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By R. Greenwood

The advent of the space age and its promise of interplanetary flight has prompted new ideas for propulsion systems that will allow maximum energy with minimum fuel weight. The use of cesium as the source of energy for such rocket flights has been found desirable. Theoretical efficiency of a rocket fuel is measured in terms of specific impulse, defined as the number of pounds of thrust per pound of propellant consumed per second. Specific impulse is usually expressed in seconds (the number of seconds for which one pound of fuel would produce one pound of thrust) although it is really a measure of total energy, not of power. The most sophisticated chemical fuels have a specific impulse of 300 to 400 sec; liquid hydrogen heated by nuclear reactor has a specific impulse of 1000 to 1200 sec. Specific impulses as high as 20,000 sec, however, are theoretically attainable with the ion rocket, in which free cesium ions are accelerated across a voltage drop and ejected at high velocity.' Characteristics of the system have been sketched by Boden.2 The desirable properties of an ion propellant are: 1) low ionization potential, 2) low boiling point, and 3) high atomic weight. Alkali metals best fulfill these requirements, and Table I indicates the superiority of cesium. The use of heavy complex ions such as UCl3 is ruled out by their instability and other disadvantages.' Despite its enormous superiority in specific impulse, the ion rocket is inherently low-powered, capable of very small acceleration. Application of ion propulsion will be limited to large rockets and spaceships on missions requiring powered flight for weeks or months and employing a separate chemical propulsion system for escape from the earth's atmosphere where power requirements are large but of brief duration. For example, Kraemer and Larson3 considered the case of an unmanned 25,000-lb pay-load placed in a 300-mile orbit by chemical rockets, proceeding thence by ion propulsion to the vicinity of Mars, where it would go into orbit once again. Calculations provide for 8500 lb of cesium for such a voyage. The question of whether such quantities of cesium will be readily available to the space program does not appear to have been considered by geologists and mining engineers. Present Production and Uses Literature on industrial applications of cesium is scanty. The metal is used in scintillation counters, photocells, infra-red detection devices, and as a "getter" in low-voltage vacuum tubes. Production is sporadic and total figures are not published, but the annual consumption is measured in pounds rather than in tons. The few pollucite deposits known, small as they are, can easily supply the present limited demand for gram or pound lots of cesium. Until recently the price of cesium was $2 to $4 per gram, but according to Chemical Engineering, cesium salts are now available at $13 to $27.50 per lb. Geochemical Distribution As a large alkali ion, the cesium ion accompanies potassium in geological processes and tends to be concentrated in the latest crystallizing fractions of potassium minerals in much the same manner as rubidium. Most of the cesium in igneous rocks, therefore, is in the micas and potash feldspars of granites, and especially in granitic pegmatites. The cesium content rises markedly in the micas of the late by-drothermal replacement stage in complex pegmatite~.' Typically, cesium is only 0.5 to 0.01 times as abundant as rubidium in potassium minerals. Rb', with a radius of 1.47 A, is close enough in size to K' (1.33 A) so that rubidium forms no minerals of its own. Cs+ is so large (1.67 A) that only small concentrations can be taken up in potassium minerals; when cesium is present in solution in larger concentration it forms the mineral pollucite, Cs3-Na2A17Si17O48.3H2O, which is known only in pegmatites. In the weathering of igneous rocks, cesium is dissolved, carried to the ocean, and apparently in-

