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By William J. Ferguson

At Henderson Operations the 24-kilometer conveyor system consists of three main conveyors with lengths of 1.2 km, 16.7 km and 6 km. Upon commissioning of the conveyor system, the Henderson maintenance department was challenged with the inspection and monitoring of over 50,000 idlers. To take a proactive approach to idler maintenance, an idler tracking database system was developed. Using the idler tracking program, the Henderson Crush & Convey department now has the ability to provide data for engineering solutions to idler problems and to manage thousands of idlers for priority replacement work and warranty purposes. Recognizing the potential for injury to Henderson employees in the process of idler handling, Henderson approached idler replacement as a material handling process. Material handling solutions have resulted in failed idlers being replaced and discarded from the underground environment without ever touching a human hand. This paper will detail how Henderson tracks idlers in all primary conveyor belts and how an innovative idler handling system can result in reduced risks to conveyor maintenance employees.

Jan 1, 2004

By Charles C. Y. Chen, Duane R. Skidmore

Batch leaching of Ohio #1, Ohio #4A and Ohio #5 coals was conducted with the thermophilic. sulfur, oxidizing microorganism: Sulfolobus acidocaldarius. Four different size fractions of each coal, with median sizes of 508, 200, 90, and 49 microns, were subjected for 10 days to leaching in a 5% coal-water slurry at 72°C and a pH of 2. Release rates and extent of sulfate and iron I1 and I11 ions from the coals during the leaching process and distribution of sulfur forms (sulfate, pyritic and organic) in the coal samples before and after treatment were determined. Data indicated that Ohio #1 coal, with an initial sulfur content of 0.6%, showed no significant changes with leaching in total sulfur content or forms of sulfur. The Ohio #4A coal, with initial total sulfur content near 5%, yielded product, for sizes below 200 microns with 90% reduction of pyritic sulfur while the extent of organic sulfur removal varied with coal particle size. Results similar to those for Ohio #4A were observed on the Ohio #5 coal, which had an initial total sulfur content of 3% and a final sulfur content near 1%. The findings were interpreted in terms of basic biological, chemical and physical mechanisms.

Jan 1, 1989

By P. Jacquin

Many a deposit estimation has been carried out since geostatistical methods were first implemented. To date however few mining programs have totally been completed and even fewer comparisons can be drawn between estimated reserves and extracted ore tonnages. Aluminium Pechiney work a number of bauxite mines in Southern France. As from 1969 they modified their deposit estimation methods, giving up traditional approaches and opting for geostatistics. At that time, the authors of this paper were entrusted with the first geostatistical estimations and in particular, those concerning the deposits mentioned herein. Over the past decade a number of deposits have been worked out and we thought it interesting to report about comparative results. French bauxite deposits are of the karstic, as opposed to the lateritic, type. The bauxite, formed at some distance of the present-day deposit, was brought to and trapped in limestone karst pits. Subsequent physical and chemical alterations may have taken place : silica and carbonate drifts, recent karst slips. The morphology of these deposits is often rather complicated. The deposits are small from a few hundred thousand to a few million tons at the most. The overburden thickness usually precludes open mining. Mining investments and financial risks are often high, making it necessary to obtain optimal information on the deposit considered for mining. For the three cases brought up in this paper, deposit sizes, exploration methods and conclusions differ. They are brought up mainly to show the advantages inherent to a quality geostatistical study and the lessons drawn by Aluminium Pechiney.

