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By T. Hofbauer, M. J. Dry, G. B. Harris, C. W. White

"Urban Mining is a term that is increasingly being used, and represents an appreciable source of secondary materials for the metals extraction industry, a source that does not incur mining costs, but does, at present, incur considerable disposal costs. Electric Arc Furnace Dust (EAFD) is probably the most common of these materials, with an estimated global production of 8 million tonnes annually, of which 1 million tonnes is generated in North America. The contained annual metal value in EAFD at current prices is of the order of $6 billion, yet, apart from the zinc, virtually none of this is recovered.Despite many attempts over the years, with pyrometallurgical, hydrometallurgical or hybrid processes, currently the only commercially viable method of treating these materials is smelting in a Waelz Kiln (or a Rotary Hearth Furnace), which essentially recovers only the zinc, in an impure oxide form, and generates a secondary slag waste, which is still toxic and requires disposal. This paper describes the development of a chloride-based treatment process to recover all components of the EAFD in a marketable form, which centres around the novel hydrochloric acid recovery and recycle operation. Laboratory, miniplant and pilot plant data are presented, leading to the definition of a viable process flowsheet enabling the recovery of pure iron and zinc products (the principal components of EAFD), together with secondary products such as copper, silver, lead, cadmium, magnesium and manganese. A rigorous mass-energy balance is used to examine the preliminary economics involved."

Jan 1, 2014

By Mark Kennedy, Allan MacRae, Cameron Hams

New technology projects, particularly those involving first-of-a-kind metallurgical facilities, have a poor track record of achieving their overall financial targets, as they incorporate technological risks in addition to normal project risks. Traditional project management tools focus on risk from concept development through implementation, but typically fail to address the additional risks associated with a new technology project including slow start-up, slow ramp-up, and failure to achieve design performance (quality or throughput). These additional risks affect future cash flows produced by the project and hence its value, typically measured as net present value (NPV) or internal rate of return (IRR). Common accounting practice is to reduce the present value of future cash flows by applying a chosen discount rate, often reflecting the corporation's cost of capital. This discount rate does not contain an allowance for technological risk, which is often underestimated or misunderstood by both the financial and engineering project managers. This paper will focus on the topic of project risk and new technology, and how these play a role in the probability of achieving the predicted future cash flows. By properly addressing technological risk in the form of risk-weighted returns, marginal projects can be prevented from proceeding, while sound projects can be given the additional time and resources required to achieve the optimal level of front-end-loading (the level which returns the maximum risk-weighted net present value). A simple set of mathematical tools should enable engineers and financial professionals to establish a common level of understanding, thereby leading to a more accurate assessment whether a new technology project is ready to pass through its next level of approvals.

Jan 1, 2011

By I. H. Warren, F. A. Forward, A. Vizsolyi

"Observations are reported on the pressure leaching of material produced by subjecting chalcopyrite to two types of heat treatment. Calcination of the mineral at 825°C, in the absence of oxygen, induces some sulphur loss by volatization, producing a material from which copper can be leached more rapidly than from chalcopyrite. Treatment of the mineral with elemental sulphur at 475°C leads to sulphur uptake accompanied by a change in mineralogical structure of the chalcopyrite. Copper is prefer-entially and rapidly leached from the sulphur-treated material. A tentative explanation of the sulphur-chalcopyrite re-action is presented."

