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By J. N. Van der Merwe

In the process of pillar extraction, pillars are seldom if ever extracted completely. The pillar remnants, or snooks, play an important role in the extraction process. At the working face, they need to be stable to provide a measure of support in the immediate area. Further back, they have to fail in a controlled manner to prevent undue load build-up on the pillars that have not yet been extracted. The stability condition at the working area is the result of interaction between the stability of the pillar and that of the roof rock. It is shown that the primary mode of roof layer failure is by bending induced tension. Direct tension can be excluded in most practical conditions, and only in exceptional cases will the first failure be in shear mode. Panel spans required to cause the first goaf to be formed, predicted using analytical considerations, are of the same order as has been observed in practice. Once the first goaf has formed, the horizontal stress is reduced and failure will occur at more frequent intervals. It is shown that bending induced tension is the most likely mode of failure in an unjointed roof layer. In roof layers with a high frequency of weak or uncemented jointing, failure can be expected to occur at spans equal to the joint spacing. In this context, failure will occur at the smallest of the spans required to induce tensile roof failure and the joint spacing. A fundamental procedure to evaluate the likely roof layer failure in a stacked beam system is developed. This can to be used to estimate the loading condition on snooks. It is shown that snooks assist in stabilizing the immediate roof beam. The sizes and positions of the snooks relative to the position of the next pillar to be stooped, control the magnitude of the contribution to stability. The further the snook is from the next pillar, and the larger it is, the greater the contribution to the stability of the immediate roof. Under the condition of loading by the immediate, continuous roof beam, the position and size of a single snook controls the load acting on it. The closer it is to the nearest solid, provided that the roof overhang extends beyond the snook, the greater the load on it. However, once the immediate roof beam fails, the loading conditions change. The snook is then loaded by the tributary area load. A procedure is developed to assess the condition of snooks for different situations. Using the fundamental considerations developed in this paper, snooks can be designed to be stable during the active mining phase in their immediate vicinity, but to fail once the next line of pillars has been extracted.

Jan 1, 2005

By Shaun Booth

Automating Delay Reporting to Deliver Effective Maintenance Corporate Background: Technology Company: Matrikon Inc. Global software and service provider of Information Technology and Control Solutions that deliver Business Results. Case Study Facility: Bulga Coal Handling and Preparation Plant <CHPP> Australian site, part of Xstrata, an international Swiss natural resources group. Technology: ProcessMORe ? Missed Opportunity Reporting (Delay Reporting). Matrikon?s technology implemented at many facilities, to deliver effective maintenance Matrikon International Inc. Global software and service provider of Industrial Decision Support, maintenance and control solutions, with universal connectivity to existing systems and work processes. ? 1999 ? 100 employees ? 2003 ? 450 employees ? Our offices: 20 offices worldwide: ? Quebec, Toronto, Edmonton, Calgary, Ft.McMurray, Vancouver ? U.S. ? Australia (formerly Hunter Controls)

May 1, 2003

By T. A. Muhlare

"Large quantities of slag are produced every year and dumped on slag heaps around the world, posing a potential environmental threat due to contained heavy metals content. Slags are waste minerals produced during furnace smelting of minerals. The contained values of base metals may be released into the environment under natural weathering conditions polluting ground and underground water. Copper losses into slag are a continuous problem in pyrometallurgical smelting operations. Due to shortage of ore concentrate, various mining operations have initiated the recovery of copper from dumped slag. The typical process uses crushing, milling and flotation. These operations create excessive liner wear rates during crushing and milling because the bond work index of copper slag is 22 kWh/t and this is considered a very hard slag. The process also has reduced flotation recoveries and requires high flotation reagent consumption. The present work shows that digestion of the milled copper slag slurry with concentrated sulphuric acid at a temperature of 250oC forms a solid cake and leaching of the solid cake with water is a possible option. However, the consumption of sulphuric acid can have a considerable cost on the recovery process. This can be limited by producing a leach residue containing gypsum and silicate materials as amorphous silica which are suitable for use as an additive for Portland cement. Laboratory results show that 90% copper recoveries can be achieved. The leaching is conducted to prevent silica gel formation and iron co-extraction. Leaching is optimum if silica gel-free solutions and good filterable residue are obtained. INTRODUCTION Slag is a waste by-product of smelting and converting operations in metallurgical plants. Both smelting and converting operations are aimed at iron separation from base metal sulphides in non-ferrous metallurgy. The iron sulphide component of the ore or concentrate is oxidized to iron oxide at higher temperatures in the molten form, and then fluxed with silica and other oxide rock minerals to produce fayalite (2FeO•SiO2) slag (Schlesinger et al., 2011). Slags are generally deposited on dumps and considered to be unreactive materials. Smelter copper slag contains significant concentrations of several potentially toxic elements, including arsenic, lead, cadmium, barium, zinc and copper. These elements can be released into the environment under natural weathering conditions and cause pollution of soils, surface waters and groundwater (David, 1998)."

