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By A. Simon, J. Weyer, J. Brune, V. Zhiteneva

"Reiche Zeche is a lead-zinc-silver deposit in Freiberg, Germany, that was mined for over 800 years. Since 1969, Reiche Zeche has been a teaching and research mine with numerous adits for dewatering large amounts of inflowing water. Infrequent metal water quality monitoring in the 1980-1990s and flooding of the mine in 2002 led to a lack of relevant data. New measurements were taken at different level adits and ore veins for comparison to historical values, revealing pH levels as low as 1.95, conductivity as high as 22000 µS/cm, and an overall trend towards less acidic waters. INTRODUCTION Reiche Zeche is part of the Himmelfahrt Fundgrube, a former iron ore mine in Freiberg, Germany, in the Erzgebirge mining region of Saxony. The polymetallic sulfide ore found in Freiberg was mined from 1168 to 1969, and though it is no longer producing ore, Reiche Zeche remains as a teaching and research mine for the Technische Universität Bergakademie Freiberg. The most important ore minerals mined were sphalerite, galena, pyrite, chalcopyrite, and silver, and important gangue minerals include calcite, fluorite, barite, siderite, and quartz (Zänker et al 2002). Over one thousand ore loads were mined from this region during operation, which was ceased in 1969 after the lower part of the 700 meter depth was flooded, leaving only the top 200 meters under the surface open for research and teaching. Mined materials from this region can be separated into high grade ore and waste rock. High grade ore, composed of pyrite, sphalerite, galena, chalcopyrite, and arsenopyrite, was brought to surface for smelting during mine operation, and spaces were backfilled with waste rock, which is the primary site of sulfide oxidation and acid mine drainage (Haubrich and Tichomirowa 2002). The waste rock includes remnants of ore from ore loss, veins which were too small to mine, or ore minerals within host rock. Waste rock is primarily composed of biotite gneiss, with sulfides including jarosite, gypsum, minor anglesite, scorodite, and sulfur (Haubrich and Tichomirowa 2002). When weathered, the gneiss forms clay minerals such as illite and kaolinite (Haubrich and Tichomirowa 2002)."

Jan 1, 2016

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

Jan 1, 1996

By James W. Bass

Introduction Atmospheric fluidized bed combustion (AFBC) is an improvement over coal-fired boiler design. It offers several advantages over conventional boilers. AFBC can meet sulfur and nitrogen oxide emission regulations without the need for add-on flue gas treatment equipment. The relatively low combustion temperature inhibits ash melting, thus reducing slagging and fouling that can in turn increase a boiler's fuel flexibility. AFBC process The fluidized bed boiler that operates at atmospheric pressure on the fire side (AFBC) is relatively simple and no different in purpose from those pulverized coal boilers used by utilities today. Fluidized bed boilers can generate steam at the pressure and temperature needed by modern steam turbines. Only the firing system is different. In fluidized bed combustion, the fuel can be almost any coal or waste fuel. It is burned in the presence of a bubbling bed of limestone. Air is forced through the bed at a velocity sufficient to support the weight of the bed particles. When the bed is fully fluidized, it bubbles like a boiling liquid. Although the burning coal makes up less than 1% of the fluidized bed, all the bed particles are heated quickly by the turbulence. The calcium in limestone reacts with sulfur dioxide produced in coal combustion to form calcium sulfate in a dry solid state. In this way, sulfur emissions regulations can be met without installing flue gas desulfurization equipment. Boiler tubes submerged in the bed absorb heat directly from the turbulent solids. The heat converts water in the tubes to steam or superheats the steam. Because of the intimate contact of the boiler tubes with the fluidized bed, heat transfer is highly efficient. Consequently, less boiler tubing surface is needed to generate the same amount of steam as in a comparable pulverized coal boiler. The optimum temperature for sulfur capture is relatively low, about 815°C (1500°F) as opposed to 1370°C (2500°F) for pulverized coal boilers. This results in the formation of lower levels of NON. Because operating temperatures are below those that fuse coal ash, a single design can burn a variety of coals without slagging or fouling problems. TVA's AFBC development program Tennessee Valley Authority's (TVA) involvement in AFBC development began in 1974 and has addressed the technical uncertainties through a comprehensive program of design, experimental, and analytical studies. In 1979, TVA and the Electric Power Research Institute (EPRI) developed plans for a 20-MW AFBC pilot plant, a 10-fold scale-up over the next largest test facility. Pilot plant design features TVA constructed the pilot plant at the Shawnee Steam Plant near

Jan 4, 1986

By D. Diggins

Experimental apparatus for the determination of powder wettability is described. The principle of the technique is based on the measurement of the equilibrium capillary pressure in a packed bed of particles. Both the macroscopic solid-solution-vapour contact angle, e, and the specific surface area, A(m2g-1), of the powder, can be obtained. Experiments on angular quartz particles have been performed. A wide range of situations have been covered: hydrophobic and hydrophobic particles wetted with water, a variety of organic liquids and solutions of surfactants. The results show that reliable and reproducible values for 0 and A for angular and relatively coarse powders can be obtained with the proposed equipment for advancing liquid fronts in the absence of soluble surfactants. In the latter case and for receding liquid fronts in general, only qualitative trends have been obtained.

