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By B. A. Filas, H. N. Lammers

Responsible environmental, social, and governance (ESG) practices are not new to mining. It is the ESG acronym that has become the “flavor-of-the-day” with the stock markets, accounting firms, and investment strategists. This increased interest from the financial sector has heightened executive awareness and accountability to where corporate leadership and directors are proactively prioritizing ESG issues from the top down within their companies. This paper aims to convey what the authors believe one needs to know to be able to conduct and prepare effective ESG audits and reports. The emphasis is on how ESG fits within the mining sector, some of the ways that many mining companies have been practicing ESG responsibility for decades, the importance of effective communications with stakeholders, and the roles that regulatory and international lending institutions play in enhancing ESG practice on a global scale as a precursor to the discussion on ESG auditing and reporting. Without this background, the ESG audit may become a purely academic exercise.

Feb 1, 2023

By J. F. T. Agapito

OCI Wyoming mines two flat-lying trona seams that are 3- to 3.5-m- (10- to 11.5-ft-) thick, about10 m (33 ft) apart and 250-m- (820-ft-) deep at its Big Island Mine in Wyoming. Continuous miners and a yielding-pillar system have contributed to improvements in resource recovery and productivity. The use of yield pillars minimizes the stresses transmitted from the upper to the lower seam. However, yielding must not impact the good, long-term stability needed to prevent subsidence for a large portion of the mine beneath the Green River channel.

Jan 1, 2000

By Joseph Kuti

Longwall mining is the term used for the underground extraction of a wide and deep panel of coal. Such a panel may be blocked out by one or more entries on either side ("head" and "tail") of a longwall face. If all the entries are pre-driven, the panel extraction is termed longwall retreat mining. With one exception, all the longwall faces in the United States are of this type. (1) prior to the general decline in the rates of production with Continuous Miners, the development of the multiple entries generally kept ahead of the longwall extraction rate. This is no longer the case: longwall extraction rates far exceed the rate of development. In addition to this problem, in newly established mines, the development of a haulage and bleeder system based on multiple entries results in a lead-time of three years or more before longwall mining can be applied. This is one reason why earlier projections and much of the optimism attached to longwall mining as a principal "savior" in the energy crisis should be viewed with some caution.

Jan 1, 1978

By Martín Antonio Encinas‐Romero, Patricia Guerrero‐Germán, Jesús Leobardo Valenzuela‐García, José R. Parga‐Torres, María A. Bracamontes‐Landavazo, Agustín Gómez‐Alvarez

A study was carried out to process a sulfide mineral concentrate from Norwest of Mexico containing 97 g/t Au, 0.15% Cu, and 15% Fe. An oxidative acid pretreatment was investigated using ferric sulfate as oxidant, followed by leaching of gold with sodium cyanide. Scanning electron microscopy, SEM-EDS, and X-ray diffraction, XRD, the analysis confirms the presence of quartz and pyrite species. First, a leaching was carried out without pretreatment, at ambient conditions, T = 25 °C and P = 1 atm, obtaining only a 45.2% gold extraction. Once the presence of Fe and Cu sulfides had been confirmed, the Eh-pH diagrams were constructed for the Fe-S-H2O and Cu-S-H2O systems, where it is appreciated that pyrite and chalcocite can dissolve with high oxidation potentials and forming sulfur, oxidizing to sulfate at highly acidic conditions. The oxidized concentrate was neutralized and adjusted to pH > 10.5; it was leached at ambient conditions, at different particle sizes, 44, 37, and 26.5μm, achieving an Au extraction of 75% using a concentration of 0.5% NaCN, 26.5μm particle size, 20% solids, and P = 1atm. Then the oxidized material was subjected to different temperatures, 25, 50, and 70 °C, under the same conditions and obtaining Au extractions up to 92% at 70°C. Additionally, the leaching process was compared using an autoclave reactor at moderate pressures, obtaining an increase in the extraction of Au up to 98% in 2 h, at T = 70 °C and P = 0.62 MPa.

