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By Rudolf E. Greuer

This study concerns itself with two topics of the mine ventilation - mine fire interface which, when the work for this study began, did not seem to receive sufficient attention. Section 1: Comments on Spontaneous Combustion of Coal in Mines It is attempted to describe heat generation, heat and oxygen transport, in such a way that existing experimental data for U.S. coals can be used to assess conditions inducive to spontaneous heatings quantitatively. Investigated are, in particular, critical air velocities, minimum sizes of coal accumulations, moisture contents and the influence of mining factors. An extensive, practice oriented literature survey is included. Section 2: The Early Detection of Mine Fires by Assessment. of Mine Gases The suitability of the major constituents of combustion products for an early detection of fires is discussed. The same is done for gas concentration ratios. Since it was felt (at least at the time when this report section was written) that the value of the carbon monoxide/oxygen deficiency ratio was overestimated, the usefulness of monitoring this ratio as compared to monitoring CO concentrations was critically investigated. The state of art concerning instrumentation and organization of fire detection systems is reviewed also.

Jan 1, 2011

By Turgut Yalcin

"Recent years have seen a resurgence of interest in flotation cell design, and one of the areas where attention is being focused is flotation in centrifugal fields which aims at increasing the flotation rates by forced bubble-particle contact.A new cycloflotation device was developed at Laurentian University and tested on the nickel ore of Falconbridge Limited in Sudbury. In comparison with conventional flotation, cycloflotation yielded at least seven times faster flotation rates in terms of the mass of solids floated per unit time per unit flotation volume, while producing concentrate grades similar to those of conventional flotation. These results, which were obtained with a bench-scale ""cyclofloat cell,"" suggest that cycloflotation has the potential of setting a new direction in flotation technology.IntroductionFroth flotation is no doubt the dominant separation technique in the mineral processing industry. Since its inception early in this century, much research effort has been and is still being expended on this process. Until recent years, emphasis seems to have been placed on the chemical aspects of flotation, but there is now an increased awareness for the need to improve flotation machine performance and more and more attention is being directed towards this area. In a 1982 article on ""Flotation Machines"" (Young 1982) it is stated that "" ... by now the design of the machines used would have reached a high level of perfection, ... In fact, this is not the case ... "".The process of flotation in a flotation device may be considered to take place in several distinct stages as follows:"

Jan 1, 1994

Previous published papers by Fraser (1), Hey (2), and Stillwell (3), have given respectively, details of:-1. The practice in the pilot plant operated at Zeehan for the treatment of ores from the Rosebery field.2. The design, based largely on the experience gained at Zeehan, of the concentrator built at Rosebery.3. The nature of the orebodies of the zinc-lead lode at Rosebery.Changes and developments, at the Rosebery concentrator, since operations commenced, are now described with particular reference to recent practice.Three concentrates are produced, viz.: a copper, a lead, and a zinc concentrate. The current flow-sheet is shown in Fig. 1. Typical concentrate assays are...THE OREThe ore treated is derived from the Rosebery and Hercules Mines and is, milled in the ratio of, approximately, two parts of the former to one of the latter. The ores from the two mines may be considered as being similar in general character, although the Rosebery ore contains more pyrite. It is from this mine that any increased tonnage is expected. The ore is a mass of fine-grained, intimately associated sulphides, with practically no coarse...

