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By R. A. Meyr, K. A. Perry

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by the U.S.Congress. The U.S. Mining Safety and Health Administration subsequently released the Final Rule on Refuge Alternatives for Underground Coal Mines, which required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. The following paper documents the research that was performed on a structural wall to be used in conjunction with a breathable air system to create a refuge alternative. A 103.4-kPa (15-psi) safe haven polycarbonate wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics. The successful safe haven wall design was modeled for an actual underground coal mine environment using the explicit finite difference formulation program FLAC3D to determine the responses of the wall and surrounding strata within a mine. A full-scale design was fabricated and installed in an underground coal mine to determine any construction constraints and as a final step in proof of concept for the safe haven wall design. This paper is meant to introduce the reader to a new wall concept to be used in conjunction with current technology.

Jan 1, 2013

By S. Veeramasuneni

The sign of the surface charge for alkali halides in their saturated brines has been established from non equilibrium electrophoresis measurements and on this basis the flotation response of alkali halides was explained based on the adsorption of oppositely charged collector colloids by heterocoagulation. These surface charge results for alkali halides are generally as expected from simplified lattice ion hydration theory with some exceptions, specifically LiF, KCI, NaCl, KBr, RbBr, KI, and Rbl .The presence of natural oxygen defect states in the crystal lattice and the inaccuracies involved in the gaseous ion hydration free energy values used appear, in past, to be responsible for these deviations. The presence of natural oxygen defect states in KCI, KBr, RbBr, and Rbl as characterized by UV Nis absorption, was found to account for their anomalous surface charge. Further, other positively charged alkali halides, LiF, NaCl and KI, were found to be free of oxygen defect states. Nevertheless, oxygen defects can be created in these alkali halides to make them negatively charged and has been demonstrated for NaCl. Such negatively charged NaCl can be readily floated with positively charged amine collector colloids thus confirming the surface charge/collector colloid adsorption theory.

Jan 1, 1996

By Dennis C. Martin

Assessment of the potential for mining induced subsidence and determination of ultimate design requirements for a mining operation should be based on a number of assessment approaches. Although the rock mechanics engineer has a variety of limit equilibrium and numerical modeling tools available for assessment and prediction of subsidence effects, empirical approaches based on precedent experience provide a powerful tool for calibration/verification of analytical models and prediction of subsidence. Three separate analyses approaches have been applied to the assessment of potential subsidence for a proposed block caving mine in eastern Canada. The investigations have included an assessment of documented historical information from previous block cave mining at the site, deterministic analyses using limit equilibrium approaches to assess kinematically possible failure mechanisms, and three-dimensional numerical modeling techniques. Analyses results have been used and compared with precedent experience and documentation of subsidence behavior from previous mining to optimize the subsidence predictions for the proposed mine.

Jan 1, 1998

By R. C. Milici

Historical production data and reserve decline rates can be used both to predict future coal production rates and to estimate when the reserve will be depleted. Reserve estimates inferred herein from historical production data and decline rates are commonly lower than estimates made from geologic data. The latter include significant amounts of lower quality (deeper, thinner, higher sulfur) coal which may be mined when the better deposits are depleted.

Jan 1, 1997

By W. J. Dolinar

The U.S. Bureau of Mines implemented the Fe2+ /Fe3+-SO2 anode reaction in a Cu electrowinning cell with full-size electrodes. Electrowinning was conducted using industrial electrolyte at 258 A/m2 (24 A/ft2) and 40 'C. Manifold injection of electrolyte provided circulation between the electrodes. Five-day operation using an optimized manifold gave an average cell voltage of 0.94 V at 89% current efficiency, which amounted to an energy savings of 2.82 MJ/kg (0.355 kW-hr/lb) compared to conventional electrowinning. Acid misting was completely eliminated, and SO2 concentration 23 cm (9 in.) above the cell averaged 0.06 ppm.

