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By C. I. Walker

Field tests at a number of large mineral processing operations have been undertaken to better understand the wear life impact of different aspects of pump design, materials of construction and maintenance procedures. Data are presented for wear rates, and typical result variability is explored. To improve the availability of pumping equipment in a milling circuit it is not only important to improve the wear life, but also reduce the variability in the wear life of components so that the incidence of premature failure is lessened. Localised gouging wear due to flow separation and turbulent eddy formation is often the point at which part-holing occurs. A number of improvements to the design of pump impeller and throatbush (suction side liners) to reduce the localised gouging wear are outlined. Also, results are presented on the use of composite materials (mix of metal, rubber and ceramic) for throatbush materials to protect specific areas against wear.

Jan 1, 2012

By Torsten Zeller

Due to the increasing worldwide demand for raw materials and the resulting rise in commodity prices more expensive processing that is able to utilize complex ores becomes economically viable. This and increasing ecological awareness is why the interest in recycling and urban mining is steadily growing in Germany. In addition to that; landfills do also contain elements, which were not targeted over the period, when they were being accumulated. Examples are rare earths, indium, gallium, cadmium, arsenic, selenium and tellurium. Also copper, zinc and lead, the target components of ancient mining, can be obtained due to more effective processing and smelting technologies. Funding by the German Federal Ministry for Education and Research, entitled "r³ ? Strategic Metals and Minerals ? Innovative Technologies for Resource Efficiency" also indicates the high level of strategic interest. It is against this background that the research project "Exploitation of the Raw Material Potential of Mining and Metallurgical Tips in Respect of Sustainability as Exemplified in the West Harz Mountains (ROBEHA)" has been implemented. A major concern of this project is the possible transfer of results to landfills in other areas. Therefore the development of an expert system based on the innovative processing methods and a method manual for urban mining are the central components of the investigation. This will provide an important contribution to the cost optimization of ensuing urban mining projects. To ensure the success of landfill mining projects it is necessary to record the composition and quality of the deposits accurately. Also the environmental impact caused by landfill mining and changes in the natural and cultural landscape will be considered in a multicriteria evaluation method. Depending on their origin the tips are divided into the categories mining, processing, and smelting. The content of a landfill and thus the economic potential in terms of urban mining is dependent on the type and composition of the deposits (host rock, gangue, and ore mineral), the available processing and smelting technology, and the target components at the time of mining. Zinc, for example, was not been processed until the 19th century, when it gained attention as being material of economic importance. After such knowledge about a landfill is obtained the decision for further investigations can be made. For a total of 158 landfills in the Harz Mountains, both the volume and the approximate contents of copper, zinc, and lead has been estimated for the different types of tips within past research projects. Based on the prices of the London Metal Exchange (LME) and a euro/dollar exchange rate of 0.76 (as of 03/05/2012) and assuming a minimum density of ? ? 1.5 t/m³ a average value of 1.6 billion ? in copper, zinc, and lead can be obtained. Although only these three metals are considered in this first estimate, it demonstrates the potential of landfill mining and the need for further research. KEYWORDS Urban Mining,

Aug 1, 2013

By F. L. Wu

Based on the analysis of a sealed coal mine resulting from a fire-triggered explosion, limitations were discovered in the re-entry procedures used to reduce the size of the sealed area that were being applied during the process of re-opening the mine. The analysis of two re-opening plans in a mine using mechanical ventilation showed that the estimation of the degree of damage of two air doors close to the working face with the fire was key to the identification of the optimum mine recovery plan. The operation points of airflow and air pressure of the main fan under either the doors? damaged or intact conditions can be estimated through the use of a ventilation network simulation program. Starting the main fan for a short time period and measuring its operation points of airflow and air pressure allowed their comparison with the simulated values. This procedure provided a reasonable estimation of the degree of damage of the ventilation structures and more confidence in choosing a recovery plan. Through this process, it was possible to conclude that the two doors were still intact. Consequently, the final plan of installing a new main fan in the main decline, sealing the initial upcast shaft and unsealing the auxiliary downcast shaft, was proven to be reasonable at the mine site.

