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By Pritii Tam Wai Yin, Tony Leong, Neetu Bansal, James Vaughan, Amiel Boullemant

Mercury is a toxic element that is associated with many industrial activities including the Bayer process. Mercury is known to enter the Bayer process with the bauxite feed material and has the potential to accumulate as the process solution is recycled. This paper explores the speciation of mercury in Bayer process streams. The process parameters considered are the oxidising-reducing potential, basicity and temperature. The results of a refinery circuit survey are presented and compared with the thermodynamic predictions. Electrochemical measurements on relevant synthetic systems are also included.

Jan 1, 2014

By F. Crundwell, N. Steenekamp

"The leaching of sulphide minerals generates a significant amount of energy. There are three systems that might be used to remove this energy. These are: cooling coils, quench water, and flash recycle. Flash recycle is the recycling of slurry from the autoclave to the feed tank. Heat is removed in this arrangement when the slurry at elevated temperature and pressure is flashed to atmosphere, releasing steam. The slurry is returned to the autoclave at lower temperature, resulting in cooling. The cooling is directly proportional to the steam released from the recycled slurry. Design equations and results for the flash recycle system are presented. A fourth proposal for removing heat is to recycle slurry from the back of the autoclave. These four alternatives not only remove the heat, but also have an effect on the leaching efficiency. Amongst the four alternatives, design calculations indicate that the flash recycle option is the optimal solution in terms of leaching efficiency and heat removal, and recycling product from the back of the autoclave is the worst. In spite of its efficiency in terms of heat removal and leaching, the implementation of the flash recycle system is limited to a few operations in the platinum industry.INTRODUCTIONIn considering ways to improve leaching operations, focus is placed on the chemistry, on the kinetics, the agitation and perhaps even on the gas mass transfer conditions. Attention is less frequently placed on the removal of energy from these reactors and how this might limit performance.The pressure leaching of sulphides releases a significant amount of heat. For example, the reaction for the leaching of chalcocite, Cu2S, given by"

Jan 1, 2012

By R. S. Douglas

Introduction During the past few years, a number of changes in the mine operations at Copper Mountain have taken place. The modernization and mechanization were necessitated and given impetus by wartime and other conditions, which were: (1) The urgent need for copper for wartime purposes. (2) The scarcity of skilled labour for underground work. (3) The increase in labour and supplies cost. (4) The necessity of finding ways and means of increasing the output per man-shift, because of the scarcity of skilled labour and the rising cost of labour. (5) The desire to increase safety measures, reduce the silicosis hazard, and aid mine ventilation. (6) The desire to improve the general working conditions in the mine for all workmen. (7) The desire to reduce the amount of dilution in the ore stream by a more selective yet highly productive method of mining. To this end, mining with diamond drills, and transferring broken ore with slusher hoists, appeared to be the answer to the problem. After considerable discussion and estimation of costs for comparison with those of the operation as carried on at that time, the proposed methods were tried out and, in practice, gave very gratifying results. Reference at this point is made to the paper written by C. H. Brehaut, W. N. Taylor, H. A. Shannon, and R. S. Douglas, which was published in the September, 1945, issue of Mining Technology, by the American Institute of Mining and Metallurgical Engineers, Inc., and subsequently in commercial mining journals. Since that time some improvements have been made in undercutting an orebody - the first through experiment and practice, the second through making use of the earth's barodynamic or gravitational forces. It is the purpose of this paper to describe and discuss these later developments.

