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By Ian Hattie, Mark R. Wilson, T. Kurtis Kyser, Brian W. Janser

Petrographic, chemical and isotopic compo itions of auriferous and non-auriferous quartz vei ns from the Sta r Lake and Flin Flin-Amisk Lake areas of northern Saskatchewan indicate diver e origins fo r the fluids associated with gold mineralization. In the Sta r Lake area, the metavolcanic , Star Lake pl uton, and heared mafic dikes have retained their original igneous 81 80 values. The 81 80 value of quartz from mi neralized veins vary by I per mi! and range from+I0 to+IJ. The only quartz ample having a 81 80 value outside th is range came from a vein not associated wi th a dike or gold mineralization . Quartz from the Star Lake pluton has identical 8180 value to the qua rtz from mi neralized vei ns which suggests that the vei ns and the pluton are related to imilar proces es. The diffe rence in 81 80 values between mi neralized and barren vein may erve a a potential exploration tool in this area. Because o34S val ues of a limi ted number of amples of pyrite from gold-bearing quartz vei ns at Star Lake correlate directly with gold content. the gold may have been syngenetic with the su lphur and the 834 value may be useful for exploration . 8180 values of co-existing quartz, calcite, and amphibole in the veins from Star Lake indicate that isotopic disequilibrium among the minerals is common, but the val ues also record a high temperature of formation (ea . 500°C) involvi ng a component of magmatic fl uid. TheoD value of hydrou mineral from Star Lake retain their original igneous values but whole rock values are generally much lower, an effect attributed to interaction of the minerals with a late meteoric water. In the Fl in Flin-Amisk Lake area, auriferou and barren quartz veins formed from a mixture of hydrothermal and metamorph ic flu id at lower temperatures (ea . 350°C) than those at Sta r Lake. Becau e there i no apparent correlation between 8180 values of the quartz with gold content or relative age of the vein , nor between the 834S val ues of pyrite and gold content, table isotopes appear limited as an exploration tool in the Fl in FlonAmisk Lake areas.

Jan 1, 1986

By A. Aaltonen, S. Paloranta, H. Myllykangas

A property based dynamic model of flotation was built and validated for training purposes. The model is based on the work of the AMIRA P9 project. The recovery of each particle with composition and size is calculated in a given simulation step. The model takes into account machine and operational parameters such as air flowrate and froth height. The model was created using fullscale test data on Pyhlisalmi Cu-Zn-pyrite ore with flotation kinetics of multiphase particles determined. Simulation and validation shows that model can predict the dynamic behavior of the process accurately enough for training purposes.

Jan 1, 2009

By P. D. R. Maltby

This paper describes the background and markets for calcium carbonate and silica sand in Canada, as well as the results of recent test work carried out at the Ontario Research Foundation. Tests on sericite, tremolite, vermiculite, barite and graphite are also mentioned.

Jan 1, 1979

By C. S. Parsons

Introduction Up to the present, the operation of small mills for the treatment of gold ores has not been favoured in Canada to the extent that it has in other countries. For instance, a list of the operating properties in Southern Rhodesia, published in The Rhodesian Mining Journal of November, 1934, shows for the month of September, 1934, that there were over 500 small mills treating less than 50 tons per day, and the majority of these between 5 and 25 tons. They are operated by individuals, syndicates, and small mining companies. It is presumed that the operations are profitable, although from the published figures of the tonnages treated and the yields, it is difficult for one familiar with Canadian operations to understand how this can be possible, in the majority of cases. Most of these small mills employ stamps with plate amalgamation and with, occasionally, tables to produce a concentrate. Enquiries have been received from many parts of the world respecting milling practice suitable for small gold mines and the type of plant used in Canada. The tenor of these enquiries leaves the impression that the majority of the writers assume that the practice would be similar at all small properties. This, of course, is not the case. Conditions vary widely, and what would be a suitable mill for a typical Nova Scotia ore would not necessarily be wholly adaptable to many ores in Ontario, Quebec, or British Columbia. This paper has been written with the intention of inviting discussion, and it is hoped that, by such discussion, the subject will be more fully dealt with than has been possible in the time at the disposal of the writer. Only more or less standard principles and practices have been dealt with, and, purposely, no reference has been made to plants using mills of the Hadsel, the Nutt, or the Gibson type. As there is available but little reliable information on the costs of installation and operation of small mills, it is also hoped that those contributing to the discussion of milling practices for small mines will be in a position to give these data for the benefit of those contemplating the erection of small plants in Canada. Although it is difficult to generalize, it can be said that there are three types of gold mills commonly used at small mines: (1) Amalgamation and Gravity Concentration; (2) Amalgamation and Flotation; and (3) Cyanidation.

