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Reclamation of surface mines is a crucial environmental issue and a key challenge to the worldwide mining industry. One of the goals of reclamation is to ensure that the area is left in a condition permitting safe future use. Hence, the reconstruction of open pits, waste piles and tailings dams must satisfy appropriate geotechnical stability and safety conditions for the planned use. Landscaping in the final stages is highly relevant as the topography around the mining areas is sometimes dramatically modified by ore extraction. The reclamation strategies must be applied not only after ore exhaustion, but also during its extraction. This is a sound business strategy that leads to considerable environmental benefits and increased security of the mining operations.

Jan 1, 2003

By R. M. Carland, F. F. Aplan

The ion-exchange capabilities of natural zeolites from the western United States, representing the species chabazite, clinoptilolite, erionite and mordenite, have been studied because of their potential use in environmental remediation and in hydrometallurgical processes. These raw zeolite samples were found to contain Na+, K+, Ca+2 and Mg+2 as exchangeable cations, and all of these, with the exception of Na+, were found to seriously interfere with the exchange of Cu+2 from solution. Placing these zeolites in the Na+ form was found to increase their cation-exchange capacity, often massively. In addition, the elution of Cu+2 from the Na+ pre-exchanged zeolite is greatly facilitated when the deleterious K+, Ca+2 and Mg+2 have been largely expelled. The relative influence of these deleterious ions on the uptake and elution of Cu+2 was determined.

Jan 1, 1996

By R. Latifovic

Assessment of the possible impact of existing and future mining projects located in remote areas may be difficult and costly. This may have an adverse effect on the process of issuing mine permits and development of new mines. A remote sensing based land cover change assessment methodology presented in this paper is a promising avenue to render this process more meaningful, precise and affordable. It has been applied to a case study of the Oil Sands Mining Development in the north-east of the Canadian province of Alberta. Recently, the Athabasca Oil Sands Region (AOSR) is a place of unprecedented growth of open-pit mining operations. This study was focused on the primary impact onto the landscape and vegetation resulting from exploration and, mining development. This impact was assessed using an information extraction method applied to two LANDSAT scenes. The analysis based on derived land cover maps shows a 8.64% decrease of natural vegetation in the study area (715,094 ha) in 2001 relative to 1992. It is demonstrated that the methodology presented here provides reliable results and is fully applicable for the assessment of the environmental impact of large scale mining operations.

Jan 1, 2006

By C. Sachanidis

From the surface mines of Ptolemais basin 48 samples of Pliocene lignite were collected. The samples were analysed using Instrumental Neutron Activation Analysis (INNA) and Inductively Coupled Plasma (ICP) for determining the concentrations of 39 trace elements. The contents of sulphur and ash and the loss of ignition were also determined. The chemical affinity of these trace elements was estimated based on 40 correlation diagrams between the elements concentrations and the ash content of the collected lignite samples. According to the obtained results, 18 elements have inorganic affinity (Co, Cr, Cs, Hf, Sc, Th, La, Ce, Nd, Sm, Eu, Yb, Lu, ?n, Ba, ?, Sn, ?r) and 10 elements have inter-mediate affinity (As, U, ?r, Pb, Cu, Sb, Sr, S, Ni, V). The remaining 12 elements (Au, Ir, ??, Rb, Se, Ta, W, Tb, Ag, Cd, Bi, Be) exhibited concentrations below the detection limit. Thus, they were impossible to be classified in a specific affinity group. Based on the classification of these trace elements and sulphur in inorganic and intermediate affinity groups some useful conclusions are drawn regarding their behaviour during lignite combustion and lignite ash utilization and disposal processes.