Jan 1, 1947

By A. E. M. Warner, A. Vahed, P. J. Mackey

"Since early 2015, the price of nickel has dropped from the region of US$6/pound to current levels of around US$4.60/pound (March 2017), reflecting several market factors, but principally due to lower demand from China. Under such conditions, nickel companies have been under pressure to contain operating costs. In addition, labor and energy costs will continue to rise, while nickel ore grades will likely continue to drop. All major companies now accept the need for climate change action and consequently efforts are being made towards lowering carbon-based emissions. Nevertheless, meeting these challenges can also contribute to higher operating costs without parallel innovative developments - which at the same time, under current conditions, major companies are tending to curtail. In this paper, several productivity improvement opportunities to reduce unit operating costs at nickel sulphide and nickel laterite plants are reviewed. Opportunities include: (a) process technology and energy-type selection, production capability, optimization of process intensity and implementation of newer technologies; (b) improved productivity, equipment availability including maintenance best practice; (c) energy savings and recovery opportunities and use of energy surveys and, (d) process modeling and improved scheduling. Such improvements along with an uptick seen in nickel demand going forward should better position the world nickel industry.INTRODUCTION Nickel is an essential metal to modern society, primarily through its use as an important ingredient in stainless steel. Thus, stainless steel finds vital applications in food preparation facilities, as well as important uses in transportation and industrial applications. Canada has always played an important role in nickel production and nickel metallurgy. In the 1940s and 1950s, Canada supplied over 90% of the world’s nickel. However, this proportion has declined considerably to around 10% of the world nickel supply today. Still, Canada remains an important nickel supplier and contributor to nickel extractive technology. Due to the importance of nickel to society, nickel demand is expected to continually rise. On the other hand, nickel companies have been under pressure to contain production costs amid languishing nickel prices. While demand projections show nickel growth, there are uncertainties in actual levels of future market growth. Ore grades are dropping, while labour and energy costs, which are key cost contributors are rising, hence efforts to lower production costs will generally require innovative approaches."

Jan 1, 2017

By A. Alwasel

Musculoskeletal disorders (MSDs) threaten the wellbeing and livelihood of a large number of construction workers incurring a significant cost to society. We present a new method to monitor and diagnose MSD risks in the workplace. The sensing unit of the system is an optical encoder encompassed within a non-intrusive exoskeleton to measure the joint angle of interest. This sensor can be applied to ball-and-socket and hinge-type joints of the human body, such as the shoulder, elbow, and knee joints. The system is contactless and does not require markers or cameras. Angle measurements are acquired directly without mathematical post-processing, thereby avoiding numerical noise and drift challenges. The system is a simple, robust, and deployable, but it currently lacks resolution of parallel degrees of freedom.

Aug 1, 2013

By D. D. Bell

This paper presents the history of uranium procurement and demand, and takes a look at future requirements. The three basic conclusions drawn are: (1) the productive capacity of former and existing producers whose operations may be profitably reactivated is insufficient to meet demand projected beyond 1975; (2) reserves in the $5 -$10 price range do not provide the flexibility to sustain production at the high rates required in the late 1970's; and (3) only higher prices can overcome these deficiencies, as this would provide sufficient inducement for the industry to explore for and develop new reserves and productive capacity.

Jan 1, 1967

By H. J. McQueen

Mineral and energy resource consumption were continuously reduced by process improvements as chemical understanding was developed and applied. During the past two centuries, technological improvements increased human productivity that was accompanied by social advances and labour saving products; however, these sometimes proliferated to endanger sustainability, e.g., automobiles. In the steel industry, precisely controlled rolling of HSLA steels required little extra mineral consumption but reduced weight and heat-treating energy. Continuous casting of slabs reduced scrap compared to ingots and energy for the homogenizing soaking pit. Al alloy extrusions were improved by retaining the strengthening in the near-surface substructure, of high strength textures and of press quenching that is suitable for direct age hardening. Continuous bar casting of Al-0.65Fe, coupled with rod rolling and followed by wire drawing with only a final recovery anneal, yielded electrical wiring for households to replace less plentiful Cu and later for light-weighting use in autos and aircraft Looking backwards, the 1970 decade saw the first oil crisis and inspired Ottawa to undertake a campaign to develop an energy strategy that would decrease dependence on imported fuels. One significant undertaking under Energy Mines and Resources was the organization of industrial energy conservation, managed by each industry association,that collected detailed current statistics and set the goals for a 2-year campaign. The metal producing industries, as compared by E.C.N. Perryman to about 7.2 exajoules (EJ) for the nation, consumed about 0.8 EJ, being about one third of all heavy industries. While manufacturing consumed 30.2% of total energy, it created 87.3% of total national dollar value. Within the industrial envelope, smelting and refining utilized 28% (0.67 EJ, mining beneficiation 6.7%, 0.16 EJ); there was a significant contribution to exports: 80% of iron ore and 70% of aluminium in 1973. A general concern was that decreases in ore grade would lead to a rise in energy expenditures countering benefits from processing efficiency.

