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By E. R. Bauer

Previous studies and research efforts have shown that noise-induced hearing loss (NIHL) is a problem in the U.S. mining industry. This is especially true in surface and underground coal and stone mining where large, noisy equipment predominate. Workers in coal preparation and stone processing plants have also been found to be subject to high sound levels that could potentially cause NIHL over prolonged periods of exposure. National Institute for Occupational Safety and Health (NIOSH) researchers have been conducting a cross-sectional survey of equipment noise and worker noise exposures in the mining industry to estimate the potential for NIHL within the mining community. One commodity recently surveyed was the extraction of sand and gravel from surface pits and by river dredging. Little is known about the noise environment and worker exposures in these environments, where processing and mining equipment similar to coal and stone are employed. To address the potential for NIHL in the sand and gravel industry, sound levels on and around the dredges and processing equipment were recorded to identify areas of high noise levels. Full-shift worker dosimetry, in conjunction with task observations, was documented to determine the relationship between exposure and source. This paper presents research examining noise on dredges, in several surface mine sand and gravel operations and in the processing facilities. The locations where workers are likely to be overexposed and were found to be most susceptible to noise overexposures are reported. Results indicate that there are areas on the dredges (crane, suction pumps, and diesel engines) where sound levels greater than 90 dB(A) are present. In addition, crushers and screens used in the processing of the sand and gravel also generate sound levels greater than 90 dB(A). Although no surveyed worker exceeded the Mine Safety and Health Administration (MSHA) Permissible Exposure Level (PEL) of 90 dB(A) TWA8, laborers, mechanics, oilers, helpers, pickers, and greasers are the workers likely to be exposed to hazardous sound levels and thus develop NIHL over time. Knowledge of the equipment noise, area sound levels, and worker dose levels is information that management and employees can use to reduce exposures. Exposures can be reduced in certain areas through administrative controls and through engineering controls applied to the noisiest equipment.

Jan 1, 2008

By H. K. Taylor, B. Denby, L. D. Smith

Contributions by H.K. Taylor and G.A. Davis discuss the three papers published in Transactions IMM A, vols. 103 and 104, with responses by Smith and Dowd

Dec 1, 1995

By Steven E. Mischler, Jay F. Colinet

The study analyzes the impact of the Continuous Personal Dust Monitor (CPDM) on reducing overexposures to coal mine dust. It compares compliance sampling data before and after the implementation of the CPDM and the 2014 MSHA dust rule. The results indicate a significant reduction in the percentage of samples exceeding the dust standard for various mining occupations, highlighting the effectiveness of the CPDM in improving miners’ health and safety.

Feb 22, 2022

By Milner A, Brockway D, Hodges S

The combustion of brown coals in Latrobe Valley power stations produces approximately 500 000 tonnes of solid wastes each year. This material, which includes precipitator ash, char and furnace ash, is hydraulically sluiced to large ashing ponds and the supernatant solution is ultimately discharged to the sea. There are significant operational and capital costs associated with the current ashing system. The ash produced from the Latrobe Valley coals is unique and has a wide variety of potential applications including soil conditioning, concrete and cement extenders, fillers in non-metallic materials, components of building products. In addition, with the application of appropriate technology, it is possible to extract char, sodium sulphate, calcium carbonate and magnesium metal (as the chloride) in substantial quantities from the ash. Research has been carried out to explore the prospects of these various options for ash utilisation. The research has focused on detailed characterisation of the ash material and the potential extraction efficiency for various species under various conditions. From this work a conceptual process has been developed and subsequent studies have been directed towards understanding variables and optimising operating regimes for product extraction. Currently, the work is concentrating on the separation of char, the development of high-grade carbon products and the extraction of sodium sulphate.

