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By A. Eftimie, M. Stanley

The World Bank Group (WBG) believes that extractive industries can make significant contribution to sustainable development and poverty reduction, providing that environmental, social, and corporate governance issues are properly managed. The WBG recognizes that stakeholders have legitimate concerns about the impact of extractive industries, and management proposals are built around the central theme that investments and policy advice in the extractive industries should lead to poverty reduction. To help governments create appropriate policy and regulatory frameworks, this paper focuses on the linkages between overarching policies and laws and the management / governance of extractive industries at the local communities. It encourages the use of new instruments designed to help ensure that local communities benefit from extractive industries.

Jan 1, 2005

By S. Jayson Ripke, Shane Hoff

Cleveland-Cliffs’ Northshore Mining Company operates a magnetic iron ore (taconite) concentrator and pelletizer in Silver Bay, MN. These are two recent cost reduction projects: 1. Rougher Magnetic Separators were upgraded throughout the concentrator; throughput and recovery were simultaneously improved. 2. Green Ball Roll Screens on one agglomeration circuit were upgraded from 3.5-inch to 2.5-inch rolls. Throughput improved by 24% from 62 to 77 LTPH. Green ball size distribution improved as an added benefit.

Jan 1, 2005

By L. Yuan, J. H. Rowland, R. A. Thomas, D. Bahrami

Blasting is the main method of production in many non-coal underground mining operations and produces multiple toxic gases as a result. The Mine Safety and Health Administration (MSHA) requires mine operators to measure the level of toxic gases in mines as frequently as necessary to ensure they are below regulatory safety limits. The current practice uses portable gas monitors to check the concentrations of toxic gases after a fixed post-blast time. This paper studies the application of a gas monitoring system in the return entry of a limestone mine to determine a safe re-entry time. The National Institute for Occupational Safety and Health (NIOSH) conducted such a monitoring program in a limestone mine from September 2016 through May 2018. NIOSH/PMRD (Pittsburgh Mining Research Division) is endeavoring to develop workplace solutions to improve detection of and reduce the risk of hazardous conditions. This study showed that the use of gas monitoring in the return air can be a useful tool at the mine operator’s disposal to detect and reduce the risk of hazardous conditions and also to reliably estimate the re-entry time. INTRODUCTION Underground miners are at risk of overexposure to toxic gases from various sources. Production blasting operations using explosives in underground mines are a source of multiple toxic gases that could be harmful and even fatal to humans if prolonged exposure occurs beyond the safe limits. According to Code of Federal Regulations, Title 30, Part 57.5002 [1], metal and nonmetal mine operators must conduct gas, mist, and fume measurements as frequently as necessary to determine the adequacy of control measures to protect miners from overexposure to harmful gases. MSHA will inspect mine operators’ activities to verify the evidence of such measurements [2,3]. Continuous gas monitoring in the return air is an effective way to make sure that toxic gas concentrations at the working areas are kept below the regulatory limits before the return of miners. Toxic gases can enter the mine atmosphere from different operations, such as welding, combustion, and blasting. The main gases produced from blasting are carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), and nitrogen dioxide (NO2). Other gases are produced in small amounts and, therefore, were not considered for this study. Related regulatory and recommended exposure limits of CO, NO, and NO2 gases are summarized in Table 1 [4].

Jan 1, 2019

By E. C. Westman, F. J. Shreve

This paper presents the design and construction of a multi-channel geophone array that improves tomographic imaging capabilities in both surface and underground mines. Especially important in the design of the array is sensor placement. Three issues related to sensor placement are addressed in this paper: 1) sensor placement in long, horizontal boreholes, 2) development of simple, robust, MSHA-acceptable clamping unit, and 3) orientation of the geophones within the borehole. Improved imaging capabilities will produce energy, environmental, and economic benefits by increasing exploration accuracy and reducing operating costs.