Jan 1, 1949

By G. Warren

"In the past, smelting and refining of the precious metals recovered from ore has been generally looked upon as a small and relatively minor component of the business of gold mining. This is not surprising when one considers that the manpower, space and capital components of a gold refinery at an operating mine can be several orders of magnitude smaller than other unit operations at the same location. This philosophy is changing however, as economic and environmental pressure are forcing a re-evaluation of all aspects of gold mining and milling.This paper describes and evaluates three furnace technologies available and used by precious metal operators. The operation of arc, induction, and reverberatory furnaces are discussed and their strengths and weaknesses with respect to capital cost, impurity removal, slag quality, and environmental concerns highlighted.INTRODUCTIONIn the past, smelting and refining of precious metals recovered from ore has been generally looked upon as a small and relatively minor component of the business of gold mining. This is not surprising when one considers that the manpower, space, and capital components of a gold refinery at an operating mine can be several orders of magnitude smaller than other unit operations at the same location. Generally, gold producers will spend a great deal of effort to squeeze the last drop of efficiency out of a leach or grinding circuit via simulation or testwork but will design and build the refinery based upon past practices or industry standards. That past practices or industry standards will provide a functional refinery is undisputed; that this philosophy achieves the efficiencies that are possible or demanded in other plant operations is debatable.Environmental and worker hygiene requirements are considerations as well. Pollution control equipment can become a substantial contributor to both the capital and operating costs of a refinery and furnace selection has a marked influence upon the type and cost of this equipment. Slag characteristics and subsequent processing options available also play a role in furnace selection as precious metal slag losses and the recovery effort can greatly influence the cost / benefit analysis of a particular technology."

Jan 1, 2001

By V. F. Parry

[Approximatel~r 7-1/2 illion tOlls of subb1tnminous coals are mined an-nuall in Colorado, Wyo~ing, and Montana, of which 50 percent probably reaches dome ,-tic conswno:os. r:L'he moi s t'_re of the se subbi t1.Uninous coal sis high, averae;:t.:ug about 25 :!,)ercent \-Then they are :nined. T'ne coals are non-caking d ~~ack to a vari ble degree when exposed to nornal atmospheric conditions. ~hey a~e gpod domestic fuels, are considered to be smokeless in most furn~ces, and have been used. f, r f!1an: y ars in hand-fired domestic furnaces in hich tnc practice i~ to e~ploy large lureps for efficient com-]

Jan 1, 1941

The theme of this Conference is 'The Future of Mining in New Zealand' to be addressed at a time of deepening economic concern. To ensure the assessment and development of our mineral resources in a competitive, safe and environmentally acceptable way a modest supply of a rare commodity û the professional mining engineer û must be assured. This paper briefly' reviews the history of mining education in New Zealand, discusses relevant overseas academic concerns and actions and discusses recent local trends which have led to a most serious recruitment position in the Department of Mining Engineering at the University of Auckland. Conclusions are drawn and proposals made which may remedy this situation which could have serious economic and sociological consequences for New Zealand.

Jan 1, 1991

By Enrique Castells

La extracción del mineral es el método más habitual para la explotación minera y se realiza a través de rampas, galerías, y túneles que permitan el acceso hasta la zona de minado. Sin embargo, cuando se da una excesiva profundizaciión del terreno, se emplea el método de pique vertical ya que logra el acceso de los operarios a las zonas más profundas de un modo más rentable y rápido a través de la extracción del mineral por izado de vagones o skip hasta el de nivel de superficie o intermedio. Por ello, es común que las minas replanteen la sustitución de su sistema de extracción habitual por el de izado por piques. En este sentido, el presente trabajo desarrolla la aplicación de los piques verticales en los sondeos de exploracion de la mina Hullera Vasco Leonesa. La primera parte del proyecto describe la ejecución de dos piques verticales (Aurelio y Emilio del Valle), y la segunda, en la ejecución de más de 17.000 m de galerías y obras de infraestructura de diversa índole.