Jan 1, 1992

By F. G. Crack, R. V. Ramani, R. L. Frantz

Management for mine construction and development differs from that needed for routine mine production and maintenance. An integrated approach to managing mine development projects must consider contract documents; management organization of a project; the project manager's role and the field supervisor's responsibility; and the use of scientific techniques for planning, scheduling, executing, and controlling projects. Professional project management encompasses the following: • Preparing contract documents that establish technical and financial schedules, and detail the responsibility for the physical work commitment. • Developing a project's organizational structure, to clearly define the roles of the project manager and the field supervisors. • Establishing project management and field supervisor relationships, to avoid ambiguity in assigning responsibility and to ensure desired project progress. • Using management science techniques, particularly networking techniques such as the critical path method for planning scheduling, executing, and controlling projects. Project Versus Production Management Project management differs from routine production management in the following ways: • Uniqueness: A project is unique. Production operations tend to be repetitive. The magnitude of one-time capital expenditures for many facets of mine development warrant special skills and attention. These professional project development skills must already be available by prior experience in the management team. • Personnel: In projects, personnel are usually assigned on a specialty basis and frequently change with the project activity. On the other hand, production personnel work together, more or less permanently. • Management Structure: In a project there may be several staff-line relationships that are not clearly defined and change with changing project activities. In a production situation, the lines of communication and authority are usually well defined. • Time Frame: A difference between project and routine production management is that project activities have comparatively less well defined durations and often tend to be relatively short-term. Production usually has both long-term and short-term plans and well defined long-term and shor-term goals. In project management, formal, critical, short-term reviews are frequently required. In production management, five year plans can be formally adjusted quarterly and annually. Short-term weekly or daily reviews can be informal. • Response to Delays: Delays in a development project may occur without anyone being immediately aware of their existence or suspecting the magnitude of consequence. In contrast, any delays in the production process can be easily identified from prior results comparison. Additionally, the response is quick, usually in a set routine. This can be traced back to the management structure and personnel. • Control Techniques: Measurements of project progress for control are not easily made due to the variety of activities that are carried on at the same time by different work groups. The yard-sticks of performance measurement for individual activities, let alone for the total project, are not easily established. However, due to the difficulty in detecting project delays, a workable control system is vitally important to a project manager. To apply a scientific project control technique such as "management by exception" requires specific planning and monitoring from the project manager for each activity in the project. Production and productivity are quick and effective yard-sticks of measuring performance in a routine operation. Control techniques required in production management usually revolve around these measures. Construction Contracts The construction contract is an important document that establishes contract scope, technical and financial details of the work, and achievement deadlines. It may also serve as the contract document to pay for work done and to verify field progress with planned progress. In practice, it is a good idea to develop a job-specific contract. This whole area is replete with legal precedence and procedures, and it is not the intent here to deal with the intricacies of establishing a contract document. But it is necessary to have an understanding of major contract types. Construction contracts are extremely important legal documents. They may vary in work specifications and enforcement of the provisions. Due to their nature, they must be composed with legal help and will take some time to compile. Even with all the precautions and provisions, it is not uncommon to find owner and contractor disagreeing. Therefore, it is important to include a way to resolve any difference quickly and to incorporate aspects of the contract as part of an overall management control tool for efficient project management.

Jan 7, 1982

A direct comparison has been undertaken between laboratory wind tunnel experimentation and computational fluid dynamics simulation of a 3D manufactured analogue for a body of fractured broken rock, created with CAD/CAM techniques. Detailed descriptions of the ?design? of the analogue (using a discrete element analysis multi-body simulator), its manufacture (using computer aided design and 3D printing technology) and the laboratory experimentation (inserting the physical analogue into a laboratory scale wind tunnel) are presented. The agreement of the results of direct experimental observations on the manufactured analogue with the values from CFD simulations of those experiments justifies the utilization of a CFD environment for the practical investigation of geometric factors controlling air flow and heat exchange in complex assemblages of broken rock blocks. The ultimate goal is described, that of developing functional relations between bulk properties of such assemblages (such as their porosity and bulk density) and the low-level geometric factors that dictate the air flow behaviour, such as the equivalent perimeter length of the cross-sectional area available for flow, or average flow path tortuosity. A practical application area of the work in the mining context is also described; equivalent continuum air flow and heat transfer constitutive models developed on the CFD tool from such functional relations are useful in characterization of seasonal heat storage in large scale bodies (approximately 1 km3) of broken rock.

Aug 1, 2013

A substantial proportion of current and historic West Coast gold production comes from deposits situated around the margins of æice ageÆ glaciers. Gold has been eroded and transported by glacial ice then deposited in till and outwash gravel. The interplay between fluvial and glacial processes, climate, basement geology, tectonic uplift, sediment supply and sea level dictates many aspects of the development of the West Coast landscape. The way in which the external forcing factors interact is crucial in determining the gold content of placer deposits in this region. The following is an outline of some of the factors that influence the gold distribution in vicinity of glacial margins.

