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By M. S. Badollet, W. C. Streib

"AbstractA commercial method .has been developed for controlling the texture of chrysotile asbestos fibers so that they may possess properties comparable with natural sem1-harsh fibers for use in wet •processes.The physical properties of the soft, silky and slimy fibers are partially altered by a flash-heating process which removes a portion of the molecular water.The heat-treated fibers show an improvement in filterability, an increase in bulk, absorption, and surface area and better electrical properties, such as volume resistivity.IntroductionCHRYSOTILE ASBESTOS fibers are found in nature having varying degrees of texture, referred to as soft, semi-harsh, and harsh. Fibers of each type of texture have inherent characteristics which directly affect their usefulness to industry. Visual differences are apparent under a microscope where it is seen that the soft-textured fibers have a silky, serpentine or wavy appearance, whereas the harsh-textured fibers are coarser and spicular. Semi-harsh fibers, of course, have properties intermediate between these extremes.Fankuchen and Schneider ( l) have shown by the use of low-angle X-ray scattering that the diameter of the harsh type of chrysotile fiber is somewhat greater than tha of the soft variety. Surface area measurements on various chrysotiles of different textures tend to confirm their findings. By nitrogen adsorption methods, it was found that the surface areas of soft types of chrysotile asbestos are approximately 23M2 / g whereas for the harsh types they are as low as 11M2/g."

Jan 1, 1955

By G. Morin, F. Chiesa, B. Duchesne

The Quality index is a useful tool allowing to assess the metallurgical quality of aluminium AlSiMg foundry alloys (A356/357). Its value is calculated from the ultimate tensile strength and elongation; it increases with the metallurgical quality of the casting, i.e. with finer dendrites, lower microporosity and inclusion count and lower iron content. This Quality index does not depend on the degree of temper applied during the heat treatment (aging time and temperature). After defining the Quality index, it will be explained how it can be predicted from the knowledge of the local solidification conditions obtained from modelling. The paper will then present four case studies of castings for which the prediction of the Quality index by modelling was made. These case studies from different authors will involve the three most common casting processes used for producing high integrity aluminium castings, namely: sand casting, permanent mould casting and investment casting (lost wax). In all cases, the accuracy of the prediction will be assessed by comparing the predicted Quality index distributions to the experimental values based on the published measured values of the local tensile properties.

Jan 1, 2006

By Magdy Ibrahim

This paper presents experimental design and development of a low-cost remote sensing hardware designed to support automated site data acquisition for near real-time progress reporting of construction operations. The developed hardware utilizes open source microcontroller equipped with multiple sensors that include 3D accelerometer, GPS, Data logger and Bluetooth. The use of open source microcontroller makes the developed design cost effective; freeing it from the need for costly license fees. Its platform configuration is flexible; enabling the addition of temperature, weight and other sensors, Wi-Fi and Xbee capabilities to suit individual field applications. Pilot tests have been carried out in laboratory and outdoor environments. The results prove effectiveness and robustness of the developed configuration. The paper provides description of the individual components used in the development of this prototype hardware. It also describes the technical characteristics, capabilities and limitations of the developed hardware. The findings of comparison with alternative technologies used for outdoor tracking of construction operations are presented. The comparison is carried out with respect to range, cost and suitability for outdoor environment. The developed hardware is expected to support a wide range of applications including tracking of earthmoving operations, highway construction and onsite resources. As well, it is expected to enhance safety on construction jobsites.

