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By James J. Gusek

The Atlantic City iron mine is located in Fremont County in central Wyoming, near the historic gold mining camps of Atlantic City and South Pass City. The mine lies on the southeast flank of the Wind River Mountains at an elevation of about 2,470 m (8,100 ft) above sea level (Fig. 1). An 81-h M2 (200-acre) tailings impoundment at the Atlantic City taconite operation has been a source of blowing dust. The site qualified for reclamation under Wyoming&apos;s Abandoned Mine Land (AML) reclamation program. The ultimate reclamation construction incorporated commercially available organic amendments and fertilizers into a 300-mm- (12-in.-) thick cap of a sterile clay loam cover material. The water level was lowered in an adjacent flooded mine pit that was feeding uncontrolled seeps into the tailings basin. A wide tailings pond spillway was built that allows flood control while minimizing seasonal water-level fluctuations in the pond. Rock berms and rock snow fences were built for wind-erosion control and soil-moisture preservation. Future work includes tree planting in the protective wind/ snow shadows of rock berms and rock snow fences and plugging a decant pipe. US Steel opened the Atlantic City iron mine in August 1962. It closed in 1983. Taconite iron ore was mined by surface methods. The ore was magnetically separated from the waste. The magnetic concentrate was mixed with bentonite, formed into pellets and roasted to produce a blast furnace feed stock for US Steel&apos;s blast furnaces in Geneva, UT. The pellets were hauled by rail to the Geneva Iron Works. The Atlantic City Mine produced three types of wastes. These included waste rock overburden from mining, a coarse-grained (sand to small-gravel sized), nonmagnetic reject rock termed "cobbs" and fine-grained tailings ranging from 600 to 75 µm (28 to <200 mesh). The waste rock has been used as an aggregate/rip rap source by a local contractor and the Wyoming Department of Transportation (WYDOT). WYDOT also

Jan 1, 1998

By P. Koh

A novel approach incorporating computational fluid dynamics (CFD) and flotation modelling has been used for investigating flotation cell designs. CFD modelling has increasingly been employed to enhance understanding of the cell hydrodynamics in mineral and coal flotation. Opportunities for improving the flotation cell performance can be identify by modelling. The CFD-flotation model from CSIRO incorporates cell hydrodynamics that affect particle-bubble interactions. Information from the model includes velocities, turbulent dissipation rates, gas hold-up, particle-bubble attachment and detachment rates. The attachment and detachment rates have been found to be effective measures of cell performance for cell design.

Jan 1, 2011

By R. P. King

A new device, called the dual impact load cell, has been developed and built at the Comminution Center to measure fracture energy and damage accumulation in brittle particles that are subject to impact. The results show that damage accumulation during impact is not a significant factor in determining the fracture energy or the particle strength. However, predamage induced by thermal pretreatment of the particles has a significant effect on both fracture energy and particle strength.

Jan 1, 1995

By Aditya Rana, A. K. Mishra, M. M. Singh, N. K. Bhagat

Many cases of derailments, train accidents and traffic interruptions due to the slope failure and rockfall have been reported in the past on Konkan Railway trackline because of unstable rock slopes. The authorities installed stability enhancement measures such as wire netting, rock bolting and shotcreting which were found insufficient. The failed geotechnical measures prompted authorities to excavate the unstable slopes. Rock blasting is generally not preferred for the excavation of slopes along the transportation route. Stabilisation and widening of slopes by blasting need closure of the route for a considerable time. Discontinuing traffic on Konkan Railway route was undesirable as it connects two important port cities Mumbai and Mangalore. The paper presents an innovative directional controlled blasting (DCB) technique for excavating three unstable slopes (i.e. cuttings) in hilly terrain without disturbing the traffic. New empirical formulae for small geometry blasting to estimate burden and throw have been developed. A unique sequence of firing and excavation with powder factor varying between 0.04 and 0.39 kg/m3 irrespective of the actual free face was used for rock blasting. The process controlled the throw of blasted material over the track and resulted in a smooth and stable wall. The slope angle has been changed from 80 to 82° to 45–47° and probability of wedge, planar and toppling failures was eliminated. About 100 such accident-prone slopes (52 km cumulative length, 7% of total route) situated at discrete locations along Konkan Railway route were stabilised using the technique. No incident of rockfall and slope failures along these slopes has been observed after the stabilisation.

