set the temperature was 205°C and the reaction time was 2 hours and two perlite waste size fractions were used, a coarse (d50=18 µm) and a fine grained one (d50=8 µm). Reaction products consisted of semicrystalline calcium silicate hydrate (I) and crystalline Al-substituted tobermorite or a mixture of both. An isomorphic Si4+ ions substitution with Al3+ ions in the hydrated calcium silicate lattice was detected by thermal analysis. The experimental results show that good quality crystalline Al-tobermorite can be produced after 6 hours of autoclaving at 205°C or after 2 hours of hydro-thermal treatment at 225°C. Generally, the in-crease of synthesis temperature or time favors the crystallization of calcium silicate phases and enriches them in aluminum. The use of fine grain size perlite is more efficient for the hydrothermal synthesis of calcium silicate hydrates.

Jan 1, 2006

By Scott Rosenthal, Dave Gilkey, Theresa Stack, Daniel Autenrieth, Ciara Kremer

Jackleg drill operators are exposed to harmful levels of hand-arm vibration (HAV). Anti-vibration handles and gloves provide modest reductions in HAV exposures and forearm muscle exertion from the use of anti-vibration handles and gloves by jackleg drill operators. The goal of this pilot study was to investigate changes in HAV with the use of anti-vibration gloves and handles compared to forearm muscle exertion experienced by operators and measured with surface electromyography (EMG). Five subjects operated the drill under four different cases: no anti-vibration controls, anti-vibration gloves only, anti-vibration handle only, and simultaneous anti-vibration handle and glove use. Muscle exertion was expressed as a percent of maximum voluntary contraction (%MVC) and was compared using Welch’s ANOVA with Games-Howell post hoc comparisons. The case with both anti-vibration controls in use simultaneously (largest grip diameter) was associated with a mean %MVC of 36.13% during operation for all forearm muscles combined, which was significantly higher than that of the other cases (p < 0.05). There were no statistically significant differences in mean HAV exposures. The anti-vibration handle with anti-vibration glove case only increased the maximum allowable exposure time by 8 min as compared to the control case without any anti-vibration controls. These results suggest that the modest HAV exposure reductions from the use of anti-vibration handles and gloves may pale in comparison to the increased muscle exertion resulting from their use, and this trade-off among jackleg drill operators is a potential concern that warrants further investigation.

Jul 12, 2021

By A. Nieto

This article is a review of previous discussions about underground mining method selection and classification with the purpose to clearly define and classify the two groups of variables (indicators) involved in the mining selection process: key deposit indicators (KDIs) and key mining method indicators (KMIs). This paper provides a simple and clear approach for the classification and selection of a feasible underground mining method based on a predetermined set of favorable deposit characteristics, which are defined as key deposit indictors (KDIs). This article also gives a summary of the key advantages and disadvantages associated with every underground mining method based on their key mining indicators (KMIs). The selection method given in this paper is based on defining field KDIs and comparing them to the KDIs that are favorable to every considered mining method. By cross validating a matrix of favorable KDIs, the paper presents a simple approach to rank several underground mining methods using a scale from favorable to less favorable accordingly to the ore deposit characteristics (KDIs). KMIs are used to further complement KDI rankings by analyzing every method’s KMI performance based on the expected productivity of the mining operation being considered. To further assist the reader through the selection process, this paper gives basic sketches representing each of the primary underground mining methods discussed in this paper. Each method is given using the same 3D isometric view as spatial reference to assist the reader with visual interpretation and comparison between methods.

Jan 1, 2010

By T. Pool

Introduction After two decades of contraction and consolidation, the uranium industry has seen a recent major expansion. Rapidly increasing uranium prices and the ability to raise speculative capital in share markets worldwide have brought over 300 new participant companies into the uranium industry: “juniors” as they are known. These companies participated in a global land rush for known deposits as well as for prospective land positions in order to secure a “piece of the action” for their respective portfolios. Mostly publicly-traded companies, these “juniors” have captured the attention of world’s investing public with spectacular gains; as much as 1,000s of percent in less than four years. The initial phase is over, however, and these companies must now prove that they can be successful in exploration or production.

