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By O. E. Polter, W. J. N. Fernando

Smelter-grade alumina is usually produced by the calcination of gibbsite. The ideal energy requirements for the calcination of gibbsite have been analysed and compared with the actual energy consumption of some industrial calcination processes. The consumption of most of these is considerably in excess of the ideal. Methods suggested for calcining dry gibbsite feeds which claim energy savings of 10-14% consume 26-34% more than the ideal energy requirement for dry feeds. This study indicates that it should be possible to recover appreciably more energy, giving further improvements in fuel efficiency, both in existing gibbsite calcination processes and in methods that have been proposed for the stagewise calcination of dry gibbsite

Jun 13, 1905

By Lassi Klemettinen, Ari Jokilaakso, Dmitry Sukhomlinov, Pekka Taskinen

The solubilities and distributions of molybdenum and iridium in iron silicate slag and copper-iron mattes were studied using an equilibration-quenching technique and subsequent direct phase composition analyses by EPMA (Electron Probe X-ray Microanalysis) and LA-ICP-MS (Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry). The equilibrations were carried out on a wide matte grade interval, ranging from 55 wt-% Cu to 75 wt-% Cu, in pSO2 = 0.1 atm at 1300°C. The results in equilibrium with a solid iridium-molybdenum alloy indicated an iridium solubility of 150–500 ppmw in the sulphide matte, depending on the matte grade, and a molybdenum solubility of 100–600 ppmw. Iridium was distributing predominantly in the sulphide matte with the distribution coefficient of 10+3 - +4 but molybdenum deported predominantly in the slag with Lm/s(Mo) = 0.02–0.1. The effects of alumina and lime additions in the smelting slag were also examined. INTRODUCTION Iridium is a highly siderophile element (HSE), which means that it is incompatible with the sulphide forming elements and possesses a small solubility in mattes, such as copper- and nickel-iron sulphide melts. Molybdenum behaves only modestly in that way (Walker & Li, 2008; Righter et al., 2017). They both are known to be trace elements accompanying copper and nickel sulphide ores. No solubility data, however, are available for them in copper-rich sulphide mattes. Geochemical data on the behaviour of Ir and Mo deal mostly with low-iron silicate systems, e.g. basaltic melts, and high-sulphur sulphide solutions and mattes (Ertel et al., 2008; Fonseca et al., 2007). They also indicate that Ir and Mo dissolve in silicate melts primarily as oxides and not as electrically neutral metal species. Most geological data of iridium focus on high-sulphur systems of the monosulphide composition and typically Fe-Ni mattes where copper is a trace element (Fleet et al., 1996; Sattari et al., 2002). Direct solubility measurements for mattes and iron-lean silicates have also been made using pure Ir or an Ir alloy as the saturation phase (Borisov & Palme, 2000; O’Neill & Eggins, 2002; Makovicky & Karup-Møller, 1999; Ertel et al., 2008; Mungall & Brenan, 2014). A recent summary about the solubilities of HSE’s in iron- and sulphur free silicates is available in Laurenz (2012). The thermodynamics of molybdenum partitioning between oxides and Fe-S-O melts was studied by Mengason et al. (2011). Their results indicate strong accumulation in the iron-rich sulphide in reducing conditions (pO2 = 10-9.6 atm in Ni-NiO equilibrium at 1050°C). Molybdenum dissolves in iron-lean silicate melts as MoO3 species in oxygen pressures above the Fe-FeO equilibrium and as MoO2 in more reducing conditions (Farges et al., 2006; Righter et al., 2017).

Jan 1, 2019

By R. Strydom, J. H. Selby

Published information is available on the radiological impacts of disposing of zircon sand in a landfill. Zircon flour by virtue of its finer particle size presents a different set of issues during disposal. This paper describes two options for disposal of such fine grained materials – namely incorporation into concrete aggregates and agglomeration by addition of cement. The study considers the radiological exposure of the public from such disposal methods and concludes that these options are viable alternatives for the safe disposal of waste zircon flour. The disposal of zircon into concrete aggregates at a rate of 10 per cent produces a sufficiently low effect to allow such aggregates to be used in building foundations or other such mass concrete applications. The use of cement agglomeration methods will also provide a safe method of landfill disposal provided at least 20 cm of soil cover is included.

