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By J. C. Marchand, M. A. Berube

"L'objectif principal recherché lors du broyage d 'un minerai est de libérer adéquatement ses valeurs utiles en vue de leur concentration ultérieure. La pratique courante consiste à tenter d'obtenir un produit de broyage d'une granulométrie constante. Malheureusement, les propriétés texturales des minéraux utiles varient naturellement dans un gisement et une telle stratégie n'entraine pas toujours pour ces minéraux un degré de libération constant. Pour un rendement optimal du procédé de concentration, cette variable très importante doit donc être périodiquement vérifiée.Jusqu'à maintenant, la plupart des études de libération des minerais se font en examinant des sections polies de particules du minerai broyé. Le GRAAIM a récemment assemblé un système modulaire d'analyse d'images qui servira en grande partie à des mesures automatiques du degré de libération des minéraux. Le système s'avère relativement peu coûteux comparativement à la plupart des analyseurs de texture conventionnels si l'on considère que plusieurs de ses composantes, par exemple le miniordinateur, sont utilisées à une foule d'autres applications, et il permet de plus une grande souplesse d'utilisation puisque l'on a qu'à construire des algorithmes de mesure et de calcul en fonction de l'objectif recherché. Des programmes particuliers permettant des études automatiques de libération sur des sections polies de particules ont ainsi été élaborés. Ils permettent également des mesures de teneurs et de distributions granulométriques apparentes des particules. Des résultats obtenus dans le cas de minerais de fer sont brièvement présentés afin d'illustrer la technique."

Jan 1, 1983

By J. ?H. Chen

Remote sensing technologies have been applied to numerous fields and already benefited those in improving efficiency and recognition accuracy. Change of streamflow can be devastating to residents living along riversides. Still it is difficult to detect such deathly change in large area scale by traditional field surveys. The research aims at provision of detecting streamflow change using a mathematic method based on remote sensing technologies. The scope is on remote sensing stream images taken during the invasion by Typhoon Morakot, bringing one of the major catastrophes to Taiwan. An algorithm was adopted to deal with streamflow recognition on RGB images. The algorithm is capable of yielding change measured by meters and illustrates how main streams shift. An practical example for the Baolai area surrounded by Laonong stream shows that the streamflow moved 88 meters (36 pixels) toward the downtown area during the invasion by Typhoon Morakot. In addition, the results highlight all dangerous zones (scouring zones) for residents to prevent further potential damage.

Aug 1, 2013

By E. Krause

The oxidation of Fe(II) with S(IV) and oxygen can be used advantageously in leaching systems requiring both Fe(III) and sulfuric acid; e.g., heap leaching of sulfide-containing ores or concentrates. The oxidation of Fe(II) with SO2/air is several orders of magnitude faster than with air alone; rates of up to ?20 g/L'h were observed at 25°C. The reaction proceeds via an intermediate orange-red mixed-valence Fe(II)/Fe(III) sulfite complex, which is present at an essentially constant concentration throughout most of the oxidation process. The oxidation rate of Fe(II) is approximated by the formula -d[Fe(II)]/dt = k [S(IV)] [02]0'3. The concentration of the mixed-valence complex, and thus the iron oxidation rate, decreases with increasing acidity. Certain impurities, such as SCN- and thiourea, negatively affect the rate. The oxidation reaction 2Fe2 + SO2 + 02 4 2Fe3+ + S042- is accompanied by the side reaction H20 + SO2 + 1/202 4 H2SO4. The side reaction becomes particularly important at low temperatures and whenever the oxygen mass transfer is insufficient with respect to the rate of addition of S(IV). Thus, effective oxygen mass transfer is essential for achieving high oxidation rates with minimal acid formation. The activation energy was estimated as 141 kJ/mol over the temperature range 10-35°C.