Jan 1, 1982

By John C. Nichols

The Ouachita, Ozark-St. Francis, and Mark Twain National Forests are located within the Ozark and the Ouachita Mountains regions of southern Missouri, central and northern Arkansas, and eastern Oklahoma- an area generally referred to as the Ozark-Ouachita or Interior Highlands. These national forests share many similarities in geography, biotic resources, and areas of shared public, market, and user interests. The three national forests have joined together to evaluate the natural resources within the Highlands and to study the impacts of the forests on local and regional economies and on the people who use these national forests and their resources. Other federal, state, and local government agencies and universities have joined with the Forest Service in this project, broadening the assessment area beyond the national forest boundaries to include 107 counties in Arkansas, Missouri, and Oklahoma. The diverse, resource-related data for the as- sessment area address social, economic, terrestrial, and aquatic issues and conditions throughout the Highlands. The assessment report currently is being developed by the Forest Service and will include an accoMpanying CD-ROM. The Ozark-Ouachita Highlands assessment has provided a forum for minerals- and geology-related resources, industries, social significance, and potential to be profiled and discussed along with other critical assessment resources. The state geological agencies in Arkansas, Missouri, and Oklahoma were active contributors to this effort. Their reports and other key data bases developed and used for the minerals sections of the published assessment report will be available either as a supplemental CD-ROM or on the Internet. Updated information on the progress of the assessment report can be found at the Ouachita National Forest Website, at <http://www.fs.fed.us/oonf/ouachita.htm>. This will also include a matrix displaying the minerals in the assessment area, their occurrence by assessment-area counties, and a potential ranking, as well as information on interesting geologic features. The state and federal reports, resources, and data bases, have helped answer key questions concerning mineral resources and related issues in the Highlands:

Jan 1, 1999

By B. Campbell

This paper will detail the successful construction methods of a 20- foot diameter wet well shaft, approximately 180 feet deep in overall depth and 150-feet below the water table, adjacent to Lake Nacimiento, in San Luis Obispo County, California. In addition to this, highlights will include the selection process in determining the most economical support of excavation, while minimizing risk of large water inflows as indicated in the Owner?s Geotechnical Baseline Report (GBR).

Jan 1, 2010

By Tony Treasure, Ian Ewart

The EMEW® cell has been developed to overcome a number of inherent limitations in conventional electrowinning technology, particularly the high cost and restricted process windows characteristic of conventional hardware. The EMEW technology has been widely demonstrated to achieve high performance for various metals under chemical conditions well outside the limits required for efficient operation of conventional cells. In particular application of the EMEW cell for recovery of silver offers significant operating and capital cost advantages over conventional Merrill Crowe technology used for cyanide based solutions. The cell also offers process advantages for direct silver recovery from nitric acid solutions. The performance of the EMEW® cell on silver cyanide solutions, producing high grade silver metal in a single step, is accomplished by providing a physical mechanism which presents metal ions to the cathode on a highly efficient and continuous basis. The simplicity of design and operation of the EMEW cell offers the following advantages for silver recovery from cyanide or nitrate based solutions: • High grade product in a single step. • Selective for silver over other metals in the electrolyte. • Wide operating concentration range (100,000 - 5ppm). • Ability of the cell to operated in a variety of acid or alkaline electrolytes. (Cyanide, Nitrate). • Simple liquor reticulation. • No pretreatment required - Clarification, deaeration or zinc dust. • High cmTent density and current efficiency compared to conventional electrowinning cell. • Modular design allows for flexible operation and production rate. • Pilot plant results using full scale cell result in accurate scale up design. • Easy/fast installation - cell banks are delivered pre configured with piping and wiring. • Enclosed cell minimizes corrosive vapor and liquid losses in the circuit.

Jan 1, 2000

By M. K. Gangal, E. D. Dainty

The paper describes the use of portable aerosol monitors in determining real-time concentrations of diesel soot and respirable total dust in dieselized mines. The field studies were conducted in a simulated diesel environment in the laboratory where no other type of dust was present, and in four underground mines with multi-diesel machine operations. Two packages for the real-time monitoring of diesel soot were prepared which included two types of aerosol monitors: a Miniram, model PDM-3, and a Sibata, model PDS-1. These monitors utilize the principle of light-scattering to measure the airborne mass concentration in the environment. The monitoring device results were compared against the Time-Weighted-Average (TWA) values produced by the gravimetric filter sampling method, permitting calibration factors to be determined for each field test. Both instrument packages provided comparable results. The instrument calibration factors varied for different tests, which may be due to different material composition, particle size distribution, density and shape of the aerosols. This approach for real-time determination of diesel soot is found to be simple, inexpensive and easy to use. More field tests for diesel soot determination and further research on size distribution of particulates in dieselized mines are required.