By C. Dan Kealy

Recent antipollution legislation for the control of mine tailings and waste-water has required an increasing number of tailings ponds. Many of these new waste-retention ponds are being constructed in congested locations, or the older ponds have reached such a size that--if failure occurs--they pose a threat to human life and public property. Although the typical tailings-disposal embankment represents--to the casual-, observer or the economy-minded mine official--a rather ugly but benign and stable pile of waste, they are in fact an extremely sensitive structural mass, retained behind the frailest of dikes. Failure of the waste mass requires only a minor change in water retention or weather conditions, erosion or piping of the ground strata, shifts in load or slight earth tremors. When failures occur, the results can be disastrous. In the U.S., we have been fortunate that, so far, pond failures have not caused loss of life. Thus, failures in this country have attracted little public attention. Present tailings-pond construction methods used by the mining industry require the barest money investment, and little engineering effort. Unfortunately, this superficial approach may increase short-term profits, but the practice may be conducive to the construction of needlessly weak structures. In coming years many of these designs will probaly become corporate liabilities. A typical pond is portrayed in Figure IA. This particular pond in Arizona is 1 mile long and 3/4 mile wide. Illustrated in Figure lB is a representative pond in cross section. This paper in concerned with two basic features common to all tailings disposal: (1) location of the phreatic surface within a tailings-pond embankment because of its influence on embankment-slope stability, and (2) prediction of

Jan 1, 1971

By T. J. Lien

AMAX Coal Company&apos;s Belle Ayr coal dryer is the first industry attempt to commercialize sub-bituminous coal drying which has been the subject of laboratory and pilot plant tests for almost two decades. This paper presents the historical background, construction, start-up and operation of this adaption of fluidized bed coal drying technology to Powder River Basin coal. The flowsheet and operational problems encountered during plant start-up are discussed together with general material balance and product quality.

Jan 1, 1990

By H. A. Kortmann

For the commercial production of iron ore pellets from hematite ores, as it is practiced in various pellet plants, the addition of lime has shown to be an efficient means with a view to improving cold compression and abrasive strength of the indurated pellets considerably. Unfortunately, it has also been shown at the same time, that the metallurgical properties as, for instance, swelling behavior, softening during reduction under load and disintegration of the grain, can be adversely affected to a high degree. In the course of smelting tests carried out by renowned steelworks, blast furnace operation was heavily disturbed by the swelling and early softening of the pellets, also by their disintegration in the low-temperature range, which altogether led to a considerable lowering of the smelting rate (1, 2, 3).

Jan 1, 1972

By A. A. Dor

Recent developments in the design of concentration plants have reflected the increased recognition that has been given to the economic and metallurgical advantages of autogenous grinding. This has manifested itself in the increasing adoption of primary auto genous grinding in iron ore &apos;beneficiation plants in North America. Table 1 lists eleven major iron ore beneficiation plants which have either been put in operation since 1961 or are under construction at present. Seven out of these eleven plants have adopted primary autogenous grinding. Four of them have coarse grinding mills (8 to 14 mesh) and three have fine grinding primary circuits (48 to 65 mesh). Their nominal capacity totals 26. 2 million ltpy of concentrates or pellets, representing very nearly 75% of the aggregate capacity 135. 3 million ltpy) of the eleven concentrators listed. For a long time there was a tendency to consider that primary autogenous grinding was only applicable to suitable coarse grained ores, However, extensive testing of a very wide variety of ores, and actual operating performance in several commercial plants, seem to have established beyond reasonable doubt, that the majority of mineral ores which the beneficiation engineer may be called upon to process can be ground autogenously. The basis for the selection of autogenous or conventional grinding mills, becomes principally economic and depends on the liberation characteristics of the ores under consideration and their relative hardness and grindability.