Aug 1, 2013

By Jan Drzymala, Przemyslaw B. Kowalczuk

Froth flotation is widely used for upgrading of ores and other materials. Efficiency of flotation depends on many parameters, including type, chemical structure and dose of flotation reagents. Selection of a proper frother in flotation depends on the material used, necessary dose of frother and its selectivity. The selectivity of flotation can be characterized by proper separation factors and indices. In this paper separation selectivity and power of frothers were evaluated basing on separation data for a given material and frother, plotted as the recovery of the useful component in the concentrate versus the recovery of the remaining components in the tailing. Such a plot is called the Fuerstenau upgrading curve. The selectivity was defined as the location of the whole upgrading curve in relation to no and ideal separation lines, expressed on the scale from 50 (no separation) to 100% (ideal separation). In turn, the flotation power was defined as the dose of frother to reach a certain upgrading level at which recoveries of the useful and unwanted components are equal. The power and selectivity of frothers were determined for the Kupferschiefer stratiform copper ore floated in the presence of a fixed amount of xanthate and varying doses of frothers using a laboratory flotation machine. Basing on the separation results for different poly(propylene glycol) (CnH2n+1O(C3H6O)mH, CnPm) and poly(ethylene glycol) (CnH2n+1O(C2H4O)mH, CnEm) alkyl ethers, it was found that the concentrate yield and recovery of copper as the useful component in the concentrate were greatly influenced by the type and dose of frother. However, the same results plotted in the form of the Fuerstenau upgrading curve clearly indicated that the selectivity of frothers was similar, while their power was different. It proves that both selectivity and power of frothers are useful parameters for characterizing flotation systems.

Jan 1, 2016

By M. R. MacIver, M. P. Pawlik

"An image analysis method based on chord length distributions is applied to the batch settling of polyacrylamide flocculated kaolin suspensions. Two features of the interaggregate void space, the void chord length distribution mean and the white-to-black distribution ratio are extracted from an image series obtained over the two hour settling experiments. This approach produces three signal values, from two different probability distributions that can be measured as an indication of underlying sediment bed density and aggregation state. Further work is required on the physical interpretation of the signal, the image acquisition conditions, and the parameter selection methods. It is suggested that this chord length based feature extraction technique may be a useful signal to monitor during batch settling or thickening.INTRODUCTIONFew in situ techniques are available that can be used to directly measure aggregate properties within sediment beds in thickeners or secondary settlers. Typical process variables monitored include rake torque and height, bed level and pressure, feed rate and density, underflow rate and density, settling rate, and overflow turbidity; yet these process variables are only weakly related to process dynamics (Concha et al. 2014). Additional process monitoring signals, based on the direct measurement of aggregate properties could improve solid-liquid separation control and allow the extraction of more detailed information from batch settling experiments.Several optical methods exist for measurement of moving suspensions of aggregated solids in the dilute concentration regime, such as focused beam reflectance measurement (Peng and Williams 1994), and the turbidity fluctuation method (Gregory 1985). In the more concentrated region of a thickener, acoustic backscatter penetration and attenuation measured with an acoustic probe and changes in the underlying solid concentration in the highly concentrated, near-bed region of a thickener as a function of height and time (Hunter et al. 2012). While machine vision for froth monitoring has been thoroughly studied with at least five commercialized technologies (Aldrich et al. 2010), its’ application to the study of thickening has been limited."

Jan 1, 2016

By M. J. King, D. A. Van den berg, R. Fukuzawa

"Mercury bearing ore bodies are often treated for the production of copper, lead, zinc, gold, and silver. The mercury deports either to tailings or is collected during various stages of the extraction process. This paper reviews the relationship between various mercury collection processes and the subsequent management of the mercury by-product or waste. It focuses on mercury removal sequestration including cementation, sulphide precipitation, bulk neutralization, and carbon adsorption. Long term mercury management strategies including third-party stabilization, stabilized mercury co-disposal, secure storage, and mercury recycle are also evaluated. INTRODUCTIONMercury is produced in North America as a by-product of non-ferrous metals processing and from recycling of products such as dental amalgam, fluorescent lamps, and thermometers. Its toxicity is recognized to have significant negative impacts on the environment and human health. As a result, many countries are adopting regulations limiting mercury use and its uncontrolled release.The European Union banned mercury exports in 2011 and the United States will do so in 2013. The export bans aim to prevent mercury use in developing countries for activities such as artisanal small scale gold mining. However, by-product mercury production from the non-ferrous metals industries continues.These factors contribute to an oversupply of mercury and the need to find suitable treatment methods for the long term management and storage of mercury and mercury bearing materials."

