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By M. Grodner

Underground excavations exhibit different hangingwall conditions in response to varying geotechnical and mining situations. These differences need to be quantified so as to accurately determine the effectiveness of the mining and/or support strategies. A useful tool for the quantification of these differences is hangingwall profiling. Two methods of hangingwall profile measurement are described?termed irregular and periodic methods. Several data analysis techniques are reviewed for these methods and the suitable ones are discussed in detail. For irregular data the suitable techniques are the determination of the length, the average of the profile and the average absolute deviation from the mean of the profile. All of these techniques as well as determination of the moving average of the height and examination of the spectral image of the profile can be successfully applied to regular data. The effect of preconditioning on the hangingwall is discussed as an example and it is quantitatively shown that it results in improvements of conditions. The techniques described allow the engineer to quantitatively identify the appropriate support type or mining strategy and thus represent a valuable decision-making tool. It is suggested that these techniques should be employed on a routine basis by the rock engineers on the mines as part of their geotechnical classification, as well as support manufacturers to quantify the effectiveness of various support types.

Jan 1, 2000

A research project was commissioned by the Australian Coal Association Research Program (ACARP) to improve the understanding of tailgate strata mechanics and to provide a more rigorous engineering basis for tailgate support design. A deformation mechanism termed æskew roofÆ was defined which relates the regional influence of differential horizontal strata movement (shear) about longwall extraction to gateroads. Confirmation of the mechanism was achieved by field investigations which included measurement of the shear displacement along weak interfaces. Under geological and mining conditions where the skew roof mechanism operated, strata units were found to move progressively further towards the goaf with height into the roof. 3D numerical modelling was used to assess the major geotechnical factors controlling the mechanism and to determine appropriate support strategies within a æskew roofÆ environment including the role of cables versus standing supports. The skew mechanism is considered relevant to; all roadways in the vicinity of longwall extraction including the faceline itself, chain pillar design, and support design.

Jan 1, 2005

By Raj P. Singh Gaur

Due to high concentration of NaOH in the digested slurry after scheelite digestion, it is diluted to about 4N before filtration to separate sodium tungstate solution from the sludge (residue). However, in practice there may be deviations in the normality of NaOH present in the slurry. There may also be variations in the temperature of the slurry and filtration time. Slight variations in these parameters could cause tungsten losses in the sludge via the back reaction: Ca(OH)2 + Na2WO4? CaWO4 + 2NaOH This paper pertains to the effect of normality, temperature and time on the tungsten losses in the sludge that is separated from ?diluted-scheelite-slurry-in-NaOH? via filtration. Results indicated that tungsten losses in the filtered residue (sludge) were quite significant when the slurry temperature was kept at 70°C or higher. The effect of high temperature was less significant at the slurry normality of 3.6 or higher. Combination of low slurry normality (<3.6) and high temperature (>60°C) resulted into large W-losses in the sludge.

Jan 1, 2006

By William R. Yernberg

The combined 80th Annual Minnesota Section of SME Meeting and 68th Annual University of Minnesota Mining Symposium was held April 17 and 18, 2007, in Duluth, MN. About 350 mining industry professionals attended the conference, including engineers, executives, mining managers and suppliers from the United States, Canada, Australia, Finland and Brazil. This year’s theme was “Consolidation – Growth – Technology.” The 80th Annual Minnesota Section of SME meeting included concurrent technical papers sessions, a keynote session that featured two distinguished speakers and a general managers session in which taconite mine operators provided updates on their operations. The Minnesota Section meeting also offered an SME short course titled “Control the Feed, Control the Mill.” More than 50 individuals at-tended the short course.

Jan 1, 2007

By R. M. Cox

The ground forces generated by a properly installed and tensioned mine roof truss assembly can provide permanent mine roof support, even in severe ground conditions, either by direct suspension of the rock loads within the potential failure zone above the mine opening or indirect reinforcement of the natural rock arch that tends to form within the immediate mine roof. Notable advancements in mine roof truss support systems hardware and design technology have occurred since the introduction of the in situ mine roof truss concept for permanent mine roof support in 1966. The systematic installation of mine roof truss support systems has proven to be a very effective method of mine roof control room and pillar mines under a wide variety of ground conditions, even in areas otherwise considered unmineable because of severe roof control problems. Properly designed mine roof truss systems have also been used for permanent support of mine slopes and haulage tunnels.