Jan 1, 1935

By Mi, Dong Liang, Jingyuan Bai, Victor Zhou, Xujun

Squirrel cage induction motors are the mostly used motors at present. Currently, the rotors of the squirrel cage induction motors are produced by aluminum die casting technique with the advantages of low cost of rotors. It is well known that the copper’s electrical conductivity is around 40% higher than that of aluminum. If copper is used to replace the current widely used aluminum in rotors, the total loss of motors will be reduced, hence increasing the overall motor efficiency. Copper rotors can be used to produce high efficiency and even super premium efficiency motors without enlarge the motor frame size. Considering the huge quantity of motors, the die casting process is the best solution to produce copper rotor with economic cost. Because of the characteristics of copper, it is difficult to produce copper rotors by casting similar to that done in aluminum rotors. In order to improve the die casting quality of copper rotor, a new tooling structure was developed and the casting process of copper rotor was simulated and analyzed by Any-casting software. The filling process, solidification process, inner gas distribution and residual melt modulus were analyzed. It was found that the design of symmetrical runner and inner runner on both sides was helpful to reduce the impact of molten copper to the cavity surface during the filling process. The use of Slag traps array can reduce die casting defects inside the end rings. That will be helpful to improve the rotor quality. INTRODUCTION Squirrel-cage AC induction motors are most widely used in the world. In 2017, the total installed capacity of AC motors in China has reached more than 1.2 billion kW, and the annual power consumption accounts for about 60% of the total national electricity consumption. To improve the efficiency of squirrel-cage motor will be helpful to energy conservation and environment protection. There are several ways to improve efficiency of induction motors, using copper rotor is one of the most effective solutions. It is well known that the copper’s electrical conductivity is around 40% higher than that of aluminum. If copper is used to replace the current widely used aluminum in rotors, the total loss of motors will be reduced, hence increasing the overall motor efficiency. Copper rotors can be used to produce high efficiency and even super premium efficiency motors without enlarge the motor frame size.

Jan 1, 2019

By C. Cutts, K. Wheatley

The Dragon Lake Zone (uranium prospect) comprises a N160º trending vein that is approximately 110 m long, up to 5 m wide and from 1 to 40 m high. The zone is mostly within altered sandstone of the Fair Point Formation, the basal unit of the Paleoproterozoic Athabasca Group, but it also extends downward (up to 3.5 m) into basement rocks that occupy the northerly trending Maybelle River Shear Zone (MRSZ). This subvertical shear zone separates graphitic paragneiss and weakly deformed granitoid rocks to the east from non-graphitic paragneiss and foliated granitoid rocks to the west. The Dragon Lake Zone cuts across both the MRSZ and N060º-N070º-trending cross-faults that offset the shear zone but not the mineralized vein, which contains values up to 54.5% U over 50 cm core length. Strong chloritization occurs in graphitic paragneiss and sandstone adjacent to mineralization. Silica was depleted from the basement rocks and redeposited at the borders of the 5-15-m-wide alteration zone, as well as within overlying sandstone of the Manitou Falls Formation. There are minimal alteration effects in the overlying Lazenby Lake Formation. Geochemistry shows that the alteration zone in the Fair Point Formation is highly anomalous in metals, most notably in Ni, As, U, Pb, Co, and B. Clay within this zone is illitic and Fe-rich chlorite is also present. Brittle deformation is not as widespread or as well developed in the Fair Point Formation as it is in the overlying Manitou Falls Formation, which is extensively brecciated and contains some anomalous metal values.

