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By J. C. Fox, V. L. Ketellapper

The Summitville Mine, located in the mountains of Southwest Colorado, is an abandoned gold mine. From 1984 to 1992, Summitville was mined for gold using an open pit heap leaching technology. During this period, the volume of acid mine drainage released from the mine significantly increased. This was attributed to the development of the mine pits, the waste rock piles, the heap leach pad, and increased discharges from the drainage adit. The release of this acid mine drainage resulted in the destruction of the aquatic ecosystem for more than twenty miles downstream of the mine. Beginning in 1993, plans were implemented to reduce the amount of acid mine drainage released from the mine. The majority of this work has been completed at the mine. This work includes removal of the Cropsy Waste Pile, closure of the Heap Leach Pad, and revegetation of disturbed areas. Significant improvements to water quality downstream of the mine have occurred resulting from mine reclamation. Aquatic life has returned to portions of the previously mining impacted areas. This study discusses the actions taken to reduce the amount of acid mine drainage generated at the Summitville Mine, the costs of these actions and the resulting reduction in metal loadings. Over 250 samples taken at over 10 locations since 1993 form the basis of this evaluation. Copper loading is analyzed as an indicator of the effectiveness of the actions taken.

Jan 1, 2002

By W. Chae

The influence of solution ionic strength (IS) and electrolyte valence on the flotation behavior of malachite has been investigated. The microflotation tests were conducted over a range of solution IS (1?300 mM) at a constant speed (340 rpm), pH (9.5), flotation time (10 min), and sodium oleate dosage (5.3×10-7 moles/g). The size of malachite ranged from 45 to 53 µm, and two different types of electrolytes (NaCl and CaCl2) were employed. Electrophoretic mobility was also measured over the same IS range employed in the microflotation study. Overall, strong coupled effect of solution IS and ion valence was observed. Specifically, the flotability of malachite increased with increasing IS in the presence of monovalent cation (Na+) while the flotability increased up to 30 mM and decreased with increasing IS in the presence of divalent cation (Ca2+). Notably, the flotability of malachite was greater with the presence of Na+ compared with Ca2+ under high IS conditions (IS>30 mM). Consistent trend for Na+ versus Ca2+ was observed from the flotation results with different SO dosages. The characterization and flotation results suggested that the trend was likely attributed to the increased unfavorable interaction between malachite and bubble via the charge reversal of bubbles and malachite at higher IS in the presence of Ca2+.

Feb 27, 2013

By J. Parker

Gentlemen; Rainy day in Upper Michigan, a good time to catch up on reading. Am doing that, and have a couple of questions concerning the K and P paper on roof problems and supports. I wonder if the authors can enlighten me. The compressive strength of the coal was reported as 4.4 MPa (633 psi) and compressive stresses measured in the coal seam were reported at around 27.6 and 48.2 MPa (4000 and 7000 psi ). Can such a soft coal actually contain such a high level of stress? Can it be measured as if the material were elastic, or does the coal behave plastically? Can that stress level be confirmed with hydraulic load cells? And if the coal is so soft, and if it is plastic, why is the stress field not hydrostatic? The intact roofrock appears to be unusually strong, with compressive strength reported at around 145 MPa (21,000 psi), and some failures were noted as soon as the rock was exposed. Were tests run to find out how that rock responded to the addition

Jan 1, 1991

By S. A. Shuey, P. Taylor

The recycling of electronic waste (e-waste) tends to be a rather complex undertaking when considering the intimate bonding of materials in the average printed circuit board. The development of a recycling process is further complicated when considering the wide variety of products being generated under the heading of “electronics” as well as the constant change in materials of construction coupled with the speed at which electronics are changing. CSM researchers have undertaken a survey of the current state of pyrometallurgical processing of e-waste. This base-line will set the stage for the development of new recycling technology at CSM.

