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By Jason Ganley, Yingjia Liu, Adam Dekich, William Tilson, Jeffrey Fergus, Dileep Kumar CJ

"Manganese cobalt spinel oxide coatings have been shown to be effective for preventing chromium volatilization from interconnect alloys, and the associated cathode poisoning, in solid oxide fuel cells. During high temperature exposure a reaction layer consisting of chromium containing spine! forms due to reaction with the chromia scale formed on the alloy. The electrical conductivity of this reaction layer is much lower than that of the coating material and thus can increase the overall area specific resistance (ASR) of the system. The approaches to reducing the ASR are to reduce the thickness and/or increase the electrical conductivity of the reaction layer, which includes both the high-chromium spinel phase and the chromia scale. In this paper the effects of transition metal dopants on the amount and properties of reaction products formed during the reaction of spine! oxide coating materials with chromia are presented.IntroductionThe high cost and difficulties involved with the processing of chromia based ceramic interconnect materials for SOFCs are driving the search for metallic interconnects [1, 2]. The reduction in the operating temperature of SOFC has allowed for the use of high chromium alloy steels for this application [3]. However, the volatilization of chromium from the chromia scale, and the associated poisoning of the cathode, remains a problem which needs to be addressed [ 4]. Though the application of manganese cobalt oxide spine! coatings on the alloy surface substantially reduces chromium poisoning of the cathode [5], the low electrical conductivity of the reaction layer formed between the chromia scale and coating affects the performance of interconnect. Incorporating transition metal ions in the reaction layer could alter the electrical characteristics and improve the performance. Copper and nickel doped manganese oxide spinels are widely used as thermistors due to their high electrical conductivity and negative temperature co-efficient of resistance characteristics [ 6, 7]. Hence doping of copper and nickel in manganese-cobalt spine! oxide composition may improve the electrical characteristics of interaction layer as well and is attempted here."

Jan 1, 2012

By B. C. Viljoen

"SynopsisCommencement of the next phase of the Lesotho Highlands Water Project is a year or so away from becoming reality. Some 50 km of tunnels in the form of access adits, shafts, diversion tunnels, and main waterways will be constructed. Sprayed concrete will form an integral part of the temporary and permanent rock support systems that will be installed. Furthermore, the use of sprayed concrete as a final tunnel lining solution was proposed as a viable alternative to concrete linings in the feasibility studies that preceded the forthcoming implementation phase.The aim of this paper is to make the reader aware of all the sprayed concrete related issues that engineers tend to grapple with during the design and construction of tunnel projects and other underground works. Primarily, these issues would include selection of applicable design parameters, technical specifications, construction application methods, quality control and, most importantly in the context of final or permanent linings, the durability of sprayed concrete.The International Tunnelling Association (ITA) Working Group (WG) 12 has been tasked specifically to publish a set of recommendations on the Quality and Control of the Application of Sprayed Concrete and the Testing of Sprayed Concrete for Durability. These tasks were also further explored at the recent World Tunnel Congress (WTC 2015) that was held in Dubrovnik, Croatia at the end of May 2015.IntroductionSprayed concrete is presented in a variety of shapes, designs, forms, application methods and accompanying terminologies including shotcrete, gunite, pneumatically applied concrete, and the like. The International Tunnelling Association (ITA) decided to standardize on a single terminology, namely ‘sprayed concrete’, in order to simplify specification, interpretation of guidelines, and codes of practice."

