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By Igor Gonzales G.

The Southern Peru Copper Corp. (SPCC) recently built an integrated copper project consisting of dump- and heap-leaching operations at its mine complex in Peru. The pregnant leach solution (PLS) containing the solubilized copper from the leaching operations is processed in a new solvent extraction/electrowinning (SX/EW) facility to produce high-purity cathode copper. The dump leaching and SX/EW facilities are located near the Toquepala mine site. The crushing and heap-leaching operation is located at the Cuajone Mine. The pregnant leach solution from Toquepala and Cuajone is pumped 35 km (22 miles) to the SX/EW plant at Toquepala. The SX/EW plant consists of three trains of solvent extraction (SX), a tank farm area and an electrowinning (EW) facility. The solvent extraction plant has a total PLS flow capacity of 3,210 m3/hr (113,360 cu ft/hr). The electrowinning facility has an expected long-term production capacity of 97 t/d(107 stpd) or about 35 kt/a (38,500 stpy) of cathode copper. However, present production exceeds the expected long-term by about 20%.

Jan 1, 1996

By S. Lolon

Spontaneous combustion in underground coal mines has become a serious problem particularly in the caved area (gob). Recent statistic has shown that approximately 17% of total 87 underground coal mine fires in the United States are attributed to spontaneous combustion (De Rosa, 2004). Spontaneous combustion results from a self-heating process in exothermic conditions. The accumulated heat, if not removed, is conducive to the rapid increase of temperature and may result in mine fires or explosions. It is well accepted that the interaction between oxygen and coal substances is the main cause for spontaneous combustion, while other factors such as pyrite, moisture, and bacteria play a secondary role to the self-heating of coal. Therefore, only coal oxidation is considered in this study. Coal oxidation occurs as coal comes into contact with air. This process involves complex phenomena in terms of heat transfer, chemical surface absorption, and energy balance related to inherent properties of coal (Wang et al., 2003). For simulation purpose, overall reactions can be simplified as suggested by Mitchell (1990): C + O2 CO2 + heat [65°- 94°C] (1) CO2 + C 2CO + heat [100°- 150°C] (2) Stoichiometric reactions (1) and (2) show that 2.66 grams of oxygen are required to oxidize 1.0 gram of carbon. Once the temperature exceeds 100°C, the reaction has little chance to stop. The crucial step in reducing spontaneous combustion risk is locating the ignition point of spontaneous combustion (hot spot). This information is useful in the effort of developing a preventive method effectively. In this study, this was conducted based on the best gathered information: ventilation surveys conducted in an existing longwall mine located in the western US; the laboratory experiments performed on a physical gob model; and the CFD models to investigate the flow behavior in the gob, the oxidation of coal, and heat transfer phenomena. The hot spot location is determined as a function of oxygen concentration and gob temperature. The critical values are the following: 5% (by volume) for oxygen and 100°C for gob temperature. CHARACTERISTICS OF GOB MATERIAL AND MODELS Permeability Concept Permeability is one of the key parameters in any study dealing with porous medium. This is determined by particle size and the ratio of void volume to the total volume (porosity) of porous medium. This relationship is known as the Carman-Kozeny equation (Scheidegger, 1957) and is given mathematically as [ ] where k* = theoretical specific permeability, m2 dm = the mean particle size, m n = porosity However, permeability tests with various particle sizes were carried out at the University of Utah?s ventilation model (Figure 1) to verify this relationship. These tests indicated a necessity to modify this theoretical relationship. A factor of 0.898 was obtained to make up the different between theoretical permeability and the experimental one. The modified version of (3) is given by: [ ] This equation is used to determine permeability of the simulated mine gob throughout the study. [ ] Mine Gob Material The gob is represented by zones filled with material of given size distribution. For physical measurements and CFD simulations, the material used were crushed rock and coal. Due to compaction, three different characteristics of gob material were used in the model: unconsolidated, semiconsolidated, and consolidated. In the real condition, the largest coal-rock particles are more likely to be located in the area behind the shields. This material is freshly broken and unconsolidated. The size of these broken particles is based on a study carried out by analyzing images taken from the area behind the shields in three coal mines in the United States (Pappas and Mark, 1993). The results have shown that the mean size of materials behind the shields is about 1.22 m. The permeability associated with this size was then obtained from (4) and permeability tests. This was 4.68 x10-7 m2. For semiconsolidated and consolidated zones, due to the lack of experimental data, these were determined through CFD simulations. These simulations were designed by assigning a permeability of 3.15 x 10-8 m2 for consolidated zone and 7.98 x 10-9 m2 to the other zone. The airflow pattern in the gob assigned with given permeabilities was expected to follow the experimental distribution (Brunner, 1985). The mean particle sizes for the semi-consolidated and consolidated zones were 0.02 and 0.006 m, respectively; smaller than those of the unconsolidated zone. Figure 2 shows the 3D view of permeability changes in the gob.

