Search Documents

By D. Govender

In recent years, economies of scale have continued to drive copper projects to larger throughputs to offset depleting lower grade resources. A decade ago, there were only a small number of projects that stretched beyond 100 kt/d (110,000 stpd) throughput rates. Today, and moving forward, virtually all the major copper projects are sized beyond this, with throughput rates up to 250 kt/d (275,000 stpd) now under evaluation for a number of key projects in Chile and Peru. This paper explores the development from the 160 m3 (5,650 cu ft) flotation cells, through to the 257 m3 (9,076 cu ft) cells and to the current 660 m3 (23,380 cu ft) machines. The contributions of specific copper concentrators to this growth phase are reviewed in this article. The historical basis of flotation machine scale-up is also briefly discussed. Metallurgical results as well as layout, maintenance and operational aspects are highlighted.

Feb 1, 2014

By F. F. Peng

For a given flotation system, the rate-controlling step in fine coal flotation can be the attachment of bubble to the fine coal particles. The probability of attachment depends upon the surface characteristics and the collector adsorption on the coal particle surfaces. Thus, to further improve the flotation rate and selectivity is to alter the distribution of hydrophobicity on coal particles efficiently by applying the effective means of collector dispersion. In order to enhance the combustible recovery and selectivity of fine coal flotation, and lower the amount of collector used in the fine coal flotation processes, four modes collector dispersion/addition techniques are tested. They are direct liquid addition in pulp (mechanical agitation), ultrasonic energy dispersed collector into pulp, atomized collector into pulp and gasified collector transported by air and formation of collector-air bubbles in pulp. The effect of four collector dispersion/addition methods on the floatability of -600 µ m (-30 mesh US sieve) coal samples from four ranks of coals were studied. The ultrasonic energy dispersed collector and atomized collector flotation processes enhance flotation yield and most significantly improve the kinetics of fine coal flotation. The gasified flotation process can increase the selectivity of separation and decrease the collector consumption due to starvation flotation is achieved in this process. The flotation efficiency of gasified collector process is as high as that of conventional flotation. It is because that the effect of the decrease in the combustible recovery is offset by the increase of selectivity. In addition to flotation experiments, induction times of bubble attachment to the bed of fine coal particles for four ranks of coals are measured.

Jan 1, 1992

By Roshan B. Bhappu

Stimulated by current $0.80 to $1.20 per pound price tag of copper, considerable interest and activity have been generated in the copper mining camps throughout the world, and especially in the Southwestern United States and Northern Mexico copper belt. Under these economically favorable conditions, many of the marginal oxide-copper deposits, as well as newly discovered prospects, are under scrutiny for possible exploitation. For both the known deposits and new prospects, the big question facing the mine operator is the selection of the best method for processing these economically attractive oxide-copper deposits. Several variations of the hydrometallurgical processes are currently available for treating oxide-copper ores which can be mined by the open-pit method. Basically, these processes involve preparing the ore for application of an acid solution, applying the solution to the ore, and recovery of the metal from the pregnant solution. Dump leaching, heap leaching, vat leaching, agitation leaching and, in more recent times, in situ leaching or solution mining in combination with well established cementation process or the newly developed solvent extraction-electrowinning system have all been employed or have been investigated for the recovery of copper from oxide ores. Of these processes, dump, heap and vat leaching have been successfully practiced for treating oxide-copper ores. Agitation leaching is a relatively newcomer and has been adopted from the experiences of uranium and gold processing. Finally, the inplace leaching technique is the latest process to be suggested for possible treatment of oxide-copper ores.

Jan 1, 1974

By S. Lu, J. P. Barta, T. W. Meikle

Three nutrient amendments and a biological seed inoculant were evaluated for use in establishing vegetative cover on waste rock substrates. Randomized blocks were placed on three substrates. Treatments included two types of organic fertilizer, mineral fertilizer, Azospirillum bacterial inoculant, plus controls. The seed mix consisted of native grass species adapted to low nutrient conditions. Canopy cover has been monitored for three growing seasons. Results indicate : 1) two of three substrates support plant growth following amendment with organic fertilizers; 2) organic fertilizers increase cover substantially over mineral fertilizer; and 3)Azospirillum had no effect on canopy cover.