Jan 1, 2012

By Robert B. Parsons

"The tax reform process marches on. The December 16, 1987 measures tabled by Finance Minister Michael Wilson represent one more step toward the objective of total reform of Canada's income and sales taxes. While the income tax changes are taking shape, much work still needs to be done on the sales tax side of the coin.IntroductionOn December 16, 1987 Finance Minister Michael Wilson tabled measures to implement the changes to Canada's income tax system that were proposed in the June 18, 1987 White Paper on Tax Reform. The measures were set out in a Notice of Ways and Means Motion; draft legislation relating to preferred shares, research and development expenditures; and draft regulations regarding capital cost allowance, certified films, flow-through shares, and the resource sector. The reaction of the government to the recommendations made by the Finance and Economic Affairs Committee Report on Tax Reform (the Blenkarn Committee), the Report of the Standing Senate Committee on Banking, Trade and Commerce and through consultations with interested groups and organizations, business, labour and individual Canadians is set out in a booklet of supplementary information.The basic features of the reformed income tax system set out in the White Paper remain. However, a number of significant changes have been incorporated in the Notice of Ways and Means Motion and other material. The following comments address those area s where changes have been made to the original White Paper proposals."

Jan 1, 1988

By A. L. Mular

This paper provides a worthwhile contribution to the knowledge needed for calculating and using mathematical models of grinding circuits. The computer search algorithm proposed should remove much of the guesswork as well as reduce computer processing costs and improve the accuracy of estimated parameter values for grinding mill models.

Jan 1, 1970

By H. Qi, J. L. Feng, D. J. Li

"In the present paper, the characteristics of the granite burst under loading/unloading conditions was studied by means of both laboratory experiment and finite-discrete element method (FDEM). After gaining the mechanical properties of the granite samples under uniaxial compression conditions, the parameters taken as input arguments in the FDEM modelling were then carefully calibrated so as to provide some basic data including Young’s modulus, Poisson’s ratio, uniaxial strength, Lame constants, cohesive strength, and frictional angle for further being used in simulating granite bursts. All the simulating results by the FDEM were basically in agreement with that obtained from the uniaxial compression test and triaxial granite bursts in laboratory, respectively. This study shows that that such computational mechanics of discontinua can be employed to gain powerful insight into the failure mechanism of granite burst, which could also be a useful tool to clarify the collapse mechanism of rock structures in rock engineering design and rock test scheme optimisation. INTRODUCTIONBased on discontinuum state a priori, discontinuous modeling techniques that are commonly referred to as discrete element methods (DEM) treat the material directly as an assembly of separate blocks or particles, which was originally proposed by Cundall (1971) and Cundall and Strack (1979) from the viewpoint of analogous molecular dynamics simulation to better account for and understand the interaction between the blocks. The distinct feature of these formulations is that a constantly changing problem of geometry and contact conditions can be addressed by solving the equations of motion using an explicit time marching scheme (most often in a ‘leap-frog’ format), while updating contact force histories as a consequence of contacts between different discrete elements and/or resulting from contacts with model boundaries (Bicanic 1998). The most notable implementations of DEMs are arguably represented by the universal distinct element code (UDEC) (Itasca Consulting Group Inc., 2013) and the particle flow code (PFC) (Itasca Consulting Group Inc., 2012). Another formulation is the discrete crack framework that is based upon some criteria for an advancement of crack front, which is coupled with extensive local and global re-meshing while simulating by numerical methods such as finite element technique, commonly using fracture theories. Certainly, it is relatively easy to trace the propagation of single crack front governed by some principles of energy release rates (Ingraffea 1997) but tracing of multiple cracks leads to topological and algorithmic complexities. Otherwise, there is no consideration of interacting cracks in these formulations of finite element or enhanced finite element techniques (e.g., in XFEM and ABAQUS)."