Jan 1, 2012

By A. M. A. Mohamed, F. H. Samuel, S. Alkahtani

"This article was undertaken to investigate the effect of nickel and zirconium additions on the strength of 354 aluminum cast alloy. The cast alloys were given a solutionizing treatment followed by artificial aging at 190 ºC for 2 hr. High temperature tensile tests were conducted at various temperatures from 25ºC to 300ºC. Optical microscopy and scanning electron microscopy were used to study the microstructure of the samples. The results revealed that the intermetallics phases of (Al,Si)3(Zr,Ti), Al3CuNi and Al9NiFe are the main feature in the microstructures of alloys with Zr and Ni additions. The results also indicated that the tensile strength of alloy decreases with an increase in temperature. The combined addition of 0.2 wt% Zr and 0.2 wt% Ni leads to a 30% increase in the tensile properties at 300ºC compared to the base alloy.INTRODUCTIONThe task of improving the mechanical properties in an aluminum alloy at high temperatures should include the knowledge of several factors which are related principally to a decrease in the strength of the metal with increasing temperatures. This behavior is linked to the change or deterioration in the principal metallurgical parameters of the specific cast aluminum alloy during its performance at higher temperatures. Most of applications of Al-Si casting alloys are generally used at temperatures of no more than 230°C (Lee & Chen, 2002). This recommendation is made in view of the fact that, for certain applications such as those required by the automotive industry, these alloys must operate over a wide range of temperatures and stress conditions where temperatures are liable to rise even higher than 230ºC (Robson & Pragnell, 2003).Aluminum-silicon-copper-magnesium alloys such as the 354 alloys show a greater response to heat treatment as a result of the presence of both Mg and Cu. These alloy types display excellent strength and hardness VALUES (although at some sacrifice of ductility and corrosion resistance. These alloys are used for a wide range of applications, such as engine cooling fans, crankcases, high speed rotating parts, structural aerospace components, air compressor pistons, fuel pumps, compressor cases, timing gears, rocker arms, machine parts, and so forth (Cáceres, Svensson, & Taylor, 2003; Rurrxia, Rong-de, Yu-hua, Cherrxi, Xiao-feng, Heng-rong, & H. Zhuang-qi, 2004)."

Jan 1, 2012

By Kevin J. Melong

"Redpath Canada Limited and joint venture partner Thyssen Mining and Construction Canada have recently completed the sinking of the Scissors Creek service in Saskatchewan through its joint owned company, Associated Mining Construction (AMC). The Scissors Creek service shaft was sunk at Nutrien’s Rocanville mine. The following paper outlines the shaft sinking plant and the methodology related to sinking and shaft lining. KEYWORDS Hydraulic shaft jumbo, Hydraulic shaft mucker, Potash shaft sinking, Shaft lining, Sinking galloway INTRODUCTION The sinking and lining of shafts at mines to access mineral deposits has always been one of the great mining challenges for owners, engineers and contractors. Over the course of history in Canadian mining, the sinking of potash shafts through the notorious Blairmore formation of Saskatchewan has proved to be some of the most challenging shaft sinking projects on record. There is no doubt that today’s shaft sinking business demands the utmost in safety performance while delivering projects within schedule and budget. Given these requisites, Redpath and TMCC (executed under the joint venture company, Associated Mining Construction or AMC), were taxed with developing the shaft sinking system to deliver this program in the safest and cost effective manner, with due regard to schedule and quality. Traditionally the potash shafts sunk in Saskatchewan involved a significant level of manual labour, owing to the methodology of excavation by means of chipping the frozen shaft sections with hand held pneumatic machines, and manually placing tubbing segments or steel liners of the shaft lining system. Most certainly, the AMC team wanted to make a step change from those earlier sinking programs and develop systems for sinking this potash shaft that removed the high level of manual work, thus making this project inherently safer, while endeavoring to sink more efficiently. With that in mind, the team embarked on a design program to improve its overall shaft sinking systems without the requirement for excessive capital and methodology flexibility to adapt to potential changing conditions expected to be encountered during shaft sinking. This was especially important should the new approach be met with less than expected success, and retrofitting of the system was required. The concepts were developed to provide for a much improved work environment, while easing the manual labour burden on the workers with innovative equipment and approach to the work."

Jan 1, 2019

By W. Blum

Progress made in improving the creep resistance of Mg alloys is reviewed with the emphasis on microstructural interpretation. Experimental results on the increase of creep strain with time at constant stress a measured for limited times and strains are displayed in a transparent form as creep rate-strain diagrams from which the minimum creep rate stress is safely derived. In addition, data on the thermal stress component a derived from high-precision a-reduction tests are reported. Within a simple statistical dislocation model these data allow one to quantify the relation between dislocation velocity v and a . In combination with structure evolution laws this relation serves as a basis for modeling the creep rate. New alloys have distinctly higher creep resistance than AZ91 where precipitation hardening plays a minor role. This is due to hardening by intermetallic phases which may form a continuous skeleton along the grain boundaries (e.g. Ca-alloyed AZ91) and/or submicron-sized precipitates within the grains (MRI230D, Mg-Zn-Ca alloys).

