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By Jean Habimana

The Detroit Upper Rouge Tunnel CSO Control Project will capture and store up to 201 MG of combined sewer overflow from 28 outfalls in Detroit, Dearborn Heights and Redford Township during wet-weather events. The history of rock tunneling in the area is associated with high groundwater inflows, artesian pressure, and hazardous and combustible gases. This paper presents the geotechnical considerations for designing the 11.28-km (7-mile) long, 9.14 m (30-ft) finished diameter tunnel and its associated adits, chambers and shafts, including the discussions of geotechnical investigations, rock mass characterization, estimated groundwater infiltration during construction, and the selections of excavation methods and lining system based on anticipated ground behavior to be encountered.

Jan 1, 2008

By F. M. Doyle

Ion flotation shows great promise for recovering and removing metal ions from dilute process streams, either for environmental compliance or to recover values. This technique uses an ionic collector to concentrate non-surface active colligend ions of the opposite charge from a bulk solution at the solution?vapor interface. With a sufficiently large solution?vapor interfacial area (provided, for example, by sparging gas through the solution), the colligend can be concentrated and removed along with the collector in a foam phase. A key limitation on using the technique in the minerals industry, where many process streams contain a variety of ions and have relatively high ionic strengths, is the need to control which ions are interacting with the collector. Here the effect of three different chelating agents, namely dodecyldiethylenetriamine (Ddien), ethylene diamine tetraacetic acid (EDTA) and triethylenetetraamine (Trien), on the selectivity of copper, nickel and cobalt, or copper and alkaline earth metal ions, is reported. The results are discussed in terms of their implications for adoption in the minerals industry.

Jan 1, 2009

By J. D. Potts

Installation of a horizontal air blocking shelf around the inside perimeter of the surface mining drill deck shroud is proposed to improve dust capture. Without the use of this shelf, a strong coanda effect airflow pattern results in dust leakage to the environment, especially at the shroud-to-ground interface. Bailing air exits the drill hole and travels along the drill steel to the underside of the table, where it fans out across the bottom of the drill table and continues down the sides of the shroud. This dust-laden bailing air then strikes the ground and fans out under gaps between the shroud and the ground. The proposed shelf prevents dust-laden air from striking the ground by redirecting it toward the center of the enclosure, where it can be captured. Laboratory tests demonstrated that the shelf reduced dust levels outside of the shroud by 81% under operating conditions consisting of a 1.9:1 collector to bailing airflow ratio, and a 5.1-cm (2-in) gap between the shroud and ground. The shelf was 15.2-cm (6-in) wide and located at a height equal to 2/3 the distance measured from the bottom of the shroud to the bottom of the drill table. The air blocking shelf was also capable of overcoming the adverse impact of vertical leakage along the shroud seams as long as this leakage was confined to an area below the horizontal plane defined by the shelf location.

Jan 1, 2009

The trend for using larger equipment in open pit mining to achieve cost effectiveness raises the question about the optimum economic point of scale in the current world of globalization. The present paper treats this question through the prism of a new methodology of assessing the impact of the size of production equipment on the economic outcomes of coal mining ventures. The methodology incorporates a production scheduling optimization model that implements both principles of mine planning, coal quality optimization and waste deferment. The implementation of the waste deferment principle dealing with the spatial and time aspects of the mine sequence arrangement allows the adequate modeling of the optimality of production equipment scale through the use of mine investment parameters, such as, purchase and ownership costs and discounted cash flows analysis. A case study is provided to illustrate the applicability of the new methodology.

Jan 1, 2004

In recent years, Computational Fluid Dynamics, CFD, has been commonly utilized in the mining industry to model the fluid flow behavior in underground mine workings. This paper uses CFD modeling to simulate the airflow behavior in underground crosscut regions, where brattice sails are used to direct the airflow into these regions. Brattice sails are cost effective ventilation control devices for temporary or permanent use in underground mining. They can be used to deflect air into the unventilated areas such as crosscut regions. Their design and installation is a fundamental issue for maintaining a sufficient supply of fresh air and achieving effective air circulation and contaminant removal. At the same time, they should have little impact on the mine ventilation system. This paper presents the results of a two-dimensional CFD model, which examines the effects of brattice length on fluid flow behavior in the crosscut regions. The results of this study will assist in understanding the ventilation air behavior and in determining the optimum size of brattice curtain (sails), which provide a highly effective contaminant removal from the unventilated mine areas. This, in turn, helps the mine ventilation designers to meet the mine safety requirements.