Jan 1, 2000

By Ü. Atalay, G. Alaeddinoglu, G. Özcengiz, G. Özbayoglu, Z. Özdemir

In this study, bacterial pre-treatment was applied before cyanidation in order to enhance the solubilization of silver from Artvin-Kafkasör ore Direct cyanidation process was found inefficient to recover silver from the ore. Only 40.36% silver recovery was obtained with direct cyanidation while silver recoveries of above 60% were obtained after bacterial treatment. Thiobacillus ferrooxidans was used as the microorganism in pretreatment tests. Effects of various parameters such as pulp density, duration, inoculum size and particle size on silver recovery have been investigated in this study.

Jan 1, 2001

By Kenneth Eltschlager

Business says that location is a primary component of being successful. So too is the importance of location in blasting. For blast seismograph data to be useful, the location of the blast and seismograph must be clearly documented. Another location of importance is that of a nearby structure. Establishing the spatial relationships between the blast, seismograph and nearby structures, allows the blaster to correctly interpret the data, evaluate the performance of the blast and gauge the validity of any complaints.

Jan 1, 2004

By Doris M. Hyde

Mineral output and trade in the Central American countries were directly or indirectly affected by the sometimes violent civil unrest and recessionary economic developments that have pervaded the region for several years. Central American countries found their foreign exchange export earnings and traditional market areas shrinking while essential import costs were rising. Restricted spending measures were adopted by governments and private industries. Domestic investment funds for mineral development and exploration projects were among the first casualties of these austere budgetary measures, especially since weak demand and depressed mineral prices diminished the probability of a favorable cost-benefit ratio. The lack of physical security and political stability also discouraged private foreign investment. The United States Congress enacted the Caribbean Basin Economic Recovery Act of 1983 (19 U.S.C. 2702), more popularly known as the Caribbean Basin Initiative (CBI). This legislation was designed to stimulate economic recovery and promote economic development by increasing private investment and trade in the Caribbean Basin countries. The act provided for the elimination of U.S. duties on most trade items imported directly from eligible Caribbean countries, provided at least 35% of the product value originated in the region. The financial assistance components of the CBI were to be supportive of the basin's private sector as well as assist general economic stabilization programs.

Jan 1, 1985

By Brian Khalighi, Massimo Franceschi, Giovanni Giacomin, Gianni Porta

Headrace Tunnels and parts of the Access Adit Tunnels of Kárahnjúkar Hydropower project, KAR-14, in Iceland will be excavated using three full-face Robbins Tunnel Boring Machines (TBM). TBM sizes range from 7.23 to 7.63 meters in diameter and the total headrace tunnel length is approximately 40 km. The crushed rock is transported on conveyor belts to disposal areas near each Adit. The estimated average excavation rate is approximately 25 meters per day per machine. Electricity will begin to flow in April 2007, and the project is scheduled for completion in 2009. This paper is divided into four sections. In the PROJECT OVERVIEW section, a short overview of the scope of the project is presented. In the GEOLOGY section, the geological condition along the tunnel drives is briefly introduced. The TBM DESIGN section discusses the various design criteria and the resulting machine specifications. The paper concludes in the TBM OPERATION section with a case history describing the tunneling operation from start-up to the time of the writing of this paper.

Jan 1, 2005

By René de Batz

From 1754 to the end of 1895 the production of gold in Russia had been approximately as follows: Kilogrammes. Russia proper (Finland and the Caucasus),. .. 890 The Ural Region,........505,386 Western Siberia,........116,937 Eastern Siberia,........1,218,372 Total,.........1,841,085 of the value of more than $1,200,000,000.

Jan 1, 1899

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 Brian P. Waagner

Construction law in general and the law of deep foundations in particular continues to develop rapidly, particularly in the areas of risk allocation. Public and private owners are increasingly using contractual disclaimers to shift the risk of differing site conditions to contractors, and courts are increasingly willing to enforce these contractual devices. Perhaps also in an effort to control costs, public and private owners are turning to design-build contracting techniques. While design-build offers many advantages over traditional project delivery systems, it does not answer all of the risk-allocation questions that frequently arise. Even in design-build, problems with unanticipated subsurface conditions and defective design are not easily addressed. Finally, developments in electronic commerce present the potential to transform the construction industry.