Jan 1, 2006

By G. H. Charlewood, J. W. McBean

"One hundred years after being developed, the diamond drill is still an essential tool in mineral exploration. The basic principle is unchanged, but the technique has been revolutionized, particularly in the past fifteen years. The cost of core drilling has not kept pace with the rising cost of living. The price of machinery, supplies and labour in drilling has doubled and trebled since 1946. Some of the techniques which have made it possible to hold the price line are described."

Jan 1, 1967

We report the studies of Proton-Exchange Membrane Fuel Cells (PEM FC) and hydrogen storage materials at McMaster University for the last 14 years. From the initial investigation of ionic conduction mechanism to the revelation of the origin of non-Arrhenius temperature dependence, as well as the synthesis and characterization of high temperature polymer electrolytes, both experimental and theoretical works have been compiled for the fuel cell membranes. In addition to the discovery of suppressed ionic conduction in Electrode-Membrane Assembly (EMA) and novel hydrocarbon PEMs based on micro-emulsion, the first evidence of hydrogen adsorption saturation by carbon nano-tubes was also achieved, which has been the bottleneck for the application of PEM FC. Prior to our study, a number of controversial publications have claimed the hydrogen capacity of these materials to be between 0.1 to 10.0 wt.%, and none demonstrated a plateau of adsorption with pressure that is consistent with monolayer saturation. Others suggested that the tube bundle structure is opened under high pressure to enable higher adsorption on newly uncovered surfaces, but received no confirmation. Using our home made high-pressure instrument with in-situ electrical probes, we found that a plateau is nearly achieved at about 300 atm in the room temperature isotherm, and that nanotube bundles actually compress with pressure instead of splitting, using in-situ electrical measurements.

Jan 1, 2005

By Gerry Doeksen

The paper deals with three case studies: (a) the handling of wet concentrates (5 to 8 per cent moisture) through feed bins; (b) the handling of the same product in rail cars; and (c) the handling of dry concentrates (less than 0.5 per cent moisture) through feed bins. In each case, the paper discusses the problems of rat-holing. In each of cases (a) and (c), there is a discussion on the consequent extreme variations of feed rates coming from the feeders, making automation of process control difficult to impossible. Currently available bin-flow theory and flow property tests are used as aids in redesigning the bins. The paper concludes with illustrations of the final results after the redesigned hoppers were installed and tested. There is also a discussion on the advantages of the new mass-flow bins on adjacent feeder performance.

Jan 1, 1970

By Jan Butra

Longstanding mining of copper deposits in the Legnica-Glogow Mining Basin, Poland has accumulated broad experience concerning the impact of geological and mining conditions on seismic and rockburst hazard. Methods of rockburst prevention for deep copper mines have been developed based on gathered data. Methods of rockburst hazard evaluation and rockburst control constitute a set of rockburst prevention measures. Due to their nature and location within the production process, prevention methods can be passive or active. Active methods of rockburst prevention consist of the liquidation of stresses in the areas where they are concentrated through controlled generation of rock-mass tremors and rockburst by blasting works (group extraction blasting, release blasting in the rock mass and pillars able to accumulate the stress, as well as in the roof and floor). Group blasting works as a basic method are very effective in copper mine conditions. Provocation of dynamic events makes it possible to control the timing of their occurrence. In Polish copper mines, all blasting works are made during the absence of miners in the mining fields. Daily distribution of both the number of recorded strong seismic events and volume of energy released, confirm the advisability of using this kind of rockburst hazard prevention. The rockburst hazard prevention methods developed over 40 years of copper deposit extraction are economically reasonable and offer sufficient effectiveness under high rockburst hazard conditions.

