Search Documents

By James A. Deane

Strip mine reclamation Fs the process of restoring the land affected by the mining process to its most productive use. This can be timber production, pasture, crop land, wildlife and/or recreational use. The mining companies must determine, through the advice of their technicians, what the most advantageous use of the land will be. If the Company does not own the surface, the owner or owners must be contacted to determine their desires as to how the land should be reclaimed. Many times, in making the plans to restore an area with vegetative cover, the watershed and the quality of the water in the area is overlooked. The water itself must be an integral part of the reclamation plan. Many lakes and/or pits can be created with proper planning. In areas in the Midwest, where lakes are a scarcity, these strip mine lakes can become storage reservoirs for large amounts of water, They can help control runoff and low flow augmentation. The strip mining operation will affect the watershed regardless of whether a reclamation plan in made or not. It is up to the reclamation technician to see that the plan benefits the watershed instead of affecting it adversely. This can be done during the operation by intercepting the water before Pt enters the active pit. Diversion ditches above the highwall will handle the runoff water from the watershed. Water that does gain entry into the pit should be removed as quickly as possible. If the rules and regulations adopted by the Ohio River Valley Sanitation Commission in Resolution 5-60 are followed, water encountered during the operation can be handled with little or no adverse effect to the receiving watershed.

Jan 1, 1965

By A. Jolly, A. R. Kumar, T. Novak

"Coal dust in an underground mining environment has always been a health and safety issue, especially with longwall faces. Efforts to integrate a flooded bed scrubber within a longwall shearer are underway at the University of Kentucky (UK) in order to reduce worker exposure. Small scale physical modeling, along with numerical modeling and full-scale experimentation, are engineering tools being used by the authors for simulating operating conditions underground. Recent advances in affordable 3D printers offer a means for fabricating accurate, scale models for obtaining timely insights prior to building large, expensive test setups. Comparing scale-model results with those of numerical modeling, such as computational fluid dynamics (CFD), lends guidance and confidence in a proposed design. This paper discusses the small scale physical modeling of a longwall shearer with an incorporated flooded-bed dust scrubber in its operating environment. A tracer gas was used in the model in lieu of dust to measure dust-capture efficiency. Results obtained from the physical model are presented and compared with those of CFD model. The small scale model and the CFD results demonstrate good agreement. Dust capture results show the usefulness of the approach in advance of actual design implementation. INTRODUCTION Dust generation is an undesirable, but innate, byproduct of all mining processes. It is particularly problematic in underground coal mining, where coal dust poses potential hazards from two fronts – health and safety. Coal workers’ pneumoconiosis (CWP), commonly referred to as black lung, is a chronic lung disease that results from the long-term overexposure to respirable coal dust. Although the prevalence of CWP has steadily and significantly declined over the three decades following the Federal Coal Mine Health and Safety Act of 1969, a study by the National Institute for Occupational Safety and Health (NIOSH, 2008) indicates that significant health hazards associated with respirable dust still exist within the coal mining industry. In addition to being a health hazard, coal dust can also create a potentially catastrophic safety hazard. Dust that is not captured or removed at its source is suspended and transported throughout a mine by the ventilation airstream. This float dust is subsequently deposited on all mine surfaces along its travel path. Without adequate application of rock dust to these surfaces, forces from a localized methane ignition can reintroduce settled coal dust into the airstream creating an explosive mixture. Therefore, capturing and removing coal dust at its source mitigates the probability of two major hazards that continue to plague the mining industry."

Jan 1, 2016

By C. Bemelmans

Lead alloys function effectively as oxygen evolving anodes in copper SX-EW operations and are highly resistant to corrosion. The presence of organic from solvent extraction in the electrolyte seemed to enhance solution line attack. Laboratory tests showed that lead is soluble in D2EHPA, Acorga and LIX 984 to a limited, yet measurable degree. Lead alloys and various lead phases formed on the anode were tested to evaluate their effect on the corrosion process in organic media. Possible causes for anode corrosion and mechanisms responsible for their initiation will be discussed.

