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By N. A. Warner

To filly secure the environmental and social acceptability benefits of making a sulphide smelting facility and its ancillary sulphuric acid plant or other means for fixing sulphur, a virtually zero gas emission operation, it will be necessary to utilise exclusively technically pure oxygen. The strategy proposed for preventing the smelter from overheating involves highly efficient energy transfer by promoting sulphur trioxide formation at a relatively higher temperature than normal. A closed-loop gas circuit uses an eductor system actuated by the process oxygen to recirculate sulphur trioxide and unconverted sulphur dioxide back to the smelter, the endothermic dissociation of sulphur trioxide becoming a major contributor to the removal of excess heat. The only gases leaving the system relate to the bleed of nitrogen impurity introduced in the tonnage oxygen.

Jan 1, 1998

By R. W., Ludt

THE use of froth flotation for the separation of minerals has become one of the most important of ore dressing processes. Its particular adaptability to the enrichment of low grade ores has made the process an important factor in the national economy. The methods have been extended to the recovery of a great number of minerals. Among the few minerals which have resisted efforts toward industrial flotation is chrysocolla, a hydrated partly colloidal copper silicate. Chrysocolla, being a product of natural oxidation, has been found to occur in small quantities with many ores which are recovered by flotation methods. In present practice, these small quantities of copper silicate pass off with the tailings and are lost. The advantages to be gained by a satisfactory process for the recovery of chrysocolla is apparent. Any application of principles which points a way toward the satisfactory industrial flotation process for copper silicate would be of advantage. This paper presents an attack on this problem.

Jan 1, 1949

Although anion exchange resins are widely used for gold recovery in Russia and the former CIS, accounting for almost 50 percent of gold recovery in that part of the world, the technology has not been adopted in the West, apart from one small operation in South Africa. This situation is likely to change as the gold industry heads into the twenty first century. With gold prices having declined steadily through the 1990's, mining companies are under great pressure to reduce costs and improve gold recovery. Most studies on the use of resins for gold recovery from cyanide solution or pulp have shown that this technology has the ability to achieve both these goals. Resins can also be used to recover and recycle free and complexed cyanide in gold plant tailings, which has the potential to significantly lower operating costs, and latest developments in this area of technology are discussed. Finally, recent studies on thiosulphate leaching of gold have'shown that this process is very well suited to the treatment of carbonaceous, preg-robbing ores from the Carlin trend (Nevada, USA), and elsewhere in the world, because the gold thiosulphate complex does not load on to carbon. Whilst this obviously benefits the leaching process, it means CIP and CIL are ineffective in this situation, and the use of ion-exchange resins for gold recovery from thiosulphate leach solution are discussed.

Jan 1, 1998

By Fernanda Moreno Rodrigues

A adição de elementos microligantes para o controle do crescimento do grão austenítico vem sendo largamente utilizada nas últimas décadas. O Nióbio é tido como o elemento mais importante deste grupo, pois produz precipitados finos na matriz que ancoram os contornos de grão, retardando o seu crescimento. O presente trabalho avalia o efeito do Nióbio no tamanho do grão austenítico do aço VEX, um aço ferramenta para trabalho a quente utilizado para extrusão de alumínio. O estudo baseou-se na comparação entre duas composições químicas, uma sem Nióbio e outra com microadição de 0,02%. Ambas foram caracterizadas microestruturalmente e quanto à tenacidade. O tamanho de grão foi avaliado após austenitização entre 980°C e 1.200°C. Os resultados mostram que a adição de Nióbio é efetiva no refino de grão em elevadas temperaturas, o que é relevante para a aplicação industrial do aço em questão.