Jan 1, 1968

By Michael J. Rosko

Methods have been developed for processing and analyzing reflected solar radiation data obtained by Landsat 5 Thematic Mapper multispectral scanner. Spatial resolution for the Landsat series satellites is 30 meters per side per pixel. Materials on the Earth?s surface absorb or reflect different parts of the electromagnetic spectrum depending on their physical and chemical properties and, therefore, typically have characteristic spectral ?signatures?. Using these signatures, environmental parameters such as surface water and vegetation may be identified and analyzed. Principal advantages of the satellite image method for environmental monitoring include: a relatively long historic period beginning in 1985 for which information is available, the reliable numerical basis for the results, and the ability to assemble a historic environmental baseline and provide on-going monitoring for large or remote areas where standard monitoring methods may not be practical. However, because the long-term continued operation of Landsat 5 is problematic due to the age of the equipment, QuickBird and IKONOS satellite images were processed to determine if the two systems are sufficiently similar in their results to allow continuing monitoring using QuickBird data. The QuickBird satellite was launched in 2001 and collects the same visible and near infrared spectral bandwidths as Landsat 5, allowing for equivalent process algorithms for QuickBird, IKONOS, and Landsat 5 data. Spatial resolution for the QuickBird images is 2.4 meter per side, allowing for more detailed characterization of the land surface; spatial resolution for the IKONOS images is 4 meter per side. Because of several differences between the satellite systems, including degradation of the Landsat 5 sensor, it is necessary to calibrate QuickBird and IKONOS results to the Landsat results to verify similarity. Recent images from the satellite systems have been processed and results have been compared to determine the validity of comparing Landsat 5 and QuickBird/IKONOS images so that these newer data can be used reliably in the future instead of Landsat 5 data. Results from this comparison are presented in this paper and suggest that analyses for vegetation using the two satellite systems are comparable, and that little calibration is required. Results from comparison of surface water results from the two systems are less comparable and is currently being investigated by the authors.

Oct 1, 2009

By T. R. Madhavan

The development of contact angles on highly polished ?uraninite surfaces, using sodium oleate and dodecyl ammonium acetate as collectors, has been studied at different collector and hydrogen ion concentrations. It was found that sodium oleate in acidic media (up to a neutral: PH) and dodecyl ammonium acetate in neutral and alkaline media give good contact angles. It appears that the combined forms of these collectors, viz., oleic acid and free amine, are more important in effecting contact. W ITH the emergence of uranium as a strategic metal in the last fifteen years, considerable effort has been directed toward the commercial recovery of uranium from its ores. This has resulted in the development of a uranium technology. It is only in recent years, However, that fundamental data regarding the floatability and surface properties of uraninite and ?pitchblende have been elucidated by different methods. Contact-angle measurement is one of the important tools for tl1e evaluation of the conditions of floatability

Jan 1, 1964

By G. A. Vissac

In this paper we intend to deal particularly with the economic side of coal washing as it applies to our mines. We will then discuss why the dry-cleaning process has been selected, and give a brief description of our plant, dwelling only on its specific features and referring the reader to the numerous papers published on the subject for any details on the principles and machinery used in dry cleaning. ECONOMIC DISCUSSION The washery introduces an extra cost for depreciation, operation, and loss in treatment. A certain proportion of the coal, now being sold, and which the miners have been paid for. will have to be wasted. As a whole, the total increase in cost would be approximately 60 cents per ton. On the possibility of recovering this amount depends the success of the washery. There are two advantages to be expected from the washery, the first, which occurs at the mine and which will be certain; the second, more difficult to estimate, because it depends upon convincing our customers that they should pay more for a better product.

Jan 1, 1924

By S. R. Steinacker, H. Schnideritsch, J. Antrekowitsch

Primary copper industry flue dust plays an increasingly important role in the creation of matte and slag. From a thermodynamic point of view, the chemically formed section of fine particles play a techno-logically interesting role in comparison to the mechanical carry-over. Here, the volatilization and the sub-sequent condensation in the off gas system lead to a characteristic distribution of the contained elements which are represented by various compounds of desired metals like zinc and lead. On the contrary, certain undesired components such as arsenic, bismuth and cadmium accumulate within the product as well. This paper describes existing models and theories concerning the formation of flue dust in the copper smelting process and presents a thorough investigation of the physico-chemical fundamentals by verifying assump-tions with thermodynamic calculations. By fully understanding the formation patterns at different stages and temperatures within the process, better knowledge for flue dust in the first step of the pyrometallurgi-cal copper smelting can be obtained - hence leading to new ideas and incentives for the following stages in the copper production cycle.