Jan 1, 2015

By F. O. Verret

Several grindability tests were developed over the years to design grinding circuits or optimize existing operations. Each test has its own strengths and weaknesses and it is imperative to select the proper test procedure(s) to meet project deliverables and minimize the risk of a project. Pilot plant testing of large bulk samples historically constituted the traditional approach for AG or SAG design, but was gradually replaced by small-scale tests. Nowadays, conducting grindability tests requiring only a few kilos of material on several samples is a more typical approach to grinding mill design. This paper summarises the requirements and deliverables of various bench-scale test procedures, their strengths and weaknesses, and cases where AG/SAG pilot testing should still be performed.

Jan 1, 2012

By R. A. Bosch, F. V. Lenel, G. S. Ansell

RECENTLY, Ansell and aenel&apos; proposed a dislocation model to account for the yielding behavior of dispersion-strengthened alloys. The criterion for yielding used in this model was that yielding occurs when the shear stress due to arrays of piled-up dislocations fractures or plastically deforms the dispersed second-phase particles. Calculations based on this model predict that the yield strength, uysof a dispersion-strengthened alloy containing particles whose geometry permits them to be considered as straight, i.e. not curved, barriers to dislocations follows the relation where and are the shear moduli of the matrix and dispersed phase respectively, b is the Burger vector of a dislocation in the matrix, A is the mean free path between dispersed phase particles and C is a constant. This yield stress, ys, is closely approximated in polycrystalline alloys by the proportional limit. The offset yield stress, uoy, is the yield stress, uys, plus the increase of stress due to strain hardening in the offset strain increment. Previous investigation1 has shown that Eq. [I] describes the yielding behavior of several different dispersion-strengthened alloys as a function of the mean free path between dispersed phase particles at a constant temperature. The purpose of this investigation was to investigate the temperature dependence of the yielding behavior of dispersion-strengthened alloys. The alloys studied, MD2100 and MD5100, are SAP-type alloys containing flake shaped aluminum oxide particles dispersed in a matrix of commercial purity aluminum. The proportional limit and 0.2 pct offset stress of both of these alloys were determined as a function of temperature over the temperature range from -190" to 500 C. All tests were conducted on an Instron tensile testing machine. Stress was measured by means of the Instron load cell. Strain was measured by means of SR-4 strain gages attached to the tensile specimens. Stress sensitivity was 80 psi. Strain sensitivity was 2 x 10F Fig. 1 shows the values received for the proportional limit and 0.2 pct offset yield stress plotted as a function of homologous temperature for both the MD2100 and MD5100 alloys. Inspection of Eq. [I] shows that of the terms which determine the theoretically predicted yield stress, uy,, only the shear moduli have an appreciable temperature dependence. From Eq. [I] the yield stress at any temperature T, UT, may be predicted from the yield stress at any arbitrary reference temperature, in this case 25 OC, u25, by the relation where the subscripts T and 25 refer to the values of the property at test temperature and at 25"C, respectively. The temperature dependence of the yield stress predicted by Eq. 121, based on the observed value for the proportional limit at 25OC, is also shown in Fig. 1. In evaluating Eq. [2] the following data was used. The values for the shear modulus of

Jan 1, 1962

By Erle C. Donaldson

A study of subsurface waste disposal in the United States shows that in eight States a wide variety of industrial wastes are being injected into formations ranging in age from Precambrian to Recent. More than 30 wells ranging in depth from 300 to 12,000 feet are used for waste disposal into subsurface formations which include unconsolidated sand, sandstone, vugular limestone, and fractured gneiss.