Jan 1, 2003

By Jan Wolski

Increasing interest in the Bucket Wheel Excavator (BWE) technology calls for a universally understandable definition of suitable performance factors which would reflect the unique features of this technology. The importance of properly designed and calculated performance factors for the BWE systems cannot be overemphasised. They are used by all levels of management in any mining organization for a wide variety of purposes, in particular for budgeting, for selecting new equipment, for monitoring current equipment and for comparison with other operations.

Jan 1, 1984

By T. A. Utigard

To improve recoveries of Ni, Cu and Co in the Inco flash furnace, a new operating concept was investigated. By adding sufficient coke to form a supernatant coke layer, a reducing barrier would form allowing for improved reduction of descending oxidized sulfide mineral particles formed in the flame. The objective of this investigation was to study the kinetic mechanism and efficiency of the coke layer to produce a sulfur deficient matte. The mechanism and rate of carbon reduction of each of the phases formed in the flash flame, i.e. sulfides and oxysulfides were investigated by means of X-ray visualization tests. Graphite-slag reduction was also conducted for comparison purposes. In the case of slag, poor wettability and the formation of a gas film on the surface of the carbon reductant are often blamed for limiting the reaction surface area that ultimately results in poor reaction kinetics. The X-ray visualization tests confirmed that matte and oxysulfide wet coke better than slag and that the rates of reduction of matte and oxysulfide are faster than that of slag.

Jan 1, 2005

By B. K. Loveday

The South African Institute of Mining and Metallurgy hosted a School on 'The Practical Design of Comminution Processes' at Megawatt Park (near Johannesburg) on 14th to 16th May, 1991 Derek Barratt, a Senior Consultant of Wright Engineers, Canada, and the main speaker, provided a good insight into how Wright Engineers design milling circuits, particularly large semi-autogenous mills. He was ably assisted by Jens Lichterof Allis Mineral Systems, who described some interesting examples of pilot-plant testwork and summarized South African milling practice. Mike Moys of the Witwatersrand University spoke on the influence of pulp viscosity on mill performance, and Johan Engelbrecht and Jeremy Bosman of Multotech

Jan 1, 1991

By Arthur B. Cummins

It is appropriate to discuss diatomite at an AIME meeting in San Francisco. California has led the nation, and the world, in the production of diatomite products for more than 40 years. It appears that our State will maintain this position for a long time to come. Diatomite today ranks high in the list of California mineral commodities, with a total value since 1889 well in excess of $100 million. California's production has more than doubled since 1942. In 1959, the value of diatomite production in California is exceeded only by the following industrial mineral materials-borates, stone, sand and gravel and cement20,28. Also, not unimportant is the production of diatomite in each of our other Pacific Coast States, including Nevada. First, let us define diatomite. It is a sedimentary siliceous rock of organic origin, which consists mainly of the fossilized remains of diatoms. Diatoms are microscopic aquatic plants which have the capacity of precipitating silica bio-chemically so as to form a part of their organized structure. In the economic sense, we are not concerned with the numerous types of sedimentary materials which contain minor amounts of diatom residues, or with impure or highly indurated siliceous materials, which may have been formed from diatomite2. Diatomite (synonyms--diatomaceous earth, kieselgurO is a term generally restricted to material of such qualities as to be suitable for commercial uses. Diatomaceous silica is a designation which is best used to distinguish the basic component of diatomite, that is, the substance of the silica shell itself, and which is the major' constituent of beneficiated diatomite or processed diatomaceous products.

