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By J. F. T. Agapito

Experience at Energy West Mines in the Wasatch Plateau Coal Field, Utah, has shown that longwall face bursts occur mostly near the tailgate when extracting the third adjacent longwall in a panel section where depths exceed 610 m (2000 ft). It is believed that this is due to a combination of cover depth and side abutment stresses created by the widening of a pressure arch formed by interlocking and bridging of large blocks of" very competent strata. The 60-m-thick (200 ft) Castlegate Sandstone probably plays a key role in pressure arching. This paper presents a back-analysis of the location and magnitude of the stresses associated with face bursts that occurred when mining the 7th Right Longwall at the Deer Creek Mine. Improvement of these conditions may be achieved by widening the longwalls to attain critical subsidence width sooner while mining the second long-wall, and to reduce stresses at the face. Wider longwall faces, however, increase the chance of sandstone channel interception often associated with bursts. Satisfactory mitigation of face bursts beyond cover depths of 610 to 670 m (2000 to 2200 ft) may be difficult without using destressing techniques. The hydraulic fracturing/liquid infusion technique seems to offer the best possibilities for application in longwall mining.

Jan 1, 1997

By G. Davis

It is well known that the anticipated mineral price at the start of a prospective mineral project can have an overwhelming effect on a property's ex ante value. However, possible price movements throughout the life of a project can also have an impact on this value. This paper demonstrates how different potential price paths can affect project value. When considering commodity price projections for mine valuations, it is thus necessary to estimate not only the expected commodity price at the start of the project, but also the manner in which that price is likely to fluctuate throughout the project's life.

Jan 1, 1995

By Thomas M. Lynberg

WIDCO is a surface coal mine located near Centralia, Washington. The WIDCO preparation plant processes over 7 million tons of run- of-mine coal each year with a product yield averaging 72%. In the jig type preparation plant the fine refuse amounts to approximately 130 dry tons per hour of 28mesh by 0. This fine refuse material is thickened in a 160ft. diameter static thickener with the use of lime as a coagulant and organic polymer as a flocculant. Once thickened the fine refuse, which is predominately bentonitic clays, has been dewatered and disposed of using several different methods. These methods will be discussed and include vacuum disc filters, ponds, solid bowl centrifuges, belt filter presses and experiments with electrokinetic dewatering.

Jan 1, 1981

By A. G. Mayton, D. H. Ambrose, C. C. Jobes, N. K. Kittusamy

In a systematic study, the National Institute for Occupational Safety and Health (NIOSH) evaluated seat designs in low- and mid-seam shuttle cars during production operations at two underground coal mines in southern West Virginia. The purpose was to support, with additional data, earlier findings that NIOSH ergonomic seat designs (featuring viscoelastic foam padding and lower-back support) may help reduce health risks to operators of coal mine shuttle cars. Eight shuttle car operators evaluated seven seat designs (one already in use in each vehicle and five NIOSH designs) relative to perceived and measured whole-body vibration (WBV) exposure (including vehicle jarring/jolting) and discomfort. Operators’ perceptions using a visual analog scale (VAS) and questionnaire ratings were compared with International Standards Organization (ISO) 2631-1:1985 fatigue-decreased proficiency (FDP) limits and measured WBV levels on low- and mid-seam shuttle cars. Objective and subjective data results indicated that NIOSH seat designs (with added adjustability, lower-back support and improved seat padding) performed better to reduce vehicle jarring/jolting levels and that shuttle car operators favored them over existing seat designs. The NIOSH low- and mid-seam shuttle car seats showed 45 to 77 percent better performance in FDP and 9 to 60 percent better performance overall in operators’ ratings. Considering the VAS results for low- and mid-seam shuttle cars under no-load conditions, operators rated the level of jarring/jolting 18 to 89 percent lower with the NIOSH seats. Reductions in measured vehicle jarring/jolting were 19 to 46 percent for the three-directional vector sum accelerations relative to the existing seats on the low- and mid-seam shuttle cars. Questionnaire responses indicated that operators for both shuttle car models rated NIOSH seat designs as more comfortable overall. Vehicle operators most frequently suggested adding armrests to improve the seats on the mid-seam shuttle car. A suggested improvement for the low-seam shuttle car was to make the seat a better fit for the operator compartment, which would enhance clearance between the operator and vehicle controls and allow for better seat adjustment and operator visibility.