Jan 1, 1995

By R. Pinksen

The IOC Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1.0 m x 1.0 m x 1.0 m; 39 inches x 39 inches x 39 inches) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and significant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has significantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion provided more resistance to the forces created by dynamic water and reduces the infiltration of the emulsion into the cracks and fissures of the rockmass. Reduced amounts of oversize and more consistent fragmentation throughout the muckpiles has been a result. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realized. To determine the effectiveness of the oversize reduction project, IOC used a of first-of-kind technology to assess fragmentation presented to the shovel at the digging face. A Digital Vision System (DVS) was installed on one of the shovels to capture images that were stamped with GPS locations. A large population of digital images were analysed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jan 1, 2011

By Nasri Munfah

Long Island Rail Road’s (LIRR) service to New York City is limited to Penn Station on the West Side of Manhattan, which is operating at its practical capacity for the commuter railroad. This situation imposes serious considerations for future growth and limits the destination of many Long Island commuters. The East Side Access Project will provide a connection of the LIRR to the landmark Grand Central Terminal (GCT)on the East Side of Manhattan. The construction of the connection will require significant tunneling and underground work utilizing a variety of construction techniques. In Queens, the connection will require five soft ground tunnels using pressurized face tunnel boring machine. In Manhattan, the connection will require a series of rock tunnels and caverns connecting to two deep large station caverns under GCT to accommodate eight tracks with four platforms in a stacked configuration. The caverns housing train rooms are connected to the lower level of GCT where a large concourse will be provided. With a budget of $4.3 Billion, The East Side Access Project is the largest transportation project ever undertaken in New York City. This paper provides an overview of the project, discusses its environmental and the engineering challenges, and provides an insight into the design development to date.

Jan 1, 2001

By S. K. Das Gupta

The rock laterite was first discovered and described in the State of Kerala, India in 1800 A.D. by Francis Buchanan. It had been used here, and elsewhere in India, for many centuries as a building stone, but in Buchanan's time it was not known that some of these laterites were highly aluminous and could be processed to produce alumina. After World War I India started searching for bauxite reserves with a minimum grade of at least 50% A12O3. By 1960, it was estimated that India had a potential reserve of 245 million tonnes of bauxite, about 10% of which was in the "Proved" category. Subsequent geological exploration now reveals that India has an overall resource of more than 2 billion tonnes of aluminium ore, not all of it bauxite, as defined by earlier geologists. In this paper, the geology, resources and distribution of bauxite and aluminium ore throughout India are described. The generalised stratigraphy, typical laterite and bauxite profiles and summary of the resource position are shown in the attached Tables 1 to 8. It is generally agreed that a tropical to sub-tropical climate, intermittent wet and dry season, good permeability of country rock and suitable drainage, as well as physiographic and ground water conditions are important in the development of bauxite.

Jan 1, 1984

Mineral processes are relatively simple and metallurgical accounting would also be simple if it were not for the nature of the raw materials and the large scale of operations. Essentially the balance between input and output requires only weighing and assaying of the feed, salable products, and waste. but because of complexities to be described in the following pages there are few plants that do not encounter difficulties that cause some sacrifice of precision for economy and practicality. In arriving at a sound compromise, capable

Jan 1, 1985

Table A. Conversion of English to SI Units Table B. Strength Properties of Rocks Table C. Engineering Properties of Rock Table D. Properties of Common Minerals Table E. Material Properties and Characteristics Table F. Heat Value of Various Fuels Table G. Geometrical Relationships and Mensuration Formulas Table H. Standard Sizing and Meshes Table I. Ship Measures Table J. International Atomic Weights Table K. Time Value of Money Factorsfor Discrete Compounding

Jan 1, 2008

By John B. Wright

This paper describes laboratory techniques and subsequent results of Bureau of Mines research to produce chlorination-grade feedstock from an abundant, low-grade, domestic, rock ilmenite ore. The research is part of the Bureau-effort to devise technology that may help decrease U.S. dependence on imported raw materials. A rock ilmenite containing about 46 wt pct Ti02 was smelted in an electric arc furnace with coke, woodchips, and Na2C03 to separate most of the iron as pig iron and to form a low-iron, titanium-enriched slag. The slag was ground, pelletized, oxidized, and then sulfated with mixtures of SO2 and air in a continuous 4.5- to 9.1- kg/h apparatus at 1023 to 1223 K. The sulfated slag, containing 60 to 65 pct TiO2, was reground and leached in water at ambient temperature to decrease the combined levels of the troublesome Ca, Mg, and Mn impurities from 7.0 to 1.7 wt pct. At levels of more than 3 wt pct, these impurities contribute to operating and disposal problems, The final product was upgraded to about 84 wt pct TiO2. This material potentially is suitable for chlorination in a fluidized-bed reactor. The most favorable results were achieved with leached slag sulfated at a feedrate of 4.5 kg/h and at temperatures of 1073 to 1123 K.

