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By P. Condori

Palabora Mining Copper (PMC) has two autogenous mills that have been in operation since 1976. The mills were originally designed to treat 30 000 t/d of open cast copper ore in a closed circuit with cyclones. As the ore body went deeper the open cast method of mining was changed to block caving, a consequence of this was the dolerite content (hardest barren material) increased significantly, increasing the production rate of pebbles and thus reducing the milling capacity. In order to cope with the increased ore hardness and to increase mill capacity, a second ball milling stage and pebble crushing were incorporated to the circuit. The above actions created new challenges to the circuit operation and bottlenecks in different areas of the milling circuit. This paper reports the holistic work performed on the Palabora autogenous milling circuit including the implementation of a mill constraint control scheme, the implementation of a pebble removal system from the circuit and a new circuit configuration. The achieved plant stability and increment of ore throughput are also reported in this paper.

Jan 1, 2012

By Pizhi Zhao, Yingdong Li, Hailong Cao, Yingjuan Feng

"Three types of anodic films (unsealed, hot water sealed and agent sealed) were prepared to study the effects of anodizing pores structure on the adhesive bonding performance of AA5754 automotive sheets. The morphology of the anodic films was examined by using scanning electron microscope (SEM) and the composition was examined by glow discharge optical emission spectroscopy (GDOES). The adhesive bonding strength and durability in corrosive environment were investigated by using single lap shear test and salt spray corrosion test (SST), respectively. The results showed that the pores structure could significantly influence the adhesive bonding performance. The unsealed sample showed porous structure and provided high bonding strength, however, the durability was poor in corrosive environment. The hot water sealed sample showed fine and loose hydrated alumin a structure on the surface and provided high durability in corrosive environment, but the bonding strength was low. In contrast, the agent sealed sample provided both high bonding strength and durability in corrosive environment.INTRODUCTIONAdhesively bonded aluminum joints by using adhesives have been widely used for the realization of lightweight design in industrial applications like automotive and aerospace industry[1, 2]. Durable bonds which are capable of taking structural loads can be created due to a careful consideration of the way in which the joint is formed, the type of adhesive and the appropriate treatment of the adherend surfaces prior to bonding[3-6]. Experiences demonstrate that the surface treatment is the most critical step which could not be disregarded, since it is essential to achieve long-term service capability [7].In structural applications, a bonded assembly is expected to maintain a significant load and may be combined with exposure to harsh environmental conditions in its service life. For this purpose, the pretreatment for structural bonding of aluminum alloy must provide not only strong tensile strength and durability but also good corrosion resistance. Chromic acid anodizing (CAA) process provides an anodized layer which has good corrosion resistance while also exhibiting useful adhesion characteristics as well as lacquer coating retaining characteristics[8].However, the use of Cr (VI) is unadvised from a health and environmental point of view since it is toxic and carcinogenic, and this process is gradually limited even prohibited. Boeing's phosphoric acid anodizing(PAA) process provides a more open pore structure allowing penetration of high molecular primers/adhesives[8]and PAA process is the most widely used pre-surface treatment suitable for adhesive bonding between aluminum alloy components. Rahimi et al. demonstrated that nanostructure can be produced by PAA process and is affected by the time of pretreatment and anodizing parameters [9]. Xu et al.investigated the influence of surface energy and roughness on adhesive bonding through PAAprocess and provided improved adhesion performance under certain anodizing parameter[10]. However, PAA process is normally not recommended for a major concern of deterioration of the mechanical performance of the joints as a result of exposure to a wet and corrosive environment. Sulfuric acid anodizing(SAA)process, recently, has been widely used for corrosion protection and good base coating for the adhesion of lacquers in aerospace manufacturing[11]. The good performance is explained by properties such as the porous morphology and high adsorptive power of the oxide film, the chemical and electrical inertness of the anodized layer. Moreover, modified sulfuric acid could also used for adhesive bonding. Lunder et al. found that anodizing in hot sulfuric acid is promising as a simple, very rapid and environmentally friendly pre-treatment for adhesive bonding[12].Saeedikhani et al. studied the process of phosphoric/boric/sulfuric acids anodizing and found it was is a promising pre-treatment for adhesive bon"

Jan 1, 2018

By J. K. Shaw

The science of low temperature engineering is well entrenched in mining. Uses for common cryogens, including liquid oxygen (LOX), liquid nitrogen (LN2), and liquefied natural gas (LNG) in the gas and minerals industries are reviewed. Potential future applications are discussed within the scope of mining, particularly in refrigeration and ventilation. The second part of this paper focuses on the Linde cycle, which is at the heart of most liquefaction plants. Steady state equations describing the mass and energy flows are presented. The paper concludes by explaining the concept of a wind powered Linde- Hampson cryogenic cycle and assessing, with scoping calculations, the technological feasibility of producing cryogens with an intermittent source of (renewable) energy.

