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By J. T. Clancey

The potential inadequacy of natural gas reserves to supply projected requirements in the 1980's has been pointed out.(1,2) As a result, interest has arisen in the development of new, potentially low-cost processes for the conversion of coal into high BTU gas. In June, 1964, the office of Coal Research (U. S. Department of interior) and Consolidation Coal Company (now a subsidiary of Continental Oil Company) entered into a contract to continue work on coal gasification utilizing the Consol CO2 Acceptor Process. Work under this contract has been specifically directed toward the use of lignite as the carbonaceous feed, although the process is also applicable to non-caking subbituminous coals. The primary objective of this work was to establish the technical feasibility in continuous bench-scale equipment, of the novel features of the C02 Acceptor Process. Secondary objectives were the testing of commercially obtainable acceptors and the design and economic evaluation of a commercial facility. The bench-scale process development has been completed successfully and the construction of a large pilot plant at Rapid City, South Dakota, has been authorized. It is the purpose of this paper to review the technology of this new gasification process and to present the current projected economics of a plant producing 250 MM SCFD of pipeline quality gas.

Jan 1, 1969

By Steve Kral

When discussing stock market investments, a company's performance is important. But so is the financial community's perception of that performance. To be sure, a good product or service, coupled with sound manage¬ment, remains important but is no longer enough. How stock analysts view a company's performance has become equally important. A major task of a mining company's investor relations officer, then, is to build and maintain a positive perception of the company to mining analysts throughout the world. That's a tough assignment in any market. The subject here, though, is gold. And, with its weakened price, gold companies must work harder to convince analysts their company is still a good investment. The analyst, on the other hand, must see through the corporate hype and decide whether it's worth recommending to clients as an investment. No simple task, either. Annual reports, 10-K forms, and quarterly reports only tell part of the mining company's story. Site visits, complete with discussions (sometimes interrogations) with a mine's principals, oftentimes tell an analyst more about a company's investment potential than the annual or quarterly report. So it was that three of the nation's major gold companies arranged a three-day tour of their gold operations in Nevada for a group of 22 analysts and a pair of mining industry scribes. The analysts represented investment houses the US, Canada, and England. The host companies and mines visited included FMC Gold's Paradise Peak mine, Amax Gold's Sleeper and Wind Mountain mines, and Battle Mountain Gold's Surprise and Fortitude mines.

Jan 1, 1989

By W. R. Reed, J. P. Rider

"The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) recently developed a series of models using computational fluid dynamics (CFD) to study airflows and respirable dust distribution associated with a mediumsized surface blasthole drill shroud with a dry dust collector system. Previously run experiments conducted in NIOSH’s full-scale drill shroud laboratory were used to validate the models. The setup values in the CFD models were calculated from experimental data obtained from the drill shroud laboratory and measurements of test material particle size. Subsequent simulation results were compared with the experimental data for several test scenarios, including 0.14 m3/s (300 cfm) and 0.24 m3/s (500 cfm) bailing airflow with 2:1, 3:1 and 4:1 dust collector-tobailing airflow ratios. For the 2:1 and 3:1 ratios, the calculated dust concentrations from the CFD models were within the 95 percent confidence intervals of the experimental data. This paper describes the methodology used to develop the CFD models, to calculate the model input and to validate the models based on the experimental data. Problem regions were identified and revealed by the study. The simulation results could be used for future development of dust control methods for a surface mine blasthole drill shroud. IntroductionIn surface mines, production drilling is an essential process in blasting to fracture the hard rock overburden for removal. During the process, considerable amounts of respirable dust are produced. Past sampling at the shroud area of blasthole drills had documented time-weighted-average respirable dust concentrations ranging from 8.68 to 95.15 mg/m3 (Organiscak and Page, 1995) and 1.04 to 52.30 mg/m3 (Listak and Reed, 2007). These high dust concentrations, which may contain silica, can lead to respirable dust overexposures for the miners working nearby. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is ultimately fatal.Two basic methods are used to control drilling dust: a wet suppression system or a dry collection system (Cecala et al., 2012). Dry drilling techniques using a dust collection system are preferred in rural mining locations where a constant water supply is not available, and in the case of rotary drilling where water is associated with accelerated bit wear due to bearing degradation and hydrogen embrittlement. In addition, dry drilling eliminates freezing-related issues with water in colder climates. Dry dust collectors are highly effective at removing dust, especially the finer material, as long as they are properly operated and maintained (Listak and Reed, 2007; Organiscak and Page, 2005)."