Jan 1, 2015

By Sudarshan Martins

The measurement of acoustic signals produced by a tumbling mill has been previously used to determine the operating state of the mill and correlate the variations of the sound intensity with the operating conditions of the mill. Separately, the discrete element model (DEM), a software simulation of the mill, was developed to provide insight into the operation of the mill. Presently, there has not been much work reconciling the DEM simulation of the mill with the acoustic signal. Working from basic principles of linear, time-invariant systems, agreement between an acoustic DEM simulation and the measured signal is sought. First, the impulse response function of the mill is measured. The DEM provides the forces applied to the mill shell as a function of time. A convolution of these simulated shell forces and the transfer function gives the simulated acoustic signal. This signal is compared to the measured acoustic signal, both in the time domain and the frequency domain. Finally, a discussion of the results is given.

Jan 1, 2012

By J. S. Redpath

There appears to a definite trend toward the hoisting of greater tonnages from greater depths. There is every indication that this trend will continue and we feel that improvements in the design, fabrication and installation of mine guides will be of significant importance in the future. The present state of the art in mine-shaft guide systems is reviewed and the parameters required for improvement are derived in this paper. Finally, a proposal is made for a new steel guide system which meets the parameters and is economical to fabricate and install.

Jan 1, 1977

By Andreas Zielonka

To meet the increasing demands of the quality and long term stability of technical systems also the applied materials have to full fill higher standards. This is of special importance where the function of a whole system depends on the reliability of the used materials for example for connector systems in automotive, computer and other electronic equipment?s. In most cases for connector systems electro deposited top layers are applied. To improve the quality of the applied layers new electro deposited systems are developed. One important field of research are the development of composite materials as dispersion coatings and multilayer systems. Multilayers are systems with a high number of single inter-layers of different metals or alloys with the wide chance of the alloy composition. As gold is one of the most important contact material for high quality connector systems it is used as basis for the development of multilayer systems. For the electrodeposition of multilayers two different methods can be applied, the single and the dual plating process. As in the dual plating process two different electrolytes are used, the single plating process allows the formation of multilayers from one electrolyte. In the presented research results cobalt and nickel are used besides gold for the formation of the multilayers. The properties of the layers can be influenced in a wide range by the change of electrolyte composition and the process parameters as current density, current waveform, temperature, hydro-dynamic conditions at the electrode surface and by the number and thickness of the inter layers of the deposited materials. The paper describes the fundamentals of the electro deposition of multilayer systems. For the investigation of the properties of the multilayers different techniques are applied. One of the most important parameter are the thickness of the total layer and of the applied sublayers. The thickness of the sublayers can be varied between a few nanometers up to micrometers. The wear resistance, the contact resistance and the plug-in forces are measured as these parameters are important for the technical application of such layers. For the description of the structure composition and surface properties the sample where also investigated by scanning electron microscopy (SEM), energy dispersive x-ray-analyses (EDX) and glow discharge optical spectroscopy (GDOS). The paper shows that the deposition of gold based multilayers is possible and that the properties of such systems can be varied in a wide range what opens new fields of applications of such materials.