Jan 1, 1964

In 1961, West Australian Petroleum&apos;s Eneabba No. 1 bore encountered 22 seams of coal totalling 40 ft in thickness between the depths of 6373 ft and 6441 ft. On analysis, this coal had a similar calorific value (8000-HOOO B.T.U./lb, assuming 20 per cent water) to the coal from the Collie Coalfield, Western Australia&apos;s only known area of commercially exploitable coal. Being buried to depths in excess of 6000 ft, the coal at Eneabba had developed weakly-coking properties, and thus, although much younger than the Permian coals of Collie, gave promise of being a major potential source of power for Western Australia.West Australian Petroleum undertook a programme of stratigraphic drilling and shallow test drilling to determine whether this coalhorizon persisted into the outcrop of the Lower Jurassic sediments in the Hill River district, 140 miles NNW. of Perth, and, if it was present, if the quality and quantity of the coal would warrant development of the deposits by open cutting. The coal horizon was identified in the near surface, but the poor quality of the coal and the complexity of the structure made development (in the area examined) uneconomic at the time.A strong seismic reflection in the Eneabba area occurs at the same depth as the Jurassic coals. This event originates within the upper beds of the Lower Jurassic and it is probable that the velocity contrast between the higher velocity siltstones and the very low velocity coals enhances this very strong, distinctive seismic reflection.This event can be followed on continuous seismic data over a large area of the northern Perth Basin, from 13 miles SE. of Dongara to 20 miles SW. of Coorow. It can be followed from a depth of 4000 ftnear Dongara to over 17,000 ft to the SE., so development of thisvast potential source of power will depend on the economics ofprocesses being developed for the production of power from theburning of coal seams in situ.INTRODUCTIONThe discovery of 22 seams of economically useable coaltotalling 40 ft in thickness in the Lower J urassic sedimentsof the Eneabba No. 1 bore (Fig. 1) led to the search forthese seams at economically workable depths. The Ministerfor Mines in Western Australia granted to West Australian1. Supervising Geologist, West Australian Petroleum Pty. Ltd.Manuscript received at The Institute, 25th May, 1964. and presented to the 1964Annual Conference.

Jan 1, 1964

Plant for the production of sulphuric acid from pyrites flotation concentrates was commissioned at Cockle Creek during 1956, to meet increasing demands for commercial acid and superphosphate. Pyrite was chosen as raw material because of the uncertain supplyposition of imported brimstone and the desirability of utilising domestic sulphur.Desulphurisation of the pyrite is performed by two 40-ton per day roasters of the Turbulent Layer type operated under licence from the Badische Analin and Soda Fabrik (B.A.S.F.) organisation. These units are the first of their kind commissioned in the southernhemisphere. Pyrite is fed to the roasters in the as-received un-dried condition. Waste heat steam production is coupled with electricity generation within the plant. Sulphur dioxide is produced at comparatively high strengths and cleaned by conventional cyclone and hot electro-filter equipment.The acid unit has a capacity of 100 mono tons of sulphuric acid per day and includes cooling and wash towers, mist precipitators, a single stage drying tower, 4-pass oxidation section and absorption system.INTRODUCTIONSulphuric acid has been manufactured at Cockle Creek Works since 1913, when the first chamber nitration plant was commissioned. The raw material was brimstone roasted in Herreschoff furnaces. Since that time three additional chamber units have been constructed and have produced acid from brimstone, zinc concentrates, pyrites and -spent oxide, according to changing economic and supply factors.Three chamber units are still in operation. Contact processes have become increasingly important since the first Schroder-Grillo unit was commissioned in 1923. Six of these 5-ton per day units were operating in the mid-thirties, but have since been demolished. Two 15 ton Chemico hot gas contact units commenced operation in 1937 and 1938, and although modified, are still in service.The increasing demand over recent years for sulphuric...

Jan 1, 1957

By Tracy Brettmann

Equipment ? Hollow Stem Auger ? Drill Bits ? Leads/Torque Arm ? Hydraulic Gearbox ? Hydraulic Power Unit ? Grout Pump ? Crawler Crane

Jan 1, 2004

By Erle C. Donaldson

A study of subsurface waste disposal in the United States shows that in eight States a wide variety of industrial wastes are being injected into formations ranging in age from Precambrian to Recent. More than 30 wells ranging in depth from 300 to 12,000 feet are used for waste disposal into subsurface formations which include unconsolidated sand, sandstone, vugular limestone, and fractured gneiss.