Nov 1, 2016

By Molood Saeedi, Nima Sadeghi, Eskandar Keshavarz Alamdari

This study showed the kinetics of gold chlorination leaching from an anode slime complex containing copper, silver, barium, selenium, and tellurium. AgCl and BaSO4 control the rate of gold leaching, and the interface transfer and diffusion across the product was selected as the desirable kinetic model. The concentration of hydrochloric acid, chlorine gas flow rate, pulp density, and temperature have been precisely studied. The results showed that temperature and hydrochloric acid have a favorable influence on the leaching rate. However, the chlorine gas flow rate is inactive in the reaction rate. Furthermore, the leaching rate decreased with an increasing pulp density. The leaching process was controlled by the interface transfer and diffusion across the product, and the activation energy was determined to be 13.66 kJ mol–1.

Oct 19, 2021

By John Keefner, Charles Kocsis, Kyle A. Scalise

Geotechnical modeling of mines is crucial for understanding the many factors that can pose potential hazards or limit production opportunities. The process of back analyses for modeling is often used, but in many instances, the back analyses can be cumbersome and time inefficient.While thesemodels and back analyses may be accurate, these types of back analyses may not be ideal to be used at mines and by engineers because the process is so time-consuming. This paper introduces event-based back analyses that utilize prior events to create more accurate models while eliminating large modeling time because the models are back analyzed from previous events. The completed analyses supply a more detailed insight into the potential hazards at Round Mountain, an open pit operation, as well as provide a better understanding of how improper risk analysis results in missed opportunities. The more we understand about mining activities and processes through modeling, the safer and more productive mines will be.

May 24, 2021

By E. A. Córdova

Current methods for scratching a piece of rock to obtain or check the characteristics of its component material can sometimes be expensive and time consuming. Scratching a rock core requires an object with a point that it is capable of sliding along the surface of the rock while recording the response from the rock due to the sliding. With the idea of providing a cost efficient solution for a scratch device, a new generation turntable arm, composed of a cartridge with a diamond stylus and a USB output connection to the computer, was used to record the vibrations from the sliding of the stylus along a rock core surface. The output sound from the stylus was captured with the computer as an audio input signal. The raw sound data was recorded in a standard waveform audio format (wav) file, and post-processed using sound spectrum analyzer software (Spectra-Lab) to capture numerical data such as frequency, amplitude, and noise from the file. The results for frequency, amplitude, and noise were compared and plotted against the scanned surface of the rock core in the search for correlations that might represent specific characteristics of the surface being scratched.

Jan 1, 2010

By Vishwajeet Ahuja, Benoit Jones

"INTRODUCTION Shotcrete lining forms an integral part of conventional tunneling and is widely applied for underground excavations. Early strength gain of the shotcrete is a crucial aspect for ground support and safety of operatives. Strength requirements are dependent on various factors such as lining thickness, ground type, excavation size and tunnel depth. The early strength gain is typically monitored using destructive tests, such as needle penetration, stud driving or coring samples for uniaxial compressive strength testing in the laboratory. Being destructive, these tests cannot be directly performed onto the lining without causing damage that must be repaired, which is a particular problem for permanent linings. For this reason and to avoid the need for operatives to work near to exposed ground and/or fresh shotcrete, these destructive tests are often performed on panels, which are sprayed at the same time as the tunnel lining. All current testing methods are also very local, testing only a small part of the lining or a panel, which may not be representative because the temperature history could be significantly different. Therefore, these tests do not provide an accurate or complete picture of the lining strength gain. New testing methods that are non-destructive and can scan the whole lining remotely would be extremely desirable. This paper describes a new method, using thermal imaging techniques, that achieves these aims. It also discusses the real-time on-site application of the method, providing insight into the experience gained and conclusions derived. Shotcrete Shotcrete used for tunnel linings requires immediate strength development. The strength development is a direct result of the hydration reaction of cementitious materials present in it. A progressive sequence of the hydration reaction changes it from a solid suspension (typically referred to as fresh concrete) to a solid skeleton with a porous network and thereafter, into a solid with predominantly discontinuous pores (Byfors 1980). In the case of shotcrete, early strength is needed to support the self-weight and then continuing early age strength gain is required to begin to support ground loads. These strength requirements, along with other workability needs, are met by careful concrete mix design, the use of admixtures, such as accelerator and superplasticizer (BS EN 934-5 2007), and supplementary cementitious materials, such as silica fume."