Jan 1, 2009

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

This paper reports on the behavior of mercury and its compounds during the thiosulfate leaching and recovery of gold. Thiosulfate solutions are shown to dissolve Hg0 and Hg2Cl2 to a similar extent as cyanide, but the leaching of HgS is significantly slower in thiosulfate solutions compared to cyanide. Hence, the use of thiosulfate may be an option for treating ores containing high levels of cinnabar, especially since the legislation concerning the discharge or sale of mercury is becoming more restrictive. The deportment of mercury during gold thiosulfate loading and recovery using a strongly basic anion-exchange resin was also studied. Although the mercury thiosulfate complex loads on the resin, the adsorption is weaker than for gold, with an equilibrium constant between gold and mercury of 51. Resin loaded with gold, mercury and copper was pre-eluted with thiosulfate (to remove copper) and eluted with a chloride and sulfite eluant. The majority of the mercury is eluted by the eluant and, hence, its deportment closely follows gold and the eluate would need to be treated to remove either mercury dur-ing or prior to gold electrowinning.

Jan 1, 2010

By M. N. Chandraprabha

This paper discusses the role of the mineral-adapted acidiphilic microorganism Acidithiobacillus ferrooxidans in the beneficiation of arsenopyrite-containing multisulfides (pyrite and chalcopyrite) and the bioremediation of the resulting arsenical waste water. It was found that adaptation to minerals alters the surface properties of the microorganism. Bacterial adaptation to arsenopyrite and controlled bacterial adhesion to mineral surfaces lead to selectivity in arsenopyrite separation. Bioremoval of arsenic ions (both arsenite and arsenate ions) by Acidithiobacillus ferrooxidans is also discussed. Key words: Acidithiobacillus ferrooxidans, Bioremediation, Arsenopyrite beneficiation

Jan 1, 2009

By A. H. Reitsema, Hans E. van Dam

In CIP, CIL, and Heap Leach gold recovery operations, a sub-optimal activated carbon performance invariably causes a significant loss of revenues. In this paper it is shown, how dedicated analyses of carbon samples can be used as a guide in plant performance optimiza­tion. Firstly, a brief outline is given of the most important methods of analyses, including the specialized methods not normally used by mining operations, but provided by carbon manufacturers. Then, a number of practical cases are discussed in which carbon sample analyses provided insight which allowed significant improvements.

Jan 1, 1995

By Sean Dessureault

The ubiquity of big data, internet of things (IoT), and smart devices is radically changing society; our personal lives are being tracked, digitally motivated through gamification, where information has become an addiction at all income levels, genders, and generations. These forces should not be held at bay in mining; rather, we should embrace and take advantage of this phenomenon to improve safety and productivity. It is time to rethink long-held conventions behind Fleet Management Systems, such as permanently mounted hardware, connecting through cables and Bblack boxes^, equipment centric rather than operator-centric, wireless requirements, minimal to no feedback to the operator, and high costs. We should also reconsider how we are collecting much of our safety, training, and preoperational forms on paper that then, must be entered into computer systems for compliance, and rarely if ever used in analytics, rather than entering the data directly into a digital device. Collecting safety and location data directly digitally also unlocks the information contained in safety forms and audits enabling new data mining and analytical approaches. Managing then gaining value from this new, greatly expanded mountain of largely unstructured data, requires the use of modern tools and approaches, such as gamification and big data, as well as skill sets, not traditionally available in mines. Furthermore, tablets can now provide a better user experience as well as new sensors when compared with traditional fleet management systems (Mining Magazine 2019, 2016, 2015), at a fraction of the cost, employing the extremely esthetic and engaging visuals derived from the video game industry. Real case studies of these applications of both technology and approach, such as gamification, show that these tracking technologies can bring high visibility and large amounts of data to even the smallest operations and the challenge of making use of the data can be facilitated through the application of gamification. As with our personal smart devices, these technologies are poised to deliver huge improvements in operator feedback, tracking, and performance management, at a much lower cost per unit.

By Errol L. Montgomery

The region of metalic ore deposits in northern Chile, southern Peru, western Bolivia, and northwestern Argentina occurs in arid zones at altitudes as high as 4,600 meters. Because surface water supplies are meager, new mines require unexploited sources of water. Prolific groundwater aquifers occur in salar basins in this region of the Andean Highlands. Exploration water wells have been constructed and aquifer characteristics have been tested in eight salar basins. Results indicate groundwater quality is good. Aquifer transmissivity and storage computed from results of pumping tests indicate maximum production water well capacities in excess of 170 liters per second.

Jan 1, 1982

By Nick Karlin

Dragados USA is constructing the LA Effluent Outfall Tunnel, a 7-mile, 18 ft internal diameter effluent discharge tunnel, utilizing a 21.6 ft (6.585 m) Herrenknecht Mixshield TBM. This paper highlights the means and methods used for TBM launch from a 55 ft diameter shaft excavated in wet with diaphragm wall support of excavation. This included SEM excavation of jet grout blocks for starter and tail tunnels, temporary concrete structures and steel installations, TBM sealing system, umbilical management for TBM hydraulic, electric and bentonite circuits as well as complex segment delivery logistics. The many launching challenges were overcome thanks to the innovative approaches from the project team.