Jan 1, 1989

By Malcolm J. Lake, P. Brad Marchant, Linda M. Broughton

Thiourea is recognized as a technically competitive alternative to cyanide for gold and silver extraction for a variety of ores and concentrates. This paper describes the results of a recent mini-pilot locked cycle test comparing cyanidation with acidothioureation treatment of gold bearing sulphide concentrate. The gold extractability of both methods was similar. The comparative metallurgical operating conditions and test results are summarized. Detailed byproduct solution analyses and environmental toxicity test results are presented and suggest that thioureation might result in acutely toxic byproducts even after treatment. Comparative process economics are summarized based on preliminary commercial operating flowsheets derived for the locked cycle case study. Capital and operating cost estimates are shown. The results indicate that cyanidation is more economically favorable within the constraints of the case study. Considerations for process selection between thioureation and cyanidation, for conceptual case studies, are discussed.

Jan 1, 1998

By F. W. De Vries

A review as of the date of this meeting will cover the writer's perception of eachof the areas indicated in the charts. Changes in many are occurring with enough frequency that a detailed summary would be inaccurate within a few days of writing; for this reason, only an outline is appropriate for advanced preparation.

Jan 1, 1998

By V. Fred Swanson, J. Patrick Glynn

The environment for process engineers today is very different from 20 years ago. The ideas and mathematical description of models for a multitude of different unit operations is an ongoing development. The computer tools to deal with the mathematics are readily available and specialist companies have developed, tested and verified their models. The challenge for the process engineer is to know which package to use and to know whether a particular application is the most accurate for the specific process. Metallurgical simulation programs today are well known and proven. Certain programs are specialized while others are broader based. The needs of each user are dependent on the application. Typically, most users require the following operations: • Comminution • Flotation • Hydrometallurgy • Pyrometallurgy • Additional requirements could be defined as: • Thermodynamic capabilities for solids, phases, and gases • Dynamic simulation • Data analysis tools • Coal oriented operations • Diamond oriented operations

Jan 1, 1997

By M. M. Nash

Since the late 19th Century, scholars have been concerned about finding proper methods of managing business. The search seems to be taking us full-circle to the time and motion studies of Taylor (Horn, 1987). It wasn&apos;t until the late 1970&apos;s, however, that systematic investigations were made in the mining industry. One of the first was a study by Sanders, Patterson, and Peay (1976). That project explored the relationship of attitudes and safety. Peay, Atkin, and Goodman (1977, then reviewed the whole area of Organizational Development, including the so-called Rushton experiment.

Jan 1, 1988

By N. R. Joshi, A. D. Agate

It is estimated that more than 80% of phosphate rock output in the world is used for fertilizer production. In India, there are only a few high-grade deposits of phosphate ores; therefore, most of the requirement for phosphatic fertilizers is satisfied with imported DAP (diamino phosphoric acid). Due to the drain on foreign exchange reserves, this import-dependent, essential commodity is in short supply in India and, therefore, is sparingly used by farmers. In addition, of the added phosphorus, normally 80% becomes unavailable to plants because phosphorus complexes are formed in soil, causing deleterious effects on plants. In our laboratory, this problem was tackled by using a bacterial consortium of phosphorus-solubilizing bacteria. It resulted in the speeding up of seed germination and increasing available phosphorus in the soil by 14%, over a period of 80 days. To use the low-grade deposits of phosphatic rocks available in India near Hirapur, Madhya Pradesh, India, which contain high amounts of iron, beneficiation through microbial means was used for phosphorus removal. Beneficiation was achieved partially through removal of extra iron by oxidizing ferrous iron from the ore by a Thiobacillus species after removal of impurities containing both silica and iron, instead of sieving and cleaning the ore using different techniques. This resulted in a cleaner ore, with nearly 70% of such impurities removed. The factors for beneficiation technique were standardized at the laboratory level and are being used for scaling up of the process. Thus, the beneficiation of phosphatic rock from Hirapur will be an important first step of phosphorus production in India.

