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By R. Larry Davis

Over the past decade there has been a continual decrease in domestic oil reserves accompanied by a sharp increase in the demand for energy. Even with increased imports of foreign oil, the energy demand has not been met. This has forced many users to turn to substitute fuels. Of the many substitute fuels available most users are turning to and creating an increased demand for low sulfur coal. Because of the increased demand for low sulfur coal as well as the inherent problems in producing eastern coal, many producers have turned their attention to the large deposits of low sulfur coal in the western United States. Western coal mining is, however, not without its problems such as high moisture content, high ash content, highly variable sulfur content, multiple seams, and/or pitching seams. It is to aid in the solution of these problems that this chapter is directed.

Jan 1, 1979

By R. S. Austin

One-third of the world's and most US kaolin is produced from Late Cretaceous and Early Tertiary sedimentary strata in Georgia and South Carolina. The kaolin is part of a belt extending to Arkansas of aluminous lateritic deposits, including bauxite. Original sediments were profoundly altered by chemical weathering during Early Tertiary time. Mining exploits those uncommon deposits where extreme leaching and chemical recombination have produced a clay of nearly pure mineral kaolinite. Properly selected and refined, kaolin is an important pigment, filler, extender and chemical compound in the paper, paint, plastics, ceramics and catalyst industries.

Jan 1, 1998

By D. G., Bosse&apos

Equipment choices for ultrafine grinding encompass several different types of dry and wet size-reduction devices. These need to be put into functional perspective for systematic analysis of capabilities and limitations versus processing requirements of the materials to be satisfactorily ground. Particle strengths plus maximum and average sizes are the primary variables controlling grinding action requirements and equipment options for efficient processing. These are fairly well understood and provide the starting point for decisions. Particle space requirements under dynamic processing conditions vary with particle shapes and size-distributions by as much as 30X. This additional major variable is not widely appreciated and does need adequate description to provide a firm basis for selecting processing compositions and procedures.

Jan 1, 1983

By Donald Ross-Watt

Mining project investment concerns the installation of mine capacity for the purpose of generating a stream of future economic benefits. In order to make this type of investment decision, the optimum specifications for the project must first be determined. Then, the economic justification of the investment tin be evaluated based on these specifications. Economic evaluation to guide mining project investment decisions is based on a proposed plan for mining the deposit over its operational life. If single point estimates are made of deposit characteristics and environmental parameters* as the basis for assessing a future stream of economic benefits associated with the investment, a future mining-plan can be optimally fitted to these estimates and, to the extent that such estimates are actually realized, this plan will retain optimality.

Jan 1, 1979

By Rajiv Hadkar, M. D. McKinley, J. B. Hiskey, B. J. Scheiner, G. W. Warren

Flyash from municipal solid waste incinerators containing roughly 13 to 15% Zn, 2% Pb and 0.2% Cd is an attractive material for simultaneous metal recovery and detoxification. Results have shown that Pb in flyash is present as PbSO4 and PbC12 and that about 70% of the Zn is present in the form of soluble amorphous compounds. Leaching results in a number of acid and basic lixiviants show that acid leaching is clearly more effective than basic leaching which is limited by low solubility of Cd and Zn. Cementation in acid solution with pH < 1 promotes redissolution of the precipitated metal. Successful zinc electrowinning from chloride leaching solutions has also been demonstrated, although Pb2+ and Na+ can be potentially detrimental. The presence of Pb2+ can prevent deposition of metallic Zn, forming zinc oxychloride, ZnC12.4Zn(OH)2, instead. High concentrations of Na+ can also result in precipitation of NaCl. This investigation has shown that hydrometallurgical treatment of MSW flyash through leaching, cementation and electrowinning is a potentially feasible method for simultaneous detoxification and recovery of metal values. Several issues have also been identified which would require further investigation for final process development.

Jan 1, 1993

By Keith G. Wallace, Justus B. Deen, Daniel J. Brunner

This paper describes the impact of natural ventilation pressure (NVP) on the Nuclear Waste Isolation Pilot Plant in New Mexico (WIPP). The WIPP site is a U.S. Department of Energy underground facility for the disposal of low level radioactive transuranic defense generated waste. Because the facility is designed for the storage of nuclear waste, special design considerations are necessary to ensure containment of potential radioactive releases. The main design considerations which influence the ventilation system are the requirements of separate air splits for mining and storage operations and of air filtering before atmospheric discharge in the event of a radioactive release. The leakage between the two air splits must always be from the mining area to the storage area. The transient effects of natural ventilation pressures, caused by seasonal and diurnal surface temperature changes, impact the ventilation characteristics throughout the facility. This paper discusses the measurements taken to quantify the changes in NVP and the engineered systems designed to mitigate against the effects of NVP.

