Search Documents

By H. Pempel, J. Markowski, P. Ay

"Metal-coated thermoplastic parts find more and more functional and aesthetic applications in the interior and exterior of cars. The vapor-deposited or electroplated coatings are usually composed of a plurality of nickel- and chromium-containing layers, which are applied to copper-containing carrier layers on the polymers. Previously, recycling processes are mainly focussed at the recovery or thermal utilization of the plastics. Targeted and selective recycling of the metallic coatings is usually not carried out. Together with several SME, BTU developed a process, in which a complete and separate recovery of all components in high purity is possible with biotechnological methods. The bioleaching is carried out with iron and sulfur-oxidizing bacteria, especially Acidithiobacillus ferrooxidans. The copper-containing layers are dissolved in the solution; chromium- and nickel-containing particles are precipitated as solids. After the bioleaching, a mechanical separation of the individual metal-containing components and their separate workup are carried out. End-products are metallic copper, a nickel- and chromium-containing solid and the cleaned plastics. The bioleaching ensures a high purity of the end products. Through the use of bacteria, which are also found in nature, the process is environmentally friendly. Compared to chemical leaching using inorganic acids, considerably shorter leaching times can be achieved. In addition to the optimization of the leaching process, the R/D-project also includes the development and testing of the apparatus technology.INTRODUCTION The material complexity of many end-user products has increased in recent years, especially in the fields of electrical appliances, vehicle technology and medical technology. However, the demands on functionality, safety, comfort and energy efficiency still play a greater role in product design as factors such as sustainability and usability. For example, if a car still holds more than 70% of steel in the 1980s, a vehicle nowadays includes a larger proportion of a variety of difficultly separable plastics and composite materials, as well as complex metal composites. This relates in particular to composites made from such different materials as metals and plastics. The processing and recovery of the components of those complex material mixtures is difficult for recycling companies."

Jan 1, 2017

By K. Prajapati, P. Hes

Transmission of vibration to the operator from percussive vibrating tools is increasingly of concern in industrial and mining applications. Prolonged exposure to high levels of vibration transmitted via the hand causes disorders known as hand-arm vibration syndrome (HAVS). The vascular component of HAVS is called vibration white finger (VWF) and has a debilitating effect on the hand. Vibration at frequencies below 1250 Hz, a tight hand-grip force and cold environments are reported to increase the likelihood of developing VWF. A vibration damping handle design with patents pending that addresses some of the causes of VWF has been developed and retrofits onto jackleg pneumatic rock drills. The handle is decoupled from the drill while maintaining jackleg twist-grip controls on the hand-grip using a combination of sealed self adjusting hydraulic pistons and compliant materials in series, and a new air control valve. The ergonomics of the hand-grip was also modified by the addition of a polyurethane sleeve with a diameter of 50 mm. The new hand-grip reduces direct cold metal contact and minimizes grip force. Measurement of vibration as the quantity acceleration was made in accordance with international standard ISO 5349. Overall vibration damping in all axes of 50% to 63% was attained at frequencies below 1250 Hz. The dimensions of the damping handle are comparable and its weight is only 100 g heavier than a standard handle.

Jan 1, 2001

By C. G. Anderson

Alkaline sulfide leaching technology (i.e. ASL) has been studied, presented and published throughout the literature and utilized in some current engineering studies. Yet, the actual industrial applications are very few and the knowledge about these is very limited. Hence, a large gap between the laboratory, publications, engineering studies, and the actual industrial plant exists. Recent studies of ASL applied to copper enargite concentrates definitively bear out this dichotomy. Hence, this paper will seek to dispel the common misperceptions that continue to surround the selective industrial ASL hydrometallurgical technology. For edification of the reader, a listing of ten common misconceptions and myths is listed. As well, ASL history, fundamental aspects and a new flowsheet application for simultaneous gold and high purity antimony oxide production from low grade materials is included. The associated estimated economic considerations are also included to heighten enlightenment about the application of this industrially proven technology.

