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By M. Cimenti

Fuel cells have tremendous potential as power sources but much fundamental research is still required. One key component of the research is the experimental set-up used. In particular, the placement of the reference electrode is extremely significant in measuring the half-cell overpotential of solid oxide fuel cells, since differences in area, misalignments, and also differences in the kinetics of the working and counter electrodes can cause both scaling errors and frequency distortions of the measured impedance. The impedance of thin solid electrolyte cells of different electrode geometries has been calculated using the finite element method and the results compared to experimental values obtained for the oxygen reduction reaction on platinum.

Jan 1, 2005

By Bryn Harris

Answer to the question is given as 42! Asked the wrong question So got the wrong answer How does this apply to the mining industry? And particularly to this session on Water? Water is just one aspect of mining/minerals/metals Should not be looked at in isolation Need to adopt a ?holistic? approach

May 1, 2013

By M. X. Yao, C. D. Opris, P. C. Patnaik, R. Liu, X. J. Wu

Two cobalt-based superalloys, Stellite 694 and Stellite 712, were functionally graded with reinforcement of titanium-carbide particle for high-temperature wear/corrosion applications. The designed composite specimens were fabricated using powder metallurgy (P/M) technique, combined with hot isostatic pressing (HIP). Calorimetric effects of the alloy powders were investigated using the differential scanning calorimetry (DSC) technique, which provided the basis of the sintering cycles designed. The phases present in the microstructures of the materials were analyzed using SEM and X-ray diffraction. The wear resistance of the materials was evaluated on a pin-on-disc tribometer. It was demonstrated that adding titanium-carbide particles to the alloys has increased significantly their wear resistance. It was also found that the HIP process had improved the density of the sintered specimens and thus enhanced their wear resistance.

Jan 1, 2004

By Fengxiang He, T. Meadowcroft, Yanjun Zhang

Slag from the zinc fuming furnaces contains about 3 percent zinc and 0.1 percent lead. The paper outlines several experimental techniques for recovering these components from liquid fumer slag. The simplest method, remelting followed by a hold period, indicated that a substantial fraction of the metal values was recoverable as a result of fuming into the gas phase, presumable by reduction of the metal ions by divalent iron ions. Following on from this, slag samples were equilibrated with copper, chosen because the activity coefficients of zinc and lead in copper are very low. This improved metal recovery, with substantial amounts of lead and zinc reporting to the liquid copper as well as to the fume. Application of an electrical emf across the slag-metal interface, using a graphite anode and a liquid copper cathode, resulted in further gains in metal recovery.

Jan 1, 2004

By Angela L. Paveley

Economic viability of base metal mining is complicated by a volatile market that can cause fluctuations in the growth and stability of the mining industry. Nickel is mined primarily for use in manufacturing industrial stainless steel and plating materials. It is essential that nickel production be sufficient to respond to current and future market demand. A Post-Pillar cut and fill mining complex is currently producing nickel sulfide in Northern Manitoba. From 2006 this area has shown a steady increase in the annual production, rising from 11 million pounds to 25 million pounds in 2010, and accounting for 33% of the total production for the Manitoba Operations. It is expected that fine-tuning the mining process can safely enhance ore recovery, improve production consistency, and increase economic viability of the deposit. The Post-Pillar Optimization study was initiated by the local technical and operational departments at the mine and analyzed from July 2010 to March 2011. The purpose of this study was to determine if portions of non-recoverable pillars can be slashed without jeopardizing pillar strength. This ideal case would optimize ore recovery and reduce variability in the ore mining rate. Numerical modeling and geo-mechanical material properties analyses, completed by the rock mechanics group, define the maximum drift width at 32 feet and the minimum pillar width at 18 feet. Thus, it was suggested that up to 3 feet could be slashed from two sides of the standard 24 foot pillars without damaging ground integrity. The field data collected indicates that additional ore could be recovered without compromising the safety of the workplace and the integrity of the complex. Consequently, technical and operational groups work jointly to achieve pillar optimization. Approximately 500,000 pounds of nickel was extracted from the complex via pillar optimization from July 2010 to March 2011. Economic analyses show the pillar optimization method developed for the mining complex is a proven, value-added opportunity. The mining complex remains a safe workplace and has retained ground integrity.

