Search Documents

By Bruno Bussière, Michel Aubertin, Anne-Marie Dagenais, Johanne Cyr

A five steps remediation program was commissioned in 1998 for the acid generating Lorraine mine site, located in the Témiscamingue region, Quebec, Canada. It included, as the main expenditure, a cover with capillary barrier effects (CCBE) used to limit oxygen migration. After construction of the cover, instruments were installed on site to monitor the CCBE performance. Modified oxygen consumption tests were also done to measure the oxygen flux through the cover. Results from water content and suction data, measured from 1999 to 2003, show that the capillary barriers effects are effective and that the water retention layer stays near saturation throughout the years. Oxygen fluxes estimated from monthly water content measures are generally below 10 g/m2/year. Results from modified oxygen consumption tests made on the site give almost similar oxygen fluxes. A two dimension numerical model of the Lorraine mine site was also constructed to verify that mathematical models could predict realistically the in situ conditions on such a large scale site. Numerical results obtained for three years show a good concordance between measured and calculated values. The results obtained form these different evaluation methods for the performance of a CCBE concur and confirm the efficiency of this cover in limiting acid mine generation.

Jan 1, 2005

By A. L. Crandell

History The Cortez Mining District has a long history of mining activity dating back to 1862. More recently, Cortez Gold Mines had operated a cyanide leach, counter current decantation (CCD) recovery gold mill from January 1969 to February 1976. This type of plant has been standard in the US for treating higher grade, finely disseminated gold in Carlin type ores. The mill was initially operated from 1969 to 1973 at 1.5 kt/d (1650 stpd) on oxidized ore from the Cortez ore body. In 1973, the mill was operated at 2 kt/d (2200 stpd) on softer, less oxidized, high clay ore from Gold Acres, located 13 km (8 miles) west of Cortez, NV. In February 1976, the oxidized portion of the ore body at Gold Acres was depleted and the mill ceased operations. Successful heap leaching of the lower grade portion of the ores was practiced at both Cortez and Gold Acres to supplement the milling operations. Valuable experience was gained in the operation of these two heap leaching programs (Duncan and Smolik, 1977). The ore heaps at Gold Acres and Cortez were releached with a limited crew from 1976 to 1979. The surge in the price of gold in late 1979 sparked an interest to incorporate new techniques into treating lower grade and less oxidized carbonaceous ores at Cortez. In early 1980, heap leaching was started on low grade oxidized dump material left from the earlier Cortez mining operation. By June of 1980, testwork was completed on the London Extension Dump, a low grade, mildly carbonaceous dump at Gold Acres. It was decided to convert the mill at Cortez from the conventional cyanide leach CCD recovery plant to a carbon-in-leach (CIL) recovery system. In May 1983, ore processing from the Horse Canyon deposit began. The Horse Canyon ore body contains both oxide and carbonaceous ores and is located 22.5 km (14 miles) from the Cortez mill. The Cortez CIL circuit was expanded to handle a blend of oxide and carbonaceous ores from Horse Canyon. Ore selection In the last quarter 1979, gold prices were increasing to a point where restarting the Cortez mill, idled since 1976, appeared imminent. Several previously explored geologic reserves at various stages of development were available as possible sources of feed for the mill. Initial metallurgical testing of dumps and tailings from earlier operations was completed, and previously uneconomic deposits were explored. It was decided to pursue sources of ore with the least lead time to production and those with the least capital cost requirements. A master plan was developed to bring the four profitable ore resources into production. The plan called for: • Heap leaching of waste dumps from the Cortez mining operation; • Restarting the mill to handle the waste dumps from the London

Jan 9, 1986

By Robert A. Bauer, Paul B. DuMontelle

In 1985, participants of the multi-year Illinois Mine Subsidence Research Program conducted surveys of subsidence effects on crop production from current high-extraction mining methods, selected a site to characterize the profile, strain, fracture development in overburden materials and changes in aquifers produced by subsidence from high-extraction mining, characterized floor materia1 s in three mines, and established bibliographic reference and data base files. The Illinois State Geological Survey, University of Illinois at Urbana-Champaign, Southern Illinois University at Carbondale, Illinois Department of Mines and Minerals and Twin Cities Research Center of the U. S. Bureau of Mines are coordinating State and Federally funded research.

