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By Geoffrey S. Plumlee

The Summitville gold mine, located in southwestern Colorado, received tremendous publicity in the 1980's and 1990's for leaks of cyanide solutions from its heap leach facility. As is typical with cyanide spills, real time, geochemically rigorous assessments of the environmental effects were not performed. Past United States Geological Survey (USGS) research used simple mixing experiments to model the influx of alkaline cyanide heap leach solutions from Summitville into a nearby stream, whose waters were highly acidic due to severe acid-rock drainage (ARD) from the mine. These experiments indicated WAD cyanide rapidly degraded due to formation of Fe-Cu-CN solids and lesser HCN volatilization. The alkaline heap leach solutions also precipitated hydrous iron-and aluminum, oxides and hydroxysulfates (iron and aluminum 'supplied by the acid. rock drainage (ARD]), which then sorbed copper and other heavy metals from the ARD. These results indicate that mixing of cyanide heap leach solutions with ARD may be a cost-effective remedial method at mine sites where treatment of both is required. New experiments are currently in progress to further refine a potential remedial process.

Jan 1, 1998

By P. G. Gresse

The Orange-Vaal River system is known to be the primary secondary source for alluvial diamond deposits in the northern Cape and along the west coast of Namaqualand. The higher order sources for diamonds contained within this system are still not defined entirely to satisfaction, but certainly include kimberlite pipes exposed in the catchment regions of these rivers. The focus of alluvial diamond mining along the Orange-Vaal system recently changed from the traditional areas in the upper catchment regions?the Barkly West, Christiana, Bloemhof, Wolmaranstad, Schweizer-Reineke region, and the lower regions near the mouth of the Orange River at Baken, Alexander Bay and Oranjemund, to the area between Douglas and Prieska?the so-called mid-Orange region (Figure 1).

Jan 1, 2003

Devitrification of a glassy volcanic ash equivalent to an alkaline trachyte in composition has resulted in the formation of an interstratified illite-montmorillonite with an 1:1\1 content of 1:4 as the principal clay mineral.A high concentration of potassium ions and a deficiency of magnesium ions favoured the formation of the potassium-bentonite.A poorly ordered mica mineral, equivalent to illite, was produced by weathering of potassic feldspar. Subsequent degradation of the illite through the loss of potassium was responsible for the formation of several interstratified minerals with very approximate 1:1\1 contents of 4: I as minor components.Other authigenic minerals present in small amounts were u-cristobalite, sepiolite, and the zeolite clinopitolite.The non-swelling character of the potassium-bentonite makes it economically unattractive...

Jan 1, 1967

By Enrique Monge

El presente artículo describe la importancia del acero en Estados Unidos de Norteamérica como el más grande productor de acero del mundo. Los principales minerales utilizados son los óxidos de hierro como la hematita, jimonita y magnetita. El mineral de fierro es extraído por el método de tajeo abierto, palas mecánicas separan la cubierta de detritus y cargan el mineral directamente a camiones o carros de ferrocarril. En Alabama y a lo largo de los Montes Apalaches existen depósitos de fierro sedimentario de formación más reciente que los del Lago Superior, produciendo cerca de 6% de la producción total de los Estados Unidos en 1963. Otros tipos de minerales de fierro explotados en los Estados Unidos son las magnetitas de New York, New Jersey, Pennsylvania y las magnetitas y hematitas de Missouri, Utah, Wyoming y California.

Nov 1, 1957

By A. Bascetin

One very important aspect of mining is deciding what material in a deposit is worth mining and processing, versus what material should be considered waste. This decision is summarized by the cut-off grade policy. The cut-off grade strategy for an open pit mine influences the annual cash flows and affects the net present value of a project. The optimization of cut-off grade strategy requires the knowledge of detailed operational costs, mining sequence, mining operation, processing, and product constraints, as well as the grade distribution of a given deposit defined by pit, phase, and different material types. Cut-off grade optimization algorithms have been developed in the past. The most common criteria used in cut-off grade optimization is to maximize the net present value (NPV). This paper describes the determination of a cut-off grade strategy based on Lane?s algorithm adding an optimization factor based on the generalized reduced gradient (GRG) algorithm to maximize the project?s NPV. The introduced algorithm is a windows based program developed at Virginia Tech that is based on a series of Visual Basic routines within a spreadsheet environment (Excel).The benefits of the methodology are demonstrated using a hypothetical case study. Keywords: Cut-off grade optimization, net present value maximization, generalized reduced gradient algorithm method.

