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By S. K. Kawatra

It is common in coal-cleaning operations to produce a fine waste stream which contains a considerable amount of coal, but which is not economical to recover both because it is mixed with large amounts of difficult-to-remove clay slimes, and because the fines are often heavily oxidized. Conventional froth flotation machines cannot produce an acceptable product from such material in a single stage of flotation, and even flotation columns often have difficulty cleaning this type of feed. A new type of flotation column was designed specifically to deal with these problems, and was installed and tested in a coal-cleaning plant in Ohio. The feed coal contained 39.8% ash as fine clay, and 2.83% total sulfur, and was 80% passing 176 micrometers. The coal was a thickener product which had oxidized for some time, and was very difficult to float. However, using the new column it was possible to recover up to 85% of the calorific value in a product containing less than 11% ash, and up to 60% of the calorific value in a product of less that 8% ash. The bulk of the pyritic sulfur was rejected from the coal as well. Multistage flotation tests showed that the flotation column was able, in a single stage, to produce the best froth flotation product that it was possible to recover from this coal.

Jan 1, 1994

By M. Deutsch, E. González, M. Williams

"There is uncertainty in ultimate pit limits due to geologic variation and unpredictable economic landscapes. In this work we show how this uncertainty affects the ultimate pit and how it can be analyzed to improve the mine planning process. A stochastic framework using geostatistical simulation and parametric analysis is used to model the effects of geologic and economic variation on ultimate pit limits and overall project economics. This analysis is made possible by a new, highly efficient pit optimization implementation which can be automated and set up to calculate ultimate pits for hundreds of different scenarios in a matter of hours. Quantifying ultimate pit uncertainty early in the mine planning process allows mining engineers to make informed decisions regarding infrastructure placement, and to mitigate the possibility of incurring substantial costs relocating critical mine facilities. INTRODUCTION The mining industry is increasingly concerned with the effects of risk and uncertainty. Uncertain prices, unpredictable global markets, and unknown foreign exchange rates can alter the economic viability of a mining project in substantial ways. This economic uncertainty is compounded by geologic uncertainty. The extent and quality of any given deposit cannot be fully measured and is not known before consequential decisions must be made. These two sources of uncertainty are responsible for the majority of deviation between what happens during operation and what was initially planned. Understanding and explicitly quantifying this uncertainty will lead to better decision making and allow mining engineers and investors to be aware of what may occur. It is unrealistic to believe that one model, estimated from sparse measurements, is enough to capture both geologic and economic uncertainty and allow for optimal decisions. The entire breadth of uncertainty should be considered, as both upside and downside risks have large impacts on the investment potential and operational efficiency of mining projects. The workflow presented here uses Monte Carlo simulation and parametric analysis together to explicitly analyze the breadth of geologic and economic uncertainty as it applies to ultimate pit calculation and long range mine planning."

Jan 1, 2015

By Panshi Xie, Yan Chen, Shaogang Wu, Yang Hang

In order to realize the intelligent mining of coal seam with large dip Angle, this paper adopts the methods of large proportion variable Angle loading threedimensional physical simulation experiment, numerical simulation and field measurement with digital twin technology. The hydraulic support with large dip Angle and large mining height is used as the prototype to design the physical entity model of 1:5 hydraulic support, combined with modeling and graphics rendering technology. Angle, displacement and load sensors were selected and placed to realize the data channel between the lower machine and the upper computer of the digital twin system, so that the position and load data of the physical entity model and the twin model of the laboratory hydraulic support could be shared in real time. Moreover, the multi-dimensional dynamic and static load transfer law and the position evolution characteristics of the support and surrounding rock under different inclination angles were analyzed. The results show that: with the increase of the Angle of the working face, first, the initial support force required by the support decreases, and the damage degree of the roof increases; When the roof is soft, the lifting operation can avoid the instability of the support to a certain extent. Second, under the action of positive pressure, the load of the top beam under different angles is balanced; Under the backpushing action, the load in the upper inclined area of the shield beam increases gradually, while the load in the lower inclined area decreases gradually. Under the lateral push, the load changes periodically, and the load in each cycle is increased compared with that in the previous cycle. Third, the numerical simulation analysis shows that the load on the lower bracket is less than that on the upper bracket, and the load on the bottom of all the columns is greater than that on the middle and upper brackets. In order to reduce the impact of the columns on the bottom plate or the base, it is necessary to improve the anti-subsidence ability of the base. Finally, according to the research results, the improvement and optimization measures of the support are put forward, and the field test shows that these measures effectively solve the problems of sinking, sliding and tipping of the support in the working face with large inclination Angle, and obtain good application results.

