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By Christopher Haycocks

Subsidence induced innerburden shearing and stress fields, whether active or passive, frequently contribute to significant ground control failures in overlying seams. In this paper proven multi-seam technology is used on upper seams to forecast and quantify the magnitude and severity of damage and the increased mining risk due to interaction. Increased upper seam ground control problems are demonstrated using hazard mapping which provides a viable technique for utilizing damage predictions in design.

Jan 1, 1986

By R. Pazhianur

Many investigators conducted surface force measurements between hydrophobic surfaces in water, and observed attractive force that was substantially stronger than the van der Waals attractive force. The excess force was appropriately referred to as “hydrophobic force”, for which many different theories have been put forth by numerous investigators. In an earlier publication (Yoon and Ravishankar, 1996), it was suggested that the hydrophobic force maybe due to the interaction between the large dipoles created by the surfactants adsorbing on solid surfaces in patches (or domains). In the present work, a mathematical model has been developed to further elaborate the theory.

Jan 1, 2003

By D. C. Shumway

Mining in Cushenbury Canyon began in 1860 when John Cushenbury left his Holcomb Valley gold prospect and discovered a silver vein in the limestones of the present day Cushenbury Mine. Cushenbury Canyon is located along the western boundary of the Mojave Desert in Southern California and on the north slope of the San Bernardino Mountains. The Holcomb Valley, immediately southeast of Cushenbury Canyon was the most prolific gold producer in Southern California. Gold mining dominated the area until World War II when interest in the Lucerne Valley Limestone deposits was peaked by the construction of the Kaiser Steel Plant in Fontana, California. The steel making process required large amounts of metallurgical grade limestone and Kaiser geologists located claims in most of the limestone deposits. Kaiser Cement constructed a cement plant and limestone mine in Cushenbury Canyon in 1956. Kaiser Cement modernized the facility in 1982 to a four stage preheater-precalciner system. Mitsubishi Cement Corp. purchased the property in April, 1988, and through further system modifications have created the most efficient and modern cement plant in the United States.

Jan 1, 1992

By Greg T. Saretzky, Wilson G. Ward

A comprehensive hydrologic study was completed far the waste rock dump at Equity Silver Mine, BC. Characterization of the hydrologic system included geologic structure. topography, surface hydrology and groundwater systems. The results of the study conclude that the cover system is restricting net infiltration to approximately 5%. However, significant discharge continues to occur from the perimeter of the dump. A three dimensional seepage analysis was carried out to illustrate the influence of groundwater discharge associated with the regional topography and geologic structures. The results of the modelling program show that groundwater discharge occurs from the waste rock dumps when high recharge rates are specified for the surrounding topography- This groundwater discharge strongly influenced by the high hydraulic conductivity assumed far the fractured bedrock. The modelling results are considered preliminary and field drilling and piezometer installation is being conducted to determine the groundwater regime in the vicinity of the waste rock dump.

Jan 1, 2000

By T. Chandler, R. Buchan, J. H. Blowes, E. G. Haldeman

The regional geological setting and nature of the serpentinized ultramafic rocks are described. It is postulated that lateritization started in Miocene time. Repeated uplifts led to at least four physiographic cycles and to the development of a mature lateritic soil profile. Complete profiles are subdivided from top to bottom as follows: Zone A - chocolate-brown limonite; Zone B - ochre-brown limonite; Zone C - soft serpentine; Zone D - hard serpentine; Zone E - serpentinized peridotite; Zone F - ultramafic rock. Zones A and F rarely attain ore grade. Canga is conspicuously absent. Rocky ore of Zones D and E amounts to 40%, limonite ore of Zone B to 25% of total ore reserves. Nickeliferous serpentine is the major crystalline phase in Zone C. In this zone and deeper, crystalline quartz occurs, particularly in fracture zones where nickeliferous cryptocrystalline quartz is of ten accompanied by garnierite.

Jan 1, 1979

By N. Teasdale

The Bousquet #2 deposit, located within the Blake River Group in the Abitibi Greenstone belt, midway between the towns of Val d'Or and Rouyn-Noranda, exhibits all of the distinguishing characteristics of volcanogenic massive sulfide (VMS) deposits. As such, the deposit can be compared with other gold-rich VMS deposits such as the world-class Home deposit in Rouyn-Noranda, Quebec, Canada and the Mount Morgan deposit near Rockhampton, Queensland, Australia.