Jan 1, 2015

By J. R. Thoenen

Occurrences of titanium, zircon, and other heavy minerals are widespread in Florida. Deposits concentrated as "heavy sands" by wave and wind action have been mined an or near Atlantic coastal beaches since 1916. An important inland concentration at Trail Ridge; .believed, to have formed along an ancient share line, was disclosed by preliminary investigations (1947) by the Bureau of Mines. This report describes investigations to determine the extent and grade of "heavy-sand" concentrations in other inland stabilized dune areas in the central and northeastern parts of the peninsular region of the State (fig. 1). Portions of the central highlands south of Trail Ridge and terraces and dunes in the coastal lowlands region, east and northeast of the ridge were investigated. Holes were drilled in 10 areas (see table 1 and fig. 2) along State and County roads and on private property. They were spaced 250 to 2,000 feet. apart to obtain a cross-sectional picture of "heavy-sand" content in the dune areas. These sections were generally placed in east-west directions normal to the general trend Of the peninsula to intercept one or more of the ancient shore lines in the various areas (figs. 3 to 13, incl.). A total of 433 drive piped and 333 jet holes were drilled, and 7,293 bulk and core samples were taken. Intermediate holes were placed at closer intervals when field analysis indicated 1 percent or more of heavy minerals present. All of the holes drilled and the analysis of samples that contain 1 percent or more of heavy minerals are listed in table 2. Profiles (figs. 14 to 20, inclusive) show the more favorable concentrations, which are irregular in outline and erratic in mineral content. The highest concentrations averaged 1.0 to more than 2.0 percent heavy-mineral content, but a few individual hole samples exceeded 3.0 percent in grade.

Jan 1, 1949

By William B. Hughes

The rubber-sleeve core barrel was developed to improve core recovery from unconsolidated sands, where it is most difficult to obtain cores with conventional barrels. The use of a rubber-sleeve core retainer, together with other departures from clsual design, has required a considerable amount of testing to prove its op-erability. Tests run in shallow experimental holes and in drilling wells in the U. S. and Vemzuela have, to a large extent, proved the operation of the barrel. Internal mechanism troubles, such as sandbinding of the sleeve, have been largely overcome. Cores have been recovered from completely unconsolidated sands where conventional coring has almost been abandoned because of poor recovery. In addition to retaining the core until brought to the surface, the barrel gives a "packaged-ar-cut" core, which is coilverzient for handling and transportatiorz. In the initial work, drag blade cutters, roller cutters, and tungsten carbide insert cutters were usrd for cutting unconsolidated sands. Further bit head development is presently being conducted using diamond heads in unconsolidated sands where shaler, hard sands, and limestones are encountered in adjacent formations. Thir work should render the barrel capable of cratting and recovering most types of formations, possibly including broken and frac- tured fornlations. This development is being carried on in cooperation with a diamond bit manufacturer. INTRODUCTIO N For many years the oil industry has needed greater recovery of cores from unconsolidated formations. Conventional equipment has been used to core unconsolidated sands with little success. Specifically, a core barrel was needed which would recover unconsolidated sands in a condition that would give useful reservoir information. DEVELOPMENT OF 'THE RUBBER-SLEEVE CORE BARREL Basic Requirements of Unconsolidated Sand Corino The basic need was defined as a core barrel that would obtain a continuous unconsolidated core with sand grains in place as deposited in the formation. A preliminary survey of coring equipment and search of the literature pointed out the weaknesses of conventional core barrels. Laboratory tests using unconsolidated sand in a metal tube simulated actual sand movement into the core barrel during conventional coring. In conventional barrels the core sometimes crumbles and bridges, or fails under compressive column action, becomes oversize, and wedges against the walls of the inner barrel. The core barrel requirements established by the surveys and preliminary tests are as follows. 1. The core should be held to- gether as it is cut so it cannot crumble and bridge against the walls of the coring tool, care being taken not to permit damage from fluid circulation. 2. The core should be continuously supported as it is cut so it will not have to support itself in compression. 3. The core should be packaged in the barrel to retain an undisturbed condition during the trip out of the well. The packaging should be such that the core can be removed from the barrel and shipped to the core analysis laboratory without physical disturbance or alteration of fluid content by exposure to the atmosphere. Operation of the Rubber-Sleeve Core Barrel The rubber-sleeve core barrel (Fig. 1) meets the basic requirements for the recovery of unconsolidated sands.