Aug 7, 2018

By Teena Redhorse, David Tsztoo, Anthony Yu

"Since ancient times, storing and conveying water via underground water systems and tunnels has been touted for its strategic advantages. Underground cisterns and tunnels assured protection of essential fresh water supplies from man made contamination and especially from enemies who would gain an advantage by disrupting an adversary’s water supply in a siege. Modern day engineers do not usually specify tunnels for reasons of avoiding deliberate contamination or siege — however, they are just as enamored with the idea of building tunnels for water conveyances.Such was the case for the San Francisco Public Utilities Commission (SFPUC). The SFPUC provides drinking water to 2.6 million residential, commercial and industrial customers in the San Francisco Bay Area. The SFPUC’s water system includes 257 km (160 miles) of transmission pipelines and tunnels from the SFPUC’s largest reservoir, the Hetch Hetchy Reservoir inside Yosemite National Park, to San Francisco. About 129 km (80 miles) of the system consist of tunnels. A 30-km (19-mile) section of the tunnel network, called the Mountain Tunnel, was thought to be at risk of a catastrophic failure in its concrete-lined section of 18 km (11 miles). For much of the project planning process, a new replacement tunnel was presumed to be required according to the tunnel planners.Originally constructed between 1917 and 1925, the Mountain Tunnel has been in continuous service since 1925. The 30-km (19-mile) tunnel is located downstream of the Hetch Hetchy Reservoir water source in Yosemite National Park, between the Early Intake and Priest Reservoir (Fig. 1). Approximately 18 km (11 miles) of the tunnel is lined with unreinforced concrete. Though the condition of the tunnel was being monitored through water sampling and periodic inspections, there was growing concern that the tunnel lining was at risk of a partial collapse that could interrupt water delivery for up to nine months. The SFPUC was faced with a decision to construct a new bypass tunnel to replace the lined section of the Mountain Tunnel or to rehabilitate the existing tunnel."

Jan 6, 2018

By Roger T. Laine

"The Carswell structure, located in the western part of the Athabasca Basin, northern Saskatchewan, has been extensively explored since 1967. This exploration has been successful and lead to the discovery, in 1970, of the D sandstone-hosted unconformity related deposit. By the end of 1984, five additional basement-hosted unconformity related deposits had been delineated: the OP and N discovered in 1970, the Claude in 1971, the Dominique-Peter in 1981, and the Dominique-Janine in 1984. The D deposit has been mined out; the Claude open-pit has already produced more than 500 tonnes of uranium, the development of the Dominique-Peter underground mine (first phase) has been completed, and production from the latter started in 1985.All six deposits are located in the southern part of the Aphebian metamorphic core, 18 km in diameter, which has intruded at least 1250 metres of Helikian Athabasca Group sediments during a cryptoexplosion event at 480 Ma, unrelated to the emplacement of uranium mineralization. The metamorphic rocks, affected by the Hudsonian Orogeny, are divided in two lithostratrigraphic units: the Peter River gneiss, aluminous gneiss series, and the Earl River complex, mixed quartzofeldspathic and mafic gneiss series. A well developed regolith profile is recognizable in the south along the contact with the sandstone and inside the metamorphic core sometimes associated with conformable sandstone beds.Basement and sandstone-hosted uranium deposits show many similarities:-linkage to unconformity;-mineralogy and geochronology with a first phase mineralization characterized by a polymetallic sulphide-uraninite-brannerite assemblage dated at 1150 to 1050 Ma, a second phase characterized by a simple sulphide-uraninite assemblage dated at 890 to 820 Ma, and a third phase characterized by a pitchblende-hematite dated at 380 Ma; and,-linkage to early Hudsonian structures with remobilization of these structures during intense hydrothermal alteration resulting in Mg chlorite-illite halos."

Jan 1, 1986

By Flávia Vieira Braga

O efeito da temperatura de deformação a quente na textura cristalográfica de um aço inoxidável ferrítico AISI 430 estabilizado ao Nióbio foi estudado por ensaios de torção a quente. A laminação de acabamento em laminador Steckel foi simulada utilizando diferentes faixas de temperatura, buscando promover o amaciamento por recristalização. Após cada ensaio, as amostras foram temperadas até a temperatura ambiente objetivando a análise das microestruturas geradas. Foram também realizados ensaios de torção interrompidos visando avaliar a ocorrência da recristalização entre passes. A técnica de EBSD foi utilizada para analisar a microestrutura das amostras ensaiadas, a textura formada e o tamanho de grão. Foi observado que a de temperatura de simulação que mais favorece a ocorrência da recristalização estática está entre 900 e 840 ºC e o tamanho de grão resultante é menor em tais condições. A textura de torção obtida está em concordância com a literatura.