Jan 1, 1996

By A. D. Davis

A ground-water flow model was developed to simulate the post-mining recharge rate at the Belle Ayr surface coal mine in the Powder River Basin near Gillette, Wyoming. State regulations of Wyoming require that reclaimed lands should provide a rate of recharge that approximates the pre-mining rate. Steady-state calibration and transient simulations showed that the post-mining recharge rate in backfill is at least five centimeters per year, exceeding the original infiltration rate of 0.4 centimeters per year to shallow, overburden aquifers. Major reasons for the increase include the flat topography of reclaimed areas and decreased spoil density. It is expected that the backfill will disaggregate and settle over time, eventually resulting in a nearly constant recharge rate less than five centimeters per year but somewhat greater than the pre-mining rate.

Jan 1, 1995

By O. J. R. Baena, D. E. Chaverra, C. D. L. Ramirez

Cyanide is one of the most used reagents in the precious metal extraction process; as well as the most efficient from the point of view of the dissolution process; but it is also a toxic product that requires a lot of care in handling. Likewise, the residual solutions of the process must be followed because they can be a risk of contamination of water, animals and human health. In the artisanal processes of obtaining gold and silver, neutralization of the residual solutions is used to passivate the present cyanide. During this process ammonium cyanate is formed which decomposes rapidly in the presence of air and sunlight in carbon dioxide and ammonia gas, contributing to the greenhouse effect. In this work the use of the ammonium cyanate obtained in the process of neutralization of the cyanide solutions as a reagent to obtain urea is proposed. Urea was obtained indirectly through the use of the reagent kit UREA/BUN-COLOR. The process is effective at pH ≤ 4.5 with a rapid increase in solution temperature, and addition of hydrogen peroxide. The urea crystals begin to form at 50°C. The cyanide / urea ratio obtained was 1 / 7.5 INTRODUCTION In the processes of extractive gold metallurgy, the use of cyanide leaching is perhaps the most widely used method worldwide; by the ease of operation, its low cost and high levels of precious metal recovery. However, neutralization, in most processing plants, is not done properly, and leftovers of solution with free cyanide are dumped in concentrations harmful to the environment, in particular animals and humans. Cyanide can enter surface water through releases from industries using cyanides. Due to its high toxicity, the presence of cyanide in water is a matter of great concern (Jawale et al., 2017). The pollution generated by the effluents from the leaching of gold ores is one of the main obstacles of social opposition presented by mining activity due to the impact of both surface and groundwater. During the cyanide decomposition process, a compound known as ammonium cyanate OCN(NH4), which is a raw material for the manufacture of urea, CO(NH2)2 is generated. In the case of good neutralization, cyanide is no longer a toxic compound through oxidizing reagents, but as a result, there is the generation and emission of ammonia and carbon dioxide into the atmosphere, generating both a greenhouse effect (Gómez, 2012). This is evidenced by the strong effervescence of the reaction, and a penetrating smell of ammonia, which can irritate respiratory mucous membranes and eyes; however because they are greenhouse gases they are considered pollutants.

Jan 1, 2019

By Y. T. Auck, M. E. Kukura, L. G. Stevens

At its Technical Development Center in Tucson, Arizona, the UOP Mineral Sciences Division operates a completely integrated pilot plant testing a proprietary process for the extraction of nickel from limonite/saprolite ores. The process is based on the reductive roast- ammonia leach procedure now employed in several plants around the world. The process improvements are such that nickel extractions well above that experienced in these processes are possible, particularly on the more garnieritic/saprolitic ores. This paper will describe the process and the results of process development studies. The data show that pilot plant results confirm those obtained on the smaller laboratory and bench scales of experimentation.

Jan 1, 1979

Since 1955 Gaspe Mines has produced 144 million tonnes of ore, averaging 0.87% Cu, mined from two open pits and underground workings. In 1994, four exploration drill holes discovered a buried porphyry/skarn Cu-Mo deposit at depths of between 1000 m and 1700 m below the top of Porphyry Mountain. The mineralization and alteration associated with the Porphyry mountain quartz monzonite does not outcrop. A total of 19,500 m of drilling in 12 drill holes has outlined 200 million tonnes grading 0.73% Cu and 0.08% Mo. Mineralization occurs as veins and disseminations of chalcopyrite and molybdenite. Drilling and feasibility studies continue.

Jan 1, 1998

By C. Bazin, B. Girard

The application of time series analysis techniques to plant data provides a method for examining and modeling the behavior of operators during the operation of furnaces for the reduction of ilmenite concentrate. The obtained model is used to assess the consistency of actions carried out by the operators and to review and improve the training procedures.

