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By H. L. Lovall

Huge banks of preparation plant refuse and other non¬saleable materials have accumulated over the years in all major United States coal producing areas. These banks, esthetically and commercially undesirable, can cause air and water pollution and land reclamation and mineral conservation problems for the industry and nearby communities Although some refuse banks have been reworked to recover saleable coal, all remain and accumulation continues. Even those previously processed continue as potential hazards. Among the several problems created by refuse banks, in situ combustion is most treacherous. Of the millions of tons of major accumulations, there are at least 450 refuse banks on, fire at this time Attempts to extinguish such fires are costly, impractical and generally unfruitful. Studies are in progress to evaluate the potential of processing such materials to eliminate the combustion capability and to yield usable fuel and nonfuel products. Aspects of the study now in. development for coal refuse include: (a) evaluation of characteristics (size, sink-float, ash, sulfur and calorific value) of the coal refuse materials which are known to be highly variable, (b) development of an ignition test having significance for in situ conditions, (c) study of processing capabilities (comminution for liberation, pilot plant washing tests), and (d) investigation of potentially significant properties of fuel and nonfuel products which could be altered to enhance their market potential.. Among the latter products are lightweight aggregate, fill for mine slushing operations, construction, etc: Plans are to extend the studies to include the design, erection, and test processing of refuse with a transportable plant,; which could provide basic economic and product utilization data from several locations

Jan 1, 1964

By R. Wang

"Under high stress conditions, rock bursts, borehole breakouts, and spalling events are common phenomena that occur around underground openings. In general, together these three phenomena represent brittle failures of an intact rock mass; however, individually they reflect different failure modes under high stresses. After analyzing and comparing the stress-to-strength criteria for rock bursts, borehole breakouts, and spalling events, proposed by previous researchers, it is found that these brittle failure phenomena share common stress-to-strength prerequisite. The stress-to-strength preconditions for brittle failures can be defined by the ratio of the maximum tangential stress around an underground opening to the uniaxial compressive strength (UCS) (s?max/sci) or by the ratio of the maximum far-field principal stress to the UCS (s1/sci). Both these indicators can be used to reflect the same stress preconditions. For s?max/sci, a ratio of 0.4±0.1 represents the critical stress requirement for brittle fracture. However, for s1/sci, a ratio of 0.15±0.05 should be considered as the critical stress requirement. Numerous engineering case studies and analysis of rock mechanics based on the Hoek-Brown criterion also verify these two stress-to-strength preconditions. Here, these two indicators are presented with an error range because complex rock mass quality ratings, lithology, and geotechnical conditions have profound impacts on the stress-to-strength preconditions for brittle failures. INTRODUCTIONHigh stresses are one of the most important factors that must be considered when undertaking underground rock mass projects (Kaiser et al., 1998). Wang et al. (2009) reviewed current progress in the evaluation of high stresses and their corresponding criteria. However, after clarifying the definition of high stress, civil engineers need to understand the deformation and failure behaviors of rock mass around an opening under high stresses. Under high stress conditions, the deformation of rock masses around an opening can be categorized into two groups, i.e., severe brittle failures (or rock bursts) and compressional plastic deformation of the surrounding rock mass, as indicated in Figure 1."

Jan 1, 2015

By Irving Hartmann

Several recent ignitions of firedamp - a mixture of methane and air - in American coal mines have been attributed to frictional heating when hard rocks were struck while cutting and drilling coal seams. Although none of these ignitions caused severe explosions, they call attention to a problem that can become increasingly significant as mechanized mining is developed further. The power in and rapid release of energy from high-speed machinery has increased the rates of advance into virgin coal creating many problems. Unforeseen faults and hard mineral inclusions may be encountered; coal brought down in this way is finer in size; more gas is released from the seam; it is frequently more difficult to provide adequate ventilation at the' face; and new roof-support problems must be solved. In particular, continuous mining machines (also known as continuous miners) greatly increase the frequency of contact between cutter bits and minerals. In view of these conditions, it may be expected that more gas ignitions will occur as a result of frictional heating unless the situation is understood and remedial measures are introduced. The problem of frictional heating is not new in coal mining. In Europe, particularly in England, it has been a concern for more than a century. During the last 15 to 20 years frictional ignitions have been a major cuase of explosions in British mines. Explanations for the greater number of such ignitions in England may be the special character of the coal measure strata, the mining methods, the rate of gas emission and possibly its composition, and less effective ventilation near the face. To reduce the ignition hazard, considerable laboratory and field research has been conducted, particularly by the Safety in Mines Research Establishment, Ministry of Fuel and Power of Great Britain. Much of the information presented in this report has been drawn from these studies.