By Clarissa Hadad de Melo, Jean André François Dille, Rosa Maria Sales da Silveira, Rafaella Martins Ribeiro, Leonardo Sales Araujo, Luiz Henrique de Almeida, Alessandra Vieira Guimarães

Este trabalho tem por objetivo investigar o efeito do Y na precipitação da fase δ na superliga de níquel 718 e correlacionar a caracterização microestrutural com a precipitação/dissolução das fases, por análise térmica. As ligas A, B e C solubilizadas e superenvelhecidas foram caracterizadas por microscopia eletrônica de varredura e de transmissão, com o auxílio de EDS para identificar as fases presentes nas ligas. A caracterização microestrutural foi corroborada com técnica de calorimetria diferencial de varredura. Resultados mostraram que a adição de Y influencia no tamanho de grão e consequentemente na fração de δ precipitada. A adição de Y modificou a cinética de precipitação de δ, que variou de acordo com o teor de ítrio adicionado.

Oct 13, 2019

By D. Turnbull, H. N. Treaftis

Precipitation of tin from Pb-Sn alloys (lead-rich) occurs by the nucleation and growth of hemispherical cells which consist of tin lomelloe interspersed in the depleted solid solution. Nucleation and growth of these cells and the tin interlamellar spacing at various compositions and temperatures have been investigated. The interlamellar spacing increases approximately as the reciprocal of the logarithm of the supersaturation ratio. For constant initial tin concentration the concentration of cell nuclei increases with decreasing temperature to a limiting temperature-independent value. The kinetic results support the view that the cell growth rote is governed by the diffusion of tin along the cell boundary. In the main, the results confirm the authors' earlier deductions, drawn from resistometric and calorimetric data, about the precipitation mechonism. IT has been shown1, 2 that tin (ß) precipitates from lead-rich (a) PbSn solutions by the nucleation and growth of cells (cellular or discontinuous precipitation). These cells consist of tin lamellae, with a spacing 1, interspersed in a depleted a solution. Reorientation of a also accompanies cell growth. The kinetics of cellular precipitation of tin from lead have been measured by resistometric2, 3 and ca1orimetric1, 3 techniques. The time-transformation isotherms (t equals time; x, volume fraction of specimen transformed) of the initial rapid precipitation, which drains about 60 pet of the tin from solution, have been described by a kinetic law having the form x = 1 —exp (—bt n) [I] where n usually has the value 3.0. It was shown" that this law and the other kinetic facts can be explained satisfactorily if it is assumed that the cells grow at a constant rate and that all the cells nucleate in a time negligible in comparison with the period of cell growth before impingement. Thus, for hemispherical cells b = (2/3)pNG3 [21 where G is the rate of cell growth in cm per sec, and N is the number of cell nuclei per unit volume. The rapid rate of cell growth at low temperatures can be accounted for"' if it is assumed that the dissolved tin drains to the lamellae edges by diffusion along the sweeping cell boundary rather than by diffusion through the a crystal (volume diffusion). For cell growth governed by cell boundary diffusion it was shown, approximately G=2(X° - X° / X° ) DBA / l2 where A equals the thickness of the cell boundary; D R, the coefficient of diffusion of tin atoms within the boundary; and X° and X, are the atom fractions of tin in the supersaturated and saturated solutions, respectively. Zener8 had already shown that, where

Jan 1, 1959

By Fred P. Peters

T. D. Yensen.*—As my information is of a negative nature, I think it belongs under this paper. We are particularly interested in magnetic materials and we would like very much on occasions to make use of powder metallurgy. We have tried repeatedly to use powder metallurgy in preparing our nickel alloys but always. with negative results; that is, we cannot get as good magnetic properties by powder metallurgy as we can by starting with a molten material. We have tried by all possible means to make materials' like 50 per cent iron-nickel alloys by powder metallurgy. The compacts can be regularly lorged and rolled but no matter what we do in the way of annealing, the magnetic properties come out very much poorer than if we start with molten material. F. V. Lenel. †—I want to mention one characteristic of articles made from metal powders which distinguishes them from die castings; that is, their wear resistance. Die castings usually are made from zinc or aluminum alloys and a few copper-zinc alloys; all of them are comparatively soft and not very wear resistant. I know of a number of cases where powder metallurgy rather than the die-casting method was used for producing a certain part because higher wear resistance was needed than could be attained in die castings. A, J. LanghammeR.*—The subject of powder metallurgy is somewhat difficult to discuss, and portray, in the time that his been allotted. Most of you would rightly be bored if we went into details. However, I will cite one incident that possibly will help illustrate some of the potentials. Last summer I was in Washington and met Navy officials for the purpose of studying the possibility of making a certain part by powder metallurgy. The part is highly intricate and I happened to remark that the material cost would be high; that is, the cost on one raw material. Promptly a high-ranking Navy officer said: "Mr. Langhammer, if you must pay x dollars a pound for the raw material, but achieve the desired results, the cost of the finished part would still be low."

