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By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi

The abstract highlights the impact of flocculants used in the middle thickener of a copper-molybdenum plant on both process water quality and molybdenite floatability. The study investigates the effect of a starch-based flocculant (wheat starch) on the efficiency of the middle thickener and molybdenite flotation. The findings indicate that the presence of starch influences the settling behavior of particles with different shapes, and the dosage of starch affects both molybdenum recovery and the presence of copper minerals in the molybdenum concentrate.

Mar 7, 2022

By D. J. Bryden, J. W. Oberholzer

In response to the need for enhanced precautionary measures to safeguard mine workers in collieries from the consequences of methane ignitions in a heading, the coal mining industry has ex- pressed the desire for the development and testing of active on board suppression systems. As overseas systems cannot be used directly in the bord and pillar geometry it is necessary to adapt overseas and local technology to suit local mining conditions, as well as to test such developed systems for their compliance with the expressed needs. As the systems have to be tested in a specific roadway configuration, a facility was developed to enable the testing in South Africa. A surface test facility has been established which can be used to develop and test suppression systems on continuous miners and roadheaders. This facility consists of a tunnel wherein compliance tests can be conducted in simulated underground conditions. A number of methane explosion tests have been conducted in the test facility. The explosions conducted varied in CH,/air concentration (7,5 to 9 percent) and volume (26 to 88 m3). At lower concentrations there was a marked reduction in explosion strength and flame speed. Tests carried out with the Explostop system successfully suppressed the propagation of methane ignitions in both scenarios tested.

Jan 1, 1997

By George H. K. Schenck

The North American-based mining engineer needs to understand the differences that exist between mechanical mining or boring machines built on this continent and those built in Europe. The differences Ere most clearly seen when machines for large-sized openings--about 15 feet high-are considered. This report will focus on the innovations of European origin. The rock-breaking tool, drag bit, or roller cone that is efficient for a particular project is related directly to the strength of the rock involved. This strength is generally stated in reference to the rock's unconfined compressivee strength in pounds per square inch (psi) although it is well recognized that a rock's shear strength is also important. Compressive strength has been adopted because it is simple to test for and provides a convenient comparison. Table 1 relates cutter type to compressive strength and indicates the general nature of the machine innovation devel¬oped in Europe.

Jan 1, 1970

By J. A. Madonna

Universities and colleges in three countries -Australia, Canada and the United States, recognized the need to establish and reorganize geoscience programs at the vocational and two-year technical levels. To accomplish this goal, a cooperative study with industry in one state or province from each country was initiated. These include 1) Tasmania, Australia, 2) British Columbia, Canada and 3) Alaska, United States. Over one hundred mineral exploration companies and private consultants cooperated in the study by providing information regarding their specific training needs for support personnel, the data gathered has been used to identify training area for semi-skilled, skilled and technical personnel in geophysics, including, but not limited to, geo-logical skills, geophysical skills, surveying skills, environ-mental skills, and computer skills. With areas of major educational need defined for geophysical exploration, an educational field skills model has been developed for the three levels of training. The depth of each level of education and the training objectives for the work force at each level will he discussed.

Jan 1, 1992

By Verya Nasri, Agustin Rey

Once completed, the Montreal Réseau Express Métropolitain (REM) will be the fourth largest automated transportation system in the world. The REM represents construction costs of approximately 7.0 billion Canadian dollars. The project consists of 67 km of twin tracks over four branches connected to downtown Montreal. The project includes 26 stations with 3 underground stations in downtown Montreal. One of the underground stations was built using the NATM method with thin permanent shotcrete initial and final liners separated by a sprayed on waterproofing membrane. The 2 other underground stations were built with the cut and cover approach including one using permanent secant pile wall with permanent walers and struts as the support of excavation and the final perimeter wall of the station. The project also includes the rehabilitation and enlargement of the Mont Royal Tunnel. This 100-year-old double track tunnel is about 5 km long. The REM also consists of 3.6 km new TBM tunnel connecting downtown to the Montreal International Airport through saturated soft ground and karstic rock. By the time of RETC, the construction of REM underground structures will be completed. This paper presents the design and construction aspects of the underground structures of this mega project.

