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By B. W. Cavender

Innovative mining and metallurgical operating techniques or processes can be identified and developed by systematically analyzing change as it occurs within the mine, plant, technology, or industry. Sources of change to be monitored for innovative opportunities include unexpected successes or failures, incongruities between perceived and actual events, process needs, changes in perceptions, and the development of new knowledge. Innovation can be effectively organized, practiced, and managed. The perception of change as an opportunity rather than a threat is mandatory, as is the systematic measurement of innovative performance. Innovation is enhanced by specifically-designed policies regarding organizational structure and staffing, daily management practices, and compensation and incentives.

Jan 1, 1994

By S.K. SHARMA, ANKUSH GALAV, G.S.P. SINGH

This paper proposes a hydromechanically coupled numerical modeling approach to quantify the influence of various parameters on the mechanical and hydraulic performance of protective water barrier pillars (PWBP). The results are validated for two case studies having pillar widths of 16 and 42 m at cover depths of 136 and 190 m and water heads of 25 and 141 m. The outcome can be significantly helpful in the rational design of these pillars in underground coal mines.

Mar 1, 2023

By K. V. Raj, R. Jacksha

Conveyor systems persist in being a source of injuries and fatalities in the mining industry. To reduce these incidents, better methods are needed to enhance the monitoring of probable hazards and improve situational awareness during the normal operation and maintenance of conveyor systems. To address these issues, researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) continue to investigate emerging technologies that show the potential to improve miner safety around conveyors. This paper presents a feasibility assessment by NIOSH researchers of a fully integrated, commercially available wireless Internet of Things (IoT) system to improve situational awareness around conveyor systems.

By R. L. Wiegel

A well-defined geometric model for a mineral system and its liberation by size reduction is used to show the relationship between true volumetric particle composition and the composition estimates obtained by the measurement of linear intercepts or areas of simulated polished sections of particles. Based on this information, a transformation is developed between the areal measurements and the volumetric composition for this idealized mineral system. Key words: Gaudin random liberation model, Mineral liberation, Particle composition measurement

Jan 1, 2010

By V. E. Housman

EPA's Mining Waste Section within the Office of Solid Waste is continuing to collect and analyze information on mining waste management practices. Starting in 1991, the Mining Waste Section has continued to conduct site visits and prepare case study reports on the waste generation and management practices of operating mines. In choosing sites to study, a reasonable attempt was made to provide diversity in mining commodity types, geographic regions, geology, climate, and environment. To date, EPA has visited the following mines: Asarco Troy (copper) in Montana, Newmont Rain in Nevada (gold), Cyprus Thompson Creek (molybdenum) in Idaho, LTV Steel (iron) in Minnesota, Phelps Dodge Morenci (copper) in Arizona, Doe Run Fletcher (lead) in Missouri, Brewer (gold) in South Carolina, IMC Four Corners (phosphate) .in Florida, Pennzoil Culberson (sulfur) in Texas, Nerco Cripple Creek (gold) in Colorado, Copper Range White Pine (copper) in Michigan, Magma San Manuel (copper) in Arizona, Colosseum (gold) in California, and several gold placer mines in Alaska, including the Valdez Creek Mine. EPA has prepared a case study report on each facility. The mine operators were provided an opportunity to comment on their respective site visit report and their comments have been included in' each respective report. These site visit reports have in turn been incorporated into technical resource documents which provide a detailed description of each mining sector. EPA is currently reviewing the technical resource documents and plans to release the documents in the Spring of 1994.

