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By D. M. Watson

Mineral discoveries and subsequent extraction have led to the establishment of many small communities, some major towns and a few cities . In Canada, such developments have essentially occurred without benefit of long-range regional or local planning. In the past, this was not a cause for concern. Now, however, rising expectations and reorientation of social values have placed increasing responsibility on government and industry to ensure the long-term viability of communities and regions. Such responsibility means large investments by government in infrastructure and by industry in extractive and processing plants. Uncertainty in the interpretation of ore reserve estimates becomes a critical factor. The traditional methods of reporting reserves - "proven", "probable" , "possible" - may be useful in individual mine production planning, but they are inadequate for planning industrial and public infrastructure, The need for a better information base is critical, with clear and precise definitions of what is being reported, but we are a long way from achieving it. The challenge is therefore to develop a closer professional relationship between government and industry and to tie mineral development to long-range regional strategies.

Jan 1, 1977

By Michael L. Free, Shukla. Abhijeet

The short-circuiting tendency of a copper electrowinning cell (EW) based on the roughness of cathode deposits was investigated with varying parameters such as Cu concentration, guar concentration, current density, and temperature. A bench scale EW cell was set up to produce copper under conditions similar to industrial Cu EW. In addition, a statistical analysis and finite element analysis were performed to analyze the deposited thickness, surface roughness and maximum feature height. Interaction data for the cathode deposits suggest that current density and Cu concentration together affect the roughness of deposit more than the combined effect of guar and temperature. Model predictions of roughness were similar to experimental values. The predicted time to short-circuiting was similar to the measured time. This study provides an industrial relevant baseline against which new operating parameters can be compared.

Jan 1, 2014

By D. P. Wilkinson

Flow field design is critical to determining fuel cell performance with respect to operating conditions. Flow fields are normally designed around their maximum power operating point with the goals of maximizing performance and minimizing pressure drop between the inlet and outlet of the flow field. At lower power pressure drop is reduced, and water management and reactant distribution issues can occur over the active area as well as issues with cell to cell reactant distribution in the fuel cell stack. Flow fields have fixed flow channel geometries and fixed active areas which determine the reactant flow characteristics over the operational range of the fuel cell. In this paper we discuss some of the benefits of a new approach of changing the flow field active area with changing operating conditions. Such benefits for future fuel cell designs could include improved cell performance and stability, improved cell to cell reactant distribution, reduced low current density failure modes, and overall system advantages.

Jan 1, 2005

By M. P. Rennick, D. M. Burton

Abstract -The Murray Brook massive sulfide deposit, which was the first geochemical discovery in the Bathurst camp, is one of the largest sulfide deposits in the area. The massive sulfides are hosted by quartzose metasedimentary rocks in the lower part of the Ordovician Tetagouche Group. This thick succession of sedimentary rocks is overlain conformably by felsic volcanic rocks, and is structurally overlain by mafic volcanic rocks. The massive-sulfide body is polydeformed, but primary metal zoning is still discernable and may permit future exploitation of discrete lead-zinc and copper zones. Although it was discovered in 1956, the deposit was not developed unti11989, when Murray Brook Resources commenced processing of gossan containing precious metals. Recovery of gold, silver, and mercury is accomplished by indoor vat leaching on a year-round basis.

Jan 1, 1992

By H. Houali

Corrosion is an electrochemical process that causes degradation and deterioration of various steel works (pipelines, drains, cisterns) whether they are buried, immersed, or not. Worldwide, we estimate that corrosion destroys a quarter of the annual production of steel at a rate of 5 tons per second. Several techniques are used to protect against corrosion. Among these processes, Cathodic protection, which is regarded as the best technique to assure the protection of steel, works against this phenomenon. This is achieved either by a system of reactive anodes, or by the technique of impressed current protection or other techniques. Before any installation of cathodic protection, a preliminary study and pre-evaluation of certain parameters must be made. In the present work, we will present an example of dimensioning of an installation of cathodic protection by imposed current of a pipeline using solar energy, where we discuss the following items: ? Evolutions of the potential as well as current along the pipeline and their respective expressions deduced from the laws known as telegraphists; ? Range of protection (potential of protection along the pipeline); ? Influence of the isolation resistance of the coating on the range of protection; Effect of the aging of the coating and its influence on the current of protection

Jan 1, 2005

By R. Kamguem

The surface of a mechanical part plays an important role in determining performance in service. The presence of scratches left by the cutting or tearing of the material on the surface of the workpiece supports the concentration of stress and strain. This article presents the experimental study for high speed milling of the aluminum alloy 7075-T6, using cutting tools different by the nose radius and coatings (TiCN, TiAIN, TiCN + A12O3 + TiN). A multi levels factorial design of experiment (DOE) and statistical analysis was used. The roughness parameters investigated are Ra, Ra, Rv, Rc, Rsm, and Rk. The results show that the feed rate, the types of coatings and the geometry of the cutting tools have the most significant impact on the surface roughness profil. Surface finish charts according to feeds and cutting speeds were established for each tool tested.