Jan 1, 1965

By Terry B. Linde, William M. Dowall

The recently completed In-Pit Crushing and Conveying Project at Phelps Dodge&apos;s Morenci Mine is rated among the world&apos;s leading materials handling projects. The operation involves the crushing and transport of more than 109,000 tonnes per day of copper ore, utilizing regenerative conveyors capable of providing over 5.5 megawatts (7,000 hp) of equivalent electrical energy. This paper describes the key aspects of the project and includes: Original project objectives; System design criteria; System description; Optimization studies; Major design features; Equipment description; and System commissioning.

Jan 1, 1993

By C. J. Bise, P. Bucks

Central Appalachian coal reserves are a valuable natural resource in high demand, both domestically and internationally, justifying efforts to increase percentage recovery through pillaring. Unfortunately, the challenge associated with pillar extraction introduces additional safety risks during the activity. Although pillaring developed prior to mechanized mining, current technology and mining practices have made this form of mining highly modernized. However, current fatality trends suggest that work still needs to be done to control the residual risk that is not controlled by modern practices, such as those having a personnel-performance-based component. This paper investigates the application of modern coal pillaring techniques and will present a risk-management-based strategy that targets personnel-performance-based risk, in order to improve the ability of safety engineers, managers and trainers to provide training programs addressing the needs of pillaring sections.

Jan 1, 2012

By J. Peterson, R. Michael, D. Yantek, E. Ferro

Among underground coal miners, hearing loss remains one of the most common occupational illnesses. To address this problem, the U.S. National Institute for Occupational Safety and Health Office of Mine Safety and Health Research (NIOSH OMSHR) conducts research to reduce the noise emission of underground coal mining equipment, an example of which is the roof bolting machine. Field studies show that, on average, drilling noise is the loudest noise that roof bolting machine operators would be exposed to, and it contributes significantly to the operators’ noise exposure. OMSHR has determined that the drill steel and chuck radiate a significant amount of noise during drilling. OMSHR and the Corry Rubber Corporation (CRC) have developed a bit isolator that breaks the steel-to-steel link between the drill bit and drill steel and a chuck isolator that breaks the mechanical connection between the drill steel and the chuck. This effectively reduces the noise radiated by the drill steel and chuck and in turn reduces the noise exposure of roof bolter operators. This paper documents the evolution of the bit isolator and chuck isolator. Laboratory testing confirms that production bit and chuck isolators reduce the A-weighted sound level generated during drilling by 3.7 to 6.6 dB.

Jan 1, 2011

By K. V. Raj

As open pit mines continues to grow deeper, managing air pollution can become challenging. During arctic air inversion, the temperature of the air over the mine increases with altitude, and the cold, heavy, surface air is trapped in the pit. This problem is complex, and any solution will require an extensive understanding of the interactions between the aerodynamic movement of air, air inversion, meteorology, pollutant sources, and transport phenomena in the open pit mines. The availability of computational fluid dynamics (CFD) has elucidated the pollutant flow mechanism in open pit mines. Very few CFD studies have been published, especially the Large Eddy Simulation (LES), on the contaminant transport in deep open pit mines under arctic air inversion. The contaminant transport in an open pit mine under arctic inversion is due to a stable or nocturnal boundary layer in micro-meteorological terms. Understanding the physics of the stable boundary layer (SBL) is relevant to air flow and pollutant transport in deep open pit mines. This paper focuses on a Large Eddy Simulation (WMLES as Sub-Grid Scale Model) modeling of the SBL and pollutant transport in a large open pit mine.