Sep 13, 2001

By Mary Ellen Bruce Large

"In partnership with California Department of Transportation (Caltrans), Federal Highway Administration (FHWA), and with support from International Association of Foundation Drilling (ADSC), Deep Foundations Institute (DFI) organized a workshop on quality assurance (QA) practices for acceptance of post-grouted drilled shafts in conjunction with DFI’s 40th Annual Conference on Deep Foundations. The 1½-day workshop was held on October 15-16, 2015 at the Oakland Marriott City Center in Oakland, CA.Post-grouting, in the context of this workshop and report, refers to the alternative design and construction of base-grouted drilled shafts wherein a grout distribution system is installed during construction and used to grout the base under pressure after the drilled shaft concrete has gained adequate strength, resulting in a stiffer axial-compression load-displacement relationship and additional possible ground improvement effects.The primary goals of the workshop were to•?Identify and summarize the state of the practice for design, construction, inspection, verification, acceptance criteria, reliability and performance of post-grouting.•?Identify gaps and needs in quality assurance that should be addressed for successful use of post-grouting.This report is structured to follow the workshop program: workshop presentations outlined the state of practice and views from owners, engineers and contractors on acceptance of post grouting methods for drilled shafts; and subsequent workshop discussions attended by a small invited group of participants focused on identifying areas of agreement and disagreement on post-grouting best practices, acceptance criteria, design and verification procedures, and inspection requirements. A partial list of attendees of the open and closed sessions is provided as Appendix A, and copies of presentations are included as Appendix B.FHWA and Caltrans are the primary audiences for this report, and its content will be used to develop a roadmap for deploying the findings into policy and practice. The secondary audience is the broader industry group, and the report content will be disseminated in a variety of formats."

Jan 1, 2016

By Mary Ellen Bruce Large

"INTRODUCTIONIn partnership with California Department of Transportation (Caltrans), Federal Highway Administration (FHWA), and with support from International Association of Foundation Drilling (ADSC), Deep Foundations Institute (DFI) organized a workshop on quality assurance (QA) practices for acceptance of post-grouted drilled shafts in conjunction with DFI’s 40th Annual Conference on Deep Foundations. The 1½-day workshop was held on October 15-16, 2015 at the Oakland Marriott City Center in Oakland, CA.Post-grouting, in the context of this workshop and report, refers to the alternative design and construction of base-grouted drilled shafts wherein a grout distribution system is installed during construction and used to grout the base under pressure after the drilled shaft concrete has gained adequate strength, resulting in a stiffer axial-compression load-displacement relationship and additional possible ground improvement effects. The primary goals of the workshop were to•?Identify and summarize the state of the practice for design, construction, inspection, verification, acceptance criteria, reliability and performance of post-grouting.•?Identify gaps and needs in quality assurance that should be addressed for successful use of post-grouting.This report is structured to follow the workshop program: workshop presentations outlined the state of practice and views from owners, engineers and contractors on acceptance of post grouting methods for drilled shafts; and subsequent workshop discussions attended by a small invited group of participants focused on identifying areas of agreement and disagreement on post-grouting best practices, acceptance criteria, design and verification procedures, and inspection requirements. A partial list of attendees of the open and closed sessions is provided as Appendix A, and copies of presentations are included as Appendix B.FHWA and Caltrans are the primary audiences for this report, and its content will be used to develop a roadmap for deploying the findings into policy and practice. The secondary audience is the broader industry group, and the report content will be disseminated in a variety of formats."

Jan 1, 2016

At long last, mining is on the rebound in Minnesota?s Iron Range and the excitement is starting to show. The SME Minnesota Section?s annual meeting was once again held in the heart of Iron Range country, at the Duluth Entertainment and Conference Center on the Duluth waterfront. The conference boasted a record attendance of 475 people and its largest-ever trade show. Appearances by Governor Mark Dayton?s new Iron Range Resources & Rehabilitation Board (IRRRB) appointee, Tony Sertich, as well as a local Fox news crew (see clip on SME website [link: http://fox21online.com/news/duluth-mining-conference-breeds-optimism-tech-innovation]) made clear that a lot of eyes [ ] are on the industry as it dusts itself off from the 2008-2009 recession. While the early years of the 21st century were very good to the Iron Range, the global drop in commodities prices and production left many companies reeling and brought back bad memories of the collapse of the industry in the 1980s. However, two years of solid growth and a rebound to above pre-2008 production levels have let the Minnesota mining industry to relax a little and talk seriously about long-term growth and stability.