Jan 1, 2011

By Mihaita Matei

An adaptive approach to control the deformation in tube hydroforming process is presented. This requires: the use of an existing non-linear FE software (ABAQUS) that incorporates a user material model (VUMAT), the development and implementation of an adaptive control strategy to coordinate the internal pressure and the axial load so as to prevent fracture and wrinkling failures (knowledge-base controller) and the application of the developed adaptive simulation approach for finding the optimal loading path required to hydroform a defect-free part with as uniform thickness distribution as possible (user's load subroutine (VDLOAD). In order to validate the approach, the case of conical hydroforming and the case of bending followed by hydroforming component is discussed.

Jan 1, 2011

By Fulchand Shende

Around the world many potash mines experience brine inflow problems. The presence of brine in underground excavations may induce structural and stability problems. A study has been carried out to simulate the effect of brine on the performance of pillar support. The testing program consisted of loading potash specimens in a creep frame, and simulating inflows by continuously pumping brine into an experimental cell. Brine temperatures and load conditions were varied to simulate several mining and inflow conditions. Specimens were fitted with acoustic emission transducers to monitor energy emissions during an eight-hour test duration. Samples of brine were also collected to provide K+ and Na+ concentration data necessary for an accurate assessment of the dissolution process. Test results indicated that dissolution rates are highly dependent on brine temperature and load conditions. Loads approaching 50% UCS tend to generate very high rates of energy emissions, often leading to the failure of the simulated pillars. This study demonstrated that acoustic emission could be effectively used for predicting the performance of pillars when exposed to inflow brine.

May 1, 2001

By D. F. Machuca-Mory

The new algorithm for high-order simulation of ore deposit grades termed HOSIM is based on the concept of spatial cumulants. The algorithm is tested using data from Apensu, a structurally controlled gold deposit in Ghana. The required high-order spatial structures are obtained from a training image or analogue of the deposit. Using the available drillhole data and training image, HOSIM realizations are able to model well the grades and geometry of the large and well sampled mineralized structures. However, under-sampled small structures remain difficult to model. HOSIM offers a promising alternative for the spatial simulation of complex non-Gaussian orebody attributes of interest.

Jan 1, 2011

By L. Xia, B. Hart, J. Nigim, Z. Chen

"Grinding ore is an important step in the flotation process. Not only does grinding reduce particle size and liberate minerals, it also creates conditions for reactions to occur on particle surfaces that can aide or inhibit flotation. There have been numerous studies examining various grinding regiments and the effect on flotation pulp chemistry, including autogenous grinding and using media of variable composition. There have been however, few studies looking at the effect of variability in grinding media size on pulp chemistry and subsequent flotation. This study attempts to link changes in pulp chemistry in response to variations in grinding media size to flotation recovery. It uses probes mounted in the grinding chamber (pH, Eh, DO, and conductivity) to monitor pulp chemistry changes during grinding of a Cu-Zn ore. Surface chemistry analysis by ToF-SIMS was performed on sphalerite from the mill discharge. Activator and depressant species were monitored on the mineral surfaces and their presence was evaluated in the context of variability in pulp chemistry linked to differences in grinding media and its ball size.INTRODUCTIONIt has been widely recognised that not only does grinding reduce particle size and liberate minerals but the grinding environment has a large effect on the flotation of sulphide minerals. This effect is attributed to Eh change, iron hydroxide coating on surfaces, oxygen reduction, precipitation from solution and galvanic coupling (Grano, 2009). As early as 1960, it was reported that after grinding the ores in an iron mill the natural floatability of sphalerite was reduced significantly (Rey and Formanek, 1960). Kocabag and Smith (1985) studied on the industrial circuits showing that the depression of sulphides flotation in a steel mill is possibly due to the coating of iron oxidation products. Peng, Grano, Fornasiero, and Ralston (2003a, 2003b) found that iron contamination from grinding media plays a dominant role in depressing galena and chalcopyrite flotation. Huang, Grano, and Skinner (2006) reported the same observation in the flotation of arsenopyrite."

Jan 1, 2016

By Y. M. Shneerson, E. E. Zhmarin, E. M. Vigdorchik

One of the Gipronickel Institute activities is research and development of customized leaching technologies. The work is performed in several steps. Leaching kinetics are studied on a lab-scale according to a special procedure. Experimental data are processed using mathematical models of batch and continuous processes. Reliability of kinetic data and preliminary calculations is verified experimentally in laboratory reactors of various capacities. If necessary, certain parameters of the mathematical model are adjusted after pilot plant tests in continuous mode ( 4-reactor train, each with 25 L capacity). The specified kinetic characteristics along with the mathematical model are used for further development of industrial leaching technology.

