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By Howard E. Mitchell

Modern mechanical raise drilling was first introduced into the United states in 1962. This method of safely, economically raising a shaft has steadily increased in popularity since that time. This steady growth has been largely enhanced by the many advantages to be gained by mechanical raise drilling, as well as by the increasing reliability of the equipment required. It is the purpose of this paper to briefly review the state of the art of raise drilling to include: the various applications and advantages; the equipment requirements, including a comparison of the various types and sizes of machines and rock cutting equipment; equipment performance; and future trends.

Jan 1, 1978

By Denis Yeung

In an effort to find better ways to dispose of potentially toxic material, the effect of longitudinal and lateral dispersion on the dilution of toxic fluids was investigated numerically and experimentally. Homogeneous and non- homogeneous tests were conducted to model this effect for surface mine backfills. These tests used a high-density zone [package] to bury undesirable material. The studies, utilizing inert tracers, showed that an increase in density in a soil will decrease the maximum level of tracer in the discharge. Within the range of experiments performed and using only natural materials, a 65 percent reduction in peak concentration was obtained.

Jan 1, 1982

By J. E. Feddock

To succeed in today's competitive coal market, coal companies must continuously improve production and lower cost. However, the coal industry's historical management practices must change to remain viable? The practices of the current day efficient coal mine manager are reviewed and examined using W. Edwards Deming's definition of management. The statistical tools, including Pareto Charts, Control Charts and Scatter Diagrams, which identify the problems management must approach differently to increase productivity at a coal mine, are discussed.

Jan 1, 1993

By Serge Payant, Michael G. Li, Lionel J. J. Catalan

Alkaline solution rinsing for decommissioning of an acid-leached residue was evaluated by column experiments, neutralization tests and solid characterization by XRD and SEM. It was found that consumption of a strong alkali during residue neutralization was much greater than that required to neutralize the soluble acidity. The excess alkalinity was consumed by solid-phase conversions unnecessary for the success of decommissioning. Alkaline rinsing did not reduce the time requirement for decommissioning when compared with plain water rinsing. Since no benefit is gained to compensate for the additional costs associated with excess alkali consumption, we conclude that strong alkaline solution rinsing is in fact inferior to simple water rinsing.

Jan 1, 1998

By Lee Ann Arrington-Webb

Thiele Kaolin Co. has invested much time and money in achieving and maintaining its IS0 9002 certification. Through a regimen of process control and documentation, routine audits and a commitment to quality management, this kaolin producer is a competitive pigment supplier in a worldwide market. Background In 1987, the International Organization for Standards developed the ISO 9000 quality management system. This series of standards is used as a means to ensure customers that a quality management system is in place. Certification of a company does not mean that an individual product is of high quality. Rather, it demonstrates a supplier's ability to meet its customers' product and service needs. It also shows that a company has documented records to assure product consistency. The ISO 9000 system was begun in England during the early 1980s. During the mid-1970s, the British manufacturing industry was experiencing low quality. In an attempt to boost quality standards, the British government established the BS 5750 standards system. In 1987, BS 5750 was incorporated into ISO 9000. The ISO 9000 series consists of three levels of certification. ISO 9001 is the model for quality assurance in "design/development, production, installation and servicing." This standard applies to companies that rely on research and development to bring products that frequently change to market. ISO 9002 involves "production and installation" only. This standard is relevant to industries that produce a specific product according to specifications - either their own or their customer's. ISO 9003 is the model in "final inspection and test." This standard is the least detailed of the 9000 series. It is also the most applicable to companies that purchase, inspect or sort and resell. The quality system requirements for certification are outlined in the 18 elements of ISO 9002. These include: 4.1 - Management responsibility. 4.2 - Quality systems. 4.3 - Contract review. 4.4 - Design control. 4.5 - Document and data control. 4.6 - Purchasing. 4.7 - Control of customer-supplied product. 4.8 - Product identification and traceability. 4.9 - Process control. 4.10 - Inspection and testing. 4.11- Control of inspection, measuring and test equipment. 4.12 - Inspection and test status. 4.13 - Control of nonconforming product. 4.14 - Corrective and preventive action. 4.15 - Handling, storage, packaging, preservation and delivery. 4.16 - Control of quality records. 4.17 - Internal quality audits. 4.18 -Training. Continuous improvement, though implied in maintaining these requirements, could potentially be included in the quality system requirements in the next revision. The ISO 9000 requirements and documentation system is shown in the hierarchy pyramid (Fig. 1). A company's quality policy serves as the top of the pyra-

Jan 1, 1997

By K. J. Stanaway

Concentrations of minerals between 3.5 and 5 specific gravity such as ilmenite, rutile and zircon in large accumulations of sand constitute "heavy mineral" placers. Two fundamentally different modes of formation characterize "trap" and "bed" placer variants. Smaller and generally higher grade trap placers form during sediment erosion or reworking. Because of their smaller size, they rarely yield economic heavy mineral deposits. They become economic, either if they contain more valuable "heavies" such as gold, or, if they occur within or near much larger but lower grade bed placers. Bed placers form during sediment accumulation episodes in any environment and lithofacies where mineral supply and fluid dynamics are favorable. Three heavy mineral deposits are discussed to illustrate bed placer geology and how trap placers occur with and relate to them.