Jan 1, 1994

By Douglas B. Silver

The key to unlocking value is to find opportunity where others have missed it. How does a company find value in a thoroughly explored asset? This article explores the approach taken by one company and the results it achieved from working this problem. The town of Shafter is located on a small bend in the road in west Texas' Big Bend Country. Its past emulates the glory days of so many other mining camps. A discovery was made, fortunes were built and World War II shut down the operation. The Shafter deposit continues to be one of the larg¬est undeveloped primary silver deposits in North America. Gold Fields Mining Co. recognized the area's potential in 1977 and embarked on studies to reopen and develop the district. Gold Fields spent $16 million on the Shafter project. It drilled more than 86,240 m (282,940 ft) in 475 holes, sunk two shafts and developed 1,550 m (5,100 ft) of underground workings. Today, the mothballed 447-kW (600-hp), single-drum Nordberg hoist and permanent production-type, single-compartment headframe continue to crown the shaft. Other buildings onsite house compressors, mine pumps, spare parts, drill core and other supplies. All these items look as though they arrived yesterday. By 1982, Gold Fields had completed an extensive feasibility study with ambitions to. construct a 1.36-kt/d (1,500-stpd) agitated cyanidation mill and base metal gravity circuit. Reserves at Shafter stand at 4.23 Mt (4.67 million st) grading 193.5 g/t (5.65 oz/st) silver. Gold Fields planned to produce 71.5 t/a (2.3 million oz/year) of silver at a head grade of 196.2 g/t (5.73 oz/st) silver with a 77% recovery rate. Cash costs were projected to be $5.54/oz with an anticipated initial and total capital cost of $46.2 million and $51.3 million (1984 dollars), respectively. The study assumed a silver price of $8.60/oz that has not been seen since the Hunt brothers quit buying silver. When silver prices declined, Gold Fields put the property up for sale.

Jan 1, 1999

By K. C. Ko

The pit slope angle dictates the economics as much as the depth of the pit. Steeper slope provides more ore reserves, at the same time, the steeper slope presents higher probability of instability and associated maintenance problems. While large open pit mines mostly belonged to nonferrous metals in the past, other mines are becoming deeper as the mine economics permits deeper mine operations, Such minerals include coal, uranium, phosphate, and others. There are some basic differences between an open pit slope and slopes that are encountered in usual civil engineering work such as dam embankments and highway cuts (Figure 1). The stability of the civil engineering slope changes continuously with time due to ground-water movements, weathering, etc. But the stability of the open pit slope (Figure 2) changes more drastically day-to-day or even hour-to-hour, These changes occur because not only is the slope geometry being continuously changed by the mining operation, but also different geology and geologic structures are being exposed on the slope. Even when a particular slope area is not presently being mined, excavation in adjacent areas can affect the general condition of that slope area. A pit will experience some slope failures during its life.

Jan 1, 1977

By F. S. Knoll

Electrostatic separation is one of the most misunderstood physical processes used to beneficiate minerals. Nonetheless, millions of tons of titanium ores, iron ores and other minerals are processed every year economically, efficiently and safely. Over the past ten years major advances in electrostatic separation and its application have occurred. New processes include dewatering clay slurries, separating halite and sylvite, and shape separation of vermiculite and gangue minerals. Electrostatic separation techniques are based on one of two methods, electrophoresis or dieleccrophoresis -- processes involving charged and uncharged particles respectively. In some cases, the combination of these two techniques has proven quite useful. The purpose of this paper is to provide a basic understanding of the physical processes collectively called "electro- static separation" in order to enhance one's ability to define and consider new possibilities in mineral processing and other fields.

Jan 1, 1984

By Jim Johnson

The purpose of this paper is to summarize and discuss a variety of site specific conditions which are typically evaluated as part of the engineering design process for heap leach pads, solution control ponds, and associated facilities. The following sections will focus primarily on the topographic, climatologic, hydrologic, and geotechnical evaluations critical to selection of heap leach sites, and selection of a preferred heap leach configuration or method. Other important considerations in the design of a heap leach project, including evaluation of ore properties and leachability, pregnant solution processing requirements, spent ore neutralization/disposal requirements, and other anticipated reclamation requirements are beyond the scope of this paper are not addressed in any detail.