Jan 1, 1984

By G. H. Schnakenberg

In 1986, the US Bureau of Mines (USBM) embarked on a major research effort to develop technology that could substantially reduce worker exposure to face hazards by simply relocating the equipment operators to an area of relative safety. This reduced-exposure mining system (REMS) research effort enhances the USBM's ongoing health and safety efforts aimed at reducing and controlling dust and noise and reducing accidents through training and better mining practices. This paper reports on the progress made on the developing research and demonstrates the technologies required for the computer-assisted teleremote operation of continuous mining machines, haulage systems and roof bolting machines.

Jan 1, 1997

By H. Wen

"Taking the long flame coal, gas-fat coal and anthracite as samples, we tested the adsorption quantity to single component gas of N2, CO2 and CH4 under atmospheric pressure phase at different temperatures. Then we analyzed the adsorption characteristics and models of different metamorphic coals. The results show that metamorphic grade, temperature and gases species are main factors to adsorption quantity of coal. The higher and lower metamorphic grade of coal have greatly influence on adsorption capacity while moderate grade of coal has opposite result. The coal adsorption amount to three single component gases under the same experimental condition is CO2> CH4> N2.The simulation precision order of four adsorption models is quadratic curve model > Freundlich isotherm model> Langmuir model >logarithmic curve model. Quadratic curve model and Freundlich isotherm model both can accurately describe the adsorption behaviors of N2 and CH4, different isothermal adsorption curve of CO2 needs two kinds or more models to describe. This has a reference value to the study of adsorption characteristics and models to single component gases.INTRODUCTION Adsorption is the interfacial phenomena that concentration of single or multiple components in the interface layer is different from the bulk phase (1964). Adsorption model is mathematical models to describe the adsorption characteristics of the adsorbent, mainly reflected to fitting effect of gas adsorption isotherm, which contribute to deeply understand the adsorption characteristics of adsorbent. Many scholars have carried out extensively experimental studies of the coal adsorption process from different angles. Zhao (2010) studied the influence of coal metamorphism to pore development of coal seam through a variety of experimental methods. Zhang (2006) analyzed the adsorption capacity and the controlling factors from three aspects of the coal rank, maceral and coal mass deformation. Cheng et al., (2002) studied the influence of pore size distribution of different rank coals to adsorption constants. Zhong (2002) carried out varieties of isothermal assay and established the prediction method of coal seam adsorption affected by a variety of conditions. R. M. Bustin (1998) proposed that we could not simply describe the change law of coal adsorption capacity and maceral content by a fixed parameter, and the adsorption capacity of the same coal rank also has great change. C. R. Clarkson et al., (1997) used four different adsorption models to describe the coal methane adsorption process, and the fitting precision of adsorption models is D-A equation >D-R equation > BET equation> Langmuir equation. Gasem, K et al., (2003) found that the fitted isothermal adsorption curve of D-A equation and BET equation are better than Langmuir equation under high pressure condition, while D-R equation and BET model are better to CO2 adsorption. In recent years, scholars’ at home and abroad research achievements of coal adsorption focused on high-pressure stage (about 0~15 MPa), mainly for coalbed methane exploitation, carbon dioxide trapping and sealing technology development, but the study of coal adsorption under atmospheric pressure phase is little. In this paper, we analyzed the adsorption characteristics and models under atmospheric pressure phase, it has a reference value to the study of characteristics and models to single component gas."

Jan 1, 2015

By Hun-Joon Sohn

Chemical metathesis and electrochemical reductive conversion of chalcopyrite in the presence of cupric ions were studied in sulfuric acid solutions for temperatures up to 90°C. The process results in the displacement of iron in the chalcopyrite lattice by copper ions with rejection of ferrous ions to the aqueous phase. The rate of reaction was found to be very slow, requiring subsieve-sized particles for extensive reaction to occur. The reaction was insensitive to copper ion concentration. Stirred ball milling of chalcopyrite introduces lattice strain. The reaction rate with strained particles was markedly higher than with annealed chalcopyrite. The reaction rate was found to be diffusion-limited, showing two distinct reaction stages corresponding to the formation of CuS (covellite) followed by Cu1.8S (digenite). The experimental activation energy for the first stage was 102 J (24.4 kcal) and the second stage 123 3 (29.4 -kcal) per mole. The rate-controlling process is diffusion of lattice ions, probably iron. The enhanced rate after milling is attributed to a recrystallization process which provides new paths for diffusion along dislocations and grain boundaries.