Jan 1, 1959

By L O. Montpetit

The economics of the asbestos mining industry of Canada, and the physical and chemical characteristics of asbestos fibre, as well as exploration, mining, milling and quality control methods, have been described by several authors in the past few years. The scope of this presentation is to survey the application of asbestos fibres in the major product groups of the construction industry in North America. Principal categories considered include flooring materials, asbestos-cement pipes and building products, high-temperature insulation, textiles, saturated asbestos felts and asphalt com pounds. During 1962, the asbestos mining industry of Canada produced an estimated 1.3 million tons of chrysotile fibre grades, and production capacity is expanding. The market demand for chrysotile fibre, on this continent, has been in the order of 50 per cent of the production volume. The asbestos industry is dependent for growth on the construction industry. Product research is active in finding new uses for asbestos fibre; some of the new developments are presented, including the use of short-fibre asbestos grades for extending the life of asphalt pavement.

Jan 1, 1963

By J. C. Kurnia

Methane is recognized as one of the prime causes of underground mine disasters around the globe. A cost-effective mine ventilation system and methane control is required to ensure a safe and productive environment in an underground mine whilst keeping energy usage and operating cost at minimum. Typically methane enters a mine environment or tunnel from localized distributed sources at high initial concentration. Hence, an understanding of its dispersion from discrete sources is important to design a methane management system via effective ventilation. This study employs computational fluid dynamics to model methane dispersion in an underground tunnel which has a number of discrete sources of methane and effective ways to dilute and or disperse it. Air flow distribution within the tunnel as well as methane dispersion is simulated by solving the governing transport equations subject to appropriate boundary conditions. First, the effectiveness of ventilation duct placement is examined. Several possibilities are explored and investigated. It is found that the common configuration utilized in underground mine performs best as compared to other configurations in maintaining the concentration of methane below permissible levels. Next, a novel intermittent airflow ventilation system is proposed and evaluated via simulation with the goal of reducing the energy cost whilst maintaining methane level in the mining face below the allowable level. Parametric studies are conducted to investigate effects of various factors influencing the effectiveness and performance of this novel intermittent ventilation system. This study will provide some new ideas for designing an efficient and effective underground mine ventilation system by lowering the net average amount of air that needs to be circulated in the tunnel for a safe operation. KEYWORDS

Aug 1, 2013

By R. W. Thompkins

"PREFACEThis paper will be published in three parts. Part 1, in this issue, will cover the occurrence of uranium, radiation from uranium ores, the uranium series, radioactive theory, radioactive equilibrium and application to the radon series, the working level, the theory of emanation and diffusion, transport by thermal diffusion of radon emanating from porous rocks, and definitions.Part 2, to appear in the October issue, will deal with radiation theory applied to uranium ores, other radon migration factors , fact ors affecting the radon gas release rate, measurement of radon gas emanation rates, the tunnel concept, variation of emanation rate with grade, and estimating radioactivity from grade analysis.The series will conclude with Part 3, in the November issue, which will discuss the techniques for controlling radiation and give some example calculations.1.0. Occurrence of Uranium1.0.1. Uranium is widely distributed in nature. Sedimentary rocks contain less than igneous or metamorphic rock s and as the outer 10 miles of the earth's crust is composed of 95 per cent igneous and 5 per cent sedimentary rock, it has been estimated that about 1.3 x 1014 tons of uranium exist in the earth's crust.1.0.2. It is not surprising, therefore, that radiation has existed naturally in the ear h ever since the beginning of time. It is found in such places as:(1) non-uranium mines;(2) houses not close to or connected to uranium mines;(3) ground-water tables supplying drinking water to large populations.1.0.3. All mines do not necessarily have abnormal radiation in them, but it is possible for many mines to have abnormal levels of radiation. Therefore, all underground mining operations should be tested for radiation."

Jan 1, 1982

By A. M. Olivarez

The elucidation of the theory of plate tectonics has provided a conceptual framework for understanding the formation and distribution of different types of ore deposits. For example, we now recognize that certain kinds of mineral deposits are generally associated with a particular type of plate boundary (i.e., massive sulfides often occur along divergent plate boundaries, whereas porphyry copper deposits are typically found along convergent boundaries). During certain geologic time periods, plate reorganization events have changed the relative proportion of different types of plate boundaries. Corresponding changes have been observed in the abundance and distribution of ores deposited during these times. The present study examines the temporal aspects of this relationship; i.e., do plate reorganization events play an active or passive role in ore formation? In other words, do plate reorganizations simply provide a more favorable tectonic setting in which ore formation can occur over significant time periods, or are they directly linked to the mineralization process? We have examined this question by comparing regional tectonic histories with the ages of known massive sulfide and porphyry copper deposits. Because these deposits, in particular massive sulfides, form as a result of hydrothermal activity, we have also compared regional tectonic histories with proxy indicators of this process in the marine sedimentary record. These indicators include increased mass accumulation rates of Ca, Fe, Mn, and opal, characteristic changes in the Sr/Ca and Mg/Ca ratios of biogenous carbonates, and shoaling of the carbonate compenstion