Jan 1, 2007

By Jean-Pierre Hamelin

Ground movements induced by underground excavation are always of critical concern, particularly in urban areas. Compensation grouting now appears as a safe means to control these movements. The paper presents new advanced systems developed by the specialist contractor to bring, at all stages of the project, an efficient control of operations and presents a case history taken from the project at Tren Urbano, Rio Piedras Section, constructed beneath an historic commercial section of San Juan de Puerto Rico.

Jan 1, 2000

By S. Bellec, P. Champagne, J. Châteauneuf, A. Berton, S. Fortier

"The start-up of new plants, extending from the commissioning of equipment to the production ramp-up, is a critical period where the processing circuit operation must be done in a structured and well controlled way to enable the gradual, safe and rapid achievement of production targets. The magnitude of the many risks associated with this pivotal period is accentuated in the actual context of low commodity prices. However, the implementation of a method that analyzes risks associated with a start-up, their probability of occurrence and their impacts leads to the identification of a series of preventive actions that can be applied in order to reduce potential negative impacts.Soutex has been involved in numerous start-ups over the last few years and has developed a structured methodology to assess this crucial period, maximize the pre-start-up preparation, ensure a smoother and safer ramp-up period and minimize the time needed before reaching commercial production.This paper describes a method to identify preventive actions to apply in order to reduce risks related to a plant start-up. Then, the various steps of the method are demonstrated using the industrial case study of the Canadian Malartic gold plant situated in Abitibi, Québec. The specific preventive actions, during start-up, the organisational measures and the ramp-up plan are detailed as they were effectively achieved. Finally, the post start-up actions are presented as well as some key results illustrating the achievement of their prior defined objectives.IntroductionPlanning a new plant or new circuit start-up in a mine installation involves various risks, both at the economical and safety levels. Unprepared staff and equipment can lead to safety issues that could threaten plant staff as well as the environment. Moreover, a poorly prepared start-up could often lead to equipment break-down, production stoppages and delays, leading to important economic impacts, delaying commercial production and therefore affecting directly the profitability of mining projects.It is common in the industry to have structured commissioning procedures for major equipment taken separately. Technical personnel from the equipment manufacturing company would usually come on site in order to perform the pre-operation verification, dry runs and the first hours of operations. This kind of assistance is usually focussed on one piece of equipment and neglects the interactions between the various equipment of the production chain. The commissioning phase is usually maintenance oriented and the information given by the manufacturing representative seldomly flows through the operation staff (in the case of this paper, the denomination “staff” refers to both managing and operating employees). The global process is usually not taken into consideration by the technical personnel sent on-site by the manufacturer during the commissioning phase. Many papers can be found describing the commissioning of new equipment focussing on the technology (Côté and Adante (2009), Wells et al (2007)) but without dealing with its integration process in the complete production chain."

Jan 1, 2016

By A. Broussaud

An original methodology has been developed for steady state simulation of selective grinding and mineral liberation in rod and ball mills. Three fundamental aspects of the methodology are presented successively : modeling ore texture, modeling grinding and its selectivity, and modeling mineral liberation. The methodology for modeling ore texture includes the conversion of 2D data into 3D reconstructed information and the use of the BILCO coherent material balance software. The models for grinding Simulation are classified into three levels, corresponding to three levels of available experimental data. All models account for grinding selectivity and for variations of engineering para-meters and operating conditions. An algorithm has been introduced to forecast mineral liberation, compatible with accurate simulation of selective grinding, which generates reasonable results.