Jan 23, 2022

By James D. Bliss

Sedimentary deposits of pluvial Lake Bonneville are an important source of sand and gravel suitable for aggregate and construction in Utah. Data on Lake Bonneville basin sand and gravel deposit thickness, volume, grain size, percent of fines, and durability were statistically analyzed to detect variations associated with geologic domains, geographic location, Lake Bonneville shorelines, and sand and gravel deposit type, and to construct quantitative deposit models. Analysis showed several trends; (1) sand and gravel in younger shorelines was slightly more durable and the deposits considerably larger in volume, (2) younger shore- lines are also more likely to contain more than one genetic deposit type, (3) the volume of terrace deposits is larger than beach deposits, (4) terraces and beaches are generally thicker than spits and bars, (5) the northern part of the Bonneville Basin contains slightly more durable sand and gravel than the southern part of the basin and is more likely to contain deposits composed of more than one genetic deposit type, aid (6) the Wasatch domain deposits are composed of more than one genetic deposit type more often than deposits of the Basin and Range domain. Three additional conclusions with immediate economic significance are; (1) the median sand and gravel deposit in the Wasatch domain, 360,000 m3 (275,000 yd3), is three times larger than that of the Basin and Range domain (120,000 m3 [90,000 yd3]), (2) the median deposit thickness in the Wasatch domain, 5.8 m (19.0 ft), is nearly twice that of the Basin and Range domain (3 m [lo ft]), and (3) the Wasatch domain also contains slightly larger diameter gravel. These three conclusions are significant because the trend for sand and gravel development in the Bonneville Basin is to move from the Wasatch domain to the Basin and Range domain. Smaller, thinner deposits with smaller diameter gravel will require more surface area to mine than would have been necessary in the Wasatch domain. The result is a higher cost for sand and gravel in construction projects in the Salt Lake City area, especially since the gravel must also be hauled farther.

Jan 1, 2001

By William A. Hustrulid

The subject of surface mine development is large. This section covers the fundamental concepts involved in both the open pit mining of thick or steeply dipping deposits as well as the strip mining of thin, shallow, and relatively flat-lying seams or beds. Design involves the marrying of geometries, ore and waste characteristics, equipment, and economics so that the desired result is achieved. Generally, there are many possible combinations from which to choose. For example, extraction over a short time period requires one strategy while quite another is applied for longer times. Variations in supply and demand require some flexibility of operation. Customer requirements impose certain constraints regarding the set of possible designs. Over recent years, planning and operating considerations for surface mining imposed by environmental requirements have increased markedly. There have, at the same time, been enormous advances made in the design aids available to the mine planner. Computer simulation of the various options, whether it be for mine design or equipment selection, provides detailed information for decision making in real time. A significant challenge to the engineer/planner is how to best use the aids avail-able. Because of the widespread use of commercially available and in-house computer software by industry, this section does not deal with the details of planning (for basic coverage of mine development, see Section 7). Rather, some of the basic concepts are stressed. The principles involved in equipment sizing and selection are discussed. A highly important but sometimes over-looked aspect of planning, haul road design, is also covered. For surface mining operations of the future, in-pit crushing and conveying will become even more important. Some of the considerations for application evaluation are included. The section concludes with some future concepts for surface mining.