Jun 13, 2023

By T. Ritzel

Predictive maintenance technologies including vibration analysis, tribology, infrared thermography, ultrasonic detection, and electrical measurements have been applied to large electric mining shovels at Cyprus Sierrita. The predictive program was initiated by Cyprus Sierrita and P&H Mining Equipment at the Cyprus Sierrita Mine in Tucson, Arizona during August of 1996 on the P&H model 2300 and 4100 electric shovels. The utilization of these technologies has shown the potential for improving electric mining shovel availability and minimizing maintenance costs. Predictive technologies provide the tools to assess machinery condition. Availability is enhanced by the condition based planning of component replacement. Maintenance costs are minimized by focusing resources through condition based prioritization.

Jan 1, 1997

By M. S. Celik

The principal impurities in some feldspar ores are titanium and iron which impart color and in turn degrade the quality of the ore. The mineralogical investigations indicate that titanium element originates from mainly rutile with small amounts of sphene. Conventionally, fatty acids and particularly sodium oleate are extensively used in the flotation of colored minerals from feldspar ores with reasonable success. In this study, new reagents, oleoyl sarcosine and hydroxamate have been used to float colored impurities before and after magnetic separation. Oleoyl sarcosine is found to exhibit better results compared to fatty acids and hydroxamate. The mechanism of the action is elaborated on the basis of experimental data.

Jan 1, 1999

By M. A. S. Martins, J. C. Guillaneau

Steady-state simulation has been proving its usefulness and efficiency in process design and optimization for many years. Steady-state simulation is a very effective approach for plant design since it enables a great number of hypotheses to be considered regarding flowsheet, equipment etc., the processing equipment and material handling equipment to be sized, and the configuration of almost optimal industrial plant to be attained in a very short time. This paper will present the basic principles of mineral process simulation methodology and some real case applications of their capabilities in several complex ores in Brazil.

Jan 1, 1998

By C. L. Lin

The image-based On-line Particle Size Analyzer (OPSA) system has been developed at the University of Utah to measure particle size distributions under plant conditions where overlapped and segregated particles are being transported on a moving belt conveyor. Evaluation of the OPSA system at several plant sites has been completed. The results show a consistent agreement between the particle size distributions obtained from the OPSA system and those obtained from laboratory screen analysis of belt samples. These results and the stable performance of the OPSA system during the field tests suggest that continuous quality control of crushed products is possible using the OPSA system.

Jan 1, 1999

By Russell L. Cook

Stringent environmental regulations, which have limited the use of sludge ponds, coupled with the economic incentive to clean more 'coal or to add fine coal cleaning additions to existing preparation plants have increased the use of static thickeners in preparation plants. The Lamella Gravity Settler, sometimes de signated Lamella Thickener, is a shallow depth sedimentation device which has been applied in a variety of industrial process and wastewater control projects in place of the conventional raked thickeners. This paper presents the theory and design of the La-mella Thickener, as well as describing the operating results from several full scale installations in a variety of Appalachian preparation plants.

Jan 1, 1977

By G. P. White, J. M. Jones

Computer simtiation is a technique that has beers around for many years. Its applications include designing steel mills, planning space shota, or even developing ways to beat the casinos in Las Vegas. However, the use of computer sirndation in surface coal mining is fairly recent. To promote its use, several government agencies, including the US Bureau of Mines, Forest Service, and Department of Energy, contracted with universities and private companies to develop computer simulation programs for surface coal mining. Some of these developers include McDonnell-Douglas Electronics Co., Pennsylvania State University, Montana State University, Fluor Mining and

Jan 9, 1984

By James R. Arnold, Cindy S. Jones, Michael F. Gleason, John O. Marsden, John G. Mansanti