Feb 1, 2024

By Luis R. Bittencourt

Research efforts have been made to characterize a refractory Brazilian bauxite ore composed basically of gibbsite, kaolinite and quartz. Detailed polished-section microprobe analysis of the unbroken ore has been used to describe the liberation characteristics and the association between mineral phases. The linear grade distributions for selected particle size fractions were determined by means? of a particular implementation of King's Random Fracture Model that uses the exponential model for the distribution of linear intercepts through both dispersed (kaolinite) and continuous (gibbsite) phases. The corresponding volumetric grade distributions were then determined by means of a constrained optimization technique for the solution of the transformation equation. Batch flotation experiments were carried out to determine the kinetics for particles of different sizes and the results correlated with the liberation spectrum for each size class.

Jan 1, 1991

By Juan P. Camus, Sergio G. Jarpa

INTRODUCTION Chuquicamata mine is a large copper open pit located in the north of Chile. It has been in production for more than 80 years and now is in the later stages of its life with declining grades and increasing haul distances. As any old mine with long established organizations and procedures, it has faced one of the most difficult managerial problems: to conduct changes. Since 1994, the new management team has been devoted to a modernization pro- gram focused mainly in restructuring business operations. downsizing the labor force and introducing a mine planning pro- cess consistent with the company's goal. The explicit identification of the latter issue has been made because of the management’s conviction about the importance of it in the profitability of the business. The mine planning process at Chuquicamata mine has evolved from an old manual technique towards a modern computarized system, however the fundamental aspects and the procedures involved in this process have been the same. For in- stance, the cutoff grades policy has not changed during the last said 20 years, regardless of the changes to grade distribution, commodity prices, plant capacities, etc. To review and rethink this process, the strategy was to work with a small group of inside engineers and the management in order to interact with several mining consulting firms. The idea was to open a discussion about the fundamental principles used in the mine planning activities and, at the same time, to explore new ideas to improve the operating practices that have been followed for a long time. Thus, the goal of this paper is to present the mine planning approach that was the result of this work and the improvements that were obtained. THE CHUQUICAMATA MINE The Chuquicamata division is one of the five operations of Codelco and is currently devoted to operating the Chuquicamata mine; a copper open pit, concentrator, smelting and refining complex. It also operates Mina Sur which consists of an open pit mine, a leaching-solvent extraction and electrowinning process. There is also a dump leaching and a Sx-Ew plant for treating the low grade suifide ore (under the cutoff grade) from the Chuquicamata mine. Prior to reviewing the mine planning process, capacities for the Chuquicamata sulfide line were 640 000 tpd of run of mine material, 160 000 tpd of ore and 4 200 tpd of concentrate. This meant a total annual movement of around 230 Mt in the mine and a treatment of 57 Mt in the concentrator with a stripping ratio of approximately 3: 1. The old exploitation strategy consisted of an "open scheme", which means that all benches must have a berm with enough space to allow the traffic of large haulage trucks. This fact implied working with a great flexibility, but the consequences were flat slope angles. One of the reasons for using this operating practice in short term planning was that the grade consistency from the pit has always been a controversial variable. Schedules were designed to meet grade targets accurately and they were modified immediately when deviations become apparent. This reality led to working with a great deal of independent pushbacks and it required flexibility in the traffic system. The cutoff grade policy has been the same for a long time and the figure was 0.5 %CUT either for sulfide or oxide ore. This was the reason why a balance was produced between the mine and the concentrator. The mine is operated principally with benches of 26 m but in the upper part of the pit there are benches of 24 and 30 m. The main production equipment is shovels of 28 and 34 yd3 along with trucks of 200 and 240 st. Regarding the crushing facilities, there are two main systems located inside the pit and an old one in the periphery, close to a stockpile and near the concentrator. In the north part of the pit there is a crusher for waste material and in the north-east area is located the ore crusher facility. Both restrict a significant area of the pit and the mine sequence is considering to move the ore crusher again to the south-east sector where it used to be located. Relating to the waste crusher, the idea is to move it up to a bench near the surface in order to use the same conveyor belt and, at the same time, liberate an important sector. THE MINE PLANNING PROCESS The objective of the mine planning process is to develop a mine plan for the life of the deposit, in harmony and consistent with the company's goal. It includes the origin and destiny of tonnages and grades from the mine(s), along with the necessary resources to carry out this plan such as: fleet requirement, consumable goods, manpower, etc. From the financial point of view, it means to establish the cash flow for each time period of the mine life. That is. the revenue, capital investment and operating cost associated with each period of the plan. The fundamental principles involved in the mine planning pro- cess have been a controversial issue for a long time. One of the reasons for these divergent views could be produced by the difficulty of modeling a complete extraction policy for a geological re- source. This particular problem has to deal with several decision variables that are time dependent. So far, there is no mathematical formulation for managing such a problem, and the approach to solve it is based on a circular analysis combined with certain heuristic tools. So, a global model rather than a formula, requires a clear understanding of mine operations as well as economic theory and its application to a non-renewable resource. In order to manage this complex problem, the mine planning process can be conveniently split off in three stages which are conceptual, feasibility and operational planning. The characteristics of each stage are basically the timeliness in which they are developed and the kind and number of variables involved. Thus, conceptual planning is devoted to the definition of key variables like: the size of the operation, mining method, extraction se-