Jan 1, 1964

By Y. I. Yang, Y. -B. Tang, D. -J. Ma

Chlorine-containing minerals are commonly present in coal. Associated minerals such as pyrite can undergo exothermic reactions. Consequently, it is of great significance to study the effect of inorganic chloride on the spontaneous combustion of coal. In this study, the effects of five inorganic chlorides (sodium chloride, magnesium chloride, potassium chloride, calcium chloride, and zinc chloride) on the spontaneous oxidation of coal were investigated. Analysis of the gaseous products of coal oxidization at low temperatures (323K to 453K) showed that the presence of inorganic chlorine in coal markedly decreases O2 consumption and the generation of CO and CO2. Samples of raw coal and chlorine-loaded coal were oxidized for 36 hours under the same experimental conditions. Infrared diffuse reflectance spectroscopy results showed that inorganic chloride can inhibit the oxidative decomposition of some functional structure components (methyl, methylene, methine, and hydroxy) in the coal. The influence of inorganic chloride on the oxidation characteristics of the functional groups in coal during spontaneous combustion was investigated using benzyl alcohol and 1-phenylpropanol as model compounds, which were tested under the same experimental conditions as the coal samples. The oxygen consumption of model compounds with and without the addition of inorganic chloride further suggested that inorganic chloride may hinder the oxygenolysis of these structures during low-temperature oxidation. This phenomenon can be attributed to the radical reaction from the perspective of radical chemistry. It can therefore be concluded that inorganic chlorides play an inhibitory role in the spontaneous combustion of coal.

Jan 1, 2015

By A. D. Prokop, J. P. Rider

Along with increased production from longwall units has come the likelihood of increased worker noise exposures. In recent years, equipment has become larger, more powerful, and noisier than its predecessors. For these reasons, the Mining Division of the National Institute for Occupational Safety and Health (NIOSH) is investigating worker noise exposure on longwall faces and researching possible solutions to reduce this exposure. Part of this research effort involves studying the effect of covering the underside of longwall shields with acoustical material to reduce reverberating noise along the face. Experiments using acoustical absorptive insulation to cover the undersides of the shields, shearer body, and the shield supports were conducted at the full scale simulated long-wall test facility located at the Pittsburgh Research Center. Sound levels were recorded every 1.5 m [5 fl] along a 15.2 m [50 ft] section of the simulated face for all of the conditions tested. The analysis of the data indicated that a 2.0-3.0 dBA noise reduction was achieved between the shearer drums and a 4.0-5.5 MA attenuation was attained upwind of the headgate drum.