Jan 1, 2009

The National Mining Hall of Fame will induct five mining greats on Saturday, Sept. 17, 2005 at the Museum Convention Center in Leadville, CO. The 18thAnnual National Mining Museum and Hall of Fame Induction Banquet will begin with an open house and reception at 5:30 p.m., followed by the dinner and program at 7 p.m. The five inductees are Nathaniel Peter Hill, John Munro Longyear, John McDonald, Julius Eckhardt Raht and John Dennis Ryan. Nathaniel Peter Hill (1832-1900) built the first successful smelting operation in the Rocky Mountains in1867 at Black Hawk, CO. From 1879 to 1885, he was a U.S. senator. He also taught courses at the Colorado School of Mines.

Jan 1, 2005

By M. William Lallman

Potash production from natural brines of the Bonneville Salt Flats has a comparatively long history dating back to the start of World War I. However, it vas sot until the late 1930's that a successful commercial potash operation was achieved by a firm known as Bonneville Ltd. While improvements in operating techniques, pond design and equipment have been incorporated as they became available it should he understood that the basic technology developed in the late 30's and early 1940's by Bonneville Ltd, for potash production has not been changed significantly. The purpose of this paper is to present a brief review of the history, geology and hydrology of the Bonneville Potash operations and discuss the cur¬rent methods employed for brine collection, solar evaporation and the recovery of potash and other brine chemicals. A detailed study of the hydrogeology of the Bonneville Salt Flats wan made by L. J. Turk,1 Ph.D. thesis for Stanford University in 1969, under the auspices, of Kaiser Chemicals the Industrial Chemicals Division of Kaiser Aluminum & Chemical Corporation. Turk's thesis furnished much of the information presented in this paper.

Jan 1, 1976

By J. H. Mackey

"Where can I obtain a reclamation bond today?" "Who is writing your bonds?" These questions are common and heard frequently. The fact that the Society of Mining Engineers has determined that two of the five environmental topics reviewed at the 1989 Annual Meeting relate to reclamation bonding indicates to me that those who are involved in the coal industry, no matter what capacity, remain very cognizant of the reclamation bonding dilemma.

Jan 1, 1989

By Michael Edesess

The salt gradient solar pond has been the focal point of accelerating international attention and interest in recent months. Only recently have most investigators in the renewable energy field come to realize the versatility of the solar pond, and its ability to overcome certain problems usually associated with solar technologies. These realizations, together with clear demonstrations in Israel and elsewhere of its technical feasibility, have combined to bring the solar pond to the forefront of renewable energy technologies. The solar pond is a natural or site-built pond, about one to five meters or more in depth, which has been altered to retard the loss of absorbed solar energy. The absorbed solar energy is usually lost through upward buoyancy of the warmed water, followed by the loss of its heat to the atmosphere. The chief solar pond technology -the salt gradient, or "nonconvective" solar pond-prevents this upward buoyancy by means of a vertical density gradient achieved with dissolved salt. The deep waters in the solar pond reach high temperatures, up to and even above the boiling point of pure water.

Jan 1, 1981

By Roozbeh Afzali

Designing an appropriate tunnel blasting pattern reduces the cost of rock breakage and subsequent operations such as loading, haulage and support of tunnels. For that reason, we developed a software that designs tunnel blasting patterns. Using this software, three different tunnel blast design models based on parallel hole cut, namely, Swedish, Konya and Energy Balance, were investigated and compared for a virtual tunnel. Accordingly, blasting patterns were designed, for different cross sections. The trend of parameters such as specific charge and specific drilling as functions of tunnel cross-section was determined for each model. Our results show that, in general, The Swedish model gives lower specific charge and specific drilling compared to other models.