Jun 13, 2023

By James J. Scott

I welcome this opportunity to speak before the Coal Division of the AIME in such an attractive setting as the Pacific Northwest. With the development of the Centralia project, the Pacific Northwest will have its first major coal-fired thermal electric generating plant. This State has a long history of coal mining that diminished with the passage of coal-fired steamships and locomotives but is now reviving with the growth of electrical power demand. Because this 1,400 row plant is to be supplied with surface-mined coal, it is particularly appropriate that this area be the setting for a talk on factors influencing the growth of surface coal mining in the West. During the course of my talk, I will touch on a number of factors including electric power demand, coal resources, production trends, environmental considerations and trends in State and Federal activities that I feel will influence surface coal mining in the West. Total electric power consumption by the year 2000 is expected to reach 9.4 trillion kilowatt-hours. Predictions of total coal consumption for electric power generation by that year range from a low of 845 million tons to a high of 1,520 million tons, or 2.6 to 4.7 times the amount used for this purpose in 1970.

Jan 1, 1971

By Paul H. Johnson

Chemical mining may be defined as the in-place extraction of metal values from ores located within the confines of a mine (that is, broken or fractured ore, stope fill, caved material, or ores in permeable zones) or ores located in dumps, prepared ore heaps, or tailing ponds. The term solution mining has, in general, been used to mean the in-place dissolution of water-soluble mineral salts with leach solutions. Chemical mining is presently in its embryonic stage. Basic research needs to be done to understand the influence of physical and chemical factors in chemical mining, and applied research needs to be done on both a small and a large scale to develop practical techniques of field practice. The areas of research include the following: (1) Leaching chemistry, the influence of physical, chemical, and biological factors in in-place leaching (2) Hydrodynamics of chemical mining systems (3) The development of new, as well as old, leaching agents for use under chemical mining leach conditions (4) The development of new means of contacting fine and coarse materials (with solutions) under static leach conditions (5) The development of new processes for generating and regenerating chemical mining leach solutions (6) The development of metal recovery processes

Jan 1, 1969

By Kenneth N. Han

The effect of anions such as sulfate, chloride, and nitrate on the solubility of rare earth element-bearing phosphates and fluorocarbonates has been examined using relevant thermodynamic data. The study has found that these anions have significant influences on the overall dissolution of rare earth elements (REEs) from various sources in the aqueous media. The thermodynamic calculations in this study have indicated that the speciation of REEs with the anions tends to increase the overall solubility of the REE-bearing minerals. However, in some cases, strong precipitation of REEs with some of these anions causes an adverse effect on the solubility of these elements. It has been found that sulfate ion has the most pronounced effect on the solubility compared to nitrate and chloride, in which the latter two acids exhibited almost identical results. The calculated results have indicated that REE-oxide (hydrated) is the easiest compound to dissolve, followed by carbonate, phosphate, fluoride, sulfate, fluoro-carbonate, and oxalate in that order.