Jan 1, 1984

By James N. Brentz

This paper deals briefly with the problem of efficiently selecting the most cost effective haulage truck. Problems and factors are identified that effect productivity and operating cost. Despite the sophistication of computerized vehicle simulation programs, there is a wide disparity in accuracy and methodology, particularly in dealing with the various elements of cost.

Jan 1, 1984

By A. Khan

The effect of sulfur dioxide on collectorless and collector induced flotation of chalcopyrite was studied by cyclic voltammetry on a rotating disc electrode. Contact angle measurements were made to determine the effect of sulfur dioxide concentration and electrochemical treatment. The benefits of sulfur dioxide in enhancing the selectivity of separating chalcopyrite from complex sulfide ores are discussed.

Jan 1, 1996

By Nikhil Dhawan, Shrey Agrawal

India’s most extensive renewable energy expansion program targets 280 GW of solar energy by 2030. Due to the massive generation of photovoltaic waste (expected 34,600 T by 2030), stringent recycling effort to recover metal resources from endof- life PVs is required for resource recovery, circular economy, and subsequent reduction in the environmental impact. The present study investigates the recycling potential of end-of-life silicon solar modules. The feed characterization reveals that most of the values in PV modules are concentrated in the frame (pure Al), Si wafer (72–84% Si, 9–12% Al, and 0.13–0.71% Ag), and electrical connections (Cu wire coated with Sn). The Si and Ag values in the feed were beneficiated using water fluidization, and concentrate with 90% Si and 2% Ag was attained in the underflow concentrate. Ag values were recovered in the form of AgCl by leaching in nitric acid and precipitation. After the purification step, the residue containing 99% Si can be further utilized to fabricate Si wafer and Al-Si alloy. The preliminary cost estimations suggest that the proposed process is economically viable for the recycling of solar panels with the maximum value generated from the AgCl precipitate followed by Al panels and Si wafers.

Nov 14, 2022

This chapter contains the edited transcript of the "Gold Heap Leach Information Exchange" session that was held at the 1990 SME/AIME Annual Meeting in Salt Lake City, Utah. The exchange occurred on the afternoon of February 27, 1990. The session was intended to act as a forum for discussing some of the more prominent operating problems associated with heap leaching precious metals. The information exchange was very successful. The exchange consisted of several panelists introducing and discussing different topics, follow by a comment and question period. This transcript contains the panelists' presentations as well as comments and questions from the floor and the panel. Extraneous comments and remarks have been edited out. Some wording has been changed for clarity, but the transcript is basically an accurate account of what was said. At the end of the transcript are two papers submitted as part of the panel discussion

Jan 1, 1990

By R. K. Will

An inactive mining operation in northern California is known to be a source of acid mine drainage and heavy metals which have impacted adjacent creeks. Elevated concentrations of copper and zinc are a concern to aquatic populations, particularly steelhead trout and salmon downstream in the Sacramento River. Previous regional geological surveys of mineralization by the U.S. Geological Survey located and mapped outcrops of massive sulfides and gossan. Recent investigations indicate that a substantial amount of the metals in the local creeks are due to natural causes. The investigations include locating and mapping surface and subsurface minerals, soil and water sampling, and chemical analysis. Groundwater, seeps, and surface water were also sampled and analyzed. A water balance was conducted on a sub-basin level following delineation of surface water drainage and groundwater divides. A chemical mass balance incorporated metal concentrations and water volumes and was then used with other data to determine the contribution of metals from natural versus mining-related causes.

Jan 1, 1998

By S. S. Peng

This paper presents a computer program package for predicting surface movement and deformation caused by under-ground coal extractions. It is capable of: predicting final surface movement and deformation over underground openings; predicting dynamic surface movement and deformation process associated with underground lingual mining operations; processing and bookkeeping subsidence survey data; recommending subsidence parameters for those new coal mines where no subsidence data are available; and deducting subsidence parameters from collected subsidence data.

Jan 1, 1986