Jan 1, 2015

By L. Rodd, C. Walker, T. Koehler

"The energy content of slag represents approximately 80% of the total energy inputs to a laterite nickel electric smelting furnace. Conventional slag handling methods produce only low grade heat and the entire thermal content of the slag is wasted. A heat recovery system proven on BOF slag in the mid 1980's can be adapted to a laterite nickel rotary kiln electric furnace (RKEF) plant. Slag is granulated using a high velocity air jet inside a waste heat boiler to produce slag granules. Granules are cooled during flight via radiation to water-cooled boiler walls and by convection to the granulation air. This system has the potential to recover 80% of the total slag energy in the form of hot air and steam.Integration of the recovered slag energy into the RKEF smelter can be achieved by a number of methods, including the use of preheated air at the ore dryers, kiln or existing power plant. Energy from the slag boiler may be used to reheat boiler feed water from the power plant or to produce superheated steam and generate electricity. The heat recovery system can provide up to 25 - 30% of the total electrical requirement of each RKEF line and a reduction in CO2 emissions of 234,000 tonnes per year.The total cost of slag heat recovery, including CAPEX and OPEX, is $2.5/GJ, which is competitive with using coal when CO2 credits are $18 per tonne. With Clean Development Mechanism (CDM) carbon credits currently selling at €13 ($20 USD) per tonne CO2, there is considerable opportunity for slag producers in regions including South America, Korea, Indonesia and Africa. Increasing fuel costs and more wide-spread legislation for GHG emissions will likely create conditions in which slag heat recovery could generate a favourable return on investment."

Jan 1, 2010

By D. K. Fountain

"High metal prices and advanced technology in open-pit mining methods have resulted in considerable interest in the development of large, low-grade mineral deposits. Brenda Mines Limited is presently testing such a deposit of copper-molybdenum mineralization near Penticton, British Columbia.The mineralization of economic interest at Brenda has a total metallic sulphide content of between 1 and 1.5 per cent. This sulphide content approaches the limits of detectability of standard geophysical methods. How-ever, due to a favourable geological environment, it has been possible to utilize the Induced Polarization Method to outline the mineralization at the Brenda property."

Jan 1, 1968

By R. Wirth, B. Orberger, C. Wagner, A. Tudryn, B. Baptiste, S. Miska, Université Paris-Sud

Banded iron formations (BIFs) comprise complex textures and mineralogy, which result from fluid-rock interactions related to high and low temperature alteration. The initial iron oxy hydroxide mineralogy and associated phases such as carbonates, quartz, apatite and phyllosilicates were transformed leading to an upgrading of these BIFs into the world’s largest source of iron ore. In low-grade BIFs, a large part of the iron is related to micro- and nano- metric iron-bearing inclusions within micrometric quartz and/or carbonates (mainly dolomite). We studied laminated jaspilitic BIF samples from a drill core containing 26.71 wt.% total iron, 0.2 wt.% SiO2, 0.32 wt.% MnO, 15.46 wt.% MgO, 22.32 wt.% CaO, 0.09 wt.% P2O5, < 0.05 wt.% Al2O3, 0.15 wt.% H2O and 34.08 wt.% CO2 (Aguas Claras Mine, Quadrilatero Ferrifero, Brazil). Bright rose coloured dolomite and quartz bands alternate with massive specular hematite bands. Raman spectroscopy, X-ray diffraction and FIB-TEM analyses reveal that the micro- and nanometric inclusions in dolomite are mainly hematite and minor goethite, partly occurring as clusters in voids. Curie Balance analyses were carried out at different heating steps and temperatures on whole rock samples and a synthetic mix of decarbonated sample and pure dolomite. X-ray diffraction on the products of the heating experiments shows that that hematite is stable and new phases: magnesioferrite (MgFe2O4), lime (CaO), periclase (MgO), portlandite (Ca(OH)2) and srebrodoskite (Ca2Fe2O5) were formed between 680°C and 920°C. These finding gives hints to optimizing the beneficiation process, as the presence of hydroxyl ions bearing goethite micro- and nanoinclusions lowers the sintering temperature. Prior separation of coarse hematite and barren dolomite and quartz, followed by lower temperature sintering of the inclusionbearing dolomite/quartz leads to transformations into phases with higher magnetic susceptibilities (such as hematite and magnesioferrite). The entire Fe and Fe/Mg oxide feed (the priorly separated fraction added to the sintered fraction) can then pass through wet-high intensity magnetic separation after crushing.