Jan 1, 2002

By S. J. Dillingham

As we enter the new century and close out the old, it has become standard procedure for most blasters to complete a blasting log or shot report following a blast. However, how can you be sure these completed blasting logs are worth the paper or electronic space they occupy.3 Is the recorded data accurate and meaningful? Will the blasting logs stand up under investigation? This paper will attempt to define the purpose of a blasting log, illustrate common mistakes, discuss potential problems, and indicate steps that a company or individual blaster can take to improve and protect against costly errors. The end result will be a reminder of the importance of accurate documentation following a blast that must be given the same individual effort as went into the blasting itself. This paper will also attempt to achieve a proactive training resource to improve the use of blasting logs. A completed blasting log is, quite possibly, the only witness to the overall credibility of the work of the responsible blaster. The log may remain perpetually silent, only to end up in a file that is moved progressively with time to various levels of long-term storage. But, will this silent witness be ready to speak out should a concern arise from the blasting ? Will the blasting log communicate with authority and credibility, or will it be ridiculed by investigation and silenced in shame with costly adverse results for the blaster and company? It is not enough to simply complete a blasting log. The information it contains must be accurate enough to stand the test of time and arduous scrutiny. Unfortunately, most blasters and their associated blasting companies do not realize the status of the silent witness until it is too late.

Jan 1, 2000

By John Smyth

Mining through in panel entries and the full face recovery method has been successfully practiced at U.S. Stwl, Mine 50. Suppat of the cut-through entries and recovery room is critical. Traditionally, concrete crib or fly ash cement backfill has been utilized. However, these traditional methods are not feasible at Mine 50 due to the difficulties of the plow face mining through these types of support. Recent development of new cable support systems provides an option for cut-through entry support. Mine 50 and Jennmar Corporation personnel have worked together to design and apply the cable systems in the cut-through entries and full face recovery room to eliminate standing support. To date, a number of full face recovery rooms and cut-through inpanel entries have been successfully mined. The results indicate that the cable systems combined with high capacity shields, have provided sufficient capacity to support the roof. Utilizing the Jennmar Finite Element Analysis (JFEA) computer program (Stankus and Guo, 1996), an analysis of the stress and roof deflection changes as the longwall gradually cut through was conducted. From the finite element analysis data, a supplemental support plan was designed. The history and experiences at Mine 50 are presented. Based on the case experiences and modifications made to the finite element analysis, an improved design criteria for future use has been formulated.

Jan 1, 1998

By Albaniza Alves Tavares

Neste estudo, a influência do tipo de argila como nucleante heterogêneo para o PP foi avaliada. As argilas organofílicas MPH e MPTH, provenientes do Laboratório de físico-química da UAMG/UFCG, e C20A da Southern Clay Products, em teor de 1% em massa, foram misturadas com o polipropileno (PP) compatibilizado com 15% em massa de polipropileno enxertado com anidrido maleico (PP-g-MA), em misturador interno do reômetro de torque Haake visando a obtenção de concentrados que posteriormente foram diluídos com o PP em extrusora. As amostras preparadas foram caracterizadas por medidas de calorimetria exploratória diferencial (DSC) e difratometria de raios-X (DRX). Os resultados obtidos mostraram que embora as três argilas tenham atuado como agente nucleante para o PP a MPH foi a mais eficiente.

Aug 8, 2018

By Stanton L. Tainter

As a part of a wartime program to aid in the development of known ore bodies and in the discovery of hitherto unknown deposits of strategic minerals, the Bureau of Mines investigated the feasibility of diamond-drilling the Christmas copper deposit, in Gila County, Ariz., to increase the reserves of milling ore. Upon recommendation of the examining engineer, drilling was begun in September 1942, from the bottom (770) level of the mine. One month later, in cooperation with the Bureau, the Federal Geological Survey started geologic mapping of the mine workings. Since extensive and costly development would be required, the War Production Board concluded that ore below the bottom level could not be mined at that time because of the wartime shortages of equipment and man-power. In January 1943, drilling was moved to the 300 and 400 levels to locate reserves readily accessible for continued production of fluxing ore. This drilling, which was under the supervision of L. G. Marshall, was completed in January 1944.

Jan 1, 1948

By J. Humphries

With today?s turbulent markets and unprecedented global opportunities, the need to optimize net present value and internal rates of return from capital investments has never been greater. To help address the need, this paper presents an overview of the key processes and strategies for achieving maximum return from capital projects. Best practices discussed address stage gate management for project evaluation, selection, and oversight, project execution efficiency, value improving practices, operational readiness, and operational excellence. The paper also includes a model of key metrics and benchmarking with tips for application. [ ]