Jan 1, 2013

By E. L. Bruce

Red lake is a body of water some thirty miles in length lying about forty miles northwest of the outlet of Lac Seul. It forms one of several large lake expansions on a river which enters the English river from the north, twenty miles below Lac Seul. Before the construction of the National Transcontinental railway a long canoe journey was necessary to reach that part of the English river, and Red lake, two days travel beyond, was one of the furthest outposts of the trading companies in that difficultly accessible triangle of country between Lake Winnipeg, James Bay and the English and Albany rivers. The Hudson's Bay Company post at Red lake is said to be one of the earliest established in the district but there are no records at the post, and as the English and Albany rivers never were used to any great extent as travel routes there is no mention of the place in the diaries of any of the early explorers. Dr. Bell passed through Red lake on his excursion to the Berens river country in 1883, and a brief note mentions that Huronian rocks were seen. To Dr. Dowling, however, belongs the credit for the first thorough description of this basin of sediments and basic volcanics. In 1893 he followed the course of Dr. Bell's trip, of ten years previous, through Red lake to the upper part of the Berens river.

Jan 1, 1926

By T. H. Etsell, P. Kerr, Qi Liu

"The objective of this investigation was to study the reaction mechanisms during the reduction of iron oxides in the presence of calcium chloride and carbon black as a simplified iron segregation process. The gas phase was analyzed by mass spectroscopy and the solid reaction products were analyzed by scanning electron microscopy. Mass spectroscopy, combined with thermogravimetric analysis and differential scanning calorimetry, revealed the presence of several gases at elevated temperatures over time, and the scanning electron microscope in combination with energy dispersive X-ray analysis illustrated the growth of a metallic iron phase on or near the carbon substrate. The results correlated well with similar copper and nickel segregation processes, but also introduced new insights that challenge the simplicity of the current models. The formation and transport of gaseous iron species to the carbon substrate in the presence of steam and hydrogen were evident during the reduction process that was studied; however, there is more happening at a mineralogical level, based on evidence of a liquid phase resulting in substantial growth due to an apparent fluxing effect created by the calcium chloride.These results help to better explain the chemical reactions and, in turn, the thermodynamics and kinetics of iron segregation processes related to the beneficiation of low grade complex iron ores. The results are also applicable to the production of metallic iron and concentrated titanium dioxide from ilmenite ores. The benefit of this process is that it allows ores in which the iron minerals are intimately associated with gangue minerals to be processed in circumstances where conventional mineral processing techniques are unsuitable or incapable of upgrading the material."

Jan 1, 2016

By T. G. Joseph, M. Bolster, M. Curley

"High tirerim loading on haul trucks operating on rough ground frequently manifests as mechanical separations and rim base cracking caused by cyclic fatigue. This paper provides an understanding of the impact of high loads on rim component life and tire footprint, bulge, and deformation behaviour; and develops a maintenance planning tool to predict strain implications of high g loading for a given rim location. Loading tests and analyses were conducted for a tirerim arrangement under increasing load and internal tire pressure. Graphical models were developed, allowing higher g load extrapolation predictions for specific rim components.KEYWORDS g load, Mining, Model, Prediction, Rim, Strain, Tire bulge, Tire footprint, Ultra-class vehicleRÉSUMÉ L’application d’un chargement élevé sur le système pneu/jante de camions de transport rou¬lant sur des terrains accidentés se manifeste fréquemment par des séparations mécaniques et une fissure à la base de la jante engendrée par une fatigue cyclique. Cet article nous permet de mieux comprendre l’incidence de l’application de charges élevées sur la durée de vie des composantes de la jante ainsi que sur l’empreinte, la hernie et le comportement de déformation des pneus. Il développe également un outil de planification de l’entretien visant à prévoir l’incidence des contraintes en cas d’application d’un chargement g élevé sur un endroit donné de la jante. Des essais et des analyses de la charge ont été effectués pour un agencement pneu/jante soumis à une charge et une pression interne du pneu croissantes. Des modèles graphiques ont été développés, ce qui a permis d’établir des prédictions sur la base d’une extrapolation du chargement g plus élevé appliqué à des composantes spécifiques de la jante.MOTS CLÉS charge g, contrainte, empreinte du pneu, exploitation minière, hernie du pneu, jante, modèle, prédiction, véhicule ultralourdINTRODUCTION The purpose of this paper is to report on a proposed and trialed tire performance test based on data obtained from controlled testing that is used to predict the impact of high g loading on hauler rims and tires with greater accuracy. For example, for many years oil sand mining operations have expressed qualitative beliefs that an impact load of the magnitude experienced by a rim and tire arrangement is not detrimental to a rim as a stiff component; however, mining equipment components are subjected to cyclic loading where failure can result from repeated load/unload activity, truncating the peak region of a stress–strain response and resulting in fatigue failure at a stress value that is less than the peak value. The outcome reported by oil sand haul truck maintenance groups indicates they have realized that most high g impacts—such as those experienced by hauler tires and rims operating on poor ground conditions—can result in failure due to cyclic loading, where higher loads require fewer cycles for failure. This high-level loading and the resulting strain transmitted to the rim is evident in the results of the laboratory testing presented in this paper."