Jan 1, 2016

By Jr. Foot

EIMCO Process Equipment Company has introduced the new SmartCell series of conventional flotation cells. The flagship of this new development is the 5000 ft3 cell that is the largest available in industry. This new series of cells includes a cylindrical tank design, a conical draft tube and froth crowder. Optional air control, wash water addition and embedded expert control are available. A discussion of the design parameters, energy efficiency, testing, and commercial plant results are presented.

Jan 1, 1997

By A. W. Wensel

The adsorption behavior of sodium oleate on brucite, Mg (OH)2, has been studied by Fourier transform infrared spectroscopy. Both internal reflection and diffuse reflection (DRIFT) methods were used to characterize the adsorbed oleate on brucite. DRIFT measurements were shown to be quantitative, and an equilibrium adsorption isotherm was obtained. The conformational behavior of the adsorbed oleate was investigated as a function of adsorption density. It was found that at sub-monolayer coverage the alkyl chains of the adsorbed oleate had more ?gauche? character than at multi-layer coverages. Also, DRIFT spectra revealed that the adsorbed species were magnesium dioleate. For internal reflection measurements single crystals of MgO were hydrolyzed to form a thin Mg (OH)2 layer.

Jan 1, 1994

By W. M. Colwell

When it comes to the analysis of gold bearing ore, there are literally dozens of variables that contribute to the final "true value" of a given sample. Initial sample selection, splitting size and method, inherent nugget gold, pulverization method, and analytical method variations are but a few. However, it seems that the inherent nugget gold particle is targeted as the primary reason for intra and inter-laboratory variations in assay. The following study will show that this is not always the case. A series of tests were undertaken for the Aurora Partnership-Aurora Project to solve inter-laboratory variations in the analyses of blasthole cuttings. Initial concern was centered on the probability that free gold occurrence was resulting in erratic results for the mine's cyanide shake assays and outside laboratory fire assays. Comparison of fire assay and cyanide shake assay was sporadically consistent with previously demonstrated extraction percentage for the cyanide method. The goal was to delineate the factors that ensure consistency in analyses; implement, where needed, Good Laboratory Practices; and reestablish acceptable analytical method correlation.

Jan 1, 1993

A parametric study was conducted to establish the optimum operating conditions for the column flotation of fine coal. The parameters examined in this investigation included collector and frother dosages, feed solids content, and the volumetric flow rates of feed slurry, air and wash water. Despite the wide range of conditions studied the experimental data were found to fall along single grade-recovery curves, just below the maximum separation predicted by the release analysis technique. The deviation of the parametric test data from the release curve was attributed to the nonselective entrainment of mineral matter associated with poor froth washing. The operating point on the characteristic recovery-grade curve was found to be primarily determined by feed rate and aeration rate.

Jan 1, 1992

By J. A. Botín

Mining investment decisions are difficult since decision analysis is often based on scarce information. The sources of uncertainty in large mining investment projects are particularly numerous and are present in all evaluation stages. Hence the feasibility decision for projects of this nature will largely depend on how well these sources of uncertainty are managed to achieve bankable risk levels. The risk associated to the construction stages of a mining project is particularly difficult to quantify, mainly because the large number of variables affecting constructive yields, and the complex interactions among constructive resources. This investigation focuses on developing quantitative simulation models and tools to increase the value of a mining project by means of an optimization of the preproduction equipment fleet. The models were validated through their application in the Chuquicamata Underground Mining Project.

Feb 23, 2014

By K. R. Miller

Thunder Basin Coal Company has two mines located in the southern portion of the Powder River Basin. 60-90 km southeast of Gillette, Wyoming. The mines are principally located on federal coal leases acquired in the late-1960's. Development plans for the Black Thunder Mine focused on dragline stripping, but environmental considerations during the mid-1970's made truck-shovel stripping the method of choice when the mine opened in 1976. In 1981, the Coal Creek Mine opened as the first dragline mine in the Gillette area of the Powder River Basin. The regional terrain is flat-lying with occasional clinker-capped hills. The mines are located on the Wasatch and Fort Union Formation contact. The coals are Paleocene in age and the deposits are structurally simple, dipping gently to the west. The seams are thick and are classified as sub-bituminous-C. The Black Thunder Mine, with its 21 m thick seam, is strategically located in the center of the highest heat value mining area of the southern Powder River Basin.

