Search Documents

By Juliana Parreira

The past decade shows record increases in global demand for minerals and metals with an accompanying significant decline in skilled personnel. Mining companies today are examining new technologies to maximize production, reduce costs, and create safer work conditions to deal with this shortfall. Automation of an open-pit mine haulage system is receiving attention as a beneficial option since it provides more consistent and efficient operation of mining equipment, it removes workers from potential danger, it reduces fuel consumption significantly reducing greenhouse gas (GHG) emissions, and it can help optimize vehicle repairs and equipment replacement because of more-predictable and better-controlled maintenance. This paper describes a simulation model under development using the EXTENDSIM software package to examine scale-up issues and constraints of autonomous vehicles in comparison to a manual system. The software can predict and manage Key Performance Indicators (KPIs), such as productivity, safety, cost, equipment failures, fuel consumption, and tire wear under different road and load conditions. By breaking-down the various systems of an autonomous haulage truck and simulating the overall haulage system using a Monte Carlo approach, the model becomes a flexible and powerful tool to use within a mining organization. Direct comparison to a manuallyrun system can be done to show the cost and operational benefits of automation. Project managers can use this tool to guide decision-making about possible application of autonomous haulage trucks at a specific mine site.

May 1, 2010

By Joe Price

Canada?s energy future will increasingly depend on a supply of light, sweet crude oil derived from the Athabasca oil sands deposit of North-eastern Alberta. Billions of dollars are being spent on the construction of new and expanded mine and bitumen extraction plants, in situ recovery facilities, pipelines, upgrading installations and all the infrastructure needed to support these projects. The success of the existing operators has also inspired new players, anxious for ?a piece of the action? to come forward with exciting project proposals of their own. None of this investment and spin-off economic activity would be taking place today if events had unfolded differently in this part of the world some one hundred million years ago. The accumulation of sand in rivers, estuaries and in the near-shore marine environment created the great reservoirs that host the enormous oil deposits these projects are designed to exploit. Mine operators of all stripes will likely agree that there are few good ?geological surprises?. With specific reference to oil sand deposits, the geological history determines the distribution of sand, silt and clay bodies, which in turn controls the ore grade. Important design factors including everything from stable pit slope angles to tailings properties reflects events that took place millions of years before. An understanding of the sequence of events that resulted in deposition and preservation of the sediment and oil are important to sound design for both mining and in situ facilities. A geological history of the region is described. Site-specific examples from Syncrude?s operating mines are used to illustrate some of the geological factors that can present design challenges.

May 1, 2003

By F. Goodarzi

"The nature and distribution of the inorganic components and the concentration of certain environmentally sensitive elements, such as, As, Sb, B, Hr, Cd, CI, F, Mo, Pb, S, and Se, or elements detrimental to the utilization by industry such as B, Na, P and S are very important in determining coal quality. The concentration of elements in coal is controlled by the following factors: (1) frequency of occurrence of partings; (2) nature and habit of occurrence of minerals in coal; (3) environment of coal deposition; (4)rank; (5) geological setting; and (6) weathering.Selective mining of coal can reduce the input of undesirable elements such as As and S by eliminating the part of the seam which is enriched in these elements. IntroductionCoal is a sedimentary rock of plant origin and consists of two components: an inorganic component (minerals) which is formed by influx of clastic sediments into the coal-forming environment and also by activities of groundwater, and an organic component (macerals) which is formed from plant debris deposited in the original coal-forming environment. However, coal is a generic term with a broad range of utilization characteristics. A coal that is attractive for use in one market - such as generation of electricity (combustion) - may not necessarily be acceptable for use in another, such as for production of coke (Davis, 1978).The elements in coal are associated with both macerals and minerals. The elements associated with coal macerals, such as C, H and N are termed elements with organic affInities. The concentration of elements with organic affmities (including B, Br, CI, F, I, S, and Mg) often decrease with increasing ash content of coal (Nicholls, 1968; and Finkehnan,1982). FIgure 1 shows such a trend for chlorine. Some of these elements may also be incorporated in coal maceral as very fine mineral grains (Finkelman, 1982). The elements with organic affmities are often volatilized during combustion and carbonization of coal and emitted in the vapour phase. Emission of some of these elements (C, 0, Br, N and S) is of major environmental concern (Lim, 1979)."

Jan 1, 1994

By Peter A. Witt

Highland Valley Copper is a conventional truck-shovel mining and flotation concentrator operation located some 75 kilometres southwest of Kamloops, B.C. (Figure 1). The ore is within a porphyry deposit and is mined at a rate of 135,000 metric tonnes per day from two separate open pits. The nearby mill produces concentrates containing 375 million pounds of copper and 5 million pounds of molybdenum metal yearly. Head grades are roughly 0.40% Cu at a 0.23% Cu equivalent cut-off. The strip ratio currently sits at 0.55:1 with waste quantities made up of separate rock and unconsolidated overburden units. From the mill, concentrates are trucked to nearby Ashcroft and then hauled by rail to ocean port facilities in Vancouver. The mine employs 950 persons and is planned to operate until 2009. The operation is a partnership between three owners: TeckCominco (61.4%), BHP Billiton (33.6%), and Highmont Mining (5%). Management is shared by the two principal owners and directed by an appointed committee.