Jan 1, 2002

By K. V. S. Sastry, K. D. Lofftus

Mathematical modeling and computer simulation are two valuable quantitative tools that are being effectively applied to mineral process- systems. This paper presents an up-to-date assessment of process modeling and simulation, identifies a number of associated challenges and opportunities and discusses in detail sane of the aspects of applying the current state-the art modeling and computational tools.

Jan 1, 1989

By H. Arima, T. Fujita, W. Yen

The copper catalyzed gold oxidation and reduction mechanisms in ammonium thiosulfate solution were investigated by Eh-pH diagram based on the optimum reagent combination for 60 mass% -75 µm silicate ore at 16g/t Au with the maximum gold extraction of 92% and the minimum ammonium thiosulfate consumption of 23 kg/t-ore for 24 hour’s leaching at ambient temperature. The gold recovery by cementation was nearly 100% by Zn and Al powders at Metal/Au mass ratio of 30, and around 95% by Cu powder at Cu/Au+ mass ratio of 50. In order to oxidize the gold efficiently with the less thiosulfate consumption, the stable region of [Cu(NH3)4]2+ should be as wide as possible in the region, where [Cu(S2O3)2]3- was more stable than [Cu(NH3)2]+. In order to reduce gold from the pregnant solution with the less metal powder’s (Zn, Cu, Al) consumption, the stable region of [Cu(S2O3)2]3- should be wider than [Cu(NH3)2]+ on copper precipitation. Zinc powder may recover gold more efficiently than copper powder with the similar trend on the effect of ammonia, copper and thiosulfate. However, the large amount of copper will be co-precipitated along with gold since the stability of zinc ammine and thiosulfate complexes are higher than that of copper’s. Aluminium may reduce gold efficiently at higher thiosulfate concentration and pH. These results were confirmed and compared with the optimum reagent combination for finer grind sample at 100 mass% -75 µm, which is the optimum ore size for the standard cyanidation at 1.0 g/ l NaCN to obtain about 95% gold extraction. The optimum reagent combination was concluded as 0.5 mol/l NH4OH, 0.0001 mol/l CuSO4*5H2O and 0.05 mol/l (NH4)2S2O3 with the result of 94% gold extraction and 3kg/t-ore of ammonium thiosulfate consumption. Gold and copper stabilities were well agreed with the result of coarser grind ore thermodynamically. The lower reagent combination will reduce gold oxidation power, but significantly minimize the reagent consumption. From this pregnant solution, nearly 100% of gold was successfully recovered by zinc precipitation at Zn/Au+ mass ratio of 30. Aluminium and copper precipitations resulted in less than 40% of gold recovery at Metal/Gold mass ratio of 30. The reagent consumption cost on this lower reagent combination followed by zinc precipitation was $1.6/t-ore, while the cyanidation was $3.1/t-ore. Thiosulfate oxidation mechanism indicated the similarity to Belousov-Zhabotinsky reaction.

Jan 1, 2002

By S. J. Benson

The Harts Range deposit, owned by Olympia Resources is located some 130 kms northeast of Alice Springs, in central Australia (part of Australia’s Northern Territory). The core economic minerals here are industrial grade garnet and alumino magnesio hornblende (AMH). The resource contains an estimated 2.3 million tonnes of recoverable garnet and 6.2 million tonnes of recoverable AMH, making Harts Range one of the most significant abrasive medium deposits in the world. Part of the general marketing axiom of Olympia Resources is to make high quality products from the garnet and also a special series of blended garnet/AMH products to match the needs for other sectors of industry. The deposit mineralization is of alluvial origin and thus, requires no significant liberation regimes. Over 50% of the head feed is in the form of SiO2/quartz and as much as 17% is –63micron clay slimes and mica. Original pilot scale testwork for flowsheet development centred around fairly conventional wet gravity systems, with spiral concentrators being the pre-eminent separating device. To a point, this type of flowsheet was going to achieve some of the aims albeit fairly predictably. The one area that this circuit would be very limited though is in the recovery of the very coarsest of the medium SG minerals. This was going to be a very important and longer-term costly flaw. Amongst the highest demand, greatest value of products to be produced will be the range of garnet & AMH in the +600 microns sector. A flowsheet dominated by spirals would be fated to forfeit a significant proportion of these coarse minerals to tails. At the Outokumpu Technology P/L test facilities in Perth, testwork was conducted using a pilot scale Floatex® Density Separator, the LPF-230 model. Using a twin stage approach, whereby a primary Floatex® underflow reports directly to a secondary Floatex®, recovery of the economically important +600 micron garnet was increased from 65% in the spirals-only flowsheet to 95% using the Floatex® based flowsheet. Finally, the other significant aspect of this approach is in substantial simplification of the circuit required and a huge reduction in plant footprint. Also, the nature of using hindered settling provides substantial opportunities for process control and automation.