Jan 1, 1999

By Kevin Saeler, Patrick Willaman

Utilizing automation is one way to improve competitiveness. Roof and rib bolting in underground coal mines has not changed significantly for more than 40 years. Most roof bolting is still a largely manual process involving high levels of staff carrying out repetitive work. Roof bolting statistically has one of the highest levels of underground accidents, including finger, hand, and arm injuries. Operators are exposed to falling objects and becoming entangled in roof bolting apparatus while roughly moving awkward 6-ft drill steels and roof bolts. It is estimated that over 25 million roof bolts are installed annually in the U.S. underground coal market with well over 1,500 operators involved in roof bolting on a day-to-day basis. Recently electrohydraulic roof bolting rigs have been installed to offer partial automation of the drilling cycle and the bolting cycle. The next stage is to provide a storage and loading system to allow full automation of fullcolumn resin roof bolts. This paper reviews the latest electrohydraulic roof bolting equipment and discusses the testing of a fully automated drill rig. Full electronic control allows each step of the roof bolting process to be recorded, providing a digital record of each installation, including hole depth, spin time, gel time, torque, and cycle time. Other benefits include monitoring of water pressure and flow, used to prevent blocked drill steels as well as digital fault finding. A fully automated roof bolting machine greatly improves operator safety and gives high-quality repeatable roof bolting with reduced cycle times.

Jul 1, 2023

By C. B. Henderson

The development of slurries of coal and water as a boiler fuel replacing No. 6 fuel oil has been actively pursued at the Atlantic Research Corporation since 1976. Funding for this effort has been provided by the U.S. Department of Energy, the Electric Power Research Institute, and by corporate funds. The name ARC-COALTM has been selected for these slurries. Stable coal-water slurries with bone-dry coal loadings between 62% and 77% have been prepared, evaluated rheologically, and successfully burned in an experimental furnace without the assistance of other fuels. The advantages and properties of these slurries, including combustion results, are reviewed. Also discussed is the pilot line used for processing barrel quantities of fuel and a pilot plant capable of processing 600 bbl/day, currently being designed.

Jan 1, 1982

By Gregory M. Rumbaugh, Todd R. Kostecki, Christopher Mark

From 2015 to 2021, five massive pillar collapses occurred at four underground stone mines in the eastern USA. These events resulted in powerful airblasts that damaged mine infrastructure and mobile equipment, seriously injured miners, and disrupted underground travelways. Each of these pillar collapses propagated through the overlying strata, causing a subsidence sinkhole on the surface. Pillar collapses are particularly hazardous for miners because they can occur with little warning and can affect miners that are far from the pillar collapse area. The following case studies show that certain factors may increase the likelihood of a pillar collapse. For instance, each of the 5 events involved at least 12 benched pillars with width-to-height ratios (w/h) of 0.8 or less. This study elaborates on these factors and proposes a framework to assist mine operators where they identify similar hazards.

Jul 24, 2023

By Thomas A. Mekelburg

Due to a tight ash constraint on the clean coal product and difficult middlings washability characteristics, a considerable amount of coal was being lost in the jig middlings at the Monterey No. 2 Mine. An investigation was conducted into circuitry to recover this lost coal with minimal effect on the total clean coal ash. A reverse two-stage hydrocyclone system cleaning at low specific gravities was selected. This system is currently recovering approximately 5.8 kg/s (23 tph) of 11.5% to 12.5% ash coal. The specific gravity of separation for the system is about 1.5 and the probable error is 0.13.

Jan 1, 1984

By VIVEK KUMAR HIMANSHU, M. P. Roy, P. K. Singh, A. K. Mishra, RAVI SHANKAR

Blasting with the aim to reduce oversize boulders in underground has many hurdles due to limited accessibilities and poor site conditions. Optimized drilling and blasting parameters can help to achieve this objective. The major challenges of the blast designers lie within deciding blast geometry, namely drill hole diameter, burden, and spacing. The general approaches covered worldwide to determine burden-spacing are based on various rules of thumb, which are based on previous experiences of blasts and the associated outcomes. However, many parameters influencing optimum burden-spacing to achieve desired fragment size are site specific. Sometimes drill geometry is decided based on associated blasting hazards rather than rock fragmentation. The Kuz–Ram model is a worldwide accepted rock fragmentation predictor. The parameters associated with this predictor also include burden-spacing for a blast. Back calculation of burden-spacing from the Kuz–Ram model can be used to achieve desired fragment size. This paper deals with burden-spacing determination by using an empirical approach for the underground stope ring blasting.