Aug 1, 2013

By M. N. Collison

"In 1960, with the opening of the Chisel Lake mine near Snow Lake, Manitoba, the Hudson Bay Mining and Smelting Co., Limited, commenced a new phase in their mining operation -that of bringing ore to Flin Flon over 100 miles of railroad.The schedule of operations required to accomplish this, together with an outline of some of the problems of handling ore at 40° and 50,0 below zero, are discussed. The facilities required to thaw and unload from twenty to fifty cars per working day are also described."

Jan 1, 1966

By J. Duriez, L. Scholtès, F. V. Donzé

"Fracture propagation process in brittle rock is investigated by means of numerical simulations performed with an adapted formulation of the discrete element method. The progressive failure mechanism is simulated through the breaking of the bonds making up the cohesion between the elements constituting the simulated medium. The use of appropriate contact laws associated to a near neighbor interaction feature provide the model the ability to reproduce fundamental characteristics of brittle rock behavior such as, for example, high values of the tensile to compressive strength ratio. Great attention is given to accurately describe the properties of the pre-existing joints or faults in the model. A specific joint model gives the possibility to define a tailor-made behavior of the discontinuity surfaces without suffering from discretization bias.Compression test simulations are performed on pre-flawed samples and compared to experimental results in order to validate the numerical approach for describing the initiation and propagation of fractures in brittle rock under mode I+II loading. It is shown that the crack mechanical parameters can greatly influence the fracturing pattern, in particular its frictional properties. Overall, the numerical simulations reproduce fairly well the failure patterns that are obtained experimentally.The discrete model is then used to study mode I+III loading to give an insight into fracturing problems occurring at the scale of the continental crust. The ability of the model to support mechanically the physical modelings performed with wet clay or sandbox is shown. As an example, the model is used to track the development of a twist crack system (wrench fault) through the nucleation and coalescence of microcracks."

Jan 1, 2015

By D. A. Ainsworth

"The first known use of activated carbon dates back to the Ancient Egyptians who utilized its adsorbent properties for purifying oils and medicinal purposes. Centuries later, the early ocean going vessels stored drinking water in wooden barrels, the inside of which had been charred. (However, by modern definition the carbon used in these applications could not truly be described as activated.) By the early 19th century, both wood and bone charcoal was in large scale use for the decolorization and purification of cane sugar.However, it was not until the beginning of the First World War that the potential of activated carbon was really capitalized upon. The advent of gas warfare necessitated the development of suitable respiratory devices for personnel protection. Granular activated carbon was used to this end as, indeed, it still is today.By the late 1930's there was considerable industrial scale use of carbon for both gaseous and liquid phase application and new manufacturing processes had been developed to satisfy the needs of industry. During the 1939-1945 war, a further significant development took place - the production of more sophisticated chemically impregnated carbon for the removal of both war and nerve gases."

Jan 1, 1984

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 P. H. Agson Gani, T. Sitorus, N. P. Widodo