Jan 1, 1987

By J. C. Yingling, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Much of the land reclaimed since enactment of the 1977 Surface Mining Control and Reclamation Act is over-compacted. Research has shown that excessive compaction in replaced growing media is detrimental to establishment of trees. If trees are to be grown on reclaimed surface mined sites, something must be done to alleviate this excessive compaction. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed growing media. The University of Kentucky has developed test cells on reclaimed sites at a surface mine in eastern Kentucky to determine the impact of tillage (ripping) on soil compaction and tree survival rate. The ripping methods being evaluated include shallow tillage using conventional farm equipment and deep tillage using a dozer with a ripping arm. The impact of organic soil supplements on soil physical properties and tree survival rates is also being evaluated at the site. The organic soil supplements being evaluated include application of hardwood bark and application of straw and mulch. Each test cell has been planted with various species of trees, and for the first two years, data have been collected at these test cells for soil dry bulk density, penetration depth and resistance, and survival rate of trees. These data are currently being correlated to determine how ripping and the application of organic soil supplements affects the relationship between soil compaction and tree survival rate.

Jan 1, 2002

ONE DAY IN the mid-1880s, in a suburb 0f Pittsburgh, Pennsylvania, there dismounted from a train the two foremost leaders of the day in the coal and steel industries-Andrew Carnegie and H. C. Frick. Their attention was drawn to a well-loaded car of coke, which their experienced eyes recognized as a superior product. "I'll bet you that coke is from the H. C. Frick Coke Company," Mr. Frick challenged. "I'll bet it was shipped by my company." In a spirit of fun Mr. Carnegie accepted the wager. Mr. Frick lost the bet: the coke had come from M0rewood, one of three sites being operated under the direction of a young entrepreneur, Erskine Ramsay. If Mr. Frick's confidence was somewhat dented by this occurrence, the responsibility was his own. He himself had opened the way for Erskine Ramsay to become the youngest of mine superintendents; and he had dispersed all dissension regarding his choice with the words : "I'm not interested in his years, I'm interested in his record. He makes more coke in an oven than any other superintendent. And I'll take 'em out 0f the cradle if they can make coke... Suppose he is only twenty years old? ... The d --- kid is a genius, I tell you." Erskine Ramsay was to follow in the tradition of Carnegie and Frick. Not only was he ambitious and a worker his background had prepared him for it. Coal mining was in the Ramsay blood. His father, Robert Ramsay, of whom the son once stated that he had no superior as coal mining and mechanical engineer in this country, once accounted in these words for the phenomenal accomplishments which had attached to the name "It does no harm to belong to a family of mining engineers who are just as good as any in America-if it is myself that says it." Anyone acquainted with Robert Ramsay's character realized that he was not given to overstatement. And the above-mentioned Mr. Carnegie encountered young Ramsay again, a few years later in his career, and wrote of him to young Erskine's father, that he was "going to be a credit `tae us a' " (a quotation from Robert Burns.) Nor have Mr. Ramsay's achievements been identified exclusively with the industrial field in which he early asserted himself. He has been an inventor whose techniques in mining engineering have received international recognition. As an investor of foresight, he has benefitted others immeasurably, as well as himself, being an influential factor in the upbuilding of several communities in his chosen and well-loved adopted home state of Alabama since 1887. He is a philanthropist whose benefactions have run into millions, the chief beneficiaries being educational and charitable institutions. Amidst his accomplishments the lighter side of life has not been neglected and he is known for his hospitality, his

Jan 1, 1953

By D. J. Reddish

An understanding of the mechanisms that cause large seismic events in a deep mine provides a foundation for designing effective measures to reduce the incidence of these events, as well as reduce the potential for damage arising from these events. The work described in this paper focuses analytical efforts on major recognizable and controllable factors that influence mining-induced seismicity and serves to screen out many of the more random aspects of individual events. Information used in this study was developed in the course of a long-standing rock burst research program conducted by the U. S. Bureau of Mines in cooperation with mines in the Coeur d'Alene Mining District and regional universities. Information was collected on 39 seismic events having local magnitudes greater than 2.5 that occurred between 1989 and 1994. Five major types of events were developed from these data that describe all but two of the 39 large events. The characteristic mechanisms, tint-motion pattern, damage pattern, and relationships to mining and major geologic structures were defined for each type of event. This information provides a foundation for assessing whether or not changes in mining activity aimed at reducing one type of rock burst will increase the incidence of other types.