Jan 1, 2006

By Frank Arthur Forward

FRANK ARTHUR FORWARD was born in Ottawa and attended the University of Toronto, where he received a B.A.Sc. in chemical engineering in 1924. From 1924 to 1929, he was a smelter operator and research metallurgist with the Consolidated Mining and Smelting Company of Canada Ltd. (Cominco) at Trail, B.C. Moving to Australia in 1929, he was assistant smelter superintendent, Mount Isa Mines Ltd., Queensland, until 1934, when he returned to Canada, spend-ing one year as metallurgist with B.C.

Jan 1, 1970

By H. Attia, S. Engin

This paper presents a practical approach for determining the optimal spindle speed and the depth of cut in a milling operation within the ever-increasing economic and technical constrains. Analytical modeling and experimental work has been carried out to predict chatter in such operations. The stability lobes determined from this analysis were then used as a constraint in the optimization of the cutting process. The optimal cutting conditions are determined for two different objectives: maximum metal removal rate and minimum cost per unit. It is demonstrated that this approach can be generalized to impose multi-level constrains, e.g., surface integrity and machining accuracy. The approach presented in this work was examined and validated on three NC milling machines. The productivity improvement, cost reduction, while respecting part quality requirements, is demonstrated.

Jan 1, 2006

By Chuan-liu Wang

The bionic non-smooth surface has the characteristics of anti-wear, and reducing resistance. Based on bionic non-smooth surface?s characteristics, a bionic drill bit was developed. When the bionic drill bit is used, a bionic non-smooth surface forms on the crown of bionic drill bit. This surface can be used to extend the life of drill bit and improve drill efficiency. The bionic unit diameter and arrangement were researched in this paper to determine the optimal bionic non-smooth surface for further improving the life and efficiency of drill bit. Four bionic samples having the same structure size, materials and arrangement were designed and manufactured. After being sintered, the abrasion ratios of the four bionic samples were tested, and the results show that the abrasion ratio of Nos. 3 and 2 were similar (only 2% difference) and higher than that of No. 1 and 4. Therefore, the optimal diameter of bionic unit is 1.5 and 2.0 mm. Small diameter bionic drill bits were designed and manufactured, and tested in the laboratory. The results show that not all bionic structure bodies are better than normal diamond bits, except the bionic unit arranged in a reasonable range. When the angle was 24° and 30°, the arrangement of bionic unit were more reasonable, which shows the superiority of the bionic coupling bit.

Aug 1, 2013

"2.1. General Considerations and Properties2.1.1. IntroductionOur present knowledge of the platinum-group elements (POE) is extensive, the reason being two-fold. The elements have many uses and, moreover, they exhibit extremely varied chemical behaviour, depending on their state of oxidation and chemical environment. The present chapter reviews a selected body of material which is of particular relevance to mineralogy and geochemistry.Comprehensive treatises on the POE include those by Mellor (1956-1957), Gmelin (1938-1957) and Pascal (1958). The inorganic chemistry, particularly coordination chemistry, has been dealt with in works by Griffith (1967), Hartley (1973) and Livingstone (1975), and the analytical chemistry by Walsh and Hausman (1963), Beamish (1966) and Beamish and Van Loon (1972, 1977). Darling (1973) and Savitsky (1978) have reviewed the metallurgical properties and applications of the metals. Goldberg and Helper (1968) have reviewed the thermochemistry and oxidation potentials of POE systems, and Wagman et at. (1969) have also provided selected values of their thermodynamic properties. The geochemistry of the POE has been reviewed by Yushko-Zakharova et at. (1967), Cousins (1973), Cabri (1974), and Naldrett and Duke (1980).Platinum was used briefly as a coinage metal in ImperialRussia. Otherwise, the principal early use for platinum and its alloys was in the fabrication of chemically resistant apparatus. Subsequently, a large part of platinum production was utilized for catalysts in the sulphuric acid and ammonia industries. Platinum has been replaced by vanadium pentoxide in the manufacture of sulphuric acid, but, in recent times, catalytic upgrading of petroleum and emission control systems for automobiles have opened further huge markets for the metal. All of the POE find uses either as reagents or catalysts in the synthesis of organic compounds, e.g., in the Wacker process, which uses palladium chloride to catalyze the production of acetaldehyde from ethylene. There are, of course, a large number of specialized uses for the elements, particularly in alloys, temperature measurement devices, cancer therapy and so on."

