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By Thomas J. Ferree

The efficiency of Carbon-in-Pulp and Carbon­in-Leach circuits is determined by the degree to which the carbon can extract the gold from the slurry and transport it to the stripping circuit. The 'pick-up' efficiency of the carbon particles is affected by several factors which include the following: * The concentration of the carbon in the slurry. * The surface area of the carbon particles. * The reactivity characteristics of the carbon particles. * The retention time of the carbon in the slurry.

Jan 1, 1992

By Michael N. Allenby

One of the least discussed areas in the ever-improving technologies of gold recovery from ore bodies and tailings is the chemistry of the waters used in the plants. Carbon-in­ pulp, carbon-in-leach, heap/dump leaching and iological oxidation processes are all affected by water quality. The remoteness of a lot of the plants means that the large water requirements can often only be met by a ground water source. The chemistry of waters from different sources poses different problems, but generally a lot of these waters are scale forming. Scale-forming tendencies can be described by calcium, magnesium, barium and strontium assays. They can be notated by Langelier and Ryznar indices. They can be plotted by computer programmes that print out scaling indices at different conditions. The propensity to scale can -be readily determined. The prevention of scaling -or at worst minimisation of scaling -is the ambition of the suppliers of scale inhibition programmes. This prevention/minimisation technology is discussed below.

Jan 1, 1993

By Yoginder P. Chugh

The mining methods used at many opencast brown coal mines in Poland and the German Democratic Republic are not used in the US to any extent. Using bucketwheel excavators, bucket chain excavators, and mobile conveyor bridges, the mining techniques may offer efficient, economic alternatives for operators in the US. These mining methods were observed during visits to several open-cast brown coal mines in Eastern Europe over the past two years. Some of them may be particularly attractive for the large lignite mines being planned in North Dakota and Texas.

Jan 11, 1980

At the dawn of the computer age in the early 1950's, few people in either the minerals industry or the field of electronic data processing (EDP) would have predicted the tremendous impact that the computer has had on the way we conduct our everyday lives and businesses. Herman Hollerith himself (see next page), the Columbia University mining engineer 'turned statistician who developed the first punched card electronic tabulating machines for the US Census Office in the late 1880's, would doubt- less be amazed at the progress that has been made in the application of data processing techniques to nearly all aspects of the mining cycle (Aul, 1974). More than any other factor, the availability of economical computing equipment has led the way for the development of the broad range of mining computer methods described in this text. While limits have been identified for many of the technologies commonly in use today, new technological advancements point to continued exponential advancements in computing price-performance in the 1980's. With those advancements, we may look forward to continued expansion of the role computers will play in mineral production.

Jan 1, 1979

By J. Franko, M. S. Klima

Wet-drum magnetic separators are used extensively for upgrading iron ore and for magnetite recovery in dense-medium separation circuits. In this study, the performance of a continuous, laboratory wet-drum magnetic separator was evaluated both with and without the application of ultrasonic energy when processing dense medium slurries. Test variables included magnetic-to-nonmagnetic ratio, solids concentration and nonmagnetic material. The results indicate that, under certain conditions, the purity of the magnetic material increased after ultrasonic treatment. Key words: Ultrasonics, Wet-drum magnetic separation, Iron ore

Jan 1, 2003

By D. Lelinski, X. Nie, J. D. Miller, J. Hupka, K. Bukka

A preliminary characterization of soil components contaminated at a low level (7 nanocuries per gram) with toxic/radioactive metals has been carried out. Most radioactivity and metals content were present in the minus 100 mesh (<150 µm) size fractions. None of the size fractions examined qualified for uncontrolled disposal at dump sites, thus all material would have to be moved to discharge-controlled landfills. The metal content of the sample was below the limits for economical recovery, therefore eventual processing would be dictated by environmental concerns.