Jan 1, 1945

By S Kundu, J Zanganeh, D Eschebach, B Moghtaderi

The concentrations of methane and coal dust vary from one location to another in underground coalmines. In the presence of an ignition source, such as static electricity, these mixtures can initiate explosions and consequently cause massive destruction. Research data can help in understanding the level of hazards and associated risk these flammable mixtures can produce. For instance, the level of peak explosion pressure and flame speed can be well understood from experimental and numerical research data. With this aim, methane–air mixtures and methane-coal dust-air mixtures were employed in a ducted spherical vessel. According to literature, the maximum value of peak explosion pressure can be obtained in vessels of spherical geometry when compared to vessels of other geometries. Thus the values of explosion parameters generated from spherical vessels can be incorporated in understanding the highest level of hazard that can occur in a real world scenario.In this study, the duct integrated with the vessel resembles any channel or pathway connected to a methane and/or coal dust rich area in the mine. Experimental investigations emphasise that the severity of explosion in the explosion zone transmits to the channel or pathway. The length of the channel or pathway also plays an important role on the values of explosion parameters. The greater the length of the channel or pathway, the higher the explosion pressure is and therefore the higher the destruction. Ignition energy and concentrations of methane and coal dust were varied in collecting experimental data. The data of explosion parameters thus obtained can be employed in addressing hazard mitigation strategies in coalmines.CITATION:Kundu, S, Zanganeh, J, Eschebach, D and Moghtaderi, B, 2017. Incorporating research data in addressing methane and coal dust fire, and explosion hazards in coalmines, in Proceedings Australian Mine Vent Conference 2017, pp 175–180 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

The application of cost updating with the aid of cost indices is reviewed with particular regard to the mining industry. Examples of applicable cost index series are included with values given for the last ten years. The compilation of the indices is discussed with consideration given to the possible sources of error inherent in their application to specific mining cost problems.

Jan 1, 1990

By H. Sarvamangala

Biomineralization of manganese on titanium condenser material exposed to seawater has been illustrated. Biom-ineralization occurs when the fouling components, namely, the microbes, are able to oxidize minerals present in water and deposit them as insoluble oxides on biofilm surfaces. Extensive biofilm characterization studies showed that an alarmingly large number of bacteria in these biofilms are capable of oxidizing manganese and are, thereby, capable of causing biomineralization on the condenser material exposed to seawater. This paper addresses studies on understanding the exact role of the microbes in bringing about oxidation of manganese. The kinetics of manganese oxidation by marine Gram-positive manganese oxidizing bacterium Bacillus spp. that was isolated from the titanium surface was studied in detail. Manganese oxidation in the presence of Bacil-lus cells, by cell free extract (CFE) and heat-treated cell free extract was also studied. The study confirmed that bacteria mediate manganese oxidation and lead to the formation of biogenic oxides of MnO2, eventually leading to biomineralization on titanium surface exposed to seawater.