Jan 1, 2005

By Gregory D. Savage, Bruce M. Everett

Introduction The growing role of Colombia as a major supplier of internationally traded steam coal has been widely discussed in the industry. Although Colombian coal has been produced and exported in small quantities for a number of years, the country's position as a major coal exporter began in earnest in 1985 with the first commercial exports from the Cerrejon North Block Project. The mine is located on the Guajira peninsula in northeast Colombia, about 145 km (90 miles) from the coast (Fig. 1). In addition to the mine itself, the project involves construction of a dedicated railroad and port. This forms a modern, efficient, and integrated system. The project is embodied in a 50-50 association contract between International Colombia Resources (Intercor), a wholly-owned subsidiary of Exxon, and Carbocol, the Colombian state coal company. Intercor and Carbocol share investment and operating expenses equally. Intercor has the additional responsibility of managing operations on behalf of the partners. Each partner is entitled to 50% of the coal produced, and each markets its share separately. The project is a multi-seam, truck and shovel operation, based on large reserves (2 to 3 Gt or 2.2 to 3.3 billion st) of high quality bituminous coal. Exports began in the first quarter of 1985, at modest levels through what is called Early Coal Facilities. The permanent coal handling system began operation in February 1986. Production will increase rapidly in each of the next few years, reaching the design capacity of 15 Mt/a (16.5 million stpy) in 1989. Based on available resources, however, the resource will support expansion, and continued growth in production into the 1990s is feasible. Importance of transportation The success of a new coal export venture, such as Cerrejon, depends heavily on efficient transportation. In the international coal industry, overland and ocean transport can in some cases account for 40% to 50% of the final value of the product. Many coals, such as western US subbituminous coals, cannot reach export markets at all because of their low heat content and great distance from export markets. By the same token, low-grade resources are often commercially attractive for local markets even in the face of competition with much higher quality coals from distant sources. Figure 2 shows the growth in steam coal imports into Europe, the largest trading market. Through

Jan 6, 1986

By John L. Kaplin

The underground construction for the Phase I Combined Sewer Overflow(CSO) Project is on an impressive scale by any measure, appearing more so in a midsize city like Providence, RI. The Narragansett Bay Commission recently completed $350 mil-lion in construction to improve the water quality in Narragansett Bay. This project included a number of serious challenges, delays, and disputes. Looking back on this complex project completed within budget, it is hard to consider the work as anything other than a success. Along the way, this outcome did not always appear certain.

By Augustine O. Orumwense

Ball mills are commonly used for regrinding operations in the mineral processing industry. But, in recent times, efforts are being made at the introduction of stirred mills particularly for those instances where very fine grinding is required. Media type (steel shot, glass beads, alumina balls and crushed quartz), media size, mill speed and the number of passes required to obtained the target product size are studied. The product size and energy consumption are used in the evaluation of the test results. The grinding media size, shape, density, filling ratio, mill circumferential speed and grinding time play a distinct role in product size fineness.