Jan 1, 1991

By W. E. Lindquist

Roasting of refractory gold ores has the primary goal of oxidizing sulfides and organics to improve gold recoveries prior to leaching. Commercial installations currently utilize bubbling and circulating fluidized beds. The principle of flash roasting is aimed at a more cost effective method of whole ore roasting for large throughput applications. Results of pilot plant testing and scale up to commercial design will be discussed in further detail in this paper.

Jan 1, 1993

By G. M. Li

It is shown that seriously preoxidized arsenopyrite can adsorb a large amount of copper ions as unoxidized one, but without, release of corresponding amount of Fe ions; seriously preoxidized pyrite cannot adsorb copper ions, but with release of a large amount of Fe ions. However, if the minerals are rapidly oxidized with potassium permanganate solution, both arsenopyrite and especially pyrite can adsorb a large amount of copper ions, but still without release of corresponding amount, of Fe ions. Cu adsorption (if there is any) on both oxidized arsenopyrite and pyrite is not based on the Cu-Fe exchange mechanism.

Jan 1, 1991

The effects of additives, sodium hydroxide, sodium carbonate, sodium oleate, oleic acid and polyacrylic acid, on stirred media milling of limestone have been investigated. The results are evaluated in terms of specific surface area, specific energy and energy efficiency as a function of additive dosage, polymer molecular weight, solids concentration and relevant operating variables. Use of additives generally results in changes in specific surface area and energy efficiency, while under certain conditions a more than 100% increase in these parameters can occur. Relevant interfacial properties have been measured and milling mechanisms involved are explored particularly in terms of the effect of additives on the flow patterns at higher solids concentration.

Jan 1, 1996

By Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Mine explosions are one of the most concerning risks related to underground coal mining, as a single gas explosion can cause injuries and fatalities among miners. Underground infrastructure seals and build-in-place (BIP) refuge alternatives (RAs) are employed to isolate an area from active workings to mitigate coal mining-related accident risks. They are designed to withstand blast pressures from a possible accidental detonation of the contained gas or a coal dust explosion. Crosscut seals and BIP RAs, typically consisting of steel-reinforced concrete, are prone to strong convergence and have a significant leakage potential due to high convergence damage near mined-out areas. The roof-to-floor convergence can change the structural integrity of these structures, and altered structural integrity can lead to less explosion resistance capability. Hence, a thorough analysis is needed to further understand their explosion response under various strata conditions.

Jul 1, 2023

By J. MCGUIRE, E. J. Haas, B. Demich

Near misses can enhance awareness of the potential causes of injury and prompt safety management initiatives. Although most companies require near-miss reporting, the value of these reports and how they influence subsequent actions or controls to reduce on-the-job risks are unclear. Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted a case study with an aggregates company in which near-miss reports were analyzed at each of their locations over an entire quarter during the summer of 2018. Within that quarter, workers recorded 249 near misses. The analysis provides insight into ways that risk-communication and management programs can be improved to reengage workers and their situational awareness on the job.

By C. J. Bise

In August, 1977, the Federal Surface Mining Control and Reclamation Act was signed into law [I]. It stated that: "The Congress finds and declares that because of the diversity in terrain ... and other physical conditions in areas subject to min ing operations, the primary governmental res- ponsibility for developing, authorizing, issuing, and enforcing regulations for-surface mining and reclamation operations subject to the Act should rest with the States." Section 516 of Title V (Control of the Environ mental Impacts of Surface Coal Mining) of the Act deals with the surface effects of underground coal mining operations. "Each permit issued under any approved State or Federal program pursuant to this Act and relating to underground coal mining shall re quire tfieoperator to adopt izeasures consist ent with known technology in order to prevent subsidence, causing material damage, to the extent technologically and economically feasible, maximize mine stability, and main tain the value and reasonable foreseeable use of such surface lands, except in those instances vhere the mining technology used requires planned subsidence in a predictable and controlled manner: Provided, that nothing in this subsection shall be construed to prohibit the standard method of room and pillar mining. "

Jan 1, 1980

By Q. Xu

Adsorption of nonionic/anionic surfactant mixtures on kaolinite has been studied with sodium dodecylsulfate as the anionic surfactant and octaethyleneglycol mono-n-dodecylether as the nonionic surfactant. Synergistic interaction between these surfactant was found to cause adsorption of the nonionic surfactant with its hydrophilic chains protruding into the bulk, leading to substantial changes in wettability and dispersion characteristics of kaolinite. Similarly, hydrophobicity changes are observed also for silica particles upon adsorption of nonionic ethoxylated alcohols owing to possible changes in the orientation of the adsorbed surfactant molecules at the interface.

