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A compilation of papers presented at the Fifth WVU Conference on Coal Mine Electrotechnology in Morgantown, West Virginia, on July 30, 31, and August 1, 1980. Papers cover areas of electromagnetics/power systems, power systems, monitoring and control, and communications.

Jan 1, 1980

By M. Zanini, D. Wong

ABSTRACT: Metals market improvements in 2005 drove the desire to increase nickel throughput and the production of nickel oxide sinter at the Vale Ltd. Copper Cliff smelter. Significant difficulties were encountered due to the unreliable quality of Bessemer matte being produced. Concentrate feed changes and the loss of technical and operational expertise during the previous market downturn contributed to the challenge of making the required improvements. Significant progress has been made in the converter aisle by focusing on employee engagement and standardizing best operating practices for a new generation of skimmers. This paper documents these initiatives and seeks to balance the art and science of converting.

Jan 1, 2012

By Russell C. Frith

This paper examines the design of longwall shields, focusing on those aspects that are critical to either their successful application or contribution to failure during longwall extraction. In many instances, longwall shields are assessed and designed along lines similar to that of roadway ground support systems, namely according to typical or normal geotechnical conditions. However it will be contended that for longwall shields, this is inappropriate because unlike roadway ground support systems, longwall shields cannot be supplemented with additional or secondary support in localised areas of adverse geotechnical conditions. In other words, the longwall shield needs to be designed according to what are judged to be worst case or adverse geotechnical conditions?the outcome being that a well-designed shield will be significantly over-rated for the majority of its working life. Therefore, it will be argued that the additional capital cost of such shield design can be readily justified as a prudent riskbased outcome that is essential to minimising future business risks due to strata instability on the longwall face. Shield geometry will be discussed, including such relevant factors as leg angle, inclination of the top caving shield, canopy ratio, operating height range, and tip to face distance. These are all well-established longwall shield design considerations and, most importantly, areas whereby inadequate design can render a longwall shield as highly ineffective. The issue of tip to face distance will be considered in detail, in particular, the extent by which it is an important geotechnical design consideration, the conclusion being reached that, in fact, it is not. The critical importance of maximising set to yield ratio within practical operating limits will be justified, the wisdom of this having been subject to questioning in more recent technical literature. Overall, the aim is to provide the industry with a set of suggested guidelines for future use when designing longwall shields and, hopefully, to initiate discussion on a subject that, unlike roadway ground support design, is not well covered in its entirety in the published technical literature.

Jan 1, 2013

By A. De1

Because of the extremely low utilization of strain energy in the breakage of solid particles, the energy efficiency prevalent in comminution technology is extremely poor. Schoenert considered that single-particle comminution under slow compression is the most energy-efficient mode of comminution and that energy efficiency should be compared to that. The usual method for grinding minerals and cement has been the ball mill, in which the hit-and-miss aspect of loose-bed comminution severely reduces energy efficiency. The fine grinding of minerals is a particularly energy-intensive process. Schoenert showed that the energy consumed in the comminution of particles in confined beds is second only to that of single-particle comminution under slow compression and developed the method of conducting particle-bed comminution continuously in a high-pressure roll mill. Since its first industrial installation in 1985, the high-pressure roll mill has established itself as the comminution device of choice for significantly improving the productivity and energy efficiency of size reduction from coarse size feeds down to products finer than 20 microns. The first of several hundred installations were in cement plants. The preliminary design and optimization of the industrial operation of high-pressure grinding roll (HPGR) systems, owing to the continuous nature of the device, cannot be efficiently done through laboratory experiments and needs to be achieved through proper system modeling. While the energetics of size reduction in high-pressure grinding rolls has been modeled very well, no model exists for the macroscopic variables in HPGR comminution. In high-pressure roll mill grinding, size reduction results from confined particle-bed comminution under compressive stresses such that the daughter particles produced are highly fractured, stressed, or otherwise weakened. This paper attempts to relate the comminution / compaction behavior for confined particle-bed under compression in a piston-die press with the macroscopic variables in HPGR comminution. A model describing the pressure-densification relationship is presented and used to accurately simulate the macroscopic variables in high-pressure grinding rolls, utilizing experimental data for particle-bed comminution with the piston-die press. The accuracy of the predictive simulations strongly suggests that, starting with a few batch-mode laboratory-scale experiments, it should be possible not only to identify the optimal operating conditions for existing operations but also to successfully design new industrial high- pressure grinding roll systems.