Jan 1, 1979

By M. H. Allan

"This paper presents the geographic and geological setting of Saskatchewan Power Corporation's Poplar River Mine in south-central Saskatchewan, about 8 miles from the U.S. border. Generally the mine, which is being expanded to four million tons per year, is in an extremely disturbed geological area with severe dewatering problems. The lignite coal, which is strip mined, is supplied directly to an electric power generating station by means of a 7-mile unit-train private railroad.A number of unique reclamation and socio-economic problems were encountered because of the proximity to the U.S. border and because of the lack of experience of the regulatory authorities in projects of this kind. These are described in some detail, as well as the performance of one of the largest draglines in Canada. IntroductionThe Saskatchewan Power Corporation is a publicly owned utility which has the franchise to supply electricity and natural gas to all customers within the boundaries of Saskatchewan.Saskatchewan is a province which can almost be divided in two: the populated southern portion, principally devoted to farming, and the northern portion which is mostly on the Precambrian Shield and consists of lakes, rocks and muskeg. This portion is largely uninhabited except for a number of small villages. However, in the last few years there has been considerable mineral exploration and development, notably for uranium. This has helped considerably in the diversification of the basic agricultural economy of the province.Saskatchewan consists of 251,700 square miles, 761 miles north to south and an average of 335 miles east to west. It has a population of approximately 960,000, giving a population density of four persons per square mile. The Saskatchewan Power Corporation supplies 357,249 electrical arid 221,378 natural gas customers."

Jan 1, 1982

By C. Cortés

Flotation is a highly interactive process where a change or disturbance in any part of the circuit results in different final grades and recoveries. This high variability of the circuit metallurgical performance complicates the diagnosis of the scavenger stage at the end of the line, as copper losses in the final tailings are erratic and not totally a consequence of problems in the scavenger section. The assessment of the scavenger performance requires a more elaborated procedure than that used for others stages of the circuit. This communication describes the application of an approach that combines results of laboratory flotation tests with those of surveys performed at the plant. The approach is based on running surveys in one of the circuit lines to collect samples for determining grade vs. recovery curves for total mass and size-by-size fractions. Full mineralogical and liberation analyses are also considered on some samples of the feed and tailings streams selected to have a range of feed grades. A separate sample of the feed is used to run laboratory flotation tests to determine optimum flotation time. Two additional pieces of information are the effect of operating variables on recovery, determined through a test program based on design of experiment techniques, and operational data on every cell in the line gathered by visual observation. The application of this approach to one of the scavenger lines at Los Colorados concentrator (Minera Escondida, BHP Billiton) is demonstrated.

Jan 1, 2007

By C. P. Browning

Copper, as far as we know, was the first metal used by man, and due to the fact that it occurs in many places in the 'native' state, and also to the ease with which it may be shaped, it has played an important part in the evolution of civilization. Copper tools with inscriptions dating back to 6,000 B.C. are known in Egypt, where the metal probably got its start as a useful material in human hands. Just how far back the use of copper in Canada dates is difficult to say, but it was in use by the Indians in the Lake Superior country long before the arrival of the first white man. For many generations the Eskimos also have used copper derived fr0m deposits of the native metal found in the Coronation Gulf district. Due to the metal's many unique qualities, imperishable with age, ancient implements and utensils are apparently as good today as when they were made, having withstood the onslaught of time probably better than objects of any of the other base metals. Copper alloys so well with other metals that today it is second only to iron in its industrial value. Even at the beginning of the eighteenth century the world's production of copper was probably not more than seven thousand tons a year, with Great Britain producing three-fourths of this. One hundred years ago the mines of the United States, Chili, Mexico, Canada, South Africa, Australia, and Tasmania, which now produce about nine-tenths of the copper of the world, were totally undeveloped. Ln 1926 the world production of copper was approximately 1,658,000 tons, which was seventy thousand tons greater than in the preceding year; but growing demand absorbed the increased production, so that the stock of rough copper throughout the world is comparatively small. Of this huge tonnage of the metal, Canada produced four percent, two-thirds of it emanating from British Columbia, nearly one-third from the Province of Ontario, and the balance from Quebec.