Jan 1, 1991

The floatability of a bituminous coal in NaG solutions was evaluated using a modified Hallimond tube to delineate the role of the electrostatic interaction between bubbles and particles in determining the coal hydrophobicity. Zeta potential measurements showed that bubbles are negatively charged in the entire pH range tested, while coal particles are positively charged below pH 6.0 and negatively charged above it. Also, both sodium and chloride ions were confirmed to act as indifferent ions without any specific effects for both coal particles and bubbles. Flotation as a function of pH exhibited a maximum and minimum at low salt concentrations which is shown to be determined mainly by the coal hydrophobicity as measured by a new hydrophobic levitation technique. At high salt concentrations (above 0.1 mole/dm3), the flotation without such maximum or minimum is controlled by the electrostatic interaction between the bubble and the particle.

Jan 1, 1992

By Steven Hoerger

Mixed integer linear programming (MILP) production scheduling models can be used to evaluate if tonnage improvement projects will deliver value over all time periods and whether new bottlenecks will be created. These MILP models can evaluate the interconnected effects of mine and process capacities, mining locations, cutoff grades, stockpiles, and orebody grade/tonnage distributions. A case study compares potential value creation from a mine capacity increase, a mill capacity increase, or a simultaneous increase in all capacities. For perspective, project valuations for capacity increases are compared against valuations for cost reduction projects, mine planning improvements such as phase design, dynamic cutoff grades and stockpiling, and the impact of geostatistics improvements in the areas of block model accuracy and ore control selectivity.

Feb 1, 2024

By R. L. Weigel

As Florida phosphate mining gradually moves from the Bone Valley formation to the Hawthorn formation, a greater portion of the minable deposit contains dolomitic diluents which result in lower product grades that can be detrimental to the production of phosphoric acid for fertilizer uses. One beneficiation technique found applicable to the phosphate pebble size range (3 X 16 mesh) is heavy media separation using suspensions of magnetite and ferrosilicon. As part of an ongoing investigation of dolomite removal technology, a pilot heavy media cyclone system was constructed by IMC and used in the testing of a variety of drill core composites and hulk samples. The results of these tests were used to develop a predictive model for heavy media cyclone separation based on pebble fraction assays and heavy media operating parameters. This model is currently being used in the evaluation of specific future mining areas.

Jan 1, 1984

By J. P. Rider

Along with increased production from longwall units has come the likelihood of increased worker noise exposures. In recent years, equipment has become larger, more powerful, and noisier than its predecessors. For these reasons, the Mining Division of the National Institute for Occupational Safety and Health (NIOSH) is investigating worker noise exposure on longwall faces and researching possible solutions to reduce this exposure. Part of this research effort involves studying the effect of covering the underside of longwall shields with acoustical material to reduce reverberating noise along the face. Experiments using acoustical absorptive insulation to cover the undersides of the shields, shearer body, and the shield supports were conducted at the full scale simulated longwall test facility located at the Pittsburgh Research Center. Sound levels were recorded every l.5 m [5 ft] along a 15.2 m [50 ft] section of the simulated face for all of the conditions tested. The analysis of the data indicated that a 2.0-3.0 dBA noise reduction was achieved between the shearer drums and a 4.0-5.5 dBA attenuation was attained upwind of the headgate drum.

Jan 1, 1997

By R. A. Bauer

Investigations of bedrock within subsided areas over abandoned coal mines in Illinois reveal very little disturbance of the bedrock. In areas that have surface subsidence of 0.3 to 1 m (1 to 3.25 ft), examination of cores from exploration drilling and investigations of the boreholes by means of closed circuit television have shown that fractures are spaced at least 0.9 to 3.6 m (3 to 12 ft) apart. They are located within a zone 6 to 15 m (20 to 50 ft) above the collapsed area in coal mines 42.6 to 112.7 m (140 to 370 ft) deep. The dip of the fractures ranges from 25° to 60°, cutting across nearly horizontal sedimentary bedding planes. The amount of fracturing found in the collapsed area decreased as the amount of soft, weak materials increased in the immediate overburden of the mine.

Jan 1, 1987

By S. C. Schmelter

The destabilizing effect of water pressure on rock mass stability is examined quantitatively by the finite element method. A coupled code that accounts for the simultaneous effects of rock mass deformation and transient fluid flow is used for this purpose. The traditional soil mechanics assumption of an incompressible fluid is shown to be untenable for the analysis of porous, fractured rock slopes. A Mandel-Cryer effect, a transitory but elevated and potentially destabilizing water pressure following a cut, was not observed.

Jan 1, 1997

By H. Wesley Peirce

Arizona, in 1966, has continued to be the site of an extensive and intensive search for metallic mineral deposits. Over fifty separate entities--companies and individuals--have been actively engaged in mineral exploration programs, both large and small, in the Basin-and-Range portion of the State. Certainly, copper has been primarily responsible for the major efforts, although associated gold, silver, and molybdenum mineralization also has been important in the economic evaluation of potential copper deposits. It is not difficult to explain why the Basin-Range portion of Arizona is receiving such attention. Part of the story, undoubtedly familiar to most, can be illustrated by reference to three graphical presentations. For example, Figure 1 shows Arizona's annual copper production for the period 1955-1965, inclusive, and it demonstrates that new records of production have been accomplished in each of the past 6 years and in 9 of the last 11 years.

Jan 1, 1967