Jan 1, 2008

By K. Muralidharan, P. R. Rao, M. Momayez, K. A. Runge

The evolution of trapped geothermal heat in hot underground mine along with emission of toxic gases and dust during mine activity makes the mine environment unfavorable is hazardous to worker’s health. This imposes significant demand on cooling and ventilation systems. As a result, substantial costs are incurred while implementing environmental regulation processes to dissipate the heat and provide comfortable working conditions. Thus, as an alternative, the development of cost effective materials to act as efficient thermal insulators is on the rise. Thermal conductivity is an important property that is a direct measure of a material’s ability to facilitate/deter heat flow. In addition to their superior chemical resistance, adequate mechanical strength, abrasion and fire retardant as well as environmental benefits in comparison to existing building materials such as ordinary Portland cement, aluminosilicate based geopolymers are now gaining widespread interest as promising thermally insulating and sustainable materials. This paper begins with an overview of geopolymers, transitioning into a discussion of recent developments in the field of geopolymer development as a thermally insulating material broadly classified into: filled geopolymers and porous geopolymers resulting in structures with enhanced ability to impede heat flow.

May 9, 2020

By Joseph J. Feiler

Fires in underground coal mines are persistent problems anywhere in the world that coal is mined. Coal fires pose safety and health hazards in the form of mine subsidence, loss of energy reserves, destruction of property and surface improvements, and air pollution. In 1995, the US Bureau of Mines (US-BM), in cooperation with the Colorado Division of Minerals and Geology (CDMG),entered into a contract with Goodson & Associates Inc. (GAI) to design and field test the effectiveness of a new foamed grout technology called ThermoCell. GAI is a Lakewood, CO geotechnical and mining reclamation engineering firm. The company developed ThermoCell to control and extinguish underground coal fires. The viability of the special grout and the technology of application were established during a full-scale field demonstration at the abandoned IHI Coal Mine fire, near Rifle, CO. Following acquisition of additional funding by CDMG in 1999, Goodson returned to the site in April to continue the grouting to fully extinguish the IHI fire.

Jan 1, 2000

By V. Rajagopal

Corrosion and abrasion properties of a series of chromium-containing cast iron balls with Cr contents ranging from 0 to 29% was evaluated and compared with austenitic stainless steel and mild steel balls. Marked ball wear tests were performed on artificial ore samples consisting of 95% quartzite with either 5% pyrrhotite or 5% chalcopyrite under a nitrogen or oxygen atmosphere. The electrochemical mechanism was investigated by correlating the corrosive wear with the corrosion currents obtained from potentiodynamic polarization curves under abrasion. An offset in their electrochemical activities was observed somewhere between 16 and 26% Cr. In fact, 26 and 29% Cr cast irons showed an excellent corrosion resistance approaching that of austenitic stainless steel. Flotation recoveries were estimated on a 95% quartzite + 5% pyrrhotite sample ground with various cast iron ball materials under an oxygen or nitrogen atmosphere. Electrochemical results are found to be in good agreement with corrosive wear obtained from marked ball wear test and with flotation results.

Jan 1, 1991

By David L. Hill

Newmont Gold Company's Mill No. 4 is located along the Carlin trend, about 25 miles North of Carlin, Nevada. The plant consists of a primary grinding circuit using a 7.2 m (22 ft) diameter by 2.6 m (8 ft) long semi-autogenous mill along with a 2.3 m (7 ft) diameter cone crusher. Secondary grinding is performed in a 4.8 m (14.5 ft) diameter by 9.2 m (28 ft) long overflow ball mill in closed circuit with a set of 66 cm (26 in) diameter cyclones. The ground product is fed to a typical carbon-in-leach gold leach circuit. The grinding/crushing circuit operation and control scheme are the topics of this paper.

Jan 1, 1993

The Canadian concept for nuclear fuel waste disposal is being assessed by AECL Research in a series of experiments at its Underground Research Laboratory (URL) near Lac du Bonnet. Manitoba, Canada. As pan of this research, the Mine-by Experiment has been designed to obtain information on rock mass behavior, the development of an excavation-induced damage zone and failure mechanisms around a circular bored tunnel. An iterative design approach was used to effectively reconcile the experiment objectives and construction logistics. This paper discusses the design considerations and construction methodology adopted on the project.