Jan 1, 2011

By D A. McCallum

With depth, many gold ores become sulfidic with minerals such as pyrite, pyrrhotite and arsenopyrite becoming prevalent. In addition, many underground gold mines use tailings backfill to bind and store the waste. In these cases, acid mine drainage (AMD) can become an issue. One approach to the control of AMD is desulfurisation whereby the sulfide minerals are removed prior to disposal. Four sulfide tailings samples, representing different ore types and gold and base metal operations, were selected for assessment and testing using simple physical beneficiation techniques. The aim was to determine the extent to which mineral processing methods were suitable for separating sulfides from non-sulfides and for extracting potentially marketable by-products from the tailings. In order to streamline the testing procedure a simple diagnostic separation technique was developed to enable quick screening of bulk sulfide tailings for suitability for reprocessing. The testing procedure involved detailed characterisation and a sequential set of testing regimes based on simple unit processes including water washing, classification, gravity concentration, magnetic separation and bulk flotation. The preliminary test results indicate each unit process can play an important part in producing effective sulfide/non-sulfide separations and in generating useful by-products from the tailings. Potential valuable products identified include coarse, benign silica sands, bulk iron sulfide products rich in pyrite and/or pyrrhotite, high-grade iron products (magnetite) low in silica, low-volume bulk sulfide concentrates and low-grade molybdenite and talc products. The work presented shows how sulfide tailings can be viewed as a resource rather than a waste stream, and identifies a pathway for developing a more sustainable approach to the environmental management of sulfide tailings for the future.

Jan 1, 2007

By Bin Tang, Suping Yao

In the last decade, the copper industry in China has developed rapidly and attracted the world’s attention. The production capacity of refined copper has grown remarkably from 4.578 million tons in 2010 up to 9.029 million tons in 2018, accounting for about 40% of the global refined copper production. And now, China has become the biggest refined copper producer in the world. This paper summarizes the application of modern copper metallurgical technologies such as Outotec flash smelting/converting technology, Cyclone smelting technology, TSL (ISA/Ausmelt) smelting/converting technology, Jinfeng side blown smelting and Baiyin side blown smelting technology, Chifeng side blown smelting and continuous top blown converting technology, SKS bottom blowing technology, Dongying two-step smelting technology, copper electrorefining with high current density, etc. in China’s copper industry, analyzes and compares the characteristics of those technologies and presents the great efforts of China’s copper smelters in adapting to the increasingly strict emission standards and improving economic benefits of copper smelters. INTRODUCTION China has been the biggest refined copper producer in the world for many years. China produced million tons of refined copper in 2018, accounting for 40% of the copper smelting production in the world, and of which, roughly, 70% of the copper concentrate was imported, mainly from Chile, Peru and Australia. ICSG (International Copper Study Group, 2017) shows clearly the position of top 20 countries of copper production and copper mine production (Figures 1 and 2). Blast Furnaces, Reverb Furnaces and Electric Furnaces dominated China Copper Smelting for quite long time till 1980s. The first modern copper smelting technology (flash copper smelting) was introduced into China in 1980s, then followed by Noranda, Ausmelt and ISA. Since then, China copper smelting technology stepped into modern time. Since 2000, old processes (Blast Furnace, Reverb Furnaces and Electric Furnaces) were phased out and replaced by modern smelting technologies. China Copper Production has been increasing dramatically (Figure 3).

Jan 1, 2019

By G. R. Moulder

A device was developed that measures dynamic stress (ultrasonic energy) transfer through installed rock bolts, a measure that is directly proportional to the degree of grout bonding of the bolt to the mine roof structure and thus the ability of the bolt to bear static stress. The rock bolt bond tester (RBBT) is a hand-held portable device that shows three ranges of bolt bond condition; i.e., one-third (Bad bond), two-thirds (marginal), or fully bonded. These are shown respectively by a red, yellow, or green light that displays for 4 s. RBBT performance was verified with 2 1/2-to 8-ft bolts installed in various types 0f mine roof structures (sands tone, shale, and boney coal-mud), and 15 now being tested by the Bureau of Mines in mines across the United States. The unit is about the size of a five-battery flashlight and contains the transducer electronics, and battery pack. The RBBT is designed for extreme ease of operation, requiring only manual contact with the bolt and signal read-out. The batteries are rechargeable and the package is designed for durability in a mine environment.