Jan 1, 1991

By Winfield G. Wright, Greg P. Meeker, Philip L. Verplanck, Douglas B. Yager, Dana J. Bove, M. Alisa Mast

A really extensive acid sulfate-altered and mineralized rock in the southeast Red Mountains area is noted for its association with naturally occurring and mine-related acidic and metal-rich waters. Integrated geologic and aqueous geochemical studies demonstrate that the degree of metal mobilization and acid production in natural waters correlates well with the type of hydrothermally altered rock and structural features in which these water interact. Quartz-sericite-pyrite, quartz-alunite, and argillic alteration assemblages are associated with some of the most naturally acidic, high-metal waters in the study area; calcite-bearing propylitic rocks are related to the most pristine waters and buffer sulfate-rich, acidic waters produced by pyrite oxidation. Trace metals in natural waters are mostly derived from enargite, zinc-rich tetrahedrite and sphalerite. Pyrite oxidation contributes very little with respect to base-metals in these natural waters.

Jan 1, 2000

By V. T. McLemore

Rare earth elements (REE) are becoming more important in our society. REE deposits are found throughout NM. Some REE past production (1950s), as bastnaesite, came from the Gallinas Mountains district, Lincoln County, NM. Several companies and the U.S. Bureau of Mines (USBM) have conducted exploration programs to identify REE potential. Four types of deposits are found in the district: epithermal REE-F veins, Cu-REE-F veins, REE-F breccia pipe and iron skarn deposits; all are associated with Tertiary peraluminous, alkaline to alkalic-calcic volcanic rocks. District zonation is defined by base metals (REE-F-Cu veins) that form center of the district, surrounded by REE-F veins. The magmatic-hydrothermal breccia pipe deposits form a belt partially surrounding the veins. Iron skarns formed at the top and edge of the trachyte intrusion and are likely the earliest stage of mineralization. In 1991-1992, USBM calculated an inferred resource of 0.487 million metric tons with a grade of 2.95% total REE. With the projected increase in demand of REE, areas such as the Gallinas Mountains district in New Mexico are being re-examined for additional REE potential.

Jan 1, 2011

By M. Beus, S. Stewart, S. Iverson

Recent ore pass failures have underlined the need for improved designs, standards, structural monitoring methods and better hang-up prevention and removal techniques. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) are investigating methods to improve safety during the transport of ore in ore passes. Design criteria and hang-up prevention and remediation strategies involve studies of the effects of static and dynamic ore and waste-rock loads on chutes, walls, gates and support structures. Particle flow analysis methods were used to simulate the response of various ore pass designs to a wide range of ore loading conditions. A full-scale mockup of actual ore pass and chute assemblies was duplicated and tested for load response. Data from a particle flow code and the mock-ups were compared Loads on an active ore pass chute were measured

Jan 1, 2000

By H. J. Marais, P. C. van Aswegen

The Biological Oxidation (BlOX®) Process for the treatment of refractory gold ores was commercialized in 1988. During the last decade, the technology has developed into a mature, commercially viable process, with five additional operations commissioned, including operations at Sao Bento in Brazil, Harbour Lights and Wiluna in Australia, Ashanti in Ghana and Tamboraque in Peru. With ongoing development, the efficiency and cost effectiveness of the process have both improved, making it an attractive alternative to conventional refractory treatment processes such as roasting and pressure oxidation. The bacterial culture is robust and can withstand the normal fluctuations experienced on an operating plant. The plants are simple to operate, making it ideal for remote areas. The scale-up potential of the process has been proven, and it can be applied to large refractory ore bodies. The process is environmentally friendly. Neutralization of plant effluents produces precipitates that comply with the most stringent environmental regulations.

Jan 1, 2000

The concept of optical basicity is now being widely applied to rationalize and predict the chemical properties of slags. It employs signals from a probe ion to indicate the "state" or relative "freeness" of the oxygen ions in the slag, and hence provides a fundamental measure of slag basicity. Values of the bulk optical basicity of a slag can either be measured spectroscopically in samples of transparent solid glassy slag, or calculated very simply and accurately from the chemical composition of the slag. The way in which these values vary in different systems are illustrated as isoptical basicity lines on ternary diagrams, and the patterns obtained are discussed. The difficulties associated with assigning optical basicities to the oxides of transition elements are also reviewed briefly. It has been demonstrated that these bulk values can be used as the basis of a flux control model for steelmaking to achieve end-point chemistries much more reliably. Furthermore, several correlations have been established which allow the prediction of the slag-metal distribution of various solute elements. This approach has been used to predict the phosphorus distribution at the end of steelmaking, and also to custom design fluxes for the ladle and tundish to aid in the control of residual elements in the steel such as suphur, hydrogen and nitrogen.