Jan 1, 2005

By Stig Eriksson

In Switzerland two major railway systems as shown below in Figure 1 has recently been completed or is under construction: ¦Lötschberg, south of Bern which was commissioned in 2007 ¦Gotthard, south of Zurich which is scheduled to be commissioned in 2016The aim is to increase the transport capacity of the railway system and to transfer more transport of goods to the railway by offering transport of trailers and lorries on the new railway systems. It will have a positive environmental impact but also improve the congested traffic situation of the highways in north-south directionThe Gotthard tunnel is totally 57 km (35 mile) long and the Lötschberg tunnel is 35 km (22 mile) long. Both tunnel systems consist of two parallel single track tunnels connected with cross tunnels at every 333 m (1 093 ft). Additionally there are cross-over tunnels and caverns for installations and operation. In the Lötschberg tunnel, the majority of the excavation has been by Drill & Blast and in Gotthard tunnel the major part is being excavated by TBM.

By Felicity Lloyd, Stuart Kearns, Roger McLimans

The metamorphic terrane of southwestern India is a geological environment containing ilmenite source-rocks, transport drainage systems, and resultant beach sand deposits that contain altered ilmenites greater than 60wt% TiO2. As such, this environment provides a geological laboratory, from source to deposit, for the investigation of ilmenite origin, alteration, and geochemical character. Ilmenite samples from potential source rocks, river sands, and beach sands all show degrees of alteration and a variety of alteration textures (iron leaching) producing leucoxene (here defined as >70 <90wt% TiO2) and progressing to rutile (here defined as >90wt% TiO2). Distinct alteration textures are specific to different source rocks and are used together with trace element geochemistry as provenance criteria. Ilmenites are classified on the basis of their trace element content. In India, the ilmenites are classified principally according to the Mg, Nb, and Mn content and this signature defines potential source rocks, even where the ilmenite is altered to a TiO2 content of 70wt%. The trace element data may fingerprint source rocks whose ilmenite is more prone to iron leaching and that criterion has application in exploration for higher-grade ilmenites.

Jan 1, 2005

By R. Strandahl

As one of the largest private utilities globally, E.ON currently operates hard coal fired power stations in with a total installed capacity of some 20.000 MW: These thermal power plants consume domestic coals but are increasingly dependent on imported seaborne traded coal (in 2009 approx. 17 million t). Knowing that the company’s reputation and credibility depends in part on how E.ON lives up to the responsibilities along the entire energy value chain, E.ON takes a collaborative approach with the various suppliers. Hence, E.ON’s responsible policy also applies to the procurement of coal; the utility launched in 2009 a comprehensive Corporate Responsibility program with special focus on supply-chain audits. One of the first coal audits focussed on the Cerrejón coal mine in North Eastern Colombia. The authors will share the key learning’s and experience from the Colombian audit jointly conducted with an independent auditor and E.ON experts from the Corporate CR and E.ON Energy Trading.

Jan 1, 2011

By M. J. van der Meulen

"The Netherlands has major resources of sand, gravel and clay, exploited mainly for construction works and the building materials industry. As in most western countries, mineral extraction meets with considerable societal resistance. To this end, Dutch minerals policy aims to prevent extraction by promoting economical use of materials, and the use of alternative (secondary or renewable) materials. Up till recently, it also included a system of production planning to sustain supplies of regionally scarce materials. Dutch policy development is reviewed and discussed in terms of pitfalls and possibilities for mineral planning in general. Promoting secondary substitution has been quite successful, and presents an example. In contrast, the production planning system has been controversial from the start and ineffective as a result, mainly because it attempted to solve supply problems without properly addressing the underlying resistance. For this reason the system is in the process of being abandoned. The full paper will be published in: Petterson, M., McEvoy F, & Marker, B.R. (Eds) 2005, Sustainable minerals operations in the developing world, Geol. Soc. Lond. Special report series, in press. This abstract is reprinted with kind permission of the publisher."