Jan 1, 2019

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 B. N. Nandi

This paper is a study of the application of the science of coal petrology to the use of coal in the iron and steel industry. The petrography of coal is given the most attention, with some mention of coal palynology. The history of the petrographical analysis of coal is first out-lined, with a description of the various coal entities, and then the apparatus and experimental techniques employed for coal evaluation are discussed. The coke stability factor and the relation of coke strength to petrographical data are also covered, and some space is given to the new science of coke microscopy, in particular its use in following the oxidation of coals.

Jan 1, 1966

By K. J. Boser

"Medium Voltage (MV) metal clad switchgear is referred to as the voltage class from 2.4 kV to 38 kV. Technological advances in circuit breaker designs over the last 20 years have given rise to retrofit options in lieu of complete replacement for older outdated circuit breaker technology. This paper examines the four MV breaking techniques that exist in industry and investigates various retrofit versus refurbish options for switchgear modernization and life extension. IntroductionThe life extension and upgrade of medium voltage circuit breakers is becoming an increasingly important issue in today’s modern industrial facilities from both a reliability and safety standpoint. Unscheduled downtime, loss of production, and plant safety issues are just some of the concerns that need to be addressed with aging switchgear. A thorough examination of the available breaking mediums allows an informed decision to be made when the time comes to assess equipment performance. If you look back over the history of medium voltage breakers, you will find that there have been four breaking techniques developed and widely used:• air magnetic;• minimum oil;• vacuum; and• SF6.Many facilities that were constructed 25 to 30 years ago relied on air magnetic or minimum oil circuit breakers in their distribution systems. At the time, these were the only “tried and tested” options and they afforded good service. Since then, however, newer technology has given us the vacuum and SF6 mediums which have both proven their reliability and monopolized the market. All the methods have their particular place in industry and what follows is a summary of the advantages, disadvantages, and chronological development of each breaking technique."