Aug 16, 2017

By D. Harrington

The coal-mining industry of the United States finds difficulty not only in making ends meet financially but also in operating with anything like reasonable safety. The record to date has not been particularly good as to either finance or safety, but at least in some phases or safety there are indications of better times to come. During the fiscal year ending June 30, 1929, only 139 lives were lost in explosions in our mines as against 342 lost during the fiscal year ended June 30, 1928; this decrease in such fatalities is definitely a matter for satisfaction. During the fiscal year July 1, 1928, to June 30, 1929, the attention of the safety division of the U. S. Bureau of Mines was directed to 38 mine explosions in the United States. Two explosions were in non-coal mines, one in a semianthracite mine, two in anthracite mines, and 33 in bituminous mines. These were not all major explosions - that is, explosions in which five or more lives were lost; in some of the explosions no lives were lost, while in others fewer than five fatalities resulted. Table 1 gives data on the explosions, showing the number of mines using open or closed lights and the number of explosions with resulting deaths, by causes, for each State.

Jan 1, 1929

By Fernando Henrique Gomes de Souza

Techniques which use a spring to supply the bias force to actuator are well adopted since they are inexpensive and simple to construct. In this work it was design an actuator concept using bias-type device technique, which comprises two coils that mutually push against each other to supply the stroke. For the coils springs, it was used a wire of NiTi shape memory alloys (SMA) and a wire of 400 grade maraging steel as construction materials.

Aug 8, 2018

By Vinay Kumar

The present investigation describes R & D studies carried out for recovery of copper from the sulfate solution expected from the leaching of e-wastes in presence of minor constituents such as cadmium, zinc and nickel using solvent extraction process. In order to extract copper in continuous mode in mixer settler unit (MSU), basic studies have been made to optimize the experimental condition using 5%LIX84 in kerosene. Subsequently, the solvent extraction of copper was made in MSU maintaining leach solution flow rate 4.0 L/h and A/O ratio 1. The results showed complete extraction (~97%) of copper in three stages at A/O ratio 1 from the aqueous solution containing 1.98g/L Cu at pH 1.91 in presence of impurities. Loaded metal was completely stripped after scrubbing with 10% sulfuric acid in two stages. The stripped solution could be used for metal/ salt recovery by electrolysis/ crystallization.

Jan 1, 2010

By Norman A. Jull

"IntroductionThe scope of this paper is intended to deal mainly with cyclones in grinding circuits. However, the section on Cyclone Equipment, contains more general descriptions, to cover most of the cyclones used in mineral separation plants.Cyclones as heavy media separation vessels are discussed by Mark Freberg (this volume). Their use in tailings deslirning is discussed by P.C. Lighthall, eta/. (this volume).Cyclone EquipmentCyclone TerminologyApexObviously, the apex of a cone is the smallest end. However, with cyclones the term is usually used for the fitting which is attached there to control discharge of the underflow stream.Note that the cyclone need not be so mounted that the apex is the lowest point, although that is the most common method. Keeping the apex below the rest of the cyclone helps avoid plugging when the underflow contains very large particles and the tonnage of underflow solids can fluctuate.Various devices for adjusting apex diameter or otherwise controlling the underflow are discussed later under ""Cyclone Construction"".BypassingThe transport of a portion of feed slurry directly to underflow so that classification is bypassed by that portion of feed.This action is fundamental in any hydraulic classification, whether gravity or centrifugal, because the large particles going to underflow have some void volume between them, which remains filled with feed slurry.D50By definition, D50 is that particle size which has an equal probability of going to overflow or to underflow.It is calculated by drawing a curve of recovery vs particle size and noting the size at which 500Jo recovery occurs.This may be done equally with corrected or with gross recovery (see below) and the resulting value should therefore be identified as d50c (corrected d50) or as d500 (gross d50).Note also that it is common in industry practice to plot size analysis data on the retained size rather than on the average of passing and retained (the middle of the size band). To portray sizing alone it makes no difference, but to read a D50 value off a curve of corrected or gross recoveries, it is essential to plot those values on the average size of each band."