Jan 1, 2005

By R. Owen, T. Canty, C. Marks

The industrial vision system provides on-line 2D particle size analysis for aggregate slurries in both the overflow and underflow of hydrocyclones. This paper covers required vision system features allowing CCD cameras to function in the harsh environment of a mine milling area. The study conducted demonstrates the system’s capacity to obtain particle size distributions for controlling hydrocyclonic separators. The particle size distribution is obtained within seconds and immediately updated to allow for process adjustments. Results are then provided as a graphical computer generated display or output as a 4-20mA current loop for process control. The primary use of the vision system is in classifying particles in cyclone overflows which are often a few microns in size. Typical size information for actual mine slurry samples are presented and possible control schemes discussed.

Jan 1, 2002

By J. L. Carr

Every year, severe injuries and fatalities occur when a miner is struck or pinned by a continuous mining machine, shuttle car, scoop or other piece of mobile mining equipment. Proximity detection systems offer a means to prevent these types of injuries and fatalities by sensing the presence of a miner and disabling machine motion. Although hundreds of these systems are installed and in use in operating coal mines, the influence that coal has on the electromagnetic fields associated with these systems has never been rigorously quantified. NIOSH researchers have conducted tests to measure whether the proximity of coal has a significant influence on a popular design of proximity detection system. The system tested utilizes a low frequency magnetic field generator that would be mounted on the mining machine. At the NIOSH Safety Research Coal Mine in Pittsburgh, researchers measured the performance of a simplified proximity detection system of this type first on the surface then underground at varying distances from a coal face. Analysis of these measurements shows that the presence of coal does not have a measurable impact. Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health.

Feb 27, 2013

By William W. Edgerton

The California Department of Transportation (Caltrans), the Contra Costa Transportation Authority (CCTA), and the Alameda County Congestion Management Agency (Alameda CMA) are involved in a unique partnership on the planning and design of the fourth bore of the Caldecott Tunnel, located on State Route 24 in Alameda and Contra Costa counties. The project will add a two-lane bore north of the existing three bores. The project will alleviate traffic congestion in the non-peak direction. This paper provides background on the existing facility, summarizes the need for the new fourth bore, describes the proposed improvements, sets forth the approach for project delivery, and lists some of the challenges that are expected during construction.

Jan 1, 2008

By R. G. McLusky

This paper analyzes the opinion in Bragg v. Robertson, 72 F.Supp. 2d 642 (S.D. W.Va. 1999), a case which threatens the future of surface mining in West Virginia and which will almost certainly result in new policies or rules that will affect surface mining everywhere. This paper addresses: (1) the jurisdictional bases of the action which relies on the federal surface mining laws to enforce a state mining program; (2) settlement agreements reached in the case that threaten to alter federal policies beyond West Virginia borders; (3) a programmatic environmental impact statement on mountaintop mining being undertaken by the federal government; and (4) an opinion by the Court outlawing excess spoil disposal in intermittent and perennial streams.

Jan 1, 2001

By P. J. Doig

The LCLS project at SLAC will allow new insights into material properties, chemical reactions and biological processes. The project includes half a mile of new underground construction. Excavation in weathered rock is by NATM, using AM 50 roadheaders. Construction began in 2006 and is expected to be completed in 2008. This paper details the construction of the tunnels and cavern on the project.

Jan 1, 2008

By Rex E. Loesby

The dramatic increase in molybdenum prices from the low of less than $2.50/lb in 1999 to more than $40/lb in 2005 has caught the attention of molybdenum mine owners and exploration project developers. Between 2005 and early 2007, prices pulled back and stabilized within a trading range of $25/lb to $30/lb. This 1,000 percent price increase has motivated most existing producers to expand production and is motivating those with molybdenum prospects to accelerate the development process for earliest possible production. It is still unknown how much new production will come from existing mines, how much production will be needed from new mines if demand continues to grow and how many potential new mines might be available to meet future demand. And of course, the billion dollar question is whether molybdenum prices will remain high, or will they fall back to the low levels seen during the 1980s and 1990s? This article attempts to answer these questions in a way that will help molybdenum project developers and financiers plan for the future.

Jan 1, 2007