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By A Pettersson

LKAB owns and operates two of the largest underground mines in the world in Northern Sweden. In Malmberget, with a production capacity of about 30,000 t/day of iron ore, the current main 815 m haulage level is rapidly approaching the end of Its life and plans are being made for its replacement on the 1000 m level. Due to the separation of the orebodies, trucks have been chosen for transporting the ore from the orepasses to the crushers. The trucks currently in use have a capacity of 120 tons. To increase the efficiency of the loaded haul, the new main level will have a favorable slope from the drawpoint locations to the crushers. From the new level the crushed ore will be transported by conveyor to the 815 m level for hoisting to the surface. The paper discusses the planned mining and transportation system.

Jan 1, 1998

By M. R. Shahan, C. E. Seaman, S. E. Mischler, T. W. Beck

"Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce risks of coal dust-fueled explosions. The goal of this NIOSH study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust (<75 µm diameter) in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity. Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing, and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle is operated at high fluid pressures to produce smaller droplets and move more air. These findings can be used to select sprays and design spray arrays to control airborne float dust over the entire longwall ventilated opening. INTRODUCTION Coal mining processes produce airborne dust that naturally deposits on the floor, roof, and ribs of mine airways. These fine dust particles, termed float coal dust when smaller than 75 microns in diameter, are deposited in return entries of coal mines and can be re-entrained by pressure waves induced by methane-air explosions (Rice et al., 1911; Nagy, 1981; NIOSH, 2006). These particles are also those most likely to participate in coal dust-fueled explosions, which can potentiate and propagate explosions resulting in extensive damage. In order to meet compliance requirements of at least 80 percent incombustible content in the composition of material deposited in mine entries (CFR, 2016), coal mines apply an inerting agent, specifically, rock dust (Harris et al., 2009). Should methane be present in the mine atmosphere, the required fraction of incombustible content is further increased by 0.4 percent for each 0.1 percent methane. The removal of airborne float coal dust (AFCD) prior to deposition is an approach intended to make current rock dusting practices more effective by increasing the proportion of inert material to combustible material, resulting in a lower risk of coal dust-fueled explosions. Water sprays are both effective and widely accepted as a method for controlling underground coal mine dust. In fact, water sprays are considered to be the most economical and technically feasible means of reducing dust concentrations in underground coal mines (Courtney and Cheng, 1977; Barker and Humphreys, 1996). Sprays are used in several ways to control dust in mining processes: inhibiting dust formation, immobilizing dust to prevent it from becoming airborne, and capturing airborne dust (Cheng, 1973). Reductions in airborne dust concentrations have frequently been attributed to inertial impaction between water droplets and dust particles, forming larger agglomerates which then quickly precipitate out of the airstream (McPherson, 1993). Inertial impaction activity is generally accepted as the major capture mechanism for airborne particles larger than 0.5 µm in diameter. It is this mechanism that is evaluated in this study."

Jan 1, 2017

By Adrian C. Dorenfeld

The concentrator of Bonneville Ltd.* at Wendover, Utah, processes a feed obtained by, solar evaporation of a brine containing sodium and potassium chlorides with minor amounts of impurities. Salable potassium chloride concentrateis produced from this feed in two steps: flotation with amine reagents to concentrate the potassium chloride, and washing of the concentrate with fresh water to reach final grade. In the flotation step emphasis is placed on recovery, whereas the washing step has as its objective the production of salable grade (in excess of 60 percent K20 equivalent), with recovery being important but secondary Ideally, flotation should give maximum recovery at a concentrate grade which will permit washing to salable grade with a minimum recovery loss, thereby maximizing over-all recovery. Except for this relationship, flotation and washing are two separate and distinct operations.

Jan 1, 1965

By J. R. Sturgul

Computer simulation models of working mines can be of great benefit to the mining engineer. Such models have been used in mine planning (how many trucks/shovels to have, when to add new equipment, etc.), mine design (should a dispatch system be purchased, where is the optimum location for mine equipment, etc.). A simulation model can be thought of as a dynamic representation of the mine and can easily be changed to reflect a wide variety of different situation. Often a major problem for the engineer is how to present the results of the simulation study. Using PROOF(R) animation it is now possible to interface the results of the simulation and project them onto a computer screen in cartoon fashion.