Jan 1, 1955

Sampling errors result from heterogeneities within the lot under study. Within a rock mass in situ heterogeneity results in the geological nugget effect, which accounts for most of the natural variability. In broken rock, constitution and distribution heterogeneities are important. A major result of the constitution heterogeneity is the Fundamental Sampling Error (FSE) which is the smallest residual error that can be achieved. It cannot be eliminated, but can be minimised and refl ects the fact that the broken rock sampling process is never completely free of error. Together with other sampling errors, FSE contributes to the total nugget effect. The FSE for a sampling protocol can be evaluated using the so-called Gy equation. Its practical applications to low-grade gold ores have often been unsuccessful due to problems linking the FSE and minimum sampling mass and the defi nition of key parameters such as the liberation diameter. Well-designed sample protocols minimise the total sampling error and hence the nugget effect. Reduction of the nugget effect is a key requirement for all sampling programs whether related to exploration and resource evaluation, metallurgical test sampling, grade control or metallurgical plant sampling. This contribution reviews the relationship between heterogeneity, FSE and nugget effect in gold deposits; and emphasises the need for FSE management throughout the mine value chain.

Aug 1, 2010

By W. Gibson Jaworek

Of increasing importance to the student of fuels economics has been the extent to which different primary energy sources can substitute for each other in the various energy markets of the nation. Knowledge of the nature and extent of fuel interchangeability can aid the fuels economist in projecting trends of energy utilization, as well as giving him a better understanding of the past and present conditions of fuel markets. It is also important to the consumer to know just how much flexibility he can maintain in his energy consuming operations. And, finally, various governmental bodies show keen interest in the degree of energy substitutability in determining public policies concerning the fuels industries. The presence of excess fuel production capacity in the United States during the early 1960's indicates that fuel interchangeability should become more prevalent in the increasingly competitive energy markets of the nation. Discussion of fuel intercompetition is almost always restricted to qualitative terms-because of the lack of comparable statistical data, between the different energy sources in geographic or "type-of-use" fuel, markets. There are exceptions, of course, such as, the excellent fuel consumption data which are available on steam electric generating plants throughout the nation. In other sectors, statistics are at best incomplete.' Inmost instances, indirect fuel consumption indicators, such as sales of fuel burning equipment, are extensively used to measure market shares of a particular fuel; however, these indicators are hard to evaluate precisely without prior knowledge of the total competitive market.

Jan 1, 1961

By Edwin M. Chance

EDWIN M. CHANCE, Wilkes-Barre, Pa. (communication to the Secretary*).-I have read with great interest Mr.. Liebermann's paper reporting dynamometer tests of mine cars and wish to express my appreciation of this investigation. The coal-mining industry needs just such precise study of the problems with which it is confronted.

Jan 10, 1916

By C. Dorfling, M. Tadie, M. Tucker

Electrowinning is the final step in the hydrometallurgical production of high purity copper, involving the passage of electric current through an electrolyte and consequent plating of solid copper to form cathode sheets. Key electrowinning performance indicators are the current efficiency, specific energy consumption, yield, and quality of the metal. The high energy demand and associated cost mean that determination of performance indicators is critical during operation, but ‘online’ measurement is impractical due to the nature of the measurements and corrosive environment brought about by acid mist. This research considered the development of a predictive electrowinning model as a shift towards a pre-emptive approach to attaining plant performance data. A steady-state model was created from input variables available in the industry, using a first-principles approach combining mass balances, electrochemical and thermodynamic equations, and property correlations. A circuit diagram equivalent of an electrowinning cell, containing multiple pairs of electrodes, was used as the backbone of the model. The kinetics of each electrochemical reaction were modelled including iron as a major impurity. Losses in current efficiency due to ineffective electrode contact, short circuits, and stray currents were also incorporated. The model was used to predict the current efficiencies for tests performed at varying conditions in a bench-scale electrowinning cell; the average absolute error between the measured and predicted current efficiencies was 3.2%. The model requires a unique parameter fitting approach for each industrial operation; if parameters are customised for specific plants, the model will be a useful tool to predict performance and can aid the development of effective process control systems in copper electrowinning tank houses. Keywords: Copper; current efficiency; electrowinning; modelling; plating rate