Jan 1, 1961

By Alan R. Grant

Interpretation of presently available geological information indicates that most of the periods of significant metal deposition in the Washington Cascades Range are, at least in part, genetically related to late Cretaceous -Tertiary intrusive episodes. Chemically, the most favorable environment for base metal deposition is high in potassium. Characterizing the advanced stages of these chemical alteration conditions are the silicate mineral assemblages orthoclase and/or secondary biotite. Wall rock alteration includes both deuteric and hydrothermal processes, the intensity of which primarily depends upon the degree of fracturing in the country rock prior to the introduction of secondary material. Broadly speaking, the primary physical controls for the distribution and concentration of sulfides appear to be a series of structural couples involving both northwest (paralleling regional trends) and northeast--striking systems. Meaningful base metal exploration in the Washington Cascades demands a basic understanding of the various geologic factors related to the distribution of the sulfide deposits. Any geologist contemplating Cascade work should be well grounded in the fundamental concepts of petrology and structure.as these constitute two of his most beneficial aids. The acquisition of the detailed data necessary for this understanding may seem a bit academic, yet it has been demonstrated in numerous instances that a fair economic appraisal of a particular property or mining district depends primarily upon the ability of the geologist to recognize the subtle environmental differences which could lead to the discovery of a major ore deposit.

Jan 1, 1971

By J. Seifert, L. Hunter, P. W. Conrad, S. Rosenthal

"The goal of the protocol for reclaiming in-pit tailings ponds to exceed federal and state regulations was to develop a series of steps that can be followed to design, operate, and reclaim a tailings disposal pond that will develop into grazing land with a wetland for open pit sand mines in warm dry climates. By incorporating a wetland into the reclamation design, the post mining land use gives back to both the wildlife as a source of water as well as providing for a diverse range of post mining land use including but not limited to livestock grazing and ranch land use. An example design was completed using this protocol to demonstrate how the protocol can result in in a well-designed, reclaimed tailings disposal pond. BACKGROUND In an industry plagued with decaying historic mine sites, the public’s perception of mining appears to be poor. While modern mines are closely monitored and generally managed by ethical professionals, history still influences how the public perceives the mining industry. From collapsing abandoned underground workings to historic tailings dam failures, the failure to account for the environment in the past seems to affect public perspective on mining today. In a 2013 “Opinion Former Survey,” a survey conducted through interviews with a diverse range of stakeholders in various gold companies, it was noted that the most serious challenges facing the mining industry were environmental concerns and the permitting challenges associated with them (Council). In another article, this time focusing on Australian citizens and their perspectives of the mining industry, it was found that the majority of those surveyed had a big concern over the environmental impacts of mining especially when it comes to water quality and quantity (Scan). The statistics portrayed in these articles illustrate that today’s mining engineers needs to make more of an effort to change the public’s perspective of mining by being more environmentally aware. These engineers should be continuously asking themselves what they could be doing better from an environmental perspective to ensure that history is not repeated and that natural resources are used as efficiently as possible."

Jan 1, 2018

By M. Mikhaylenko

The most common methods of processing of uranium ores is sulfuric or carbonate leaching with conversion of hexavalent uranium to uranyl carbonate or sulfate anionic complexes followed by sorption of the later by strong base anion (SBA) exchange resins. It is known that chloride anion has high affinity for SBA resins so that it depresses sorption of anionic complexes of uranyl. Application of the SBA resins becomes impractical for recovery of uranium when chloride concentration in pregnant leach solution exceeds 3-5 g/l [1-3].

Jan 1, 2012

By Gary W. Krantz

Fibered, portland-cement-based gunite products were applied in the Bureau of Mines Lake Lynn Laboratory Experimental Mine using a variety of pneumatic guns and gunning crews, The demonstrated wet-mix (with silica fume), dry-mix, and surface bonding products were sampled by the Bureau and subjected to a suite of engineering analyses. Gunite flexural and compressive strength, rebound, permeability, porosity, dust loading, shooting rate, crew requirements, and cost factors were evaluated. Steel, fiberglass, or polypropylene fibers were contained in all but two of the gunires tested. Both Bureau and private testing laboratory analyses are provided for some products. Electron probe micro-analysis and X-ray diffraction analysis were performed on the silica fume fraction of the wet-mix gunite to characterize the dust. Aggregate size fraction distribution analyses were performed to provide strength relationships. Results indicate that all of the commercially available fibered-gunite materials tested can provide beneficial sealant, spall prevention, or roof stability control attributes for underground mining environments when applied by an experienced crew using a well-maintained gun, in accordance with product manufacturers' recommendations and when used for the designated purpose.