Jan 1, 2004

By Harold J. Schock

The cases of no auxiliary ventilation and ventilation with tubing were mathematically modeled, using a turbulent dispersion model. The scooptram that is used to load is modeled as a variable-speed, variable-strength source of pollutants moving in and out of the dead-ended drift. Model predictions are compared to experimental measurements. A parametric analysis was performed to determine the effect of exhaust pipe location and time spent out of the drift, as well as to determine if a relationship existed between CO2 and NO levels. It was concluded from this analysis that when modeling a load-haul-dump cycle, it is necessary to use a model that has the capability of predicting changes in source strength as well as source location. It was also determined that four relevant factors include effective heading height, apparent longitudinal diffusion coefficient, transverse concentration gradient at the face, and average dispersion width of the exhaust jet. As these factors change with heading geometry and ventilation configuration, they were determined experimentally, Carbon dioxide was used as a tracer to calibrate the model; since, knowing the fuel flow rate, it is possible to calculate CO2 production. The above four factors in the computer model were calculated using a regression analysis, comparing predicted local concentrations to measured local concentrations. The model was then verified after this calibration process using additional experimental results. With the calibrated model, it is possible to predict pollutant concentrations at any location in the heading using an engine map and the previously calculated flow field. A parametric analysis shows that the exhaust pipe location can have a significant impact on operator exposure to exhaust gases. It was also shown that NO concentration varies directly with C02 levels. Predictions using the dynamic model are contrasted with constant source strength (pollutant flow rate) results. An analysis of these predictions for computing time-weighted average NO shows the dynamic model predictions of operator exposure to this pollutant to be less than one-half of the value predicted using a constant source model.

Jan 1, 1981

By P. Sarnoff

Gold has always been a crisis investment. For centuries gold has been considered globally the money of last resort. In time of war, inflation, financial uncertainty, political upheaval there has with few exceptions always been a flight to gold. The gold paradox simply is that even though we have gone through for the past handful of years all the kinds of. anxieties that would cause the gold price to rise, it has instead dropped drastically. Figure 1. illustrates the important factors that influenced the gold price significantly up or down before 1987. Obviously, since then, even though we have had wars, inflation, financial problems involving breaking banks and thrifts let alone collapsing financial institutions, the gold price has both in the long-term and the short-term trended downwards. Figure 2. depicts the gold price path since 1987. If the presence of time-honored and time-tested factors that should have driven the gold price up didn't do the job, then logic dictates that new factors to drive the gold price down and keep it depressed arose. And they did. But before addressing these depressants permit me to turn to the arcane art of gold price prediction and fore-casting.

Jan 1, 1992

The OptiPit® software program is developed based on expertise gained at the Colorado School of Mines (CSM) using Mixed Integer Linear Programming (MILP) techniques. This program has been developed to satisfy the need in the mining industry for a multi-time period schedule and cutoff grade optimization tool that handles large scale open pit and underground mining operations involving many dumps, stockpiles, complex processing options and blending requirements. The current software (or earlier development versions) has been beta tested and used on various large scale projects within Placer Dome Inc., Newmont Mining Corporation, and Phelps Dodge Corporation since 2003. Through the use of this software, these companies experienced additional value creation by optimizing mine sequences, cutoff grades, material process flows and stockpiles under complex operational and processing constraints. This paper will present simple case study results to demonstrate the power of OptiPit® when used as a cutoff grade optimization tool. Furthermore, the paper will show, by example, how significant the difference in the Net Present Value (NPV) of a given project can be, depending on whether results are obtained by way of cutoff grade optimization using OptiPit®, or by using traditional breakeven cutoff grade approach.

Jan 1, 2007

By L. E. Beverage, K. L. Johnston

This paper will address methods for minimizing liability and protecting materials from disclosure as result of self- evaluative audits and internal investigations. Specifically, the paper will cover the role of counsel in the investigative process and how best to design and conduct internal investigations to minimize the development of problematic material and disclosure of information. The paper will also address the extent of privileges that may be relied upon to protect materials and information from disclosure. These include the attorney-client privilege, the self-critical analysis privilege, and the attorney work product privilege. These privileges are qualified and understanding the limits of their coverage is essential to minimizing liability.