Jan 1, 2020

By D. J. McAdam

As shown in three recent papers by the author, in two papers by McAdam and Mebs, and in a paper by McAdam, Mebs, and Geil," the technical cohesive strength of a metal, in any particular state as regards mechanical treatment and heat-treatment, cannot be represented by a single stress value, but must be represented by a diagram with the principal stressest as coordinates. Each point on the boundary of such a diagram represents a technical cohesion limit. The technical cohesive strength thus comprises an infinite number of technical cohesion limits, each representing fracture under a specific stress combination. Moreover, neither the yield strength1 nor the ultimate strength can be represented completely by a single stress value, but must be represented by a diagram with the principal stresses as coordinates. All combinations of the principal stresses may be classified in three groups as illustrated by Fig. I. Fig. Ia shows three typical stress combinations with no two principal stresses equal. The magnitude of each principal stress is indicated qualitatively by the length of the arrow. Arrows pointing away from the cube indicate tensile stresses; arrows pointing toward the cube indicate compressive stresses. Typical stress combinations with two principal stresses equal are illustrated in Figs. rb and Ic. Such stress combinations would be produced by subjecting a cylinder to combinations of uniform axial and radial stresses. The uniform radial stress may be resolved into two equal principal stresses. with the mutually perpendicular directions rotatable around the axis of the cylinder. Fig. ib shows stress combinations with Sz equal to The greatest principal stress is in the axial direction, and the stress combination tends to cause either absolute or relative increase in length.* Fig. u shows stress combinations with S2 equal to St. The greatest principal stress is in the radial direction, and the combination tends to cause either absolute or relative decrease in length. The complete representation of either technical cohesive strength, yield strength, or ultimate strength generally requires a three-dimensional diagram. When two of the principal stresses are kept equal, however, the strength of a metal may be represented by a two-dimensional diagram with the coordinates representing the axial and radial stresses.6-II In this paper, attention will be confined almost entirely to stress combinations with two of the prin-

Jan 1, 1945

By Steven J. Page

Since 1982 standard calibration materials recommended for respirable crystalline silica analysis by the Mine Safety and Health Administration (MSHA) P7 Infrared Method and the National Institute for Occupational Safety and Health (NIOSH) X-ray Diffraction (XRD) Analytical Method 7500 have undergone minor changes in size distribution. However, a critical assumption has been made that the crystalline silica in ambient mine atmosphere respirable dust samples has also remained essentially unchanged in particle size distribution. The objective of this work, therefore, is to compare recent particle size distributions of underground coal mine dust and the silica component of these dusts with estimated aerodynamic particle size distributions of calibration standard materials MIN-U-SIL 5, Berkeley 5, and SRM 1878 used by two crystalline silica analysis techniques. This work provides resolution to a previously reported discrepancy involving the proper sample dilution for the particle sizing method used. Dust impactor sampling data for various locations in 13 underground coal mines were collected between 1991 and 1998 and analyzed for the respirable mass median aerodynamic diameters. The data suggest that the MSHA P7 Method will underestimate the silica content of the sample by at most 8.5 % in the median size range of 0.9–3.6 µm and that it is unlikely one would obtain any significant error in the MSHA P7 Method analysis when the method uses Berkeley 5, MIN-U-SIL 5, or SRM 1878 as a calibration standard material. The results suggest that the NIOSH Analytical Method 7500 would be more appropriate for a dust sample that is representative of the total (no cyclone classifier) rather than the respirable airborne dust, particularly since the mass fraction in the size range below 4 µm is usually a small percentage of the total airborne dust mass. However, the NIOSH Analytical Method 7500 is likely to underestimate the silica content of an airborne respirable dust sample by only 5–10 %. The results of this study also suggest that any changes that may have occurred in the median respirable size of airborne coal mine dust are not significant enough to cause any appreciable error in the current methods used for respirable crystalline silica analysis.

Aug 3, 2005

By Luis Mercado

El presente texto analiza el panorama global nacional del carbón en el Perú, así también señala las posibilidades de este como alternativa energética frente al petróleo, debido al alza de precios de producción y venta. Para ello, se revisa las reservas de carbón, el contexto geográfico y geológico de las mismas y los métodos de explotación de los países industrialmente desarrollados.