Jan 1, 1996

By E. H. Smith

St. Joe Minerals Corp., a subsidiary of Fluor Corp., treats high-grade gold, silver, and copper ore at its El Indio plant at an altitude of 4 km in the Chilean Andes. The ore is complex, being a mixture of massive pyrite-enargite and quartz, both containing very fine gold and silver. Treatment produces a copper flotation concentrate containing high levels of gold, silver, and arsenic, and also dore bullion. Part of the flotation concentrate is roasted to remove the arsenic content, and arsenic trioxide is collected as a by-product.

Jan 1, 1987

By W. Blake, J. Whyatt

Sixty years of rock bursting in the Coeur d'Alene district has taught painful lessons and led to a number of practical advances in controlling rock-burst hazards. This paper summarizes these lessons, concentrating on practical measures that have been successfully adopted to reduce hazards. These lessons are explained in the context of district mining history and current understanding of rock-burst phenomena. Overall, the paper provides the practicing mine engineer with an appreciation of rock-burst hazards and an overview of practical measures that can be used to control these hazards in the context of Coeur d'Alene district experience.

Jan 1, 2003

By R. J. Sheets

In 2009, the Gold Quarry openpit mine experienced multiple large-scale slope failures of the upper east highwall that reduced gold ore extraction for nearly 18 months. The slope failures occurred within a weak, consolidated sedimentary sequence that exhibits strength characteristics that are transitional between soil and rock. Instability initiated as mining exposed the lower, high plasticity subunits of the Carlin Formation. This deformation created preferential flow paths that allowed ground water from the upper sandy subunits to infiltrate low-permeability, clay-rich subunits, thereby enhancing deformation of the slope toe, which, in turn, destabilized the upper portion of the highwall. The outcome was a 160 m high slope failure that had a lateral run-out of 850 m. The effort to return the pit to ore production required geotechnical and hydrogeological investigations and the preliminary remediation mining activity to be concurrent. This required the development of detailed safety procedures and a requirement to modify the remediation design as new results were obtained. An initial challenge was to mitigate a near vertical, 90 m headscarp with localized, blast-induced slope failures. Back-analyses with numerical modeling software indicated that the failure surface could be shallower, which contradicted the initial failure interpretations. Eventually, drilling results confirmed this alternative failure geometry. The final remediation design incorporated shallower slope geometries and an approximately 3 Mt buttress along the base of the Carlin Formation and bedrock contact to reinforce the subunits with residual strength properties. The results are a stable highwall within the Carlin Formation following nearly 10 years of repeated slope failures, and an example of the necessity to conduct appropriate geotechnical and hydrogeological studies during the early stages of a new layback evaluation or new openpit development.