Jan 1, 1996

By J. D. Miller

Fluid flow phenomena and therefore the flotation efficiency of air-sparged hydrocyclone (ASH) flotation are strongly dependent on operating and design variables such as air and slurry flow rates, underflow and overflow opening areas, percent solids of the feed, reagent levels, particle size and ASH length. Time-averaged multiphase flow characteristics, as determined by X-ray CT (described in a previous publication), are used to understand and explain the steady-state ASH flotation of quartz. A detailed parametric study of quartz flotation by a nominal 2in. diam. air-sparged hydrocyclone (ASH-2C) revealed the influence of these variables on the flotation response, which is discussed in terms of the multiphase flow characteristics. Thus, a phenomenological description of quartz flotation has been established to assist in the further development and utilization of the ASH technology.

Jan 1, 1996

By V. M. Torres

Arapiraca ore deposit has a mixed chalcopyritelbornite mineralogy, with a copper head grade of 0.7%. The reserve size does no allow profitable exploration by grinding/flotation. The technical feasibility of exploring the reserve by heap leaching was studied. Preliminary agitation tests indicated 85% copper recovery. To simulate heap leaching, column tests were performed. The tests included different ore types and acid addition levels. Operating at pH range 1.6-1.8, 67% copper extraction was achieved. Also, it was found an empirical correlation between the operation pH range, copper extraction and acid consumption.

Jan 1, 1996

By B. Denby, R. Hollands

Mine information is often multi-disciplinary, dynamic and spatially complex. Different departments use the same data in many different ways, information changes over time and mines change their shape continuously. Earthworks InTouch is a radical VR-based system developed by AIMS Solutions and marketed by Earthworks, which provides a rapid and intuitive interface to a wide range of mine information. VR is used to provide an interactive and visually accurate, dynamic 3D model of the mine workings and equipment operating in the mine. Individual objects in the mine can be linked to external applications that provide up-to-date and context sensitive information. Equipment movement can be simulated or tied in to real-time survey from GPS systems for example or excavator productivity data can be extracted from a production database. The paper will highlight the major advantages of using such a VR interface to access valuable and time sensitive information.

Jan 1, 2002

By George P. Demopoulos, Vladimiros G. Papangelakis, Dimitrios Filippou, A. J. Monhemius, G. W. Warren, E. Peters

A new method developed for the estimation of the activity of Ht in mixed sulfate solutions is described and examples of application of this method to the system H2SO4-ZnSO4-FeSO4-Fe2(SO4)3 from 298 to 473 K are offered. The method makes use of an "extended Debye-Hiickel" type of equation that was originally put forth by Das for pure H2SO4 solutions at ambient temperature. The treatment of mixed sulfate solutions was made possible by combining that equation of Das with a speciation algorithm which calculates the abundance of all species formed. The developed method, which also takes into account ionic strength and temperature effects, was used to generate hydrogen ion activity and speciation data for all possible acid/metal sulfate pairs of the system H2SO4-ZnSO4-FeSO4-Fe2(SO4)3. Finally, under the light of the reported data, specific examples of hydrometallurgical reaction systems are analyzed in terms of thermodynamics or kinetics. In particular, the systems discussed are: hydrometallurgical precipitation of hematite, solvent extraction of Fe(III), acid leaching of zinc ferrite, and oxidation of Fe(II) to Fe(III) by O2(aq).

Jan 1, 1993

By P. Zhang

The Crago “Double Float” process is widely used in upgrading phosphate ore. This process is inefficient, as it floats about 30-40% of the sands in the flotation feed twice and requires a deoiling step. This paper summarizes several research projects on improving phosphate flotation. The University of Utah investigated a new flotation chemistry for efficient flotation of phosphate in a single step. The Florida Institute of Phosphate Research developed several single-collector, all-anionic flotation flowsheets using various sizing schemes. In addition, Eriez invented the HydroFloat separator, which demonstrated great potential for processing coarse flotation feed in one step.

Jan 1, 2004

By K. J. Reid

A historical background of the development of automated material balance packages is presented including a summary of currently available packages and a description of the present work at the Mineral Resources Research Center of the University of Minnesota. A brief mathematical statement of the problem is given and solution techniques discussed. The problems and difficulties normally associated with material balances, both hand calculated and computer calculated are described. Several aspects of the available material balance packages as related to the "user/computer" interface are evaluated in detail. Elements of the material balance packages that affect the solutions are examined and the relative performance of the main packages on specialized problems presented. Finally, areas associated with automated material balances that require further work before computer packages can be widely used in industry are outlined.