Jan 1, 2006

By S. G. Malghan, J. P. Van Dillen

Introduction Some uranium minerals are paramagnetic and hence are amenable to concentration by high gradient magnetic separation (HGMS). This paper describes effects of the HGMS parameters-pulp velocity, field strength, matrix loading, and magnetic field gradient-on the product recovery and grade. Unsatisfactory separation of uranium minerals by HGMS is related to ore-specific properties, such as lack of liberation, fine dissemination of uranium minerals, uniform distribution of magnetic minerals throughout the ore matrix, and interference of fine-sized slimes. Experimental techniques to identify and resolve some of these problems are outlined. HGMS of Uranium Ores The mechanism by which uranium minerals are attracted to a magnetic field is either due to its magnetic susceptibility or its association with other minerals that are magnetic. Data on magnetic susceptibility of uranium minerals are scarce. The only reported data are for uraninite at 2360 X 10-6 cm3/mole. Povarennykh (Andres, 1976) concluded that the magnetic properties of minerals depend on: • Structure of the outer electron shell in a mineral with electropositive atoms; • Valence of the atoms; • State of the chemical bonds; • Type of coordination; and • Proportion of magnetic atoms (Fe, Mn, Cr, and Ni) in the composition of the mineral. However, information on the magnetic susceptibilities of the constituent atoms of a mineral alone does not suffice for evaluating the mineral compound as a whole. Most often, uranium minerals can be beneficiated by HGMS if they are associated with other minerals that are magnetic. This appears to be a more predominant mechanism by which the uranium minerals are beneficiated. Experimental A Sala-HGMS (Malghan and Subramanian, 1981), model 10-15-20, separator was used in the experiments. The matrix material-ferromagnetic stainless steel in the form of expanded metal or steel wool-was packed into a 38-mm (1.5-in.) diameter by 360-mm (14-in.) long canister. The matrix material occupied only a 150-mm (6-in.) length. The experimental set-up and slurry flow direction are described elsewhere (lannicelli, 1976). The response of uranium ores in the HGMS was studied by feeding well-dispersed slurry at 10% solids and examining the influence of process variables on selectivity and overall uranium recovery. The chemical and mineralogical characteristics of the ores under study are presented in Table 1.

Jan 12, 1983

By Michael L. Clar

Reclamation of surface mined lands has two basic objectives: (1) the elimination or abatement of undesirable environmental conditions, and (2) the restoration of mined land to its former or more productive uses. This paper addresses some of the planning concepts and site factors that influence the selection of suitable land uses for surface mined lands. Three planning concepts included in the discussion are: (1) mine land planning, (2) comprehensive land use planning, and (3) environmental site planning. The site factors that will influence the selection of an appropriate land use have been grouped into three categories: (1) legal, (2) geographic, and (3) natural. The natural factors are further subdivided into three groupings: geomorphology, soils, and climate.

Jan 1, 1981

By D. Gignac, P. A. Studemeister, H. Koza

Two epiclastic horizons in an Archean volcanic sequence host the gold occurrences on the Dunraine property near Wawa, Ontario, Canada. The Grace horizon of cherty and pelitic tuff strikes north-northwest and dips east. Native gold occurs with arsenopyrite in bedlike and podlike bodies of quartz lenses and stringers set in a pelitic matrix. The Parkhill horizon of lithic graywacke with associated flow-breccia strikes southwest and dips south. Native gold occurs with minor sulfides in similar bodies of quartz erratic within the Parkhill horizon. The auriferous bodies occupy paleotopographic channels and troughs within the two horizons. The former producers are the Parkhill mine with 1689 kg (54,300 oz) Au, Darwin mine with 473 kg (15,200 oz) Au, and Van Sickle mine with 48 kg (1536 oz) Au between 1902 and 1944. The gold occurrences are syndepositional with the host volcanic sediments laid during a pause in explosive volcanism. Fumaroles along steep gullies on the flank of a subaqueous volcanic center precipitated aprons of auriferous silica-sulfide mud. Downslope slumping resulted in exhalative debris flows; gold concentrated in flexures and depressions along stumpage channels. Renewed explosive volcanism covered the auriferous sediments with pyroclastic tuffs, arresting the slumping of in situ fumarolic deposits.

Jan 9, 1985

By David Mast, Irwan Halim, Brian Hagan, Kaveh Talebi, Jason Edberg, Amanda Foote

On June 14, 2023 Jay Dee Contractors’ Tunnel Boring Machine (TBM) “Phoenix” holed through and completed mining the second drive of the I-75 Segment 3 Storage and Drainage Tunnel. Completion of the tunnel came only after overcoming several challenges, including a groundwater intrusion event which deposited thousands of cubic yards of wet ground material into the tunnel. This paper will discuss the events which delayed completion of the tunnel by over nine months, the risk management and construction approaches assumed by the Design-Build team during bid, several challenges faced by Design-Build teams when building stormwater resilience tunnels using traditional Department of Transportation standards, and recommendations for improving risk allocation and proposal documents for future similar Design-Build tunnel projects.