Jan 1, 2009

The MINER Act of 2006 mandated that all underground coal mines must install and maintain refuge chambers. Refuge chambers serve as a temporary shelter in case of emergency. Several factors affect the performance of a refuge chamber: heat production inside the chamber and introduction of CO when chamber doors are opened are two major factors. This study examines the CO purging process and to determine total air quantity and time necessary to lower the CO con-centration to safe levels for different inlet/outlet configurations using three-dimensional simulation technique. The study uses Reynolds Averaged Navier Stokes and continuity equations along with the spe-cies transport model assuming uniform air mixing. The heat transfer of any kind is neglected and the purging process is assumed to take place isothermally. The standard k-e model is utilized for simulating turbulence in the flow field. This research provides useful guidelines in developing an efficient strategy for purging refuge chamber. Keywords: Airlock chamber, Purging, Carbon monoxide, Turbulence

Feb 27, 2013

By Hemang Desai

A damaged outlet pipe beneath Lenihan Dam has restricted reservoir discharges, severely constraining the owner?s groundwater recharge program. The solution, a new outlet pipeline through the dam?s right abutment, includes an approximately12.2-m-deep (40-ft-deep) shaft and 618.7-m-long, 4.3-m-diameter (2,030-ft long, 14-ft-diameter) tunnel mined in Franciscan melange composed of hard blocks of rock and soft clayey matrix. Alternating road header with drill and blast operations and using steel ribs and shotcrete have proven a flexible combination for handling the variable ground conditions. Excavating the shaft and connecting it to the tunnel require lowering the reservoir for five months, during which time careful construction sequencing and use of a tunnel plug eliminate the risk of an uncontrolled discharge.

By C. Green, J. Uhrie, C. Filippone, A. Guzman

A central aspect of heap leach management and recovery optimization is solution control. Insofar as each heap is unique in physical and metallurgical properties, it is essential to understand the hydraulic parameters that control the migration of solution on a case-by-case basis. Water Management Consultants, as part of an ongoing research effort for Phelps Dodge Process Technology Center, have adapted techniques of parameter estimation for application to data typically resulting from metallurgical column testing. The parameterization is completed within the context of a variably saturated flow model that allows interpretation of available hydraulic information collected during hydrometallurgical column tests. A novel interpretation approach is introduced to extract the necessary hydrodynamic parameters from typical hydrometallurgical data sets. Results from the application of the approach to standard metallurgical test data will be presented together with a discussion of the application of information gained to the design and operation of a heap.

Jan 1, 2002

By J. F. Lupo

There are numerous mines throughout the world that have open pit highwalls developed partially or wholly in soil or soil-like materials. Soil-like materials are considered to include soils (either transported or residual) and highly weathered rock, which may have soil-like behavior. These materials generally have characteristics or material properties that vary considerably from those of moderately weathered or fresh rock. Given these differences, it is important to consider the characteristics of soil-like materials to design safe open pit slopes. In the design of open pit slopes in soil-like materials, it is important to recognize the behavior of these materials is strongly dependent upon their mineralogy, degree of weathering, cementation, stress history, depositional history, and presence of water. As a result, soil-like materials may contain one or more of the following characteristics that can have a significant effect slope stability and design: - Relict structural features (joints, faults, etc), - Sensitivity to moisture (both wetting and drying), - Zones of alteration with variable strength and drainage characteristics, - Zones of low permeability creating perched ground water conditions, and - Undrained and drained strain softening or strain hardening behavior.

Jan 1, 2011

By W. Z. Rogers

U.S. feldspar output sold or used in 2005 was an estimated 760 kt (838,000 st), valued at $44 million free-on-board plant. This was below the 2004 volume and was the second year of decline in a row. Output included flotation concentrates, feldspar content in feldspar-silica mixtures, potash feldspar and aplite. The strong housing market in the United States maintained demand for ceramic tiles, plumbing fixtures and fiberglass insulation requiring feldspar. Shipments of glass containers were about the same as in 2004. Imports of ceramic tiles and plumbing fixtures continued to increase, taking the place of U.S.-produced goods and the feldspar required to make them. For 2005, 80 percent of the ceramic tiles sold and 50 percent of the plumbing fixtures sold in the United States were imported. Since 2000, manufacturing plant closures in the plumbing fixtures industry have reduced the demand for feldspar and feldspar-silica mixtures by 100 kt (110,000 st). Increased demand from the ceramic tile industry has partially offset the lost volume.