Jan 1, 2008

By T. Weatherwax

As part of a strategic research initiative at UBC to design and evaluate integrated underground mining and mineral processing systems, work has been done to determine how to utilize the coarse rejects of pre-concentration in the underground environment. An amenability study for nine orebodies from four of Xstrata Nickel?s Ontario operations evaluated both processing and waste disposal methods. The utilization of the rejects as a high quality backfill with minimal binder requirements has been identified as the preferred disposal method. Fill mixes utilizing the rejects in combination with classified tailings, full tailings, and cement were developed based on the geotechnical properties of the rejects. The mix designs were examined for both strength and rheological properties. The paper will present the results of the pre-concentration testwork, the design and strength testing of various mix designs for rejects from the nine ores and presents a conceptual design for an underground pre-concentration system based on this test work.

Jan 1, 2008

By David Caiden, Geoffrey Fosbrook, Jaidev Sankar, Donald Phillips, Jon Hurt, Anil Parikh

This paper will cover the progress being made on Phase 1 of New York’s Second Avenue Subway line. It will include a description of construction progress on the first contract to be let, which consists of a 248 m (815 ft) long launch box, 3.9 km(2.4 miles) of TBM tunnels and a tunnel sump; the packaging strategy for the remaining work; and the progress through Final Design of the remaining packages, including the two large span rock cavern stations.

Jan 1, 2007

By P. A. Dimas

A new family of sulfide flotation collectors has been developed in our laboratory. These formulations are comprised of novel renewable materials combined with conventional reagents. The resulting diversity permits tunability of collector chemistry to meet a range of flotation problems. Several attributes of the new collectors are presented.

Jan 1, 2012

By Vojtech Gall

Pre-support measures for urban tunneling have seen a substantial development in the recent past. Ground improvement techniques, pipe-arch and spiling methods now allow for non-disruptive tunneling at very shallow depths under sensitive structures, rail tracks and roadways. The paper presents experience gained on national and international projects built over the past decade that represent case histories and therefore may be used as guidance for the development of similar solutions for future tunneling projects at shallow depths. Reference projects include tunnels for the Washington, DC Metro, London Underground, Dulles Inter-national Airport, Busway tunnels in Boston and the Ft. Canning Tunnel in Singapore.

Jan 1, 2008

By Steve Kral

MINExpo INTERNATIONL 2000 was a good place for companies to introduce new products, technologies and services to the mining industry. Caterpillar took that a step further. The company hosted a one-day preview of its mining products at its Tinaja Hills Training and Demonstration Center near Tucson, AZ. About 30 members of the trade press spent the day at Tinaja Hills before heading on to Las Vegas for MINExpo INTERNATIONAL 2000. Dozens of Caterpillar professionals provided the editors with a first-hand look at Caterpillar’s mining trucks, loaders, excavators, road graders, water trucks and engines. In addition, these Cat experts explained the intricacies of each piece of equipment, the latest technology that led their improvement and their value to the company’s mining customers.

Jan 1, 2000

By A. B. Cecala

Video technology coupled with data logging exposure monitors have been used to evaluate worker exposure to different types of contaminants. However, previous application of this technology used a stationary video camera to record the worker?s activity while the worker wore some type of contaminant monitor. These techniques are not applicable to mobile workers in the mining industry because of their need to move around the operation while performing their duties and tasks. The Helmet-CAM is a recently developed exposure assessment tool that integrates a person-wearable video recorder with a data logging dust monitor that are worn by a miner in a backpack, safety belt, or safety vest to identify areas or job tasks of elevated exposure. After a miner performs his or her job while wearing the unit, the video and dust exposure data files are downloaded to a computer and then merged together through a NIOSH-developed computer software program called EVADE (Enhanced Video Analysis of Dust Exposure). By providing synchronized playback of the merged video footage and dust exposure data, the EVADE software allows for the assessment and identification of key work areas and processes, as well as work tasks that significantly impact a worker?s personal respirable dust exposure. The Helmet-CAM technology has been tested at a number of metal/nonmetal mining operations and has proven to be a very valuable assessment tool. Mining companies wishing to use this technique can purchase a commercially available video camera and an instantaneous dust monitor to obtain the necessary data, and the NIOSH-developed EVADE software will be available for download at no cost on the NIOSH website.