Jan 1, 2016

By S. Shairp

"After cooling and thickening, slurry from the second stage of the Hudbay zinc pressure leach circuit is filtered and washed on a belt filter prior to disposal. At times, the belt filter can be a bottleneck to the process. Preliminary studies show that filterability of the second-stage (HAL) autoclave leach residue can be indicated by particle size distribution of the filter feed and filtered residue cake. In particular, the Volume Weighted Mean Diameter, D[4,3], generated by a laser diffraction particle size analyzer from samples of HAL Filter feed, shows residues that filter more poorly have a lower Volume Weighted Mean Diameter than those that filter better. INTRODUCTIONHudbay produces cast zinc metal from blends of zinc concentrates at its metallurgical complex in Flin Flon, Manitoba, Canada, using Sherritt’s two-stage pressure leach process (Collins et al., 1994; Collins et al., 1995; Barth et al., 1998; Shairp et al., 2006). Pressure leaching replaced the original roastleach- electrowinning process in 1993.Filtration for the second-stage (HAL) leach residue originally consisted of two stages of vacuum drum filtration with intermediate cake repulping stirred tanks. As part of Hudbay’s 777 Project, with a designed increase in cast zinc production, a pre-feasibility study by SNC-Lavalin Inc. showed that losses of soluble zinc in the zinc pressure leach residue could be reduced by installing more efficient filtering and washing equipment. Based on laboratory performance, capital cost, installation ability, and potential operating cost savings, a 70 m2 Filtres Phillipe belt filter was chosen for the HAL residue, and commissioned in 2000/2001.When the HAL belt filter is performing well, there is no pooling of water on the surface, moisture content is relatively low, and subsequent analysis shows that water soluble zinc content is relatively low. There have been occasions where the filter has performed poorly with respect to the aforementioned parameters. Aside from the filter experiencing mechanical difficulties, there are several variables affecting leach residue filtration:"

Jan 1, 2012

By D. Tetsuka, H. Okamoto

The amount of impurities to be processed in a copper smelting process has increased for recent years because of an increase in the electronic scrap amount. It has been found that Sb and Ni effect on the operation of our copper electrorefining process. It is found that the current efficiency of the copper electrorefining tended to be decreased as the Ni concentration in the electrolyte increased. The passivation of the process seemed to be more related to SO4 concentration in the electrolyte rather than the Ni concentration in it. The current efficiency decreased when the Sb content in the anode was high. A high Sb content in the anode caused easy passivation by forming a gel-like film in the slime layer. We have developed a method to for see the anode passivation in a short time while generating a slime layer. We confirmed the tendency of passivation through the experiment of changing Pb content in anode. Passivation was easily occur with an increase in Pb content in the anode. The amount of slime increased as the Pb content in the anode increased. This suggests that passivation was facilitated because liquid diffusion near the anode was inhibited. INTRODUCTION The amount of impurities to be processed in copper smelting has been growing in recent years because the amount of electronic scrap has increased. Figure 1 shows that the contents of Sb and Ni in copper anodes have increased since 2007.High Sb and Ni contents in the copper anode decreased the current efficiency of the process and made the quality of copper cathode poor because of the anode passivation and the formation of floating slime in the electrolyte during electrorefining. If these influences of impurities are suppressed, it would be possible to make copper electro-refining current density higher and to process much amount of electronic scrap. We examined the components of our copper electro-refining process like anode composition, slime properties and electrolyte composition, and investigated the mechanism by which Sb and Ni affect passivation and current efficiency. When examining the influence of Ni, we noticed that the SO4 important. The effect of SO42 – was also discussed

Jan 1, 2019

By D. Pacey

"This paper reviews the installation, start-up, and operation of a comprehensive monitoring and targeting management technique in which all plant utilities (i.e., electricity, natural gas, compressed air, and water) are managed as controllable resources in the same way that raw materials, mined ore, personnel and capital are managed.The essential elements of monitoring and targeting (M&T) include:•gathering in a systematic, disciplined way the utility information by energy account centres;•closely monitoring the utilities used in each centre and comparing them with production on a common time base (e.g., kWh/ton per day);•bench marking and target setting to pro-vide attainable energy reduction goals which can be further refined as they are achieved; and•establishing an implementation plant that may provide efficiency enhancing benefits to various operating areas within the plant.The M&T system will reduce utility consumption per unit of production on a continuing basis.This would translate into sustained operating cost and waste. M&T will also provide better information for assessing the plant operation and progressively implementing further enhancements."