Nov 1, 2011

By J. W. Merks

"The accuracy of a measurement on minerals and ores can be assured by applying suitable and unbiased procedures but its precision is a function of the number of primary increments and their mass, the number of lots per consignment or samples per shift, and the number of measurements on analysis fine samples.Experimental data will be used to show how the variance components for sampling, sample preparation and analysis contribute to the total variance on which precision statements for the final measurement are based. This type of experiment should not only form part of quality control programs at mines and smelters, but also underly the criteria on which the design of manual sampling regimes and mechanical sampling systems for bulk solids and slurries should be based.Sampling systems and regimes can only be adjusted and optimized if the variance component for each step in a quality evaluation process is measured. Knowledge of precision characteristics lies at the core of effective loss prevention and control programs."

Jan 1, 1985

By Zhanyou Huang

The logic and capabilities of a short-term planning tool are presented. It was developed using mixed integer linear programming (MILP) techniques to solve the open-pit and underground mine planning problems that include multiple mining areas, multiple processes, multiple destinations and blending requirements. It finds the optimum schedule that achieves the objective while satisfying comprehensive product quality and quantity requirements, equipment utilizations, as well as physical and technical constraints. A case study is given to demonstrate its applications.

Oct 1, 2009

By Zhanyou Huang

The logic and capabilities of a short-term planning tool are presented. It was developed using mixed integer linear programming (MILP) techniques to solve the open-pit and underground mine planning problems that include multiple mining areas, multiple processes, multiple destinations and blending requirements. It finds the optimum schedule that achieves the objective while satisfying comprehensive product quality and quantity requirements, equipment utilizations, as well as physical and technical constraints. A case study is given to demonstrate its applications.

Oct 1, 2009

By Noko S. Phala

The energetics of CO and CO2 hydrogenation to methanol were studied on a gold surface via periodic and cluster DFT calculations. CO hydrogenation appears to be much easier than CO2 hydrogenation on an Au(111) surface. The use of a cluster model does not seem to improve the energetics of CO2 hydrogenation. It is concluded that an active support (e.g. ZnO) will be required to increase the productivity of a gold surface towards synthesis gas conversion. The energetics of CO and H2 adsorption are improved on the cluster model compared to a slab model of an Au(111) surface, suggesting that nanosized gold particles may be beneficial in CO hydrogenation.

Oct 1, 2003

By Lee W. T. Weitzel

This paper reviews the Falconbridge- SMRQ?s Raglan project in northern Quebec and the process that was used in developing its current long-term mine plan. Challenges were many and not only limited to the longevity of the project, numerous ore deposits (both underground and open pit), and a 40km property strike length. As a result of its remote northern location other factors such as progressive reclamation, leachable mine waste, water treatment, and waste management were also part of the plan. A combination of modern planning tools were used to formulate the plan including DataMine, Mine 2-4D, AutoMod Simulation, and an Excel based financial spreadsheet to bring the total plan together. The focus of this paper is to show the complexity of modern mine planning and associated economic modeling of mine processes.

May 1, 2002

By M. Doucet

The introduction of high-nickel anodes to CCR in 2006 resulted in an increase of nickel in anodic slimes. Removal of the nickel in these slimes to below 3.0% is necessary in order to prevent slag viscosity problems in the subsequent pyrometallurgical step. A lower specification of 0.5% was chosen in order to minimize Ni losses to the slag and to recover this nickel as NiSO4. A 2-stage autoclave process, which was patented by CCR in 1992, was chosen to treat the high nickel slimes. Laboratory and plant?scale tests were performed in 2004 in order to validate the results of this process with the present slimes. These results along with corrosion tests were used to design two brick-lined autoclaves. These autoclaves were installed in October 2006 and successfully commissioned within 8 weeks. A "Design of Experiment" test program was performed in 2006 on an alternative autoclave process that reversed the cycles in the patented process. The effects of temperature and acid content were modeled using the results. The alternative process will be validated with the new autoclaves.