Sep 1, 2012

The objectives of mining grade control are presented and examples of the techniques used in various open pit and underground mines are used to define the attributes of good grade control. Reasons are discussed for the success of various improved practices. The progressive development of grade control is presented and the balance between quantitative and qualitative data is analysed. The skills and resources required for grade control on mine sites that are using best practice are also presented. A number of problems in grade control have been solved recently however there are still issues that need to be addressed. Examination of the grade control process frequently stops after sample quality has been examined. There is much more beyond this that can now be optimised using conditional simulation models. Other future directions of mining grade control are also suggested. An extensive bibliography of published papers on grade control is included that will be maintained and updated on a website.

Jan 1, 2000

By R. H. Fernald

In 1900, as far as available records show, there were only two producer-gas power installations in the United States. In June, 1915, the number probably exceeded 1,000. Of this number, some 84.5 per cent comprised small plants using anthracite, and only about 15 per cent of the total number utilized bituminous coal and lignite. In addition to these, two plants used wood, and three or four used oil. In the main, however, the larger sized units are operating on bituminous coal and lignite. During the early years of these plants little success was anticipated from the use of bituminous coals and lignites, but in 1904 and 1905 it was fully demonstrated at the Government testing station at St. Louis that these fuels could be utilized to excellent advantage. However, although many producer-gas plants in daily operation are using bituminous coal and lignite, many power-plant men are still skeptical regarding the successful commercial use of these fuels.

Jan 1, 1916

By D. G. Willard

The U.S. Department of Interior, Bureau of Mines has evaluated the potential resource and annual availability of cobalt from 27 deposits or districts in 11 market-economy countries. More than 95 pct of primary cobalt production from market-economy countries, mainly byproduct output from copper and nickel operations, was analyzed. Approximately 1,200,000 mt of cobalt is potentially recoverable at the demonstrated resource level. Very large additional resources exist, especially in laterite deposits, but are at the inferred level. The producing operations evaluated in this study are expected to produce about 19,000 mt of cobalt in 1989, significantly less than the available capacity of about 31,000 mt. More than 14,000 mt per year of cobalt is produced from copper-cobalt deposits in Zaire and Zambia, of which 11,000 mt can be produced at a copper price of $O.60jlb or less with a O-pct discounted cash-flow rate of return (DCFROR). Approximately 4,400 mt of cobalt is produced annually from nickel-cobalt deposits in six countries, of which about 1,800 mt (in Canada and Brazil) could be produced at a nickel price of $1.50jlb or less at a D-pct DCFROR. Approximately 200 mt per year of cobalt is produced from a cobalt mine in Morocco. Most of the evaluated nonproducing operations and prospects that could potentially produce cobalt as a principal product or byproduct would require a total cost (including a 15 pct-DCFROR) significantly exceeding January, 1989 market prices of the principal commodities. Principal-commodity dependence, transportation routes, cobalt toxicity, and other issues that could affect the availability of cobalt are addressed herein.

Jan 1, 1991

By Howard S. Avery

The wear resistance of an alloy in heavy mill liner sections may be quite different from that of the same alloy in small balls and other light sections. This fact was established by means of a well standardized laboratory test that was validated for ball mill service. The salient properties of mill liner alloys, including austenitic manganese steels, medium alloy hardenable steels, and abrasion resistance cast irons are described, critically compared, and quantitatively ranked in terms of mill liner service. Where they are tough enough the high-chromium and other martensitic cast irons (e.g. Ni-Hard) promise maximum economy, but their section sensitivity is a limitation. To overcome this an extensive research program studied over a hundred experimental alloys, ranking them for heavy section abrasion resistance by means of the laboratory test. Computer analysis of the results provided a parabolic formula in terms of composition, the apexes of the parabolas providing optimum wear resistance. From the extensive family of parabolas one apex was selected for intensive study in experimental liners, pilot plant production, development of quality controls, and finally full scale production. This is a 19% chromium iron critically alloyed with nickel and molybdenum and hardened by heat treatment. It has excellent resistance to various types of abrasion, but its chief advantage is in heavy mill liner sections, where it has about 25% better abrasion resistance than the best of the quality controlled chilled Ni-Hards. It is also tougher. After production problems were solved, a number of ball and rod mill tests were arranged on a guaranteed performance basis. Two of these, representing about 138,000 pounds of mill liner castings, have recently confirmed in service the superiority that was predicted by the laboratory tests.