Jan 1, 2005

By J. Shanks

In 1920 the writer presented some notes, embodying his experience with storage-battery locomotives as main under-ground haulage-motors at Brazeau collieries. (1) Since that date these motors have stood up well to the test of maximum output and heavy overloads, having accomplished all that was expected of them. The notes presented in 1920 gave a brief description of the conditions under which these motors were working at Brazeau collieries, also the cost, per ton mile, of operating them. The cost per ton mile has since then been appreciably reduced, by working the locomotives nearly to capacity and under more ideal haulage conditions, on both shifts. It is not the intention of the writer to repeat what was written in 1920, but rather to give members the benefit of his experience in operating different types or designs of locomotives; to draw their attention to the drawbacks of some designs, and to the improvements made in some of the more recent storage-battery locomotives put on the market, as regards efficiency, upkeep, and safety. Because of their flexibility storage-battery locomotives have advantages over any other type of haulage, where grades are suitable to their use. The number in use in the mines in the United States has increased enormously during the past few years, and this method of haulage is, at the present time, attracting the attention of British and Continental mining engineers.

Jan 1, 1924

The article presents an outline of methods and certain results of laboratory tests, underground tests and model tests, aimed at assessing performance of a powered shield support on the floor of low strength parameters. The tests were conducted within the framework of GEOSOFT project co financed by Research Fund for Coal and Steel (RFCR-CT-2010-00001). The described research works were conducted by Central Mining Institute (Glówny Instytut Górnictwa), Janina coal mine and Becker-Warkop

Aug 1, 2013

By Robert R. MacLachlan

New underground mining technology is evolving through the use of large-diameter bore holes containing individually restricted charge weights. This article presents summary observations on cube-root scaling trials using single and rows of charge blasting in sand and in frozen ground. These observations have some bearing on the evolving underground practice, especially where charges of appropriate geometry are used.

Jan 1, 1978

By D Martín, G. Díaz, F. Cubeddu, A. B. Mejias

The Modified ZINCEXTM Process (MZP), developed by Técnicas Reunidas, is an industrially proven flexible process. It can handle a wide range of primary and secondary raw materials, producing SHG zinc. The core of the Modified ZINCEXTM Process is the zinc solvent extraction unit. This unit is an effective barrier for any leachable impurities present in the raw material. As a result of this an ultra-pure zinc solution is always obtained. The high versatility of the process makes the application of the technology in different scenarios possible. MZP can be effectively applied when developing a whole new plant (Skorpion) or adapting its scheme to an existing refinery (Akita), in both cases giving the same results. Flexibility in terms of capacity of the plant is a great advantage of the MZP, there is the possibility to adapt the global process to a wide range of production capacities. Zinc production capacities of over 150 000 t/a may be achieved with a single solvent extraction plant train. The robustness of the Modified ZINCEXTM Process has been recently proven on two new plants currently in operation: Portovesme (Italy) and Horsehead (USA) after start up during 2013. The status of both plants is described in this paper.

Jan 1, 2014

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

By H. Perez, A. Lavoie, V. Prévost, P. Létourneau, P. Lind

The Home smelter is a custom copper smelter located in Rouyn-Noranda, Quebec. In 2005, the smelter produced 145,000 t of copper containing 807,000 oz of gold, 20,388,000 oz of silver in addition to 515,000 t of sulphuric acid. Recently, a flexible flow sheet has been developed incorporating the intermittent use of the Noranda Continuous Converter allowing for the increasing or decreasing of production based on market conditions, while attaining 90% or greater sulphur fixation regardless of operating mode. For 2006, the smelter is operating in full production mode and production is expected to be approximately 185,000 tm of copper. Mechanical modifications, process changes, metallurgical concepts, minor element treatments, and operational techniques that have allowed the smelter to develop this flexibility are presented. Current efforts to increase the productivity of the converter aisle and anode furnaces as well as improvements being made to address fugitive emissions are also discussed.

Jan 1, 2007

By Y. Chino

Cross-rolling, in which the roll axis is tilted by 7.5 degrees against the transverse direction, was carried out on a commercial magnesium alloy. The (0002) texture intensity of the cross-rolled specimen was lower than that of the unidirectionally rolled specimen. Also, the grain size of the cross-rolled specimen was smaller than that of the unidirectionally rolled specimen. As a result of the Erichsen tests at 433 ? 493 K, the press formability of the cross-rolled specimen was higher than that of the unidirectionally rolled specimen. The high formability of the cross-rolled specimen is attributed to both the reduction in (0002) texture intensity and the enhancement of grain refinement by the cross-rolling.

Jan 1, 2006

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 S. Spigarelli

The creep response of the AE44 magnesium alloy was studied by means of constant load creep tests carried out at 125 and 150°C, obtaining that at the latter temperature the minimum creep rate observed under an applied stress of 100 MPa was two orders of magnitude lower in the investigated alloy than in AM50. The minimum creep rate dependence on applied stress was described by a conventional power-law, e = Aon , where A was a temperature dependent parameter and n was the stress exponent, resulting in a n value close to 30, i.e. by far larger than those observed in commercial alloys with similar Al content. This large difference in creep response was attributed to the precipitation of rare earths (RE) intermetallic phases distributed in the grain boundary zone in form of an almost continuous network of dispersoids that were observed by means of scanning electron microscopy.

Jan 1, 2006