May 1, 1986

By W. G. Hubler

It has been within only the last two or three years that enough progress has been made in preferential flotation to warrant metallurgists in recommending the installation of commercial-sized plants for the treatment of copper-zinc-iron ores. Until the new processes had been worked out successfully, the treatment of this type of ore had proved a stumbling block in the path of metallurgical progress. Separation of lead-zinc ore is comparatively simple. A lead-zinc ore low in iron may be separated and concentrated by gravity con-centration, provided it is not necessary to grind too fine. Owing to the specific gravity of chalcopyrite and sphalerite being so nearly the same, however, their separation by gravity concentration is out of the question. Complex lead-zinc-iron ores in which the several minerals are intimately associated, requiring fine grinding to free them, have been successfully treated by flotation for the past fifteen years. Galena is easily floated, and its flotation, unlike that of chal¬copyrite, is not affected by the reagents used to inhibit the flotation of sphalerite and iron sulphides. When an attempt was made to use the methods of lead-zinc se-paration on copper-zinc ores, it was found that the depressant re-agents added to inhibit the flotation of the iron and zinc minerals would, under certain conditions, depress a large part of the copper. It was also recognized that, in the grinding of copper-zinc ore, soluble salts were generated which were detrimental to flotation unless properly controlled. The main part of this paper will be a discussion of solutions in the grinding circuit in relation to the pro¬duction of soluble salts and their effect on flotation.

Jan 1, 1931

By B. Erik Ydstie, Tor Lindstad, Vianey Garcia-Osorio

"As a result of the high temperatures present in a Carbothermic Aluminum Process the content of aluminum and aluminum sub-oxide in the gases leaving this process is high. These gases as well as energy must be recovered. In a Vapor Recovery Unit were the aluminum compounds react in a series of Heterogeneous Non-catalytic Reactions forming solid, liquid and gas products. The different product phases depend on the temperature present in the system. In this work we present dynamic model of the Vapor Recovery Unit of a conceptual Carbothermic Aluminum Process. Because of the complexity of the system several models are developed and coupled to capture the essential physics of the multiphase reaction problem. A Shrinking Core Model describes the reaction mechanisms. Then material and energy balances are coupled with the thermodynamics properties from the FACT database of thermodynamic properties, resulting in a system of nonlinear Partial Differential Equations. In the paper we describe the model development and governing equations for the reaction mechanisms and fluid flow. Finally we review the numerical schemes created for the solution of the model system. The model can be used for control and design purposes.IntroductionThe Carbothennic Processes for producing Aluminum can be divided into two groups (Motzfeldt et al. (1989)) In the first approach pure alumina is produced and reduced to pure aluminum. In the second approach an alloy (e.g. aluminum and silicon) is made and then aluminum is produced from the alloy. The history of both processes has been described by Ginsberg et al. (1965). At least three aluminum producers began largescale testing of this process in the 60's Alcan, Pechey-Ugine and Reynolds. Alcoa did some smaller scale experiments.Alcoa was one of the first companies to produce aluminum by Carbothennic Reduction (Foster et al. (1956)) and US Patent 2,829,961 April 8, 1958. In this process a carbon containing molten aluminum phase was a floated on top of an oxy-carbide melt. During the cooling the dissolved carbon deposited as aluminum carbide. The carbide was then separated from the molten aluminum by a fluxing agent. This process was successful but economic unfeasible."