Jan 1, 1984

By M. Ge

Signal processing is a major challenge for In-Seam Seismic (ISS) technique. Fourier Transform is an important tool for signal processing such as frequency analysis. However, for ISS signal, localized information, especially time-frequency localization is even more important. Wavelet Transform (WT) provides another approach to study the signal as a function of frequency and time. The objective of this paper is to demonstrate the application and advantages of WT to seismic signal analysis. Both transmission and reflection signals from coal mine void detection experiments are analyzed. The results illustrate that WT appears to be a powerful and convenient method for the in-seam seismic signal processing.

Jan 1, 2007

By D. F. Williams

The modelling, simulation, and design of processes for the recovery of gold from solution by absorption on carbon require the combination of a suitable rate expression with a description of the flow conflguration of the system. By the use of a suitable rate expression from the literature, methods are presented for the design of multi-stage countercurrent absorption systems corresponding to the commonly used carbon-in-pulp and carbon-in-column contacting systems. The sensitivity of the recovery to various design parameters is illustrated. These results have important implications in the choice and design of equipment.

Jan 1, 1985

By Kevin J. Ma, John Stankus

"In order to access remote reserve areas, some U.S. coal mines have to maintain aged underground entries for a great distance. However, high humidity, warm temperature, and time dependent deterioration can cause progressive roof deterioration and unexpected roof falls can, pose a great challenge to ground control engineers. With an active belt structure in place and limited space, re-bolting becomes very costly, less effective, and, sometimes, impractical and unfeasible. To gain long-term entry stability and serviceability, operators typically rehabilitate the aged belt entries by installing standing steel set supports. In the last several years, Keystone Mining Services, LLC, (KMS) has assisted many coal mines with their belt entry rehabilitation projects, evaluated the ground condition of various aged belt entries, and designed different standing steel set support systems. This paper presents a case study of a large-scale roof fall that occurred at an aged belt entry in a mine located in an eastern coalfield, analyzes root causes of excessive deformation of square sets that were installed in an adjacent entry, evaluates the adequacy of an existing rehabilitation square set, and develops remedial recommendations for future rehabilitation practice. Based on the case study, the paper outlines design guidelines for rehabilitation steel sets that include field evaluation, engineering considerations, design assumptions, steel structural analysis, and field installation quality control. INTRODUCTION With gradual depletion of shallow coal reserves, some underground coal mines have to maintain long-term entries (belt, track, return airway, etc.) for a great distance in order to access remote coal reserve areas. However, due to high humidity, warm temperature, and aging in the belt entry, roof strata weathering and pillar degradation become more and more severe. Progressive roof deterioration poses a great challenge to ground control engineers. Pillar rib sloughs at certain locations, entry width increases in some areas, immediate roof sags, immediate roof rock falls out between bolts, existing bolts lose functionality due to corrosion, cutters develop deeper in corners, and strata separation develops deeper up into the main roof. As a result, unexpected roof falls occur in a random manner resulting in loss of production, damage of belt structure, and even injuries to underground personnel."

Jan 1, 2017

By Hossaini SMF

After reviewing the various approach es,namely, empirical,analytical.observational and numerical, a logical systematic approach is proposed for the estimation of compressive strength of coal pillars. In this approach first,uniaxial compressive strength of coal in pillars is estimated,taking into account the size effect and the effect of discontinuities. Next,the compressive strength of coal pillars is estimated by determining the stress distribution in the pillar and the Bieniawski strength criterion. The results appear to be compatible to the ones obtained by Wilson's method. The traditional pillar design equations give improper answers for deep workings.