Jan 1, 2007

By Kaige Zheng, Hongwei Wang, Tong Wang, Yanjun Li, Yongping Wu, JIANQIANG JIAO, Baolin Jiang

Due to the influence of economic development on the demand growth of coal resources, many mines in China have gradually entered deep mining. When the roof of deep coal seam is hard rock, it is easy to cause strong ground pressure with the advance of the working face, which seriously threatens the safety of coal mining. Taking 31,104 working face of a mine as the engineering background, this paper studies and compares the deformation characteristics and stress transfer evolution law before and after the presplitting of the hard roof through the combination of physical similarity simulation, numerical calculation, and field measurement, based on the analysis of the interaction relationship between the breaking and collapse of the composite hard roof, and verifies the treatment effect of hydraulic presplitting through field measurement. The results show that: (1) In the early stage of mining under the composite hard roof, the lower roof is mainly subjected to tensile failure, the voussoir beam structure formed is relatively unstable, and the stope is prone to impact. When the mining distance of the working face is large, the breaking rotation of the upper hard roof voussoir beam causes pressure damage to the lower hard roof, causing the lower hard roof voussoir beam structure to slide and lose stability, resulting in strong ground pressure in the working face. (2) After presplitting of composite hard rock stratum, in the early stage of mining, the range and degree of rock stratum damaged by presplitting are small except for the hard rock stratum itself, and the presplitting effect is not significant. When mining to the first square position, the roof is damaged in advance by presplitting, the overall plastic damage range increases, the damage form area increases, and the damage degree deepens. The vertical displacement of the composite hard roof increases rapidly, and the presplitting effect is remarkable. (3) The evolution characteristics of roof principal stress transfer show that under the dual effects of mining and presplitting, the roof tensile stress area above the goaf is large, the rock failure horizon rises, and the roof failure height is high and the failure degree is deep. The stress concentration degree of the coal mass in front of the goaf is reduced, and the stress concentration range is transferred to the rock mass in front. With the advance of mining, the hard roof in front can break and caving in time, so as to avoid rock burst disaster caused by large suspended roof area. The field ground pressure monitoring shows that the average periodic weighting interval, weighting range, peak value before weighting, and peak value during weighting of the working face after presplitting decrease by 53.5%, 38.03%, 8.63%, and 5.96%, respectively, which effectively reduces the weighting intensity and ensures the safe and efficient mining of the working face.

May 16, 2023

By Jack S. Greber

The mining industry generates an estimated 2.3 billion tons of solid waste each year and the total accumulated mineral resource solid waste at both active and inactive mine sites, approaches 30 billion tons. Five industries generate 85 percent of mine solid waste: copper, phosphate, iron, uranium, and coal. Over the past several years, the Federal government has shown increasing interest in the proper disposal of solid wastes generated by the mining industry. Three new pieces of federal legislation have been passed recently beginning with the most comprehensive regulatory authorization passed in 1976, the Resource Conservation and Recovery Act (RCRA) which has been amended to the Solid Waste Disposal Act Amendments of 1980. RCRA is implemented and enforced by the Environmental Protection Agency (EPA) and intended to control municipal and industrial solid wastes. Next came the passage of the Surface Mining Control and Reclamation Act (SMCRA) of 1977 which is implemented and enforced by the Department of Interior to control coal surface mining and the surface effects of underground coal mining, and finally, the recent Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978 implemented by EPA and enforced by the Nuclear Regulatory Commission (NRC) to control uranium mill tailings disposal.

Jan 1, 1981

By Michael J. Mujadin

Since the late 60&apos;s, planners at American Natural have known that natural gas supplies from traditional sources will be insufficient to maintain a consistently high level of service in the near future. This dwindling of traditional gas reserves will force American Natural and other gas companies to seek new and more exotic sources of supply. In recent years a number of alternative supply sources were considered, including arctic gas, LNG, and SNG based on naptha, LPG and coal feedstocks. Several combinations, all of which included SNG from coal were selected as the most suitable alternative sources of gas supply for American Natural, and thus our company embarked on the formation of a coal gasification project in the early 70&apos;s. Work began with the evaluation of available coal supplies in the United States in late 1970. Western North Dakota was selected for several reasons: large contiguous reserves of lignite were available near the surface, similar to German brown coal for which the Lurgi gasification process was originally developed; the conditions for land reclamation in the area are favorable; and the people in the area have a positive attitude toward well ordered development.

Jan 1, 1977

By L. Harris

The gold mining and ore processing operations of Minera Yanacocha S.A. are 10cated in an area 4,000 meters above sea level in the Peruvian Andes same 600 km north of Lima and 20 km north of Cajamarca. The joint venture partners are Newmont Second Capital (USA); Compania Minera Condesa (Peril); Mine Or (France) and the IFC. Newmont manages the operation. The Yanacocha district comprises several areas with mineralization evidence. The first ore with minable reserves of 28 million tonnes of ore assaying about 1.4 gpt Au is called Carachugo and is being mined and treated at the rate of 14,000 tonnes of ore per day by open pit mining methods. ROM ore is dump leached and the gold recovered in a Merrill Crowe plant. The plant design incorporates some unusual considerations to overcome the problems of the high rainfall in this area and assure the protection of the environment.