"PT ANTAM UBPE Pongkor underground mine use blasting to develop its tunnels which will cause poisonous and dangerous gases trapped inside mine. To analyze this case, a study of mine ventilation, the dispersion of carbon monoxide (CO) gas concentration and diffusion coefficient is commenced. At the end, the re-entry time formula will be determined. Results indicate that this study is site specific and could only be applied in the place this study executed. The aim of this study is to be further developed by applying Principal Component Analysis (PCA) to find a universal re-entry formula. KEYWORDS Mine Ventilation, Re-Entry, Smoke Clearing, Diffusion Coefficient, Carbon Monoxide Gas, Gas Dispersion INTRODUCTION Pongkor underground mine is using cut and fill as its mining method. Thus, its development and production processes require blasting to develop its tunnel. This process caused poisonous and dangerous gases spread and trapped inside the mine, one of them is carbon monoxide (CO) gas. CO is formed in an unbalanced reaction of explosives detonation and could be the cause of headache, blackout and death to people who inhale CO at certain concentration (McPherson, 2011; Hartman, Mutmansky, Ramani, & Wang, 2012). Mine ventilation system is installed in the mine to resolve this problem. Mine ventilation play an important role to disperse CO gas by absorb the poisonous/dangerous gases and deliver clean air into mine. The important parameter is diffusion coefficient, because diffusion is affecting particulates or gasses spreading from its sources throughout the mine. Diffusion coefficient is the total diffusion in axial direction of turbulent flow mainly by convection of bulk motion, advection and eddy diffusion, while the effect of molecular diffusion is appreciably negligible (Widiatmojo et al, 2015). Taylor (1953, 1954) develops a theory about the dispersion by inducing a slow stream of solvent into a capillary tube. Taylor used Reynolds assumption of radial diffusivity to be analogous with the transfer of the matter in turbulent flow as well as the transfer of momentum and heat. Then, Taylor proposed the formula of diffusion coefficient, D (m2/s), against pipe diameter and turbulent shear velocity are as follow:"

Jan 1, 2019

By H. G. Wang

The production process of a coal mine can often be interrupted by all kinds of events scheduled or unscheduled and thus often needs gas drainage for a temporary or long-term sealed area. Gas drainage has a relatively high risk, therefore attention must be paid to its design to keep the process safe. Based on the conservation laws of mass and constituents, and under the conditions of the allowable gas concentration limit in the return air route, the relationship between gas concentration and gas drainage flow rate as a function of time during the drainage process is discussed in detail to build a mathematical model of gas drainage from a sealed area. With respect to the gas drainage process, two different conditions need to be considered: one with a methane free fresh air supply, the other with a low gas concentration. This paper presents the derived mathematical models for these situations and then shows that they can be incorporated into one model with some modification. This combined model can be employed to determine the optimum gas drainage flow rate with the shortest drainage time. The application is coded using the C# programming language within the .NET framework. Finally, the application program developed by the author is used to validate the mathematical model through an example of gas drainage with varying rate.

Aug 1, 2013

By C. Fortin

The subject of gold flotation has been reviewed extensively in a number of publications. The focus in most of these reviews has been on the theories of gold flotation as well as the physical and chemical effects that may impact the efficacy of the gold flotation process. It is evident that the current status of gold flotation chemistry as it is being applied in industry has not been addressed widely. It is the intent of this paper to review current gold flotation practice and how these applications tie in with the current understanding of the chemistry of gold flotation.

Jan 1, 2011

By C. S. Crocker

The Centennial orebody was discovered and named in 1970, Manitoba's centennial year. It is relatively small, about 2 million tons. Strike length varies from 400 to 600 feet and widths from 10 to 60 feet; dip is 75 degrees. Low grade and metal prices demanded low-cost mining, and the mine was developed for conventional sublevel stoping. As the ore lay entirely under a large lake, ground movement had to be avoided and the stopes were to be filled hydraulically. Late in 1973, vertical crater retreat mining was introduced at Inco Limited, Sudbury, to recover pillars between filled stopes. It proved satisfactory and the results were publicized by CIL, who developed the technique. The method seemed to offer some advantages and one stope at Centennial Mine was selected to be mined by VCR while production was maintained from blasthole stopes. The trial stope was safe and showed lower development costs, reduced drilling time, a favourable powder factor and good fragmentation. VCR mining is now an accepted method at HBM&S Co., Ltd., and its use is being extended.

Jan 1, 1979

By L. Henry Smith, David C. Arthur

"The Williams Mine is Canada’s largest gold producer, with annual production of 450 000ounces from 2 300 000 tonnes of ore. Highly mechanized and automated underground mining practices are employed in order to achieve and maintain high levels of productivity and minimize costs.The mine ventilation system is modified to include a new vent raise and variable pitchvane-axial fan. This addition allows several fan installations underground to be decommissioned. A substantial net savings in installed horse power is achieved.Heating costs associated with under-ground ventilation air are a significant portion of mine operating costs. Air heating costs are substantially reduced by recovering heat from upcast exhaust air, minewater and compressor cooling circuits. This waste heat is used to supplement propane fired air heating systems for underground ventilation air. An additional benefit is the availability of a heat sink for summer cooling of the compressors.System design, energy savings data and payback calculations are presented."