Jan 1, 2014

By A. Vervoort

The concepts of geostatistics are commonly difficult to understand for students, even for those with a strong mathematical background. A main problem is certainly the link between the variation of the parameter value in space or time, and the calculated experimental semivariogram as a function of the interdistance, but over the entire area. Another problem is to differentiate between directional and omnidirectional semivariograms and the way they have to be interpreted. Furthermore first time users of geostatistics often do not want to struggle through different books with the whole geostatistical background before using it. Too often this leads to using geostatistics as a black box with all the risks linked to it. That is the main reason that we developed some interactive tools based on the free public domain software R. We aim by developing three different modules to assist individual first time users, but also regular students and teachers to get a feeling of the importance of the various aspects in conducting a good geostatistical study. The modules show directly e.g. the impact of deleting, moving or adding data points, of changing parameters of the semivariogram model and of the geometrical parameters during kriging. The first module allows making the link between the variation of the parameter values in one direction and the calculated experimental semivariogram, and this for different given datasets. The second module covers two dimensional datasets and apart from calculating the semivariogram values, models can be fitted to the calculated data. A distinction can be made between omni-directional and directional semivariograms, including the effect of the tolerance on the angle and lag-distance. The third module focuses on ordinary kriging of point values in two dimensions. The aim of the interactive tools developed is limited to educational purposes only, i.e. to visualize some basic concepts for different pre-selected types of spatial variation. They do not intend to do a geostatistical study on a certain dataset (for this purpose there exists already a broad spectrum of good software packages). The original intention of developing the three modules was aimed at users with no or a limited amount of geostatistical experience. However, these modules seem also very useful to remain critical for experienced users. One should never forget that in a real application one does not have a complete view of the phenomenon studied. The geostatistical interactive modules can be accessed through: www.bwk.kuleuven.be/geostatistics . We compiled a manual to facilitate the use of the modules and to guide the user we formulated several questions to be solved for each module.

Aug 1, 2013

By S. Haggarty, R. Walton

Barrick's growth and development plan will add three major new mines during 2005 including the Lagunas Norte Project in the La Libertad Province of Peru, the Veladero Project in the San Juan province of Argentina, and the Tulawaka Mine in north¬western Tanzania. Lagunas Norte and Veladero are similar in that they are both green-field open pit deposits at elevations over 4,000 meters above sea level, with two stage crushing and heap leaching followed by Merrill Crowe zinc precipitation for precious metal recovery. Operating sites will each generate in excess of 700,000 ozs Au per annum with commissioning and full scale operation planned during the third and fourth quarter of 2005. Details with regards to regional geography, development schedule, production and process specifics for Lagunas Norte and Veladero will be discussed in this presentation providing an overview for the respective properties.

Jan 1, 2005

By G. C. Bateman

THE cause of silicosis and its prevention have held the attention of medical men and mine operators for many years and at the present rime the study of this disease is more than ever to the fore, even though a considerable abatement in the incidence of silicosis has been noted of late. This abatement is due to individual and collective efforts. The Industry is keenly alive to the situation and much research is being carried on. Silica dust is assumed to be a contributing factor in the cause of silicosis. How it acts progressively in the early silicoric is nor fully understood. As the study advances, more effective measures of control may be evolved. At present the Industry has three known methods of reducing the incidence: 1. By thorough X-ray examination of all applicants, with special reference to chest conditions. Those who are considered to be susceptible to the disease are prevented from entering the industry. 2. Thorough ventilation of the mine. 3. Control of tuberculosis in mining centres and removal of miners when first symptoms of tuberculosis become apparent. In 1934, the Ontario Mining Association formed a Committee, known as the Technical Silicosis Research Committee, to study and supervise work on problems related to silicosis. This Committee obtained the full-rime services of a mining engineer to carry our research work at the mines in the Province of Ontario. The Ontario Mining Association has also provided funds for the purpose of carrying on research work along pathological and biological lines. This work is being done in the Department of Medical Research of the University of Toronto, in the Banting Institute, under the supervision of Sir Frederick Banting. The Silicosis Committee work in full cooperation with the doctors in the Banting Institute and provide material from the mines for the it use.