Jan 1, 2002

A comparatively new and very promIsmg field for applying cemented tungsten-carbides is in the mining and quarrying industries. The economic advantages of this unique engineering material over the conventional hollow drill steel, or steel detachable bits, have proven so great that the use of "hard metals" promises, in some instances, to revolutionise the drilling of all manner of minerals. Early in the war years the Germans realised the tremendous advantages cemented carbides offered for holing hard rocks, and they proceeded to develop detachable percussion bits to do this work, at the same time evolving fast, comparatively light-hitting driliing machines, especially designed to suit the mechanical properties of the carbide.Here in Australia also, it has appeared that the detachable percussion bit offers the greatest economic benefits to consumers, although the author is well aware that carbide-tipped drill rods have, and may continue to work out satisfactorily in certain mines and quarries.Most drilling equipment at present installed in Australia may be described as being of the heavy hard-hitting variety, so that the designer of an efficient percussion bit has to take special precautions to overcome the problem of fatigue, and to ensure that the inserts are securely mounted in the body with the minimum of internal stress in the carbide.

Jan 1, 1950

By O. T. Rämö, E. Suikkanen

Episyenites are sub-solidus, quartz-depleted alkali-feldspar-rich rocks. They form veins and lenticular bodies in granitoid rocks and migmatites in a late- to post-orogenic or anorogenic setting. Leaching of quartz is usually a response to a flux of weakly saline hydrothermal solution in circulation cells above cooling intrusions, where sufficient fluid-rock ratios and thermal gradients are achieved. Fluid Si-undersaturation is achieved by rapid cooling within the field of retrograde Si solubility or by temperature and pressure increase outside retrograde conditions. Some quartz may also be consumed in metasomatic reactions and in response to pressure fluctuation in sealed episyenite bodies. The small size and overall rarity of episyenites imply that conditions for episyenite formation are not commonly encountered in the crust. In addition to quartz depletion, episyenites record complex histories of metasomatic alteration and hydrothermal mineral growth. Nearly all episyenites have undergone Na-metasomatism, which may have led to the formation of nearly monomineralic albitite, and which is occasionally followed by late K-metasomatism, phyllic alteration, and argillization. Depending on the effectiveness of later compaction, recrystallization and vug-filling episyenites may preserve the macroscopic porosity formed by quartz dissolution and brittle deformation. Vuggy episyenites can act as significant sinks for metals carried by crustal fluids and host many significant U, Sn, and Au deposits worldwide. Rare earth-critical syenitic fenites around alkaline intrusions share mineralogical and genetic traits with episyenites.

By O. T. Rämö, E. Suikkanen

Episyenites are sub-solidus, quartz-depleted alkali-feldspar-rich rocks. They form veins and lenticular bodies in granitoid rocks and migmatites in a late- to post-orogenic or anorogenic setting. Leaching of quartz is usually a response to a flux of weakly saline hydrothermal solution in circulation cells above cooling intrusions, where sufficient fluid-rock ratios and thermal gradients are achieved. Fluid Si-undersaturation is achieved by rapid cooling within the field of retrograde Si solubility or by temperature and pressure increase outside retrograde conditions. Some quartz may also be consumed in metasomatic reactions and in response to pressure fluctuation in sealed episyenite bodies. The small size and overall rarity of episyenites imply that conditions for episyenite formation are not commonly encountered in the crust. In addition to quartz depletion, episyenites record complex histories of metasomatic alteration and hydrothermal mineral growth. Nearly all episyenites have undergone Na-metasomatism, which may have led to the formation of nearly monomineralic albitite, and which is occasionally followed by late K-metasomatism, phyllic alteration, and argillization. Depending on the effectiveness of later compaction, recrystallization and vug-filling episyenites may preserve the macroscopic porosity formed by quartz dissolution and brittle deformation. Vuggy episyenites can act as significant sinks for metals carried by crustal fluids and host many significant U, Sn, and Au deposits worldwide. Rare earth-critical syenitic fenites around alkaline intrusions share mineralogical and genetic traits with episyenites.