Oct 1, 2003

By Jaeheon Lee

"Biooxidation of gold ores or concentrates could be a very attractive alternative to pressure oxidation (POX) or roasting to liberate the gold grains from various sulfides. Crushed heap bioleaching was successful in US and many operations using tank bioleaching of gold concentrate are currently running around the world. Many parameters need to be considered during the project of sulfidic refractory gold ore process. Capital and operation costs are among the most important ones. Run-of-mine heap biooxidation could be very inexpensive and the smaller the crush size (particle size), the more expensive the capital and operating costs for biooxidation application are expected. The capital cost of biooxidation could be a fraction of the cost for building POX plant or roaster and the operating cost could be 1/3 of POX or roasting depending on the method utilized. A new biooxidation process, Sand Farming, is introduced as an alternative to POX and tank biooxidation process. A relatively coarser particle size (P80 = 650 µm) of the process benefits the low cost of grinding against the conventional grinding size (P80 = 75 µm) for other options. The cost of Sand Farming is less than 40% of that of pressure oxidation with comparable gold recovery from the downstream process. This paper will review the laboratory scale testwork for various biooxidation process of sulfidic refractory gold ores and concentrates and provide the economic evaluation showing the biooxidation could be the most economic method without much sacrificing the overall gold recovery. INTRODUCTIONThe decreased availability and lower grade of raw materials has motivated industries to consider recovering values utilizing low cost process options. The process may treat high grade concentrates or submill grade ores that cannot be processed economically by conventional milling-flotation or leaching. Sulfidic refractory gold ores/concentrates have been economically processed by roasting, pressure oxidation, and biooxidation in stirred tank reactor. The process selection is based on a series of studies including multi-year long ore characterization and metallurgical investigations."

Jan 1, 2016

By A. Otsuki

"This paper discusses the primary collector adsorption onto a sulphide mineral in mixed collector systems to understand its adsorption mechanism. UV-vis measurements were performed to identify the primary collector concentration adsorbed on pyrite, and the adsorption kinetics under different conditions were compared to distinguish their difference between single and mixed collector systems. Small amount of secondary collector addition prior to the primary collector addition significantly improved the adsorption kinetics of primary one. The result was explained by the combination of two previously proposed mechanisms (i.e., different adsorption site mechanism and multi-layer product mechanism). This study showed UV-vis measurement as an effective tool to study mixed collector adsorption behaviour.INTRODUCTIONCollectors are surfactants composed of heteropolar molecules with a non-polar and a polar group (Lotter & Bradshaw, 2010). In a froth flotation process, the function of collector is to improve the hydrophobicity of target minerals and selectively float them with the aid of gas bubbles. Because of the chemical or physical attraction between the polar group and the mineral surfaces sites, collector molecules adsorb on the particle surface with the non-polar group assigned towards the bulk solution (i.e., water), thus the mineral particle surface becomes hydrophobic (Wills & Napier-Munn, 2006).Thiol collectors are major collectors widely used in sulphide mineral flotation. Potassium amyl xanthate (PAX), dithiocarbamate (DTC), dithiophosphate (DTP), mecaptobenzothiazole (MBT) are some common thiol collectors. Previous studies reported that some mixed collectors systems enhanced the flotation performance (e.g., Bradshaw, 1997; Bradshaw et al., 1998; Rao & Forssberg, 1997). Thiol collector mixtures are often used in the flotation of sulphide ores, and discussed with the synergistic benefits (Bradshaw et al., 1998) which include lowering the total collector dosage requirements, improving the sulphide recovery and the rate of flotation as well as the improving the froth characteristics. The current paper mainly considered the mixture between two thiol collectors (PAX and DTC, considered as a weaker and selective collector, and stronger and less selective collector, respectively (Bradshaw, 1997)) to further understand their adsorption mechanism that should assist in improving the flotation performance of refractory gold ore."

Jan 1, 2016

By C. Hari Manoj Simha, J. Gholipour, M. J. Worswick

Due to the high pressures involved in the hydroforming process, friction and lubrication play an important role and can affect formability of the material. Tubes of A1Mg3.5Mn aluminum alloy, of 76.2 mm (3 inch) outside diameter and 2-mm thickness were considered in this study. Three kinds of lubricants, Al070, Hydrodraw711 and water, were applied to the tubes and tubes were hydroformed to burst in a square shape die cavity. The key process parameters were recorded during the tests. An in-house Gurson-Tvergaard-Needleman (GTN) damage-based material model, implemented in LS-DYNA, was used to model the process and predict the formability of this material. The applied axial loads and internal pressures recorded during the tests were used in the computations. The effect of different types of elements (solid and shell) with different constitutive models (von Mises and GTN models) in predicting the strain distribution is studied. The GTN damage-based material showed a good ability to capture necking and displacement histories in this process. Both predicted and measured results showed that the lubricant with lower coefficient of friction can effectively increase the comer expansion.