Jan 1, 2011

By ?. ?. Zimin, B. A. Kutlin, X. Baddamsuren

"The ore features of Mongolian fluorspar deposits are shown in the paper. The possibilities of the technological of ore processing on the Bor-Undur combine scheme improvement are analyzed there. Some recommendations are done for scheme development: spare output technologies, the usage large-sized ore separation, flotation by columnar flotation cells, leaching and concentrate agglomeration.New evaluation and usage of mineral sources approach was developed for Mongolian fluoride ores. The conception allows using maximally available mineral resources for getting of metallurgical and acid fluoride concentrates while mining and technological processes: mining (as well as quarrying) -storing, blending-crushing, grinding-combined processing methods-metallurgical using preparation It has been established mining and processing technological schemes should include:• spare blasting technologies providing minimum effect on fluorite crystals which follows ore selective excavation;• large-sized ore separation methods resulted in maximum recovery for these operations in respect to metallurgical fluorite concentrates;• grinding and flotation regimes providing high-quality flotation concentrates getting for their usein chemical industry;• fluorite concentrates agglomeration technologies for providing ability of their use in metallurgical and cement industriesThe results of industrial usage of jugging machines, columnar and pneumomechanical flotation machines for fluospar dressing.The technological approaches implementation in “Bor-Undur” plant maintenance within 1993-2002 years leaded to:• change plant status from just flotation one to gravitational-flotation characterized by technological process stages which are traditional for metallurgical industry and plant capacity increase from 400 to 600 thousand tones of treatment ore as well as concentrate production increase from 120 to 150-170 thousand tones including 120-140 thousand tones of acid grade concentrates with 97% CaF2 ."

Jan 1, 2003

By F. Lindroos

A cornerstone in the LKAB Green Pellet concept is to produce pellets with a small footprint in terms of energy con-sumption, CO2 emission and emission of other elements harmful to the environment, like dust, sulphur dioxides, nitrogen oxides, chloride and fluorine. The concept also encompasses our determination to make pellet products that contribute to low environmental impact and low energy consumption in our customer?s processes. The presentation will focus on the pelletizing process. It will describe both how we have attempted to decrease the generation of unwanted components in the process gas, and how we have tested or evaluated equipment for external gas cleaning. We will discuss and give examples from recent and on-going efforts and outline some of the future challenges we see, to meet our own environmental standards and also the tough demands imposed by EU and national legislation, while striving to boost production.

May 1, 2011

By R. Nendick

"IntroductionThe Ancient Egyptians recovered gold from the mud in the bottom of ponds by having teams of maidens sit around the pond dipping goose feathers dipped in grease into the mud. The gold would preferentially stick to the oily surface and was periodically washed off to give a gold concentrate. This was a forerunner of today's flotation processes.In Greek mythology Jason and the Argonauts pursued the Golden Fleece, which was a primitive form of gravity concentrate produced when gold ore slurry was passed over a sheeps fleece. The heavy gold settled and was caught in the fleece, producing a rich concentrate that allowed Jason & Company to perform the first recorded case of highgrading. The process was a forerunner of todays shuiceboxes used in placer mining.From these simple beginnings, gold metallurgy has progressed to a state where very complex flowsheets are proposed, sometimes to perform a simple metallurgical task. Figure (i) shows a hypothetical flowsheet to identify the range of unit processes that might be brought to bear on a refractory ore. The flowsheet identifies the three primary areas of gold metallurgical operations:Ore PreparationExtractionRecovery."

Jan 1, 1986

By S. Underwood

The tracer gas method of conducting ventilation surveys is a means of determining air quantity in underground mines with knowledge of the concentration of the tracer in the atmosphere and the flow rate at which the tracer is being released. The technique is useful in inaccessible areas of underground mines and areas where traditional point measurement of velocity is not practical. Sulfur hexafluoride (SF6) is the industry standard tracer(Kennedy 1987) used in underground mines because it is safe, stable, and not naturally occurring in the mine environment. The implementation of a second tracer will increase the versatility of the tracer gas technique allowing for simultaneous releases for the study of interrelated ventilation circuits, and for conducting multiple experiments in less time. This paper will detail the selection of perfluoromethylcyclohexane (PMCH) as a novel tracer with sensitivity, physical properties, and analysis characteristics similar to SF6. Methods for the release of liquid PMCH into underground mines will be recommended, and the vulnerabilities of sample loss due to condensation of vapor PMCH will be explored. Finally, the benefits and implications of using PMCH as a second tracer will be discussed.

Jan 1, 2012

By Yuemin Zhao, Daniel Tao, Xinxi Zhang, Qingru Chen, Maoming Fan, Zhenfu Luo, Xiuxiang Tao, Guohua Yang

Coal is currently cleaned with the minimum of size reduction, fine particle processing, recovery, and tailings disposal are major problems. Adequate water resources are not always available. For example, two thirds of China&apos;s coal is located in arid areas. Hence, dry separation provides an alternative approach. Of the dry coal separation methods available, air dense-medium fluidized beds have been used to separate 50~6mm coal efficiently. However, excessive bubbling and back mixing of the separated solids in the air-dense media fluidized bed causes the high lower size limit of 6mm for the feed material, this affecting the preparation efficiency. Based on prior study on air-fluidized dense media for 6~50mm coal preparation, this paper presents methods and test results on the fine coal dry classification, static electricity beneficiation of 0~0.5mm coal, and magnetically stabilized fluidized beds for separating 0.5~6mm coal.