Jan 1, 2008

By Hennessy F. L

It is generally recognised that slags are active participants in pyrometallurgical processes, and not merely inert liquids which must be produced. to effect separation of gangue material in smelting, or of impurities in refining. The importance attached to slag-metal reactions in steelmaking is shown by the numerous investigations in this field. However, there are still many important reactions of slags which require explanation. In this paper some new aspects of the reactions of slags will be discussed, as far as possible quantitatively.FREE AND COMBINED OXIDESMetallurgical experience indicates that variations in the composition of slags produce changes in the chemical behaviour of the various components. These variations have been generally ascribed to changes in the proportions of free and combined oxides, i.e., compounds have been assumed to be present in the liquid slag.Considerable support for this view has been adduced from the existence of compounds such as metallic silicates, phosphates, etc., in the solIdified slag. However, this does not imply that such compounds necessarily exist in the molten slag.The most direct evidence as to the nature of molten slag is to be obtained from a study of the liquid state. In...

Jan 1, 1950

By T. R. Wildeman

"At the Big Five wetland, which was built to treat drainage from a metal mine, encouraging results have attributed to sulfate reduction. Cu and Zn were reduced to below detection limits of 0.50 mg/L, Fe was reduced by at least 90% to below 3 mg/L, and the pH was raised from below 3 to above 6. The study showed that treatment was primarily through microbial processes within the substrate and that plants were not needed to insure success.Constructed wetlands can be taken through design and proofing stages, and into operations scale in a meaningful time frame for on-line acid drainage remediation. In staged design, laboratory experiments are initiated to determine reasonable substrate materials for remediation of a particular drainage. When a reasonable substrate is found, bench scale experiments are initiated as the next stage in the design. In these studies, removal efficiency, permeability, and flow are analyzed to identify candidate substrate which will support sulfate reduction and be hydraulically reasonable. Using this design method at one site, an acid drainage of pH 2.5 was raised to a pH of above 7. Total heavy metal concentrations in this drainage exceeded 900 mg/L. In the pilot constructed wetland Cu, Zn, and Fe were reduced by 99%.Determining how well these anaerobic cells operate in the winter is done at the pilot plant site in Idaho Springs, CO. It's been found that over the last four winters, those cells that emphasize anaerobic removal within the substrate have operated continuously and effectively the year round. Winter operation is aided by the fact that the water temperature of the acid drainage is always between 14 and 16° C, and the cell can be readily insulated from the cold. Activity of the sulfate reducing bacteria may decrease during the winter. However, it appears that organic complexation of metals helps to maintain low concentrations of metals in the effluent."

Jan 1, 1992

This chapter summarizes data on crude mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are tables that show the principal mineral commodities exported from and imported into the United States, and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at 'any of several stages of extraction and processing, the stage of measurement used In this chapter is what is normally termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the product of auxiliary processing at or near the mines.

Jan 1, 1977

By I. P. Barbosa, P. S. M. Soares, I. O. C. Masson

"Permanent magnets have been applied extensively to several electronic products such as printers, TV sets, microphones, microcomputers and headphones, presently manufactured in large scale by industrial economies. Sm-Co alloys represent about 20% of the world market for permanent magnets and their industrial processors generate 20-30% of magnetic scraps which can be recycled. This paper discusses a process route to recycle SmCo5 using acid treatment, solvent extraction of Sm and electrowinning of Co. The results confirm the feasibility of the alternative proposed. Basic operational variables are suggested as guidelines to design a plant for recycling magnetic scraps.The use of hydrometallurgical processes to recycle scraps from the industry of permanent magnets has been suggested in some recent papers related to recycling of metallic alloys [ 1 ]. These research efforts might be understood as a worldwide tendency towards the development of self sustainable metallurgical processes which mean the reduction of environmental impacts.CETEM -Center for Mineral Technology leads in Brazil several research programs concerning recycling and treatment of industrial residues. The work on samarium purification and concentration by solvent extraction, producing also a solution of cobalt sulfate as partially reported here is one of these programs. Previous results related to the sulfuric acid digestion of SmCo5 are presented somewhere else [2]"