Jan 1, 1991

By R. E. Ray

Compared to conventional fully ducted axial and centrifugal fan systems, jet fans can offer a number of advantages for control of smoke during fire emergencies and dilution of diesel engine exhaust products in vehicular and rail tunnels. The success of jet fan applications is the result of a balance between the temperature de-rating of the fan, buoyancy forces and the installation momentum transfer efficiency. This paper provides a case study of a unique application of vertically-mounted jet fans in ventilation shafts used to provide both emergency ventilation and pollution control for an overbuild created by the construction of a series of commercial high-rise residential buildings over a portion of an existing passenger rail line. A detailed evaluation of a set of shafts for one building is presented, including a discussion of the calculation methods used to estimate the required jet fan capacity and the results of the subsequent numerical analysis using Computational Fluid Dynamics to simulate the performance of the jet fans during train car fire emergencies.

Jan 1, 2009

By W. Kuckshinrichs

Metallic raw material flows are characterized by a complex global network of producers and consumers, as well as by a multitude of ecological, economic and social impacts across national boundaries and on different scales. This leads to the need to develop methodologies, which allow identifying obstacles that prevent metallic raw material flows to contribute to sustainable development. From a scientific point of view CRC 525 (Martens 2003) has developed an holistic indicator set consisting of approximately 80 different indicators. This set is taking into account the multi-dimensional character of sustainable development. Moreover the indicators reflect different system boundaries according to different actor levels and decision contexts. The full indicator set is important in scientific considerations and suitable for scientific awareness creation. However, to fulfil the function of a decision support approach for political and economic decision-makers some modifications are of central concern. At first a reduction of the full indicator set by selection of core indicators enables decision-makers to deal with complex issues of contrary economic and societal protection targets. Secondly, as thresholds of indicators justify societal call for action, they are discussed against its political or scientific origin. The proposed methodology is exemplified by indicator-based studies of the material flow of aluminium.

Jan 1, 2003

By Jinxing Ji

The thiosulfate lixiviant system for leaching of gold has been under extensive investigation for nearly two decades and consists of ammonium thiosulfate, copper and ammonia. There are several challenges with this system. The occurrence of ammonia must be taken into account from a health and hygiene aspect in the workplace, and also from an environmental perspective with significant levels of ammonia and copper in the tailings. Copper accelerates the leaching rate but causes excessive thiosulfate degradation. A new lixiviant system that has been investigated consists only of sodium thiosulfate without copper and ammonia. Gold leaching is carried out in an enclosed reactor with slightly elevated oxygen overpressure and temperature. Extensive leaching experiments were carried out to minimize thiosulfate degradation and polythionate formation while maximizing the gold extraction. For the preg-robbing carbonaceous ore sample tested, gold leaching was essentially complete within six hours and the thiosulfate consumption was lower than in the typical ammoniacal thiosulfate system. The gold thiosulfate complex in the pregnant leach solution was found to be quite stable under ambient conditions. This new leaching system has the advantages of being more environmentally friendly, has a shorter residence time, lower thiosulfate consumption, lower oxygen consumption, and is easier to control.

Jan 1, 2003

By L. Z. Villanueva

An investigation and evaluation has been performed to determine the potential utilization of electron beam irradiation technology for sulfur oxides removal from reduced-S02-strength metallurgical gases from copper smelters. These off-gases, though too weak to be converted to usable, concentrated: sulfuric acid by conventional means, are characterized by SO2 content higher than 2,000 ppm and a complex chemical composition, including high oxygen content and its generation occurring in a cyclical, fluctuating pattern. This work was based on information supplied by principal smelter companies in Chile. A laboratory facility with flow rate of 20 Nm3/h and equipped with an electron accelerator of beam energy 8.00 keV, has been used for testing. Influence on SO2 removal efficiency of operational parameters such as gas temperature, water vapor content, ammonia feed ratio and irradiation dose was established. The main conclusion of this work, from experimental laboratory tests as well as engineering studies, is that the Electron Beam Process (EBDS) is a cost-effective, simple and appropriate chemical process means for emission abatement. EBDS can, on a site-specific basis, adequately augment SO2 removal to upgrade overall abatement as required and in an optimal manner.