Jan 1, 1998

By A. Roy MacLean

"In the Maritimes, there are twelve coal areas. From east to west, these include the Sydney coal field, the St. Rose - Chimney Corner, Inverness, Mabou, Port Hood, Pictou, Colchester - Debert, Springhill, Joggins - Chignecto, Beersville, Lake Stream, and Minto. The first eight are in Nova Scotia while the remaining four are in New Brunswick.In all these areas, the coal was formed during the Carboniferous period, which existed some 300 million years ago. However, within this period not all coal formation took place during the same time. There were three main intervals, which occurred at the time that the Riversdale, Cumberland and Pictou groups were laid down (Hacquebard, 1970). The oldest coals are those of the Riversdale Group. These coals were of rather limited extent, and only a few mineable seams are present, particularly at St. Rose -Chimney Corner and Port Hood. From these two areas only 2 M tons have been extracted, and 'measured' resources of 7 and 9 M tons respectively remain. The Cumberland Group coals are confined to Cumberland County and include the coals of Springhill and Joggins River Herbert -Chignecto. Some 43 M tons have been removed and only 7 M tons of 'measured' coal remain, with an addit10nal 39 M tons of 'inferred' resources. However, there are additional resources at Springhill, which will be discussed in more detail in a later section. The coals of the Pictou Group are the youngest and the most abundant, both in actual number of seams and in regional distnbution. These coals were formed during the Westphalian C and D, a time during which the main coal deposition in Europe also took place. Here belong the coals of the Sydney, Inverness, Mabou, Pictou, Debert, Beersville, Lake Stream and Minto fields. Their total production amounted to 469 M tons or 91 % of the Maritime total of 514 M tons. The remaining resources of all Pictou Group coals have been calculated at 254 M tons of 'measured' coal and 949 M tons of 'inferred' coal. As can readily be seen, the bulk of both past production and remaining resources occur in the Sydney coal field. The Sydney figures represent 73% of total production, and 87% of total 'demonstrated' resources in the Maritime Provinces. Next to Sydney, the Pictou coal field has been the greatest producer, with 59 M tons; it also has the second largest 'measured' resources, amounting to 25 M tons. However in terms of 'inferred' coal resources, the Mabou coal field, ~ith 140 M tons, ranks second to Sydney."

Jan 1, 1985

By Xiaozhu Chen, Qi Ping, Pu Yuan, Qinyong Ma

"In order to investigate the fractal feature of coalmine deep rock fragments under impact loads, variable cross-section split Hopkinson pressure bar apparatus, 50 mm in diameter, was adopted to conduct impact compressive test for rock specimens from -962m deep coalmine. Various impact pressures, such as 0.3, 0.6, 0.9 and 1.2MPa, were selected to implement different loading rates. Sieving statistical analyses were conducted for rock fragments after being impacted, and the particle size distribution of broken rock in various loading rates were calculated with the fractal method and then the corresponding fractal dimension was obtained. Test results shows that there is a good self-similarity and fractal feature in fragments distribution of deep coalmine sandstone under impact loads. The fractal dimension of fragments is between 1.9 and 2.7. The research also indicates that there is an approximate power relationship between dynamic compressive strength and fractal dimension, and a strength power relationship between fractal dimension and average strain rate. Moreover, there is a linear relationship between fractal dimension and specimen absorbed energy. The rock fractured process can be quantitatively described through fractal dimension, which can reflect the deep rock broken degree and is an ideal index to evaluate the distribution of rock fragments.INTRODUCTIONBroken rock is one of the most basic processes in mining operations, rock fragmentation has always been an important index to evaluate rock breaking effect (Xu & Yu, 1984). Macroscopic fragmentation of rock material is the final results of continuous development, expansion, gathering and cutthrough of internal micro-cracks. This process, developing from microscopic damage to macroscopic fragmentation, is an energy dissipation process and shows fractal characteristics (Xie, 1993). Turcotte (1986) has conducted statistical analyses of fragmentation for different kinds of geological materials under various broken conditions, and arrived at the conclusion that fragmentation distribution is a fractal."

Jan 1, 2015

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 Rita Awwad

Building Information Modeling (BIM) has been gaining a significant edge in the construction industry over the last decade. BIM allows gathering all building information in one shared database that can help all construction entities better understand, integrate and visualize all work progress from inception to operation of the building. The main purpose behind BIM is to bring all project participants together (Client, Architect, Contractor, Consultant) since the initial stages of a project allowing them to cooperate and work as a team in the promise of an increased productivity, reduced cost, enhanced quality and faster delivery. However, a full-fledged implementation of BIM tools and benefits is not yet achieved in the construction industry and remains a debatable issue for researchers and practitioners in the construction field. This paper aims at assessing BIM awareness and usage in the Lebanese construction industry through conducting interviews with contractors, architects and consultants that are key players in the Lebanese market. A comprehensive literature review about BIM adoption in some developed countries and in the surrounding region is also provided in order to better evaluate the Lebanese industry status in comparison with foreign industries. This research sheds the light on BIM awareness of the different construction parties in the Lebanese market, assesses the extent of its current use, identifies the pertaining implementation challenges, and provides recommendations to enhance BIM role in the Lebanese construction industry.