Jan 1, 2001

By Paul D. Tomlingson

World class performance is the ultimate objective of many maintenance organizations. It marks the organization as a leader in its industry and sets it apart as the ultimate achiever. But what is a “world class” standard and how can it be achieved? Is there a yardstick by which an industrial organization can measure the relative performance of its maintenance activity and compare it with performance levels that universally identify “world class” status? Are there financial formulas, achievements, evaluation techniques or indices that provide this yardstick?

Jan 1, 2006

Instabilities occurred as a result of climate changes caused to investigate the rock behavior dependency to temperature changes, in this paper. In the natural earth condition, the phase transition of pore water has known to be the most effective factor causing different rocks mechanical properties due to temperature changes. So, the temperature range of [-30, 30]°C is selected in laboratory tests of this study. P-wave velocity, unconfined compressive strength (UCS) and elasticity modulus of rocks at different temperatures are studied by developing a temperature adjusting apparatus. The tests were performed on three rock types. The results show that firstly, the temperature reduction and pore fluid freezing improves these rock?s mechanical properties. Secondly, the dependency of rock properties to climate changes depends on the type and shape of its porosity as well as porosity percent. The improvement of rock mechanical properties in jointed rocks exceeds rocks with spherical pores. Finally, maximum changes in rock?s properties occur at [-10, 0]°C, which includes the phase transition of pore fluid. Keywords: Temperature; Rock Mechanical Properties; Pore Fluid; Porosity.

Feb 27, 2013

By Mike Tracy

This section of the Handbook deals with general principles to be evaluated in the development of a mining operation. It addresses the major issues that must be examined to fully evaluate a mining venture. Of course, one of the main topics to be evaluated is mine planning, which is covered in more detail in other sections (13, 17) of the Handbook and should be referenced in mine development projects. The topics to be discussed in this introduction include equipment and supplies, infrastructure, utilities, and project management. In any of the aspects mentioned, the current existing conditions at or near the mine site must be evaluated. This will include assessment of current use of utilities, infrastructure, housing, equipment suppliers, etc., as well as anticipated growth, both in the supply aspect of these systems as well as projected usage on these systems. After full assessment of both these aspects, an evaluation must be made as to the requirements the project will place on these items. Assessment must be made as to any up-grades required to bring the project on line, what impact the project will have on existing or expanded systems, and anticipated future growth impacts on support systems not only of the project but of other surrounding industry and urban devel-opment

Jan 1, 2008

By J. Winterton

Cripple Creek and Victor Gold Mining Co. is developing a full-scale pad injection program as part of the overall operational plan for the Valley Leach Facility. As part of the development process the mechanics of the injection methodology are evaluated in the context of physical injection measurements, outcome from geophysical monitoring, and gold leaching theory. The results indicate that hydraulic fracturing analogies advanced heretofore do not accurately describe injection phenomena in unconsolidated and noncohesive material typical of leach pads. A new interpretation is presented and extended to define operational strategies for maximizing gold production.

Feb 27, 2013

By H. A. Taylor

Graphite is elemental carbon that crystallizes in the hexagonal system as six-sided platelets. It occurs naturally and is mined. And it can be made artificially from petroleum coke in the form of shapes (electrodes) and powders. The market for most kinds of graphite in most end-uses was good in 2004. The 2005 graphite market looks positive. The major graphite prices, as given in Industrial Minerals, remained unchanged throughout the year. The preliminary 2004 U.S. Geological Survey (USGS) prices for natural graphite showed almost no change for crystalline flake. They were $600/t ($544/st) in 2004 and$622/t ($564/st) in 2003. Mexican amorphous graphite was almost unchanged at $150/t ($136/st) in 2004 from$152/t ($138/st) in 2003.

