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By R. Zaragoza M., M. C. Fuerstenau, C. O. Nebo, J. R. Kelso

The rate of adsorption of gold cyanide on activated charcoal was examined as a function of charcoal concentration and size, temperature, initial gold concentration, pH, and initial concentration of gold on the charcoal. Rate was found to be proportional to temperature, concentration of charcoal and initial gold concentration on charcoal, and to the inverse of charcoal particle size squared. An activation energy of 2.0 kcal/mol was determined

Jan 1, 1988

By A. F. Symonds

The effects of harmonic resonance between the supply impedance and power factor correction capacitors on systems with large harmonic sources, such as mine winders, are well known. The similar effects of resonance with cable capacitance are not commonly encountered and, hence, are not always considered in the design of medium-voltage networks. This article considers some of the aspects of resonance between the supply impedance and the cable capacitance and presents one successful approach to solving the problem.

Jan 1, 1998

By W. L. Cornell, F. W. Benn

The U.S. Bureau of Mines investigated froth flotation techniques to remove heavy metals (Pb, Cu, and Zn) from southeast Missouri lead mill tailings. It has been estimated that southeast Missouri contains between 200 and 300 million st of Pb tailings stored above ground. The tailings were classified as two distinct types: (1) pre- 1968 tailings from the Old Lead Belt (some more than 100 years old) and (2) post-1968 tailings from the New Lead Belt. The objectives of the investigation were to reduce the Pb remaining in the tailings to (500 ppm (<0.05% Pb) and to attempt to recover a marketable concentrate to offset a portion of the remediation costs. The remaining dolomite-limestone would then be used as mining backfill or agricultural limestone. Bench- scale froth flotation removed, in percent, 95 Pb, 84 Cu, and 54 Zn, leaving 94% of the original weight containing, in parts per million, 400 Pb, 40 Cu, and 300 Zn from the Old Lead Belt tailings. Separate flotation tests also removed, in percent, 85 Pb, 84 Cu, and 80 Zn, leaving 75% of the original weight containing, in parts per million, 400 Pb, 200 Cu, and 500 Zn from the New Lead Belt tailings . Concentrates recovered from the Old Lead Belt were retreated to produce a final Pb concentrate containing 72% Pb with a cleaner flotation recovery of 79%. Froth flotation proved to be a viable method to remove the heavy metals.

Jan 1, 1992

By R. R. Fernández

Newmont Mining Corporation has been processing refractory gold ores by roasting since January 1995. The ores are refractory due to the association of the gold with iron sulfides, namely pyrite and marcasite, and the presence of carbonaceous components and is oxidized in an oxygen-enriched gaseous atmosphere. The structural characteristics of the calcine have a strong influence on the eventual recovery of gold by cyanidation. These characteristics are strongly dependent upon the roasting conditions, mainly the roasting temperature. Originally, the sulfides and carbonaceous matter were oxidized at a temperature that typically ranged between 535 and 560 °C. Controlling the roasting temperature within the lower and narrower range of 510 to 515 °C produced a calcine with a larger surface area(e.g. higher porosity), which resulted in a gold recovery increase of3.3 percent in 2001 equivalent to 5.1 million dollars of additional gross revenue. The new strategies of operating at temperatures never tested before are discussed. It constituted a great challenge to the control room operators for the lower operating temperature falls much closer to the ignition temperature of the sulfide ore and smaller and more frequent adjustments in operating parameters were needed to improve and maintain high gold recoveries. Based on the encouraging results that were achieved in 2001, a decision was made to install a “smart” process control system because the roaster temperature control was performed by manual inputs from the control room operators. The development and implementation of the control system to reduce or eliminate the temperature variability between the different control room operators commenced in June of 2002 and was fully operational by the end of October. Lower roaster temperatures were achieved (500 to 505 °C), which resulted in further increase of gold recovery by about two percent. The overall recovery increase equated to 8.0 million dollars of additional revenue for the first 10 months of 2002.

Jan 1, 2003

By Derek M. Hutchinson, Don Zeni

The construction of shafts by blind drilling has been made cost effective by advances in technology and experience. The techniques of blind shaft drilling are discussed and a brief history presented. A recent use of blind shaft drilling to access a small gold ore body in Australia is described. Finally, the most recent developments in drilling machinery are reviewed together with possible applications in new and existing mines.

Jan 1, 1987

By C. R. Euston, B. T. Field, W. E. Lindquist

Pyroprocessing applications in the minerals industry range from low-temperature drying to high-temperature reactions. Material characteristics and process requirements range over a very broad spectrum and can confuse plant engineers trying to select a pyroprocessirtg system for their plant. This paper examines the important process variables and offers empirical guidelines to assist in a user&apos;s overall process evaluation.