Jan 1, 1927

By J. L. Nebreda, Z. Fan, J. B. Patel

"A380 alloy has been widely employed to produce thin-wall components via high pressure die casting (HPDC). During HPDC processing, there is a significant problem of property variation even with the very stable and precision automated casting procedure. The enlarged variation lowers the component performance and affects the steady and uniform property distribution along the whole component. In this study, high shear melt conditioning technology was developed and applied to the melt prior to pouring into the shot sleeve. Experimental results show that with application of intensive melt shearing, the variation of elongation was decreased from 21.8to 13.9%, and yield strength variation was reduced from5.5to 3.6%. The improved property variation is attributed to enhanced nucleation both in shot sleeve and the die-cavity, and to the improved distribution of porosity and secondary phases as a benefit of high shear induced grain refinement. With application of high shear, large number of the Spinel phase (MgAl2O4) particles with double size distribution in average diameter of 80and 300nm were formed. Due to the good orientation relationship and small misfit between alpha Al and MgAl2O4, the particles act as the effective nuclei in shot sleeve and die cavity, respectively.INTRODUCTIONA380 alloy had been widely used for produce automotive components by cold chamber high pressure die casting(HPDC) processing, due to its relative good mechanical properties and cast ability performance, and more important most of A380 ingots were produced by recycled Al alloys. Therefore, to promote utility of A380 will contribute to reducing emission of CO2and to the lightweight of automotive industry as well. When cold chamber HPDC was employed to produce the components, the mechanical properties of A380 alloy always have a distribution range (named variation herein), or in other words the properties were not stable. The reason was ascribed to the typical solidification characteristics occurred in HPDC processing. During HPDC processing, there are three steps of melt movement. The first step is that the melt was poured into shot sleeve at temperature of about 680°C, in which shot sleeve was preheated by few shots of melt filling, or by heater. During step one, the first solidification of melt was happened in shot sleeve and about 20% solid made of coarse a-Al grains was formed(Li, Xiong, & Guo, 2016).Such kind of grains will retain in the final products and deteriorate the properties variation. The second step is that the melt was forced moving forward slowly by plunger at about 0.2–0.3m/s until the liquid melt front to the inner gate of mold. The third step is that the melt moved very fast to complete the filling of die cavity and refilling the solidification shrinkage by fast movement of plunger about 2–3m/s. The second solidification was occurred in die cavity and fine a-Al grains will be formed by high cooling rate at about 500–1000°C/s. From the solidification point of view, the grain size was dominated by nucleation and growth. When HPDC was employed to produce components, the melt quality becomes the priority factor to control the solidification process as the other casting parameters were kept at the same."

Jan 1, 2018

By C. V. Deutsch, O. Babak, J. G. Manchuk

High levels of geological heterogeneity occurring over relatively short distances pose a challenge to the unconventional open-pit techniques used in oil sands mining. There is strong motivation to mine selectively and minimize dilution and loss; however, the large equipment and high mining rate used to meet production targets tend to reduce selectivity. A numerical model is developed to account for geological complexity, mining equipment, regulatory criteria, and other operational parameters. This framework is used for more accurate forecasts, optimization of equipment, and other operational decisions. An example demonstrates the approach in light of Alberta Energy Regulator criteria.