Jan 1, 1997

By M. Cossette, P. C. A?tcin

At present there is considerable confusion in the asbestos industry with regard to density and porosity measurements of asbestos. In order to clarify the situation, various notions of porosity and density are defined by means of simple schemes and clear symbols are proposed to denote them. An experimental procedure is then preposed and outlined, which is based upon Archimedes' principle. Experimental conditions at each stage of the method are explained clearly in order to minimize the opportunity for errors. Finally, the results of a study on the porosity and density of asbestos minerals having various characteristics are presented.

Jan 1, 1972

By D. Fodor

In Romania, there are significant lignite and brown coal reserves hosted by different regions of the country. The most important lignite bearing zone of the country situated in the North ? West part of Oltenia region and which covers a surface area of 2,500 km2 and host a total reserve of 3.0 billion tons of lignite, of which more than 95% can be exploited by open cast method. The paper deals with the existing geological and mining conditions of the zone , the distribution by mining basins and exploitation perimeters, the open cast working technologies and the economic outcomes obtained throughout the time. Years ago, for the improvement of the economic situation as a whole and in each unit, a large production reorganization, technology update and modernization process was started up. There are described the rehabilitation measures of the technological lines and modernization of the equipments of the production flow-sheet, measures developed at present, too and which will still continue in future. There are mentioned the equipments considered, the components under modernization and the economic outcomes obtained so far. At the end of the paper there are presented the future actions for the equipment modernization and perspectives of the lignite deposit exploitation to meet the national economy requirements of solid fuels.

Aug 1, 2013

By Joseph Hirschi, Behrooz Abbasi, Harrold Gurley, Yoginder P. Chugh

"The research goal was to assess if analytical tool/s can be developed to quantify displacements around a geological fault as longwall face moves toward it and past it. A company was faced with crossing a 2-3 m (6-10 ft.) normal up-thrown fault in the development entries and the face while mining a 375 m (1,200 ft.) wide longwall face. A field monitoring and numerical modeling study was performed to develop data. Field measurements consisted of roof-to-floor convergence and rectangular rosettes in the immediate roof. Numerical modeling consisted of constructing a 3-D structural model using the FLAC3D software with the fault plane incorporated as ubiquitous joint. Based on analyses and field observations data, the coal company was informed of impending movements along the fault plane and likely impacts on the development entries. Additional stiff supports were installed in head gate entries around the stage loader and equipment about 60 m (200 ft.) outby of the longwall face (solid). As the longwall face approached the fault, predicted displacements were documented and manifested by severe loading on the installed supports.BACKGROUND AND STUDY OVERVIEWThis paper summarizes results of a cooperative study aimed at improving longwall mining operations in Illinois. More specifically, the study focused on: 1) In-mine measurements in development entries while mining ahead of and behind a faulted zone, 2) Making observations on stability of pillars and entries while mining through the fault, and 3) Developing simplified analytical structural models using FLAC3D to assess if predictive techniques can be developed to plan mining operations through fault zone. Available data on geometry of the fault with estimates of the cohesion and frictional parameters were used for modeling."

Jan 1, 2015

By R. M. S. Häggblad

The article deals with stabilisation and regeneration of Ce02 and Ce02/Zr02 based Pt water gas shift catalysts, subject to high initial deactivation. The reaction gas species effect on the catalyst deactivation was investigated by H2-TPR. Activity measurements enabled the effect of different promoters, some added to the Ce02 based catalysts and some to the Ce02/Zr02 based Pt catalysts, to be investigated. The catalysts were also characterised by BET and CO-TPR. Deactivated catalysts activity was restored by using various regeneration methods. Of the two selected carriers the Ce02/Zr02 based Pt catalyst showed the highest resilience to deactivation. For the two different carriers, Ce02 and Ce02/Zr02, Wand Re were the best promoters when the catalyst was subject to deactivation. Experiments with Hr TPR indicate a fast initial change in the platinum oxides concentration and composition. The CO-TPR was used to make conclusions about the various regeneration effects of water and oxygen on the catalyst. Finally it is suggested that not one deactivation mechanism is possible and which mechanism that dominates is dependant on the catalyst and the reaction gas composition.

Jan 1, 2005