Feb 27, 2013

By I. Ocak

Initial investment for mechanical boring of tunnels is found to be high in most cases. Conventional drilling and blasting is not the possible especially in urban area. In these conditions impact hammer offers many advantages over conventional drill and blast techniques and boring tunnels. These include improved safety, minimal ground disturbances, elimination of blast vibration, reduced ventilation requirements, reduced cost etc. Therefore, hydraulic impact hammers have been used widely in metro tunnelling projects in Istanbul since 1992. Accumulated and published data from various tunnelling projects serve to improve predicting the machine performance and scheduling of job duration. This paper is prepared under this objective. Machine utilization time of impact hammer was evaluated in this study. The main rock formation named Kartal formation arepaleozoic aged sedimentary rocks, shale, sandstone, siltstone, andesite dykes and sediment fillings. The first stage of the project is commissioned to Yapi Merkezi- Yuksel- Dogus- Yenigun- Belen consortium.

Jan 1, 2011

By Kenneth L. Maloney

Ten small and intermediate-sized [11 GJ/hr to 264 GJ/hr (10,000 lb/hr steam to 250,000 lb/hr steam)] coal-fired boilers in the upper Midwest have each been tested on both a bituminous eastern coal and a subbituminous western coal. The purpose of this study was to determine the feasibility of substituting western subbituminous coal for eastern bituminous coal as a means of reducing the SO x emissions from this class of boiler and to demonstrate the feasibility of greatly expanded western coal utilization as a means of reducing the use of oil and gas. The scope of this study was such that the representative boiler types were tested on both eastern and western coal for a period of time sufficient to completely characterize their individual emission and operational characteristics.

Jan 1, 1977

By C. S. Compton, T. E. Marshall, D. R. Dolinar, R. Grau, L. J. Prosser, A. T. Iannacchione, D. C. Oyler

Unrecognized roof beam failures resulted in 69% of the falls of ground injuries occurring in underground U.S. stone mines from 1990 to 1996. Field investigations at 45 underground stone mines suggest that excessive beam sag or deflection is the principal unstable roof behavior characteristics associated with miner injuries. Laminated roof structures, common in most underground stone mines, allow the immediate roof to separate into distinct beams. The timely determination of roof beam deflection could provide stone miners with advanced knowledge of potentially hazardous roof. Existing methods to assess roof conditions consist of observational and monitoring techniques. Observational techniques include open drillholes, sounding, wedging, and borescopes. Monitoring techniques include scratch tools, extensometers, telltales, Miners Helpers, and Guardian Angels1. Miners have difficulty utilizing these techniques because roof beams are located an average of 8 m(26.5 ft) above the miner’s head in environments that are dark, dusty and noisy and these deflections are measured in millimeters of movement. To help mitigate the potential for falls of ground injuries to underground stone miners, the National Institute for Occupational Safety and Health (NIOSH) has developed the Roof Monitoring Safety System (RMSS) to aid in monitoring dangerous levels of roof beam deflection. If enough site-specific information is collected and placed on highly visible maps, individual mining operations could establish general guidelines for responding to specific roofbeam deflection occurrences. This would help in implementing a pro-active, comprehensive roof control plan for reducing falls of ground injuries.

Jan 1, 1999

By M. Pope

By 1950, packaged oil and gas fired boilers were on the market for capacities up to 30,000 lbs./hr. By 1962, capacities were up to 100,000 lbs./hr. and even higher when separate heat traps (economizers and air preheaters) were attached to the boiler packages. During this period, complete packaged coal fired boilers were developed into the 10-15,000 lbs./hr. range. Oil and gas fired plant designs became very compact, "basementless", and far: less costly than the coal fired plants of any capacity. Coal fired plants remained large and expensive, required field erection of boilers and required basements. With the spectacular strides made in automation, oil and gas plants became far less costly to operate, requiring only the part-time attendance of a single operator. Some advances were made in coal fired plants, but not to the degree attained by the fluid fuel competition.