Aug 1, 2013

By E. Quaquero

This article reports on the current state of an ongoing research project which is aimed at implementing intelligent models for hardly predictable hazard scenarios identification in construction sites. As past evidences showed that no programmatic action can deal with the unpredictable nature of many risk dynamics, we tried to survey on how the current approach for safety management in the construction industry could be improved. In our previous research the use of Bayesian networks elicited from subjective knowledge were preliminarily tested. Those networks might be meant as a reliable knowledge map about accident dynamics and they showed that a relevant ratio of occurrences fall in ?hardly predictable hazards? class, which cannot be warded off by programmatic safety measures. This paper reports the second outcome of our research project, which focused on the development of first elementary fragments, regarding the occurrence of a possible ?hardly predictable scenario?. Instead of experts? contributions (who, over their carrier, seldom incurred in accidents), we used ?legal cases? as an accurate source of information. They suggested which categories of ?hidden hazard scenarios? are more likely to happen. We found that the most frequent hidden hazard scenarios are linked to operator?s negligence and abnormal behavior, e.g. irregular removal of scaffolding?s components, unprotected openings, improper use of PPE, etc. Every pattern determined by legal cases has been formalized by a fragment (i.e. elementary network) of the overall Bayesian network. Finally, all the elementary networks were integrated into a comprehensive intelligent tool for realtime hardly predictable hazards prevention. The final setup, asked for interfacing these intelligent models to a low-level sensor network and used to feed them with inputs about the current state of the context, is discussed too.

Aug 1, 2013

By F. Dubuc

"The Adams Mine of Jones & Laughlin Steel Corporation is situated on the Boston Township iron range near Kirkland Lake, Ontario. Eight different orebodies have been outlined, with a total open-pit crude tonnage of. about 100,000,000 tons or the equivalent of 30,000,000 tons of concentrate. The ore consists of fine-grained, well-bedded Early Precambrian iron-formation composed essentially of alternating layers of chert and magnetite. Grade averages about 22 per cent magnetic Fe.The iron range varies in width from 3,000 to 4,000 feet and is made up of several horizons of iron-formation, cherty ""quartzite"" and volcanic rocks. The latter consist mostly of basic lava flows and minor amounts of tuff. Dips are rarely Jess than 50 degrees, and the range is believed to represent an overturned limb of a major synclinal structure. Dykes of syenite and lam prophyre, along with local younger diabase, intrude the rocks of the iron range."

Jan 1, 1966

By Y. Lizotte

"This paper examines the application of blasthole sloping to narrow vein mining in Canada, for ore deposits where widths are less than two metres. While the technique has now been utilized for more than ten years, it remains in the experimental stage and on-site testing is necessary for its adoption at new mining operations or in differ¬ent geological settings. It is intrinsically a safer method than other narrow vein methods in current use.The investigation describes the main operating parameters for mines recently surveyed. The criteria for method applicability are defined and the problems encountered are studied. It is concluded that blasthole sloping for narrow vein mining is a viable modern method which promises to gain popularity and that emerging fragmentation technology and blasting research can be used to further increase applicability of the stoping method."

Jan 1, 1991

By M. Fafard, M. Dupuis, P. Goulet, J. Bédard

Start-up of a Hall-Heroult cell is a delicate task that can affect pot performance and pot life. Modem practices for high amperage cells involve preheating the lining before the molten electrolyte is poured in. Different preheating methods and heat-up schedules are used throughout the industry, and the optimum between a short start-up and damage minimization to the cell is elusive. Direct electrical coke-bed preheating is one of the most common techniques. This practice typically results in a non-uniform surface temperature distribution and can generate detrimental thermal gradients in the cathode blocks. Numerical modeling is an invaluable tool to study this complex problem and can help improve the preheating procedures. The modeling of the mechanical response of the lining is critical to detect risks of cathode block cracking or the development of gaps where liquids could leak into. Taking into account the baking of ramming paste, the quasi-brittle nature of carbon and the contact interfaces between different materials are examples of key elements to consider. A finite element slice model of a cell was built and simulations of different electrical preheating scenarios were performed using the inhouse code FESh++ to demonstrate what can be learned through thermo-chemomechanical modeling. The potential industrial application of the model is discussed.