Feb 24, 1997

By J. R. Kyte, L. A. Rapoport

The material balance equation for partiai or complete 1:trter-drivc reser1,oir.s been re-arranged to include a pressure irrferferencr ternr. This pressure interfernce term was ohtained from the theory established hy Morinda. A .successful progranl deissed to solve the resrclritlg c,qrration in a few hours on a nleelitr .sizeti, digital compuier. No prior knowdelge of the properties of the eqrrifer is required in the solution. 7&apos; ri~rl calculations areatle using various assumed con!binuiions of value of the constant expretsing the qquifer properties correspoinds to the best fit ohtained between observed and calculated field history. Details of the method of calculaion are illus trated by an example. INTKCDUCTICN A method 01&apos; calculating the material balance equation for a partial water-drive reservoir completed in an aquifer has been described in the literature." Pressure interference i&apos;rc,m other pools iocated in the same nquiucr is not taken into account in this solution. When present, the pres- sure interference effect must be included in order to make a complete performance analysis. A correction for this effect has been developed using the theory cstahlished by Mor-tada.&apos; Manual calculation of the material balance for water-drive reservoirs is a formidable task. Such manual ca1culation when interference eflects are includcd would be impossible to completc in any reasonable time period. However, a medium-sized stored program, digltal conlputer can he used satisfactorily. The method is described in the following sections. THECKETICAL CONSIDEKATIOhS The material balance equation for a reservoir producing by partial or total water drive, as proposed by Van Everdingen, This relationship is linear for Z/a from which thc slopc, Z, and the intercept, N, can be obtained by the least-squares method from the data points. It is not necessary lo know the aquifer properties to uktain oplimum values tor 2nd IV. Various assumptions are made tor At,,: where 11 is production time, seconds (oilfield between the equal successive time intervals into which the history is divided. t,, h It, times the number of equal time periods from i.e.. the total dimen-sionless time interval from It is noted that the dinlensionless time interval, At,,, involves all the relevant aquifer properties. Accordingly, any assunlption of is an assumption of the combined aquifer properties which pertain to the solution of the equation. Deviations of the data points from a straight line arc calculated for each assumption of and the value of A, correspond ing to the minimunl deviation is chosen as the optimum solution. This method is described in Ref. 1 and 2. Thc material balance solution is usually made with an initial assumption that the reservoir being studied is located in an infinite aquifer from which there are no other withdrawals. Deviation of the points by amounts greater than can be attributed to inaccuracies in field data may be the result of: (1) boundary effects of a limited aquifer, (2) pressure interference from othcr pools completed in the .sarne aquifer, and (3) a combination of these effects. Differentiation of these effects can be made only on the basis of geologic data. Pressure interference from other fields will result in a pressure drop at the original oil-water boundary having an interference component, The measured instantaneous pressure drops at the oil-water

By G. S. Hill, B. J. Huls

This paper on coarse particle recovery (CPR) summarizes a process to capture coarse particles that are not recoverable by regular flotation. Several porphyry copper operations in the world operate analogous circuits that recover non-floated copper from tailings; however, the case presented here is unique in that extensive underlying test work has allowed the authors to elucidate some fundamental principles behind recovery enhancement. This paper discusses an overview of the flowsheet that is proposed to Minera Escondida Ltda., the nature of copper in the feed to the CPR circuit, and the various unit operations within the recovery circuit.

Jan 1, 2006

By Li Keqiang

This paper discusses the pile foundation of tall buildings in Shenzhen region. For 156 constructed tall buildings exceeding 18 storeys, about 86. 5 per cent of the sum. The two main types of foundation used are the semi?machine?bored/slurry drilled cast?in?situ pile and the excavation pile (hand ?dug caisson). The engineering geologiical condition in Shenzhen was analysed. In general, the bed rock level is not too deep. It belongs to hard rock, but the geologic structure is more complex and the tectonic fissures is plenty. According to experiences of the researches, tests, designs and constructions of pile foundation, we present the basic design principle of pile foundations for tall buildings as follows; (1) pile strength control to select the pile type and to choice the cross sectional dimen­sions, must be in compliance with the strength of the pile. (2) bearing stratum strongly weathered, moderartely weathered and slightly weathered rock may be used as the bearing stratum. (3) bearing pile bored /drilled cast-in-situ pile designed as an end bearing pile. (4) friction pile precast concrete pile, prestressed concrete tubular pile and driven cast-in-situ pile designe as a friction pile. In case, pile design is in compliance with these principles, it may be safe, economical and reasonable.

Jan 1, 1991

By Yves-Laurent Turcotte

Notre conférencier, Monsieur Yves L. Turcotte, Vice-président et Directeur général chez Promaintech Novaxa est diplômé en génie industriel de l?Université du Québec à Trois-Rivières et détient une maîtrise en gestion de projets de l?Université du Québec à Montréal. Il est une véritable sommité canadienne dans le domaine de l?amélioration de la performance des organisations. Provenant d&apos;entreprises manufacturières et de services, il possède plus de 20 ans d?expérience en tant que développeur de technologies, conseiller et formateur auprès d?entreprises. Il a à son actif la réalisation de mandats dans plus de 400 entreprises. Il est reconnu pour sa grande capacité d?analyse et pour trouver des solutions novatrices et profitables aux problèmes des organisations les plus complexes. Aujourd&apos;hui, il dirige Promaintech Novaxa, une division de DMR, qui a célébré son dixième anniversaire en 2006. Cette organisation ayant des places d?affaires dans la région de Montréal, Québec et Vancouver compte plus de 50 professionnels et a une carte de visite dans 16 pays. Les axes d?intervention sont le Management, la Productivité, la Fiabilité, l?Innovation et l?Amélioration Continue.