Jan 1, 1969

By Jelke Dijkstra

This paper presents the results of model pile load tests in a photoelastic material. The soil in this test is represented by an assembly of photoelastically sensitive glass particles, which allows for optical measurements of stresses. In the same test setup, displacements around the pile are measured using digital image correlation (DIC). During the pile installation stresses and strains are recorded. Tests were performed in loose and medium dense particle assemblies. The development of stresses and strains around the pile tip and pile shaft are quantified and presented in this paper. For the loose conditions the results show a small influence on the stress state. For the medium dense conditions a clear stress change is observed.

Jan 1, 2006

By A. G. Yapo, T. W. Camm

"All-in sustaining cost is a metric used by mining companies to reflect the cost of gold mining in a consistent format useful to both investors and mining professionals. Cost reporting focused on the direct cost of mining and processing ore was summarized in the non-GAAP cash cost developed by the Gold Institute in 1996. In 2013, a group of mining companies, working with the World Gold Council, developed a more inclusive approach to reporting costs designed to solve the dilemma of showing a more comprehensive reflection of recurring costs involved in producing gold, without discouraging investors. INTRODUCTION Mining today plays a key role in the development of our civilization as a source of essential raw material and provider of essential fuels, producer of jobs, and a factor in support of the international balance of monetary payment (Camm, 2014). Professionals in mining locate, develop, design and manage ore deposits in an environmentally safe and profitable manner. As mineral deposits become increasingly scarce, new challenges face the industry. A current trend is to an increased emphasis on underground mining techniques for deeper deposits. Operations are safer today than before as companies understand better their work environment and the importance of mining responsibly. A continual challenge for the industry is accurately reflecting the costs and selling price of ore. An enduring characteristic of mining is the situation where the market typically determines the price of a commodity; the main control a company has on the bottom line is to control the cost of production. An attempt to bring light and clarity on the cost of their business will give a better idea to investors on the true profitability of the mining business. Gold producers face this struggle to accurately reflect the cost of production while also seeking to attract the interest of the investment community (Hill, 2013). In order to have a consistent format to report on their production costs, leading gold producers through their alliance inside the World Gold Council (WGC), worked on the adoption of a new cost framework: the All-in Sustaining Cost (AISC) and All-in Cost (AIC). Since 1996, the traditional cash cost reporting has focused only on the mining and processing costs incurred in mining an ounce of gold, which included the costs of goods sold (labor, energy, and consumables costs) and royalties (Table 1). But cash cost reporting ignores many important aspects, like sustaining capital, general and administrative expenses, and site rehabilitation at the end of the mine life (Whelan, 2013). The cash cost was used to attract many investors into the business. In fact the high gross margin (sales minus cash costs) has been promoted the past decades by the industry instead of the net or operating margin. As a result, even when the gold price was high, nearly $1900 per ounce in August 2011, gold producers were not reporting excessive profits in their cash flow / income statements, to the disappointment and incomprehension of investors (Milstead, 2014). The truth was simply that the other costs omitted in the traditional cash cost were reducing the apparent profits."

Jan 1, 2017

By C. Vipulanandan

Installation procedure and the quality of the material used in the construction have significant effects on the behavior of the Auger Cast in Place (ACIP) piles. In this study, Installation and curing of a 760 mm (30 in.) diameter and 12 m (39 ft) long ACIP pile with a design capacity of 1140 kN (128 tons) in hard clay was investigated. Construction quality was monitored using the automated monitoring system where the volume of grout pumped and the pressures were monitored with depth. The curing of the pile was monitored using axial vibrating wire strain gages at four levels and lateral vibrating wire strain gages at two levels. The residual strain and temperature profile in the curing pile was monitored over a period of week to determine the appropriate time for load testing the pile. Axial behavior of Auger Cast in Place (ACIP) Piles in hard clay was studied using full scale load test on an instrumented pile. The load-settlement and load transfer relationships of the pile was investigated based on the load test results. Development of skin friction in the load test pile and the reaction pile was also investigated.

By R. H. Fernald

In 1900, as far as available records show, there were only two producer-gas power installations in the United States. In June, 1915, the number probably exceeded 1,000. Of this number, some 84.5 per cent comprised small plants using anthracite, and only about 15 per cent of the total number utilized bituminous coal and lignite. In addition to these, two plants used wood, and three or four used oil. In the main, however, the larger sized units are operating on bituminous coal and lignite.