Jan 1, 1998

By Jung-Joo Kim, Jong-Uk Kim, Turab H. Jafri, Han-Kyu Yoo

"INTRODUCTION Steel sets such as H-type and lattice girders are often installed in the tunnels before the hardening of shotcrete to ensure the stability of conventional tunnels in soft ground conditions. In practice, while designing the tunnels with the help of numerical analysis, steel sets are generally considered only as temporary support elements. Only a few studies propose the direct application of composite support in the tunnel design, based on large-scale experiments and numerical analysis. In order to assess the structural performance of the composite support consisting of shotcrete and steel sets, large-scale experiments were performed on two types of arch-shaped specimens by applying the combined effects of axial forces and bending moments. Based on the experimental results, numerical analysis was performed to assess the application of composite support in tunnel design. The crown settlement, axial forces, bending moments, and load distribution in the composite support were analyzed in the light of different structural patterns. LARGE-SCALE EXPERIMENTS USING COMPOSITE SUPPORT Preparation and Procedure of the Experiments The preparation setup as well as the organized procedure of the large-scale experiments using composite support is shown in Figure 1. An appropriate geometry of the specimens was selected by considering the standard cross-section of a two-lane highway tunnel in South Korea. Under the loading conditions meant to develop the axial forces and bending moments simultaneously, arch-shaped specimens were assembled with the ends of the specimens subtending a 60° arc angle at the center of the arc circle as shown in Figure 2. The fabrication of six specimens was completed in two groups based on the dimensions of steel sets, with the first group of three specimens being reinforced by H100 (No.1, No.2, No.3) and the other three by H125 (No.4, No.5, No.6). In order to reduce the voids on the boundary of the shotcrete and steel sets, concrete was casted over the steel sets instead of using shotcrete. The specimens were designed to incorporate the uniaxial compressive strength of 21 MPa. Shear keys and steel plates were installed at the ends of the specimens, so that shear failure could be avoided at the ends and the specimens could also be protected from detachment at the fixation. Translational and rotational movements at the ends of specimens were fixed."

Jan 1, 2016

By Kyle Kittle, Kyle Knaeble, Albert Ruiz, Gregory Raines, Ryan Gewargis

The Chimney Hollow Reservoir Project (CHRP) is located southwest of Loveland, Colorado. CHRP is a component of the Windy Gap Firming Project, operated by the Municipal Subdistrict of the Northern Colorado Water Conservancy District. The inlet/outlet tunnel (IOT) for CHRP contains a reinforced concrete lined alve Chamber with PC membrane waterproong that was ecavated via seuential ecavation method to a diameter of feet. The IOT was ecavated using both drill and blast and road header with ground support consisting of steel sets, rock bolts, wire mesh and shotcrete. The IOT will withstand 300 feet of water head and rock ll surcharge load from the dam embankment constructed over the tunnel.

Jun 23, 2024

By Ronald R. H. Cohen, Margaret W. Staub

Two pilot scale bioreactors designed to treat acid mine drainage primarily using sulfate reducing bacteria were constructed underground at the Eagle Mine Superfund site in Minturn Colorado. The project was designed to test th applicability of microbiological treatment on water with high metals concentration and to test the process in an underground environment. Objectives were, 1) to compare metal removal, pH increase, and sulfate reduction in a single stage reactor with a double stage reactor of equal volume at varying flow rates; 2) to determine where within the substrate treatment occurs· and 3) to examine volume versus surface ara as a design parameter for optimizing metal removal processes. Results from the reactors showed that the single stage reactor and double stage reactor performed equally well for the removal of Cd, Cu, Pb, Fe, Mn, and Zn. pH increased above 6.5 in both reactors. Greater than 97% of metals were removed within the first ten inches of substrate. Volume proved to be a more useful parameter for determining removal rates than area. Using volume as a design parameter rather than surface area enables PMDT systems to be constructed as packed columns rather than broad wetlands, Thus, space requirements are significantly reduced.