Jan 1, 1993

By A. J. Basu

Geotechnical design plays a key role in mine design. I A proper geotechnical design provides a safe working environment and facilitates efficient mining operation. There are mainly three design approaches I) judgmental, based on observational and experiential facts, 2) empirical, based on empirical design formulae, and 3) analytical, incorporating numerical analysis. Most design applications are based on the design methods one and two as mentioned earlier. However, complexities arise in deep underground mining operations and deep open pit mines. These complexities and difficult geological environment introduce more uncertainties and simple empirical formulae would not be adequate as a design tool. These situations require numerical modelling and analysis of the design problems including interpretation of the results obtained from the analysis. There are several tools available for performing the numerical modelling and analysis. A brief review of the available tools was addressed earlier (Basu and Kuruppu, 1995). The authors selected ANSYS (a general purpose finite element analysis tool) for use in mining geomechanics and geotechnical design. This paper includes several examples demonstrating the applicability of this software in designing structures applicable to mining geomechnics. The authors hope that the design examples will demonstrate the use of the numerical modelling and analysis application in excavation design.

Jan 1, 1996

By Alessandro Boscaro, Daniele Martinelli, Cristina Gabriela Oñate Salazar, Daniele Peila, Carmine Todaro

"The wear phenomenon in TBM machines is not a simple issue, as many parameters are playing an important role on the consumption of the tools during a tunnel excavation. The action of the wear due to the contact with the soil can occur on the excavation tools, on the cutterhead, in the excavating chamber and on the screw conveyor. The test developed at the Laboratory “Tunnelling and Underground Space Center” of the Politecnico di Torino is aimed to reproduce the interaction between the tools and the excavated material, simulating the excavation conditions in terms of soil conditioning and water content. The test, which is not standardized, is studied to evaluate the wear in a global point of view. The present work starts by testing the influence of the use of chemical agents during the conditioning phase on the drop of the wear phenomenon, in terms of metal weight loss. 1. INTRODUCTION The wear phenomenon of the excavation tools used in TBM tunneling machines is playing recently a major role in the design stage of full-section tunnels in both soils and rocks. Concerning EPB excavation technology, the main issue regarding productivity is the wear of its components (Peila et al.,2012), which increases the so called dead time in the whole process. The friction generated between the components and the ground causes the consumption of the tools and other metallic components in contact with the ground, described as primary and secondary wear by Nielsen et al. (2006a). This leads to downtime, with risky and complicated maintenance operations (Peila and Schulkins, 2009), as occurred in recent tunneling works in Liguria (Italy). The study of this argument in granular soils is very delicate, as it encloses not only the properties of the excavation tools, but also the characteristics of the ground to be excavated (hardness, mineralogy composition, shape and dimension of the particles and moisture content). The penetration mechanism is based on the scraping of the ground, by mean of cutting tools, with its consequent consumption. Concerning the rocks, the excavation principle is characterized by crushing the rock mass matrix by applying high compressive stresses through cutting disks. In such a way, to avoid frequent downtimes and their consequent economic losses, it is very important to study this subject and therefore understand and forecast the durability of the components, in order to try to maximize the productivity of the machine by reducing the frequency of maintenance stoppings."

Jan 1, 2016

By Eduardo Velasco, Paz Navarro, Alfonso Navarro, Claudio Cimiotti, Alejandro Sanz, Nick Karlin