Jan 1, 2006

By R. Khettabi

The mechanical, thermal and bioproperties of titanium alloys allow their wide use in different industries. Compared to aluminum alloys, titanium alloys are very tough, making them that much more difficult to machine than aluminum alloys. Most studies conducted on these types of materials have mainly covered and made comparisons in terms of cutting speed, cutting force and mechanical properties. Recently however, their sustainability and environment parameters have begun to attract significant interest, and it has been found that machining processes generate particles that can be harmful for health and the environment. In this paper, particle emission is investigated during the turning of the titanium Ti6A14V and 6061-T6 aluminum alloys.

Jan 1, 2011

By K. E. Waters, N. Brodusch, R. Gauvin, A. Jordens, Teng. C., H. Demers

Rare earth elements (REEs) become increasingly significant for renewable energy devices and high-technology electronic products because of their large-scale popularity and applications. In this project, a field-emission scanning electron microscope was used to characterize the composition and distribution of REEs-bearing minerals. X-ray elemental maps were acquired with a large area x-ray detector (60 and 80 mm2 collecting area) and annular detector (60 mm2 collecting area), which allow fast x-ray acquisition at high count rate. These elemental maps were transformed into phase maps, which are used to identify the composition of the mineral phases and the REEs distribution over a large area. The phase maps are an easy way to distinguish the phases with and without REEs and compare the efficiency of different REEs extraction processes. Different methods (manual and automatic) for producing phase map were studied by comparing the distribution of REEs obtained from the same area.

Jan 1, 2015

By P. Chu, J. A. Finch

The formation of small bubbles in flotation is usually accomplished by the use of frothers, or sometimes is due to the presence of inorganic salts in the process water. The effective mechanism associated with the presence of these solutes is generally considered to be coalescence inhibition. However, recent work has demonstrated that the presence of frothers and salts also reduces the size of bubble at the initial formation stage. In this paper we adapt the same experimental setup to investigate the time that it takes for a bubble to form; for a known system power input, the energy to form a bubble can then be estimated from the time. The hypothesis is that the presence of frother and salt will reduce the time for a bubble to form, which can be interpreted as an added energy component being derived from the solute. Testing different types and concentrations of frothers and salts, the hypothesis is supported: the mechanical energy required to form a bubble decreases by about 10% in the presence of these solutes.

Jan 1, 2015

By A. Bendada, P. Servais, X. P. Maldague, C. Ibarra-Castanedo, C. Mohr

Infrared (IR) thermography is a nondestructive, non-contact and non-intrusive technique that allows the fast inspection of large and complex structures with limited accessibility. Pulsed thermography is particularly interesting for the inspection of aerospace materials such as composites given that, after submitting the specimen surface to a thermal front, the most common types of subsurface discontinuities (e.g. porosity, de laminations, dis bonds, fiber breakage and inclusions) can be detected with an IR camera as regions showing abnormal temperature patterns. We present first the case of an aircraft door with water ingress and surface repairs on its honey comb structure. We also highlight the advantages and limitations of thermography for the inspection of aircraft composite parts, such as edge flaps, rotor blades and speed breaks. Finally, we expose some results from a Kevlar® non-planar specimen with Teflon® inclusions at different depths and locations.