Jan 1, 1992

By Ronald J. Doll, John Elkin, M. P. Evans

The application of "Alignment Free” right angle shaft mounted drive systems offers improved reliability and reduced costs for surface and underground belt convey- ors. Comparisons to conventional approaches will cover installation, operating, maintenance, and spares inventory cost savings. Various options for belt acceleration and load control on fixed and variable length (booster) belt conveyors will be reviewed for operating performance, reliability, and total cost. Lastly, a case study of a successfully operating installation will be highlighted.

Jan 1, 1996

By George L. Atwood

The Monsanto Company's Henry Mine is located 17 miles northeast of Soda Springs, in the southeast corner of Idaho. Ore being mined is phosphate rock which lies in the Permian Phosphoria formation. The ore is the raw material for Monsanto's three furnace elemental "P" plant near Soda Springs. The finished product from the furnaces is elemental phosphorus which is subsequently used in the manufacture of detergents, food preservatives, fire retardants and other consumer items. Mining is by open pit methods using 0-9 crawler tractors to rip and push-load rubber tired scrapers in stripping and mining operations. The equipment spread consists of six D-9G crawler tractors, four Caterpillar 6578 scrapers, eight Euclid S-24 scrapers, one Reich T750 drill and one Caterpillar No. 16 patrol plus various support equipment. Stripping is performed on a 12-month basis, two shifts per day. Mining is performed mainly in the summer months on a one shift basis. The hauling season begins May 15 and ends November 1 due to freezing weather and snow conditions. Annual production is 1,000,000 tons of phosphate rock and 2,500,000 to 3,000,000 yards of stripping. Stripping, mining and hauling is performed for Monsanto by Dravo-Soda Springs, a mining contractor. Dravo-Soda Springs owns, operates and maintains all equipment used in stripping, mining and hauling. The contractor is paid for stripping by the bank yard and for ore mined and hauled on a tonnage basis. The Monsanto elemental phosphorus plant began production in 1952 with ore being trucked to the plant from the Ballard Mine. Haulage was over public roads in 15, 24-ton semitrucks. A private haul road was constructed from the Ballard Mine to the Monsanto Plant in 1958 and 1959 to accommodate trucks with two twenty-yard trailers. This 11/ mile road was first used in the 1959 hauling season. In 1965, five new Kenworth tractors with two, 'forty yard trailers were introduced into the haulage system. These units carried 120 ton payloads and were used until

Jan 1, 1972

By D. G. Klaren

Self-cleaning fluidized bed heat exchangers are conquering the world for reason that they are able to solve any severe fouling problem in indirect heat transfer due to the circulation of cleaning particles through the tubes of vertical shell and tube exchangers. In most cases, these particles consist of chopped metal wire. Moreover, self-cleaning fluidized bed heat exchangers perform with excellent heat transfer at very low liquid velocities, which makes completely new designs of shell and tube configurations possible. Further, self-cleaning fluidized bed heat exchangers show a strong shear thinning effect in non-Newtonian liquids. All the above characteristics make the self-cleaning fluidized bed heat exchanger an ideal tool for the indirect heating of laterite nickel slurry in High-Pressure-Acid-Leach (HPAL) plants. Preliminary tests and evaluations of these heat exchangers have shown that the performance and price of these heat exchangers used for the production of nickel and cobalt from a laterite slurry, cannot be matched by existing conventional heat exchange systems. This article explains the principle, design, lay-out and enormous advantages of the self-cleaning fluidized bed heat exchange technology in a plant suitable for an annual production of approx. 45,000 ton nickel and 4,500 ton cobalt from laterite slurry through high pressure'acid leaching.