The LA Effluent Outfall tunnel is a 7-mile long, 18' internal diameter, secondary treated effluent discharge tunnel currently under construction by Dragados USA for the Los Angeles County Sanitation District No. 2 (LACSD). The purpose of this tunnel is to add redundancy and increased capacity for discharge of secondary treated effluent from the LACSD’s Joint Water Pollution Control Plant, located in Wilmington, California within Southern Los Angeles County. Current discharge from this facility flows through two existing tunnels of 8' and 12' horseshoe profile, constructed in 1937 and 1958, respectively. When the new tunnel is complete, it will add an additional capacity of 670MGD in peak wet weather flow conditions. Geology of the roughly 7 mile long tunnel was divided into six reaches by the contract documents. Tunnel Reaches (TR) 1 to 3, comprising 19,550' will be excavated in alluvial sands of the San Pedro and Lakewood formations, with cover ranging from 45 to 90 feet. In this reach the tunnel intersects the seismically active Palos Verdes fault Zone. TR 4 is a 1,600' transitional zone between alluvium and the rock formations of the Palos Verdes (PV) Hills, comprised mostly of Malaga Mudstone. TR’s 5 and 6 total 15,591', and are within the rock formations of the PV Hills with overburden ranging from 315' to 475'. The primary constituent of the PV Hills is Altamira

Jun 13, 2021

By K. H. McDaniel

Eight Mine Weather Stations (MWS) installed at the Waste Isolation Pilot Plant (WIPP) to monitor the underground ventilation system me helping to simulate real-time ventilation scenarios. Seasonal weather extremes can result in variations of Natural Ventilation Pressure (NVP) which can significantly affect the ventilation system. The eight MWS(s) (which previously collected and stored temperature, barometric pressure and relative humidity data for subsequent NVP calculations) were upgraded to provide continuous real-time data to the site wide Central Monitoring System. This data can now be utilized by the ventilation engineer to create real-time ventilation simulations and trends which assist in the prediction and mitigation of NVP and psychrometric related events.

Jan 1, 1997

By M. Li, J. K. Thompson, A. S. Azman

Powerful mining systems typically generate high-level noise that can damage the hearing ability of miners. Engineering noise controls are the most desirable and effective control for overexposure to noise. However, the effects of these noise controls on the actual hearing status of workers are not easily measured. A tool that can provide guidance in assigning workers to jobs based on the noise levels to which they will be exposed is highly desirable. Therefore, the Pittsburgh Mining Research Division (PMRD) of the U.S. National Institute for Occupational Safety and Health (NIOSH) developed a tool to estimate in a systematic way the hearing loss due to occupational noise exposure and to evaluate the effectiveness of developed engineering controls. This computer program is based on the ISO 1999 standard and can be used to estimate the loss of hearing ability caused by occupational noise exposures. In this paper, the functionalities of this software are discussed and several case studies related to mining machinery are presented to demonstrate the functionalities of this software.

Jan 1, 2016

By Roger C. Wilmoth

The most common method of treating mine drainage to prevent water pollution consists of neutralization and aeration. This process removes the acidity, iron, aluminum, and some other heavy metals, but does not render a water suitable for domestic or industrial use because of the high dissolved solids, hardness, and sulfate in the treated water. The Environmental Protection Agency (EPA), has been sponsoring and conducting research since 1966 on the use of reverse osmosis (R.O.) for the treatment of mine drainage. This process has been found to be highly effective in the removal of nearly all the dissolved solids. In addition, since R.O. is a concentrating process, potentials for recovery of valuable heavy metals are possible. This paper is a review of the state-of-the-art on the treatment of mine drainage by reverse osmosis.

Jan 1, 1972

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"During the last ten years great strides have been made, on the Mesabi Range, in the practice of beneficiating low grade iron ore material. By .beneficiation is meant all methods of removing impurities, and raising the iron content to a point where it can be sold in open market, the principal impurities being silica and moisture. The • general processes to which low grade iron ores are amenable are as follows:1. Thermal(a) Drying ; removes hydroscopic or atmospheric moisture. .(b) Calcining; removes carbon dioxide from iron carbonate, molecular water from hydrated hematites, and atmospheric moisture.Roasting; removes sulphur, carbon dioxide, molecular water and atmospheric moisture.Agglomeration; primarily for the purpose of preparing finely divided material for blast furnace; briquetting and sintering.2. MechanicalScreen sizing; removes rock and sand.Classification; removes sand by means of currents of water of varying velocities.Log washing; removes fine sand.Jigging; removes larger particles of impurities than is possible by log washing. Certain types of jigs remove fine sand.Reciprocating tables; recover fine iron particles from sand discarded by above processes.Magnetic separation; applicable to the commercial separation of the magnetic oxide of iron from gangue material. From a scientific standpoint it is possible to separate certain hematites and limonites from their gangue:(g) Miscellaneous processes; comprise dry concentration, electro-static separation and other processes."

Jan 1, 1920