Jan 1, 2014

By Paul Delottinville, Maynard Hall, Henry Hillier

"An expert system application for supervisory control and optimization of the indurating process at the Iron Ore Company of Canada (IOCC) has been developed and installed in closed-loop. Prior to the installation of the expert system, the indurating machine was rebuilt and the instrumentation revamped. A Foxboro I/A Distributed Control System (DCS) was installed for regulatory control, and a new control strategy configured. The modernization of the regulatory control has resulted in significant improvement in both production rate and product quality. Expert system control was implemented in September 1996. Preliminary indications are that the expert system has further improved the consistency of product quality, enhanced fuel efficiency and increased productivity. The expert system considers both wet and dry sections of the circuit, and its optimization scheme is driven by pellet tumble index and compression strength. Statistical Process Control (SPC) rules were implemented in the expert system as part of the quality analysis and control scheme. The expert system application was developed and delivered using the Comdale Expert Optimizer (CEO), and has been in continuous closed-loop control since its installation. The system development and implementation is described, and preliminary benefits are presented..... IntroductionIn early 1996 the Iron Ore Company of Canada (IOCC) contracted Comdale Technologies of Toronto to develop and implement a real-time expert system for optimizing the indurating pelletizing furnace at our plant location in Labrador City, Newfoundland.The decision to install the expert system has been timely. Like many other resource-based industries in increasingly competitive markets, IOCC recognizes the need to find ways to improve the efficiency of our production process and ensure that product quality is maintained at the highest levels. With the Labrador City plant producing 11 million tons of iron ore pellets annually, implementing the best technology solutions to meet these objectives is critical."

Jan 1, 1998

Spatial information Critical to a project since it underpins: ?Discovery of mineral resources ?Orebodydefinition and technical assessment ?Mine design and planning ?Profitability and project value Data ?Single most import asset. ?Good interpretation of quality data underpins project growth and success. TEAMWORK

May 1, 2002

By R. P. Townsend

It is a widely accepted "fact" that a Koepe friction hoist is generally the best solution for production hoisting when compared to a double drum hoists. This would appear to be true if one looks at the initial capital cost of just the hoist, and also if one compares the size of the motors selected for the duty. But is this the whole story? What are the longer term costs involved in the hoist's operation, and what are the relative efficiency's of the two designs? Perhaps the Koepe hoist design enjoys a better reputation than it deserves.

Jan 1, 2011

By M. P. Sinha, Rashmi, Tata Steel Ltd., S. Jaiswal, A. Bhatnagar, P. Garg

Reagents form a crucial part of flotation process as they have the power to control the surface properties of minerals. In case of coal flotation, collectors and frothers are two the important and commonly used reagents. But other types of reagents such as promoters, modifiers and depressants are also finding wide applications because of their availability to improve selectivity and increase recovery. Because of these chemicals the scenario has changed from flotation being used mostly for high rank hydrophobic coals to low rank, oxidised or inferior coals. In the present work a case is presented in which two non-ionic surfactants (abbreviated as A & B) known to act as emulsifier have been studied to get a better flotation performance for a preparation plant with varying feed characteristics. Laboratory flotation tests were conducted with both the surfactants using three feed samples of the plant by varying the dosage at three different levels. The highest combustible matter recovery (more than 80%) was obtained for surfactant B at a dosage of 75 ppm (parts per million) for feed 1. But at the same dosage the recovery decreased by 21% and 10.2 % respectively for feed 2 and 3. On the other hand surfactant A showed a consistent result for all the three feed samples giving the highest value at a dosage of 50 ppm followed by a decrease beyond this point. The tests were complemented by contact angle measurements that demonstrated the same trend. In addition to this the reproducibility of data for Surfactant A was checked and found that the standard deviations for both separation efficiency and combustible matter recovery were within the permissible range (less than 5%). Finally an in-plant process optimization study to evaluate the performance and applicability of surfactant A at industrial level was done and has been discussed.