Jan 1, 2002

By M. J. McPherson, P. Mousset-Jones, G. Danko, F. Calizaya, K. You

The friction factor is one of the more difficult parameters to determine in ventilation planning. In practice, this can be estimated from published factors such as those of McElroy. The problem with this approach is that the selection requires some judgement, and the estimated values offer no more than guideline accuracy. This study, examines the effects of four factors on the coefficient of friction for a simulated mine airway. The factors are: airway cross-section, asperity height, flow direction, and cross-cut spacing. The study includes the modeling of a mine airway and the evaluation of the results from 13 experiments on flows of air over rough surfaces. The model, physically represented by a wind tunnel, includes a rough surface section which can be modified to simulate mine airways of various shape and asperity height. Most of the experiments were performed under controlled flow conditions during which the Reynolds number was varied between 50,000 and 300,0000. Based on this study, the friction factor for a mine opening was found to depend not only on the size and shape of the surface asperities but is also affected by the orientation of them in relation to the flow direction.

Jan 1, 1991

By J. Dubbert, T. H. Jones

"This paper describes a rib-control methodology that uses standing support to provide most of the lateral resistance to the rib. The method is analyzed, and its boundary conditions for rib control are described. In this method, an animal-fencing mesh product covers 80 percent of the rib surface and is sparsely bolted to the rib. Can supports or other similar stiff supports are installed primarily as roof support for the entry. As the rib spalls and dilates, the mesh catches the material and expands, pressing against the standing support. Mining proceeds, and vertical roof loads increase the normal force on the Can supports, causing friction at the top and bottom of the support to go up, thereby improving lateral resistance to rib swelling.At one mine in the western United States, this method has proved excellent at preventing the buildup of rib spall. It substantially reduces the number of bolts used for screen installation, improves installation efficiency, reduces manual labor and provides more rib coverage than many screening methods. Because standing support is typically part of the roof-control plan in longwall tailgates, no additional standing-support costs are incurred. IntroductionRib safety in underground coal mines is an oft-studied topic because ribs are high-hazard areas. An overview of early rib safety research can be found in Jones and Mohammed (2014). There is a significant difference between rib support and rib control. Support improves safety through the installation of strengthening elements, such as bolts and dowels, designed to reduce rib spalling. Although spall reduction is preferred, controlling how the rib fails is enough to ensure safety in some situations. Rib control uses external elements to provide confinement, thereby holding sloughed material in place, or to prevent falling rib material from striking mine personnel. This paper presents a study of a control method used on the pillar side of a longwall coal mine tailgate in the western United States."

Jan 1, 2015

By Ehsan Alavi, Sanjeer Yogendran, Savreet Singh

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto extends approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. This project includes the installation of five intake shafts connected by 10.5 km of 6.3 m internal diameter tunnel and eleven drop shafts and vent shafts, connected to the tunnel by a series of adits. During the excavation of one of five intake shafts (20 m in diameter and 52 m deep), significant volumes of free phase oil and hydrocarbons were encountered. Due to the heavy inflows of the contaminants, excavation was stopped at the transition depth. The initial support of excavation needed to be redesigned, shaft had to be backfilled with CDF and installation of deeper secant piles are in progress to cut off contaminants. This paper outlines the initial plan for excavation as well as the design changes to the plan. The current status of the shaft excavation and lessons learned will be discussed.

Jun 13, 2021

By C. Opoku-Ware, M. Kukay, P. Conrad, F. Inkoom, R. Pal

Researchers at Montana Tech are investigating the potential for developing trees tolerable to degraded un-reclaimed mine site tailings and soils as a solution to re-establishing long-term tree growth on those sites. This project involves growing tree seedlings from seeds planted in the degraded mine tailings and soils in which they will eventually be planted. The outcome of the project is expected to lead to a successful solution for re-establishing tree growth in degraded tailings and soils in Butte, Montana with minimal post-planting human intervention. Work conducted on the project to date has shown successful growth of seedlings in degraded tailings and soils. INTRODUCTION In an effort to improve Butte Area One natural resources, this research project is working to help restore tree growth in the Butte Priority Soils Operable Unit Boundary (BPSOU) (Opoku-Ware, et al 2018). Research by Blicker, et al (2003) found that, the BPSOU, which is part of the Silver Bow Creek/Butte Area National Priorities List (Superfund) Site within and near Butte, Montana has multiple historic mining sites situated entirely within the urban setting of Butte. Mine wastes and mill tailings, accumulated from over 100 years of gold, silver, and especially copper mining are dispersed throughout Butte, posing health risks to human and environmental receptors. Stabilization of tailings sites is needed to control fugitive dust, prevent run-off of toxic material resulting in subsequent sediment deposition in streams, reducing the volume of water seepage through acidic and heavy metal contaminated material, and improving land productivity and aesthetic values (Watkin and Watkin, 1982). If successful, the project will help restore water quality and maintain stream flow in Silver Bow Creek where it flows through Butte Area One. Trees native to Butte are being grown to seedlings in a greenhouse located on Montana Tech’s campus which will be planted in degraded soils located within the BPSOU. Growing trees is expected to help restore vegetative ground cover within the watershed contributing to stream flow in Silver Bow Creek. The trees will prevent soil and tailings from eroding and being deposited in Silver Bow Creek where they could degrade water quality and choke stream flow. The project combines research with tree seedling growth to provide a resource for Butte that could produce thousands of tree seedlings each year adapted to the harsh climate, soil, and tailings conditions that exist in the BPSOU where they will grow. It is anticipated that the trees developed by the project will have the capability for long-term survival and growth because they will be germinated and grown into seedlings in the degraded soils and tailings collected from the BPSOU where they will be planted. Soils and tailings collected for the project have been evaluated to determine if they lack nutrients or contain substances potentially toxic to the long-term growth and survival of the trees. Toxic levels of metals, high concentrations of soluble salts, extremes in pH, nutrient deficiencies and imbalances, surface crusting, high bulk density, low infiltration rates, high surface temperatures, low cation exchange capacity, restricted microbial activity, low water retention, harsh climatic conditions and surface particle movement are some of the traits of mine tailings sites that restrict revegetation efforts (Barth, 1986).