Jan 1, 2006

By G. T. Adel, J. D. Miller, C. L. Lin

Washability analysis determines the maximum separation efficiency that can be achieved in the operation of coal preparation plants. Unfortunately, there are no on-line techniques for determining this most fundamental information. It now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. This paper presents the results for the development of a CT-based, on-line coal washability analyzer. The development of appropriate hardware and software necessary to adapt a CT analyzer for use in determining coal washability is discussed. Testing of the analyzer using well-characterized coal samples is presented.

Jan 1, 2000

By R. C. Milici

The primary factors that determine the marketability of coal from various supply centers in the U.S. are coal quality and supply; i.e. low sulfur, moderate- to high- Btu coals have large market areas when compared to less expensive but poorer quality coals. Price is the major factor in the competitive marketing of similar coal products. Good quality, (moderate- to high- Btu, low sulfur) coals from the Powder River and central Appalachian basins are marketed over large areas of the country, and central Appalachian coal is widely distributed in foreign markets, primarily as coking coal. In contrast, poorer quality bituminous coal (low calorific value and/or high sulfur) from the Illinois Basin, northern Appalachian Basin, and lignite from the Gulf Coast is marketed in or near the States in which it was mined even though the price at the mines may be lower than mine prices for central Appalachian coal. Widespread distribution of sub-bituminous Powder River Basin coal is enhanced by its exceptionally low mining costs, which offsets transportation costs to distant markets.

Jan 1, 2001

By Harry Asche

The last 12 months has seen the construction of the first Earth Pressure Balance (EPB) TBM excavated tunnel in New Zealand on the Project Hobson sewer storage tunnel for Watercare Services Limited, with the concurrent excavation of the second EPB tunnel on the Rosedale Outfall project for North Shore City Council. Together these tunnels involve a total length of 6km and follow an 8 year pause in TBM activity in Auckland. TBM performance on these two projects is thus of significant interest as there are four major tunneling projects totaling over NZ$8B being planned for Auckland, in similar ground conditions. Auckland?s bedrock is a weak sandstone/siltstone (East Coast Bays Formation), subject to infilled paleovalleys. The geology in the region has been significantly influenced by volcanic activity; 49 volcanoes are present within 20km of the city centre. The paper describes the design and construction challenges for the projects, including TBM performance, ?sticky spoil? management, and risks associated with basalt lava flows and two paleovalleys. Watercare?s Project Hobson also saw the successful implementation of a Geotechnical Baseline Report?one of the first uses of this type of document in Australasia. Rosedale Outfall is designed for high internal water pressures with varying hydraulic flows, with the risk of exfiltration explicitly addressed.

By M. Buxton

Sensor derived data can add value across the mining operating chain ranging from resource definition, extraction, pre ? concentration, mineral process monitoring and assessment of product quality. Most documented studies on the use of sensors in mining focus on specific technologies for specific applications. These studies do not take into account different aims, objectives and operating conditions at different steps in the value chain. The first part of this contribution assesses key physical performance and discriminatory requirements of sensors applied in each portion of the mining value chain. The second part proposes a framework of methods for quantifying the value added by additional sensor information. Integrating the sensor based technology and the economic value quantification allows for both, designing an economically optimal sensor monitoring network along the whole mining value chain and optimizing efficiencies. Illustrative studies demonstrate the significant economic benefits, in particular in reduction of exploration expenditures, increase in extraction efficiencies, increase in ore product quality and improvement of processing efficiencies.

Feb 27, 2013

By K. Biswas, F. C. Felipe

Paste backfill, because of its colloidal or water-holding properties, does not produce run-off water when placed underground. Paste backfill is generally, prepared from relatively low water content, full mill tailings with a certain proportion of ultra-fine particles and mixed with cement, thus producing early and better strength. Mill plant discharge tailings and other materials available at or near the mine site such as sand, aggregates or waste rock are used as blending materials in the mix design. This study investigates the influence of the above-mentioned blending materials on the mechanical characteristics of paste backfill, as well as the grading, shape, specific surface area, mineralogy and workability of the different mix design.