Jan 1, 1983

By David Allen

Cable bolting is a relatively new strata reinforcement technique that has been used successfully in Australia and the United Kingdom. Jim Walter Resources, Inc. has examined the principles and can visualize its useful application in many areas, such as: a) Longwall pull-out areas, b) Roadway junctions, particularly those involving yield pillars, c) Rib reinforcement, and d) Possible replacement of cribbing in roadways, especially longwall tailgates. This paper describes the conditions which led to cable bolt testing, the results of tests conducted to date, and conclusions about the direction that Jim Walter Resources, Inc. is heading as far as testing and potential applications are concerned.

Jan 1, 1994

By T. Belem

The main objective of this study is to better understand the effect of underground CPB placement conditions on its microstructural, hydro-mechanical and geochemical properties. To reach this objective, three PVC columns, each 3 m high, were built, and were filled with CPB material. The columns allow simulating undrained (UD), half-drained (HD) and fully-drained (FD) conditions along with the measurement of resulting self-weight consolidation settlement of the CPB. Bleed and drainage waters were also collected from each column for geochemical analyses (pH, Eh, EC, SO42- content). After 90-days of curing time, a total of sixty CPB samples were cored from the backfill columns and subjected to uniaxial compression tests followed by physical characterization (Gs, void ratio, water content, degree of saturation, specific surface area). The results showed that the total drainage water and the maximum observed settlement occur mainly within the first 72 hours after the columns are filled. The corresponding volumetric strains suggest that in situ backfilled stopes simulated behave in a similar way to the fully-drained (FD) or the half-drained (HD) conditions. The MIP test results show that the pore structure varies between the top and the bottom of each column.

May 1, 2007

By Arthur E. Morris

Process modeling software is used extensively in process engineering, but there is a notable lack of affordable software for educational uses. This paper describes two educationally oriented software programs for thermochemical modeling of processes involving metals, minerals, and ceramic materials. Both programs run as Excel@ spreadsheet files. The first is FREED, a thermodynamic database program containing datafiles for 2500 species. It contains the entire U. S. Bureau of Mines and most of the U. S. Geological Survey database, plus data for scores of other species drawn from various sources. Several modules are available for manipulating and viewing the data. The second program is THERBAL, for making thermodynamic calculations using FREED data. Equilibrium calculations can be made for systems with non-ideal solutions, for a specified set of pressure, temperature, and input amounts of reactants. An optional heat balance is also calculated. The results are displayed as tables or charts in Excel worksheets. Examples of the use of THERBAL will be given for the reforming of natural gas for DRI production, DRI production, and EAF steelmaking. Some observations will be made on its use in the classroom. The development of FREED and THERBAL was initially carried out at the Department of Metallurgical Engineering, University of Missouri - Rolla as part of a project to preserve and enhance the Bureau of Mines database. The current versions were developed privately by the authors.

Jan 1, 2002

By V L. Los, G J. Abramson

The paper examines three types of polar zoning of ore-forming and associated elements that can be detected from geochemical data. Polar zoning is mapped in the form of geochemical ore systems of various ranks. Various types of polar zoning can be found in some systems, which present a general geochemical model of the ore object. The genetic basis of zoning is examined from the perspective of the conception of geoelectrochemical redistribution of matter, including ore-forming elements. The volume of the geochemical ore system may be used in the prognosis of resources for every rank.