Aug 1, 2013

By Min-Yuan Cheng

Heavy rainfall and typhoon oftentimes cause the collapse of hillslopes across mountain roads. Disastrous consequences of slope collapses necessitate the approach for predicting their occurrences. In practice, slope collapse prediction can be formulated as a deterministic classification problem with two class labels, namely ?collapse? and ?non-collapse?. Nevertheless, due to the criticality and the uncertainty of the problem, evaluating the collapse susceptibility of an area is a challenging task. This study proposes a novel Artificial Intelligence (AI) approach, named as K-Nearest Neighbor Based Bayesian Classifier (KNNBC), to deal with slope collapse assessment. In the proposed model, Bayesian inference is used as a framework to achieve probabilistic prediction of slope collapse. Meanwhile, K-Nearest Neighbor (K-NN) is employed as a density estimation technique. Equipped with probabilistic outputs, the K-NNBC is able to yield predictions with different levels of confidence and diminish misclassified cases. Experimental results point out that the proposed model is very helpful for decision-makers in slope collapse assessment and disaster prevention planning.

Aug 1, 2013

By T. Plikas, L. Gunnewiek

Computational fluid dynamics (CFD) modeling was used to evaluate the performance and optimize the design of a potroom ventilation system in an aluminium smelter facility. The ventilation system must ensure the inflow of fresh air to the workplace by natural draft and the removal of heat and hazardous emissions generated from the pot cell process. A full-scale, three dimensional CFD model of the potroom was developed to predict the air temperature distribution and contaminant concentrations throughout the potroom for the purpose of verifying that the industrial workplace hygiene standards will be met by the proposed ventilation system design. The modeling work was used to optimize the size of the floor gratings around the pot cell and roof ventilator, as well as determine damper settings in the roof ventilator. The effects of outside air temperature and external wind on the performance of the ventilation system was evaluated to ensure the design performs adequately in response to seasonal variations in climatological conditions.

Jan 1, 2006

By H. J. McQueen

The modeling of the extrusion of 6061 alloy and its composites with 10 to 20 vol% Al203 or SiC by two techniques. The uniaxial finite element method FEM (DEFORM" ) provided force-stroke curves and temperature rise over the range 450-500 °C, 2.6-5mm/s and extrusion ratios of 31 and 64. The traditional technique considers ideal work and redundant work as well as friction and uses average temperatures and strain rates. The two techniques are used to clarify each other and to extend the analysis to 400 and 350 °C. The calculated efficiencies are compared to measured values in extrusion trials and to values derived for 7075 extrusion analyses. The analyses are based on constitutive equations determined by torsion testing tests.

Jan 1, 2004

By J. G. Cullain

Inco Limited is an integrated mining, smelting, refining and manufacturing company with operations located worldwide. The Ontario Division operations consist of 13 mines and 10 processing facilities located in Sudbury, Port Colborne and Shebandowan. The scope of our utilization of energy in the Ontario Division in 1976 included in excess of 2.2 billion kilowatt hours of electric power, 12 billion cubic feet of natural gas, 60 million Imperial gallons of residual oil and smaller quantities of other fuels. In addition to the primary energy consumption, waste-heat energy is recovered in various operations throughout the Division, thereby reducing our primary energy requirements. Total expenditures for primary energy alone in 1976 exceeded 60 million dollars. Energy management studies were initiated by Inco's Utilities Department in late 1972, and resulted initially in a program of electric power cost reduction. This program produced significant results by improving the use of the water available for our hydraulic generation facilities and by a comprehensive peak reduction program. Our experience showed that a program of peak power control creates an awareness of both peak and energy costs, and thereby encourages a general reduction in the electric energy consumption as well as lowering the peak demand. Energy management is a continuing program at Inco and, recently, a formal energy management policy and program was instituted. Energy management committees were formed in each plant or mine area to identify the major areas for energy; consumption, thereby isolating areas with large potential energy losses, and determining immediate action which will improve the energy efficiency or reduce the energy waste within their respective areas. A decentralized program with good cross-communication between all committees was felt to be the best method of providing an on-going effective energy management program. In the future, the projections of dwindling fossil-fuel supplies in Canada and the resultant spiralling energy costs will further emphasize the need of sound energy management practices for all Canadian industry.