Jan 1, 1995

By Clinton Strachan, Rob Dorey

10.1 INTRODUCTION This chapter presents considerations which should be applied to heap leach pad site selection, site evaluation, and design, relative to the geotechnics of the site and ore. 10.1.1 General Guidelines are presented covering the topics encountered in design and construction of heap leach faci1ities. Because geotechnical characteristics vary from site to site, not all geotechnical topics associated with a specific heap leach facility are presented, and there may be exceptions to some of these guidelines. The general features of a heap leach facility (from Chapter 1) to be discussed in this chapter are: • Leach pad (including leach pad foundation and liner); • Heap; • Solution storage faci1ities (for pregnant and barren process solutions) ; and • Solution collection facilities (which collect and convey solutions in the heap and convey them to solution storage facilities). These general features are illustrated in Figure 10.1. Liners for these facilities are discussed in Chapter 11. Solution application systems and the sizing aspects of solution storage facilities are discussed in Chapters 6, 7, and 12. The general features listed above are constructed with and overlie naturally occurring materials (such as ore, borrow soils, and subsurface soils and rock). These natural materials are relied upon to perform in an acceptable manner as a component of the leach facility (such as the liner, drain material, and foundation).

Jan 1, 1988

By R. M. Imhof, M. J. G. Battersby, J. V. Brown

There is a plethora of former industrial sites where coal mining operations have left large slurry impoundments. These contain raw washed fines, which have previously been too expensive to process to requisite grades for commercial use. New technology has been developed for fine material processing, namely the Imhoflot pneumatic flotation G-Cell. This froth flotation technique is a highly efficient means of concentrating coal and is particularly appropriate to the nature of materials encountered in tailings ponds. The high volumetric throughput resulting from the vastly reduced residence time in the cell allows for drastically reduced equipment sizes when compared to conventional flotation cells. This means the process, when combined with innovative pre treatment and filtration equipment can be developed as a mobile plant concept. This is seen as a minimum requirement when re-treating and rehabilitating fine coal ponds.

Jan 1, 2003

By Murali M. Gadde

Perimeter mining is a special form of very productive partial extraction method practiced at some mines in the United States. In the Illinois Basin mines where all major coal seams have weak underclay in the immediate floor, experience shows that any long-term ground control issues will arise due to floor failures rather than instability of the coal pillar itself. While there is a significant amount of work done on floor stability associated with regular pillars, no work has been done so far on the stability of perimeter pillars. This paper reports the results of a comprehensive study that was conducted for the first time on floor stability during perimeter mining in the Illinois Basin mines. A special plate template, which mimicked a common perimeter pillar configuration was created to conduct in-situ bearing capacity tests at five mines in three states of the Basin. Additionally, because of the complex shape of pillars created in perimeter mining that defies any closed-form solution, floor bearing capacity was studied using three-dimensional nonlinear numerical modeling. Based on these in-situ and numerical studies, some guidelines are provided for perimeter pillar stability analysis.

Jan 1, 2009

By J. C. Armbrust

The Morenci Open Pit Mine, located in south-eastern Arizona, is owned and operated by Phelps Dodge Morenci, Inc. The Mine has been predominantly a rail mine since its origin in 1937. However, beginning in early 1986, a program was initiated to phase out the rail mining operation and replace it with a more flexible and productive truck haulage scheme. This transformation from rail to truck haulage will be accomplished when the current in-pit crushing and conveying project is completed in late 1988.