Jun 23, 2024

By F. T. Paleari

Radial gas holdup profiles have been measured in a 50x400 cm flotation column using a multi-cell conductivity probe. Three different bubble generation systems were examined: up to eight vertical filter cloth spargers, three horizontal filter cloth spargers, and three (horizontal) Cominco-type spargers. The variables tested were: number of spargers, symmetry of their arrangement, and height above spargers. Batch water with up to 20ppm frother concentration was used. The general observation is that the profiles tend to be uniform (i.e. flat) with some exhibiting a slight wavy shape. The vertical sparger arrangement proved the most difficult to achieve profile symmetry. The horizontal spargers gave uniform profiles at right angle to their length but a decreasing gas holdup along their length; the Cominco-type spargers gave slightly less scatter in the data. Switching off selected spargers (to simulate malfunction) did not produce strong asymmetry in the profiles.

Jan 1, 1993

By P. A. Schmitz

The characteristics of gold leaching from carbonaceous matter by sodium cyanide, and sorption of gold cyanide to carbonaceous matter in autoclaved and non -autoclaved gold ore from Barrick Goldstrike Mines Inc. (BGMI), Nevada, was investigated. Much greater gold cyanide complex sorption was observed for the carbonaceous matter in high preg-robbing ores relative to the low preg-robbing ores. This observation corroborates previous reports that have attributed observed preg-robbing behavior to the carbon in the ore. Gold cyanide complex sorption was found to be reversible for carbonaceous matter from low preg-robbing ore, but was irreversible for carbonaceous matter from high preg-robbing ores. Autoclaving the ore appeared to enhance the sorptive behavior of the carbonaceous matter from both high and low preg-robbing ores.

Jan 1, 1999

By Raghoottama S. Pandurangi, Mohindar S. Seehra

A critical examination of the published results on the hemolytic ability of different forms of silica viz, quartz, cristobalite, tridymite and amorphous silica is made and it is concluded that quartz, cristobalite, and tridymite have nearly equal longterm abilities (within ±15%) but much larger than the hemolytic ability of amorphous silica when correctly compared on a per unit surface area basis. Also, a one-to-one correlation appears to be valid between the hemolysis and fibrosis studies. New results on the photoacoustic spectroscopy of amorphous silica particles heat-treated at 100, 200, 400, 550, 700, 820 and 1050°C are presented and it is observed that the intensity of the sharp silanol band at 3745 cm-1 and hemolysis by these particles have nearly the same temperature dependence. In contrast the intensity of the bulk IR modes (viz. the 797 cm-1 band) does not show any significant temperature dependence. These observations demonstrate that the surface SiOH species are involved in hemolysis by silica particles. Key words: silica polymorphs; hemolysis; silanol species

Jan 1, 1991

By Gerald P. Kelton

Over the past quarter of a century, the success of the hydrocyclone as a classifier in closed circuit grinding installations has permitted the introduction of the cyclone into virtually all fields of wet industrial processing. Research and experience gained in these applications have established the optimum cyclone sizes and designs necessary to provide the required performance. Although cyclones are used in widely diverse liquid-solid applications, their use for ultrafine separation clearly demonstrates the importance of a familiarity with previous case studies. Krebs Engineers is firmly dedicated to serving the process industry and has acquired the unsurpassed knowledge and experience to handle all types of separations and classification problems. Cyclones have been used for a number of applications to make what might be considered fine separations. A typical example is in an iron ore grinding circuit where a 381 mm diameter cyclone will classify an overflow product to 85% -44 micron. There is no question that this is a fine separation, but still finer separations are possible, and these are known as ultrafine separations.