Jan 1, 2007

By Mario A. Morin

The last few years have seen considerable consolidation of the mining software industry and a trend towards greater planning and production control system integration, particularly for surface mines. The mining industry is starting to realize the benefits of system integration and will continue to drive the evolutions of these systems. Several trends can now be observed. The trends include application and system integration, data portability, ?intelligent? systems for support of decision-making activities, mine process-control and automation. While many planning systems are moving in this direction, there is room for considerable improvements. This paper will discuss these trends, examine the current state-of-the-art in mine design software, and identify areas where improvements should be made and why.

May 1, 2004

By H. Dundar

The first application of High Pressure Grinding Rolls was in 1985 at a cement plant, for the purpose of capacity improvement. Then various circuit configurations were derived to achieve a reduction in overall specific energy consumption, by transferring more of the grinding required to the HPGR. In most circuit configurations, the recycle of fines is required for effective breakage between the rollers. By increasing the fines amount in the feed material to a specific level within the recycling load, a uniform material bed is created and a higher pressure gradient along the roller width is obtained, resulting in compact flakes, including more fines. The fines recycle results in enhancement of the interparticle breakage. This paper will discuss the effect of the feed size distribution on HPGR performance.

Jan 1, 2012

By Yongqiang Liu

Background For refractory gold ores with high carbonate contents ! Acid pressure oxidation ! High acid consumption (if low sulfur content) ! Low oxidation efficiency due to CO2 in autoclave ! Problems with slimy precipitates (gypsum, etc.) ! Alkaline pressure oxidation ! Difficulty in fixing arsenic ! Low gold dissolution due to iron hydroxides/oxides coating ! High reagent costs Summary ! Carbonate and sulfide minerals had similar floatability across the pH range tested (5 - 12) using sodium oleate as a collector; ! Thioglycollic acid or citric acid depressed the flotation of pyrite but could not depress chalcopyrite when used alone; ! Combination of thioglycollic acid and citric acid had a much stronger depressive effect, and the mixture depressed chalcopyrite as well as pyrite between pH 8 and 11 without affecting the flotation of calcite and dolomite; ! Calcite could be separated from chalcopyrite and pyrite; dolomite could be separated from pyrite but not from chalcopyrite under the tested conditions.

Apr 1, 2005

By Geoff Goodyear

UHNL Corporate Profile ? Providing Helicopter Services since 1963 ? A Newfoundland Company head-quartered in Goose Bay, Labrador ? Operations, while primarily Atlantic Canadian, extend across Canada, the Arctic, Greenland ? 16 aircraft, all single engine / VFR Typical Industry Mission Profiles & Work Environments ? Types of missions include: ? Air Taxi & Executive Transport ? Mineral Exploration ? Forest Fire Suppression ? Medivac ? Wildlife Management & Research ? High Angle Rescue and Ice Blasting ? External Load & Long Line ? Mountainous Terrain Operations ? Aerial Application ? Power line Patrols & Construction The Helicopter ? Essentially the same aerodynamic principals as fixed wing but with some mechanical variations on the theme

May 1, 2001

By G. A. Campbell

This paper looks at how changes in the economies and demographics of the eight largest copper-consuming countries have been affecting their consumption of copper. The period of 1976 to 2005 is considered. Annual changes in measures like intensity of use of copper, per capita consumption of copper, copper consumption based on per capita income, and copper consumption from industrial production for each country and in aggregate are calculated. Other factors like the change of industrial production relative to total GDP and population/age trends are also considered for the individual countries. Non-parametric and parametric statistical tests are used to determine the significance of observed trends and relationships for individual countries and in aggregate. The results give insights into how copper consumption is changing for the countries and what economic/demographic factors are driving these changes. These insights provide some guidance about where copper consumption trends are headed in the future.