Jan 1, 1997

By W. J. Young, K. B. Macneill, C. N. Smith

"A BRIEF HISTORY OF THE MURRAY BROOK MINERAL DEPOSITDuring the mid-1950's intensive exploration activity in northern New Brunswick followed the discovery of the world class Brunswick base metal deposit. Using the prototypes of modern airborne geophysical and geochemical exploration techniques many mineralized areas in the Bathurst-Newcastle area were quickly identified. This base metal - silver camp is situated within the metavolcanic - metasidementary rocks of the Tetagouche Group which forms a roughly circular caldera-chaped voloanio complex of Ordivician age.One of the early results in the exploration history in the camp was the discovery of the Murray Brook Deposit by Kennco Explorations, (Canada) Limited. During routine ground checking of geophysical anomalies, most of which turned out to be graphitic schist, the discovery of some copper bearing float was made by the exploration team. This encouraged the company sufficiently to carry out a regional stream sampling program which lead to a large anomaly associated with a hematitic gossan. Diamond drilling of a weak Slingram anomaly over the gossan zone resulted in the discovery of massive sulphide lenses. This was followed in 1956-7 with an intensive drilling program. The result was the delineation of a potential ore body containing an estimated 23 million tons with an overall grade of 0.44% copper, 0.86% lead, 1.95% zinc, 25.73 g/tonne (0.91 oz/ton) silver, 0.28 g/tonne (0.01 oz/ton) gold. Within this package were higher grade zones of copper and lead-zinc mineralization approaching ore grades.A thick blanket of gossan was present and is reported to have caused the drillers considerable trouble as they attempted to penetrate it to get to the underlying sulphides. The gossan, consisting of iron oxides and silica fragments sits on top of the massive sulphides and attains a remarkable thickness of 45.5 meters (150'). Early work had suggested that the gossan was enriched in gold and silver. If this were the case and if the precious metal could be leached out with cyanide, then mining and recovering those values might be economic.With this in mind Northumberland Mines Limited optioned the property from Kennco in 1985. Preliminary leach tests indicated that indeed the gold in particular leached readily. Subsequent drilling of the gossan (using triple core barrel technology for better recovery of the easily ground core) indicated 1,536,363 tonnes (1,690,000 tons) with an average grade of 1.05 g/tonne (0.037 oz/ton) gold and 42.13 g/tonne"

Jan 1, 1993

By R. J. Gajan

As part of its research program on secondary metal refining, the Federal Bureau of Mines has developed a fast method for determining aluminum, iron, copper, cadmium, and lead in zinc-base alloys. The new method is intended for use by trained technicians in laboratories with inexpensive equipment. It can be used either in the analytical laboratories of the many small plants that are characteristic of the secondary metals industry or in laboratories engaged in basic research to improve refining processes. A complete analysis for the foregoing elements can be made in less than 3 hours from a single sample in solution. The method is especially helpful when a small amount of sample is available. Aluminum and iron are determined spectrophotometrically and the other elements polarographically. The new method is now being used for control analysis in metallurgical research, and the results compare favorably with previously used spectrographic methods. Luke and Braun4/ described a photometric method for the determination of aluminum in zinc diecasting alloys in which the aluminum was complexed with Aluminon reagent (ammonium salt of aurintricarboxylic acid), forming a red lake. An adaptation of this method was used for determining aluminum. Beers law is obeyed between 0.01 and 0.06 milligram of aluminum.