Feb 23, 2014

By K. L. Boyd

"Can the ever-increasing tonnages of ore and waste being mined today be accommodated simply by using bigger and better crushers? This paper reviews the latest primary crushing and large cone crusher designs. It highlights how—in addition to using the larger crushers now available—maximizing the utilization percentages in each of the four stages of the rock size reduction circuit will assist in meeting the larger production requirements of existing and new mining operations. Its goal is to help consultants and operators select the optimal equipment and custom-designed items in the material handling flowsheet from the mine to the mill, maximizing operating hours per year. INTRODUCTION Are larger crushers the answer to meeting the demands of existing or new mining projects for increased tonnage? Boyd (2002) predicted that larger crushers for primary and fine crushing would be beneficial and contribute to the further development of mineral processing. Larger crushers for primary and fine crushing applications are now available. The rock size reduction process from the mine to the selected milling process facility has not changed since man first broke a rock to get at the interesting mineralization within. The rock size reduction process circuit from the mine to the mill can be summarized in four stages: • Stage 1: Mining (rock breakage and fragmentation) • Stage 2: Pre-screening (scalping) • Stage 3: Primary crushing • Stage 4: Fine crushing (secondary, tertiary and quaternary) Plant throughput and ore delivery schedule will form the basis for flowsheet design and equipment selection. Once the project design criteria and the mine plan have been established, the circuit’s utilization percentage (percentage of hours when the circuit is being utilized) can be optimized for each of the four stages. The mining and process departments are the key stakeholders in the selection of the final comminution circuit, and both departments should be familiar with and contribute to the design of the circuit. This paper focuses on the four stages of a rock size reduction circuit from the mine to the mill, equipment selection, various ore and waste handling flowsheets, and improvements in crusher station design, all with the purpose of maximizing availability and plant utilization percentages. What is a large tonnage? From 1907 to 1914, the American Panama Canal excavated 300 million tonnes of material in 7 years (History of the Panama Canal, Wikipedia). Today’s large mining operations can move the same material in 10 months, using large crushers or multiple crushers for ore processing and large crushers and a mixture of truck haulage and conveyors for handling the large waste tonnages. Some examples include:"

Jan 1, 2017

By J. Noll

There is a need for direct tailpipe sampling of diesel vehicles in mines in order to determine the effects of an emissions-based maintenance program, evaluate control technologies such as diesel particulate filters and identify the worst diesel particulate matter (DPM) emitters in a fleet of vehicles. therefore, this study examined the performance of three portable instruments: a personal dust monitor (PDM) manufactured by thermo Scientific, a prototype elemental carbon monitor (Airtec) manufactured by FLIr and a prototype Ae91 instrument from Magee Scientific. These instruments were evaluated on the basis of their ability to provide direct reading tailpipe analysis for DPM. It was determined that the average bias of the tailpipe results from the PDM and the Airtec were 3±12% and 4±20%, respectively, when compared to the standard method of determining tailpipe particulate concentrations from a diluted exhaust. It was also determined that the Ae91 instrument correlated with the standard method.

Oct 1, 2013

By George J. Saulnier

The U.S. Geological Survey has developed mathematical-modeling techniques to assess potential impacts on the hydrologic system resulting from mining of coal and oil shale in northwestern Colorado. Potential impacts of oil-shale mining on ground-water hydrology have been simulated using a quasi-three- dimensional finite-difference model. The model has been used to simulate hypothetical mine-dewatering operations at two proposed oil-shale mines. Dissolved-solids distribution and solute transport were simulated with a three- dimensional finite-difference model that was used to evaluate the effects of flooding in hypothetical abandoned mines. The potential impacts of coal and oil-shale mining on watersheds were investigated using a digital watershed model. This deterministic physical- process model predicts responses of the hydrologic system to modifications resulting from mining in basins having snow as the major source of runoff and recharge. Potential impacts of coal development on surface-water quality were investigated using a river-quality assessment model.

Jan 1, 1979

By Samuel A. Rasmussen

Lead anodes are used in commercial copper electrowinning operations, yet there is no method to calculate anode life. To be discussed in this paper are operating characteristics of rolled plate (Pb,Sn,Ca) alloy anodes at Morenci&apos;s electrowinning tankhouse along with fundamental operating conditions and how the anode reacts to these conditions. These include anode maintenance, electrolyte temperature and viscosity, cobalt concentration, and manganese concentration. Also to be discussed are anode substrate characteristics under normal operating conditions and how the corrosion rate is affected by changes in operating conditions.

Jan 1, 1995

By Robert R. Dorfler

AMPS[. has completed a rationed grinding ball test in a 2.93 m x 2.93 m ball mill at Climax Molybdenum Company. The test consisted of purging the ball distribution formed by charging 100%, 76 mm carbon steel balls with a distribution formed by charging 50% 76 mm and 20% 51 mm alloy steel balls. The resulting change in ball surface area yielded improvements in both tons ground and fineness of grind with a significant reduction in total ball consumption. This paper summarizes preliminary studies leading to the plant test, grinding efficiency results, and future plans to optimize the ball charge.