Jan 1, 2007

By Wencheng Gao

An attractive way to beneficiate magnesium chloride and aluminum chloride is to prepare Mg-Al spinel, an excellent refractory material. Mg4Al2(OH)14?3H2O, the precursor of spinel, can be prepared using a co-precipitate method from aqueous MgCl2-AlCl3 solutions. The co-precipitation process of magnesium-aluminum from acidified chloride solutions by using NaOH or NH4OH as base neutralization agent was studied. Co-precipitation was conducted from different mixed solutions ? at initial CAl=0.0625M and Mg/Al molar ratio from 0.5 to 10, the temperature range from 30 to 90 °C. The effect of other parameters, including base type, method of base addition, base addition rate, aging time, background electrolyte and concentration were also investigated. The co-precipitation process was monitored by potentionmetric(pH) measurements. The experimental pH curves were characterized by two platforms separated by a steep jump in pH at Mg/Al molar ratio 0.5~6. The first platform was centered at about a pH of 3.8 and the pH of second platform was varied with different conditions. When the Mg/Al molar ratio was up to 6~10, the first platform in pH was almost disappeared. Furthermore, the shapes of pH curves were also affected by base type, base addition rate and method of base addition. Experimental results showed that the first platform in pH was connected with Al precipitation, and the second platform was involved with Mg. The final co-precipitates were characterized by XRD, TGA-DTA, particle size analysis, SEM and TEM. We found both Mg/Al molar ratio and temperature proved to be the key parameters controlling the formation of Mg4Al2(OH)14?3H2O phase. At solution Mg/Al ratio=0.5~4, the main precipitate phase was Bayerite (Al(OH)3) admixed with Mg4Al2(OH)14?3H2O; at Mg/Al ratio=4~6, the main phase was Mg4Al2(OH)14?3H2O admixed with some Mg(OH)2; while from Mg/Al ratio=6~10, the systems were mixtures of Mg(OH)2 and Mg4Al2(OH)14?3H2O.

Oct 1, 2011

By N. Maleki

In recent years, research and development of magnesium alloys have been greatly promoted by the lightweight requirements in critical industries. The use of these alloys, however, has been restricted by their limited mechanical properties especially at high temperatures. The disadvantages can be overcome by producing Mg matrix composites. The Mg?Si alloys containing in situ Mg2Si particles have found a great potential as structural materials. Unfortunately, Mg2Si compounds are prone to form undesirable coarse Chinese script morphologies, which would deteriorate the properties of the materials. Refinement of microstructure is performed for improvement of wear and corrosion resistance. This paper investigates the microstructure and corrosion behavior of pure magnesium, unmodified and modified magnesium matrix composites reinforced with Mg2Si particles. The Mg2Si/Mg composite was prepared via a normal cast route, and then various amount of zinc was added to melt in order to modify the Mg2Si reinforcement particle morphologies. The microstrucrures were characterized by optical and scanning electron microscopy followed by EDX analysis. The corrosion behavior of Mg/Mg2Si composite was investigated by using potentiodynamic polarization measurements. The results showed that by addition of zinc, the average size of the primary Mg2Si became significantly decreased from about 100µm to about 20µm, as well as its morphology changed from dendritic to a polyhedral shape. However, by adding extra amount of zinc many primary Mg2Si particles become coarse again. It was also found proper amount Zn addition increased the corrosion resistance of Mg/Mg2Si composite.

Oct 1, 2011

By R. Harris

The vacuum thermal route for magnesium production today accounts for roughly 80% of the global production of magnesium despite significant investment in the competing electrolytic technologies, This is up from 30% of the global production 10 years ago and is all the more significant because global magnesium production has more than doubled in the same time, A review of the sophisticated anhydrous magnesium chloride production technologies provides some explanation for this sea change in technology usage, However, an examination of the economic factors provides compelling reasons, The present review outlines some of the salient strengths and weaknesses of the competing technologies, It also offers suggestion as to where future R and D and economic effort needs to be vested to improve the sustainability of the world magnesium market in terms of its value and impact.

Jan 1, 2006

By A. Chaisantikulwat

Most solid-oxide fuel cell (SOFC) modeling emphasizes steady state cell operation. However, understanding the dynamic behavior is essential to predict the performance and limitations of SOFC power systems. In this work, we demonstrate a dynamic model of a SOFC, and we simulate a feedback control scheme that can maintain output voltage despite load changes. Dynamic response is determined as the solution of coupled partial differential equations derived from conservation laws for energy, mass and electric charge. From such a model, the step responses to system input variables can be determined. Low order dynamic models that are sufficient for feedback control design can be derived from the step responses. The development of the partial differential equation model is outlined, and the limitations of the control system are discussed.

Jan 1, 2005