By E. O. Mixon, Jack D. Kennedy

INTRODUCTION This contract is the most northerly portion of the Metropolitan Sanitary District of Greater Chicago's Tunnel and Reservoir Plan. (TARP) The project begins at Addison Street in Chicago and proceeds northerly approximately ten miles to end at Wilmette Harbor and Lake Michigan. The project which consists of 2 work shafts, 32 drop shafts, 7.322 km (24,020 ft.) of 6.7 m (22 ft.) diameter circular rock tunnel, 8.458 km (27,750 ft.) of 9.2 m (30 ft.) diameter circular rock tunnel and miscellaneous rock bolting and grouting, was bid for a total cost of $63,140,480. The tunnel invert elevation varies from 65.5 m (215 ft.) to 77.4 m (254 ft.) below the ground surface, which places the tunnel in a rock formation of dolomite limestone. At the tunnel invert, the unconfined compressive strength of the limestone varies from 96 MPa (14,000 psi) to 152 MPa (22,000 psi). The 6.7 (22 ft.) diameter tunnel required the mining of 10.9 cu m. (14.2 cu yd.) of rock per lineal foot of tunnel while the 9.2 m (30 ft.) diameter tunnel required the mining of 20.1 cu m (26.3 cu yd.) of rock per lineal foot of tunnel. The total cubic meters of rock required to be excavated from both tunnels was 818,821 cu m (1,070,978 cu yd.). All of this will be mined by tunnel boring machines (TBM). These tunnels were not to be lined with concrete. The thirty two drop shafts have upper portions that are cylindrical in the overburden and rock sections. They were divided into two groups, depending on diameter, with a different construction method for each group. The first group consisted of twenty three of the

Jan 1, 1979

By J. B. Hanlon

In order to protect coal mine owners, operators, and lending institutions from potential environmental liabilities, responsible parties must maintain a thorough understanding of the environmental disposition of the property they control, and the ramifications of impending laws and regulations. The best way to accomplish this is to periodically conduct a Phase I Environmental Audit. The systematic approach of an audit will reveal areas of DOD compliance with SMCRA and EPA regulations which the coal owner and/or operator will be able to use to correct deficiencies and prevent the occurrence of conditions which could lead to permit block, fines, and ultimately reduced productivity.

Jan 1, 1995

By Bill Dershowitz

Consider a deep gold orebody with grade of 4 g/t (0.11 oz/st). At the time of this writing, with gold prices at historic highs, it could be a good, but not great, prospect. But if it is a vein deposit, and those veins are 200 g/t (5.8 oz/st), it would be significantly more attractive if there was a way to produce directly from those veins, leaving the rest of the rock in place. [Figure 1 The red around each of the four injector wells shows areas of high pressure, where the lixiviant fluid is pumped into the rock mass, with orange and yellow indicating dissipated pressure. The black lines indicate some of the fracture pathways through which the lixiviant, with absorbed metal, flows toward the central recovery well where low pressure is indicated in blue. Lixiviant is pumped out through the recovery well. Image courtesy of Golder Associates.] There is a way to do this, in situ leach (ISL) or solution mining. It has been a viable commercial technology for more than five decades.

Jan 1, 2011

By L. J. Hoover

The objective of this study was to assess the health and environmental impacts of fluidized-bed combustion (FBC) of coal, specifically as applied to baseload generation of electrical energy by utilities. The study* was a short-term effort that based its analyses on information derived from the experience of the group or quickly obtained from the literature. The approach was to compare Atmospheric Fluidized-Bed Combustion (AFBC) and Pressurized Fluidized-Bed Combustion (PFBC) with two current technologies: low-sulfur coal combustion (LSC) and flue gas desulfurization (FGD) used with high-sulfur coals. A wet-limestone process was selected as the FGD technology. The impacts compared involved not only health and environment but also sociology, resource use, and dollar cost. Conditions for comparison were centered around a nominal date of 1988, when initial operation of commercial AFBC plants may occur. The PFBC has a later introductory date, a nominal 1995 (its impacts relative to other competitive technologies now in the R&D stages were not compared.)

Jan 1, 1978

By Jared Winkler, Jon A. Hummer, Aleksandar D. Bugarski, Shad Peters, Steven E. Mischler, Steve Cochrane, Shawn Vanderslice, Teresa Barone

The case study assessed submicron aerosols at a continuous miner (CM) section, diesel aerosol concentrations at the longwall (LW) section, and elemental carbon (EC) and total carbon (TC) exposures. Aerosols at CM sections were a mix of freshly generated and those from main drifts. Low ambient concentrations and personal exposures suggest effective control strategies, with further reductions possible by curbing emissions from high-emitting light-duty vehicles.