May 1, 2002

By Ning Yu

There are about 1.341 trillion tons (t) of proven coal reserves in China, of which 279.58 billion t are available for mine well construction basis. Thick coal seams are 44% of the reserves. The production of thick coal seams exploitation is over 45% of the total coal production. Full-seam mining and fully-mechanized mining for large mining height is the technology development direction of thick and extra thick seam mining. It is also the important way to achieve efficient and intensive mining with the characteristics of high production, high mechanization, high efficiency and low energy consumption, etc. Complete set of technology and equipment of fully-mechanized top caving for large mining height of full-seam (7m) mining and extra thick seam ( 14-20m) has been gradually mature and for demonstration application by the joint research of government, enterprises, universities, scientific research organizations and users. It has solved some technical problems of coal face for large mining height (over 7m) such as the coal wall spalling control, stability of support, wall rock coupling, cooperation work of mining and caving, full roadway support for super large section, end support, equipment matching of coal shearers, hydraulic support and scraper conveyor. It has developed key equipments including powerful hydraulic support of fully-mechanized mining and fully-mechanized top caving for large mining height, electrically-driven coal shearer with high speed and reliability, scraper and belt conveyer with big capacity, soft-start and high reliability, automatic control system of coal face with the core of electric-hydraulic control, bolting drill boom large section coal roadway shearer, heavy auxiliary transport equipment. The operation rates of fully-mechanized top caving equipment for full-seam and large mining height are 94% and 92.1%, and recovery ratios are 93.6% and 88.9% respectively. The annual raw coal production of single work face is over 10 Mt. The automation and intelligentization level have been clearly improved. The exploitation of thick and extra thick coal seam that is safe and efficient has been achieved in China.

Aug 1, 2013

By Brian C. Maynard

"Blast design is becoming more and more important as industrial limitations change in regard to economical and physical restraints. Certainly there are ways to alter the nature of the blast by using different explosives, various hole sizes and modifying the timing and charging details. However, it is not possible to alter the fabric of the rock mass. Therefore, it is necessary to learn more about the rock mass and its role in the blast design, and the resulting fragmentation. The major determinant in the degree of fragmentation, or lack of it, is proposed to be the inherent fragmentation of the in situ rock mass. A practical method of quantifying the discontinuities existing in the rock mass is presented and discussed. Likewise, the effects of inherent fragmentation on the resulting muckpile are reviewed. Finally, a fragmentation model combining the calculated inherent fragmentation and the Kuzram model is shown using a sample blast.IntroductionIn blasting, discontinuity characteristics (Fig. 1) control the method by which the rock mass will behave. Research carried out by Piteau (1970) showed a number of characteristics important in engineering design and, as proposed, in blasting processess. These included:• the nature of their occurrence (i.e. sets or isolated);• orientation and position in space;• continuity; and• intensity"

Jan 1, 1990

By Eric Pirard

"A mineralogical and trace element analysis was performed on the Küre historical slags in order to evaluate the possible recovery of copper and cobalt. Reflected light microscopy, electron microprobe and image analysis were combined to determine the Cu and Co distribution in the slag.The results indicate that 81% of the total cobalt is chemically combined in the fayalite whereas only 3.4% is in the mechanically entrapped sulphides. The remainder being in hercynite and wiistite. On the other hand, 95% of the total copper is in the sulphide phase.This kind of applied mineralogical investigation gives invaluable information when it is performed preliminary to metallurgical experiments.IntroductionThe recycling of metallurgical slags is a growing business. The operation is directed toward recovering base metals (Cu, Pb, Zn), and by-products (Floyd and Mackey, 1981).Two reasons are invoked to explain metallic losses in slags: (1) mechanical entrapment of matte globules in the silicate melt; and (2) chemically combined metals in the slag-forming phases. Obviously, a chemical analysis of the slag cannot distinguish between those two modes. Grinding and flotation of the liberated sulphides have often been used to evaluate the importance of mechanical entrapment (Mechev, 1970; Imris , 1982).Recent studies in applied mineralogy of pyrometallurgical products (Bérubé et al., 1987; Pignolet et al., 1986) have demonstrated the benefits of quantitative mineralogical analyses of slags. Optical microscopy together with electron microprobe and image analysis offers a powerful and easy way of quantifying the relative importance of mechanical and chemical losses."

Jan 1, 1991

By R. Pakalnis, H. Miller, Madill. T.