Jan 1, 2006

By J. McCreedy

"The addition of Portland cement to hydraulic sand fill has resulted in the production of stable and self-supporting cemented sand fill. The use of cemented fill in the mines of The International Nickel Company has resulted in substantial economies in timber requirements, de-creased dilution of ore and greater flexibility in mining methods.Coupled with special mining techniques, it has permit-ted mining by both cut-and-fill and shrinkage stoping methods to much greater depths than heretofore. The use of cemented sand fill has permitted revisions to undercut-and-fill mining which have significantly improved the efficiency of this method.Automated mixing systems have been developed for preparing cemented sand fill in surface sand plants on a continuous throughput basis. Control of cement-sand mixtures is obtained by the use of a mass flow measuring system and weighing cement feeders."

Jan 1, 1966

By M. Greyling, C. Panaou, M. Bellino

Commonly the most frequent method of calculating the overall mass balance of a multi mineral platinum-group metal (PGM) concentrator circuit in Southern Africa has been through the use of spreadsheets, typically Microsoft EXCEL®. While there are some advantages in using spreadsheet based mass balances during the conceptual design phase of the project, their use becomes limited in the detailed design phase of the project. This paper discusses the successful application of METSIM® for mass balancing of a PGM concentrator and highlights the benefits gained during the conceptual and design phase of the project.

Jan 1, 2005

By J. Hendry, K. Brady, J. Yorzyk

Drawing from the experience of nickel, copper, aluminum and mineral borates, this paper illustrates the business value that the mining, minerals and metals industry as a whole can gain from applying life cycle assessment (LCA) to products and operations. Through the use of case studies, the paper explores how companies and industry associations have used LCA to their advantage: from evaluating capital investments, meeting customer information needs, supporting new product applications, and developing credible marketing information on the environmental performance of their products. It also explores the dynamics of LCA adoption and integration within companies, and provides recommendations to further strengthen institutionalization of LCA.

Jan 1, 2010

By A. van As, J. McGaughey, M. J. Mol, R. Tosen

Geotechnical monitoring is a key element of the successful management of a block cave mine. The interrelationships between production and various monitoring datasets are often not realized due to a lack of data integration and appropriate 3D visualization. Timely delivery of information to ensure best cave management practices is only possible with an integrated cave management system. At Rio Tinto, a state-of-the-art cave management system (CaveCAD) has been designed and developed in cooperation with Mira Geoscience to integrate and analyze vast datasets and report this as instructive information regarding the current \u201cstatus\u201d of the cave.

Jan 1, 2014

By A. Zarei-Hanzaki, S. M. Fatemi-Varzaneh, M. Haghshenas

The microstructure in modified semi-solid ALTHIX (A356) alloy consists of aAl phase with Al/Si eutectic structure. Silicon phase in eutectic structure is coral like with fine fibers. The lack of good ductility in this alloy is related to the presence of silicon fibers. Accordingly many investigations have been recently conducted to modify the Si morphology through Thermomechanical processing on this alloy. In the present work an ALTHIX (A356) alloy was deformed at 450°C, 500°C and 540°C through different strain rates. Consequently the silicon fibers were broken into small particles. The results indicated that the Si particles may coarsen according to Ostwald ripening mechanism at 540°C deformed by rate of0.0005 sec-1 & 0.0001 sec-1-