Jan 1, 1988

In some 35 years in the explosive and construction industries, we have probably seen the extremes in drilling and blasting practices. All of you know that it is difficult if not impossible, to separate those two operations, particularly when we are searching for an optimum. Early in my career while doing engineering survey work for a major cross country pipeline construction company, we witnessed some of the wildest blasts imaginable, and they were wild for two reasons. Both the drill hole diameter and the drill pattern were such that when loaded with explosives, the factor in terms of pounds/cu. yd. was extremely high. On the other hand, in 1982 we were in an underground coal mine where just one hole was used to prepare a 20-ft. (6m) wide face. In this coal mine, they brought down 7 yd3 (5.35m3) of coal with just 1 lb. (.454 kg) of explosive. On a pipeline job, the factor may only be .1 yd3 per lb. of explosives. Open pit operations in the same geographical area may have almost the same type of rock, but similarities could end there. The several operators over the years will have installed different size-crushing equipment or variances will exist in other facets such as drilling, excavating, and haulage units. That tells us that if we have 6 operations in that common area, we are faced with a fact that there is an optimum drilling and blasting pattern for each of those six. We start at that point. We will note from Figure No. 2 the simple equations for determining either cu. yds. or tons. For a rock heavier than limestone, it may require only 10 to 11 cu. ft. (.31m3) for 1 ton (.91 metric ton) of rock in place.

Jan 1, 1986

By Bernard L. Merlo

INTRODUCTION Modern mine management is constantly striving to develop improved mining methods which will not only increase productivity, but will also provide a safer work environment and make the most efficient use of our natural resources. Progress can be seen in this area by tracing mining methods through history. Work that was originally done with hand tools progressed with the age of mechanization to conventional mining, matured to continuous and longwall mining, and the advent of short¬wall mining, a combination of continuous and longwall, has recently been seen. This new method of shortwall mining provides a promising method for safe and ex¬pedient coal extraction. This study focuses upon the planning, design de¬velopment, and operation of the first producing short¬wall unit in the US which was operated in the Pittsburgh coal seam in northern West Virginia. MINE DESCRIPTION The mine is located in northern West Virginia at Grant Town in the heart of the high volatile Pittsburgh coal seam. Originally opened in 1901, the mine has be¬come one of the largest in the US, encompassing an area of approximately 103.6 sq km (40 sq miles). The seam being mined was the high volatile Pittsburgh seam which ranged in thickness from 1.8 to 2.96 m (6 to 91/2 ft). Three types of mining methods were employed: con¬tinuous mining, longwalling, and shortwalling, with each type accounting for 50%, 30%, and 20% of total pro¬duction, respectively. A total of 630 contract and super¬visory personnel were employed to produce the mine's designed annual tonnage of 1.8 Mt (2 million st). There were ten producing sections, eight continuous miners, one longwall, and one shortwall, operating a total of 22 unit shifts per day. Eight shafts, varying in depth from 80.2 to 194.2 m (263 to 637 ft) provided entrance to the Pittsburgh coal seam. These shafts were used for ventilation, portaling, coal hoisting, supply, and emergency escape hoisting. Ventilation was achieved by means of three exhaust fans which provided 707.9 m3/s (1.5 million cfm) of air to the mine and removed approximately 141 584 m3 (5 mil¬lion cu ft) of methane per 24 hr period. The room-and-pillar method was used for secondary recovery with designed barrier blocks between panels of 61 m (200 ft) in width. A double row of blocks was left around each gob area to provide efficient bleeder action