Jan 1, 2019

By A. W. Wensel

The adsorption behavior of sodium oleate on brucite, Mg (OH)2, has been studied by Fourier transform infrared spectroscopy. Both internal reflection and diffuse reflection (DRIFT) methods were used to characterize the adsorbed oleate on brucite. DRIFT measurements were shown to be quantitative, and an equilibrium adsorption isotherm was obtained. The conformational behavior of the adsorbed oleate was investigated as a function of adsorption density. It was found that at sub-monolayer coverage the alkyl chains of the adsorbed oleate had more ?gauche? character than at multi-layer coverages. Also, DRIFT spectra revealed that the adsorbed species were magnesium dioleate. For internal reflection measurements single crystals of MgO were hydrolyzed to form a thin Mg (OH)2 layer.

Jan 1, 1994

"The Mine Haul Road Optimization Alliance is an Australian industry-academia collaboration which has been developed to support mine haul road operators by fully integrating mine road design research solutions with industry end-user service providers to design, assess, implement and monitor the various equipment, materials and road management strategies required to optimize the safety, environmental and economic performance of a haul road. Initially, a broad overview of the university-industry collaborative landscape is presented, following which the current situation in the Australian mining sector is reviewed both nationally, and on a country-wide basis, internationally. This insight places realization of a collaboration between Curtin University Western Australian School of Mines Mining Engineering and Metallurgical Engineering (WASM ME2) and the Haul Road Optimization Alliance (HROA) industry members into context of opportunity. Following an overview of the HROA collaborative structure, aims and objectives, it is shown how academia and industry can collaborate to deliver a more robust solution to mine haul road design, performance or management needs, especially where integrated solutions are needed. Critically in this approach, implementation and monitoring data provided by industry and service-providers alike forms the foundation on which to develop research knowledge and innovation that is more responsive to the end-user requirements, typically represented by ‘early goals’ and implementable solutions. The paper concludes with examples of how the alliance collaborations work in practice to deliver improved mine haul road designs and optimized operational performance, together with the mechanisms used to ensure industry needs are met through focused, end-user driven research and integrated solutions implementation."

Jan 1, 2016

By W. Collingwood

As open pit mines continue to grow deeper and productivity continues to increase, the management of respirable dust and noxious gases can become a challenge. The natural wind flow in open pit mines is often recirculatory. This recirculation traps dust and gases in deep open pit mines. This problem is particularly acute in high latitude open pit mines due to a phenomenon known as an atmospheric inversion. In the winter, arctic and subarctic regions experience short days and long nights. This deficit of solar radiation creates a situation in which cold, still air accumulates near the bottom of the pit. In open pit mines, this can result in unhealthy accumulations of gases and other contaminants in the open pit mines. In this study, the natural wind flow patterns in and around open pit mines were investigated using a computational fluid dynamics (CFD) program. Two dimensional models were created for a variety of pit geometries. The effect of depth, slope angle, and wind speed on the recirculation pattern in the pit was examined.