Jan 1, 2006

By W. W. Bake

INTRODUCTION IN IN JUNE, 1943, the main pillars of the Beattie Mine glory hole failed, allowing over a million yards of wet clay and debris to flow into the mine, completely filling all workings to within seventy feet of the 3rd level. The resulting Job of clearing these workings and rehabilitating the mine represents a unique and hazardous operation, seldom, if ever, previously encountered in Canadian mining. The purpose of this paper is to describe one phase of this operation -that of cleaning and rehabilitating the mine from the 6th to the 9th level -to outline briefly the events which led up to this work and to describe the techniques and costs involved. It will be noted that such costs, methods, and performance figures as are dealt with in this paper refer only to work in the internal shaft and adjoining workings from the 6th to the 9th level, previous work having been done under other supervision and management. The Beattie mine is in Duparquet township, northwestern Quebec, twenty miles northwest of the town of Noranda and twenty-three miles southeast of the town of La Sarre. The mine and the town of Duparquet, which it?supports, are accessible by highway from Noranda throughout the year. Production at the Beattie mine began in May, 1933, and up to June, 1943, twenty-one million dollars in gold and silver had been recovered from five and a half million tons of ore.

Jan 1, 1951

By J. R. Giegerich

Purpose It is the purpose of this paper to describe the application of underground conveyor systems to the transportation of ore in the Sullivan mine of The Consolidated Mining and Smelting Company of "Canada, Limited, at Kimberley, British Columbia. General Applications Conveying has been recognized as a means of underground transportation for a great number of years but only during the past fifteen to twenty years has there been any extended application of the method to underground metal-mine operations. Coal miners became conveyor conscious before metal miners. Probably one reason for this is the fact that there are more flat coal seams than flat orebodies. A second reason is that coal is light and is a less abrasive material than most metallic ores. The vast improvements made in belt construction during the past few years, together with improvements in mechanical conveyor equipment, have gone a long way in making this form of transportation attractive to the metal miner. In new mines being opened today, or in major extensions to older mines, the possibilities of conveyor transportation should receive serious consideration. There may not be any widespread application of the belt conveyor as a replacement for the conventional hoisting and locomotive haulage. Where there is an application, tl1e saving in cost can be appreciable and many operating ad-vantages gained because of ease in operation.

Jan 1, 1951

By X. G. Zhao, M. Cai, L. K. Ma, P. F. Li

"Crack initiation stress is one of the characteristic stress thresholds in the rock deformation process under compression. By analyzing AE responses of brittle rocks in uniaxial compression, a new method which is called cumulative AE hit (CAEH) method is proposed for determining the crack initiation stress. An advantage of the CAEH method is that the method removes the user's subjective judgment. To verify the CAEH method, uniaxial compression tests with AE measurement using 77 crystalline rock specimens were conducted. The test specimens cover eight rock classes with different mineral grain distributions. Crack initiation stresses of these specimens were determined by the proposed CAEH method and the LSR method, and the resulting mean crack initiation stresses determined using the two methods were comparable. In addition, taking one rock class with 20 specimens for example, the mean crack initiation stresses determined using the CAEH method and those from several established strain-based and AE-based methods were similar. Hence, the CAEH method can be used as an alternative method for crack initiation stress determination.INTRODUCTIONExperimental observations indicate that the failure process of brittle rocks is associated with crack initiation, crack propagation, crack damage and final strain localization (Brace et al., 1966; Bieniawski, 1967; Lockner, 1993; Wawersik & Fairhurst, 1970). Compression tests on cylindrical specimen are often used to characterize the crack development process. The crack initiation stress (sci), crack damage stress (scd), and peak stress (sc) represent important stress thresholds during the failure process of brittle rocks. Among the three characteristic stress magnitudes, sci is difficult to be determined objectively, directly from examining the stress–strain curves. Some researchers argued that sci obtained from laboratory compression tests is an important parameter for estimating the spalling failure observed in brittle rocks around underground excavations (Andersson et al., 2009; Diederichs, 2007; Martin, 1997). sci can also be used to estimate rock tensile strength and Hoek-Brown failure criterion parameter mi (Cai, 2010). Over the last 40 years, various strain-based methods have been proposed to determine the crack initiation stress in compression tests (Brace et al., 1966; Diederichs, 2007; Eberhardt et al., 1998; Lajtai, 1974; Martin & Chandler, 1994; Stacey, 1981). Nicksiar and Martin (2012) proposed a Lateral Strain Response (LSR) method for establishing sci for low-porosity rocks. Meanwhile, they also used different strain-based methods to evaluate sci of Äspö diorite, and the results showed that all strain-based methods gave acceptable crack initiation stress values. Subsequently, they utilized the LSR method to further investigate the crack initiation stresses in igneous, metamorphic, and sedimentary rocks in compression tests (Nicksiar & Martin, 2013). Compared with previously proposed strain-based methods, an advantage of the LSR method is that it removes the user judgment when interpreting sci. However, the use of the LSR method relies on accurate determination of scd and on having a polynomial fitting equation to find the maximum LSR value."