Jan 1, 1999

By Joseph M. Denk, John N. Baran, William J. Francart

Filling or sealing shafts of underground coal mines is required when the mine is declared inactive by the operator, permanently closed or abandoned for a period of time greater than 90 days. Although shaft filling requires the use of incombustible materials for the first fifty feet of the shaft, a sparking potential may exist which has been reported to be the cause in at least one shaft-filling explosion. This paper outlines the method used at the explosion site to monitor mine gases within the shaft to assure the safety of the workers involved in the remainder of the shaft-filling operations. Gases which were monitored include methane, oxygen, carbon monoxide and carbon dioxide. Continuous sampling was conducted twenty-four hours per day to determine the methane liberation and accumulation of gases within the shaft. Once gas concentrations were evaluated, the need for ventilation in the shaft was obvious because methane accumulations within the shaft were in the explosive range. Several methods to ventilate the shaft were explored. The most practical seemed to be the dilution of gas concentrations with compressed air to inject a quantity of fresh air into the shaft. But, when the compressed air was stopped, a buildup of an explosive mixture reoccurred. The pattern of gas accumulation was then studied to find the correct combination of ventilation and shaft-filling time periods which would a1 low for the greatest reduction of the potential for an explosion. Gas concentration sampling continued during the remainder of shaft-filling operations at this shaft and four others at the same mine. In conclusion, this paper illustrates some of the problems which are often overlooked in a shaft-filling operation. If addressed, the work can be done in a safe and feasible manner.

Jan 1, 1987

By T. Gouri Charan, G. V. Rao

A spherical agglomeration process for the separation of scheelite fines of less than 30 µm in very low concentration of 0.04% WO3 in a binary mixture with quartz fines of less than 30 pm has been described. A concentrate containing 14% WO, with more than 90% recoveries could be achieved by means of anionic sodium sulfo succinate collector at pH 3.5 and also with commonly used anionic sodium oleate at pH 10.5 as per the conceptual flowsheet suggested. Such a process is envisaged as commercial potential for the recovery of fine-grained scheelite present in the tailings of gold plants as found in India.

Jan 1, 1991

By R. Cooper, K. De Wet, A. Janwong

"Horsehead Metal Products is a zinc refinery in Mooresboro NC treating crude Waelz Oxide (WOX) to produce Special High Grade Zinc by a hydrometallurgical process, comprising leaching, zinc solvent extraction/electrowinning (SX/EW), melting and casting and bleed treatment. Cadmium removal by zinc dust cementation plays an essential role in the bleed treatment circuit to prevent a build-up of cadmium in the circuit. Silica, although not present at significant levels in the WOX feed material (approximately 0.3%), had a significant impact on the efficiency of cadmium cementation with zinc dust, most likely due to the passivation of zinc dust particles with silica gel. Solid/liquid separation efficiency by filter press was also impacted. The silica levels were mapped throughout the circuit in an attempt to identify the source of the silica issues. Adjustments including using PLS as feed to cementation, pH control in WOX leaching and neutralization have been introduced to mitigate the issues created by silica gel in the circuit. INTRODUCTION Located in North Carolina, Horsehead Metal Products Inc. is a hydrometallurgical zinc refinery processing Waelz Oxide (WOX) to produce Special High Grade (SHG) zinc. The flowsheet, known as the Modified Zincex® process, consists of leaching, solvent extraction, electrowinning, melting and casting and bleed treatment as illustrated in Figure 1. Cadmium cementation, part of the bleed treatment process, provides an essential bleed of cadmium from the circuit, as metallic cement. The Cadmium cementation circuit consists of agitated cementation reactors, a zinc dust addition system, filter presses, agitated purification (releach) reactors and a cadmium concentrate filter press Silica can be found in several forms in acid leaching. The first form is fine silicate particles. The size of the particles can vary from one to twenty microns (1). Fine silicate particles can lead to the formation of crud in solvent extraction circuits (2, 3). At Mooresboro, crud has been observed in Depletion, which is part of the solvent extraction circuit. Silica content in the solution in this section is high. The second form of silica is monosilicic acid Si(OH)4, which begins to polymerize almost immediately upon being leached into solution. Monosilicic acid polymerizes to silica gel or a silica precipitate dependent primarily on supersaturation (5). Factors that influence the rate of polymerization include temperature, sulfuric acid concentration / pH, hydrofluoric acid concentration, seeding, and dissolved salts concentration such as zinc and aluminum in the solution (4, 5, 6). In sulfate systems, silica solubility is reported in the range of 150 to 450 ppm of SiO2 (3, 5, 7)."