Jan 1, 1999

By Dirk Claessens

The term ?cost? is too small when describing the destructive power of safety incidents for mining companies. Breaches in employee or environmental safety are felt way beyond the bottom-line: human life can be taken; ecosystems tarnished; the ire of peoples, media and government inflamed; significant halting of production; and high levels of legal and financial challenges. According to a recent survey of Mining executivesi, ?ensuring workforce safety? was the most important issues identified above any other, with a plurality of 31 percent, reigning above capital projects, product efficiency, and equipment reliability. We accept that safety is a most paramount issue, yet for many reasons we keep approaching the problem the same way we have in the past. We need to stop doing the same things decade over decade and try something new. New innovations are significantly changing the fundamentals of how mining companies explore, excavate, produce, refine and distribute their valuable commodities. Technologies such as visualization, analytics, location awareness, and gaming simulation are making these enterprises smarter. Now, attention turns to an area we?ve long held as integral to our business: safety. By using the same breakthrough technologies that are changing our business, we can now boldly imagine ? and credibly strive for ? a world of zero incidents.

Aug 1, 2013

By Zuoliang Xiu

Experience indicates that rockbolting is the most efficient and cost effective means of supporting gateroads of retreating longwalls. However, gateroads supported solely by rockboltiug currently accounts for less than 16% of the 4500km of annual gatemad drivage in China According to a stated target of the Ministry of Coal Industry, this percentage should be at least 50% by the year 2000. Since the learning stage of the technology which is indicated by low drivage rates and frequent roof falls in rockbolted gateroads must be overcome , strategies for the application of rockbolting to gateroads have become the focus of discussions on this topic. This pap presents the recent development on longwall gateroad rockbolting technology in China The development work has concentrated on understanding the mechanism of rockbolting; establishing new design procedures of bolting parameters fix gateroad support upgrading the consumable; optimizing bolt installation procedures; adopting better roofbolting machines; and developing adequate secondary reinforcement technique. The authors believe that this development work together with the on-going wok in other aspects of gaterosd rockbolting, as discussed in this paper 9 represent the rational strategies for the application of rockbolting technology to a wider range of longwall gateroads in Chinese d mines .

Jan 1, 1997

By O. Tsuge, G. Hoffman

ITmk3®(Iron Technology Mark III) is an innovative new ironmaking technology whereby high quality iron nuggets are produced directly from iron ore fines and coal in a rotary hearthfurnace1). The reaction mechanism has been investigated in detail through fundamental laboratory research2)3), and the ITmk3 process has progressed from the laboratory to commercialization by the success of the pilot plant tests initiated at Midrex’ Technical Center and at the Kakogawa Bench Plant (KBP) located at Kobe Steel Ltd. Kakogawa Steel Works4)5). Pilot operations have demonstrated rapid production of the iron nuggets with complete metal/slag separation at a relatively low operating temperature. The Kakogawa Bench Plant (KBP) in Japan has logged 21 days continuous operation during which high quality iron nuggets were produced directly from fine ore and coal. The operation technology and the engineering data obtained from these pilot tests were instrumental for the scale-up of the ITmk3 process for the Mesabi Nugget Corp. pilot demonstration plant, which is located at Cleveland Cliffs Inc. Northshore Mining iron ore pellet plant in Silver Bay, MN. The ITmk3 process is an ideally suited technology for siting at the iron ore mine, as it allows the economical production of a value-added merchant iron product.