Jan 1, 1988

By G. Whitney, J. Steiner

Introduction The Summitville Mine located in southwestern Colorado is an example of the potential impact that natural weathering and mining activities can have on environmental quality. Acid rock drainage and metals leaching from active and historic mine districts are a major environmental problem facing the mining industry today. Sulfide ore exposed naturally or during mining operations has the potential to produce leachates that contain high concentrations of dissolved metals. These leachates can affect the quality of plant and animal health in surface water used for agriculture, recreation and human consumption. Pintail Systems has developed biological processes for detoxification of cyanide in heap-leached spent ore and process solutions. During application of spent ore cyanide bio-detox processes we have also observed a substantial reduction in many of the leachable metals in biotreatment solutions. These field observations of soluble metal reduction led us to propose that metal bio-mineralization should be a secondary treatment goal of spent ore detox in Focused Feasibility Studies (FFS) for the Summitville Mine. In the FFS (described in a companion paper) for Summitville, spent ore from the heap leach pile (HLP) was loaded into PVC test columns (six inch X ten foot) and was leached with bacteria/nutrient solutions. Two treatment designs were studied: a standard percolation leach (aerobic) and a saturated leach design where the ore was saturated with the heap leach solution to which bacteria and nutrients were applied in a continuous biotreat leach. The bacteria for all column treatment tests were isolated from the spent ore at depth through the Heap Leach Pile (HLP) in the saturated and unsaturated zones. Bacteria isolated from the heap material were tested for cyanide oxidation capacity and were submitted to a bioaugmentation program to improve reaction kinetics and metals tolerance. The final treatment population consisted of several distinct species including aerobic heterotrophs, facultative anaerobes and sulfate-reducing bacteria. The remineralization of soluble metals was observed through a decrease in copper in column leachate solutions and the formation of observable mineral products on ore surfaces in the columns. Several of the tests were run in clear PVC columns to facilitate observation of mineral formation. The column ore contents were photographed before, during and after the biotreatment process which ranged from 10 to 20 days for each test column. Ores were collected from each column after the treatment was complete and were submitted for SEM and TEM study at two laboratories - the USGS SEM Laboratory in Denver, Colorado and the City College of New York SEM laboratory. Treatment Process Description Numerous species of bacteria, fungi and yeasts are capable of accumulating many times their weight in soluble metals. Both living and dead biomass are effective in removing soluble metals from waste streams containing gold, silver, chromium, cadmium, copper, lead, zinc, cobalt and others. Soluble metals may also be immobilized in soils by natural or engineered biomineralization reactions. Several commercial processes using biological reactions are being applied on an industrial scale for metal remediation. Bacteria found in natural and extreme environments have developed a wide variety of metabolic functions to adapt to these environments. These natural microbial functions contribute to global mineral cycling that continuously forms, transforms and degrades minerals and metals in the environment. Biomineralization is described as a surface process associated with microorganism cell walls where the remineralization occurs. The biogeochemical activities initiated by microorganisms in ores, soils, surface and groundwater environments can dominate the formation and transformation of those mineral environments.

Jan 1, 1995

By QU Hong-lue, YANG Lin-han

Aiming at the subjective impact caused by subjective weighting method in the establishment of rockburst risk attribute identification and prediction model, the combined weighting method was introduced to eliminate the influence of unreasonable weight of each index. Eight discriminant indexes affecting the risk of rockburst were selected. Through the literature review, relevant rockburst cases were collected and 8 index rockburst sample sets were established. A variety of machine learning methods were used to analyze the feature importance of discriminant indexes in the samples, and then to determine the objective weight values of different methods. Combined with the subjective weights determined by the Analytic Hierarchy Process, the combination of weights were successively carried out. Based on the attribute recognition theory, the combination weights with different objective weight methods were established to identify the rockburst risk attributes, and verified by the confidence criterion. The results show that the objective weight value determined by the feature importance analysis of machine learning reduces the subjectivity of the weight of Analytic Hierarchy Process method, improves the prediction accuracy, and makes the prediction result closer to the fact.

Apr 26, 2022

The most common method used for cleaning the fine fraction in today's coal preparation plants is froth flotation. Past research and practice has found that froth flotation achieves excellent separation efficiencies for fine coals having only a small fraction of middling particles. However, its efficiency decreases sharply as the concentration of middling particles increases due to the flotation of high-ash particles having a small amount of hydrophobic coal present at the coal surface. Since gravity-based processes are much more efficient at treating middlings, the application of centrifugal washing for fine coal cleaning has been studied with an emphasis on the primary cleaning of fine circuit feed. Results will be shown from a parametric study using a Falcon centrifugal concentrator which reveals that the separation performance is a function of particle size, bowl geometry, feed solids content, and feed rate.