Jan 1, 2000

By Stanley J. LeFond

After two disappointing years where most industrial minerals posted decreasing production, 1981 saw an increase in production over 1980, or at least in status quo. Several commodities did, however, post significant gains. For example, bromine posted a 14% increase; fluorspar production dropped 21% in 1980, but gained 24% in 1981; and sulfur production increased. However, perlite was off 13% and manufactured sodium sulfate off 18% in 1981, while natural sodium sulfate production remained almost even with 1980. In fact, many industrial minerals production either remained constant, increased, or decreased only slightly over 1980. Increasing energy costs had their impact on industrial minerals in 1981. Hopefully, the recent downward trend in energy costs, at least gasoline, will financially help some of the more marginal plants. The 1979 shortage of rail cars that did not carry through 1980 also did not carry through in 1981. Rail rates increased 12.8% over-all last year, while average freight rates for industrial minerals increased 15.5%, according to Neil Johnson, consultant. Also, the trucking industry posted a 5-6% decrease in rates due to deregulation. All in all, we in the industrial minerals section seem to be holding our own at least. Stanley J. Lefond Contributing Editor

Jan 5, 1982

By Conrad Parrish

As originally conceived, this paper was to address the costs of environmental compliance, focus on environmental impact statements, and describe how those costs impact mining projects. The intent was to do wide ranging mathematical analyses to demonstrate the varying impacts on mining projects depending on their size, timing, return on investment and other salient project features. The initial portion of the numerical analysis necessary to this purpose was performed. The results showed a pattern of impacts familiar to the mining industry:

Jan 1, 1991

By Bruno Paponetti, Luigi Toro, Carlo Abbruzzese, Maria Y. Duarte, Anna Marabini

A bioleaching process has been developed to extract manganese from low grade domestic resources not amenable to conventional mineral processing operations. Between the different strains of microrganisms tested, Thiobacillus ferrooxidans has appeared poor over manganese, Aspergillus niger allowed to obtain high recovery, probably due to the metabolic production of citric and oxalic acids, showing a remarkable complexing and reducing action. The growth of microflora has been correlated to the MnO dissolution as confirmed by SEM observation.

Jan 1, 1989

By J. D. Raulerson, R. P. Farias, G. A. Gruber

A flotation process has been developed to successfully treat ore from the Santo Domingo phosphate deposit in Baja California Sur. The ore contained less than 4% P2O5 with quartz, silicates, and carbonates as gangue minerals. Flotation of the low- grade feed in seawater required that the conventional Crago process, comprising direct anionic flotation, deoiling, and inverse cationic flotation, be augmented by an anionic cleaner flotation step, phosphate depression, and a calcite flotation step.

Jan 1, 1988

By Lynn I. Kelley

Industrial-mineral production contributes on the order of CDN$1.5 billion per year to the economy of Saskatchewan, Canada. Potash is the primary industrial mineral produced in the province, followed by aggregate, sodium sulphate, salt, potassium sulphate, peat, clays, silica sand, calcium-chloride brine, and "clinker." Potentially economic deposits of kaolin, diamond, and building stone are under evaluation. All of the major deposits of commodities discussed here are located south of lat 56°30&apos;N. Most of the locations are presented on Figure 1 POTASH Saskatchewan supplies approximately 30% of the world&apos;s demand for potash. Eight conventional underground mines and two solution mines produced an all-time high of more than 13 million metric tonnes of potash (KC1) (8 million tonnes K2O equivalent) in 1997, valued at over CDN$1.4 billion. All of the mines exploit the middle Devonian Prairie Evaporite. The four potash-bearing members of the Prairie Evaporite underlie much of southern Saskatchewan and extend southward into North Dakota and Montana and east- ward into Manitoba (Fig. 2). Halite and anhydrite separate the potassic members. The evaporite beds locally are interrupted by solution structures (anomalous ground). Some of the structures may be related to deep-seated tectonic features.

Jan 1, 1999

By Arthur B. Steiker

Digital simulation was used to model a proposed underground&apos; train system. The trains are to haul ore from numerous loading points beneath the production area of the mine to a central underground dump location, and then return to the mine. The purpose of the simulation was to aid mine engineers in studying various alternatives and configurations regarding track layout, crusher (dump point) specifications, dispatch procedures, fleet size, and train length, among others. The simulation&apos; model can also be used to study the same aspects of existing haulage systems. To accommodate a wide and initially unknown range of system designs, a modular model structure was developed with major components devoted to track routing, train movement, loading process, dumping process, and dispatch. Key statistics tabulated were number of trains dumped during a simulated week, queueing delays in the mine and at the crusher, crusher utilization, cycle time, and percent of time for each: activity (loading, moving, dumping, etc.). The simulation results were instrumental in identifying a train system design which would reduce queueing delays and meet production goals with a minimum of trains and track mileage.