Jan 1, 1996

By Clifford B. Farris

The natural cementation strength of retorted oil shale is the focus of this investigation. The optimum retorting temperature and residence time to obtain natural cementation strength in retorted Green River oil shale from western Colorado were determined as follows: [Optimum Conditions for Natural Cementation Maximum Residence Obtained Retorting Time at Compressive Mode of Temperature Temperature Strength' Retorting °F °C hr psikg/cm-2 Direct 1,520 822 2.0 270 19.0 Indirect 1,530 832 2.9 325 22.8] 1 Scattered samples were tested at strengths as high as 463 psi (32.6 k /cm 2) (Run 8, indirect mode) and 406 psi (28.5 kg/cm2) (Run 48, direct mode), but these high strengths were not confirmed by nearby tests. Minus 0.5-inch (1.3-cm) Green River oil shale was heated in a differential retort under conditions simulating potential full-scale retorting processes. The variables investigated were retorting temperature, residence time, retorting mode, and shale grade. Samples of the retorted Green River oil shale were moistened to optimum plus 2% (25%) moisture, compacted to 95% Proctor density, sealed and cured at 100°F (38° C) for up to 40 days. Lower curing temperatures, which are likely in the field, would probably result in significantly slower development of cementation strength, and might lower the ultimate strength developed. However, these effects were not studied in this project. The cured samples were tested for compressive strength, and correlative equations were developed for the increase of compressive strength with curing time as a function of retorting temperatures and residence time. Petrographic analysis indicated that the cementing mechanisms may be the interlocking growth of acicular hydrated calcium aluminum sulfate crystals between the contacts of retorted shale fragments. Samples of the retorted shale were also tested for optimum Proctor density and moisture. Permeability and quality of the leachate of shale from typical runs were determined. The effect of use of retort rather than tap water on compressive strength and leachate after curing was determined. The retorted shale effectively filtered several mineral constituents from the retort water.

Jan 1, 1979

The prime objective of geometallurgy is to improve the profitability of mines through the use of spatial models of rock properties that have a significant impact on value. Although a key property is the grade of the component of interest, because it directly influences the revenue from saleable material, increasingly attention is being focused on other attributes. These 'non-grade' variables may have a less direct, but equally profound impact on value, either by reducing potential revenue (eg lowering recovery, deleterious elements, etc) or increasing mining or treatment costs (eg comminution, grindability, throughput, reagent use, etc). Collectively, these variables have been described as 'geometallurgical'. There are three main areas of activity required to realise the value of geometallurgy: 1. acquisition of appropriate data through sampling and measurement, 2. building spatial models of geometallurgical variables, and 3. using these models to optimise value. Each of these is built on the foundation of the preceding step. In building reliable spatial models, it is critical that the amount of error introduced to data by the sampling and measurement processes is understood and quantified, in order that the inherent variability of the component of interest can also be properly understood. Management of the quality of grade variables is now applied (with different levels of diligence and success) across nearly all sectors of the mining industry, not least because of the necessity to adhere to Codes of practice (eg JORC, 2004). The necessity for quality management and at least the broad framework of what to do in practice is reasonably understood by many relevant professionals. There are also a number of tools, including software products, statistical analyses and presentation formats, available for those managing grade data. It is also abundantly clear, that in many cases people have little understanding of why they are doing particular quality control activities, or how to sensibly interpret the results. The same is not true for many geometallurgical variables. In almost all instances the authors have seen, the magnitude of sampling and analytical/measurement error variance embedded in geometallurgical test data is untested and unknown. This is partly because until relatively recently, metallurgical data has mainly been collected for the purpose of process and mill design, with few, expensive tests carried out on 'average' samples of the orebody. Increasingly however, there is a move towards collection of much larger data sets from spatially distributed sampling, and thus a growing necessity to understand the errors inherent in both sampling and analysis of these types of variables, and how to manage them. In order to understand how the quality management practices applied to grade variables can be extended to geometallurgical variables, it is essential to understand the theoretical foundation that supports these practices. This requires an analysis of the concepts that underpin the 'principles of additivity' (Matheron, 1963), the 'theory of sampling' (Gy, 1982, Pitard, 1993), and 'statistical process control' (Shewhart, 1930). Relevant concepts are then integrated to form a foundation to develop methods to improve the quality management of geometallurgical variables. Application of this framework will significantly increase the integrity of geometallurgical data, the reliability of geometallurgical models and ultimately the value derived from implementing geometallurgy. This is an ABSTRACT ONLY no paper was prepared for this presentation.