Jan 1, 1989

By J. E. Campbell, A. W. Wesner, M. Pobereskin

This paper summarizes the results of an investigation sponsored by The Coates Steel Products Company. The objective was to determine the relative effects of certain chemical and physical properties on the wear resistance of grinding balls when grinding cement. In making this study, a number of types of balls were used in both dry and wet grinding in commercial ball mills. The radioactive-tracer technique was used in separating the test balls from the rest of the mill charge and in sorting the different types of halls that were all tested at the same time for each of the grinding operations. PROCESSING OF GRINDING BALLS In order to determine whether the properties of grinding balls, namely, composition, microstructure and hardness, can be related to the rate of wear, the halls used in this study were selected to represent various combinations of these properties. It was recognized that the mechanism of wear was not the same in the wet mill as in the dry mill. Therefore, the types of balls tested in each of the two environments were not necessarily the same. However, all of the types of balls evaluated in the dry mill were tested simultaneously for one time period, while those evaluated in the wet mill were tested simultaneously for three different time periods. All of the test balls were separated from the charge when the mill was dumped. All of the balls were of 0.940-inch diameter when charged, and all but the regular production balls were finish ground to this size to eliminate the decarburized surface layers. The steels and processing methods used, as well as the micro-structures and hardness levels of the balls, are described as follows: Regular production forged SAE 1095 steel balls were used in both the wet and dry mills. They were forged to a nominal diameter of 0.940 inch and quenched in oil from the forging temperature. Each retained a partially decarburized surface layer from the forging bar stock; the maximum depth of this layer was about 0.030 inch and the decarburization was negligible where the ball was sheared from the bar. The hardness at the surface was 40 to 46 Rock-well C in the partially decarburized area and 57 to 62 Rockwell C in the areas not decarburized. The hardened zone extended to a depth of about one-third of the radius. Below the decarburized layer, the hardened zone consisted primarily of hard as-quenched martensite with varying amounts of retained austenite. This structure changed to fine pearlite at a depth of about one-third of the radius. In order to eliminate the effect of the decarburized layer, a set of production balls of SAE 1095 steel was forged to about a 1-inch diameter, quenched in oil from the forging temperature, and ground on ball-bearing grinding equipment to a 0.940-inch diameter to remove the decarburized layer. The balls' hardened zones were similar to those in the previous set. The hardness of the finished surfaces was 52 to 60 Rockwell C. A slight amount of decarburization apparently remained after the removal of about 0.030 inch from the surface. Balls of this type were tested in the dry mill only. Another set of forged SAE 1095 steel balls of 1-inch diameter was heated to 1500 F and quenched

Jan 1, 1961

By A L. Wills

Cliffs Natural Resources Pty Ltd (Cliffs) operates iron ore mines in the Koolyanobbing region of Western Australia. Ore is mined from three separate hubs and trucked to Koolyanobbing. There it is crushed and screened to lump and fines finished products and railed to Esperance port for export to Asian customers. Cliffs is renowned in the marketplace for its consistent product quality. In 2010, 9 Mt of ore was exported to Asia.Over the last three years, Cliffs has systematically refurbished its product quality system (PQS), to improve efficiency of production while maintaining its high standard of product quality. Particular attention has been given to reducing inventory, which has required significant modifications to the production process design.In redesigning the production process, emphasis was placed on maximising the application of the inherent blending in each of the production process steps and dedicated blending was only introduced where essential. Simulation modelling and statistical analysis of process capabilities were utilised to develop a system that optimises inventory, minimises rehandle, eliminates several decision-making steps and maintains a pull focus throughout the value chain.The new planning functions are now fully integrated and effectively control long-term grade variability rather than relying on long-term stockpiling. The production process design and the daily crusher blend plan are used to control short-term grade variability. With the upgrading of the planning processes the accuracy and consistency of algorithms for lump per cent and lump and fi nes grades became more important and an increased geometallurgical function has been added to the company.The continuous stockpile management system was upgraded to increase the effectiveness of the daily crusher blend planning process and is now the sole intervention point in the production process for grade-based decisions. Grade control systems were modified to utilise advances in software and geostatistics to deliver accurate short range planning models. The reconciliation and sampling systems have also been refurbished with an emphasis on practical application and feedback loops.Accountability and transparency are provided by management reports that are generated from a centralised data warehouse and the introduction of a corrective action system. Standardised reports are available to all stakeholders and a quarterly KPI scorecard assists the management review process.The successful rejuvenation of the PQS has culminated in operational efficiency through the implementation of an integrated end-to-end process flow. Shareholder value is maximised through maximising recovery of the resource and minimising costs. Customer focus is maintained by reliably delivering product with acceptable and low grade variability.