Mar 16, 2022

By Nathan Bowersox, Zuzana Skovajsova, David M. Jurich, Brian Harris

When unwatered after more than 50 years of operation, the White Rock Tunnel of the Upper American River Project in the foothills of the Sierra Mountains exhibited failing rockbolts and ground falls. Repairs designed for the 5 mile-long, 24-foot horseshoe unlined hydropower tunnel included pattern rock bolts, shotcrete, and cleanout of the rock trap. The work, originally scheduled for two 3-month winter outages, was completed under challenging conditions in a single 4-month outage following a carefully sequenced work plan using robotic shotcrete and rockbolter machines. Flexibility, creative solutions, and collaboration by all parties were key to project success.

Jun 13, 2021

By Samuel Frimpong

The preparation of graduate talent for the mining industry is a challenging process, given the multifaceted and complex array of decisions mining engineers make in discharging their responsibilities. As leaders, mining engineers must manage operations, lead project teams, mentor junior engineers, chart the technological directions of companies and deal with several organizations for maintaining the technical and economic feasibility of operations within strategic and tactical framework. Traditionally, the completion of the bachelor of science degree curriculum, with a minimum cumulative grade point average (CGPA), has been used as a graduation measure by Missouri University of Science and Technology (Missouri S&T). Companies have long realized the limitations of the CGPA for recruiting graduates because mining engineering is an applied engineering discipline. Company recruiters have sought to correct the limitations by factoring experience and behaviors into the selection process when recruiting knowledgeable and well-rounded graduates. In this paper, the authors introduce a new metric, which combines the current CGPA (knowledge) with experience and attribute (KEA) metrics to gauge the job readiness of graduating engineers. The KEA metric, also called the job-readiness factor (JRF), is the sum of K (50%), E (30%) and A (20%). The KEA process has been applied to a graduating class in Missouri S&T to demonstrate the value of the new metric system. The results show a fairly positive correlation between CGPA and the KEA metric, with a coefficient of determination of about 70%. Overall, the KEA metric system provides a better picture of the capacity and job readiness of graduates entering the workforce.

Jun 1, 2013

By Dan S. Nilsson

Small-scale mines are today expected to provide much of the increased production of metals, industnial minerals and coal this country demands in the future. But what is the size trend in the mining industry?

Jan 1, 1980

By Osamu Nishikokura, Jumpei Yamashita, Darrell Liebno, Malcolm Sheehan

"The Eglinton-Scarborough Crosstown Project builds a 19km LRT corridor that includes a 10km underground portion, between Keele Street and Laird Drive. The West Tunnel Contract (ECLC1-15) includes 6.5km of twin EPB TBM bored tunnels with a 5.75m internal diameter precast concrete segment lining (PCTL), between Keele Street and Yonge Street. This paper summarizes the overall scope of work, the technical challenges faced and innovative solutions developed by the contractor during the TBM move across an existing subway tunnel using state of the art high capacity strandjack gantry crane.1. PROJECT OVERVIEW The Greater Toronto and Hamilton Area (GTHA) is Canada’s largest urban region, populated with over 6 million people, and is one of the most rapidly growing regions in North America. One forecast estimates that the population of this region will increase to 8.6 million by the year 2031. In September 2008, Metrolinx, an agency of the Government of Ontario, launched a 25-year regional transportation plan named “The Big Move” to cope with the expected increase in transportation demand. The Eglinton-Scarborough Crosstown, one of the projects included in “The Big Move”, is a light rail transit (LRT) that will run across Toronto in an east-west direction between Mount Dennis and Kennedy along Eglinton Avenue. In October 2012, the West Tunnel Contract of the Crosstown LRT (ECLC1-15) was awarded to Crosstown Transit Constructors (CTC), a joint venture between Obayashi Canada Ltd., Kenny Construction Company, Kenaidan Contracting Ltd. and Technicore Underground Inc. The project includes approximately 6.2 km long twin bored tunnels, 9 cross passages, 1 emergency exit building, 7 sets of station headwalls, and an intermediate pair of extraction and launch shafts. Each of 6.5 km long twin tunnels are divided by the existing subway station into two drives: the first half from the launch shaft LS-1 (west of Keele Station) to the extraction shaft ES-1 (west of Eglinton West Station), and the second half from the launch shaft LS-2 (east of Eglinton West Station) to Yonge Station, as shown in Figure-1. The TBMs are extracted at ES-1 and moved to LS-2 over the existing Yonge-University Subway Line at Eglinton West Station before resumption of tunneling at LS-2."