Jan 1, 1993

"Metallurgical process development in greenfield projects must define the comminution flowsheet and establish the equipment sizes that are required to deliver the project design criteria. These are critical steps that heavily influence the financial performance of the project, requiring a detailed understanding of the ore properties of the project resources and the best practice methods to size comminution machines. This paper reviews current practices for determining the ore characteristics relevant to comminution circuit design. Particular attention is given to the design of sampling and testing programs, and the methods commonly applied to size crushers and mills for conventional size reduction applications in mineral processing. IntroductionMetallurgical process development in greenfield projects requires the selection of a comminution flow sheet and must establish the equipment sizes required to deliver the project design criteria. This necessitates a detailed understanding of the ore properties that define the project resource. For brownfield projects the same objectives may apply for plant expansions, or the project objective may be simply to define the capacity and operating cost of an existing facility for a new ore source. The process development phase in either instance will typically comprise the following key activities:• Geometallurgical classification and sampling of the ore deposit or deposits.• Determination of comminution energy requirements.• Benchmarking similar projects.• Identification of flow sheet options.• Equipment selection and sizing.This paper is concerned specifically with process development testing and will as such focus on the first two activities on the list: sampling and testing of the deposit. The discussion will focus on testwork programs to support the design of comminution circuits commonly in use in mineral processing today, specifically crusher, tumbling mill and stirred mill technologies.It is important that any testwork program is designed giving consideration to the types of flow sheets that are viable for the project, and the data that will need to be generated to support the final equipment sizing. Designing a testwork program to only provide information about one particular type of flow sheet will not allow sufficient information to be generated for a rigorous trade-off analysis of options, and may therefore preclude financial optimization of the project. Testing programs should be designed to collect sufficient data to ensure that any backtracking at a later stage to fill in missing information is minimal."

Jan 1, 2016

By H. Sis, D. Dahlin, S. Chander, C. Summers

Bench-scale selective-flocculation tests were conducted on samples of Florida phosphate and Western phosphate process tailings to recover upgraded phosphate concentrates. After physical and mineralogical characterization, the slurry samples were treated with a broad suite of flocculants with a range of molecular weights and anionic functional groups. Parameters investigated included pH, dispersant and flocculant types, and dose; conditioning parameters and settling times were, for the most part, held constant. Where selectivity was achieved, phosphate minerals remained dispersed, whereas silicate minerals flocculated and settled. Single-stage tests using reagents with low to medium anionic characteristics produced upgraded phosphate concentrates at moderately elevated pH. Two- stage site-blocking tests, in which low-molecular-weight flocculants were used as site-blocking agents, gave improved results.

Jan 1, 2002

By R. E. Mitchell

The environmental impact assessment (EIA) is the accepted method for evaluating proposed mining and other industrial projects to obtain regulatory approval and to help companies plan for responsible development. Another increasingly common evaluation system for proposed projects is the environmental, social and health impact assessment (ESHIA). An ESHIA differs from an EIA for its generally more comprehensive and inclusive approach to evaluating potential impacts, such as on public health, and other features such as an ecosystem services approach to assessing biophysical and community impacts. An ESHIA may also be required by certain lenders for financing major projects. In this paper, EIA standards for the province of Alberta, Canada are discussed and compared to ESHIA. It concludes with several recommendations for consideration.

Jan 1, 2012

By S. N. Groudev

Intensive uranium mining activities at the Curilo deposit in Bulgaria has caused widespread contamination over a wide area. A number of receptors including soils and watercourses as well as the ecosystems in the area have been severely affected. Even today, 10 years after the cease of activities, acidic waters generated from the abandoned mining works, the low-grade ore and waste dumps contaminate soil, surface- and groundwater. The present paper describes in general the environmental status of the wider Curilo area and examines the potential of preventive and remedial measures that can be applied in situ to rehabilitate the site and restore the ecosystem. The main rehabilitation technologies examined include modification of the acid generation potential of the pollution sources, treatment of the acidic drainage by means of a natural wetland and in situ bioremediation the of contaminated soils. Finally, a number of efficient indicators are proposed so that the rehabilitation potential at Curilo and similar heavily contaminated sites is assessed.