Jul 11, 2011

By C K. McKenzie

As more and more mining operations around the world either switch to, or trial, electronic initiation systems, the breadth of knowledge and experience regarding their effective application has widened considerably.In South America, for example, there is a strong perception that in order to achieve the finest possible fragmentation, very short electronic delays must be used between successive holes within a row. Limited field studies involving measurement of fragmentation have been conducted to support that paradigm and there are few long term studies which have been strongly supported by measurements of productivity either in the pit, in the plant, or in the leaching pads.On the other hand, some well documented studies have been conducted in North America, showing not only the impact of delay timing on fragmentation but also the effect on semi-autogenous grinding (SAG) mill productivity over extended periods of in excess of 12 months. To date, those studies suggest that optimum timing is considerably longer than the times commonly used in South America.This paper explores the current knowledge of the effects of delay timing on issues ranging from size distribution to vibration impacts in pit walls, to vibration and overpressure impacts in surrounding communities. It also explores how fragmentation modelling can be adapted to reflect fragmentation trends that have been reported in various technical conferences around the world.

Nov 8, 2011

By J. S. Whatley

The properties, origin and industrial uses of kaolin clay are briefly reviewed. The general waterwashed beneficiation process is described. Yost aspects of filtration and solids-liquid separation as practiced in the kaolin industry are mentioned along with devices that are currently in the developmental stage. The paper focuses heavily on the well known art of rotary vacuum filtration, including general construction and operating details. Devices under investigation that might be used to mechanically or electrically dewater clay slurries to higher cake solids levels than can be achieved with rotary vacuum filters are described briefly.

Jan 1, 1986

By Fred Delabbio

There are presently several issues that the mining industry is facing, such as underground air quality, deep mining and green house gas emissions, which could be addressed by the application of alternate energies. Several aspects must be considered by the industry in any drive to introduce new technologies within the context of a producing underground mine. This article presents several operational and support aspects that will evaluate the relevance of alternate energies, with emphasis on hydrogen power systems: operational drivers, commercial supply of technology, site supply system requirements, health and safety, capital and operating costs, mine production, corporate philosophy, and role of government. It is concluded that introduction of alternate energy technology requires a step-wise progression: Applicability to the industry, proof of concept testing, development of generic infrastructure, power systems and regulations, whole system studies and detailed studies of cost and risk versus benefits. The current initiative to apply fuel cells is at the proof of concept stage, entering the generic infrastructure stage.

May 1, 2007

By Carl W. Lam

The increased obsolescence rate of electronic products has made it evermore pertinent to understand the potential environmental impact of materials choices to help guide electronic waste (e-waste) management and promote awareness of high burden materials. Methods for screening for the performance of materials and their potential burden on human health and the environment can be used to comparatively select constituents of present and prospective electronic products. These methods should be able to yield more robust information when linked to other decision-making strategies where integrated data on consumer preferences, production quantities, and regulatory initiatives are sparse or unavailable. A framework is presented here for generating metrics of ecological toxicity, human health toxicity (cancer and non-cancer categories) and global resource consumption for evaluating environmental impact of materials (specifically metals) in electronic products. The time-dependent impact trends of United States? printed wiring board (PWB) metals usage, principally derive