Feb 1, 2008

By D Pilone

The Tyrrhenian micro-nodules, findable at low depths (200/600 m under s l) are a reasonable reserve of manganese. They can be easily and cheaply recovered but do not contain valuable metals as in the case of oceanic nodules. In this work a hydrometallurgical process for manganese recovery from Tyrrhenian nodules is presented. The studied treatment includes the following operations: magnetic enrichment, reducing leaching, leach liquor purification and electrowinning . The study shows that the most important step in the process is the preliminary manganese enrichment. It can be done directly on the platform reducing not only the transport cost, but also the residue mud in the metallurgical plant. The leaching parameters such as status and size of nodules, temperature, composition of leaching solution and S/L ratio have been investigated. After purifying the leach liquor by iron precipitation as ammonium jarosite , the conditions to electrowin manganese have been investigated. The yields of both manganese leaching and iron precipitation together with current efficiency and specific energy consumption in the electrowinning step are given.

Jan 1, 2000

By Fredrick D. Palmer

The World is Turning to Coal Peabody?s View ?We believe the world is increasingly energy-short, led by unprecedented demand from population centers and economic hubs in Asia, the Middle East and South America ?This occurs as:?Traditional energy sources are clearly constrained, requiring coal-based alternatives?Energy-rich nations leverage political gain from their assets, and nations urgently look to improve energy security ?In this environment:?Oil, coal and gas face a greater long-term convergence, ?Coal?s traditional regionalized nature becomes global, and ?Coal?s compact energy form becomes an attractive source for liquids and substitute natural gas ?The world is blessed with an abundance of coal to help meet all human energy needs

Jan 1, 2008

By Jean-Pierre Côté, Alexandre Noiseux

"Hatch and ArcelorMittal Mines Canada have combined their expertise to develop a dynamic model of the latter’s Iron Ore Pellet Plant in Quebec, Canada. This model was used to predict the benefits of different expansion projects, as well as asses the best implementation sequence.Two modelling tools were used: a discrete-event simulation software used to develop the dynamic model of the Pellet Plant and an in-house process simulator. The latter was based on operational data and known behavior of the process, and was calibrated with historical data gathered under different operating conditions.The results of the process simulator were used as input values for the dynamic model, which included all of the operation steps of the pelletizing process, from concentrate beneficiation to baking of the pellets. The model has been validated by assessing its capacity to represent adequately the operation of the plant during a 20-month operating period. It was able to reproduce the plant capacity within a precision of 1.2%.Simulated “what-if” scenarios allowed quantifying the production increase associated with the addition of new equipment such as ball mills or balling discs, implemented individually or in combination. Results revealed a potential 10% increase in the annual plant production by adding additional equipment in the two most limiting sectors of the plant, grinding and agglomeration. The simulation results made it possible to quantify the synergistic effect of two projects on plant throughput; the model showed that the combination of two projects resulted in a greater production increase than the sum of the same projects evaluated individually.Now that it has proven reliable, the simulation tool can readily be used by ArcelorMittal Mines Canada process engineers to perform simulations for equipment optimization, and to evaluate the impact of various operating parameters such as equipment availability and tonnage, product mix or concentrate quality. This work showed that a reliable model can be developed based on known parameters in combination with the proper integration of the process knowledge."

Jan 1, 2010

By J. D. Miller

Characterization of feed material with respect to expected concentrate grade and recovery is fundamental to the design of improved separation efficiencies and to achieve sustainable development in the utilization of our mineral resources. An important reference point for this characterization is the liberation-limited grade/recovery curve which represents the perfect separation, the best separation which can be achieved for a given feed material limited only by the extent of liberation. Now, liberation-limited grade/recovery curves can be determined based on 3D mineral liberation analysis of feed material. Thus, actual separation efficiencies can be compared to what might be expected for a perfect separation limited only by the extent of liberation. It is shown that 3D mineral liberation analysis based on X-ray micro CT (XMCT) is preferred to 2D section analysis which overestimates the extent of liberation. By way of example, procedures and experimental results are presented and discussed for feed material in the case of phosphate rock flotation.

Jan 1, 2009