Jan 1, 2015

By A. Elsayed

Lightweight metals such as magnesium show potential in replacing aluminum alloy castings for engine cradles, cylinder heads and transmission cases. Unfortunately, magnesium alloys are susceptible to entrapping oxides and other impurities during casting that hinder strength and ductility. The current study examined various filter sizes and configurations with the aim of improving the mechanical properties of permanent mould cast AZ91E. The unfiltered casting had a yield strength, tensile strength and ductility of 93.3 MPa, 153.3 MPa and 2.2 % respectively and increased to 96.5 MPa, 167.0 MPa and 3.1 % with the use of a fine mesh filter within the well of the mould. The increased strength and ductility was likely due to the filtered castings containing fewer inclusions on their fracture surfaces as compared to the unfiltered castings.

Jan 1, 2011

By Chris Twigge-Molecey

Demand for metals will continue to grow as global population numbers and prosperity levels steadily increase. Consequently, there will continue to be a need to design and construct new metallurgical plants. Business success in general requires projects to be financially successful and return appropriate value to their owners. However, in the metals industry, private and public sector financing sources have become very sensitive to the perceived inability of projects to contain costs and meet other business objectives. Thus, the capital for projects has become more difficult and expensive to obtain. It is instructive to note that Ernst and Young (2011) identified that: “Delivery of predictable project results bestows competitive advantage and market confidence to those corporations who successfully instill this discipline”. The implication for future projects is that they must be systematically developed to minimize perceived risks—and more importantly—to demonstrate that the risks are managed to achieve the business case. Then, provided that the project has been developed in a well-structured way, project success can again be defined as a project with: a final cost within 10% of the budget approved at the end of FEL3, when the project is properly defined and the permit conditions are agreed upon; a start-up date within three months of the definitive, scheduled startup date; production levels at 85% of design capacity within a year of starting commercial operation; production meeting the target environmental restrictions; and with zero lost time accidents during construction and startup. The plant design is one of many integrated activities required to achieve these objectives. This book represents a valuable link between the existing engineering literature that encompasses a wide range of engineering fundamental textbooks and design manuals and the project management literature such as the Project Management Body of Knowledge, or PMBOK® (Project Management Institute, 2014). It is evident throughout this book, that the design team is a small but essential part of a much larger project team comprising the project management, construction management, and construction contractor staff. Design activities must be regarded and managed as part of the integrated whole, with two fundamental links throughout the design process:

Jan 1, 2015

By Pingyang Zhang, Caichu Xia, Shuwei Zhou, Yu Zhou, Yongsheng Hu

A lined rock cavern (LRC) is an alternative container for compressed air energy storage (CAES) to store high-pressure air that is later used to produce electricity. A critical requirement of CAES in LRCs is that the inner seal should provide adequate sealing capacity to prevent air leakage from LRCs. In many studies, rubber sheets are applied to build the inner seal. However, air leakage through rubber seals has not been given much attention and rubber seals are usually assumed to be absolutely airtight. Given that rubber is permeable especially under high air pressure, such as in CAES, air therefore leaks through rubber seals during CAES operations. In this study, a numerical analysis was conducted based on the permeation equation of polymers and the governing equations of thermodynamics of CAES caverns to analyze the characteristics of air leakage from CAES caverns through rubber seals. A planned CAES plant in China was considered as a case study. Results show that air leakage rate increases with increasing cavern temperature and pressure during air injection and decreases as cavern temperature and pressure decline during air withdrawal. However, in total, the daily air leakage percentage is in the order of magnitude of 10-3% in a typical operation cycle, which is much smaller than the critical value of 1%. Under a common range of realistic operations conditions, the daily air leakage percentage is still of the order of 10-3%. Therefore, rubber seals can be used to prevent air leakage in LRCs for CAES. However, the experience of Japanese pilot cavern indicates that the specifications for the on-site vulcanization jointing and installation methods of rubber seals still need improvement.