Jan 1, 2001

By J-T Zhu, Q-Y Tu, S-L Kong, L Wang, Y-P Cheng, H-Y Liu, Q-L Yang

China is the largest coal-producing country in the world, while the geological conditions of deep coal mining are extremely complicated with high ground stress, high gas pressure and low permeability, which results in the difficulty of gas drainage and aggravation of gas explosion and coal and gas outburst disasters. Co-extraction of coal and gas is an effective method to eliminate coalmine gas disasters and realise the safe exploitation of coal and efficient gas drainage at the same time. This concept is widely accepted by the main coal-producing countries around the world, while the concrete definition of co-extraction is vague and not unified, and there is little accurate theoretical support for co-extraction of coal and gas, which makes it hard to determine efficient gas drainage methods correspondingly according to the features of coal seams in a comprehensive and systematic way. Based on theoretical analysis, laboratory test and field observations, basic thoughts and specific definition of co-extraction of coal and gas were put forward after analysing the occurrence characteristics of coal seams in China. We obtained the mechanism of mining-enhanced permeability and established the corresponding theoretical model, which is the process of fracture network formation through opening recovery of the original fractures and new fractures produced by unloading damage. Based on the core idea of ‘mining-enhanced permeability’, engineering approaches of ‘unloading by boreholes drilling’ for the single coal seam and ‘unloading by protective seam mining’ for the coal seam group were proposed to realise safe and efficient co-extraction of coal and gas. Meanwhile, combined with engineering practice, we put forward the construction principle of coal exploitation and gas drainage system in different coal seam occurrence conditions. The above methods were applied successfully in the Tunlan coalmine in Shanxi Province and the Panyi coalmine in Anhui Province, which had established the ‘underground-surface united’ spatial gas drainage modes, and could ensure safe and efficient co-extraction of coal and gas in the outburst coalmines.CITATION:Cheng, Y-P, Wang, L, Liu, H-Y, Kong, S-L, Yang, Q-L, Zhu, J-T and Tu, Q-Y, 2015. Theory of safe and efficient co-extraction of coal and gas and its applications, in Proceedings The Australian Mine Ventilation Conference, pp 79–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

INTRODUCTION This paper was originally presented at the Platinum Adding Value Conference, held at Sun City from the 4th to 6th October 2004. Narrow reef mining may not be applicable to the base metal operations in Zambia, however, it is considered that the methodology used is equally appropriate to the development of technology and mining methods in mining environments other than narrow reef mining. The purpose of this paper is to explore the integration of technology and stoping systems. For the last hundred years the South African narrow reef mining industry has battled to control working costs in a labour intensive industry. It is only through the application of appropriate technology that change will occur. Stoping systems, because it is the stoping method and methodology that is at the heart of the mining system. Introduce a different technology that results in a more efficient stoping system and the mining system will look after itself. The technology applied to stoping in narrow reef mining, over the last 100 years, can be categorised as follows: ? The introduction of pneumatic rockdrills early this century. The cumbersome rig mounted units being replaced by smaller, lighter, hand held units that were then made easier to use with the addition of an air leg. (The so called Swedish method of mining.) As late as the early 1970s some drilling was still being carried out without the assistance of an air leg. ? Scraper winches to replace gravity and shovels to move rock both in the face and the gullies were first introduced in the late 1920s. ? Hydraulic props installed close to the face and capable of applying force against the hangingwall as well as yielding in a controlled manner under dynamic load arrived in the 1960s. In many instances these have now been replaced by yielding elongates fitted with water hydraulic tensioning devices. ? Some people argue that the introduction of tungsten carbide inserts, to improve drilling, was equally important.

Jan 1, 2005

By Reza Kamali, Mohsen Bashiri, Hadi Fanisalek

"Half of the input energy to aluminum reduction cell will be lost as waste heat which could be studied for possible recovery. Since price of energy is increasing and the main production cost in primary aluminum industry is energy, so waste heat recovery consideration will be interesting. One of the possible choices for recovering is from aluminum exhaust gases that needs minimum modifications for reduction cell and has no influence on cell heat balance which is vital for the operation. By using heat exchangers with in-line and staggered tube arrangements which placed before fume treatment plant (FTP) we will be able to recover enough amount of heat. The main challenging problem which is necessary to overcome will be the heat exchanger material and its design because of corrosive and dusty exhaust gases from potroom. In this paper, a desalination system with six effects of evaporator is proposed for producing distilled water by using recovered heat from hot exhaust gases. The calculated amount of produced distilled water is around 27,000 / in this specific suggested desalination plant. The suggested desalination plant is based on Hormozgan Aluminum Company data (Hormozal) in Bandar Abbas, Iran which is constructed by the Persian Gulf.IntroductionWaste heat losses arise both from equipment inefficiencies and from thermodynamic limitations on processes. The exact quantity of industrial waste heat is poorly quantified, but various studies have estimated that as much as 20 to 50% of industrial energy consumption is ultimately discharged as waste heat [1]. In order to achieve a final decision for establishing the waste heat recovery plant in any type of industry, a strong feasibility study is mandatory. Also, we need to remember that the possible amounts of energy and suggested process plant for recovery have to be investigated before starting any feasibility study. This kind of study which is important to be finished before moving to feasibility step is mainly a theoretical study, and was done for the Hormozgan Aluminum Company (Hormozal). In addition to the exhaust gases from the potroom, the exhaust gases from anode baking plant appear to have a better potential for waste heat recovery compared to potroom exhaust gases. The average temperature of exhaust gases from anode baking kiln is 120°C higher than the exhaust gases temperature in the potroom. This needs further investigation in a different study, because this study is just focusing on potroom exhaust gases."