Jan 1, 2003

By Priyanka Dhar, Kurt Aasly, Hanumantha Rao Kota, Hassan Bouzahzah, Maria Thornhill

The interest in investigating the processing characteristics of mineral deposits in Norway has seen an upsurge in the last decade. One of the major areas of interest is a huge copper deposit, operated by NUSSIR ASA located in the Repparfjord Tectonic Window in the caledonides of west Finnmark. This study reports analysis of ore from the deposit for development and modifications in the flotation flowsheet for the NUSSIR ASA copper ore. The mineralogical characterization for the ore sample was achived by optical microscopy and Zeiss automated mineralogy while grinding characteristics were tested using Bond Index tests. The results confirmed the presence of Cu minerals in the form of chalcocite, chalcopyrite and bornite in the samples, which are mainly liberated in the – 105 µm size range. The majority of non-liberated copper sulphides associated with silica and the carbonates varies from 3 to 28 percent in the –250 µm samples . It is also observed that the copper minerals are uniformly distributed in all size ranges. Selective flotation of NUSSIR copper ore was performed in different size fractions with a motive to identify the correct liberation size and thus to obtain a copper concentrate meeting the quality requirements. The flotation experiments are essentially performed in two stages: the rougher and the cleaner stage. Mass balance calculations were performed showing that approximately 88 percent of copper can be obtained at the end of the process. Ultimately, overall circuit copper recoveries ranged between 83.5 to 88.1 % with a concentrate grade of 35 to 48 % Cu.

Jan 1, 2018

By N. Schreithofer

Varying flow regimes, particle populations and consequently different types of bubble-particle interactions characterize the different zones of a flotation cell. The understanding of the role of the different zones of turbulent intensity on the particle-bubble interactions is of primary importance to optimization and scale-up of flotation processes and machinery. In order to study particle-bubble interaction in turbulent flow a completely new approach was taken. A laboratory scale stationary turbulence device was developed and built. The set-up allows the observation of particle-bubble interactions in various turbulence intensities, particle and bubble sizes and surfactant concentrations. The experimental set-up consists of a transparent, specially designed tank in which liquid flows between carefully designed and placed obstacles that create different turbulent flow fields. Bubble-particle aggregates are introduced into this turbulent zone. The behaviour of the aggregates, such as attachment /detachment of particles to/from air bubbles is recorded by a High Speed Imaging (HSI) system (5400 fps). The images are then analysed and the dependence of attachment/detachment process is described as a function of turbulent intensity in different conditions for different surfactant concentrations. This paper introduces this method to study particle-bubble interactions in turbulent flow and correlation to Computational Fluid Dynamics (CFD) simulation. CFD modelling is validated for two and three phase systems; liquid-gas with liquid and solid tracers respectively. The CFD simulations using the RANS k-S turbulence model showed good correlation to the experimental data and the experimental method is a promising tool for investigation of particle-bubble interaction in turbulent flow.

Jan 1, 2014

By J. Rostami, P. P. Nelson, A. Khetwaln

Tunnel boring machines (TBMs) can be considered as the method of choice for tunneling in many projects due to the high level of efficiency and high potential productivity, safety, and applicability in a variety of subsurface conditions. The muck transportation system in a TBM tunneling operation plays a significant role in the process and impacts the overall performance of the machine. This paper introduces a recently developed method of simulating TBM operation through discrete event simulation (DES), which allows for tracking of the various activities, incurred downtimes in the operations, and overall machine utilization. The study presented here compares two different muck transportation systems, conveyor and rail, under similar geological conditions to quantify the impacts of the choice of muck transportation systems on machine utilization. The results show the applicability and extent of redundancy in the use of the two systems relative to machine capabilities and their sensitivity to geological conditions.

Jun 13, 2021

By T Y. Dube

In this paper current net present value (NPV) based mine valuation techniques that take into account market and private risk are discussed and analysed. Potential pitfalls that arise from the application of a portfolio, market or commodity based risk metric to a mining project are identified. An alternative non-simulative framework for quantifying and factoring market and private risk in NPV calculations is proposed and then applied to a hypothetical case study in an attempt to overcome identified pitfalls. Mathematical proof that a static discounted cash flow (DCF) calculation can underestimate or overestimate mine NPV is presented, the conditions for each are outlined and the degree of underestimation defined.CITATION:Dube, T Y, 2012. How the use of market-based risk metrics can undervalue good mining projects and overvalue poor ones, in Proceedings Project Evaluation 2012 , pp 29-34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012