Jan 1, 1982

By William J. Attwooll

The development of gold heap leach projects in the Cripple Creek, Colorado, mining district has required utilization of heap leach pad sites other than relatively level natural ground. This paper describes the construction of a heap leach pad adequate to accommodate 907,000 tonnes (1,000,000 st) of ore over the surface of a tailings pond constructed during previous milling activities at the site. Based on the design parameters and the observed behavior to date, it has been found feasible to construct a major heap leach pile on the surface of a conventional tailings pond.

Jan 1, 1987

By L. Patts, J. Hummer

The use of diesel-powered equipment in underground coal mines has increased substantially during the last ten years in an effort to enhance mine safety and productivity. Pennsylvania and West Virginia are two of a number of states with regulations governing the use of such equipment. These states both developed and promulgated regulations before permitting diesel equipment in their underground coal mines because of concern for miners’ safety and health, especially with regard to the contamination of mine ventilation air with diesel exhaust emissions. The major components of diesel exhaust emissions are combustion gases and diesel particulate matter. The gaseous emissions consist of carbon monoxide, carbon dioxide, oxides of nitrogen, sulfur oxides and unburned hydrocarbons. The diesel particulate matter (DPM) is comprised of solid carbon particles, liquid and solid hydrocarbons, sulfates and moisture. The Federal Mine Safety and Health Administration (MSHA) also promulgated regulations in an effort to control diesel emissions in underground coal mines. MSHA has adopted threshold limit values (TLVs) for all gaseous components of diesel exhaust, which were established by the American Conference of Governmental Industrial Hygienists (ACGIH). MSHA (30 CFR Part 72 Subpart D) has established a tailpipe DPM emissions limit of 2.5 g/hr for diesel engines used in permissible equipment, heavy-duty non-permissible equipment, generators and compressors used in underground coal mines. A tailpipe DPM limit of 5.0 g/hr has been established for light-duty outby diesel-powered equipment. The rationale for the tailpipe emissions limit was that an ambient measurement of DPM in a coal mine was not feasible because there is no established sampling method able to distinguish between coal mine dust and DPM. The stringent tailpipe emissions limit mandates the use of exhaust aftertreatment devices for most diesel engines used in underground coal mines today. One method by which tailpipe DPM can be reduced to MSHA limits involves using an exhaust cooling device in conjunction with a high-temperature, disposable diesel particulate filter.

Jan 1, 2011

By S. Chander

The effect of pretreatment potential on the response of a gold electrode for Eh measurements in sulfide solutions was examined in terms of measured Eh values and electrode response time. The electrode response time is defined as the time required for the electrode to reach a steady-state value. The relationship between measured Eh values and the hydrosulfide ion concentration is established. The effect of pH, the reversibility of the gold electrode in the sulfide solutions, and the reproducibility of measurements are also investigated. A mixed potential theory is proposed to explain the observations.

Jan 1, 1989

By F. F. Aplan

Rather than reiterate what is well known about the flotation of the non-sulfide minerals, emphasis has been placed on those separations which are not so effective. These difficult separations are largely connected with problems of selectivity in the flotation of the base metal oxides, the other slightly soluble minerals, the insoluble oxides and the naturally floatable minerals. The paper discusses possible methods of improving selectivity between similar species and of improving selectivity against the gangue minerals.

Jan 1, 1994

By Fred N. Kissell, Jeffery L. Kohler, Edward D. Thimons

Aerodynamic stall of vane-axial fans is both an operational problem and a safety concern. While deep stall is relatively easy to detect, the diagnosis of a partial stall is often more difficult. Its transient nature and the fact that its symptoms can mimic electromechanical problems of the fan and fan drive assembly, or vice-versa, compound the difficulty of making a timely and accurate diagnosis. A knowledge-based expert system known as FANPRO has been developed to aid in the diagnosis of these problems. FANPRO and its application are the subject of this paper.

Jan 1, 1991

By Ryan Lemmon

Belt turnovers are commonly used in conveyors to rotate the belt so that the clean side of the belt contacts the return idlers. The belt turnover length has traditionally been sized on only the twisting stresses. However, belt turnovers are also subjected to bending stresses due to the weight of the belt. Although bending stresses have in the past been ignored, these stresses are significant and should not be neglected. This paper quantifies and presents a method for calculated twisting and bending stresses and also the belt sag.

Jan 1, 2002