INTRODUCTION The Chimney Creek Gold Mine (Gold Fields Operating Co. - Chimney Creek) is located 47 miles northeast of Winnemucca, Nevada, at the northern end of the Osgood Mountains. The operation is a wholly owned subsidiary of Gold Fields Mining Corporation, the North American branch of Consolidated Gold Fields PLC, London, England. The plant started up in November, 1987, less than three years after discovery of the orebody and three months ahead of schedule. Ore is mined in an open pit and is processed by combined dump leaching and milling techniques for gold and silver recovery. The mine is set to produce approximately 150.000 ounces of gold and 50,000 ounces of silver per year over a 12 year life at current reserve estimations. The mine was designed and constructed at a cost of $79.3 million with engineering and construction services provided by Davy McKee Corporation, San Ramon, California. Key Gold Fields operating staff were involved in the design of the facility from the start of the project: The Mine Manager, Plant Superintendent, Plant General Foreman, Maintenance General Foreman and Chief Metallurgist were all involved full time on the project within 5 months of the first ore discovery. Emphasis was directed at optimizing operating efficiency and in particular minimizing labor costs in the plant. It was recognized that a high level of instrumentation and control would be required to achieve this. The risk associated with the instrumentation and control systems implemented was to be minimized by using equipment and systems that had been proven in industry while utilizing the most cost effective, state-of-the-art technology available. The reliability of the overall control system was considered to be critical in view of the cost of downtime associated with the gold extraction plant. BRIEF PROCESS DESCRIPTION The dump leaching process treats approximately 1.2 million tons per year of low grade ore at an average grade of 0.035 oz/ton. Run of mine material is dumped on a lined leach pad and weak cyanide solution is applied by drip irrigation. Pregnant solution run off is pumped to carbon columns in the milling plant for gold recovery and the barren solution returned to the dump leach circuit. Average gold recovery is 60%. This process has little instrumentation and control associated with it. The milling operation treats 700,000 tons annually of higher grade ore (0.200 oz/ton initially, dropping to an average of 0.135 oz/ton after first two years). Recovery is directly related to head grade (fixed tail assay effect) and currently averages 96%. A single pass through a jaw crusher reduces run of mine ore to minus 12 inches. The ore is stockpiled and reclaimed by loader for grinding in a two-stage milling circuit consisting of a SAG mill and ball mill, the latter in closed circuit with hydrocyclones. Cyanide and lime are added into the SAG mill to start dissolution of gold as early as possible in the circuit. The ground product leaves the milling circuit at approximately 78% minus 200 mesh and is fed to an unique "double thickener" leaching-recovery circuit. This circuit has been discussed in detail in a paper by J. G. Mansanti et a1 (1). Two thickeners are arranged in counter- current configuration with three leach tanks. Overflow solution from the first thickener is treated by carbon-in-columns (CIC) for gold recovery with 85% of the soluble gold recovered onto this carbon. Underflow slurry from this thickener is pumped to the leach tanks, with a total retention time of 12 hours, and then gravitates to the No. 2 thickener. Overflow solution from the second thickener is used as a wash in the first thickener. Underflow slurry from the second thickener is treated in a carbon-in- pulp (CIP) scavenging circuit to recover the remaining 15% dissolved gold. Gold-loaded carbon from both the dump leach and milling circuits is stripped in batches using the Zadra hot caustic- cyanide elution process. Gold (and silver) is recovered from the hot strip solution by precipitation with zinc dust and the product recovered on Funda pressure filters. The precipitate is retorted to remove any mercury and then smelted into buttons. The buttons (approximately 80% gold, 15% silver) are shipped to an independent refiner in Salt Lake City, Utah, for further treatment.

Jan 1, 1990

By Malcolm J. Robinson

Over 80% of Australia's population lives within 200 km of the coast, 70% in 10 major coastal cities. Potential cement raw materials are widely distributed but deposit size, quality, transport, market and environmental considerations are important in determining economic value. Major production locations are in a variety of geological environments ranging from Lower Paleozoic crystalline limestones to Tertiary and Recent polyzoal limestones and limesands, both onshore and offshore. Raw material transportation is by road, rail, sea, aerial ropeway and pipeline; road/rail transportation of the finished product is traditional but movement by sea of clinker and cement is increasingly a feature of the industry.

Jan 1, 1982

By N. L. Hayward, V. H. Ness

In the past decade Australia has seen the development, construction and commissioning of three complex processing plants for the treatment of lateritic nickel ores. These have all been based on high pressure acid leaching (HPAL) for extraction of nickel and cobalt into solution, followed by solid liquid separation in a CCD circuit. However, flowsheets for separation and purification of the nickel and cobalt diverge markedly. The existing plants have been commissioned with varying degrees of success, with a variety of problems ranging from materials of construction to inadequate design. While the process problems are not insurmountable, there is much room for improvement. Currently there are several new HPAL plants at the feasibility or financing stage. All of these have adopted one of the existing flowsheets. Most of the enhancements have focused on increasing autoclave size. It is now time to assess the success and failures of the three existing plants and incorporate this experience in a design for productivity, efficiency and reliability. Towards this end, this paper discusses aspects of flowsheet optimization, materials of construction and engineering design.

Jan 1, 2001