Jan 1, 2011

By N. A. Frazier

The technology for using limestone or lime to scrub SO2 from power-plant flue gas has significant implications to the limestone industry. A brief status report on these processes will be made, possible process requirements on the limestone properties will be reviewed, and projections on the buildup of demand with respect to time will be reviewed. Disposal problems inherent with the use of these throwaway processes will also be summarized. Given a viable technology, relations among (1) distance of power plants from low- and high-sulfur coal and limestone deposits, (2) modes of handling and transporting immense tonnages of bulk material-coal and/or limestone, and (3) regional air-quality standards are some of the factors which will ultimately determine the demand for limestone. A discussion of these factors will be presented, with the intent of identifying geographic regions where significant increases in production can reasonably be expected.

Jan 1, 1974

By CORA ROELOFS

While the COVID-19 pandemic has dominated the headlines, another epidemic in the United States has continued apace — the opioid epidemic. Half a million opioid overdose deaths have occurred in the United States since 1999, when the opioid epidemic began. The causes of the epidemic include the rise in prescriptions for opioid pain medications, including for work-related pain. Miners and other occupations identified as physically demanding and at higher injury risk have been found to be at increased risk for opioid overdose [1]. However, awareness of the risk factors that might lead to opioid use, the potential hazards associated with their use, and resources to prevent addiction and death can allow miners to make choices that can reduce these risks.

By CASSANDRA L. HOEBBEL, Emily J. Haas, MARGARET E. RYAN

In recent years, there has been increasing interest in the role that individual factors play in health and safety (H&S) outcomes in the mining industry. Two surveys, one measuring self-reported routine safety performance and one measuring individual perceived competence in the non-routine knowledge, skills, and abilities (KSAs) critical to emergency response, were administered to two samples of mineworkers in separate research studies over a 2-year period (N=2,020 and 696, respectively). Eight demographic items were common to both surveys and their associations with each performance outcome were tested in response to a series of exploratory research questions.

Jan 9, 2022

By P. Eger

Minnesota contains a major low- grade copper-nickel sulfide resource within the Duluth Gabbro Complex. Several companies have actively explored this resource. Open pit mining would be required to develop portions of the resource, and as a result, large quantities of sulfide-bearing lean ore and waste rock would be stockpiled. Although the problems associated with high-sulfide tailings and acid mine drainage are well documented, the leaching characteristics of low-grade mineralized stockpiles must be understood for environmental impact assessment, siting, and planning. The Minnesota Department of Natural Resources and AMAX have cooperated in a research program to study leaching and revegetation -of test stock- piles, Six small (1600 'tons) stockpiles were constructed at the MINNAMAX Project Site and they range in composition from 0.29 to 043 g % copper, 0.075 to 0.09% nickel, and 0.6 to 1.45% sulfur. Two of the stockpiles were covered with mineral soil, one was covered with topsoil, and three were not treated Revegetation plots were established on the piles which received a soil cover. Leachate samples and flow measurements were collected at the base of the piles. Initial results indicate that metal concentrations in leachate samples range from 10 to 10,000 times the concentrations found in the streams of the area. During the first growing season, the test pile covered with topsoil yielded 30% less water than untreated test piles. No reduction in yield was observed for the piles that were covered with the less fertile mineral soil. First-year vegetative growth, expressed as biomass, was four times greater on the-topsoil pile than on the mineral soil piles. The long-term effects of vegetation on leachate quantity and quality continue to be investigated.

Jan 1, 1980

By Lana Alagha, Fardis Nakhaei, Jose L. Corchado-Albelo, Noelia Munoz-Garcia, Michèle Heitz

Sulfide tailings from past and present mining activities are important hosts of critical elements and precious metals. This review paper presented a literature survey on the recovery practices of some critical minerals containing Te from sulfide tailings with a special focus on the physical beneficiation and hydrometallurgical separation methods. Finally, a conceptual framework and possible processing flowsheets were proposed. The findings of this review will be useful for the researchers in the field of geochemistry, mineral processing, and metallurgy to evaluate the separation processes for reprocessing of mine tailings for the recovery of critical minerals.

Feb 1, 2024

By G. L. Ploetz

The lanthanon compounds are becoming increasingly more important for ceramic and allied applications. As the supply increases and the cost decreases, further development of these interesting materials will undoubtedly lead to new applications and an increased demand. Recent improvements in separation processes have lead to high purity in the individual lanthanon oxides. This report includes short discussions on the mineralogy of the ores as raw materials, and on the separation processes required to produce the pure individual lanthanon oxides in useful quantities. To discuss the presently known applications of lanthanon oxides, this general review is divided into the following categories: A. Glasses, Glazes, and Porcelain Enamels. B. Refractories and Abrasives. C. Electronic Ceramics. D. Nuclear Ceramics.

Jan 1, 1960