Jan 1, 1936

"The QEMSCAN system is the third generation of automated mineral analysis systems that began with the QEM*SEM at CSIRO 30 years ago (Butcher et al. 2000). It is now a successful commercial instrument with 39 instruments in operation around the world. Back Scattered Electrons (BSE) and Energy Dispersive (EDS) X-Ray spectra are used to create digital mineral images with mineral identification occurring online. Low-count EDS spectra are used preferentially to BSE brightness, allowing minerals to be accurately identified by chemical composition. Individual minerals or groups of similar compositions are identified by comparison to a comprehensive mineral database incorporated into the QEMSCAN software. Optical mineralogy and Scanning Electron Microscopy is a metallurgists’ tool for determining the ore process mineralogy and delivering a better flowsheet. These techniques have limitations, provide limited information and sometimes fail to provide representative information. In contrast, QEMSCAN provides information on the nature and occurrence of all mineral species present plus the liberation characteristics, looking at thousands of particles in the sample presented. Some of the data presented includes:• Particle and grain sizes• Dominant mineral species• Particle shape• Calculated metal content• Density• Deportment of elements of interest between the mineral phases• Quantitative mineralogy• Mineral associations, locking and liberation• Textural relationships (particle images)It can also be used on concentrates, polished sections or drill core. This is a significant improvement in ore characterisation providing lithology, mineralogy, liberation, ore grade and porosity from a sample. Theoretical grade-recovery curves can be created to be mineralogically limited from QEMSCAN analysis which, when compared with metallurgical results, are valuable in evaluating whether liberation or chemical selectivity is driving flotation performance. A number of case study examples are given where the QEMSCAN had a significant bearing on future project development at an early stage of exploration and mine development."

Jan 1, 2012

By Lloyd W. Trevoy

Titanium and zirconium heavy minerals occur in the tailings streams from processing plants which use the hot-water extraction process for recovery of bitumen from tar sand. In a research program conducted by Syncrude Canada Limited, the crude tailings stream was upgraded to produce quality zircon and titanium mineral products. To process the tailings through conventional upgrading equipment, bitumen residues must first be removed from the mineral grains. Then, by gravity separation, fines and coarse sand grains were removed and a 71% heavy minerals concentrate was prepared which was further separated by high-tension equipment into zircon and titanium minerals concentrates. The zircon concentrate was upgraded by gravity, magnetic and high-tension cleaning to produce a high-quality 98% zircon product. The titanium minerals concentrate was separated into rutile, leucoxene and ilmenite fractions. Heavy minerals distribution in tar sand drilling core samples has been evaluated for various locations on Syncrude Lease 17, and expected annual production levels of heavy minerals have been estimated. A preliminary evaluation has been made of the potential for zircon, leucoxene and rutile production and for further upgrading of ilmenite and leucoxene to synthetic rutile for titanium dioxide pigment production.

Jan 1, 1978

By R. B. Ellestad

Introduction Lithium has been known since 1817, when it was discovered by the Swedish chemist, Arfvedson, while working in the laboratory of Berzelius on the chemical analysis of the mineral petalite, LiAl(Si205)2. Development of the chemistry of lithium proceeded slowly, following the early work of Davy, Gmelin, Bunsen, and Matthiessen. Approximately seventy years elapsed before lithium products assumed any commercial importance, and for a considerable period it was a' very minor industry. Their chief early use seems to have been in medicine, and in the production of lithiated water. Other more important uses were gradually discovered, and the industry has had a slow but steady growth. Chemistry Lithium is classified as an alkali metal, along with sodium, potassium, rubidium, and cæsium. Like these, it is a silvery-white metal, which can be cut with a knife; it is harder than sodium, but softer than lead" It is remarkable in having a density of only 0.53 gram per cubic centimeter, which makes it the lightest metal. On ignition in air, it burns intensely to form chiefly lithium monoxide, Li2O. Like the other alkali metals, lithium reacts vigorously with water to form hydrogen and lithium hydroxide. The later is a strong base, and reacts with acids to form salts. The salts of lithium are in general analogous to those of the -other alkalies, but many of them have unique properties. For example, lithium chloride and bromide are extremely hygroscopic, and have a very high water solubility. Lithium fluoride, phosphate, and carbonate, on the other hand, are all relatively insoluble, unlike the corresponding sodium and potassium compounds. In this instance, lithium exhibits its frequent tendency to resemble the alkaline-earth group of elements (calcium, strontium, and barium). Many of the special and valuable properties of lithium are related to the extremely small size of the lithium ion.