Jan 1, 2011

By Savage E. N

The porphyry copper minerals of Melanesia occur within a host of narrow veinlets in predominantly quartz diorite stocks or as contact metasomatic masses in skarns adjacent to the intrusion. Some 90 per cent of the constituent minerals comprise pyrite or marcasite, chalcopyrite, and magnetite with the remainder mainly bornite and hematite with accessory rutile and chalcocite together with several trace minerals. Gold is found mainly as inclusions in chalcopyrite, and minor molybdenite occurs likewise.Of particular significance is the persistent occurrence of accessory rutile of hydrothermal origin intimately intergrown with chalcopyrite. The rutile occurs relatively late in the hydrothermal sequence and upon weathering of the deposit may be released on a cumulative basis possibly in sufficient amounts to constitute a particulate pathfinder mineral which may aid in prospecting.Rutile is present in all the Melanesian occurrences studied and is also prominent in several American deposits.The porphyry copper mineralogy is characterized by the presence of accessory hydrothermal rutile intergrown with chalcopyrite.

Jan 1, 1975

By T Kojovic

"The index A*b, determined from the Julius Kruttschnitt Mineral Research Centre (JKMRC) drop weight tester (DWT) results, has become well-known in the mining industry as a reliable measure of ore hardness in impact or crushing, having the inferred units of t/kWh. This index evolved from a long history of comminution studies at the JKMRC, including the development of the now superseded JKTech twin-pendulum, the industry standard JK Drop Weight Tester (JKDWT) and the faster alterative JKMRC rotary breakage tester (JKRBT). A reduced version of the DWT, the semi-autogenous grinding mill comminution test (SMC test®), also provides estimates of the A*b though the testing of only one particle size at five specific energies. Experimental determination of A*b using the above devices/tests requires samples, with sufficient mass, to be sent to designated laboratories, registered to conduct such tests. This protocol is fine for bankable and commercial testing, where material characterisation data is used in conjunction with machine specific data in modelling and simulation, and power based calculations. However, for comparative testing, where results are required at the time of sampling (eg for plant troubleshooting or spot-surveys), or for rapid ranking of geometallurgical samples, these existing tests simply do not provide a timely, viable and cost-effective solution. In order to address this critical void in the realm of comparative testing, a new device has been developed, exploiting a central feature of single particle impact testing – that the A*b can be reliably estimated using one precise low energy test. This device, for which a patent is currently pending, called the HIT (Hardness Index Tester), has been precision engineered to allow users to break narrowly sized fragments at a set specific energy, in a safe and easy manner. The manufacturing materials have been chosen carefully to ensure compatibility with the intended use and portability to any site, whilst minimising cost. The device is supplied with a novel quality assurance / quality control (QA/QC) feature, to ensure that the targeted potential energy is consistently delivered. The product from the HIT breakage test can be quickly sized using a single screen to determine the mass per cent undersize, from which the A*b index is calculated directly at site – eliminating the need to send the raw data off-site for analysis. On presized fragments, a single test using 20 fragments takes less than five minutes to complete, and the results are immediately available. The HIT is currently being tested at a major mining laboratory in the US and the results to date have proved it can deliver on all fronts. This paper describes the new prototype device, which offers users a low cost in-house mechanism for estimating the A*b at any mine site, with potential applications on fragments up to 25 mm from drill core, blast chip rejects or the grinding circuit feed. It also outlines the results of field tests carried out by an objective third party mining group and compares the results with those from current industry standard tests conducted on the same material.Citation:Kojovic, T, 2016. HIT - a Portable Field Device for Rapid Testing at Site, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 9–16 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Sherwin F. Kelly