Jan 1, 1994

By D. K. DeForest

The olfactory system (sense of smell) is crucial to the ability of fish to avoid predators, recognize kin, and synchronize reproduction (Baldwin et al. 2003). Copper (Cu) has been shown to impair olfaction in juvenile freshwater life stages of salmonids (including Pacific salmon and trout) in some laboratory experiments; and in the United States, public concerns have been expressed that current regulatory criteria for Cu in fresh water are not adequately protective of olfactory function in salmonids (e.g., OSU 2007; Pearson 2007). These concerns have largely been raised because some Cu concentrations that have caused olfactory impairment in salmonids in the laboratory are less than Cu concentrations that have been shown to reduce salmonid survival, growth, or reproduction (the effects endpoints that are typically considered in deriving ambient water quality criteria). However, two important and interrelated points that must be considered: (1) freshwater Cu criteria are "driven" by the sensitivities of several invertebrate species that are more sensitive than the olfactory impairment threshold in salmonids when (2) the influence of water chemistry on Cu bioavailability is properly considered in deriving Cu criteria. Bioavailability refers to the ability of various chemical forms of Cu to interact with receptors on the surface(s) of organisms and thus directly cause toxicity or uptake by the organisms. The toxicity of Cu and other metals to aquatic organisms is a function of water chemistry. For example, acute Cu toxicity in fresh water generally decreases as pH, water hardness (Ca2+ and Mg2+), alkalinity, and dissolved organic carbon (DOC) concentrations increase (Meyer et al. 2007). The U.S. Environmental Protection Agency (USEPA) has recommended hardness-based freshwater aquatic life criteria for Cu and other metals since the 1980s (e.g., USEPA 1985); and hardness-based metals criteria decrease (i.e., become more restrictive) as water hardness decreases. More recently, the USEPA has recommended freshwater aquatic life criteria for Cu based on the biotic ligand model (BLM; USEPA 2007), which accounts for the influence of multiple water chemistry parameters, including DOC, pH, alkalinity, Ca2+, Mg2+, and several other cations and anions. The BLM-based Cu criteria generally decrease as DOC concentration, pH, alkalinity, and water hardness decrease. Because DOC has a stronger influence on Cu bioavailability than water hardness, hardness-based and BLM-based Cu criteria can differ considerably. For example, in water that has low DOC and high hardness, the hardness-based Cu criterion would be relatively high (because it is driven by the high hardness) but the BLM-based Cu criterion would be relatively low (because it is driven by the low DOC). Thus, any evaluation of the protectiveness of Cu criteria against a given effect, such as olfactory impairment, must properly account for the chemistry of the exposure water. Meyer et al. (2013) compiled data on Cu-induced olfactory impairment and olfactory-induced behavioral effects from tests in which BLM parameters were measured. They demonstrated that the USEPA&apos;s BLM-based freshwater life criteria for Cu are protective against olfactory impairment, because it adequately accounts for water chemistry (whereas the USEPA&apos;s hardness-based Cu criteria are not consistently protective). Olfactory impairment by Cu is now receiving increased attention in Canada and Europe (e.g., Wall 2013; Stang 2013). Accordingly, in this paper we have expanded the analysis of Meyer et al. (2013) to consider copper guidelines from various other countries and whether these guidelines are protective against olfactory impairment.

Feb 23, 2014

By J. R. Goode

The first part of this paper comprises a general discussion on refractory gold ores and their mineralogy processing methods now in use are reviewed and test procedures for the important methods are discussed. Factors determining the selection of a process are outlined. The paper includes a survey of production plants using pressure oxidation, roasting and biological oxidation to process refractory ore. The status of processes under development is briefly reviewed.

Jan 1, 1993

By Moussa Wone, Jeff Peterson, Filippo Azzarà, Daniele Nebbia

The DC Water and Sewer Authority's Long Term Control Plan includes tunnels, sewer separation, pumping station rehabilitation and green infrastructure to reduce combined sewer overflow (CSO) discharges to the District waterways. The Northeast Boundary Tunnel is a deep, large sewer tunnel that will reduce CSO discharges; signifi- cantly mitigate known chronic flooding in the Northeast Boundary drainage area and improve the water quality of the Anacostia River. This paper presents the unique combination of Owner and Contractor perspectives of the entire Project from conception through procurement, execution, and contract management, providing lesson learned, chal- lenges encountered, and solutions implemented to deliver the Project successfully.