Jan 1, 1993

By A. D. Davis

The historic Homestake Gold Mine at Lead, SD, was closed in December of 2001, after 125 years of operation. Since closure, the mine has been selected by the National Science Foundation as the proposed host site for the Deep Underground Science and Engineering Laboratory. Pumps in the 8000-ft deep mine were shut off on June 10, 2003. Post-closure flooding of the mine has resulted in rising water levels that reached the 5000-ft level in July of 2007. The rate of water inflow into the mine is about 750 gal/min. A plot of water level vs. time shows that the rise has not followed an exponential decay curve. When the pumps are turned on for dewatering, the rate of water-level decline will be monitored. Water in the Homestake mine contains arsenic derived from arsenopyrite. In samples of mine water, the median concentration of arsenic was below the surface-water aquatic life standard for beneficial use.

Jan 1, 2008

By W. de Bruijn

Differential reduction and expansion or shrinkage of hematite under the influence of intimately associated foreign oxides may be a source of stress formation and sinter degradation during blast furnace reduction. To study specific effects, synthetically pre-pared hematite powder evenly doped with 1% by weight of several elements present as oxides, was pressed into tablets and sintered at high temperature prior to reduction. Continuous thermo-gravimetric and dilatometric analyses were per-formed on the sintered tablets as these were being subjected to reduction under simulated blast furnace time/temperature/gas composition conditions up to 1183 K. These findings were coupled with observations on the microstructure of tablets removed from various stages of the reduction process.

Jan 1, 1988

By R. J. Smith

Hornestake&apos;s Mclaughlin Mine is the first commercial application of pressure oxidation pretreatment of gold prior to cyanidation. Inherent to the autoclave process are several liquid/solid separations. Flocculant consumption represents a significant portion of the consumable reagent costs at McLaughlan. This paper focuses on the efforts of the Operating, Metallurgy and Engineering groups to improve thickener operation and minimize flocculant consumption. An operating philosophy incorporating feed solids control, increasing flocculant dilution water and minimizing flocculant solution shear has resulted in a reduction in 1986 flocculant costs of $0.054/t ($0.06 st) versus 1985 costs. Additional changes are projected to result in a further cost reduction of $0.20/t ($0.22/.st) in 1987.

Jan 1, 1988

By O. Lopez

"Stringent regulations and increased arsenic presence in ore bodies being exploited have created the need for cost effective and environmentally compliant technologies to remove selenium and arsenic from mine waters and metallurgical waste streams. Existing treatment methods have high life cycle costs and/or produce residues that, due to their unknown stability over the long-term, may represent future liabilities. This results in high compliance costs and uncertainties which negatively impact existing operations and projects in permitting. Selen-IX™ is a new ion exchange based process that selectively removes selenium from mine impacted waters down to 1 ppb while producing a stable inorganic iron-selenium product. Results of piloting completed on streams generated from coal and copper-gold deposits are presented along with preliminary equipment sizing and life cycle costs of full scale treatment. An example of a commercially available system for arsenic removal using sulphide precipitation is presented. The benefit of this treatment method is discussed based on recently completed technical feasibility assessment including laboratory testing and preliminary engineering design. INTRODUCTION Selenium Due to the chemical similarity between selenium and sulfur, selenium substitutes sulfur in many minerals that can be found in a wide range of deposits including coal, base metal, precious metal, phosphate, and uranium. One of the main environmental challenges facing the industry in North America today is related to the removal of hexavalent selenium, e.g. selenate, to ultralow levels, typically between 1 to 10 ppb, from large flows of often cold water containing less than 1,000 ppb of selenium. Recent studies commissioned by the industry identified biological selenium reduction systems as the best available technology. Although the biological selenium reduction process is commercially proven in certain applications to remove selenium to ultralow discharge levels, the technology has been primarily applied to relatively low and constant flows of warm water produced by the Flue Gas Desulfurization (FGD) scrubbers in the power generation industry. The wide spread adoption of this treatment method by the mining industry is hindered by high capital and operating costs associated with treating large flows of cold water, lack of data and knowledge about the long term stability of solid residues produced by this treatment, and limited capacity of biological systems to respond to sudden changes in flow and/or mass load of contaminants. Furthermore, it has been reported that reaching discharge limits less than 3 ppb could be a challenge and that polishing treatment for the removal of BOD and phosphate maybe required to avoid the impact of the biological treatment which requires organics and nutrients, on aquatic environment downstream of treatment plants. Alternate treatment systems are being developed to overcome and/or completely avoid some of the challenges of biological systems. One such treatment system is BioteQ’s Selen-IX™ process which is purely physico-chemical treatment system."