Jan 1, 1982

By S. R. S. Sastri

By using the data of E.A. Hersam and F.C. Bond&apos;s equation for energy consumption in comminution, a method was developed to analyze the performance of industrial jaw crushers. The study showed that industrial jaw crushers are generally operated below capacity. The study also showed that industrial jaw crushers generally have sufficient installed power to operate at, full capacity. The method presented can be used to estimate the capacities and power requirements of jaw crushers.

Jan 1, 1995

By I. C. Watson, J. W. Klokow, A. F. Knoetze, R. G. B. Pickering

In the late 1970s and early 1980s there were a number of attempts to use Tunnel Boring Machines in deep level gold mines. These attempts must be regarded as unsuccessful. Since then there have been comprehensive developments in tunnel boring equipment and tunnel support technology. This paper defines the problems experienced in those early trials, reviews the technology development, and concludes that tunnel boring in deep level goldmines can be justified in today’s environment.

Jan 1, 1999

By Dan J. Van Roosendaal

A closely spaced grid of survey points was installed over the tensile zone of a longwall panel in southern Illinois and monitored daily during subsidence to document the complex ground-surface movements associated with dynamic subsidence. Vertical and horizontal displacements were used to calculate maximum tilts and principal strains within the grid. The dynamic nature of subsidence is made evident by changes in both the direction and magnitude of maximum tilts and principal strains. The maximum tilt (smax) of 0.036 and maximum tensile strain (Emax) of 0.027 were measured after subsidence and were oriented transverse to the longwall panel. Observations of surface fracturing were correlated with strain determinations to estimate a surface strain at incipient cracking (E;) of 0.006 to 0.009. Using shallow inclinometers, a linear variation of horizontal displacement with respect to depth was observed, suggesting a neutral¬axis bending mechanism for near-surface deformation. Horizontal displacements transverse to the longwall panel reduce to zero at a depth of 40 feet. A linear relationship between strain and curvature was used to estimate ground-surface curvatures associated with Emax (0.00068 ft-1) and E; (0.00015 to 0.00023 ft-1). The curvature estimates are consistent with published results.

Jan 1, 1986

By D. B. Jenkins, D. R. Taylor

Treatment of bentonite clay with mineral acids yields a modified clay product of high surface area and acidity that exhibits enhanced adsorptive and catalytic properties. A highly specialized segment of the clay industry based on this process has evolved into a worldwide business with a capacity of about 500 kt/a. This paper will present data on the chemistry, mining, manufacturing, and applications for acid-activated clays.

Jan 1, 1988

By Rudrajit Mitra, Wesley B. Johnson, Erik C. Westman

The ability to understand stress redistribution within a mine allows greater extraction efficiency with reduced safety concerns. Stress redistribution has been examined at the laboratory scale using ultrasonic tomography and numerical modeling using PFC3D. A data acquisition system was built to obtain tomograms as samples are loaded in uniaxial compression. Limestone samples were loaded to failure. Three-dimensional tomograms of the samples correlate to various stress distributions. The tomograms are compared to analytical and PFC3D results.

Jan 1, 2005

By S. Behl

In the selective flocculation process, polymers with specific functional groups can yield highly selective adsorption and, therefore, high separation efficiency. Selectivity in polymer adsorption may also be attained by specific additives that inhibit the adsorption of the flocculant on some solid surfaces but not on others. Generally, these additives have a different chemical nature than the flocculant. In this study, the lower molecular weight fraction of the flocculant was successfully evaluated as a site blocking agent, leading to higher separation efficiency than obtained otherwise.

Jan 1, 1993

By Yoginder P. Chugh

It is well known that weak floor conditions in central Illinois affect pillar and mine opening stability. The floor interaction with coal pillars and immediate mine roof are being studied using two dimensional (plane-strain) elastic-plastic finite element models. The effects of varying soft floor thickness, coal seam- thickness, width of mine openings and strength parameters of coal and mine floor are being evaluated. The finite element models developed by Agbabian Associates and Dahl were utilized in this study.

Jan 1, 1982

By Donald W. Gentry

This article introduces mine planning as a complex process based on the quantitative and qualitative assessment of a myriad of independent and inter-or co- dependent variables. The interdependent variables of particular interest in this paper are those associated with mine planning activities that impact metallurgical processing plant performance and costs. These variables are identified and examples are provided to substantiate the argument that the magnitude and sensitivity of these variables must be formally assessed and analyzed to determine their potential impact on overall economics.

Jan 1, 1991