Jan 1, 1948

By S. A. L. Read

"The intact rock constant, mi, is one of the three basic input parameters required for the widelyused Hoek-Brown failure criterion. Values for the constant should ideally be determined by statistical analysis of laboratory test data. In this paper the influence of the inclusion or exclusion of tensile test data on derived values is discussed. We firstly investigate the relationship between direct tensile strength (DTS) test values and Brazilian tensile strength (BTS) test values based on a literature search, finding that the correlation between the two test types is DTS = 0.9*BTS, independent of the lithology being tested. Secondly, using the shear strength database of Douglas (2002), we examine the influence of confining pressure range and the inclusion or exclusion of DTS and BTS test values on calculated values of mi.Chief amongst the influences was the exclusion of tensile data in the calculation procedure, particularly when the Hoek triaxial confining stress range requirement (?3?max = 0.5?c) was not satisfied. Based on a reasonable 1:1 relationship between R (the ratio of unconfined compressive to tensile strength), use of actual tensile data in the calculations for the Hoek brown failure criterion is considered to be a simpler and more robust approach to the use of a tensile cutoff based on empirical criteria such as that of Fairhurst (1964). We advocate the fitting a failure curve using compressive and tensile test data as the most reliable means of calculating mi, while at the same time satisfying requirements as originally advocated by Hoek relating to the appropriate triaxial confining stress range (?3?max = 0.5?c) and sufficient (>5) evenlyspread data points. In the absence of triaxial data the use of R provides a practical means of obtaining estimates of mi that are more robust than guideline values."

Jan 1, 2015

By SANDVIK WHITE

The mining industry produces approximately 4-7% of global greenhouse gas (GHG) emissions. It is fundamental for mining operations to take immediate sustainable action to actively contribute to an emissions-free future for the next generations. The mining industry has traditionally relied heavily on diesel technology and transitioning to more sustainable solutions requires change management to drive cultural acceptance and new product development. Sandvik was interested to find out the lifetime emissions of a single drill rig and to compare similar application diesel and BEV drill rigs with same use profile to each other. That led the calculation and pondering towards comparing different countries and mine sites as well

Jan 1, 2023

By M. Maldonado

This work details the application of a decentralized control strategy to a pilot flotation column working with a two-phase system (water-air). The process is represented by a multivariable system composed of three inputs and three outputs. The selected control variables are the froth depth, the air hold-up and the bias rate, whereas the corresponding manipulated variables are the set-points of the local flow controllers of tailings, air and wash water. All controlled variables are estimated using electrical conductivity based techniques. In particular, the results of a new method for estimating the bias rate, based on the measurement of the volumetric fraction of wash water under the interface, is presented. This method reduces the coupling problem associated to the bias estimation as a difference between feed and tailing water rates. Moreover, the nominal system transfer matrix can be represented by an upper triangular matrix, in such a way that the closed-loop system stability reduces to the stability of the independent control loops. The experimental results show that the closed-loop system performance, particularly that of the bias rate loop, is strongly dependent on the air flow rate, reaching in some cases the saturation point of the controller.

Jan 1, 2007

By C. D. M. Chisholm

IN discussing stope filling, or backfilling, at the Sullivan mine, at Kimberley, B.C., a brief description of the problem will first be presented. The Sullivan orebody is a replacement in quartzite, with the ore con-forming, for the most part, with the bedding. The dip of the vein, apart from local irregularities, averages about 15 degrees near the outcrop in the southwest section of the mine, and steepens to almost 40 degrees at the northeast end of the mine. The thickness varies from a few feet to over 200 feet at the widest sections. The mineable length along the strike has averaged about 4,000 feet between the 4,600 and 3,900 levels-the section under discussion in this paper. To date, 28,000,000 tons of ore have been mined by the room-and-pillar method. Prior to 1930, all ground opened up had been supported by ore pillars, left during mining operations. From that time, the recovery of the ore from these pillars has been given serious consideration. Backfilling, as being carried on today, is the result of this study and is being done for two reasons: (1) to allow extraction of the ore pillars, and (2) to minimize subsidence of the hanging-wall rock, except where forced caving is found desirable. PRELIMINARY DEVELOPMENTS LEADING TO BACKFILLING When the Sullivan orebody was first opened up, early in the century, there appeared to be low-grade sections of the vein sufficient in extent to serve as permanent support for the roof. However, as mining extended into sections of the vein that showed continuous ore over greater areas, wooden cribs, filled with waste and low-grade ore, were erected. In some stopes, these cribs were as large as 40 ft. by 100 ft. in plan and from 50 ft. to 60 ft. in height, but it was soon realized that this method of support was inadequate. As mining progressed, it was found necessary to leave ore pillars, which eventually became the sole system of support. At first, these pillars were left at irregular intervals, but later they were laid out at definite locations on the mine plans, and these locations were adhered to as closely as mining would permit.