Jan 1, 1916

By J Channell, G Phillips

"The Chesney deposit, located 4 km south-east of Cobar consists of three copper-gold rich shoots that lie within a larger, copper dominant lode. A fourth gold rich shoot is located adjacent to the main deposit. The deposit exhibits a strong structural control on mineralisation, as brittle deformation during subvertical extension provided the requisite structural traps to precipitate sulfides from solution. It is postulated that the Great Chesney Fault acted as a fluid conduit, conveying fluids to the site of orebody formation. The continual supply of fluids resulted in cyclic brittle deformation when the fluid pressure exceeded the lithostatic pressure and the tensile strength of the Great Cobar Slate.Evidence supports the hypothesis that ore deposit formation was controlled by: a supply of mineralised fluids transported along the Great Chesney Faulta suitable location for the mineralised fluids to accumulate, accommodated by vertical extension and dilation in certain locationsthe creation of suitable structural traps to capture the sulfides. These traps formed as a result of fault-valve behaviour. Understanding the controls on mineralisation enables prediction of the location of other deposits with similar emplacement history, or extensions of current deposits.CITATION:Channell, J and Phillips, G, 2014. Understanding mineralisation controls – a case study of the Chesney deposit, in Proceedings Ninth International Mining Geology Conference 2014 , pp 301–312 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014

By Yuhua Wang, Haitao Zheng, Guangli Zhu, Yuehao Zhao, Fushun Yu, Dongfang Lu

"Spodumene, feldspar and quartz possess similar surface properties, which make the difficult to separate spodumene from other silicate minerals by flotation. The differences of crystal structure, surface property and floatability of three minerals were studied by various technical means. The results show that Li-O and Al-O bonds in spodumene structure are not strong and easy to be broken. However, Al-O and Si-O bonds in feldspar and Si-O bond in quartz are very strong and not easy to be broken. High contents of Al and Li on spodumene surface were found by XPS measurements, which is benefit for the adsorption of anionic collector. The surface energies of main cleavage planes of spodumene (110), feldspar (001) and quartz (001) are 1.88 J/m2, 2.97J/m2 and 2.68J/m2, respectively. Hence, the exposed surfaces of feldspar and quartz are not saturated and easy to adsorb OH- ions from solution and cause the lower IEP than spodumene. The contact angles of three minerals in water are lower than 16º, suggesting that the hydrophilicity of three minerals is high, and the order of hydrophilicity is quartz > feldspar >spodumene. Correspondingly, contact angles and flotation recoveries of spodumene are bigger than that of feldspar and quartz in presence of a combined anionic and cationic collector named YOA.INTRODUCTION Flotation technology plays most important role for the recovery of spodumene from pegmatite ore. Generally, spodumene with fresh surface is easy to be floated using soap and oleic acid as collector, and the best flotation pH range is 4.0 to 9.0. However, the flotability of spodumene will become worse when its surface was polluted by slime which produced by the weathering of spodumene and other silicates (Dresler et al. 1998; Moon and Fuerstenau 2003; Menéndez et al. 2004; Yu et al. 2015). In addition, the species of Ca2+, Fe3+, Mg2+ and other metal ions in pulp can not only activate the flotation of spodumene, but also the activation of gangue minerals, and then the flotation selectivity of spodumene from gangue minerals became wores (Wang and Yu 2007; Yu et al. 2014). In order to eliminate the negative effects of slime and metal ions on the flotation of spoddumene, the desliming and long time scrubbing with the addition of NaOH and Na2CO3 were adopted. Usually, NaOH shows the activation for spodumene flotation, and the recovery of spodumene increases with the increase of NaOH dosage. Na2CO3 can eliminate the non selective activation of Ca2+, Fe3+, Mg2+ ions in the pulp, and the concentrate grade of spodumene increases with the increase of Na2CO3 dosage. Anionic collectors such as chelants, hydroxamic acid, oxidized paraffin soap, naphthenic acid and oleic acid were widely used for the flotation of spodumene (Dresler et al. 1998; Moon and Fuerstenau 2003; Menéndez et al. 2004; Yu et al. 2015)."