Mar 1, 2010

As opposed to a prescriptive-based design, a performance-based fire-protection system design allows the system planner the flexibility in choosing specific method, materials and design tools to achieve a preset goal. A different approach in fire protection and a powerful addition to existing method, the system has been around for many years, and has gone through numerous improvements. Despite its popularity in the building industry, it has not been introduced to the mining industry yet. As mines get deeper, increases in size and complication, mine fire safety system will also become increasingly challenging, a new and proven system should be able to great potential to eradicate many of the problems that are either unsolvable or cost-prohibitive with the traditional method. With increasing globalization and international exchange with other major mining countries a common language/practice also make the performance-based design method a desirable feature in mine fire safety system. This paper will first define a performance-based system, step-by-step design methods, likely impacts on fire-protection practices and possible challenges in implementing the system in US underground mines.

Jan 1, 2011

By Richard E. Gray

Subsidence due to coal mining is poorly understood by non-specialists. This has led to numerous misconceptions and myths based on limited observations and lack of knowledge. The three most common are: 1. Mine maps are inaccurate. 2. Deep mines are not a problem. 3. If no subsidence has occurred for many years after mining, there is no risk of future subsidence. Maps are important during mining and most are carefully prepared. Future use to evaluate conditions at mine level often includes drilling to confirm what the map shows. Usually, little or no effort is made to tie the surface survey of the property to the mine survey, to conduct a well designed drilling program to confirm the mine map, or to drill test borings vertically. When a mine entry is encountered rather than a coal pillar, or vice versa, and conditions at mine level appear different than anticipated, the first reaction is the mine map is inaccurate. The idea of a safe depth from subsidence is often based on the false premise that mining results in sufficient breakup of the overlying rock strata that bulking compensates for the coal extracted. The safe depth idea first appeared in the literature about 1880 and remained prevalent well into this century. Sadly, it is still encountered. The modern understanding of fragmentation of the immediate mine roof with the overlying beds sagging down on the broken roof rock was first described in 1900. With full extraction mining, either longwall or retreat room and pillar, surface subsidence occurs regardless of the depth of the mine. Subsidence over longwall mines at depths of 2000 feet can be 90 percent of the mined seam thickness. Numerous studies of undermined sites conclude that mining occurred many years ago and since no subsidence has occurred, there is no risk of future movement. This is true if sufficient coal pillars have been left to support the overlying strata. However, every year subsidence occurs over mines that have been closed for 100 years or more. In a study of subsidence incidents over the Pittsburgh Coal, the senior authors found that 50 percent of the incidents occurred above mines that had been closed for at least 50 years and 10 percent over mines closed for at least 80 years.