Jan 1, 1961

By Franklin M. Grynkewicz

The subject of bearing pile performance installed by vibratory hammers has been a matter of increasing study and continued controversy. A recent case study from a major bridge replacement project is discussed which provides encouraging data on the use of vibratory pile hammers as a primary means of pile installation and also presents the problems associated with its general acceptance. The bridge project case study foundations consisted of HP 14 x 89 pile sections, designed to develop capacity primarily in friction. Preliminary tip elevations were determined by traditional static analyses. Production pile installation was performed using an IHC S-70 Hydro-Hammer. Driving criteria and final production pile tip elevations were determined after preliminary indicator pile drive tests and static load test results at bridge pier cofferdam locations. Based on impact driven production pile performance, the Contractor wished to investigate vibratory driven piles as a means to accelerate construction schedule. Dynamic pile testing procedures were used as the primary measurement tool and test results were compared to the production pile drive records and prior static load tests. Field testing consisted of driving and monitoring with the PDA impact driven piles to the design tip elevation. Three vibratory driven piles were installed to the same tip elevation and immediately subjected to impact driving and dynamic testing to compare dynamic pile resistance. The results indicated that the site soil conditions were favorable for vibratory pile hammer installation. Recommendations and procedures for proceeding with vibratory hammer pile installation were presented to the Owner. These procedures included quality control in conformance with latest AASHTO recommendations. The Owner, in spite of the site specific data base and QA/QC procedures, would not accept vibratory pile hammer installation, due to the absence of precedence. It is concluded that for vibratory methods to become accepted a rational method of analysis, design and field QA/QC procedures requires development. In addition, the engineering community and Owners/Agencies must be more open to alternate methods of foundation construction. The continued development of dynamic methods of monitoring vibratory pile installation is considered to be key to the general acceptance of this installation procedure.

Jan 1, 1991

Overview ?Oil Sands Background ?Water Use in Surface Mining ?Tailings Disposal ?Water Balance for Surface Mining ?Implications of Emerging Regulations ?Water Management Framework ?Tailings Performance Criteria (Directive 074)

May 1, 2009

By Yasser Mohamed

Daily field management of earthmoving operations requires quick and regular decisions for allocating available equipment to different jobs on a project. A general foreman?s day starts with matching several activities with a suitable set of available equipment to achieve the highest productivity and lowest unit cost. Usually, this decision-making process needs to be quick, and depends to a great extent on the foreman?s experience, which varies from one individual to another. Many analytical solutions with various degrees of sophistication and optimization exist to address such decisions. However, adopting any of these solutions is contingent on how accessible and easy-to-use the solution is. This paper discusses the development process of a webaccessible solution for evaluating earthmoving fleet composition and allocation scenarios. The solution relies on discrete event simulation and an optimization backend engine, but introduces the user with a simplified and easy-to-use interface that is accessible from any mobile device, and is customized to specific user?s needs. The developed system gathers most equipment and site-related input data from a company?s information systems to minimize user input. The user mainly needs to formulate equipment and job combinations and allocation scenarios (e.g. soil type, quantity, and hauling distance), according to equipment availability each day. Then the system will evaluate the productivity and unit cost estimates for each scenario, allowing the user to choose the most suitable one. It may also be used to automatically recommend the optimum solution given an available list of equipment. The paper presents the process followed in prototyping the proposed system in collaboration with a major Canadian earthmoving contractor, and customizing it to the user needs within the company. It also describes the overall structure of the developed system and its core simulation model.

Aug 1, 2013

By Steven M. Rupprecht

"The artisanal mining sector in Central Africa is largely informal, yet provides an essential livelihood for many (directly or indirectly) participants, as well as facilitating an important source for the flow of income into many communities. Artisanal mining varies from site to site, but appear largely well structured despite its informality. The artisanal mining sites in Central Africa have some inherent management structure and the extraction itself is often organised. Artisanal mining is labour intensive and is generally conducted utilising hand digging methods e.g. shovels or hand chisels. Artisanal mining is generally more dangerous than small-scale or large-scale modern mining operations. This is especially true as artisanal operations are generally subsistence activities with artisanal miners focusing more on immediate concerns than the long-term consequences of their activities. When miners have no other source of income, they will usually find ways to evade controls and carry on working. The objective, through proper/dedicated training of artisanal miners is to migrate Artisanal mining to establish a small-scale mining (SSM) industry in Central Africa. Through developing the necessary skills in the fundamental areas of mining it is proposed that Artisanal Mining can become more productive and safer mining operations. The paper reviews the above focus areas, highlighting the skills and tools that are necessary to assist in establishing a sustainable small scale mining industry migrating from manual labour to semi-mechanised mining and processing. The purpose of the transformation process is to create a safe, healthy, environmental and community oriented mining operation with the objective to uplift the skills and wealth of the mineworkers and the general community."

Jan 1, 2015