By A. Rai

"This paper provides an overview of the current use of auxiliary ventilation product and the challenges with limited air quantity in dead-end entry or working face. The PVC low frictional factor, low physical constraint and minimum leakage ventilation duct was development with ""made in US and used in US"". The PVC duct development covering operational and total cost of ownership with on-going success will be presented. This paper will discuss mine sites using new PVC vent duct underground and the results from operational and technical side making a difference. INTRODUCTION The Turquoise Ridge Joint Venture (TRJV) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestone’s, siltstones, and mudstones. The weak nature of the ground facilitates the underhand cut and fill mining methods [3].Mining Method; Underhand cut and fill : The mine uses underhand cut and fill method which has 12’x12’ top cuts and several different size undercuts. The ore body is accessed off of a secondary development heading, utilizing a heading with a cross section of 14W x 14H or 15W x 16H configuration. In the wider and more massive zones, two headings in a production panel may be worked at any one time. Drift round lengths are determined by the type of drilling machine being used. An example of a typical topcut and associated undercut layout is shown in Figure 2. SECONDARY / AUXILIARY VENTILATION IN UNUNDERGROUND METAL MINES The auxiliary ventilation system provides the required air volumes at the face of dead-end developments and production workings, which in many cases may be considered as the primary method of assuring that the air quantity and quality standards in these working areas are satisfied. The Auxiliary fans and ducting systems are usually the primary means of delivering the required air volumes to the face of dead-end developments and production workings. Both centrifugal and axial-flow fans are used in underground auxiliary ventilation systems, usually electric powered. The internally direct driven axial-flow fans tend to be more popular because of their compactness and adaptability to staging. The most commonly used materials for ridged tubing are coated steel, alloyed steel, fiberglass and resin. Flexible (collapsible) ventilation tubing is also used and is usually made from neoprene-coated or nylon material. To add stiffness and reduce collapsibility these fabric ducts can be formed over a steel spring frame. A very important factor in the design of an auxiliary ventilation system is to minimize leakage and reduce the frictional pressure losses along the auxiliary ducting systems by minimizing their friction factors (K)."

Jan 1, 2015

By L. R. Shotwell, C. F. Voss, R. J. Bastian

Pacific Northwest Laboratory (PNL) currently supports the U.S. Department of Energy's Office of Civilian Radioactive Waste Management in developing and evaluating analytical methods for assessing the suitability of sites for geologic disposal of high-level radioactive waste. The research includes consideration of hydrological, geomechanical , geochemical , and waste package components and the evaluation of the degree of coupling that can occur between two or more of these components. The PNL effort and those of other research groups investing potential waste sites in the U.S. and abroad are producing a suite of computer codes to analyze the long-term performace of the proposed repository sites. This paper summarizes the ongoing research in rock mechanics at PNL involving flow through jointed rock. The objective of this research is to develop a methodology for modeling the coupled mechanical-hydrological process of flow through joints and then attempt to validate a "simple" model using small -scale laboratory test data as a basis for judging whether the approach has merit. This paper discusses the laboratory tests being conducted to develop s joint behavioral constitutive model for the numerical method under development and the modeling approach being considered.

Jan 1, 1986

By C. M. Brown

The semi-autogenous grinding circuit at the Utah Mines Limited, Island Copper Operation, located on Vancouver Island, British Columbia, is described. Since start-up of the operation in 1971 grinding circuit throughput has been progressively increased from the initial design rate of 30,000 to the current average 45,000 tonnes per day (t/d) of porphyry copper ore. Key developments and modifications in operating and maintenance practice that have contributed to this increase are reviewed.