Jan 1, 1994

By M. B. Díaz Aguado

Traditionally, the practical evaluation of a mining project for a potential investment has been made considering mainly technical aspects. But the concept of sustainable development has introduced significant changes in the factors analyzed to make the final decision. This paper proposes an empirical evaluation of a project considering not only technical, economic and financial parameters, but also associated risks and other intangible aspects, such as political considerations, stability in the legal frame, social factors and environmental issues. The proposed methodology is practical and easy to apply for project management. Among its main advantages, the following could be quoted: using this evaluation two different projects or locations of a same project can be compared, future behaviors could be predicted, the index incorporates a new approach to specific mining projects and this perspective could also be applied to other projects with environmental and social impact, such as civil works or industrial projects.

Jan 1, 2007

Iron ores may be upgraded by flotation of iron oxides or siliceous gangue using either cationic or anionic collectors. The electrostatic mechanism of adsorption can account for the complex chemistry involved. In industrial practice, only cationic silica flotation is used at present in North America. Some of the seemingly paradoxical phenomena of cationic silica flotation behaviors in meeting the demand for low silica concentrates are reviewed.

Jan 1, 1989

By J. A. Brierley, C. L. Brierley, K. A. Prisbrey, R. W. Bartlett, J. G. Harrington

Bacterial oxidation of gold-encapsulating sulfide minerals in low-grade refractory ores was investigated over a period of one year. Crushed ore samples were held in wet, bacteria-inoculated, aerated columns. Sulfide mineral oxidation data were correlated with subsequent gold cyanide extractabilities. Experimental results for both sulfide conversion and gold extraction were compared with a biooxidation kinetics model that incorporates rock size, mineral grain size, and heterogeneous pyrite reaction kinetics. Using the model, extrapolations were made over three years for biooxidation of ore in large stockpiles. Ferric ion (oxidant) diffusion in the solution-filled pores of the rock matrix does not control the biooxidation kinetics of ore crushed to -25 mm.

Jan 1, 1993

By Al. Valero

This paper quantifies in universal units (energy units), the annual decrease in the mineral endowment of the planet. This is done for some important extracted non-fuel minerals, namely aluminium, cobalt, chromium, copper, gold, lead, uranium and zinc and is compared with the depletion figures of conventional fossil fuels. The results of this study reveal that each year, the decrease of the global non-fuel mineral bonus provided by Nature is 2 to 3 orders of magnitude greater than the loss associated to the burning of fossil fuels. Particularly for 2008, the depletion in mineral wealth of the studied commodities was about 20 times greater than that of fossil fuels. The assessment methodology is based on the Second Law of Thermodynamics. It quantifies the useful energy (exergy) required to concentrate a mineral from a completely dispersed state in the crust, to the conditions of composition and concentration found in the mines. Exergy can be a useful measure for quantifying the mineral depletion caused by man, as it takes into account the main physical features that make minerals valuable: composition and concentration. This analysis enhances and puts numbers to the importance and necessity of material reuse and recycling.

Jan 1, 2011

By A. J. P. Durham

Two low water flux test covers were placed on acid generating waste rack dumps at the Kidston Gold Mine in Queensland, Australia The climate is semi arid with distinct wet/dry seasons. The present study was initiated to develop a cover system to restrict infiltration. The design of the cover required optimization of water storage and evapotranspiration. Instrumentation was installed on both dumps to measure infiltration, moisture conditions and climatic parameters. Field measurements over the last three years indicate that both covers are performing satisfactorily. Selection of the final cover for closure is described on the basis of these results.

Jan 1, 2000

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 J. Fuller, L. Marsden

Windborne dust from alkaline salt flats and mining-related tailings ponds is especially prone to threaten applicable ambient air quality standards. Sodium carbonate crystals, typically present, weather to an exceedingly fine, non-cohesive dust, causing air quality problems for miles downwind. Recently developed specialized polymers react with alkaline dust to form sturdy, wind-resistant crusts with good longevity. An on-going demonstration project at a major trona facility has developed techniques for cost-effective application of these polymers over large areas of soft tailings or sediments in a wide variety of situations. Recently treated areas on the order of 80 acres show effective suppression of dust.

Jan 1, 2004