Jan 1, 2015

By A. Dell’Era, E. Ciro, C. Lupi

The paper explores the recovery of indium via electrowinning from sulfate baths, focusing on the impact of different cathodic supports (AISI 316L and nickel) on process parameters such as electrolyte composition, current density, and temperature. The study compares productivity, morphology, and structure of indium deposits on both cathodes, finding that nickel cathodes generally yield better results.

Nov 1, 2023

By Kristian E. Waters, Hao Ma, Haibei Wang

Heavy metal ions exist in waste effluents including mining tailings, manufacturing discharges, and smelting and metal plating process wastes. Various methods are available to treat industrial effluents containing high levels of metal ions, but when confronted with wastewater that has low metal ion concentration below 500 mg/L, most techniques suffer from low removal or separation efficiency as well as high operating cost. ELM-based techniques can be used to solve these problems.

Apr 1, 2023

By Mark Godfrey, Wickus Slabbert, Debra Miller, Dave Dew

Sao Bento Mlnerai;;ao Mine (SBM), located 100 kms northwest of Belo Horlzante, Brazil, was commissioned In 1987t1l to produce 185 kg per month of gold from 240 tpd of refractory sulphide flotation concentrate. The concentrate Is processed by a Sherrill Gordon design pressure oxidation circuit followed by conventional CIL gold recovery process (Flgur .. J). The original plant design foresaw expansion to 480 tpd, and In this regard the acidic effluent neutralisation, CIL and carbon circuits were designed for future expansion to treat the higher tonnage. The pressure oxidation section was sized for 240 tpd with the Intention to double the Installed plant equipment to provide 480 tpd capacity when required. This decision was based In part on the novelty of pressure oxidation to treat refractory sulphide concentrates in 1984 when the process design was finalised. General Mining, Metals & Minerals (Pty) Ltd (GENMIN), has been actively Involved for the past 30 years in the development of bacterial process for the oxidation of refractory gold concentrates; the results of this development program have provided the registered process BIOx®. The successful Implementation of BIOx® technology for treatment of refractory gold concentrates at GENMIN's Fairview Mine In October 1986t2l, as well as the substantial experience accumulated in laboratory and pilot testing of some 40 other sulphide concentrates, Justified reconsideration of the oxidation process best suited to provide the Incremental sulphide oxidation capacity planned for SBM.

Jan 1, 1992

By C. A. Born

AMAX Inc. climax&apos;s mine-mill complex at Climax, Colorado is best known for its molybdenite production: 50,000 TPY of molybdenite flotation concentrate (95% MoS2) from mill heads containing 0.35% molybdenite. Less recognized are the byproducts that are concentrated from the tails generated in the rougher flotation circuit (see Figure 1). Climax recovers a heavy mineral concentrate by passing the rougher tailings from molybdenite flotation over Humphrey spirals (Figure 2a). This concentrate is floated using xanthate at pH 4 to remove sulfides, principally pyrite. The tails from the pyrite float are then cleaned of quartz, feldspar and light minerals by tabling (Figure 2b). Amine flotation follows at pH 1.5 and 75°C to float monazite (Figure 2c). The present circuit at Climax dries the monazite flotation tailings and utilizes high intensity cross-belt magnetic separation Figure 2d) to generate a high grade wolframite concentrate and a low-grade cassiterite product, both of which are contaminated with the mineral brannerite, (UO, TiO, UO2)TiO3. The uranium specifications have recently become difficult to meet due to the increasing percentage of brannerite reporting in the mill feed. A plant is being built utilizing hot sulfuric acid and sodium chlorate to leach this uranium from the monazite flotation tailings prior to their being fed to the wolframite- cassiterite magnetic separators. This modification is the subject of our paper.