Jan 1, 2005

By Maurus Seet Hong Hua

Introduction Coal has always been China's predominant energy resource. The country ranks among the three richest countries in coal reserves in the world, next to the US and the Soviet Union. According to China's Ministry of Coal Industry (MCI), coal accounted for about 72% of the total national energy consumption. Despite efforts to increase the output of oil and hydropower, coal is predicted to remain dominant on the energy scene by increasing its share to 77% by the turn of the century. To match the rapid growth in the agricultural and industrial sectors, MCI has targeted the coal industry to double coal output from 600 Mt/a (660 million stpy) in 1981 to 1.2 Gt/a (1.3 billion stpy) by the year 2000. How is this goal to be achieved? According to MCI, it will be accomplished by: • building new underground and surface mines with a total output of 400 Mt/a (440 million stpy); • increasing the output of existing state-controlled mines from the present 344 Mt/a (368 million stpy) to 400 Mt/a (440 million stpy); and • developing and increasing the output of small, local mines run by province, county, and production brigade from the present 276 Mt/a (304 million stpy) to 400 Mt/a (440 million stpy). Building new underground and surface mines New underground coal mines will be developed in areas where the coal industry has already made headway and infrastructures currently exist. This is to optimize hardpressed capital spending on investment. Ten existing coal production bases were selected in nine different provinces that met these requirements. The underground mines scheduled to be constructed in stages at he existing coal production bases will have a total output of 200 Mt/a (220 million stpy) by the end of the century. Regarding surface mines, four mines in the Inner Mongolia Autonomous Region and one in Shanxi province have been earmarked for construction during the same period. By the year 2000, these surface mines are expected to produce 200 Mt/a (220 million stpy). Foreign equipment, machinery, and surface mine stripping technology were all involved in different degrees in the development of the five new surface mines. Some have signed joint venture agreements. Occidental Petroleum Corp. is in a joint venture with China in developing Ping-shou's 15 Mt/a (16.5 million stpy) Antaibao No. 1 open-pit. The Shentou power station, situated nearby, is anticipated to consume 3.2 Mt/a (3.5 million stpy) of the coal it produces. Some is designated for export. Increasing output There are 554 state-controlled mines that have been in operation since before 1980. They produce 344 Mt/a (379 million stpy). To increase capacity, MCI has laid out some guidelines. • Coal prospecting near existing mines must be given top priority and intensified so that workable reserves can be increased. This would lengthen the mines' useful life. • Many mines and slopes that were constructed during the 1950s are very small and densely populated. These small mines and slopes are generally very short along the strike. As a result, coal faces and levels require frequent

Jan 3, 1986

By G. J. Koons, J. L. Uhrie

Field density studies carried out at the Phelps Dodge Chino Mine have found that truck-induced compaction is limited to the upper 2.4 meters (8 feet) of an individual lift. Hydraulic properties of material compacted to field densities were determined in a laboratory setting and saturated flow models were then run, simulating the effect of compacted zones within a stockpile. Modeling shows that compaction can effectively prevent solution flow through large portions of the stockpile, implying that great care must be taken to ensure that ripping is carried out to a full depth of at least 2.4 meters (8 feet) across the entire stockpile to achieve uniform solution flow. Uniform solution flow will result in maximum leach recovery.

Jan 1, 2000

By T. Y. Yan

O2, NaCl03, H202, NaOCI and Ce+4 have been examined as oxidants in an alkaline carbonate system for uranium in situ leaching. The South Texas and New Mexico ores contained up to 2.6 meq/g of reducing compounds that consume oxidants in the leaching operation. Leaching rates did not increase linearly with the oxidation potential of the oxidants. A mild oxidant can be used to maximize uranium oxidation selectivity and oxidant efficiency. 02 can oxidize most of the uranium mineral with an adequate rate and high oxidant efficiency.