Jan 1, 2005

By D. L. Ogonowski, J. O. Marsden

The Candelaria copper-gold mine is located approximately 25 km south and east of Copiapo in Region III, Chile. The original concentrator was designed to treat 28,000 t/d (30,800 stpd) of chalcopyrite-bearing ore through a circuit consisting of a single 11.0 m(36 ft) diameter SAG mill, two ball mills, conventional rougher and scavenger flotation, column cell cleaner flotation, and ceramic disc filtration. The plant was commissioned in August 1994 and quickly reached design capacity and expected levels of metallurgical performance. In May 1996, a decision was made to double the capacity of the concentrator by the addition of a second line of equipment. The expanded facilities were commissioned in October 1997, less than 18 months after the decision to proceed, and well within the budget. The original concentrator facilities were replicated or duplicated as much as possible, however, a number of important equipment changes were made to take advantage of industry developments since the original concentrator was designed. These included the use of Eimco 120 m3 (4,200 ft3) cells for rougher and scavenger flotation and the installation of a Svedala VTM-800Vertimill for regrinding. This paper describes the rationale behind these changes and explores the reasons for the success of the project.

Jan 1, 1999

By L. Bbosa

Paper written on project work carried out in partial fulfilment of BSc (Hons) (Eng) (Mechanical) degree Discrete element methods (DEM) are being used to provide detailed impact histories of the particles in comminution devices, such as mills. To match this immense detail of information, far more informative breakage tests than those that are generally conducted are now required. The split Hopkinson pressure bar apparatus is used in this study, as it allows the calculation of breakage forces and absorbed energies. The geometry of rock particles has been identified as significant, so this project undertook to identify the influence of shape on the breakage pattern of blue stone. Comparisons are then made between the breakage pattern of angular rocks and rounded, milled rocks for single impact fracture and consecutive impact loading at low energy. Results of this experiment indicate that although breakage for both geometries occurs over a similar energy range, rounded particles have the greater probability of fracture because they absorb more of the impact energy for a given loading. Size distributions of progeny show that five pebbles or more are sufficient to predict the distribution of most particles in small energy regimes. Cumulative impact testing shows that considerably more energy is required to break a rock through cumulative damage than through a single impact?this is of considerable importance in the light of the indications from DEM simulations that most breakage in a mill will be from cumulative damage rather than single impact breakage.

Jan 1, 2006

By Gunnar Persson

The borehole pressure/time history of blasting practice is simulated in a twin pendulum apparatus, where the expanding shotfiring gases force two steel slab swingers apart. A pilot installation built at SveDeFo is described. The relevant factors, that govern the use of this test method as a means of classifying explosives with respect to their toxic fume potential, are described.

Jan 1, 1996

By E. C. Westman, F. J. Shreve

This paper presents the design and construction of a multi-channel geophone array that improves tomographic imaging capabilities in both surface and underground mines. Especially important in the design of the array is sensor placement. Three issues related to sensor placement are addressed in this paper: 1) sensor placement in long, horizontal boreholes, 2) development of simple, robust, MSHA-acceptable clamping unit, and 3) orientation of the geophones within the borehole. Improved imaging capabilities will produce energy, environmental, and economic benefits by increasing exploration accuracy and reducing operating costs.

Jan 1, 2002

By Travis Q. Lyday

The other South Pacific islands included in this chapter extend from Papua New Guinea, east of the Indonesian Province of Irian Jaya on the island of New Guinea, to Fiji, straddling the 180° meridian. A number of islands have been omitted from this chapter owing to the fact that their only mineral production remained insignificant to the economy of the respective country or territory. These islands include the French overseas territories of French Polynesia and Wallis and Futuna Islands; the independent states of Kiribati, Tonga, Tuvalu, and Vanuatu; the New Zealand freely associated state of the Cook Islands; and the New Zealand dependency of Niue. The mineral production that did exist in these islands was limited to construction materials such as coral reef limestone, crushed stone, and sand and gravel in minor quantities used solely for domestic consumption. FIJI Fiji, an archipelago in Melanesia consisting of 300 islands ranging from tiny coral atolls, cays, and rugged coral limestone islets to the larger mountainous, volcanic islands of Kadavu, Taveuni, Vanua Levu, and Viti Levu, straddles the 180° meridian about 1,800 kilometers south of the Equator. Fiji has been an independent member of the British Commonwealth of Nations since October 10, 1970.

Jan 1, 1988