Jan 1, 1983

By M. Fig, B. Treffner, J. Brune, C. Strebinger, G. Bogin, D. Pardonner

"Methane gas explosions in a longwall coal mine can originate from in or around the gob and can seriously harm nearby workers and equipment. In order to fully understand the explosion flame and pressure wave propagation in the mine, it is important to investigate methane flame propagation in confined spaces as well as flame interaction with rock rubble and other mine structures. The latter can lead to enhanced turbulence causing high-speed deflagrations and/or detonations. Researchers ignited methane-air mixtures in horizontal, cylindrical reactors that contained inserts to simulate various gob characteristics. Rock surface topology and ignition location were investigated. Results show rock surface roughness increased fluid motion, thereby increasing methane flame front propagation velocity, overall pressure rise of the explosion, and time of pressure decay. Moving the point of ignition away from the open end of the reactor resulted in an increase in peak overpressure and an overall pressure rise of the explosion. Experiments were used to validate a computational fluid dynamics (CFD) combustion model that will be incorporated into a mine-scale explosion model to simulate and predict explosion hazards of large scale methane gas deflagrations in longwall coal mines. INTRODUCTION Coal mining is an integral part to our global society with coal-fired power plants providing about 40% of our global electricity [1]. A common method of extracting coal underground is by longwall mining. Researchers and investigative reports have found that explosive gas zones of methane-air mixtures can form along the longwall face and within the longwall gob, presenting an explosion risk to nearby workers and equipment [2]. In an explosion, the resulting flame and pressure wave presents a fatal traumatic injury hazard and can cause serious damage to equipment. In order to evaluate and mitigate the explosion risks in longwall coal mining, researchers at the Colorado School of Mines are developing a coupled CFD and combustion model of a longwall coal mine. The purpose of the model will be to better predict the explosion hazards under various mine conditions in order to build stronger prevention and mitigation strategies for miners."

Jan 1, 2018

By Keith G. Wallace, Malcolm J. McPherson

In order to model accurately a mine ventilation system in an existing mine, it is necessary to determine the resistance to airflow in all main airways. This is accomplished by measuring the airflow and pressure differential in each airway. Gauge and tube methods have been used to determine pressure drops in ramps and level airways. However, it has rarely been used in evaluating the frictional pressure drop in shafts. Because shafts commonly have the highest pressure loss in mines, it is critical that the resistance of these airways be determined accurately. This paper describes the theory and practice of using the gauge and tube method for determining the pressure drop in shafts. The pros and cons of using this method are discussed as well as a comparison between the gauge and tube and barometer measurement techniques. Case studies showing the accuracy of shaft gauge and tube measurements are also presented.

Jan 1, 1991

By Zhiyuan Shen, Dan Zhao

The abstract discusses the importance of reliable mine monitoring systems for preventing accidents. It focuses on diagnosing ventilation system failures caused by roadway faults that alter airflow resistance. The paper proposes using an improved Support Vector Machine (SVM) method to identify the fault location based on changes in air volume detected by wind speed sensors. The approach involves building a sensitivity 0-1 matrix and establishing a roadway fault scope library. The improved SVM method is tested on the Daming coal mine, demonstrating its effectiveness in diagnosing fault locations, reducing training time, and improving accuracy compared to traditional SVM.

Apr 5, 2022

By D. M. Hausen

Carbonaceous gold ores are ubiquitous to virtually all of the Carlin-type gold deposits along the Carlin gold belt in north central Nevada, representing the unoxidized "zones" of presumably extinct thermal spring systems of mostly Tertiary age. A period of subtropical weathering resulted in deep sub-lateritic zones in most deposits to several hundred feet below surface. Carbonaceous ores below this supergene profile of weathering have been investigated by various methods, including petrographic study, standard geochemical and organic carbon analyses, carbon and hydrogen isotopic ratios, electron-spin resonance spectra, infrared spectra, and DTA techniques. Results have been integrated with recent findings by other investigators utilizing fluid inclusion and thermal brine data to indicate a first phase hydrothermal solution temperatures and pressures at a minimum depth of 6 km under normal geothermal gradient. This phase resulted in the quartz-barite-calcite vein filling of the host rocks. Gold mineralization took place later at shallower depths. Primary organic material in carbonaceous ores from the Carlin and other mines appears to be a pyrobitumen residue derived from an old oil pool that had been heated by the thermal solutions, and from which the light hydrocarbon fractions were removed. Some of the bitumen was remobilized along silicified veinlets in the ore, but its role in the emplacement of the gold, itself, is not clear. The gold was localized submicroscopically in fine pyrite, mostly in framboids, and as fine metallic particles, but does not appear to be concentrated within the carbonaceous matter per se. However, reducing conditions associated with bituminous residues are believed to have been favorable for gold deposition.