Jan 1, 1991

By R. L. Brown

The Buchans mining district is located roughly at the center of the island of Newfoundland and contains some 18 separate mineral deposits. The first of these deposits was discovered in 1905, the latest discovery having been made in 1979. To the present (1983), some 16 Mt (17.7 million st) grading 1.33% Cu, 7.5% Pb, 14.5% Zn, 115 g/ t (3.7 oz per ton) Ag, and 1.4 g/t (0.04 oz per ton) Au have been mined. Mining operations are now largely terminated, but a few hundred thousand tons of economically marginal reserves may be mined in a salvage operation. The Geological Association of Canada Special Paper No. 22, "The Buchans Orebodies, 50 years of Mining and Exploration," contains papers which describe the history, geology, and the application of evolving geological concepts in exploration. Papers by Neary, Swanson, and Thurlow and Swanson in that volume are topical to the present discussion. Successful exploration techniques at Buchans included physical prospecting, utilization of the state-of-the-art geophysical techniques, saturation diamond drilling which was made possible by the high gross value of the existing ore, and, since 1955, diamond drilling directed by fairly well understood geological parameters. The record of discovery started in 1905 when the Buchans River deposit was found by Matty Mitchell, a prospector employed by the Anglo- Newfoundland Development Co., a British company which owned mineral rights over a very large area in the Red Indian Lake-Exploits River drainage system.

Jan 1, 1991

By Bruce Gellar

In March, the Prospectors and Developers Association of Canada (PDAC) held its annual conference in Toronto, Ontario. This is the third PDAC meeting the author has attended. The following are some impressions of the meeting. And the author looks forward to the joint meeting of the PDAC and the Canadian Institute of Mining, Metallurgy and Petroleum to be held March 5-10, 2000, entitled Mining Millennium 2000. One of the features of next year’s gathering is a proposed forum of world mining ministers, the first ever to be held anywhere.

Jan 1, 1999

By Leonard N. Hill

Cyprus Sierrita Corp. has 16 parallel 5.03 m-diam x 5.8 m long (16.5 ft-diam x 19 ft) primary ball mills, each operating in closed circuit with a nest of cyclones. Before the upgrade to 840 mm (33 in.) cyclones, each mill operated with a nest of five 660 mm (26 in.) cyclones - four in use and one on standby. In this configuration, the mill throughput was 88.5 kt/d (97,500 stpd). Flotation feed averaged 25.9% +212 pm (+65 mesh). The 660 mm (26 in.) cyclones normally operated at an inlet pressure of 34 kPa (5 psi), lower than the inlet pressure of 55 kPa (8 psi) recommended by the manufacturer. The circuit was typically operated with cyclone overflow densities greater than 40% solids to achieve the required throughput. This resulted in inefficient cyclone operation and excessive coarse oversize reporting to flotation. The apexes choked frequently. Larger apexes were tested but reduced the classification efficiency and resulted in circulating loads greater than 800%.

Jan 1, 1994

By Ebrahim Farrokh

Ghomroud water conveyance tunnel project is under construction using shield Tunnel Boring Machines (TBM) for a total length in excess of 50 km. Phase 1 of the project included 36 km of tunnel divided into four lots (1, 2, 3, and 4) of nine km each. Lots 3 and 4 of this tunnel for a total length of 18 km were combined into one award and have been constructed using a double shield (DS) TBM or one path system. Extreme ground convergence in some sections of the tunnel has stalled TBM performance in early reaches, due to face collapse and shield jammings. This paper presents the latest update on the tunnel progress and impact of ground convergence on machine performance based on the information obtained from field observations. Also, the method and results of tunnel convergence measurements were studied in conjunction with geological parameters and an attempt was made to correlate TBM operational parameters and ground convergence. The result of the analysis indicates a good correlation between machine?s operational parameter and tunnel convergence and can be used as an indicator of the potential for high rates of convergence. An early warning on ground convergence is essential for taking precautionary measures to avoid TBM jamming and related long delays and costs.