Jan 4, 2020

By Rennie B. Kaunda, Robert J. Sterrett

Some people in the mining-engineering field mistakenly believe that mine-water management primarily revolves around the treatment of mine waters that fail to meet applicable water-quality standards. While water-quality control is undoubtedly important, it represents only a fraction of what constitutes comprehensive site-wide, minewater management. A more holistic perspective recognizes that it also involves mine dewatering to maintain safe and workable conditions, securing sufficient water supply for operations, strategically handling surface water within and surrounding the openpit to prevent issues like flooding, developing robust post-closure plans to mitigate long-term environmental effects, and proactively minimizing any adverse impacts on local communities and ecosystems. This article provides a brief overview of topics that fall within the concepts of mine-water management. The focus is on openpit mines, as they are generally larger than underground mines. The management of mine water is highly dependent on local and regional climate such as tropical, desert or temperate climate. Each climatic setting has its own unique challenges, but there are also commonalities.

Jun 1, 2025

Asgco’s design of the Arrowhead Ceramic Lagging provides solutions to problems experienced with conveyor belt slippage around the drive pulley and severe wear problems on snub and bend pulleys. Asgco has developed a range of pulley lagging from ceramic, drive rubber and non-drive rubber lagging that is available in abrasion-resistant SBR and MSHA grade rubber for conveyor pulleys from slow belts all the way through to high-speed, high load belts. There is a growing need for a maintenance-free and reliable pulley lagging to ensure conveyor belts run to their highest efficiency.

Jan 1, 2006

By Harland E. Cofer

A computer-assisted resources and sedimentological study of the Andersonville, Georgia kaolin-bauxite district was begun in 1975 under a grant from the Office of Mineral Resources of the U.S. Geological Survey (Grant # 14-08-1110-G-173). A preliminary report on the kaolin and bauxite resources of the district has been placed on open file at the U.S.G.S. in Reston, Virginia; the Georgia-Geological Survey in Atlanta, Georgia; and Georgia Southwestern College in Americus, Georgia. In addition to a resources estimate, the objectives include the determination of the mineralogical variation, sedimentological parameters, and paleogeographic patterns of the deposition of the high alumina materials and their associated sediments. In the process of compiling data for the resources estimate, isopach maps were developed that provide information as to the shape, size, and distribution of the kaolin deposits and the kaolinitic sediments that contain them. These or similar maps developed for other districts can be useful exploration tools.

Jan 1, 1977

By William Gleason

Despite a global slowdown in most mining sectors, Caterpillar, the world?s largest mining equipment maker continues to forge ahead with new, and improved offerings to the global mining industry. On Nov. 10, as part of its Loading and Hauling Mining Focus Session at its Tinaja Hills proving grounds south of Tucson, AZ, Caterpillar unveiled to customers and media its two latest mining products, the 994K wheel loader and 6020B hydraulic shovel. The Caterpillar 994K wheel loader builds on a nearly 25-year history of the 994 model but with one noticeable difference ? the 994K is bigger ? much bigger. Weighing in at 239,142 kg (527,218 lb) the 994 K is up to 20 percent larger and comes with up to 30 percent increase in payload capacity. This behemoth of a machine is currently being tested at Caterpillar?s Tucson Proving Grounds, Anglo Gold Ashanti?s Cripple Creek and Victor gold mine in Colorado and Taseko?s Gibraltor copper and molybdenum mine in British Columbia, Canada.

By N. Agron-Olshina

The application of the QEM*SEM image acquisition and analysis system to the measurement of the mineral matter in coal and the materials in fly ash is described. A new sample mounting technique was developed using iodinated epoxy to provide a backscattered electron contrast between the coal, the mounting medium and the mineral matter. Several comprehensive and detailed species identification programs for silicate minerals and materials were developed to analyse the 1000 count x-ray spectra used for the measurements. Case studies are presented to demonstrate the capabilities of the new technique to distinguish different coals and fly ashes by their mineral and material composition rather than by conventional chemical analysis. Applications of the new technique are aimed at demonstrating that composition and size distributions obtained from OEM*SEM measurements can be used: 1. to characterize coal with respect to combustion problems in power stations, 2. to characterize coal for fine coal cleaning, 3. to characterize fly ashes in relation to problems such as erosion in combustion systems and the ease of precipitability in dust collection facilities, 4. to refine the classification systems used in marketing coal for pulverized fuel firing and fly ashes as a component of cement and building materials.