Jan 1, 1985

By Carter Brown, Kate Brown Requist, Eric Lutz, Moe Momayez, Athira Satheesh

New mining health and safety training modalities are becoming increasingly prevalent in the underground mining industry. Various digital training tools have been developed over the past several years, but the extent of their use remains unclear. Advances in gamified training by way of computerbased video games and virtual reality (VR) have opened a new avenue for mine rescue and self-escape training, but these methods have not been widely adopted across the mining industry. Mine rescue and self-escape situations require a mix of in-classroom training as well as live drills, but it is important to assess the extent of and effectiveness of new training modalities. The Mine Rescue and Self-Escape Survey (MRSES) was distributed to underground mining operations to collect perceptions of current training effectiveness as well as willingness to adopt new training methods as a complement to live rescue drills. Responses from the MRSES indicate that adoption of digital training technologies has been slow-going despite an interest in their use. Further, there appears to be no meaningful connection between more frequent escape and rescue training and feelings of emergency preparedness. With relatively little use of already developed digital training tools but an interest in their adoption, it may be time to reassess current emergency preparedness training philosophies.

May 1, 2025

By N. E. Norman

The big hole drilling industry is a relatively new one. In fact, very little big hole drilling was done prior to 1950. If there is to be a marriage between big hole drilling and mining, we should certainly take a look at the background of the big hole drilling industry. Let us examine the three main features of big hole drilling and determine how each applies to mining. Let's also look at the good qualities and the limitations of each of these character traits.

Jan 1, 1968

By Richard V. Good, John B. Harvey, Lloyd S. Jones

INTRODUCTION The term "Rapid Underground Excavation" is generally associated with high speed tunnel advance with large volumes of excavation, and indeed this is the type of work for which most of the recent innovations in methods and new machinery have been developed. However, the term applies as well to any underground excavation process that results in an earlier project completion than would be expected with conventional methods, and hopefully with a decrease in total unit excavation cost. Often significant progress has been made during the primary stages of an underground construction project and then an inordinate amount of time and effort has been expended on small units of "miscellaneous" excavation which has delayed the overall project completion and escallated overall unit costs. Construction at the Nevada Test Site of the Atomic Energy Commission for underground testing frequently requires significant amounts of so called "miscellaneous mining" such as short access drifts, cross cuts, alcoves, niches and concrete keyways. Many of the keyways must be excavated without disturbing the rock beyond the excavation lines and construction scheduling often dictates that much of the work must be accomplished without disturbing sensitive electronic equipment already installed. In order to cut down on lengthy and costly delays required for the tedious manual excavation of much of this miscellaneous mining, a market search was made for suitable mechanical excavation equip-

Jan 1, 1997

By A. G. Kim

Increasing transportation costs, clean air regulations and the decreasing availability of landfill space are factors in the increased interest in the utilization of low cost disposal sites for coal combustion residues (CCR). Inactive surface and underground coal mines can satisfy the conditions for stable CCR disposal sites, and subsurface CCR injection can be beneficial in reducing the amount of acid mine drainage (AMD) often produced at such sites. The material is expected to add alkalinity to the subsurface environment and to decrease the permeability and porosity of the buried spoil. Both mechanisms can reduce the amount of acid normally generated at a mine site. The Bureau of Mines is cooperating with an independent coal company in a test of subsurface injection of a mixture of fly ash, from conventional power plants or from fluidized bed combustion (FBC) , with AMD sludge into a reclaimed surface mine. Changes in water quality parameters and the concentration of heavy metals in water samples from wells and seeps are being used to assess the effect of CCR injection. The preliminary results discussed here indicate that improvement in subsurface water quality was related to fly ash injection and that components of the fly ash were stable in the acid environment.

Jan 1, 1994

By Patrick McElhinney, Jacob Carr, Bruce Whisner, Cory DeGennaro, Jingcheng Li

Since 2016, electromagnetic interference (EMI) of personal dust monitors (PDMs) with magnetic proximity detection systems (PDSs) has been observed in underground coal mines. The EMI causes the magnetic field measurements of a PDS to change, which, in turn, alters the calculated location of the miner relative to the machine. Any altered location calculation can potentially cause the PDS to fail to warn a worker who is at an unsafe distance from the machine, arousing a serious concern on safety hazard caused by EMI in underground mines. The search for EMI mitigation strategies led to the development and use of large shielding pouches and boxes to hold the entire PDM to reduce its magnetic emission. Research on these pouches and boxes found that although they were able to reduce the emitted radiation from the PDM, they also disturbed the magnetic field of the PDS, affecting its performance. Researchers from the National Institute for Occupational Safety and Health (NIOSH) have focused on shielding internal PDM components rather than shielding the entire PDM. The PDM air pump motor is one of the PDM components that has been identified as a major source of electromagnetic radiation and has been selected for further study and tests. The measurements show that a small copper or aluminum foil enclosure can effectively reduce the magnetic emission of the motor by between 50 and 85% at 73 kHz. This study compares the test results of the air pump motor with various cost-effective shielding materials. The data provided in this paper can serve as a reference for shielding enclosure design of the PDM air pump motor to reduce its electromagnetic emission as one form of EMI mitigation strategy.