Jan 1, 1986

By U. Heuer, B. Rathmann

Many mining operations have gained an impressive expertise in trouble shooting and maintenance with their existing fleet over the years. Whether it is an in-house maintenance group or an external service group - most of the systems weak points are well known and can be corrected by maintenance personnel. As some of these issues get more and more serious each year, too much time is lost in unscheduled downtime, often taking hours to be repaired and to find the failure with obsolete diagnostic tools (Fig. 1.). Many of the breakdowns result from failures that cannot be detected in advance. The maintenance system is much more reactive than preventative. The state of the art of mining equipment today uses advanced, efficient, and reliable systems for electrical drives, control and diagnostics of the machines. The demand for highly sophisticated solutions on such mining equipment is well known. Mining operators need to ensure the highest level of productivity, lowest operating costs, least maintenance and highest reliability in a drive system. The paper will introduce you to the state of the art of drives technology for dragline (Fig. 2) and shovel mining equipment (Fig. 3).

Jan 1, 2007

By P. Bester, G. J. van der Linde

Foskor operates a mine in the Northern Province of the Republic of South Africa exploiting the igneous complex at Phalaborwa. It produces about 3 million tons of phosphate concentrate per year by means of froth flotation from 26million tons of ore of which 16 million is mined and milled onsite. The remaining 10 million tons originate at the Palabora Mining Company and is pumped as a slurry to Foskor. Two types of ore are mined and milled namely Foskorite and Pyroxenite. (The main mineral content of this ore is Apatite, Phlogopite and Diopside.) After three stages of crushing the ore is milled using 24 rod mills and 5 verti mills. The apatite is then recovered using four stages of froth flotation. The stocks of Foskorite ore are rapidly being depleted and the PMC tailings will also fall away by the year 2002 so that the whole mining operation will then be centred around the Pyroxenite ore. This will lead to substantial increases inproduction costs. The recoveries achieved in the flotation plant are largely dependent on the successful operation of the comminution section. Parts of this plant are now 35 years old and the advantages of re-engineering, new technology and automation can only be applied to a limited extent in an effort to reduce costs. It was then decided to investigate alternative milling methods, both wet and dry.

Jan 1, 1999

By H. Maleki

In this paper, long-term measurements in five underground mines are presented to demonstrate how these measurements can be applied to stability evaluations and design of underground excavations. These case studies address both the global aspects of strata response to mining activities as well local ground behavior and support loading. The measurements include static (stress and deformation) and geophysical. Case studies quantify pillar behavior, roof-floor deformation patterns, overburden response, and microseismic activities. Large-scale studies quantify the nonuniform nature of overburden deformation and collapse. Local measurements address yield and stable pillar load deformation characteristics, as well as the performance of support systems under combined axial and lateral loads.

Jan 1, 2002

By Colin Rawlings, Simon Pepper, Maria Karakitsiou, John Mathews, Peter Townsend, Russell Bowler, David Keeble, Christopher Darton, Scott Sadler

National Grid needs to maintain a connection between two existing electricity sub-stations (Beddington & Rowdown) in the Croydon (south London) area, and allow the replacement of two 275 kV cable circuits that are buried under roads. This is to be achieved using a single 400 kV cable circuit within a 10 km (6.25 mile) long, 3 m (9.8 ft) diameter high voltage cable tunnel which is being driven through water bearing Chalk, at depths ranging from 5 m (15 ft) to 80 m (262 ft), with four access shafts(12.5 m (41 ft) in diameter) ranging in depth from 10 m (31 ft) to 40 m (131 ft). The Chalk in this area acts as a source of public drinking water supply (PWS) and is protected by areas designated Groundwater Source Protection Zones. To minimise the groundwater risk the design and construction of the cable tunnel and shafts has paid particular attention to the construction materials used, including testing of these construction materials prior to use, developing construction methods (including the design of the Earth Pressure Balance TBM) and maintaining a groundwater monitoring & testing programme prior to and during construction to ensure the integrity of the Chalk aquifer is maintained as a drinking water source. This paper describes the tunnel &shaft design and construction in relation to these particular groundwater environmental issues which set new precedents for tunnel assessment, design and construction requirements in the United Kingdom.

Jan 1, 2007

By T. J. Lutz, D. S. Yantek, L. Yan, J. R. Srednicki, J. A. Yonkey, G. T. Homce

Federal regulations require the installation of refuge alternatives in underground coal mines. Of the inuse refuge alternatives, more than 95 percent are mobile refuge alternatives, with the remainder being built-in-place (BIP) refuge alternatives. Heat/humidity buildup has been one of the major concerns with mobile refuge alternatives. For BIP refuge alternatives, however, there is a lack of in-mine heat/humidity test data to determine the extent of heat and humidity buildup. To quantify heat/humidity buildup in BIP refuge alternatives, the U.S. National Institute for Occupational Safety and Health (NIOSH) performed a series of heat/humidity tests on a 60-person BIP refuge alternative with and without a borehole air supply. At various times during the year, tests were performed with cooled, heated or unconditioned borehole air to examine how various outdoor temperatures may affect the thermal conditions inside a BIP refuge alternative. The results show that the air supplied to a BIP refuge alternative may require heating or cooling, depending on the outside air temperatures and the temperature of the mine. For example, during tests with an external ambient temperature above 21 °C (70 °F) and a relative humidity of 90 percent, providing 13 °C (55 °F) dew point air at 775 scfm, which is slightly higher than the mandated flow rate of 12.5 scfm per person, kept the internal apparent temperature below the mandated 35 °C (95 °F). Results for each test case are presented.