Jan 1, 1996

By T. H. Adair

"IntroductionCONTINUOUS casting of ferrous and non-ferrous metals is not a new innovation. Patents describing machines for continuous casting are on file as far back as the year 1842. In the middle of the last century, Sir Henry Bessemer conceived and built a continuous casting• machine for the production of mild steel sheet.The production of billets and slabs of both non-ferrous and ferrous metals is being carried out by the continuous method on a fairly large scale on this continent and abroad. At present, the volume of production of •copper and aluminum and their alloys in billet and slab form is much greater than the continuous casting of steel products. The new installation of a continuous casting unit at Atlas Steels, Limited, is designed primarily for the casting of alloy steel billets and slabs.As an introduction to the art of continuous .casting of metals, it is interesting to examine a few of the many devices which have been developed. As previously mentioned, Sir Henry Bessemer constructed a machine for the direct casting of mild steel sheet. His discoveries and ideas of continuously casting steel formed the foundation for the work of other pioneers in this field, all of whom have contributed to the improvement of this art through the ensuing years. The machines which will be selected for examination are those of Bessemer, Poland-Lindner, Williams, Ennor, and Junghans. The last unit to be discussed will be a modification of the Junghans machine recently installed at Atlas Steels."

Jan 1, 1954

By A. Boeing

Rock-breaker automation and remote operation improves the safety and efficiency of mining operations. This article presents an overview of the Rocklogic rock-breaker automation system architecture that provides collision avoidance, automated parking, and remote operation functionality. The system consists of a distributed computer control system that interfaces with sensors attached to the rock-breaker, the rock-breaker hydraulics, and the site infrastructure. We present results of an automated Transmin rockbreaker installed in a production environment at an underground Australian mine site. The system has been in production use for over 900 days during which there have been no reported collisions, and 100% adoption of the remote operation technology. As a result, Rocklogic has significantly improved the safety of rock-breaking operations and reduced the rock-breaking cycle time, thereby improving the sites overall throughput.

Aug 1, 2013

By W. J. D. Stone

"For several years, the existence of a deposit of barite (BaS04) near Brookfield, Nova Scotia, has been known. A very large deposit of strontium (SrS04) near Sydney, Cape Breton, is a more recent discovery. Cape Chemical Syndicate has been formed to work the deposits. A five-million-dollar integrated mineral processing and chemical plant is planned for Sydney to produce various compounds of barium and strontium. The mineral processing plant includes the Jones Wet Magnetic Separator and will produce high-purity barite and celestite. These products will be processed further in the fine grinding plant and the chemical plant. The general project is described, covering the deposits, processing and markets."

Jan 1, 1969

By J. D. Aitken

"DEFINITION OF THE REGIONTHE REGION considered in this paper is bounded on the south by the 60th parallel, on the north by the Beau-fort Sea and Amundsen Gulf, on the east by Archean rocks or by highly deformed Proterozoic rocks of the Canadian Shield (certain weakly deformed Proterozoic strata being regarded as belonging to the Great Plains), and on the west mainly by the Mackenzie and Richardson Mountains.Only the unmetamorphosed strata of the region are considered; that is, the geology of the crystalline basement is ignored.SIGNIFICANCE OF THE REGIONThe region is significant from three points of view -namely, the economic, the scientific and the social. It constitutes 46 per cent of the area of the Western Canada Sedimentary Basin."

Jan 1, 1970

By D. J. Reddish

The paper describes a case study where numerical modelling has been applied to predict potential risks associated with inflows of water in active mine workings from an overlying sandstone aquifer. The objective of the modelling was to predict the development of strata fractures and strains as the longwall panels were extracted and investigate their relationship to an sandstone aquifer. The numerical modelling study also included the investigation of the effect of mining on a fault that existed close to the start position of one of the panels. The potential effects of mining on the fault were undertaken by parametric studies adjusting properties for the fault and the relative position of extractions, which allowed the mine planner to position the panel layout accordingly.