Jan 1, 2016

Controlled-blasting experiments in small development drifts were conducted at CANMET&apos;s Experimental Mine in 1992 and 1993. The objective of these experiments was to develop suitable controlled-blasting techniques for small development headings that are drilled by jackleg with 32-mm-diam holes. The experimentation was also aimed at providing insight into blast-damage mechanisms. Particular attention was given to the physical-mechanical properties of the rock and the rock-mass structural data. The drift faces were approximately 2.4 by 2.4 m (7.9 x 7.9 ft) in size with 36 to 43 holes drilled to a depth of 2.4 m (7.9 ft). Cartridged water gels, emulsions and semigelatin dynamite were used in the cuts and as primers, ANFO was used as the main explosive and decoupled 19-mm (0.75 in.) diam semigelatin dynamite charges were used in the perimeter holes. Smooth-blasting techniques and presplitting were tested in the underground mine. All of the blasts were monitored with a multichannel blast-vibration monitor, to which was attached sets of high frequency geophones and accelerometers. These experiments demonstrated the efficiency of controlled-blasting techniques for the reduction of blast damage and also demonstrated the need to improve the safety and efficiency of using explosives.

Jan 1, 1997

By J. Simmons, P. Ziemkiewicz

Acid-Base Accounting (ABA) is an analytical procedure that provides values to help assess the acid-producing and acid-neutralizing potential of overburden rocks prior to coal mining and other large-scale excavations. This procedure was developed by West Virginia University scientists during the 1960s. After the passage of laws requiring an assessment of surface mining on water quality, ABA became a preferred method to predict post-mining water quality,and permitting decisions for surface mines are largely based on thevalues determined by ABA. In order to predict the post-mining water quality, the amount of acid-producing rock is compared to the amount of acid-neutralizing rock, and a prediction of the water quality at the site (whether acid or alkaline) is obtained. We gathered geologic and geographic data for 56 mined sites in West Virginia, which allowed us to estimate total overburden amounts, and values for maximum potential acidity (MPA), neutralization potential (NP), net neutralization potential (NNP), and NP/MPA ratios for each site based on ABA. These values were correlated to post-mining water quality from springs or seeps on the mined property. Overburden mass was determined by three methods, with the method used by Pennsylvania researchers showing the most accurate results to actual overburden mass. A poor relationship existed between MPA and post-mining water quality, NP was intermediate, and NNP and the NP/MPA ratio showed the best prediction accuracy. In this study, NNP and the NP/MPA ratio gave identical water quality prediction results. Therefore using NP/MPA ratios, values were separated into categories: <1 should produce acid drainage, between 1 and 2 can produce either acid or alkaline water conditions, and >2 should produce alkaline water. On our 56 surface mined sites, NP/MPA ratios varied from 0.1 to 31, and six sites (11%) did not fit the expected pattern using this category approach. Two of eight sites with ratios <1 did not produce acid drainage as predicted (the drainage was neutral), and four of 40 sites with a ratio >2 produced acid drainage when they should not have. These latter four sites were either mined very slowly, had non-representative ABA data, received water from an adjacent underground mine, or had a surface mining practice that degraded the water. In general, an NP/MPA ratio of <1 produced acid or neutral drainage sites, between 1 and 2 produced mostly alkaline drainage sites, while NP/MPA ratios of >2 produced alkaline drainage with a few exceptions. ABA is a good tool to assess overburden quality before surface mining and to predict post-mining drainage quality after mining. The interpretation from ABA values was correct in 50 out of 52 cases (96%), excluding the four anomalous sites, which had acid water for reasons other than overburden quality.