Jan 1, 1990

By Scott G. Britton

Many times during the construction of a project, whether large or small, the engineer will become involved with management of the work and workforce. In some cases, mine management will turn over the direction and responsibility of doing the work to the engineer. Because of this, it is important to know some of the basic principles of human resource applications- among other management concerns. This chapter, therefore, looks at the fundamental principles of human resource management. Three broad discussions are presented to the reader. These are: (1) organization, communications, and responsibilities of management; (2) analysis of worker motivation; and (3) supervisory leadership. Each topic encompasses the current thinking for coal mining and mining management. Much of the information in this chapter comes from Practical Coal Mine Management, by this author and published by John Wiley & Sons, Inc., which discusses in depth many of the ideas presented here. Interested persons are directed to this text for more information on management skills.

Jan 1, 1983

By Liguang Wang, Roe-Hoan Yoon

The thin film balance (TFB) technique was used to measure the equilibrium film thicknesses (H3 between two air bubbles in sodium dodecyl sulfate (SDS) and electrolyte (NaCl) solutions. The results were used to determine the magnitudes of the hydrophobic forces (K232) using the extended DLVO theory. The Km values determined from He measurement allowed us to predict disjoining pressure isotherms, which were found to be in excellent agreement with those obtained experimentally using a bike-wheel film holder. The rate of film thinning was measured at low SDS concentrations with varying amounts of electrolyte (NaCl) added. In general film thinning was controlled by the capillary pressure during the initial stages, while it was controlled by the surfaces forces during the later stages. At low NaCl concentrations, it was possible to predict the rate of film thinning using the Reynolds equation, provided that the driving force was corrected for the contributions from the hydrophobic force, which in turn were determined from the KZ32 values obtained from the He values measured experimentally. At high NaCl concentrations, where it was difficult to measure the equilibrium film thicknesses, the contributions from the hydrophobic forces were determined by fitting the film thinning data to the Reynolds equation. The K232 values obtained using both the equilibrium film thickness and the film thinning measurements showed that hydrophobic force deceased with increasing surfactant and salt concentrations. It was found that the hydrophobic force in foam films was very sensitive to the added electrolyte concentration.

Jan 1, 2005

By G. M. Wilemon, B. J. Scheiner

The Bureau of Mines conducted investigations on extracting phosphate values from fine-particle wastes generated during the mining and beneficiation of phosphate ore by leaching dried wastes using a H2SO4-methanol mixture. Although phosphatic clay waste contains up to a third of the phosphate originally present in the ore, recovery of these values represents a significant challenge due to the fine grain size of the material, the particles averaging less than one micrometer in diameter. Waste samples obtained from two Florida producers yielded phosphate extractions of 71 and 84 pct, respectively, when leached under ambient conditions and at a stoichiometric acid ratio of 1.4:l. Elevated temperatures did not improve the amount of phosphate extracted. Undesirable A12O3, Fe2O3, and PlgO impurities were largely rejected; higher grade wastes gave acids that meet established industry impurity standards and lower grade samples yielded acids that marginally fell short of the standard. Separation of the crude acids from the insoluble residues was accomplished via vacuum filtration through either filter paper or commercial filter cloths. Both filtration rates and solids retention were improved by the addition of 0.5 lb/ton of poly(viny1 acetate) (PVAc) or poly(ethy1ene oxide) (PEO) to the methanol-acid slurries. These results show potential for substantially increasing the reserves of an important domestic resource.

Jan 1, 1989

By Jürgen Lotze

Previously (1981), it was shown that the fiscal policy practised by some IBA-member countries is mainly responsible for a significant shift of known bauxite resources into higher processing-cost categories. The possible impact of politically imposed fiscal costs on the competitiveness of relevant bauxite resources is investigated in detail by means of a model calculation procedure.