Jan 1, 1992

By William P. Lorenz

The paper describes a uranium by-product recovery plant operating within a copper leach, solvent extraction, and electrowinning circuit. The operation is unique because it is integrated into the main process stream of the copper circuit The plant processes 1408 m3/h of copper solutions containing about 10 mg/L of uranium. An Eluex type process was selected due to its compatibility with the copper leach plant. The paper includes an overview of the copper circuit

Jan 1, 1983

By Jun Han

Coal has been mined in the Kailuan mining area for more than 130 years. The remaining reserves consist of, in large part, coals that would have been considered economically unminable or technically not feasible by the previous generations. Some of the current operations have to resort to overmining because the lower seams had been extracted in the past. This paper deals with the feasibility and proper layout of mining roadways of overmining carried out in the No. 5 seam of Qianjiaying coal mine of Kailuan mining area using numerical and physical simulation. FLAC2D was used to investigate the characteristics of stress and displacement in the overburden after extraction of the lower seams. It also analyzed the proper layouts of gateroads in the upper seams, i.e. locating them in the stress-relief zone of the gob so that their stability can be easily maintained. In addition, a two-dimensional physical model was constructed for investigation of damages to the upper seams due to mining of the lower seams. Finally, based on the results of investigations, proper gateroads layout was designed and successful extraction was implemented for panel 1357 in the No.5 seam.

Jan 1, 2009

By W. J. Pennstrom, J. R. Arnold

Gold Fields installed what was the mining industry&apos;s first commercial gold electrowinning/replate circuit at Ortiz in 1981. Its highly successful operation since that time provided the design basis for a similar circuit at Mesquite, which was started in early 1986. These circuits produce plated gold foil suitable for direct shipment to a refinery or melting directly into bars. Detailed descriptions of the electro- winning and replate circuits are given and advantages and disadvantages are discussed.

Jan 1, 1988

By Rudy Rogers

When Gas hydrate formation rates have two steps: a nucleation induction step and an agglomeration step. Hydrate induction in distilled water is extremely slow because of lack of nucleating particles. Our laboratory found that synthetic anionic surfactants greatly improve both hydrate induction and agglomeration because the surfactant?s hydrophilic head absorbs water molecules and the hydrophobic tail absorbs hydrocarbon gas molecules, creating necessary nucleation sites. Vast hydrate deposits inhabit seafloors. What is the seafloor hydrate nucleating mechanism? We find that nano-particles of smectite clays (bentonite and nontronite) are hydrate-nucleating sites in sea-water-saturated, packed porous media, especially when trace quantities of anionic biosurfactants adsorb on the clay particles. Microbes and their bioproducts proliferate around seafloor gas hydrate accumulations. The seafloor microbe-mineral-hydrate synergy is explored in this paper. Keywords: gas hydrates, biosurfactants, crystal nucleation, smectites

Jan 1, 2008

By B. Beatty

This is a response to M. J. Hrebar&apos;s paper, which tracks in detail the highly productive stripping capabilities of modern large bulldozers at two separate installations. It proves the old adage "economies of scale" and quantifies the advantage of being able to move large loads of dirt over comparatively short haul distances by sliding rather than carrying the load. This discussion examines whether a bulldozer is the most efficient way of using this geotechnical principle.

Jan 1, 1994

By D. Zaharaki

The present experimental study underlines the advantages of factorial design in environmental, geotechnical and waste management experimentation. A typical case study regarding solidification of metallurgical wastes is presented and the main effects and interactions of three main factors are determined in order to establish the optimum experimental conditions in terms of compressive strength. Finally, a regression equation that predicts accurately the real compressive strength of a specimen under various experimental conditions is derived.

Jan 1, 2005

By Rex L. Outzen

Houston International Minerals Borealis Project is an open pit heap leach operation. The operation uses open pit mining, two stage crushing, agglomeration, heap leaching, zinc precipitation and induction refining to produce approximately 50,000 ounces of gold per year. Due to the ore being extremely ameanable to heap leach processing techniques, low manpower requirements and efficient management, the operation is one of the lowest cost gold producing operations in the United States.