Jan 1, 2006

By Nigel Saunders, Zhanli Guo

"Quench sensitivity of heat-treatable aluminium alloys is closely related to the precipitation process taking place during quenching. Faster cooling results in less precipitation of coarse phases during cooling, leaving more solutes in the solution before ageing. An alloy in such state would be of greater hardening potential as larger amounts of hardening phases may precipitate out during ageing. Hence, to understand the quench sensitivity of an alloy, it is essential to understand its precipitation process. Precipitation is a diffusion-controlled process and the diffusion is made complicated by the so-called quenched-in vacancies. These vacancies form during solution treatment, become “excess” when temperature goes down, and annihilate during the following cooling and ageing treatments, making diffusion now a function of both temperature and time. This paper first investigates the formation and annihilation of quenched-in vacancies and their effect on diffusion. The diffusion affected by quenched-in vacancies is considered in the kinetic models to realise the calculation of TTT/CCT diagrams for aluminium alloys. The calculated CCT diagrams have been used to explain the observed quench sensitivity and age hardening behaviour of various commercial alloys. The transformation from GP zones to other hardening phases during ageing is also discussed.INTRODUCTION The heat treatment of aluminium alloys mainly consists of three stages: a solution treatment at an elevated temperature, quenching from this solution treatment temperature to room temperature, followed by an ageing treatment to allow the precipitation of strengthening phases(Davis, 1993).The following statements generally describes how quench sensitivity is observed in heat-treatable Al-alloys: faster cooling results in,(i) less precipitation of coarse phases formed at high temperature during cooling, (ii) more solutes kept in solution before ageing, and (iii) larger amounts of hardening phases being formed, i.e. a greater hardening potential. Thus, the quench sensitivity of an alloy is closely related to its precipitation kinetics."

Jan 1, 2018

By Yi-xin Zhoa

The characteristics of coal bumps are analyzed based on the microseismic data from No.8935 workface in Xinzhouyao coal mine, Datong Mining Group. The geology of this workface is characterized by the thick sandstone roof and coal seam, both with relative higher stiffness and strength. In order to investigate the mechanism and precursors of coal bumps occurred in No.8935 workface, the locations of microseismic, the relationship of microseismic energy and frequency and the spectrum of microseismic signals are analyzed. The result shows that the coal bumps in No.8935 workface were mainly induced by the seismic caused by roof failure. The coal pillar near the goaf is more easily to bump. The statistics results indicate that the coal bumps were mainly occurred in the gate road near the pillar, less than 50m ahead of mining face and located in the hard roof adjacent with coal seam. Moreover, the frequency, energy, b-value and frequency spectrogram of microseismic events were found to decrease before coal bumps. It was found that the frequencies of the microseismic events before coal bumps mainly concentrate upon 5~60Hz. The sudden decreasing of frequency and increasing of amplitude of microseismic events can be regarded as a precursor of coal bumps.

Aug 1, 2013

By J. B. Edwards

"The case is presented for the use of simulators for the computer-based training (CBT) of mining plant operators and for introducing them to automatically controlled systems. As well as their use in the classroom, the role of simulators is examined for ""on-plant"" use in trouble-shooting, fault-finding and maintenance of automatic systems. Case studies are presented showing how specific simulators are becoming established or have potential in the areas of automated materials handling, machine testing, setup and guidance. The evolution of scientific simulations into simulators of widespread practical use is discussed and present-day limitations of computer speed and graphics are considered. Related areas of research for the Canadian Centre for Automation and Robotics in Mining (CCARM) are identified.IntroductionCCARM's Commitment to Simulator DevelopmentAs automation is progressively developed and exploited in mining operations, there arises an urgent need to educate and train staff responsible for its introduction and operation in our mines and for its maintenance. For this purpose , an essential ingredient of an automation program is the development of appropriate mining system simulators for use by a wide variety of personnel. The author has been fortunate to have been closely involved with the development of automatic control systems for a variety of mining machines and mining systems in the United Kingdom. A key ingredient of the research phase in each case has been the use of simulation techniques. As projects have moved toward their commissioning and exploitation phase, the simulations have evolved into simulators tailored for use by machine operators and maintenance personnel. Illustrative case studies are presented later. The researach of the newly constituted Canadian Centre for Automation and Robotics in Mining (CCARM) will likewise involve extensive simulation, and the development of simulators (from the scientific programs) for use at the mine by operators and technicians will be given high priority in the Centre's over-all work program."

Jan 1, 1990