Jan 1, 1981

By M. G. Eiselein, R. A. Smith, C. H. Sheerin

FMC Gold&apos;s Paradise Peak Mine was one of the top two producers of mercury metal in North America in 1988 and 1989. As a by-product, elemental mercury is produced from cyanide soluble mercury minerals, primarily to reduce the health risks incurred with the refining of precious metal precipitate containing elemental mercury and mercury amalgams. A discussion of the design, primarily the Merrill-Crowe units, and permitting for the safe production of mercury will be presented. Additionally, laboratory testwork to determine the effect of mercury on reagent requirements in the Merrill-Crowe process will be discussed.

Jan 1, 1990

By W. C. Hirt

Selective flocculation was used to produce superclean zinc concentrate with minimized silica contamination. Research was carried out on a flotation concentrate from the Jersey Miniere Zinc Company (JMZ) in Gordonsville, Tennessee. The material was first dispersed with sodium silicate and then causticized tapioca starch was used to selectively flocculate the sphalerite, leaving the silica in suspension. This technique has been applied commercially to iron ore beneficiation but has never been used for processing zinc. The feed material assayed 0.45% Si02. Use of 0.56 kg/tonne (1.13 lb/st) of sodium silicate and 0.070 kg/tonne (0.141 lb/st) of causticized tapioca starch resulted in 98.2% zinc recovery in a purified zinc concentrate assaying 66.0% Zn and 0.24% silica. The present target level for silica contamination in JMZ zinc concentrates is 0.3% Si02. This work has shown that selective flocculation offers a potential method for cleaning flotation concentrates, particularly where low silica products are required.

Jan 1, 1993

By W. R. Reed, D. E. Pollock, T. W. Beck, J. A. Organiscak, J. D. Potts

"In underground continuous mining operations, ventilation, water sprays, and machine-mounted flooded bed scrubbers are the primary means of controlling respirable dust exposures at the working face. Changes in mining arrangements, such as, face ventilation configuration, orientation of crosscuts mined in relation to the section ventilation, and equipment operator positioning, can impact the ability of dust controls to reduce occupational respirable dust exposures. This study reports and analyzes dust concentrations measured by the Office of Mine Safety and Health Research for both remote-controlled continuous mining machine operators and haulage operators at ten U.S. underground mines. Results of these respirable dust surveys show that continuous miner exposures varied little based on depth of cut, but are significantly affected by ventilation configuration. Haulage operators experienced elevated concentrations in blowing face ventilation. The type of cut influenced exposures, with elevated exposures observed for both continuous miner operators and haulage operators when working in crosscuts driven into, or counter to, the section airflow. Individual cuts are highlighted to demonstrate instances of minimal and excessive dust exposure attributable to particular mining configurations. These findings form the basis of recommendations for lowering face worker respirable dust exposures when performing a variety of continuous mining cuts.INTRODUCTION Underground continuous coal mining operations may encounter a wide range of conditions and arrangements during production and development activities. These activities typically produce respirable coal mine dust, putting operators of continuous mining machines and coal haulers at risk for elevated exposures. In order to comply with federal regulations limiting respirable dust exposures for the duration of a working shift, mine operators typically implement ventilation, water sprays, and machine-mounted flooded-bed dust collectors (scrubbers) to dilute and control mine dusts during coal cutting. Nevertheless, changes in operational conditions can limit the ability of these controls to effectively reduce dust exposures. Some examples of conditions that can change during the course of mining include face ventilation configuration, orientation of crosscuts mined in relation to the section ventilation, and operator positioning. Because these arrangements are largely under the control of mine operators, any insight into associated exposures may inform future plans and behaviors, reducing occupational exposures to respirable dust. The objective of this OMSHR study is to evaluate respirable dust exposures associated with a range of continuous mining arrangements by comparing occupational dust concentrations measured during a series of field surveys. These comparisons consider face ventilation configurations, depths of cut, and crosscut mining practices."

Jan 1, 2015