Jan 1, 1984

By J. Siege1, R. S. Popielak

A computer model was used to simulate the effect of leakage through confining beds on a hypothetical in situ leach operation in an aquifer with a thin mineralized section. The simulations were used to assess economic and potential environmental implications of leakage on an in situ leach operation. Four scenarios were modeled - three representing cases with different degrees of confinement, and the fourth representing a stratified ore zone under a low degree of confinement. The model simulated the travel path and travel time of lixiviant given the hydraulic conditions prescribed in each scenario. The results show that the travel path and travel times vary by about 10% for confinement ranging from nearly impermeable (essentially no leakage) to an extremely low level (thin confinement with a permeability about equal to that of the aquifer) for isotropic aquifer conditions. The aquifer thickness contacted by the lixiviant varied from 85% to 90%. Horizontally, 55% to 60% of the aquifer was contacted. The flow paths in the stratified aquifer were reduced in the vertical direction and expanded horizontally. Forty- five percent of the aquifer thickness was contacted vertically with 88% contacted horizontally. Break- through time for lixiviant traveling at mid-depth of the aquifer increased two times when the leakage was increased from nearly zero to a value representative of thin and highly permeable confinement. Leakage affects the economics of in situ mining by (1) increasing the time required to leach out the ore, and (2) increasing the thickness of the ore zone aquifer to be restored. The potential for environmental impacts appears to be minor. In all four simulations, the lixiviant did not contact the confining strata. Restoration would be limited to cleanup of the ore zone aquifer within the thickness contacted by lixiviant and within the radius of the lixiviant that traveled farthest away from the production cell.

Jan 1, 1988

By Mathew B. Revell, Martyn L. Bloss

The paste fill system at BHP Cannington&apos;s underground silver-lead-zinc mine is described. The paste fill system has been operational since December 1997 and is the first of its type in Australia. Technical and operational learnings since stope filling commenced are presented. Topics described include plant performance, reticulation system design and construction, pipe wear and failure, rheology, in situ performance and laboratory testing.

Jan 1, 2001

By Raphael Mourad, Colin R. Phillips

Fluorescence, radioluminescence, phosphorescence and thermoluminescence in TLD 100 and 700 are discussed and compared. The energy budget in thermoluminescent material is presented in general terms. Results of measurements of radioluminescence, phosphorescence and thermoluminescence in LiF:Mg irradiated with [a] radiation, using simple facilities, are presented. The calculated energy budget in the exposed chips using [a] radiation is compared to published data using [y] irradiation.

Jan 1, 1981

By James G. Sack, Donald G. Wieland, James H. Meinholz

The paper will describe the $1.7 billion Milwaukee Program. Past contracting practices of the Milwaukee Metropolitan Sewerage District are discussed. To minimize costs and claims, the MMSD has implemented some recommendations from Better Contracting for Underground Construction. Currently implemented are: full disclosure of subsurface data including interpretations, the deletion of disclaimers relating to subsurface information, use of the federal Differing Site Condition clause, payment for mobilization. Also considered was the recommendation concerning Wrap Up Insurance. The MMSD shares and allocates certain designated risks through the Contract. A claims handling methodology has been developed and used on this major construction program.

Jan 1, 1983

By Sean Gallagher, Thomas G. Bobick, Richard L. Unger

This paper describes research by the Bureau of Mines on alternative materials-handling strategies for reducing the costs and incidence of back injuries in low-seam coal mines. Strategies recommended for redesigning materials-handling tasks include elimination of tasks, mechanization of tasks, and matching lifting tasks to the physical capabilities of underground miners. The report also discusses other methods that can be used by management to reduce the costs associated with back injuries. More detail can be found in Bureau of Mines Information Circular 9235 (Gallagher et al. 1990).

Jan 1, 1992

By T. R. C. Aston

Extensive undersea coal reserves, identified in the offshore portion of the Sydney coalfield, Nova Scotia, have resulted in the implementation of a multi-year research program to develop site specific guidelines for the undersea longwall mining operations. At present, uncertainty exists regarding the applicability of the current undersea mining guidelines. Preliminary studies have revealed four potential schemes for monitoring seafloor longwall subsidence profiles: seasurface, subsea, geophysics, and direct monitoring. However, further work has indicated that the use of marine geophysical techniques may be the most effective method of identifying and evaluating seafloor subsidence profiles by comparing pre- and post-mining seafloor topographies.

Jan 1, 1990

By D. Park, V. Gall

The three-dimensional finite element technique combined with a progressive failure approach were used to simulate stress distributions in a complete mine section that occur in response to a longwall mining operation. Due to the availability of a Cray supercomputer, a large-scale, three-dimensional, finite-element model was developed for the analysis. The Hoek-Brown failure criterion, which describes a realistic behavior of rock masses, was used for the simulation of progressive failure. A comparison of calculated and monitored stresses in the mine has shown that the model gives a good representation of stresses in the mine structure.

Jan 1, 1992