Jan 1, 2016

By C. S. Todd, R. L. McNearny, S. Dun, P. Clark, P. W. Conrad, X. Liu, J. Q. Wu, H. Rhee, W. J. Elliot

Soil erosion is strongly related to soil hydraulic properties. Understanding how surface coal mining affects these properties is therefore important in developing effective management practices to control erosion during reclamation. To determine the impact of mining activities on soil hydraulic properties, soils from undisturbed areas, areas of roughly graded mine spoil, areas with replaced topsoil before seeding, and revegetated areas at the Rosebud Mine in Eastern Montana were evaluated. Field and laboratory studies were conducted to determine the soil hydraulic properties of the four representative areas, including particle-size distribution, organic matter content and saturated hydraulic conductivity. Using this data, Water Erosion Prediction Project (WEPP) simulations and risk analyses were performed to investigate mining’s effects on changes in soil erosion potential. Significant differences were seen in the hydraulic properties of the soils in the representative areas due to the mining and reclamation practices at the mine. The WEPP simulations show that the potential for soil erosion increases as a result of mining activities disturbing the soil. The simulations also indicate that the erosion potential may return to pre-mining levels over time with effective revegetation practices.

Jan 1, 2015

What is your personal view and assessment of the overall health of the industry in the current global economy? The economic outlook remains soft for the near future and, although the global economy is showing signs of recovery, uncertainty has tempered the pace of recovery. In addition to uncertainty, we are still facing significant economic challenges in many parts of the world, including Europe and the United States. The rapid expansion of China?s economy has recently slowed, further contributing to the sense of uncertainty in the overall health of the global economy. This situation is both a blessing and a curse, depending on which sector of the mining industry we are considering. For example, coal, industrial minerals, aggregates, base metal and precious metals markets are impacted by different forces and drivers and will experience different outcomes within the same economic environment. Let me give a few concrete examples to illustrate this concept. The prevailing economic uncertainty that I have just described tends to drive investors toward safe havens. Gold has historically been viewed as a safe haven and as long as investors shy away from traditional investments, gold prices will remain high and gold mining companies will continue to expand and invest capital in their operations. The same sluggish economy that drives gold prices higher has the opposite effect on other segments of the minerals industry. A great example of this is industrial minerals and aggregates used in construction. The markets that consume these minerals have contracted significantly over the past five years. The outlook for this segment is poor, as the glut of available housing continues to inhibit demand for new construction and, thus, many industrial minerals. In addition to this, the federal government?s lack of political will to enact long-term legislation funding transportation and infrastructure projects continues to be a drag on the U.S. aggregates industry.

Jan 1, 2013

By K. Biswas

For the pillars, which have been standing long after mining, the stability depends much on the weathering action in the presence of mine moisture. From the field observations, it has been found that this weathering action becomes critical in terms of pillar stability if the coal seam contains partings or binders in it. The weathering action degrades both the partings and coal in terms of their load bearing capacity as the mine moisture penetrates into them. This paper investigates the effect of weathering action on coal and partings in the laboratory. In the field, the strength profile in the coal and the partings and the effect of time (in terms of the pillar age) on them have been studied by using borehole penetrometer. In this paper, an attempt has also been made to establish formulae for time dependent strength of coal and partings.

Jan 1, 1997