Jan 1, 2018

By Edward DeLilla

For the past 30 years, surface mines have moved toward more highly mechanized, automatic systems that continuously mine overburden and ore to increase productivity, lower operating costs and minimize manpower needs. To achieve these goals, mine operators must be involved in every step of the machine procurement process. Several factors are involved in making the machines operate economically and efficiently: -Prudent engineering. -Proper planning. -Realistic feasibility studies. -Effective specification. -Thorough training of the mine personnel.

Jan 1, 1994

By Thomas N. Walthier

This paper will review world trends that are increasingly restrictive of mineral exploration and mining throughout the Free World This is occurring in the face of projected huge increases in demand for mineral products Some of the impediments are direct and absolute; others are indirect, but nevertheless effective; still others represent merely hostile attitudes Many of the world governments have a reputation for lack of integrity in dealing with existing foreign investments within their borders, and consequently are quite uninviting places for new investments, especially in the capital intensive natural resources industry. Compared with even 35 odd years ago (and pre-World War II is not that long ago) there are few places left where private mining investments are both wanted and where investors are willing, to go. We shall begin with an analysis of conditions in the U. S., shift to neighboring Canada and Flexico, and then have a look around the world. As the world grows smaller for the private mining sector, the function of exploration, development, and operation is passing over to government. We'll conclude with a view of what this holds for the future

Jan 1, 1976

By Ping K. Di

A naturally aged and synthesized manganese oxide-coated granular media was found in our laboratory to have the capability of the removal of soluble Mn(H) from mine drainage by adsorption and oxidation. Mine drainage commonly also includes other heavy metal ions. Extending this principle, this paper presents the removal of heavy metals including lead, copper, cobalt, zinc and nickel in the aqueous solution by using the synthesized manganese oxide-coated granular media. It was found that the adsorption of lead, copper, cobalt, zinc and nickel on the manganese oxide-coated media follows both Langmuir and Dubinin-Radushkevich adsorption isotherms except in the concentration range less than 0.1 mmole/L. The adsorption mechanism involves the ion exchange between the heavy metal ions and synthesized manganese oxide coated on the media. The synthetic manganese oxide surface has a strong metal binding ability to the heavy metals in the order of Pb2+ > Cu2+ > Ni2+ > Zn2+ > C02+ based on the adsorption results using batch and continuous column operations. The breakthrough curves of these heavy metals showed that the synthesized media could be used effectively in the removal of these heavy metal ions in a cell or packed column. The process can simultaneously facilitate the immobilization of the heavy metals on the synthesized manganese oxide coated media. A subsequent pH adjustment dislodges the heavy metals and regenerates the synthetic media. Thus, the process accomplishes the adsorption, immobilization and concentration of the heavy metal from waste stream in one monolithic procedure.

Jan 1, 1995

By Robert Harris, David Duncan

The Samira Hill gold mine represents the first commercial gold project for the landlocked country of Niger in West Africa. It began production in October 2004 as the result of over 10 years of exploration and development work. There were several administrative, social and technical challenges that had to be overcome to realize the successful development of the project. The Samira mine is located on the geological structure known as the ‘Samira Horizon’ which is developing as a promising district for additional discoveries and other mine developments.

Jan 1, 2005

By Christophe Bragard

The Los Angeles Metro Eastside Extension light rail project included a 1.5 mile underground segment, which consisted of twin 18'?10" ID tunnels, bored with two EPB-TBMs. One of the major project challenges after the completion of the bored tunnels was the excavation of six cross passages within alluvial geology below the water table and with low ground cover. Sequential excavation methods were employed and this paper details the design, ground treatment, support measures, and construction methods used to mine these cross passages beneath the congested urban streets of the City of Los Angeles.