Jan 1, 1996

By Sydney C. Mifflen

COAL MINING, with its some 15,000 employees, is directly responsible for the livelihood of one-fifth of the population of the Province of Nova Scotia and indirectly so for that of possibly another fifth. Deposits of coal are known and worked in four counties of the Province, from which is being produced yearly tonnages as noted below: Cumberland County 750,000 tons Piccou County 400,000 tons Inverness County 100,000 tons Cape Breton County 5,250,000 tons TOTAL FOR NOVA SCOTIA 6,500,000 tons Production in Cape Breton county is entirely from the one source, the Sydney coalfield, and not only is this field the most important in respect to output, as is disclosed above, but it is also the largest presently known deposit in the Province and holds the greatest tonnage yet in reserve for future mining. In the light of the above more or less generally known facts, it is trite to remark on the importance of the Sydney coalfield in the internal economy of the Province. On the other hand, not nearly as well-known nor as frankly recognized is its significance in the national life of Canada, for from this field is produced not only 80 per cent of the Nova Scotia coal but over 40 per cent of all coal mined in the Dominion. Another noteworthy comparison can be made from the fact that the Sydney field contributes 22 per cent of all the bituminous coal consumed in Canada, the remainder being made up of 7 per cent mined elsewhere in Nova Scotia, 27 per cent from other parts of Canada (British Columbia and Alberta, principally), while the remaining 44 per cent is imported, practically wholly, from the United States of America.

Jan 1, 1941

By Becerra J. O

HYL developed a direct reduction process (DR) that does not require a reformer; it is called self-reforming process. Typically, direct reduction processes based on natural gas utilise a reformer unit to transform the natural gas into reducing agents (hydrogen and carbon monoxide). The reforming reactions are: CH4+H20-?3H2+CO CH4 + CO2 - 2H2 + 2CO These reforming units require a catalyst agent to promote the kinetics of the reforming reactions. The catalyst for these reactions is typically a metallic element such as nickel in a ceramic matrix; iron is also an excellent catalyst for the reforming reactions.

Jan 1, 1999

By M. Churchill, V. R. Degner

"Over the past two decades, declining ore body grades, increased operating costs and increased construction costs have provided an incentive for the development of progressively larger flotation machines. As a consequence, the 60 to 100 cubic foot flotation machine of the l950's and l960's is being rapidly replaced by large volume machines, with a resulting improvement in the flotation machine specific capacity (TPH processed per square foot floor space), specific power (HP per TPH processed) and process control simplicity. The recent development, and satisfactory plant evaluation, of the WEMCO 1000 cubic foot flotation machine provides the means by which further economic and operating advantages may be incorporated in high tonnage mill applications.The systematic development of the large 1000 cubic foot flotation machine, and its subsequent performance evaluation in beneficiating metalliferous ores (copper, zinc and iron) will be reviewed in this paper and recently completed plant results will also be provided."

Jan 1, 1982

By Chen Xia

Iron separation from rare earth elements has always been an essential operation in almost all steps of rare earth element recovery and purification processes. As RE3+ and Fe3+ behave similarly in many operations the separation can sometime be either difficult or cost-inefficient. This article attempts to review the methods and options for removing the iron content within the process, with the focus on the existing or proposed precipitation and solvent extraction technologies. The precipitation of iron from REE solution as iron hydroxide, jarosite, goethite, hematite, or phosphate are briefly introduced. Methods for precipitating REE from solutions leaving iron impurities in the aqueous phase are discussed. Some proposed solvent extraction flow sheets for separating iron from REE are conceptually reviewed in this article.

Jan 1, 2013

By A. Cichowicz

The objective of this work is to quantify the effect of the rock mass surrounding a stope or a tunnel on the seismic signal so that the rockburst damage on the excavation can be derived. It has been shown that the transfer function of rock mass surrounding an excavation can be modelled using a damped oscillator. The method of estimating the transfer function is extended in this paper. The parameters of a damped oscillator are estimated using inversion techniques and the transfer function is modelled as a time-varying system. The technique is tested on data acquired at three different sites in two deep gold mines. Employment of a modal model of the transfer function was suitable in two cases. Application of this technique is essential to track the time variation of the natural frequency during ground motion caused by a seismic event.

Jan 1, 1999