Jan 1, 2010

By Sami Makni, Ahmed Bouajila

"To remain competitive in an open market, mining companies are more and more requested to optimise their complex and highly multivariate processes. The increasing amount of process data, brought about by intensive use of instrumentation and the progress in computer data acquisition, enhances the need for more and more powerful and robust tools for the analysis and modelling of the process data. Now, with the emergence of multivariate data analysis (MDA) techniques, on-line clustering of mineral process behaviour is possible and could help in the extraction of valuable process operation indicators. MDA can be used in different mineral processes such as flotation, grinding, smelting etc. In this paper, the focus will be on grinding process as it is the one of the most costly node in the mineral processing scheme (i.e. power consuming) and it is a highly multivariable process. Particularly for primary grinding mills (SAG/AG), more instrumentation outputs and more powerful and significant process indicators are needed for efficient control and optimisation.MDA is a novel approach suitable for understanding mineral process behaviour compared to the traditionally approaches based on empirical and phenomenological modelling. Multivariate techniques can be used for several purposes. In this paper, the following objectives will be addressed:operation diagnosis: Shift differentiation and operation test differentiation can be showed by using MDA tools such as principle component analysis and factorial discriminant analysis.operation performance monitoring: operation regimes can be evaluated by clustering based on an economic criterion performance such as costs, tonnage, product quality, profit, etcIdentification of operation behaviour (monitoring) and selection of drift correction trajectories (control):MDA can be used to identify periods of unusual or abnormal process behaviour and to diagnose, if it is possible, causes for such behavior."

Jan 1, 2003

By P. A. Bepswa

A numerical study done to test the efficacy of heuristics developed for the design of measurement networks for high precision metallurgical accounting is presented in this paper. The heuristics considered were designed to maximise variance reduction of terminal stream measurements through data reconciliation for observable linear flow systems. A complex metallurgical process flow sheet from the mineral sands industry was used as a case study. Monte Carlo type simulations coupled with a non-linear programming based steady state data reconciliation algorithm were used as tools to investigate the heuristics. The results obtained suggested a close correlation between magnitudes of measured variances and the respective levels of variance reduction obtained through data reconciliation for both internal and terminal streams. It was observed that variance reduction through data reconciliation was maximised for terminal stream measurements in networks characterised by high precision measurement of internal streams and/or in flow sheets characterised by high ?stream to node ratios?. Terminal streams attached to highly interconnected parent nodes were observed to experience higher reductions in variance compared to terminal streams attached to less interconnected parent nodes. The results generally highlight the additional benefits of highly interconnected flow sheets and high precision internal stream measurement regimes on the maximisation of variance reduction of terminal stream measurements through data reconciliation. These findings are significant to metallurgical accounting and to process accounting applications in general in that they provide a conceptual basis for design decision making regarding the construction of measurement networks aimed at maximising variance reduction of targeted streams through data reconciliation.

Jan 1, 2014

By S Casas Castellanos

"Tyres consumption is one of the costliest branches of the operation in a truck-based haulage mine. Off-the-road (OTR) tyres working within undesirable conditions have a considerable negative impact on the whole mine’s productivity. Only the rolling resistance due to underinflated tyres could increase truck fuel consumption by 15 per cent. The impact of other conditions such as road surface quality and temperature are difficult to estimate. Tyre management is a demanding activity that requires a high level of coordination between maintenance and production departments.The project is aimed to develop a smart decision tool to assist mine managers to optimise tyre resources. By identifying factors that have significant impact on tyres, managers are able to take timely action to mitigate undesirable working conditions.The proposed model utilises real-time tyre measurement of pressure, temperature, speed, load, deformation and surface profile to report tyre performance in terms of tonne-kilometre-per-hour (TKPH) and tyre longevity. Both indicators are permanently monitored in order to trigger a warning system designed to keep tyres under optimal working conditions.An interactive database ‘Octo-Mine’ wirelessly receives records from a programmable logic controller (PLC) deployed on the truck. PLC records are the integration of multiple sensor signals with a time stamp. Octo-Mine utilises real-time and historical tyre records to generate online performance and longevity reports, as well as preventative and corrective tyre maintenance scheduling, by comparing current tyre status with established standards.To validate the model, the prototype database was populated with hypothetical data to simulate ideal working conditions subject to comparison with real field observations. Additionally, a laser-based technology prototype device successfully measured a new 9 mm tyre tread and a 60 000 km rolled tyre tread in the laboratory.In conclusion, optimal tyre management contributes not only to reduction of tyre waste but also to truck energy efficiency. This project is a first step in proving these benefits under real field conditions. It suggests that further development of sensor equipment and its integration with a communication system is a worthwhile focus for future research.Citation:Casas Castellanos, S, 2016. Optimum Management of Truck Tyres in a Mine, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 212–228 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016