Jan 1, 1975

By C. F. Lee, Bezalel C. Haimson

A 300 m deep test hole at Ontario Hydro&apos;s Darlington nuclear plant site, 65 km east of Toronto, was used to determine the state of stress in the Paleozoic limestones (O-22O m depth) and the Precambrian granitic gneiss (220-300 m). The results of the hydrofracturing measurements indicated a state of high horizontal stress along the depth of boring and a consistent orientation of principal stresses in each geologic unit. These results were confirmed by a borehole TV camera survey, and by overcoring tests. The magnitudes and orientations of the measured in situ stresses were used in a feasibility study of siting an underground nuclear plant, and in particular in the geotechnical design of proposed reactor caverns in Precambrian rocks. Their implications on cavern stability under operational and accident conditions were analytically studied, taking into consideration the potential superposition of thermomechanical stresses under loss-of-coolant condition, and the possibility of thermal spalling in the host rock.

Jan 1, 1979

By F. J. Susko

The US Bureau of Mines is using Fourier-transform infrared (FT-IR) analysis to investigate the bonding mechanisrn that occurs during the dewatering of clay slurries. High-molecular-weight polymers are used as flocculating agents in these processes. This investigation presents the results of an FT-!R study of calcium-exchanged montmorillonite treated with polyacrylamide (PAM) and polyethylene oxide (PEO). Both thin film and attenuated total reflectance (ATR) spectroscopic techniques were employed to study this clay polymer system. Results suggest PAM is adsorbed to the clay via the nitrogen atom of the polymer. A waterbridge is involved in the bonding between the clay at d PEO. Evidence also suggests that PEO may be adsorbed directly onto the surface of the clay.

Jan 1, 1991

By A. K. Bakshi, Komar S. Kawatra

A plant trial of a new on-line pressure vessel rheometer for slurries, developed at Michigan Technological University, was carried out at a nearby copper concentrator. The rheometer measured the flow curves (shear stress vs. shear rate) of chalcocite slurries. Viscosity of non-Newtonian slurries changes with shear rate and so, for such slurries viscosity measurement at a single shear rate (often seen in the literature for grinding and classification studies) cannot be correlated to process performance. For these slurries, viscosity at various shear rates can be measured from flow curves generated by the pressure vessel rheometer. Other rheological properties, such as flow type and yield stress can be determined by this rheometer to better characterize the slurries. The slurry at the copper concentrator consisted of ground chalcocite ore. The solids content in the slurry varied between 30-60 % by weight. Top size of the particles was 125 micron, and 80% passing size was 34 micron. Measurements by the pressure vessel rheometer showed that most of the slurries had pseudoplastic flow at shear rates below -3000 sec-l, where the viscosity of the slurry decreased with increase in shear rate. Above -3000 sec-l, like a Newtonian fluid, the viscosity of the slurry remained steady. Flow curves and viscosity from the pressure vessel rheometer were verified with a Brookfield viscometer and a vibrating sphere viscometer, and the results were found to be accurate.