Jan 1, 2000

By Jeff Easton, J Johnson, D. Foot

The Mina Santa Rosa mine in Panama was the victim of a mine closure 24 years ago that left the community in dire straits. The mine showed the potential resources of greater than 1M ounces of gold and 4.5M ounces of silver. Veragold Mining Company decided to reopen the mine and address all the issues that were involved in the startup of an historic mine. This paper provides methods to restore the community trust, provide a transparent process, and develop an environmentally sound flowsheet. Immense scrutiny surrounded the Tailings Storage Facility, and the company developed a plan focused on paste thickening and surface stacking to eliminate the need for a conventional tailings’ facility. Paste thickener principles and benefits are also provided.

Feb 1, 2024

In 1988, at the request of members of the Society for Mining, Metallurgy, and Exploration (SME) Inc., the president of SME formed Working Party No. 79, Ore Reserve Definition. Its mission was to develop guidelines for the public reporting of exploration information, resources and reserves. These guidelines were published in the April 1991 issue of Mining Engineering (pp. 379-384), and as a document entitled “A Guide for Reporting Exploration Information, Resources, and Reserves” in January 1992. Work continued on an ad-hoc basis until 1996. Working Party No. 79 was then renamed the SME Committee on Resources and Reserves and became a standing committee.

Jan 1, 1999

This study was conducted to determine the effects of a machine-mounted scrubber and water sprays on face methane levels. Testing was conducted in the NIOSH ventilation test gallery which was designed to simulate a full-scale mine entry. In the test entry, a model mining machine, equipped with water sprays and a simulated dust scrubber, was located at the face of a 20-ft box cut. Blowing ventilation was provided using a curtain with a 40-ft setback distance. Methane released from a pipe manifold located inby the mining machine was monitored at six locations that were 1 ft outby the pipe manifold. Tests were first conducted to evaluate the effects of using sprays and scrubber separately on face methane levels. Additional tests were conducted to determine how a scrubber used with various water spray systems would affect face methane levels. The use of either sprays or scrubber reduced face methane levels significantly. The combined use of sprays with the scrubber further reduced face methane levels a small amount. Primarily the sprays affected methane levels by changing airflow distribution close to the face.

Jan 1, 2001

By Y. Topkaya, R. E. Johnson, D. Buttinelli, B. R. Palmer, A. Geveci, L. Stoppa, C. Lupi, F. Pochetti

Representative samples of a composite mixture of three typical Cu/Zn complex sulphide ores, namely Black-, Yellow- and Altered-ore, from the Cayeli deposit in Turkey, were used for leaching tests in 2.2 M FeCl3, or 1 M CuC12-2 M NaCl solution in the temperature range from 313 K to 363 K (40O to 90O C), with and without the presence of an organic solvent for elemental sulphur, such as CCl4. The leaching rates of copper and zinc were quite high, as expected, in FeCl3 solution and complete recovery of both metals was obtained at the highest temperature when the solvent was present. However in CuC1, solution, extraction yields of the order of 95% only for Cu and Zn were achieved and the positive effect of the solvent was not clearly shown. The kinetics curves of Cu leaching by FeCl3 indicated a model of reaction rate depending on the particle surface, as in a chemically controlled reaction, in tests with the presence of CCl4. Without the solvent, or in CuCl2 media, the model of the diffusion controlled reaction seemed to prevail. Values of apparent activation energy, in both of the leaching processes, were determined and compared with those reported in literature.

Jan 1, 1993

By S. Kittel, P. Galleguillos, H. E. Urtubia

The rougher flotation at Escondida consists of 80 cells of 100 m3 each, with injected air. Escondida has developed a system of automatic control of the rougher flotation using video cameras, which have been operating since 1997 for remote monitoring and manual control. Since 1999, an image processing software and a group of rules have allowed implementation of an expert system. To date, the expert system controls the superficial speed of each cell by adjusting the air flow and the froth depth of the flotation bank. Preliminary tests of the expert control on two of the eight rows gave 1.2% higher rougher recovery at a 92% degree of confidence. The proven benefits are already sufficient to move towards a complete plant implementation.

Jan 1, 2001