Jan 1, 1984

By Kadri Dagdelen, Thys B. Johnson, Salih Ramazan

Long-term production scheduling design is a very important part of mining because it determines the economic outcome of a project There have been many attempts to solve the optimum pit scheduling problem, but there has been no success in developing a scheduling method to give optimum results in maximizing net present value of a mining project. Open pit production scheduling problem can be formulated as a mathematical programming problem and solved using Mixed Integer Programming technique. However, it is not possible to solve the formulation within a reasonable time since the number of integer variables required for the mathematical model is too great to do that by today&apos;s available computer technology. There- fore, a methodology is required to combine, or aggregate, the mining blocks and to decrease the number of integer variables in scheduling without losing the optimality. Therefore, the fundamental tree concept was developed in this paper to combine the blocks. A fundamental tree is defined as any combination of blocks such that: 1. the blocks can be profitably mined, 2. the blocks obey the slope constraints and, 3. there is no subset of the chosen blocks that meets 1 and 2. A Linear Programming (LP) formulation is developed as a mathematical model to find a set of fundamental trees that exist for a deposit. Since the blocks are combined to form the fundamental trees, the number of variables required for the scheduling model is decreased significantly. This decrease in the number of variables makes it possible to mathematically formulate the multi-time period scheduling problem as a Mixed Integer Programming (MIP) model. A case study is performed on a multi-mineral copper deposit in Peru, South America. NPVs of annual after-tax cash flows generated based on the schedule provided by the "Fundamental Tree Algorithm" is compared with NPVs resulted from the schedules coming from three of the computer packages presently available to the mining industry. These are Mintec&apos;s M821V, Earth- work&apos;s NPV Scheduler, and Whittle&apos;s Milava open pit mine schedulers.

Jan 1, 2002

By T. C. Page, P. C. Gibson, M. A. Miller, J. D. Sell

[The Yarnell gold deposit in the Weaver mining district, Yavapai County, Arizona, occurs in a structurally controlled, hydrothermally altered zone in a 1700 Ma granodioritic intrusive. Both potassic and sericitically altered rocks around and above the low-angle, northeast striking Yarnell fault are known to host economic gold mineralization. A wider envelope of weakly-propylitic altered rock also occurs in this area. During mineralization, strong sericitization accompanied several stages of quartz (±adularia) veining, stockwork formation, localized silicification and potassic replacement, in association with deposition of specularite, pyrite (now oxidized) and gold. The footwall of the fault is also sericitically altered but poorly mineralized. Mineralization along the Yarnell fault continues both northeast and southwest from the main deposit, although the thickness of the zone and associated alter avian envelope diminish away from the orebody A sample of undo formed illite taken from the Yarnell fault zone was K/Ar dated at 69 + 1.6 Ma. This date reflects a minimum age for both mineralization and latest movement on the fault. Gold mineralization is accompanied by modest increases in Ag, As. Cu and Mo content. Both CO2- and H2O- rich fluid inclusions were studied and suggest mesothermal pressures and temperatures of formation for the deposit. Ninety-six reverse circulation holes and four diamond drill holes outline a bulk-minable mineral reserve of&apos;4.1 million tons at 0.051 oz of Au per ton. An additional 2.7 million tons at 0.017 oz of Au per ton occurs in a low-grade zone above and subparallel to the main mineralized zone. Total calculated mineral inventory stands at 6.8 million tons at a grade of 0.038 oz of Au per ton, with a waste-to-ore ratio of 1.45:1. Column leach tests indicate that cyanide heap leach gold recoveries should exceed 70%.]

Jan 1, 1994

By S. Gallagher, A. Mayton, R. Merkel

The prolonged exposure of equipment operators to shock and whole-body vibration (WBV) is linked to cumulative back, neck and abdominal disorders. In low coal mines, space restrictions make it difficult for seat suspensions to isolate operators from shock and WBV. Researchers at NIOSH&apos;s Pittsburgh Research Laboratory are responding to these issues by investigating viscoelastic foams. For the full-load case, an ergonomic seat made with viscoelastic foams can isolate the shuttle-car operator from shock at 15 Hz. Researchers used results from additional foam testing using an analytical model to identify viscoelastic foams that provide shock isolation at a frequency below 5 Hz.

Jan 1, 2000

By B. Dabrowski, J. D. Miller, D. Halbe, J. Hupka

An air-sparged hydrocyclone (ASH) mobile system was evaluated for continuous stripping and recovery of cyanide (the AVR process) from process water at a gold plant site. The ASH unit performed exceptionally well as an absorber. HCN was removed from the gas phase in a single one second pass with an efficiency exceeding 99%. HCN concentration in the discharged gas phase was lower than 10 ppm, which provided for a safe working environment. The stripping efficiency, controlled by the Henry’s Law constant, exceeded 40% in one pass.

Jan 1, 2004

By Michael D. Sopko

This paper describes the project implementation from financing, through the engineering and construction phases, mine and process plant commissioning as well as operating experience realized to-date. The single line flowsheet used to process the lateritic nickel ore to a 75 percent nickel matte is presented with emphasis on the main pyrometallurgical operations. These include a rotary dryer, a unique reduction kiln, a 45 000 kVA electric furnace and two Pierce-Smith type converters. Associated infrastructure facilities and services necessary to sustain the 11 300 tonnes (12 500 short tons) per year nickel production rate are also described.

Jan 1, 1979