Jan 1, 1982

By P. D. Kovscek

The Bureau of Mines equipped a longwall shearer with a water-jet-assisted mechanical cutting system to determine the effect of the high-pressure sprays on machine performance, airborne dust levels generated, and size of particles formed. Testing was conducted on a simu-lated coal block (coalcrete) while cutting at a water pressure of 190 psi and at water-jet-assisted pressures ranging from 1,000 to 6,000 psi. The shearer motor energy used by the shearer while cutting coalcrete was determined for each cutting condition. Results indicate that the motor energy required by the shearer for each ton of material cut did not vary significantly as the water pressure was increased. Results of dust measurements recorded near the cutting drum indicate that at water pressures above 3,000 psi, dust reductions up to 85 pct were achieved com-pared with cutting with conventional sprays. Analysis of the particle size distribution during cutting showed that increasing the water pres-sure resulted in increased median particle size. In light of these results, various mechanisms for water-jet-assisted cutting are discussed.

Jan 1, 1986

By V. C. Pandolfelli, S. F. Santos, L. A. Rodrigues

Under conditions of stable crack propagation at room temperature, the elastic energy stored in ceramic materials is converted mainly to surface energy. However, at high temperatures, creep may also occur in such materials, in which case it will present a ductile behavior. This paper discusses the brittle-ductile transition of a refractory material. Stable crack propagation and creep tests were carried out under a three-point bending device. A commercial ceramic containing 63 wt-% of SiO2 and 31 wt-% of Al2O3 was used as testing material. The results revealed that the change in behavior from brittle to ductile was caused by softening of a vitreous phase present in the material's microstructure.

Jan 1, 2004

By S E. Box, J L. Mauk

The Middle Proterozoic metasedimentary rocks of the Belt Supergroup contain important metallic mineral deposits like the diagenetic sediment-hosted stratiform copper mineralization, including the Troy (Spar Lake) deposit and the epigenetic hydrothermal veins in the lower Belt and Ravalli Group in the Coeur d'Alene district. Magnetite (Fe3O4) is a common and widespread accessory mineral in these rocks and can have multiple origins including ore stage in deposits, mobilization stage in source rocks, metamorphism of red beds and alteration mineral in thin halos enveloping Ag-rich veins in the Coeur dÆAlene district. As shown in several classic studies, the composition of magnetite from igneous rocks varies significantly in response to controlling factors such as melt composition, temperature, silica activity, and oxygen and sulphur fugacity. Therefore, the distinctively different geologic settings within the Belt Supergroup strongly suggest that there may be differences in the magnetite compositions. However, initial microprobe analyses detected no variation in magnetite composition.   Three possibilities may give an adequate explanation for these initial results: 1.      the magnetite formed primarily as pure Fe3O4, 2.      one or more tectonothermal events led to regional scale re-equilibration that affected all rocks in the field area, and 3.      the variations in the composition are below the detection limit of the microprobe.

Jan 1, 2007

By B. R. Mohal, F. F. Aplan, S. Chander

"The wetting behavior of coal has been determined in the presence of nonyl and octyl series of nonionic surfactants containing polyethoxy groups of different sizes. The wetting behavior was determined by a modified Walker technique and contact angle measurements. The results show that the wetting rate of coal varies with coal rank, structure of the hydrocarbon chain and number of ethoxy groups in the hydrophilic group of the surfactant. A close relationship has been observed between the wetting rates and the short-time advancing contact angles.INTRODUCTIONNonionic surfactants are used in many applications to improve wettability of solids. They can be used as dispersing agents [ 1 ] or dust suppressants [ 2-5] and to control the flotation, flocculation, filtration and, flowability of particulates. This study was undertaken to study the effect of a series of nonionic surfactants on the wetting behavior of coal. Two series of surfactants, namely, ethoxylated nonyl and octyl phenols were used. The nonyl phenol series con tains a linear hydrocarbon chain containing nine carbon atoms (CH3 ( CH2 )8-C6H4- ( OC2H4 ) n, where n is the number of ethoxy groups) . The octyl phenol series contains a branched hydrocarbon chain containing eight' carbon atoms ( ( CH3 ) 3CCH2C ( CH3) 2-C6H4- ( OC2H4 ) n ).Initial wetting rates — modified Walker techniqueWalker et al. [ 6 ] developed a sink test to determine the wettability of coal particles. In this technique, coal particles are dropped individually onto the surface of surfactant solutions of different concentrations, and the most dilute concentration in which coal would sink ""instantaneously"" is determine& This technique is a variation of a procedure initially developed by Draves and Clarkson [ 7 ] to determine the effect of surfactants on wettability of cotton fibers."