May 1, 2003

By D. Letzig

Wrought magnesium alloys are of special interest as lightweight structural components as a result of their more homogeneous microstructures and improved mechanical properties compared to cast components. Extrusion as a shaping technology offers the possibility to produce a wide variety of magnesium alloy profiles. In this contribution we describe the role of extrusion parameters such as extrusion speed, ratio and temperature as well as the type of extrusion process on the microstructural development of AZ-series magnesium alloys and the resulting mechanical properties. The effect of microstructure on the tensile/compression deformation behavior of the alloys has also been investigated. Aspects of process optimization designed to overcome technical and economic limitations and thus establish magnesium alloy profiles for industrial applications will also be discussed.

Jan 1, 2006

By D. M. Maijer, S. L. Cockcroft, S. Modak, A. B. Phillion

"A comparison between hydrogen-diffusion-based micro-porosity formation and growth behaviour of two important aluminium foundry alloys, B206 (Al-Cu) and A356 (Al-Si-Mg) is presented in this paper. Specifically, the predicted pore size and pore fraction distribution of these two alloys resulting from directional solidification and identical hydrogen concentration are investigated numerically based on a model proposed by Yao et al. (2011. Met. & Mat. Tran. A. 42A, 4137–4148). This model takes into consideration the initial hydrogen content in the melt, the cooling rate, the partitioning of hydrogen between the solid and liquid phases, and the evolution in solid fraction with temperature. Due to different alloy chemistries, the activity of hydrogen in B206 and A356 are quite different, as are the solidification range and the resulting solidification microstructure. Being a primary alloy, B206 has dendritic microstructure and solidifies over nearly 135°C (505–641°C), whereas A356 contains fifty percent eutectic microstructure, and solidifies over 80°C (533–613°C). This allows a very different behaviour of micropores i.e. the effective pore radius in B206 is quite a bit lower as compared to A356, as is the pore number density. The evolution of local hydrogen concentration in liquid metal is analysed and compared for both the alloys.INTRODUCTION Over the past decades, the demand for materials with enhanced strength-to-weight ratios has significantly increased in the aerospace and automobile industries in order to improved fuel efficiency. For many automotive components, particularly shape castings, the trend is towards replacing ferrous alloys with aluminium alloys. The increase in the use of Al is primarily due to its low density, about one-third that of steel, and its relatively good strength that allows for weight reduction without reducing performance. Presently, Al-Si based alloys (e.g. A356) are the most prevalent due to their good mechanical performance in strength-to-weight ratio and excellent castability (Atwood et.al., 2000). However, superior mechanical properties can be achieved using Al-Cu alloys. For example, the alloy B206 offers a higher strength while retaining excellent ductility (Poirier et.al., 1987)."

Jan 1, 2017

By Kai Zhang, Aijun Huang, Jeremy H. Rao, Xinhua Wu, Paul Rometsch

"As one of the most typical additive manufacturing (AM) technologies, selective laser melting (SLM) removes many of the shape restrictions that limit materials design, thereby allowing computationally optimised and high performance structures to be directly produced and tested. Due to the high reflectivity and lower absorptivity of Al alloy A357 powder during high temperature laser melting, one of the issues SLM might bring is the surface roughness and defects present on the parts. In this regard, this study investigates the surface roughness – fatigue property relationship for a heat-treated aluminium alloy A357 after SLM. Via the adjustment of SLM parameters, an ultrafine microstructure can be obtained due to the fast solidification rate. Therefore, comparable or even better mechanical properties can be achieved with respect to traditional A357 casting counterparts. Meanwhile, the surface roughness conditions of the SLMed Al alloy are also influenced by various processing parameters, raw powder properties, and sample building methods. For selective laser melted Al alloy A357 specimens, a dense part with a smoother surface would be expected to correspond with a good fatigue performance.INTRODUCTION Additive Manufacturing (AM), also known as 3D printing, is a process in which a complex part is fabricated layer by layer from a digital design package (Martin et al., 2017). AM has the potential to conserve raw materials, reduce the energy consumption, part cost, and fabrication time. Furthermore, as a typical additive manufacturing (AM) process, selective laser melting (SLM) was originally developed from selective laser sintering (SLS) based on higher quality lasers (Rao, Zhang, Fang, Chen, Wu, & Davies, 2017b). Different from conventional casting consuming valuable time and energy, SLM is now used as a cost effective method for the manufacturing of metals, such as Al-Si alloys, to produce almost full density parts using fine metallic powder and high power laser beam (Tang & Pistorius, 2017)."

Jan 1, 2018