Jan 1, 1999

By A. R. Kiani-Rashid

In this paper, the effect of aluminum content on the formation mechanism, volume fraction, morphology and particle size distribution of graphite has been investigated. Addition of aluminum on ductile iron causes some fundamental changes in iron-carbon phase-diagram and as a result, improves the graphite formation during eutectic transformation. The results reveals that aluminum compounds have been formed in the core of graphite nodules, thus aluminum plays an important role in the formation of graphite nodules. Furthermore, it is indicated that an increase in the aluminum content also leads to an increase in the number of graphite nodules and a decrease in the nodules size. By using EPMA, the segregation of aluminum and silicon between graphite nodules has been studied

Jan 1, 2010

By D. G. Hulbert, J. H. Schubert, R. G. D. Henning

"Froth depth, along with reagent addition and aeration rate, is one of the crucial factors that can be used to control a flotation circuit. Sub-optimal setpoints and disruptions in levels have a severe adverse influence on grades and recoveries. A novel control strategy has been developed which provides exceptionally tight regulation of pulp levels. The controller observes and acts on all the flotation levels simultaneously. This provides a clear improvement over the standard approach, which is to use a set of Pl controllers. The system has been run on several industrial plants and has resulted in reduced fluctuations in level; fast responses to setpoint changes, and fast settling times after start-ups or disturbances. Testwork has shown that the improvements in level stabilisation translate into improvements in recovery and grades.IntroductionProcess control and optimization have an important influence on the economic efficiency of flotation plants. Inefficient operation can allow the wrong balance between grades and recoveries, and can also lead to adverse shifts in the grade-recovery relationship. Of all metallurgical operations, flotation loses the largest proportion of valuable material. Better operation can reduce these losses.An essential requirement of a good controller is that it should be able to stabilize and regulate the plant. Stable operation allows the performance of the plant to be observed without being obscured by the effects of disturbances and fluctuations. The optimum conditions can then be detected more easily. Good regulation can maintain operation at the optimum with proper neutralization of disturbances. Only when good stabilization and regulation are achieved can an optimizing strategy be properly applied.Froth depth, aeration rate and reagent addition are the three means by which a flotation plant is generally controlled. These control actions are effective on different time scales. Reagent addition is slower in its effect as some conditioning time is required. Since reagents are only added at the head of the circuit and at a few selected points within the banks, time is required for the effect of reagent changes to move through the circuit. Because of this slower time constant, reagent addition is more suited to process optimization and to dealing with slower changes in the process. An example of these slower changes is variation in the feed."

Jan 1, 1995

By H Zhou, T Honeyands, M Zhou

In iron ore sintering, packing the granules onto the sintering strand to form a porous bed with optimum permeability is a complex dynamic process. The packed bed voidage is the key factor determining the flame front speed and the final sinter productivity and quality. Previous studies have found that granules are soft quasi-particles with a typical structure of nuclei with an adhering fines layer. The deformation of the adhering layer greatly affects the bed voidage during packing, which is related to the strength of the adhering layer and the force exerted on the granules. In this study, tablets simulating the particle size distribution in the adhering layer of granules were made for four single ore blends. Both the tensile strength and shear strength properties of these tablets were investigated as a function of water content by the uniaxial compression test and direct shear test respectively. The results of compression tests show that the adhering layer becomes weaker and more compliant with the increase of moisture. The most porous ore has a more rigid adhering layer than the other three tested iron ores at any given moisture content. In direct shear tests, the internal friction angle of the adhering layer ranged from 31° to 37° and varied little with the moisture content or ore type. The cohesion constant is around 1 kPa and is quite small compared to the stress applied to the granules during packing. Combined with the results of granulation and packing experiments, the influence of the adhering fines layer deformation on the degree of voidage loss is specifically discussed.CITATION:Zhou, M, Zhou, H and Honeyands, T, 2017. Tensile strength and shear strength properties of the adhering layer of granules in iron ore sintering, in Proceedings Iron Ore 2017, pp 117–112 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017