Jan 1, 1989

By N. W. Lord

Having recently had occasion to make a series of analyses of fire-clays for the present Ohio Geological Survey, I found that the amounts of potash and soda determined indirectly by measuring the chlorides volumetrically did not " check " with those obtained directly. Investigation with the spectroscope showed the presence of lithia in what seemed very appreciable quantities. The examination was made of a considerable number of samples, and in every case this element was found, though in varying amounts, as judged by the intensity of the spectrum. To guard against error from the impurity of reagents, the whole process was repeated, using the same reagents in corresponding amounts, but leaving ont the clay. In no case did these " blanks" show lithia; hence the presence of this element in the clays seemed to be established conclusively. In the same series of analyses, titanic acid, in amounts varying from three-tenths to nearly two per cent., was found. The presence of titanium was first observed in the Ohio clays, nearly three years ago, in the examination of clays from Logan. The occurrence of this element is, of course, not unusual in clay, but I believe that none of the published analyses of Ohio clays give it; certainly none of the former Ohio geological reports speak of its presence. The following analyses show both the above ingredients. They were made during the summer of 1883.

Jan 1, 1884

By Stephen Hoffman

The Environmental Protection Agency (EPA) is investigating approaches to control non-coal mining wastes. In May 1988, the EPA's Office of Solid Waste (OSW) released a document that outlined an approach to manage non-coal mining wastes and materials. This document was called Strawman I. It was a staff-level approach designed to aid the continued participation of interested parties and to enhance EPA's understanding of mining waste issues. EPA has been working with states, public interest groups and the mining industry to gather information and to solicit input on waste management approaches. The involvement of the states in the Strawman process has been coordinated by the Mine Waste Task Force of the Western Governors' Association and the Interstate Mining Compact Commission. Involvement of public interest groups has been coordinated through Colorado Trout Unlimited. And the participation of the mining industry has been managed principally by the American Mining Congress. In May 1990, EPA released Strawman II. It was based on comments submitted to the EPA on Strawman I and on information given to the EPA by interested parties since 1988. Strawman II is again a staff-level approach to protect human health and the environment from wastes and other materials associated with non-coal mining. In September 1990, meetings were held with public interest groups and the mining industry to discuss their comments on Strawman II. By early 1991, the EPA expects to make a decision on how to proceed with program development.

Jan 1, 1990

By E. L. Fidler, T. E. Finch

Wayne Anderson Regarding the technical paper by Thomas E. Finch and Edward L. Fidler, "Recovery of Stray (Thin) Seams in Western Coal Mining." I would like to comment on this subject. In western Canada, most strip mines encounter thin seam coal or rider seams. Although the paper addresses the problems and costs associated with the recovery of this coal, it does not take into account what the savings are. Without looking at the savings, the "Total Objective" is of course not clear. I feel that in a stripping operation the mine can spend per ton (of the thin seam) up to their dragline stripping costs per ton to recover a rider seam or thin seam. The reasoning behind this is simply that this is the price the mine will have to pay to expose an equivalent amount of coal without the recovery of these thin seams. If the mine can recover a rider seam or thin seam for less than the dragline operating costs per ton, a savings will be realized. By recovering a thin seam or rider seam, the life of an ore body is extended by that amount of coal not thrown away. In addition, the cost of land acquisition, associated permits, capital, and reclamation will be reduced as more coal is delivered for a given area. When the above points are considered, the recovery of these thin seams can be very profitable and indeed worth recovering.

Jan 11, 1982