Jan 1, 1992

By David Kwietnewski

Roadheaders are gaining widespread acceptance in North America as a means for mechanical tunnel excavation. Until recently, almost all of the large-scale North American tunnel projects were excavated one of two ways ? the tried and true drill-and-blast method or with the use of tunnel boring machines (TBM), the hi-tech super-excavators. TBMs enjoyed fast-growing popularity worldwide as TBM manufacturers offered greater technology to meet the demand of the civil tunnel industry in the late 20th century. Recently, though, more tunnel projects, large and small, can thank the brute force of a roadheader for getting the job done.

Jan 1, 2011

By Gordon Clark, Basar Arioglu, Nasri Munfah, Sanja Zlatanic, Tolga Togan

"The 13.2 m (43 ft) external diameter, double deck Istanbul Strait Road Tube Crossing is one of the most challenging underwater tunnel projects in the world. Subjected to 11 bars of hydrostatic pressure, variable geology, and being in a very active seismic area, the execution of the project required innovative solutions, sophisticated construction techniques and prudent risk management approach. The 5 km (3.1 mile) tunnel consists of a 3.4-km (2.2-mile) tunnel boring machine- (TBM) bored tunnel, 1 km (0.62 mile) twin NATM tunnels and cut-and-cover sections. The project is being delivered in a build-operate-transfer (BOT) contract in a public-private partnership. The technical challenges, coupled with financial and commercial risks required the implementation of sophisticated risk management tactics including the provision of independent design verification. The project was opened to traffic on December 20, 2016, four months ahead of schedule.. This article presents the technical challenges of the project from the design, construction, and risk management aspects..Project backgroundThe $1.245 billion Istanbul Strait Road Tunnel Crossing project, dubbed the Eurasia Tunnel, is one of several major infrastructure projects being implemented in the Republic of Turkey in a public-private partnership approach. The project provides a direct and easy connection between the Anatolian (Asian) side of Istanbul and the heart of its historical district on the European side across the Bosphorus Strait which connects the Black Sea with the Sea of Marmara. The project improves connections to a wide network of motorways on both sides, increase capacity across the Bosphorus by 100,000 vehicles a day, reduces congestion and saves motorists an average of 45 minutes of commuting time in each direction bringing significant economic benefits to the city and the region. It eases traffic across the strait, reduces congestion, decreases pollutants and emission while maintaining Bosphorus. It is the most complex part of the project with the greatest challenges and risks. Part 2 is 5.4 km (3.6 miles) long consisting of 3.4 km (2.2 miles) of 13.2 m ( 43.3 ft) external diameter TBM bored tunnel under the Bosphorus Strait, 1-km (0.62-miles) of twin NATM tunnels on the Asian side, cut-and-cover transition boxes in the Asian and the European sides and depressed approaches on both sides. In addition, this segment includes the toll plazas, ventilation buildings, and the tunnel control and maintenance facilities."

Mar 1, 2017

By Gary L. Mowrey

Visible and sometimes audible indications of excessive underground rock pressure such as pillar fracturing, squeezes on chocks, and "roof talk" are familiar to mining engineers. Such signs often precede rock failure on a larger scale and therefore may be used as a warning. Nevertheless, these subjective observations do not provide an adequate means of evaluating the existing rock pressure conditions in a mine. One method which appears to be extremely promising in determining the stability of geologic structures in general is that of monitoring their associated micro seismic activity. Mining engineers generally agree that during the process of rock deformation and failure small-scale seismic ("microseismic") vibrations are produced in the rock itself. These transient vibrations propagate through the rock structure and may be detected at a considerable distance from the failed rock by employing suitable electronic monitoring equipment. Hardy (1) has presented a detailed review of microseismic research in the mining, petroleum, and geoscience areas, and it is apparent that relatively little application of micro seismic techniques have been made in coal mines. This is especially true in North America since here most coal mines are fairly shallow and consequently are not generally subjected to excessive stresses. Furthermore, strict Federal and State mining laws limit the use of electrical equipment in coal mines complicating the use of the necessary monitoring facilities. In terms of both mine safety and economics, monitoring microseismic activity appears to be invaluable in the detection and location of over-stressed pillars and unstable roof conditions caused by development and production work. In 1970 The Pennsylvania State University Rock Mechanics Laboratory became involved in a research project, sponsored by the U.S. Bureau of Mines, to investigate the feasibility of using microseismic techniques to detect and to locate potential regions of instability around a longwall coal-mine operation [Hardy and t10wrey (2); Mowrey (3)]. In this study geophones (velocity gages) located in an array of shallow boreholes drilled from the surface above the active area of the longwall were employed to detect microseismic activity, and a mobile micro-seismic monitoring facility was used to condition and record this data for later analysis. This project is unique in that measurements were made from near-surface geophones rather than geophones installed on the mine itself. Two advantages are apparent, namely that (1) there are no electrical limitations on the monitoring system and that (2) mining operations can continue normally because there is no monitoring equipment or cables in the mine.