Jan 1, 2003

By Lee W. Abramson, James E. Crawley

Caltrans is studying alignments for a 160-kilometer-long high speed ground transportation system from Los Angeles to Bakersfield across the Tehachapi Mountains. This link is needed to connect southern California with San Francisco by a short passenger rail service. None presently exists. The system will require tunnels and viaducts along the route with sections crossing two major active fault zones. High speed ground transportation technologies are being evaluated for achieving rail speeds of between 200 and 480 kilometers per hour. This paper presents the technical requirements for tunnels along the alternative routes being considered for the project.

Jan 1, 1995

By G. Bloomsburg, R. E. Williams, S. D. Vincent

A modeling scheme is developed to simulate the hydrogeologic effects of mine design and development in unsaturated rock. Simulations are conducted using the UNSAT2 finite element computer program and hydrogeologic data from the site of a proposed mined-out waste repository at Yucca Mountain, NV. Results of the simulations are analyzed for: •variations in the direction of ground water flow and in the distribution of pressure head caused by the design of the mined out openings; and •mine design variables that affect the predicted rates of mine water inflow. Evaluating the hydrogeologic impacts of mine design and mine development in unsaturated rock is significant in several respects. Characterization of the preemplacement of wastes along the fastest path ground water flow system at the Yucca Mountain site has been a primary research effort. Ultimately, however, the degree to which waste isolation is achieved will depend largely on the post-mining hydrogeologic environment as altered by the mine design and on the radionuclide inventory and resulting heat effects of the repository. Therefore, an ongoing characterization of the proposed mined-out nuclear waste repository at Yucca Mountain, NV, is recommended. Modeling results indicate that: •mined out openings will affect the movement of ground water, both in rate and direction; •hydraulic effects of mine development depend on the hydrogeologic environment and on mine design geometry; •mine water inflow is possible in the unsaturated zone, even for mines developed in hydrogeologically homogeneous rocks; and •mine water inflow can occur at values of down ward flux that are appreciably less than the saturated hydraulic conductivity of the overlying rocks.

Jan 1, 1991

By Robert K. Towner, Francis S. Kendorski

Shotcrete drift linings at the Climax Mine of the Climax Molybdenum Company have undergone four years of extensive evaluations as a replacement for thick poured-in-place concrete linings. Any drift lining at Climax must be able to withstand the rigors of undercut and secondary blasting, weight problems induced by panel caving, and the abrasion of slusher mining. Examined here are the conclusions reached so far on shotcrete drift linings which have not yet completed the approximately six-year cycle from development to ore exhaustion. Properly applied shotcrete is an adequate drift lining for all phases of the Climax panel caving system of mining. Undercut blasting will damage shotcrete unless blasts are correctly timed. Weight problems will destroy shotcrete drift linings as efficiently as it will destroy concrete or steel support systems. Abrasion and secondary blasting results are inconclusive as the shotcrete lined slusher drifts have not entered the ore production stage of the mining cycle. In addition to drift linings, Climax has found shotcrete to be invaluable for lining large underground shops, for temporary support systems, for permanent ventilation bulkheads and for the repair of abraded or weight damage concrete lined slusher and haulage drifts.

Jan 1, 1974