By D. J. Pyra, J. Kudelko, Korzekwam W.

Polkowice region (Lower Silesia, Poland) is an area, where the copper mining activity started about 40 years ago and new technologies were applied. There are 3 underground mines, 3 processing plants, tailings pond (the biggest one in Europe), pipelines for flotation waste transport, railways. Although new technologies were applied during the copper ore exploitation, the environment in this area were polluted mostly by dust containing copper, lead, zinc and arsenic. Estimated values of heavy metals in polluted soils were compared to the natural contents of this metals. The geochemical background for Polkowice area was defined. The pollution zones occur around mining facilities. Copper ore exploitation and processing is planned for the next 20-40 years depending on market situation. After mines and other facilities closing the most important problem will be sustainable development of this area. To evaluate the scope of revitalization activities the analysis of recent soil environment condition will be necessary as well as forecasts for pollution migration. Geostatistic methods used also in mining will be very helpful for this task.

Jan 1, 2005

By S. R. S. Sastri

By using the data of E.A. Hersam and F.C. Bond's equation for energy consumption in comminution, a method was developed to analyze the performance of industrial jaw crushers. The study showed that industrial jaw crushers are generally operated below capacity. The study also showed that industrial jaw crushers generally have sufficient installed power to operate at, full capacity. The method presented can be used to estimate the capacities and power requirements of jaw crushers.

Jan 1, 1995

By Richard E. Thill

Engineering properties of rock are essential in most phases of mining from site reconnaissance through mineral processing. Review of the literature indicates, however, that property data is scarce for most coal measure rocks in the United States. The Bureau of Mines, U.S. Department of the Interior, has undertaken a wide-ranging testing program to provide more complete property data for coal strata in the U.S. coal basins. The property data are expected to have application in geophysical exploration, the development of pre- mining and hazard detection probes and instrumentation, mine design, engineering and rock mass classification, subsidence engineering, and ground control. This paper describes the comprehensive program encompassing in situ geological, geophysical, and geotechnical properties and laboratory determinations of acoustic, electromagnetic, physical, mechanical, and index properties and discusses results for 500 ft of coal measures at a minesite in the Northern Appalachian, Eastern Coal Province.

Jan 1, 1982

By G. Miller

The design of solvent extraction plants has been generally based on the assumption of steady operating conditions in both the settler and the mixers. Recent experience with both large and small plants has shown that this is not the case. Mixer transients include start up aqueous locking and partial phase separation in secondary mixers. Both of these lead to either reduced plant capacity or overflow of upstream mixers. Analysis of the hydraulic pressure profiles has generated new design methods to eliminate the effects of the partial or complete phase separation. Further, changes to the method of specification and selection of both primary and secondary mixers have been made to eliminate the onset of partial separation during operation. Observation of settler operation has shown that it is also a dynamic process, even under ‘steady state’ conditions. Four different transient phenomena have been identified that lead to internal circulating flows, poor disengagement of fine secondary haze, and erratic and high entrainment levels in the discharges. A first approximation analysis has shown that there are significant pressure differentials within settlers and these change along the length and with phase separation rates. A technique to control the effects of these transients has been developed which allows plant performance to be improved beyond ‘standard’ expectations. The design and selection of the settler internals is described.

Jan 1, 2001

By James Warner, Peggy Ganse, Glen Smoak, Raymond Henn, Sam Bandimere

Over the past several decades, cement-based grouts using ultrafine cement as are placement for portland cement have begun to gain acceptance as an alternative to chemical solution grouts, however the amount of information currently available on these grouts is limited. For this reason, the authors developed a field testing program to evaluate the penetration capabilities of various ultrafine cement grout mixes. The tests were conducted by injecting sand columns using different portland and ultrafine based grouts, the measuring penetration distances after applying equal injection pressure for the same time period. Results of tests performed in 1999 and 2000 are discussed herein.

Jan 1, 2001