Jan 1, 2015

By B. Damjanac, S. Maxwell, D. Chorney, M. Grob, F. Zhang, J. Hazzard

"A hybrid discrete-continuum numerical scheme is developed to study the behavior of hydraulic fractures crossing natural fractures. The fully coupled hybrid scheme utilizes a discrete element model for a core domain, within which the hydraulic fracture propagates and interacts with natural fractures, and a surrounding continuum domain to better approximate boundary effects. The results show that the behavior of hydraulic fractures crossing natural fractures is affected by a combination of factors. Nevertheless, three fundamental crossing scenarios can be identified from all of the simulations: no crossing, partial crossing, and direct crossing. Each crossing scenario has a distinct injection pressure history which may suggest guidelines for interpreting field hydraulic fracture injection data. Additionally, the capability for these models to generate synthetic microseismicity makes them appealing for the integration of microseismic field data with the reservoir geomechanics for ultimately providing a practical engineering tool for improvement of well completion and stimulation. The model is capable of examining and verifying four different shear deformation mechanisms associated with a propagating hydraulic fracture. The natural fracture can fail solely due to the stress perturbation of the passing hydraulic fracture or it can fail due to a combination of stress and pore pressure changes across different types of interaction scenarios. The simulations also illustrate that the level of fracturing complexity increases as the number and extent of the natural fractures increase. INTRODUCTIONAlthough hydraulic fracturing technique has been applied extensively as a reservoir stimulation technique in the oil and gas industry for over 60 years (Economides & Nolte, 2000), it is one of the key factors promoting the shale gas boom in the past decade (King, 2010; International Energy Agency, 2014). The hydraulic fracturing of shales can be differentiated from hydraulic fracturing of conventional reservoirs by the fact that shale formations often have a pre-existing discrete fracture networks which greatly impact the hydraulic fracture propagation. Based upon field production data as well as microseismic observations, it is believed that so called “fracture complexity” may result from interactions between a created hydraulic fracture and pre-existing natural fractures and planes of weakness (Warpinski, 2009; Maxwell & Cipolla, 2011)."

Jan 1, 2015

By T. Takayama Filho

Votorantim Metais Zinco is a smelting facility which produces SHG zinc, zinc alloys, sulfuric acid, liquid SO2, copper sulfate, cadmium metal and silver concentrate. It is located at Juiz de Fora, Minas Gerais State, Brazil. This facility has been operating since 1980 and its current capacity is 95,000 tonnes of zinc per year, using mostly imported sulfide concentrates.The plant uses the conventional roast-leach electrowinning (RLE) process, in which iron is removed from the circuit as jarosite. The residues generated by the RLE process, which amount to about 200 t/day (dry weight), were until 10 years ago, deposited in tailing ponds having no impervious lining. More recently, jarosite and other wastes have been deposited in a properly built reservoir, but this is reaching its maximum capacity. In order to decommission these disposal operations and to reclaim the sites in an environmentally acceptable manner, Votorantim Metais concluded in 2004 a rehabilitation project for the old tailings pond and prepared detailed plans for managing the current and future disposal of jarosite-bearing residues. This paper describes the procedure for removing iron from the hydrometallurgical circuit and discusses the past and current status of the residue disposal sites, as well as the future challenges related to the environmentally acceptable handling of iron residues.

Jan 1, 2006