Jan 1, 1993

By MATT RENAUD, Mustafa Kumral

As high-quality mineral deposits are thoroughly exploited, mines of the future will have to move towards more remote and lower quality projects. With these projects comes an increased business risk to the operator. Even now, mining companies often turn to foreign countries for new deposits to produce, introducing the concept of country risk into their portfolio. Furthermore, feasibility studies often fail to accurately quantify the risks associated with various projects, and as such, this study proposes a technique of risk quantification which can both aid mining companies to evaluate the viability of investment and assist in risk disclosure to public investors for the mining industry of the future. This paper aims to quantify the effects of country risk on the valuation of potential mining projects, using a combination of modular and risk-weighting techniques to evaluate the country risk premium (CRP) required to obtain capital for operation of risky foreign mining projects. The techniques proposed in this paper are demonstrated using fictional examples and then evaluated for accuracy against a recently developed debt-funded precious metal project in a country in the Americas.

Sep 30, 2021

By S. L. Lebo, J. D. Gargulak

Lignin, the second most abundant natural polymer and bi-product of the pulp and paper industry, has been commercially available in a number of forms since 1940. This growing industry is fueled by demand in traditional applications. Reagents that offer unique solutions in various mineral process applications are examples of advanced uses that also fuel growth. These applications include flotation reagents in fluorspar, bastnäsite and potash, as well as in the zinc pressure leach process. Due to the fact that no concerted effort has been made to find applications for modified lignosulfonates, it is quite possible that this natural material will find use in other benefication processes.

Jan 1, 2002

By C. K. Kocsis

A study was undertaken to evaluate the thermal environment and determine the contributing heat sources within the existing 153 Orebody of Coleman/McCreedy East Mine which would then enable the prediction of the climatic conditions in the mine?s future 170 Orebody. The study entailed continuously monitoring, for a 2-week period, the dry-bulb temperature, humidity and barometric pressure along the existing intake airways from surface down to the 4810 Level and throughout an active mining area on that level. Furthermore, the mining activities and associated equipment that could be responsible for any changes in the temperature and humidity conditions within this mining area were also monitored. These data were then used to develop and validate a climatic simulation of the mine?s mechanized cut and fill mining method. This climatic model was then transposed to the future 5700 Level in the deeper 170 Orebody, to determine the environmental conditions within its production workings and along the main haulage route ascending from that area. Based upon the simulations performed it was shown that the level of ventilation planned for the new orebody should be able to maintain adequate environmental conditions. However, this study did emphasize the importance of the appropriate distribution of airflow in workplaces that used auxiliary ventilation in order to sustain a suitable thermal environment.

Jan 1, 2009

By M. Li, J. D. Miller

Many technology problems must be solved if we are to continue to produce phosphate at our current rate of consumption. The U.S. produces at least 25% of the world's phosphate, 40 million tons of phosphate rock per annum with most of the production coming from Florida. Of particular concern are improved separation efficiency and the ability to treat new dolomitic resources. Phosphate flotation technology needs include: 1. Simplification of the standard flowsheet 2. Improved recovery of coarse phosphate 3. Selective flotation for phosphate recovery from dolomitic resources Preliminary results, including tests on plant feed from Florida show that these objectives may be achieved with a new collector chemistry depending on the specific circumstances. The effectiveness of the new collector chemistry has been demonstrated by the preliminary results from single stage flotation experiments both at the University of Utah laboratories and at Florida Institute of Phosphate Research (FIPR) laboratories. In the best case, from these experiments with low grade (5% P2O5) coarse feed (16x35 mesh), a single stage phosphate recovery of 95 % was achieved with a concentrate grade of 31 % P2O5. Such a separation efficiency could not be achieved using the traditional fatty acid/fuel oil collector. Based on these results it seems that a one step process may be possible for phosphate flotation and a research program is justified for the development of this new flotation strategy.

Jan 1, 2001