Jun 23, 2024

By F. G. Heivilin

There will be 3 billion people moving into cities by 2050. Permitting is both the biggest obstacle and the biggest opportunity for mining. The problem is not if we have the right minerals, but how we can permit and produce it in a ?Sustainable? manner. A ?Permit? and a ?Sustainable Development Plan? may soon be the same thing. How do we produce the minerals we need with: 1. The lowest possible carbon footprint. 2. Social license from community outreach by being a catalyst and not a problem in a ?Green World.? 3. Enhanced water supply during all stages of production. 4. Meeting requirements of our customers for service, quality, & cost. How important is it to have a complete ?Sustainable Development Program?? First, no plan is complete!!! It is a work in progress subject to continuous improvement. We need to work together to get the results we want. The goal of the world communities is to become carbon neutral by 2050. What is the mining community?s goal? Do we have one???? When a Clorox, Colgate Palmolive, Wal-Mart, Toyota, or Caterpillar buys a product, what are your chances of getting an order without a good program in place? The answer is it will be difficult or impossible shortly and you will be requiring the same thing with your suppliers. This is an opportunity if you are in the lead and it soon will be a necessity for most mining and processing companies requiring much extra effort to catch up. For some mines it was a necessity to get most of the SD plan to get permitted. The number of companies in the extractive industries with a full Sustainable Development Programs is expanding rapidly as shareholder demands for transparency continue to grow.

Feb 27, 2013

The Mining Foundation of the Southwest will hold its 14th annual American Mining Hall of Fame awards banquet Saturday, Dec. 7, 1996 at the Leows Ventana Canyon Resort in Tucson, AZ. Each year, preceding the Arizona Conference of SME, the Mining Foundation sponsors this banquet to honor outstanding contributions by people in the mining industry. A permanent display of honoree vitae is located at the Arizona Historical Society in Tucson. Each year, one living award recipient and up to two honorees from mining’s history are chosen by the hall of fame committee and the board of governors of the Mining Foundation. In 1989, the foundation also established a medal of merit to recognize outstanding individual technical and professional contributions to the mining industry. And, in 1995, an award was created to recognize contributions made by companies and individuals in partnership with the mining industry. This year’s inductee is Richard de J. Osborne, chairman, president and chief executive officer of Asarco. He will also be the featured speaker at the banquet.

Jan 1, 1996

By Savita Schlesinger, Mike Hanna, Nathan Scalla, James O’Shaughnessy, Steve Miller

Loudoun Water’s Quarry A (Milestone Reservoir) project involves conversion of a rock quarry to a billion-gallon raw water reservoir. The project includes a new 40 MGD pump station, deep intake shaft, and three drill and blast intake tunnels for accessing the reservoir. Due to concerns regarding constructability and construction risks, the project design was paused while a Construction Manager At-Risk (CMAR) contractor was procured. The CMAR contractor was engaged collaboratively with the design team to provide risk and constructability input for refining the design. Aspects of the original design, design modifications, and benefits of the CMAR collaboration will be presented.

Jun 13, 2023

By S. J. Schatzel, V. Gangrade

A ventilation research study was conducted by the National Institute for Occupational Safety and Health and a cooperating trona mine in the Green River basin of Wyoming, USA. The mine operation uses the longwall mining method in trona bed 17, a commonly mined unit in the region. The longwall face length is 228 m (750 ft), and caving on the face occurred up to the back of the longwall shields. The mine is ventilated using a main blowing fan and a bleeder shaft. For this study, sulfur hexafluoride (SF6) tracer gas was released in two separate monitoring experiments. For the first experiment, tracer gas was released on the face, this test focused on airflow along the longwall face of the active panel. Face test showed the airflow patterns to be more complex than just head-to-tail flow in the main ventilation air stream on the active panel. For the second experiment, tracer gas was released 2 crosscuts inby the face on the headgate side, this test focused on gas transport in the mined-out portion of the same active panel. Gob test showed a pathway of movement through the front of the active panel gob that moved outby from the tailgate corner. The primary pathway of tracer gas movement in the active panel gob was towards the headgate and tailgate bleeders and out of a bleeder shaft. The rate of movement towards the back of the gob was measured to be 0.19 m/s (37 fpm).

By H. Sevim

Placement of coal combustion byproducts into abandoned sections of underground coal mines for the purpose of subsidence mitigation has been investigated in Illinois. Several handling and transportation systems have been examined. Prototype pneumatic and hydraulic placement systems have been developed and demonstrated. The demonstration site, Peabody No. 10 mine in Pawnee Illinois, is selected as a case study. It is found that, for a project of 5 years, transporting 150,000 tons of byproduct annually from a power plant located 32 km (20 miles) to the mine would cost $1.80 per ton and placement into underground would cost $3.07 per ton.

Jan 1, 1998