Jan 1, 1997

By E. Watkins, S. J. Schatzel, V. Gangrade, K. M. Ajayi, Z. Khademian

Longwall-induced deformations could jeopardize the mechanical integrity of shale gas well casings positioned in the abutment pillar of a longwall mine. The in situ and induced fracture networks surrounding the gas well could provide pathways for gas flow into the mine creating safety concerns. Hence, this study by the National Institute for Occupational Safety and Health (NIOSH) develops a discrete fracture network (DFN) model to characterize the fractures in the overburden based on geomechanical analyses of mining-induced fracture apertures at a study site in southwestern Pennsylvania. The apertures from the geomechanical model are used to develop a stochastic DFN model of the site in fracture flow code (FFC). Multiple realizations of the stochastic DFN model that replicate potential fracture geometries are simulated, and the fracture permeability is compared with field measurements. A maximum field measurement of 5.03 × 10− 12 m2 (5080 mD) and 3.82 × 10− 13 m2 (386 mD) was estimated over the abutment pillar at the Sewickley and Uniontown horizon, respectively. The results show that the average permeabilities from the DFN model agree closely with the field measurements. In addition, the comparison of all the field measurements and 100 DFN realizations show the model is representative of field conditions. These findings provide critical information regarding fracture characteristics in the overburden, which will further be used to predict potential shale gas flow to the mine in the event of a casing breach for an unconventional gas well.

Jun 17, 2022

By Georges Cote, Ehsan Alavi, Eren Kusdogan

The City of Toronto's Coxwell Bypass Tunnel is currently being constructed by North Tunnel Constructors (NTC) ULC, a joint venture of Jay Dee Canada, C&M McNally Tunnel Constructors and Michels Canada. This project includes construction of approximately 10.5 km of 6.3 meter finished diameter rock tunnel, five 20 meter diameter storage shafts and eleven tunnel connection drop shafts, along with associated deaeration and adit tunnels. 120 m of Starter tunnel and 70 m of Tail tunnel were excavated with roadheaders to help with the launch of the TBM and as part of the contract base scope work. JayDee Canada in Collaboration with Everest Equipment Co. developed an innovative approach to design and build a stand-alone Ring Machine Erector nicknamed Enterprise to erect precast segmental lining in Starter and Tail tunnels in lieu of Cast-In- Place concrete. This paper describes the design and provides feedback on the innovative procedure used to install the rings.

Jun 23, 2024

By Michael R. Smith

Barrick Goldstrike Mines Inc.’s Betze open pit is located at the north end of the Carlin Trend, in Eureka County, NV. Ten open pit gold mines exist on the trend, which strikes northwesterly, through the north end of Eureka County and into Elko County (Fig. 1). The final pit will be about 2440 m long x 1550 m wide (8000 x 5100 ft), elongate in a west-northwesterly direction and about 425 m (1400 ft) deep. The pit straddles the Barrick-Newmont Gold Co. property boundary. History The first hole at the Goldstrike Mine was drilled in 1962. Between 1963 and 1964, 17 shallow holes were drilled with little encouragement, in view of the price of gold at $1.12/g ($35/oz). From 1962 to 1975, several different companies explored the Goldstrike property. In 1975, Pancana Industries acquired the property. In 1976, Pancana’s exploration efforts found sufficient gold mineralization to initiate heap leach production. In 1977, Pancana formed a joint

Jan 1, 1994

By Hans Ehdwall, Erling Strandon, Friedrich Steinhäusler, Victor A. Leach

INTRODUCTION The basis for any measures in radiation protection is the quantitative assessment of the radiation exposure. Due to the extensive requirement in health physics manpower and related cost it is necessary to develop certain criteria regarding the necessity of monitoring and the selection of population groups to be monitored. Depending on the overall objective of the particular programme, the specific requirements for the measurement of atmospheric levels of radon, thoron and their daughters for practical radiation protection purposes differ significantly for those in the case of research applications, such as use of data for epidemiological studies. As part of the OECD-NEA Programme on Radon Dosimetry and Monitoring Task Group 1 reviewed available models for lung dosimetry in the case of inhalation of radon 222, radon 220 and their daughters (James et al., 1981). Using defined reference atmospheres for underground- and open-pit mining conditions as well as for dwellings, normalized conversion factors were calculated for the mean bronchial dose (mGy) per Working Level Month exposure (WLM). Task Group 2 discussed the features and adequacy of the Working Level (WL)-concept as a physical correlative of the absorbed lung dose and its limits of confidence and accuracy (Johnson and Leach, 1981). The WL-concept was found acceptable for radiation protection purposes provided that modifying factors like particle size, unattached fraction and respiratory minute volume did not cause the effective dose equivalent per WLM as calculated by either the James-Birchall or Jacobi-Eisfeld lung models to be more than 50 % above that given by ICRP of 0.01 Sv/WLM. For application in epidemiological studies the WLconcept is considered acceptable if the calculated absorbed dose to the tissue does not vary by more than 50 % (at the 95 % confidence level) from that given for defined reference conditions. In the following, objectives and requirements for the measurement of radon, thoron and their daughters are discussed for operational health physics routine and special research applications according to the scheme outlined in Fig. 1.