Jan 1, 2003

By D. S. Yantek, R. J. Matetic, A. K. Smith, E. D. Thimons, J. Srednicki

In a 2007 report to the U.S. Congress, the Office of Mine Safety and Health Research of the U.S. National Institute for Occupational Safety and Health (NIOSH OMSHR) stated that built-in-place refuge alternatives (BIP RAs) provide significant advantages over mobile refuge alternatives. At present, the requirement to locate refuge alternatives within 305 m (1,000 ft) of working faces makes BIP RAs impractical in most coal mines. BIP RAs would be practical if three issues are addressed: (1) allowing BIP RAs to be located at greater distances from the working face, (2) developing a reliable process for the design and approval of BIP RA stoppings that meet the 0.1-MPa (15-psi) design criteria, and (3) developing systems that reliably deliver breathable air to the refuge alternative. In 2015, NIOSH OMSHR conducted a study of these three issues and issued a report. In the report, justification was provided for allowing the placement of BIP RAs at greater distances from the working face than the currently mandated 305 m (1,000 ft), guidelines were developed that could be used by industry when submitting BIP RA stopping design applications for approval which are patterned after the Mine Safety and Health Administration guidelines for coal mine seal design applications, and insights were provided into options for providing a reliable supply of clean, breathable air to BIP RAs. This paper presents a summary of the study’s findings and also addresses issues discovered during the building and designing of a BIP RA that OMSHR researchers constructed in NIOSH’s Experimental Coal Mine in Pittsburgh to research the testing and improving of BIP RAs. These issues include several issues related to the delivery, distribution and exhaust of ventilation air to the BIP RA and some general construction issues that require further investigation.

Jan 1, 2016

By James W. Echerd

Anthracite preparation developments, particularly in the early days of the anthracite industry, formed the basis for the modern coal preparation plants that have become so essential to the coal industry today. The anthracite industry, from early in the 19th century until relatively recently, was a leader in mining, preparation and marketing of coal, and played a leading role in the development of the industrial America we know today. Anthracite was discovered in America in about 1760--the story of Necho Allen is well known--but the rediscoveries leading to mining operations took place about 50 years later. The Wurtz brothers in 1815 at Scranton, the Smith brothers at Wilkes-Barre in 1807, Beach in Hazleton in about 1814, and Boyd in 1816 at Shamokin were all instrumental in promoting early mining and marketing of anthracite (J3. The early canals and railroads were built for the specific purpose of moving anthracite to the market areas. Eventually, the industry grew until, in 1917, it reached a production zenith of a little over 100,000,000 tons, representing about 20 percent of the total coal output in the United States. Almost half of the anthracite produced that year was consumed for domestic heating, a utilization that had dominated the industry for almost 100 years. Initially, anthracite had to be used by gunsmiths and blacksmiths, after which had followed the consumption of extensive quantities for railroads, blast furnaces and foundries, and electric power generation. Most of the markets have been lost to coke, oil, and natural gas. Near the anthracite regions, however, significant quantities are still used for domestic heating, power generation, carbon black manufacture, blending with bituminous coal to make metallurgical coke and fuel, and for other industrial purposes. Thus, anthracite production has not been entirely committed to history, but remains an active industry that follows modern practices in the mining, preparation, shipping, and utilization of a fuel that is still a valuable adjunct to the national economy. In fact, its inherent low sulfur content may make it an important fuel of the future. Estimates indicate there are reserves of anthracite to last for 300 years at a consumption rate of 50,000,000 tons/year. Anthracite Preparation Yesterday A 170-year history of the anthracite industry obviously is not the purpose of this discussion. A complete history of anthracite preparation, the rather unglamorous step in the processing of "mine run" hard coal to make it suitable for the user, is also not practical. Hence, the purpose of this report is to trace the development of some of the most important processes used through the years to meet a part of the demand for energy developed by our modern society. Anthracite preparation in the early days of the industry consisted solely of separating slate from the coal, by hand, underground (Z). This method prevailed for almost 20 years until wrought iron hand rakes were introduced to separate the large and small sizes. Shortly thereafter, the first attempts were made to size and clean the coal aboveground. The coal was dumped on a perforated cast iron plate, and men used sledge hammers to break the larger pieces into smaller sizes suitable for the market. The smallest sizes--that is, the material that went through the plate--were thrown away because they had no value at that time--a concept that existed for many years and actually was the basis for the subsequent "river" coal production and the many silt banks which are landmarks in the anthracite region. The larger sizes, at that time, sold for 50 cents per ton. The Batten breaker, or roll crusher, was invented in 1844, followed soon thereafter by the Snell-Diehm breaker (A). The latter had disadvantages, including excessive waste and fixed product size, but it later was improved in these respects. A breaker was also developed at Minersville, Pa., at about the same time that processed 200 tons of coal per day, using roll crushers and circular screens (1). Handpicking, from the beginning of anthracite preparation, was an important part of the cleaning process and was still being practiced as late as 1950. It was this process that involved the "breaker" boys of coal region lore. How much good handpicking accomplished depended on how much impurity was present in the coal--the more the impurities, the greater the reduction in ash. Thus, high-impurity streams were significantly improved, whereas picking of relatively clean coal was mainly to show an effort to make a quality product. As indicated, picking is largely a visual operation. It was and is wasteful of coal in the larger sizes since some good coal is always associated with the bad. However, it was probably much more effective' in the larger than the smaller sizes.