Jan 1, 1977

By James Stenhouse

Abstract The aqueous oxidation of pyrite in caustic solutions under oxygen pressure was investigated by measuring that effect of reaction variable on oxygen consumption by the reactions. From the results of this investigation, a model for the process has been proposed. In this model, sulphur diffuses as a positive ion through an oxide layer which forms on the sulphide particles and is then oxidized to sulphate ion. Iron is oxidized by substitutional diffusion of oxygen atoms into the oxide layer. The effect of most reaction variables on the rate of oxygen consumption can be explained with this model. Introduction Recent investigations (1,2,3) have shown that certain sulphide ores can be readily leached by agitating the ore in the form of a pulp under pressure in the presence of oxygen. Since very little was known of the mechanism of this oxidation, a programme of investigation was inaugurated in 1949 in the laboratories of the Department of Mining and Metallurgy of the University of British Columbia. Financial support for the investigation was received from the National Research Council in the form of student grants and bursaries, from the Canadian Liquid Air Company, Limited, and from the Consolidated Mining and Smelting Company of Canada, Limited. The first objective was to devise a technique to study the primary oxidation reactions in aqueous solutions and to apply the technique to a detailed study of the oxidation of pyrite in caustic solutions.

Jan 1, 1952

By M. Clotilde Apua, A. F. Mulaba-Bafubiandi

"The efficiency of hydrochloric acid (HCl) leaching of gold from low grade gold-bearing material has been investigated in the presence of sodium hypochlorite (NaOCl) to produce in situ chlorine gas which is an oxidizing agent able to oxidize gold metal to its soluble forms. The effect of concentrations of HCl, NaOCl, and mixtures of HCl + NaOCl was sought. Iron and potassium present in the feed were leached and consumed all the HCl. Gold found as inclusion in pyrite was not exposed to the lixiviant. Therefore, leaching of gold from low grade gold-bearing material in aqueous chlorine solution is not an effective process for now.INTRODUCTIONHydrometallurgy of gold is commonly based on cyanide leaching solution. Due to the environmental concerns related to cyanidation and mercury processes, and inefficiency of cyanide gold leaching to dissolve refractory ores, sustainable alternative lixiviant systems, capable of generating gold (I) and gold (III) complexes must be studied. Amongst non-cyanide gold lixiviants there is the chloride/chlorine system (Hilson and Monhemius, 2006; Senanayake, 2004; Pilsniak and Trochimczuck, 2007; Wang et al., 2007; Reeves et al., 1999; Khodadad et al., 2008).In practice, the most oxidizing agents utilized for the leaching of gold as chloride, are chlorine (Cl2) or hypochlorite (HOCl) which are either generated in situ by suitable reaction or added in solution (Adamson, 1972). The dissolution of gold concentrate using hydrochloric acid, sodium chloride and sodium hypochlorite (Cl-/HOCl system) were studied (Puvada and Murthy, 2006). The effect of NaOCl and NaCl concentrations were also investigated. The leaching was performed under the following conditions; time: 4h, solid–liquid ratio = 1:4, at room temperature. It was found that the increase of the NaOCl concentration from 25 to 75 g/L did not have any meaningful effect on the recovery of gold which was about 30% (experimental conditions; S/L ratio = 1:4, NaCl concentration: 25 g/L, HCl concentration: 0.35 M). It was also found that from 25 g/L to 200 g/L NaCl, the recovery of gold rose from 30% to 40% (experimental conditions; S/L ratio: 1:4, NaOCl concentration: 25 g/L, HCl concentration: 0.35 M)."

Jan 1, 2012

By A. Ghasemi

An alumina-silica coating was deposited on a nickel substrate by sol-gel process, and the structures and composition were evaluated, The sols were made from aluminium and silicon alkoxide, and an acid catalyst including HCl, To produce adherent silica coatings on nickel, various additives such as surfactant, viscose additive and drying control chemical additives were introduced to the system, and appropriate drying and firing cycles were applied after dipping in solution. The hot corrosion and oxidation resistance of the coating at different temperatures were investigated, The structure and uniformity of the coatings were examined by scanning electron microscopy (SEM), The results indicate that a uniform coating of alumina silica can be produced on a nickel substrate by optimizing the composition and process variables of the sol. Coatings can protect substrates from oxidation and hot corrosion at different temperature up to 1000°C, but is not very effective for hot-corrosion resistance at 1000°C.

Jan 1, 2005