Aug 1, 2013

By J. Ji

Oxygen requirement during acidic pressure oxidation of sulphide concentrates can he as high as 800 kg/(m3.h) in the first compartment of an autoclave when the total oxidation residence time is shortened to 30 minutes. To achieve such a high oxygen transfer rate while maintaining satisfactory oxygen utilization, a pilot plant campaign was launched at the Placer Dome Research Centre in 1998 to measure the oxygen mass transfer coefficient in a 5 m3 pressure vessel at a total pressure close to 500 psig with a 30 HP gassing agitator. Maximum oxygen flowrate to the pressure vessel was designed at 3 600 kg/h. In this paper, a great deal of information is provided on the gassing agitator, pressure vessel. measurement procedure and results. Without oxygen sparging, the oxygen mass transfer coefficient is 2 600 h-1 with a mixing power input of 5.0 kW/m3 in solution. With oxygen sparging, the oxygen mass transfer coefficient increases to 3 500 h-1 with a mixing power input of 4.0 kW/m3 in solution.

Jan 1, 2004

By J. E. Dutrizac, J. M. Zinck

Ferrihydrite is often the initial precipitate resulting from the rapid neutralization of Fe(III) sulphate solutions, and it seems to be a major constituent of zinc plant neutral leach residues. The most important parameters affecting ferrihydrite precipitaton are temperature, solution pH and the neutralization rate. Low temperatures and rapid neutralization rates yield poorly filterable ferrihydrite, whereas higher temperatures and slower neutralization rates produce readily filterable precipitates; in all instances, however, the precipitates are two-line ferrihydrite. Significant amounts of Zn are incorporated in the ferrihydrite precipitates, and the Zn contents increase with increasing Zn concentration, pH or temperature. Generally, the sulphate contents of the precipitates decrease as the Zn contents increase, and this may indicate that the Zn is adsorbed on the ferrihydrite. Discrete Zn phases were not detected. Neither Cd nor Tl is precipitated with ferrihydrite, although thallium jarosite co-precipitates with ferrihydrite at high Tl concentrations and elevated temperatures. Virtually all of the Sn added to the solution precipitates with the ferrihydrite, but the tin is believed to be present as intimately admixed amorphous SnO2.nH2O. Although selenite extensively precipitates with the ferrihydrite, selenate remains mostly in solution, likely because of the close similarity of the SeO4 2- ion to the SO4 2- ion which is present in high concentrations and saturates the available sites for anion adsorption.

Jan 1, 1998

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 Jesús L. Valenzuela, José R. Parga, Salvador Aguayo, Héctor Moreno

The Merrill Crowe zinc-precipitation process has been applied worldwide on a large number of operations for the recovery of gold and silver resulting in a higher consumption of zinc dust from cyanide solutions. However, in some of plants this precipitate is of low quality, because lead, cadmium and especially copper are precipitated along with gold and silver. The low quality precipitate also requires more fluxes in smelting and shortens crucible life. In this study, a process is introduced to remove copper, silver, lead and cadmium from barren solutions following the Merrill-Crowe process. Copper and silver are removed by precipitation in a serpentine reactor, using sodium sulfide as the precipitator, and sulfuric acid for pH control. The recovery of lead and cadmium ions with natural hydroxyapatite using cow bone powder (CBP) as a new adsorbent material, is introduced. CBP is capable of removing lead and cadmium ions from aqueous cyanide solutions with 99% efficiency. It has the ability to compete with other existing commercial adsorbents for the removal of lead and cadmium. Results show that pH value has a significant effect on copper cyanide removal efficiency, and it was determined the optimal pH range to be 2 - 3. At this pH value, the copper cyanide removal efficiency achieved was up to 99 %; and for the cyanide associated with copper cyanide complexes, the recovery was 90%. Finally, the precipitate quality was improved 400% .This procedure was successfully run at three mines in México.

Jan 1, 2014