With the progressive exhaustion of ore deposits easily discovered by surface prospecting, the attention of scientists is being turned more and more to the employment of mechanical means for the location of ore bodies whose outcrops are not visible. The dip needle, the Eotvos Torsion balance, and various methods of electrical prospecting are illustrative of the modem tendency. Interest in the possibility of applying electricity to the solution of many of the prospector's problems dates much farther back than is usually realized. The first person to notice an abnormal intensity of electrical activity in the region of certain ore bodies was an Englishman, R. W. Fox, who experimented on the Cornwall copper and tin veins about 1830. Dr. Barus, in the United States, carried the early experiments a step further in his work on the deposits of Eureka, Nevada, about 1880. He made the very definite suggestion that the phenomena noticed would be of material aid to the prospector. Not until Professor Schlumberger, of the Ecole des Mines, Paris, took up the matter, shortly before the war, was any definite effort made to put electrical prospecting on a commercial basis. His work resulted in the establishment of sound principles and practicable field technique, for two distinct methods of prospecting.

Jan 1, 1924

Refractory copper ores (CROs) in central Africa contain copper minerals that are locked up in a micacious solid matrix or associated with carbonate, sulfide and phosphate minerals. Several researchers have reported that the recovery of copper from CRO material by an acid-leaching process is not economically feasible, due to the presence of excess gangue-acid-consuming minerals such as calcites, dolomite, asbolane and iron oxides. Since the proportion of acid-insoluble copper (CuS) is about 28% of total copper and total free sulfur is extremely small, sulfide flotation was considered unfavorable. Consequently, hundreds of millions of tons of CRO material have been stockpiled specifically at the Nchanga Mine of Zambia. In terms of copper distribution in CRO material, a significant portion of total copper exists as carbonates (39%) and oxides (17%), while 28% of the copper is acidinsoluble (CuS). The rest of the copper is in the form of carbonates (16%) and (hydr) oxides (17%). This means that only about 72% of total copper is recoverable through the non-oxidative acid-leaching process. In this study, batch leach tests were performed on CRO solids (d95 = 95%) to establish the gangue acid consumption values at different feed pH values and to evaluate the leaching characteristics of copper, manganese and iron within the CRO material. Subsequently, continuous leach tests were performed on CRO solids (106 um, 80% passing) using optimum leach conditions derived from batch tests. This paper aims to show that sustainable copper recovery can be achieved by selecting leaching conditions whereby gangue acid consumption (GAC) values become significantly small and the final concentration of manganese and iron in the leach solution are appreciably low.

Nov 1, 2011

By Georgene Renner, Chee Theng, William Gleason

"With more than 900 booth spaces sold and 630 exhibiting companies displaying their wares, there was something for all 7,804 attendees on the exhibit floor of the 2015 SME Annual Conference & Expo in Denver, CO Feb. 15-18. The following is a sample of what was offered at the 2015 meeting.3D Laser MappingData collection and data analysis are changing how mining is done. One field in which technological advancements have made safer and more efficient operations possible is through site and slope monitoring.3D Laser Mapping, a United Kingdom-based company, was on hand at the 2015 SME Annual Conference and Expo to display its solutions for the mining industry, including its SiteMonitor4D system.The state-of-the-art laser measurementbased system was developed in partnership with geotechnical engineers and mining surveyors, and is a simple-to-use, reliable solution that has the flexibility and performance to function in a range of monitoring applications.The system measures and monitors the stability of rock faces, landslips and man-made structures, including ongoing, periodic measurement of volumes - stockpiles, cutbacks and waste dumps and has high-speed laser scanning for regular mapping of large areas by mounting the scanner on a vehicle.With specifications that other monitoring techniques cannot achieve, laser scanning opens up a new dimension in mine measurement and monitoring.www.sitemonitorsystems.comA.R. Wilfley and Sons Inc.Founded in 1919, A.R. Wilfley and Sons Inc. has been manufacturing dynamic-seal and static-seal pumps in Colorado for nearly 100 years, delivering its high-reliability, low-maintenance, heavy-duty process pumps and slurry pumps to the global mining industry. The family-owned company is now in the hands of the fifth generation."We are the dynamic-seal experts," regional sales manager Cesar Murillo said. "Most other companies are unable to do 100 percent dynamic seals and have to use mechanical seals or packing," he said, but Wilfley’s sealing technology does away with the need for mechanical seals and packing and their associated problems. As a result, solids and slurry handling capabilities are high, the pump can be run dry, and product dilution is eliminated. The pump can tolerate more misalignment, more cavitation, and more vibration in the pump during operation."

Jan 1, 2014