Jan 1, 1965

By L. B. Hales

Expert control of grinding and flotation plants has been successfully used in the minerals industry since the 1970?s. The earliest of these systems were written in a hard-coded fashion in FORTRAN, BASIC or Pascal. Second generation systems were built using the first experimental expert system shells that were being developed in the artificial intelligence community. Later systems were deployed in expert system shells designed for real-time processing plants that also included the ability to model the process with neural network models and optimize setpoint selection through the use of genetic algorithms. Significant performance increases have been achieved using these systems, but in general, they suffer from the static nature of their rules and to a degree the process models also. Typical improvements quoted in the literature suggest throughput rate increases of 4 to 8 percent and recovery increases of 1 to 4 percentage points. In over 30 years of designing and installing expert systems we have never seen performance numbers less that these but have often seen numbers in excess of the high values. However, once the system has been installed and tuned up the performance usually does not improve much thereafter. Granted, the initial increases in throughput rate and recovery are significant but a question always lingers, that is, can the expert strategies be modified further to squeeze a little more improvement out of the system. The answer to this question is a resounding yes, however a complete understanding of what we do well as designers and operators of expert control systems is required as well as how we can improve upon our best practices is required to move us from the performance plateau we have been on for a number of years to a new higher level of performance.

Jan 1, 2009

By L. E. Beverage

In 2006, the Mine Improvement and New Emergency Response Act (?2006 MINER Act?), Pub. L. No. 109-236, 120 Stat. 493 (2006) was enacted in a bi-partisan move to strengthen the 1977 Mine Safety and Health Act. This action followed several underground coal mining accidents at the Sago and Aracoma Mines in West Virginia and the Darby Mine in Kentucky. The focus of that legislation was, in part, to force technological development and implementation. It involved the recomposition and training of rescue teams. Requirements for sealing worked out areas of mines were changed when MSHA invoked its Emergency Temporary Standard (?ETS?) authority for the first time in many years. Increased penalty amounts were established for certain types of violations for all types of mining, and minimums were set for unwarrantable failure violations issued under Section 104 (d)(1) and (d)(2); 30 U.S.C. Section 814 (d)(1),(2). The entire 30 C.F.R. Part 100 penalty criteria was revamped in a rulemaking, effective in April 2007. The visions were ambitious and noteworthy and those in industry and government have spent the last four years working through the aftermath of intended and unintended consequences of these changes. The penalty structure arrived at in 2007 has proven unwieldy and has contributed to the increase in contested caseload now before the Federal Mine Safety and Health Review Commission. In essence, litigation under the Mine Act ground to a virtual halt when the number of cases increased but the budget for Administrative Law Judges, who hear the cases, and the Solicitor?s office who represents MSHA, was not increased. Addressing the backlog effectively was one of the major challenges when Joe Main was confirmed as Assistant Secretary in early 2010.

Jan 1, 2011

By Tae-kyeong Yeu, Jong-Choi, Cheon-Hong Min, Hyung-woo Kim, Jae- Won Oh, Sup Hong, Minuk Lee, Sung-Soon Kim, Chang-Ho Lee, Ki-Young Seong

"Collecting mineral resources from the seabed using a seafloor crawling robot is the firststep in the mining operation. The second-step is lifting the collected ore up to the water surface. For lifting through a riser pipe, prevention of pipe clogging (flow assurance) and economic and eco-friendly up-transferring is of the utmost concern.During collection of mineral ores, the production rate can be highly variable because of the variability in the distribution of the mineral deposit, variations in seafloor topography, fluctuations robot speed, and variations in performance of the mining robot, etc. Direct transfer of the collected ore to the riser pipe might cause unpredictable and serious problems such as over-loading of the lift pump, reduction in the life of the equipment, pipe clogging, severe increase of down-time, critical damage of equipment, further propagation of damages, and total failure after all.As a counter measure to these potential problems, a buffer station has been adopted, which is capable of storing the collected ore for a certain time and simultaneously regulating the transfer of the ore into the riser pipe. A pilot buffer has been developed by KRISO/KIOST (see Fig. 1)."

Sep 1, 2014