Jan 1, 1981

By Glenn A. Shirey, Robert D. Stoessner, S. Gopalakrishnan

Under a contract awarded by the U.S. DOE-PETC, the Pennsylvania Electric Company and New York. State Electric and Gas Corporation are conducting a test program to evaluate and optimize the performance of a two-inch air-sparged. hydrocyclone (ASH) for cleaning fine coal. The test program is being conducted at the Homer City EPRI Coal Quality Development Center, utilizing Upper Freeport coal classified to minus 0.15 mm as the process feed material. A matrix of experiments has been conducted to establish the influence of significant design and operating variables (including overflow and underflow orifices, inlet slurry pressure, airflow rate, and reagent dosage) on the production of deep cleaned coal. Performance of the ASH is being compared to conventional froth flotation, utilizing advanced techniques and selected flotation reagents. This paper focuses on work completed to-date to optimize the performance of the air-sparged hydrocyclone for cleaning fine coal. INTRODUCTION The Pennsylvania Electric Company (Penelec) and New York State Electric and Gas Corporation (NYSEG) have been evaluating advanced fine coal cleaning processes for the production of compliance grade coal (1.2 pounds S02/million Btu). Laboratory bench-scale froth flotation results were compared with results of advanced flotation processes as performed by various organizations, utilizing the same coal feed. Among the processes evaluated, the air-sparged hydrocyclone (ASH) - developed by Dr. Jan Miller at the University of Utah - was considered to offer the best potential for retrofitting into an existing coal preparation facility because of the increased capacity per unit volume. The ASH has been shown to process over 100 times the throughput of conventional froth flotation cells. In May of 1988, Penelec/NYSEG was awarded a contract from the Department of Energy&apos;s Pittsburgh Energy and Technology Center (DOE-PETC) to optimize the performance of a five cm (two inch) ASH for producing compliance grade coal from raw classified minus 0.150 mm (1.00 mesh) Upper Freeport coal, and to compare its performance with conventional froth flotation utilizing advanced techniques and selected flotation reagents. The test work is being conducted at EPRI&apos;s Coal Quality Development Center (CQDC) in Homer City, Pennsylvania, utilizing a circuit processing 0.10 to 0.25 tons of coal per hour. Other members of the Penelec/NYSEG contract team include the University of Utah, Advanced Processing Technologies, Inc., Davy Dravo, Kaiser Engineers, Ebasco Services, and Management and Technical Systems. ASH DESCRIPTION AND OPERATION The ASH-2 System is a five cm ID (actually 4.76 cm) air-sparged hydrocyclone manufactured by Advanced Processing Technologies, Inc., under license from the University of Utah, for the purpose of research, evaluation and development. A schematic drawing of the air-sparged hydrocyclone is presented in Figure 1. Basically the air-sparged hydrocyclone consists of two concentric right-vertical tubes, a conventional cyclone header at the top, and a froth pedestal at the bottom. The inner tube is a porous tube through which air is sparged radially. The outer nonporous tube simply serves as an air jacket to provide for even distribution of air through the porous inner tube. The slurry is fed tangentially through the conventional cyclone header to develop a swirl flow in the radial direction. Air is sparged through the jacketed, inner porous tube wall and is sheared into small bubbles by the swirl flow. Hydrophobic particles in the slurry collide with these bubbles and, after attachment, are transported radially into a froth phase which forms on the cyclone axis. The froth phase is stabilized and constrained by the froth pedestal, thus moving towards the vortex finder of the cyclone header and discharged as an overflow product. Hydrophilic particles generally remain centrifuged in the slurry phase and are discharged as an underflow product through the annulus created by the froth pedestal.

Jan 1, 1989