Jan 1, 2008

By A. J. Hendron, J. E. Monsees

INTRODUCTION This paper is the outgrowth of work done by the authors to prepare the seismic design criteria for underground structures on the Southern California Rapid Transit District (SCRTD) Metro Rail Project. It is a follow-on to a similar paper presented at the October, 1984, ASCE National Convention (17). For design, the earthquake-induced distortions recommended herein are to be added to the normal static loading conditions for the underground structure. This design approach has been used by 18 section designers on the SCRTD Project. Preliminary results from two- and three-dimensional finite element solutions have partially verified the approach. Areas where additional research is needed for special cases are identified. EFFECTS OF EARTHQUAKE The effects of earthquakes on underground structures may be broadly grouped into two general classes -shaking and faulting. In response to earthquake motion of bedrock (shaking) , the soil transmits energy by waves. Seismologists identify various types of earthquake waves, but underground engineers are generally interested in the effects of transverse shear waves which produce a displacement of the ground transverse to the axis of wave propagation. The orientation of propagation is generally random with respect to any specific structure. Waves

Jan 1, 1985

The 23rd annual American Mining Hall of Fame Awards Banquet sponsored by the Mining Foundation of the Southwest will be held at the Tucson Marriott University Park Hotel, Tucson, AZ on Saturday, Dec. 3, 2005. The Mining Foundation of the Southwest is a non-profit organization. It educates the public about the mineral industries and reports outstanding accomplishments in the fields of mining and the earth sciences. This year’s inductee, guest of honor and featured speaker at the banquet will be Pierre Lassonde, president of Newmont Mining and resident of the World Gold Council. He is one of Canada’s leading gold analysts.

Jan 1, 2005

By Scott Ellenbecker

Soon New York City will have a new train station. A tunnel project is under construction to extend Line 7 to a new station that is located near the Jacob K. Javits Con-vention Center. This is also part of the Hudson Yards redevelopment project that is intended to aid redevelop-ment of the west side of Midtown Manhattan around the Long Island Railroad?s Caemmerer Railyard. The station, or ?cavern? as it?s called by those excavating it, will be the portal for that growth. In the city, public transportation means high-rise residential proper-ties will have better access to the business district, and those outside the area will have greater access to event facilities ? two factors that are critical for development investment.

Jan 3, 2010

By Paul D. Tomlingson

Part two of this two-part series covers the use of an integrated information system with administrative information, including error and absentee reports as well as open work files. Part one (ME, July, page 650) discussed conceptualizing and developing a maintenance information system. It explained what information is needed to manage such a system.

Jan 8, 1985

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 QUANWEN PU, Yonggang Wei, Bo Li

The spent catalyst is one of solid waste resources, which contains precious metals with considerable recovery value. However, due to the different compositions of catalyst, the recovery process is difficult. Most of the catalysts are supported by alumina which has good alkali-soluble properties, while platinum is insoluble in alkali. Platinum is enriched by pressurized alkaline solution which is a kind of hydrometallurgical process. The novelty of this study is the separation of alumina and platinum from the spent catalyst and the enrichment of platinum in the solid phase. In this study, a leaching process using NaOH as leaching agent under high temperature and pressure was employed. The effects of alkali concentration, leaching temperature, leaching time, and liquid–solid ratio on leaching efficiency were investigated. The optimum process conditions were determined as follows: alkali concentration of 240 g/L, temperature of 200℃, pressure of 1.20 MPa, time of 1 h, liquid–solid ratio of 5:1. It was concluded that the leaching rate of alumina can reach 99.69%. The content of platinum increased from 0.1749 to 21.12%, the loss of platinum was 3.39%, and the enrichment ratio of platinum increased by 120.82 times. The leaching kinetics of alumina was studied based on the shrinkage core model. The activation energy of alumina leaching is 19.53 kJ/mol, and the leaching process is controlled by chemical reaction. Pressurized alkali solution can not only efficiently leachate alumina from the spent catalyst and enrich platinum, but also reduce the reaction time and increase reaction rate.

Feb 11, 2022

By T. McKeon

Gravity separators are commonly used in multistage cleaning and scavenging circuits to improve the quality and/or recovery of the final concentrate. Unfortunately, studies suggest that many industrial plants are poorly designed in terms of equipment layout. This shortcoming can often be attributed to a failure by engineers to make use of fundamental process engineering tools for circuit design. One of the most important of these is linear circuit analysis. This powerful tool makes it possible to mathematically compare the relative efficiencies of circuit configurations in advance of experimental testing. This article provides a basic review of the linear circuit analysis concept and discusses some of the key insights it provides for the layout of multistage circuits. An industrial case study is provided to show the tremendous impact that this process engineering tool can have on the design of multistage spiral circuits in a heavy mineral wet plant.

Jan 1, 2005