Jan 1, 2018

By A. T. Iannacchione

The Bureau of Mines established geologic factors affecting the mining of the Lower Kittanning coalbed to aid in coalbed minability studies and examined the occurrence of "wants" (places where coal is missing) and types of unstable roof rock strata. Trends established from mapping, including prediction of areas of high methane emissions, were extrapolated to unmined areas. 'Wants' in the coalbed are of two types: Erosional and depositional. Erosional features occur where north-south-trending sand-filled channels cut into the coalbed. Variations in depositional environments have caused the coalbed to "split" into several thinner units. Slickensides, commonly indicative of unstable roof, are adjacent to and on the underside of sandstone channels; they were caused by differential compaction and by soft sediment sliding along the contact between the sandstone and adjacent shale. The frequency of unstable roof also increases where the interval between the Middle and Lower Kittanning coalbed is less than 30 feet. The zones of weakness at the contacts above and below the Middle Kittanning coalbed are the controlling factors for unstable roof in these strata. Methane emissions from the coalbed are controlled primarily by depth, fracture permeability, and rank of coal. Local geologic factors are coalbed thickness, associated rock strata, structure, and proximity to outcrop.

Jan 1, 1979

By D. H. Rubisov, V. G. Papangelakis

Sulphuric acid pressure leaching is the process of choice to recover nickel and cobalt from laterites with variable iron and magnesium contents. The latter influences the acidity levels required for effective leaching of nickel and cobalt, and during leaching, iron is rejected in-situ as hematite. Classical solid/liquid separation is performed via a CCD circuit, the performance of which depends upon the size and shape of precipitated particles. In this paper, precipitates obtained by acid-leaching of various lateritic feeds at 270°C are characterized using SEM/EDX and laser particle size analysis. It is shown that as acidity increases, the shape of the precipitates gradually changes from platelets to spheres, thus improving the S/L separation properties of the residue. The use of hydrogen ion concentration “at temperature,” calculated from a speciation analysis, allows the explanation of this change of morphology independently of the type of the ore feed. The possibility of precipitating magnesium sulphate “at temperature” is also discussed. In order to take advantage of this precipitation for scale reduction (as has been proposed in the past) without compromising the residue quality, [H+] “at temperature” must be controlled within an optimum range.

Jan 1, 2000

By Thomas V. Falkie

In bygone days, the mineral engineer spent most of his/her time on the technical aspects of designing, building, and managing mineral operations. In the last few decades, mostly since the 1960s, increasing amounts of engineering man power and time are spent dealing with federal, state, and local government agencies, laws, and regulations. It is not possible to plan, design, build, or operate mines, mills, smelters, or even office buildings without detailed consideration of government regulations and permitting requirements dealing with environment, worker health and safety, etc. The four chapters of this section provide an overview of the social, legal, political, environmental, and health and safety aspects of mineral enterprise. The section sets the stage for the working engineer/geologist in industry, government, consulting, or academe and points the direction for more detailed study in each of these areas.

Jan 1, 2008

By Thomas P. Mucho

Cable bolts are emerging as the newest ?twist? for roof support in U.S. underground coal mines. For decades cable bolts installed in underground metal mines in the United States and Canada used cement-based grouts for anchoring. The cement anchoring process, because of the time and expense for installation, made cable bolts impractical for use in coal mines. Today, the introduction of resin-anchored cable bolts provides a system more consistent with tradi­tional U.S. coal mine roof bolting practices and requirements. Expecta­tions are that the utilization of cable bolts for a number of U.S. mining applications will expand, particularly in coal mining.

Jan 1, 1998

By Jennifer L. Bell, PATRICK L. YORIO, Emily J. Haas, Susan M. Moore, Lee A. Greenawald

Although researchers have struggled to replicate Heinrich’s safety triangle findings (Heinrich 1931) for various reasons (e.g., no access to his original database and it is unclear if the database was of a single establishment/operation or for an entire industry), the occupational safety community has continued to adopt and expand the applications of this theory (e.g., McSween 2003). Within the mining industry, the potential exists for operations and companies to use concepts from the safety triangle as a way to inform or challenge the practices employed within their health and safety management systems (HSMS) to prevent incidents (Backlund 2016). This paper considers data obtained from the Mine Safety and Health Administration’s databases and demonstrates the validity of applying the safety triangle theory at the mine level. The results support the use of this theory and demonstrate that lower severity incidents can predict fatalities in a subsequent year where significant nuances and caveats to applying the theory are identified and discussed.

Jul 25, 2020

By G. Roberts, S. S. Klima, W. R. Reed, J. Deluzio, G. Ross, A. Mazzella

The abstract discusses the problem of silicosis among roof bolter operators in coal mines due to respirable quartz dust (RCS) exposure. It presents a study comparing a new wet box collection system to the traditional dry box system. The wet box system uses water to saturate collected material, reducing RCS exposure during cleaning. The study found that the wet box system significantly reduced RCS exposures and quartz content in samples compared to the dry box system.

May 11, 2022