Jan 1, 2013

By P. K. Chatterjee

Computer aided design and inter active graphics have been well established in the electronics, automotive and mechanical engineering industries. The use of such aids in underground mine design and planning, however, has been noticeably absent. The large expense involved in the research and development of CAD and graphics systems and their highly specialized techniques have rendered investment in these areas difficult to justify. Optimum mine planning involves an interactive procedure of evaluation of several alternative plans. Generally the development of each mine plan of a given operation can take many man-months. This time constraint on planning precludes any comparative analysis and evaluation of alternatives, thereby introducing the possibility of unrealized gains. This paper outlines the development of a computer aided mine design program utilizing interactive graphics for the design, simulation and scheduling of underground coal mines. The program developed examines exploratory borehole information and produces a structured database of the sampled data. This database is utilized to generate seam sections and different mine layouts. A simulation of mine extraction and production levels and a schedule of proposed alternatives are then performed.

Jan 1, 1984

A study was undertaken to determine the effects of five industrial frothers on the relationship between entrainment recovery and water recovery. The experiments were conducted using a Batequip rectangular 60L steel flotation cell that was run in parallel with the first cell in a copper/silver prefloat rougher circuit. The concentration of the frothers ranged from 2.5 to 8.4 g/t. The experiments were repeated at three different froth depths. A power function was found to fit this relationship with no discontinuity in the relationship caused by the changes in frother type and concentration and froth depth.

Jan 1, 2002

By Joao B. Cardoso

This paper describes a two-stage reverse flotation method developed at the Mineral Resources Institute (MRII, University of Alabama, for Kerr-McGee Corporation (KMC), to separate the trona (Na2CO3 ? NaHCO3 ? 2H2O) from a saline deposit containing halite, borax, minor salts, and water insoluble materials. In the first stage, trona is depressed with Quebracho, and the insoluble gangue is floated with fatty acid. In the second stage, trona is floated with cresylic acid. The flotation concentrates contained better than 90% trona with insolubles ranging between 1 and 2%. Although the trona recoveries were low, optimization and middlings recycled in a continuous circuit could substantially increase the value.

Jan 1, 1989

By Douglas E. Pollock

Recent NIOSH published information has shown an increase of rapidly progressive coal workers? pneumoconiosis (CWP) in the southern Appalachian coal region (SAR) of the U.S., despite the fact that compliance data indicates that most coal miners have been exposed to coal mine dust concentrations below the statutory limit of 2 mg/m³. While the exact cause of these elevated CWP levels in the SAR has not been established, several factors may be contributing to the increase in occupational lung disease among coal miners. The mining of high rank coal is known to lead to higher CWP rates, and this type of coal is mined in a portion of this region. Also, a high percentage of the mines in the region are on reduced dust standards because of the high silica content of the airborne dust resulting in miners possibly being exposed to excessive amounts of respirable silica dust. Exposure to excessive amounts of respirable silica dust can lead to silicosis, a disabling and potentially fatal lung disease. NIOSH?s Respiratory Hazards Control Branch has been investigating the possible causes that would account for the observed higher trends in disease progression through literature review, data analysis and in-mine surveying. The investigation to date has revealed that underground mines are faced with cutting large amounts of rock in order to maintain haulage clearances. Cutting rock not only increases the potential for silica exposure, it increases the requirement for machine maintenance, which was a concern observed during dust surveys conducted by NIOSH. Over half of the mines operating in the SAR are on reduced standards due to high silica content. Adequate face ventilation of the continuous miner and roof bolter and limited down-wind operations from the miner are also issues of concern and items that require the constant attention of miners operating in these conditions.

Jan 2, 2010