Jan 1, 2016

By J. B. McKenzie

Since connnencing underground prcxiuction in 1979, the Ruttan Mine has been prone to secon:iacy sulphide dust explosions. Al though infrequent during the early years of prcxiuction, these occurrences did result in major damage and lost time injuries. 'As the mine exparrled and developed to further depths, sulphide dust explosions occurred on a more frequent basis. Incomplete ventilation se:rvices, required to exhaust the affected areas, caused frequent delays resulting in lower prcxiuction rates due to the time required to ventilate the affected areas of the mine. CUrrent procedures to minimize the effects of secon:iacy dust explosions evolved from practical suggestions arrl examining methcx:ls other mines have developed to cope with the problem. Procedures and regulations to protect errployees from exposure to hazards of sulphur dioxide are time consuming, expensive and counter prcxiuctive in their present fonn. This paper describes the history of secon:iacy sulphide dust explosions at the Ruttan Mine and the methcx:ls and proced.ures currently in place to minimize and contain the effects of dust explosions.

May 11, 1988

By P. Duran

The metallurgical gas handling system at Chagres Smelter, like that of many smelters, can be the limiting constraint to processing more concentrate through the smelter. Mass and energy balances for the metallurgical gas handling system processing off-gases from the flash furnace and Peirce-Smith converters have been used by both operations and process engineering groups to help evaluate different operational scenarios in which the use of the installed capacity could be maximized and/or an operational strategy can be change with the purpose of removing a bottleneck or justifying an investment to relieve a constraint in the gas handling system. The present work describes the development of these process balances that were carried out in Exce®. The results were validated with operational data and, subsequently, some cases of industrial interest were simulated, detecting some conditions that were limiting the operation due to the present installed capacity in the Chagres Smelter.

Jan 1, 2007

Open pit production planning is a procedure consisting of multiple stages. Although all the planning stages rely on the geostatistical block models, long- to short-term plans each require their appropriate resolutions and levels of details. The main motives behind using different resolutions are the tractability of the models and the practicality of the generated schedules. The current approach in the mining industry is to use nested pits generated by Lerchs-Grossman as the basis for long-term planning and to use manually generated polygons, within those pushbacks, as the units of production control in mid- and short-term planning. However, the nested pits generated by Lerchs-Grossman algorithm and the polygons drawn by mining engineer do not provide control over the value and tonnage of ore and waste inside the planning units and therefore cannot lead to optimum solutions. In this paper, we first present a pushback determination approach which maximizes the profit of the mine with control over the tonnage of ore and waste within each pushback. We then propose a clustering approach with size and shape control that determines aggregates within those pushbacks; and finally, we introduce a mathematical programming model which uses the generated pushbacks and aggregates as the planning basis and generates production schedules that maximize the net present value of the operation and are practical from the operation?s point of view.

Aug 1, 2013

By S. Koski

The Cerro Verde copper-molybdenum porphyry mine, majority owned and operated by Freeport- McMoRan Copper & Gold, is located 30 km southwest of Arequipa Peru. The concentrator, which produces copper and molybdenum concentrates, started operating in late 2006 with a 108,000 tpd design capacity, processing primary sulfide ore (mainly chalcopyrite and molybdenite). Plant capacity was recently increased to 120,000 tpd. The comminution circuit consists of one 60? x 113" primary crusher, four MP-1000 secondary crushers in closed circuit with dry screens, four 2.4m x 1.6m High Pressure Grinding Rolls (HPGRs) in closed circuit with wet screens, and four 7.3m x 11m gearless ball mills in closed circuit with cyclones. The HPGR circuit is fed by the Secondary Crushing circuit product at a T80 of 35 millimeters, and the HPGR circuit product feeds the Ball Mill circuit at a T80 of 3000 microns. This paper describes operating experiences with HPGRs during these first four years highlighting improvements in operating practices and presentation of data regarding operational efficiencies, also discussed are the primary benefits provided by HPGRs such as production of micro fractured particles, reduced ore Bond Work Index, and reduced power consumption. Cerro Verde represents the first installation of HPGRs in both the copper industry and large scale hard rock mining.

Jan 1, 2012