Jan 1, 1978

By Ben Roderds

The Waneta Expansion Project (WAX) is located near the existing Waneta Dam site at the confluence of the Pend d?Oreille and Columbia rivers, approximately 10 km (6.2 miles) south of Trail, BC, Canada. The WAX owners consist of a partnership between Fortis Inc., Columbia Basin Trust and the Columbia Power Corp. This design-build project was awarded to SNC-Lavalin in late 2010 and is expected to be operational in mid-2015. The WAX consists of a new 335-MW powerhouse, including two new Francis turbine units, each generating approximately 167 MW. The powerhouse is located downstream of the existing Waneta Dam, and will make use of excess water that would otherwise be spilled during the runoff season. Water will be funneled to the turbines through an intake structure and two 10.5- m (34.5-ft) diameter, concrete-lined Penstock Tunnels. A 10-km (6.2-mile) transmission line will connect the powerhouse to existing electrical grids. Redpath/FKCI Waneta Tunnelers (RFK) was subcontracted by the heavy civil contractor, the Aecon/SNC Lavalin (ASL) joint venture, to excavate the two penstock tunnels and install the cast-in-place concrete liner. RFK is a joint venture partnership between J.S. Redpath Ltd., an underground mine contractor located in North Bay, Ontario, and Frontier-Kemper Constructors ULC, a heavy civil tunneling contractor based in Nova Scotia, Canada. Since penstock tunnel excavation was planned using drill-and-blast methods with a significant grade of more than 17 percent, the combined experience of these two contractors was a perfect match.

Mar 1, 2014

By L. Yuan, A. C. Smith

MFIRE, the mine-fire simulation program of the U.S. National Institute for Occupational Safety and Health (NIOSH), is widely accepted as a standard for assessing and predicting the impact of a fire on the mine ventilation system and the spread of fire contaminants in coal and metal/nonmetal mines. MFIRE has been used by U.S. and international companies to simulate fires for planning and response purposes. It is a dynamic, transient-state, mine ventilation network simulation program that performs normal planning calculations. It can also be used to analyze ventilation networks under thermal and mechanical influence, such as changes in ventilation parameters; external influences, such as changes in temperature; and internal influences, such as a fire. The program output can be used to analyze the effects of these influences on the ventilation system. Since its original development by Michigan Technological University for the former U.S. Bureau of Mines in the 1970s, several updates have been released. In 2012, NIOSH completed a major redesign and restructuring of the program with the release of MFIRE 3.0. MFIRE’s outdated Fortran programming language was replaced with an object-oriented C++ language and packaged into a dynamic-link library. However, the MFIRE 3.0 release included no change or improvement to the fire-modeling algorithms inherited from its previous version, MFIRE 2.20. This paper reports on improvements that have been made to the fire-modeling capabilities of MFIRE 3.0 since its release. These improvements include the addition of the t-squared fire as a new fire-source model and the ability to include available heat-release-rate versus time data, the addition of a moving fire source for conveyor-belt fire simulations, improvement of the fire location algorithm, and the identification and prediction of smoke-rollback phenomena. All of the improvements discussed in this paper will be included in MFIRE 3.1 and released by NIOSH in the near future.

Jun 1, 2016

By Hugh W. Evans

Many reports and papers have been delivered on projects under construction or already in operation, but we believe there are few that have been written about projects yet to be built specifically dealing with advanced mine and environmental planning. This paper describes such planning for Atlantic Richfield Company's Black Thunder mine. Project planning is a cyclic phenomenom involving four broadly overlapping planning steps (Figure 1). The demands of the public include needs that can be satisfied through planned resource development. Using a base of information that partly exists and must in part be gathered and updated, the preplanned development can be, evaluated. The evaluation process, with built-in environmental constraints leads to an implementation procedure. Implementation results in the development, including the release of the affected area to other public demands that follow.

Jan 1, 1975