Microorganisms have been widely used for hydrometallurgical operation and effluent treatments(Smith, et. al., 1991a; Gadd, et. al., 1986; Darnall, 1986; Paponettis, et. al., 1991; Mihaylov, et. al., 1991; Rusin, et. al., 1991; Noble, et. al., 1991; Yang, et. al., 1991). In recent years there is a growing interest in using microorganism for flocculation of minerals fines and flotation collector (Smith, et. al., 1991b, 1991c; Misra, et. al., 1991a, 1991b, 1992a, 1992b). It is envisioned that the utilization of nonpathogenic microorganism and/or extracellular surfactant derived from microorganism as a flotation collector will replace some of the environmentally toxic flotation collectors and at the sometime improve flotation efficiency. The selection screening, and judicious selection of appropriate microorganism as flotation collector has been a challenge to process engineers. Over the past five years, continued research at the University of Nevada has shown that certain microorganism Mycobacterium phlei (M. phlei) can be a good flocculating agent and has potential to be used as a flotation collector (Dubel, et. al., 1992; Misra, et. al., 1991a, 1991b, 1992a, 1992b; Smith, et. al., 1991d; Chen, et. al., 1992a, 1992b)).

Jan 1, 1993

By Odin Wilhelmy

Agriculture in the United States today is becoming more and more a business, rather than a way of life. In the light of this, it behooves the farm-supply industries that provide the American farmer with his tools of production--feed, fertilizer, machinery, and the like--to give even greater attention than they have in the past to meeting the needs of the farmer-businessmen they are serving. Increasing competition among the companies that make up these industries merely accentuates this need for better service. An opportunity for such improved service, not yet fully realized, exists in the fertilizer industry today. That opportunity lies in the increased transportation of fertilizer ingredients by water. However, before the benefits inherent in this increased water movement of fertilizers can be fully realized, certain obstacles must be met and overcome. It is the purpose of this paper to outline the nature and magnitude of this opportunity, to point out some of the roadblocks and the steps that can be, or are being, taken to remove them, and to indicate some of the rewards that would logically stem from success in these efforts.

Jan 1, 1961

The Kinross DeLamar Mine has been operated for more than 17 years producing precious metals dore' from ores, principally silver bearing with associated gold co-products. In late 1995 a new orebody was commissioned, the Stone Cabin orebody, and the site began a phased shift from silver dominance to gold dominance in terms of precious metals revenue. The Knelson Concentrator was selected to remove gold from a portion of the cyclone underflow stream in the grinding circuit. This paper describes the development of the flow sheet, specific mineralogical impacts on Knelson product and downstream materials, and impacts on mine/mill grade reconciliation.

Jan 1, 1997

By W. R. Dengler

In Canada, most of the rock being broken in underground metal mines is being done by using traditional drilling and blasting methods. Despite advances being made in hardrock boring and other, more exotic techniques, Dynatec believes that the traditional methods will prevail for many years. It is also believed that modest research efforts expended on the traditional methods will result in substantial financial benefits to the mining and rock tunneling businesses. Dynatec has pursued productivity improvements through the use of long rounds in shaft sinking and lateral development. The concept of longer rounds was developed by Dynatec on the Craig Shaft Sinking Project (RETC, 1991). This technology was subsequently used to sink the two shafts at Aur Resources with great success. The development of a Long Round Jumbo for tunneling is a natural progression of the long round technology developed for the Craig Shaft. The Dynatec Long Round System has been patented in the United States and South Africa, with additional patent applications pending in Canada and Australia.

Jan 1, 1993