Jan 1, 1941

By G. L. Zhu, Y. F. Wu, H. Nagaumi

A novel eutectic-type alloy Al12Si-HTC with high thermal conductivity has been developed by strict chemical composition control and heat treatment. The thermal conductivity of the alloy is about 30 % higher than that of current commercial Al12Si alloy. The Al12Si-HTC alloy has a silicon content of 10~12 wt.%, which provides excellent castability. Trace element strontium or calcium is added to modify eutectic silicon, and contents of transition elements such as copper, manganese are controlled in a low level. By appropriate heat treatment, thermal conductivity of the castings increases by 7.5 % and finally reaches 172 W/(m·K). It is found that eutectic silicon modification which makes average particle size finer than 2µm plays a dominant role in improving thermal conductivity, as well as further spheroidization of eutectic silicon and reduction of lattice defects in a-Al microstructure in subsequent heat treatment process. The alloy is successfully applied to produce a certain communication enclosure with complex finned structure by die casting process in industrial scale. The results of numerical simulation and thermal analysis experiments show that when manufactured by Al12Si-HTC alloy, the surface temperature of chips in the enclosure is reduced by 2.0~4.5 ? and the temperature distribution is more homogeneous compared with traditional Al12Si alloy.

Jan 1, 2015

By M Safa

Addressing deficiencies and defects that occur during construction projects is costly and time consuming. The manual quality assurance programs currently used in the industry have certain limitations, including human error and lack of consistency. Hence, there is a need for integrated electronic models that employ new technologies and methods. This research introduces an integrated construction quality control system that has the potential to improve quality management processes in the construction field for piping construction, which is a complex process often requiring rework. The proposed integrated system relies on data collected from construction sites using photogrammetry and laser scanning, which is then used to compare actual work performed to that designed. The proposed system aims to improve the promptness and accuracy of quality assurance processes, in particular dimension measurements, by avoiding human error and integrating defect detection and quality management. The use of this system has highlighted some of the limitations during data fusion and acquisition process, which are highlighted in this paper. These aspects must be considered to increase the reliability of the acquired information.

Aug 1, 2013

By A. Vasenev

The quality and durability of asphalted roads strongly depends on the final step in the road construction process; the profiling and compaction of the fresh spread asphalt. During compaction machine operators continuously make decisions on how to proceed with the compaction accounting for project specific aspects as: ambient conditions, road geometry, roller type, asphalt mixture characteristics and behavior of other machines. In discussions over quality improvement in road construction it is often suggested to robotize rollers. To operate such robots would of course require operational strategies and routines. The reality of this moment is that these operational strategies and routines are not documented. To identify the existing best working practices and, ultimately, to proceed with developing automated robotized compactors, the knowledge of machine operators should at first be explored and described in a formalized way. Unfortunately operators have difficulty verbalizing their expertise. Observation of behavior, as machine movement patterns, could be helpful to extract the operational strategies, but such observations are time and labor consuming. To overcome this burden we developed a Virtual Reality (VR) environment. In this VR environment operators perform compaction virtually, and their operational choices are traced and analysed. This paper describes this VR development and explains how it helps in following machine operators and extracting their (tacit) professional knowledge. The road geometry and the working conditions are visually represented; the operators show - rather than explain - how they would proceed with the compaction process in the given conditions. Movements of virtual machines are documented, analysed, visualised and discussed. This VR approach is expected to contribute to learning, to more formal description of operational strategies; stepping stones towards compaction algorithms for roller robotisation.