By Murray Pearson, Jack Murray

"The danger of autoclaves lies in the high temperatures and pressures that exist in autoclave vessels. The usage of autoclaves will continue to expand in the mining industry because of their efficiency and environmental friendliness. But increasing attention must be paid to ensuring their safety. Safety Instrumented Systems (SISs) play a critical role in autoclave plants by detecting potentially dangerous conditions, taking the plant to a safe state, informing the operator about the plant status and the cause of the trip and expediting safe plant restart. The SIS should ideally be fully integrated with but functionally independent of the Basic Process Control System (BPCS) and provide redundant logic solvers to increase safety and plant availability while reducing spurious trips.INTRODUCTIONWikipedia defines an autoclave as follows: “An autoclave is a pressurized device invented by Charles Chamberland in 1879 designed to heat aqueous solutions above their boiling point to process materials.” A typical autoclave system used in the metallurgical industry includes, besides the autoclave vessel, heat recovery (heater) vessels, high pressure positive displacement (HPPD) feed pumps, vessel lining systems, specialized internals and components, agitators, pressure letdown or flash vessels, isolation and control valves, over 2,000 I/O points and related instrumentation, and emergency relief systems."

Jan 1, 2009

Most analysts determining tungsten trioxide in low grade samples are aware that colorimetric procedures do not possess the inherent disadvantages of gravimetric methods operating on milligram quantities of tungsten trioxide. Apart from the inaccuracies associated with weighing four or five milligrams of ignited oxide in a platinum crucible of about 30 gm. weight with a large surface area to absorb moisture, using a 5 gm. charge on samples less than about 0·15 per cent tungsten trioxide, it is extremely difficult toget complete or pure precipitation of tungsten with cinchonine, cinchonine plus alpha benzoin oxime, rhodamine B or any other of the commonly used precipitants. Table 2', No. 8, illustrates the low results obtained by gravimetric as opposed to colorimetric procedures. In addition the colorimetric determination requires only a small portion of the time consumed by gravimetric practices and the increased accuracy obtainable in low ranges together with the saving in time made it highly desirable to develop a colorimetric method suitable for King Island ores.The most commonly used colorimetric method is that introduced by Feigl and Krumholz (1932), since modified by various investigators (Grimaldi and North, 1943; Sandell, 1946; Westwood and Mayer, 1947; Gentry and Sherrington, 1948; Freund, Wright and Brookshier, 1951; Grouthamel and Johnson, 1954; and others). Stannous chloride is used to reduce tungsten followed by colour development with a thiocyanate, usually sodium, potassium or ammonium.Other reducing agents have been proposed (Emery and Curtis, 1948), but only in recent years have the conditions governing maximum colour development been fully estab...

Jan 1, 1958

Geochemical data on Australian granites and pegmatites, and the mineral components of these rocks, are compared with that obtained in similar studies in the U.S.S.R. and elsewhere.The geochemical character of tin granites and the trace chemistry of their component minerals, particularly biotites, have some significance as ore guides in prospecting for tin.The primary geochemical dispersion of tin can be readily tested both in the laboratory and field by colourimetric methods, after volatilization with ammonium iodide, using modifications of the method described by Wood (1958).Secondary dispersions of tin in residual soils or alluvia can likewise be readly tested by rapid colourimetric methods in the field, but simple hydraulic methods, handling larger sample volumes, give reliable outlines of dispersion patterns.INTRODUCTIONThe search for tin ores, whether lode or placer in type, is usually directed on genetic grounds to country within or adjoining acid intrusives.A long established means of prospecting is to test samples for cassiterite by panning or other hydraulic separation.These methods can be used on crushed lode material or the natural materials from placers.With the advent of new techniques for extraction and for colourimetric analysis for tin (Wood, 1958 and Ross and White, 1961) a means is available for rapid analysis of materials not susceptible to quantitative testing by hydraulic methods because of the fine sizings of cassiterite or the occurrence of tin structurally held in minerals. The new methods thus opened up the field of tin prospecting by extending the search for ore guides to genetically associated rocks and minerals, wall ror-ks of veins and a wider range of superficial deposits.

Jan 1, 1963