Jan 1, 1971

By Pedone Ezio Michele, Mohamed Dahir Holad

"The 4c segment is a part of the ""Oman National Railway Project” linking the mining area in the surroundings of Thumrait and the port of Salalah. It is 90 km long and the last 40 km stretch crosses a mountainous area near the city of Salalah. The project includes the excavation of a 33 km double and single bore tunnel and 10 km of safety tunnels. This mountainous area is a holiday destination for Omanis, thanks to its beautiful landscapes, especially in summer time due to the monsoon rains. The tunnelling design had to take into account both these environmental constraints and the limestone rock formations crossed, which are affected by significant karst features. Given the context, the conventional tunnelling method has been preferred. INTRODUCTION The Oman Railway Project (Fig. 1) covers the construction of approximately 2,150 km of railway line for freight and passenger transport which will connect together Oman’s main towns and industrial sites and it will form part of the Arabian Peninsula railway system “GCC Project”. The non-electrified double-track railway line must guarantee a speed of 220 km/h for passenger trains and 120 km/h for freight trains and must guarantee the transit of AAR (Association of American Railroad) H and D plates using clearance envelope according to AREMA (American Railway Engineering and Maintenance-of-Way Association) requirements. The design alignment must have maximum radiuses of curvature of 3,250m and a maximum gradient of 1.0%. The project is divided into 9 constructional and functional segments. •,Segment 4c will be constructed in the southern region of Oman, close to the border with Yemen, to connect the town of Thumrait with the Port of Salalah. •,Segment 4c will run through the Dhofar region and will be mainly used by the freight traffic which currently travels by road."

Jan 1, 2016

By P. O. Lindahl

The U.S. Bureau of Mines initiated research to improve the safety and efficiency of transporting coal from deep underground mines using a balanced air-lift hydrohoist. A 50-m-high pilot-scale model was constructed and tested to evaluate the feasibility of hydraulically hoisting a coal-water slurry in a U-tube pipeline from the mine level to the surface with the assistance of compressed air. A prototype screw feeder is used to continuously compact and inject 5-cm or less run-of-mine coal into a pressurized 20-cm-diam pipeline. Production rates up to 40 metric tph at an airflow of 1.5 m3/min were achieved with the model, and coal size degradation was relatively minor. Modifications are in progress to achieve 100 tph at an airflow of 2.8 standard m3/min injected into the riser pipe. Pilot-scale results indicate that an air-lift hydrohoist system is a feasible, cost-effective alternative to conventional skip hoisting that can be installed in existing shafts or surface-drilled holes closer to the face area. Air-lift hydrohoisting offers advantages of infinitely adjustable slurry flow rates, reduced pressure at the point of coal injection, and flexible design that can be combined with hydraulic pumping. Proposed design changes are discussed for coal transport, mine layouts, ventilation, fire control, and escapeways using this system.

Jan 1, 1995