Aug 1, 2013

By L. Price, R. Hortie

Movement of ore and waste from the Hilton Mines pit is accomplished by truck haulage. With the aim of reducing costs, a study of truck fleet replacement was initiated. The study included on-site short-term tests and longer-term rental purchase agreements for haulage trucks. The operation and maintenance characteristics of different trucks, along with projected haulage conditions, were used to prepare cash flows, from which the most advantageous trucks were selected. The results of the study and implementation of the recommendations gave a cost saving greater than had been estimated. The study also indicated areas where improvements could be made, and resulted in much more attention being paid to road conditions, the training of operators and mechanics, and the development of a practical preventative maintenance scheme.

Jan 1, 1971

By E. B. Wright

THE property of Falconbridge Nickel Mines, Limited, is in Falconbridge township, approximately thirteen miles northwest of Sudbury. From the mine and townsite, a gravel road leads to Sudbury and a branch line of the Canadian National railway to Sudbury Junction. The ore deposit is at the southeastern corner of the 'Sudbury Basin'. It lies in a sheet-like mass, striking in an east-west direction, between norite to the north and greenstone to the south. The general attitude of the ore-body is vertical, but with frequent variations in dip of as much as 10° to the north or south. The deposit is very irregular in outline, the width varying from a few feet to eighty or ninety feet. In the vertical plane, rolls are frequently encountered. Gouge is very often present at one or both ore contacts. The norite to the north shows much jointing. The chief ore minerals are pyrrhotite, pentlandite, and chalcopyrite. The nickel content of the ore is usually double the copper content, average assays ranging from 2 to 2.5 per cent nickel and 1 to 1.5 per cent copper. The ore is of three main types: massive, breccia, and disseminated. The breccia ore, the most common type, consists of sulphides containing rounded inclusions of highly-altered country rock, which, in places, are so large that sorting is necessary in the stopes. In the norite, the breccia ore may grade into disseminated sulphides, which frequently are sufficiently concentrated for profitable mining. In places in the breccia ore, concentrations of solid sulphide masses occur. Until early in 1935, all mining at Falconbridge was by shrinkage scoping, but this method was found to be less and less suitable as greater depth was attained. When mining had reached the 1,000-foot level, ore drawn from large shrinkage stopes was found to have been diluted as much as fifty per cent by sloughing of the wall-rocks, caused by increased rock pressure and insufficient support. It was apparent that this method of stoping was un-suitable and -Mr. E. J. Martin was engaged to superintend the introduction of a method of cut-and-fill stoping.

Jan 1, 1938

By D. A. Karvonen

In 1970, the Government of Saskatchewan instituted a program aimed at resolving the dilemma of excess productive capacity over the market demand which existed for potash produced in Saskatchewan. The two primary elements of the program were prorationing of potash production to market demand and a minimum selling price. The paper reviews the factors, both local and international in nature that led to the introduction of the program. The licensing mechanics and the operation of the program, along with the changes that have been introduced in two and one-half years of operation, are discussed. Attention is given to the results of the controls as they affect the industry and the province. Also discussed is the outlook for Saskatchewan potash in world markets.

Jan 1, 1973

By I. I. Bethcherman

Introduction 1.-lmportance of Physical Nature of Condensates The metals of commercial interest which have reasonably high vapour pressures below 1,200° C. are mercury, cadmium, sodium, zinc, magnesium, lithium, and calcium. With the exception of mercury, these metals occupy high positions on the electrochemical series and form compounds with very high negative free-energies of formation. It is highly desirable that such metals should not be produced in a form which is finely divided, on account of their reactivity with atmospheric gases. Powders of magnesium, calcium, and even zinc (blue powder) are dangerous to handle and cannot be coalesced by simple melting techniques. Vaporization in vacuo forms a convenient method of handling and purifying the alkaline earth metals in particular and a previous paper by the authors dealt with some of the factors controlling the separation of metals by this technique (12). An essential part of the operation is the condensation of the vapour to produce a massive deposit which may be conveniently melted and handled by established metallurgical techniques. This investigation sought to determine the conditions affecting the nature of solid condensates.

Jan 1, 1951