"This paper describes a methodical approach to the estimation of the orientation and the magnitude of in-situ stresses. The study was performed at the Ruttan Mine, Sherritt Gordon Mines Ltd. , a 6,000 T.P.D. underground operation, located in northern Manitoba, Canada. It involves an initial estimate to be made based upon: structural interpretation • virgin stress measurements conducted in other areas (world wide, regional)The verification of the prevailing stress regime was made by conducting CSIRO hollow inclusion(1) overcoring measurements. The current cost for a virgin stress determination is about $7000 per measurement(2) and the difficulty encountered in attaining a good reading is high. This paper will describe the analytical procedures employed at Ruttan in evaluating the in-situ stress magnitude and orientation based on three overcore tests. It is proposed to perform an additional six measurements in order to verify the following results:Vertical stress = av (MPa) = 0.027 by depth (m)Major principal stress = o! """" 2.5 xav (340°/-20°)*Intermediate principal stress = a2 - 1.2xav (070°/0°)Minor principal stress = a3 """" o.8xov (160°/-70°)IntroductionThe Ruttan Mine of Sherritt Gordon Mines Ltd., a 6,000 T.P.D. underground operation, is located in northern Manitoba, Canada (Fig. I). The Ruttan copper-zinc orebody is a multi-lensed, steeply dipping (70 degrees) en-echelon deposit. Individual lenses have a maximum strike length of 350 m with widths varying from 7 m to 61 m. The mining method is o pen stoping with delayed backfilling and extends from surface to 860 m below surface."

Jan 1, 1985

By T. M. Siew

"This paper begins with a brief discussion of the geology of the Newfoundland Zinc Mine area. The results of groundwater studies and pumping tests are then presented. It was decided that groundwater in the mine could best be controlled by conventional sump pumping and grouting. The system is fully described, as well as plans for improvements on the method. LocationThe Newfoundland Zinc Mine is located in the Great Northern Peninsula of Newfoundland, six miles northeast of Daniel's Harbour. The mine is situated at an elevation of approximately 350 feet above sea level, 5 miles farther inland , west of the long range of mountains which rise abruptly with elevations of over 2,000 feet above sea level.GeologyThe ore deposits occur in lower Ordovician carbonate rocks that form part of the stable St. Lawrence platform, which is mainly composed of (1) the lower Cambrian Labrador group, (2) the upper Cambrian to lower Ordovician St. George group, (3) the disconformity overlying Middle Ordovician limestones and shales of the Table Head formation and, (4) two overlying klippen composed of Cambrian and lower Ordovician rocks.The ore deposit is a Mississippi Valley type of the Tennessee variety, having proven are reserves of 5.3 million tons averaging 9.70/0 zinc from eleven ore zones which exist in an area of 5.5 square miles.Among these ore zones, the L zone is the major underground mining area, and is by far the largest of the known deposits. It has proven are reserves of 3.4 million tons with 11.5% zinc; this underground development has been inprogress since 1974.Stratigraphically, the orebody, which occurs about 300 feet below the disconformities between the Table Head and St. George formations, is situated in the upper St. George formationof lower Ordovician age.The upper St. George formation of the L zone is divided into three main units (Fig . I) : the underlying lower limestone the middle grey dolomite pseudo breccia unit and the overlying siliceous dolomite unit. In this area of the mine, the beds of the St. George formation dip gently west to northwest to 10 to 15 degrees. The orebody, which is generally strata controlled with a southwesterly plunge and which has the form of thin, narrow, but elongate, en-echelon ore bed s, is contained in grey dolomite pseudo breccia. Its dimensions vary from 50 to 900 feet in width and 8 to 120 feet in thickness, and the over-alllength exceed s 6,000 feet.The surficial deposit of the area is a till comprising a heterogeneous mixture of sand, gravel, cobbles and boulders, with an average depth of 20 feet."

Jan 1, 1980

By D. Laguitton, D. Cimon

"BILMAT is one of the most powerful algorithms in existence for material balance computation in mineral processing flowsheets. It is based on a hierarchical decomposition coupled with the Lagrange multipliers method widely reported in the literature. Flowrates can be calculated optionally for pulp, solid or water. Assays are adjusted for a variety of subnetworks, such as assays of the solid as well as assays of fractions of the solid called level 4 data (l: pulp, 2:solid and water, 3:assays of solid, 4:assays of classes of solid).BILMAT4 is a new implementation of BIU1AT that operates in a new microcomputer environment and makes the method more accessible than ever. Its main features are a full-screen colour editor allowing graphic flowsheet drawing and data entry with automatic error checking. Mass balance equations are automatically generated by analysis of the graphics and corresponding data, thus relieving users from the error-prone definition of networks. Sensitivity analysis is performed to assess confidence intervals of computed flowrates and adjusted assays.BILMAT4 incorporates an option for gold leaching circuits where the element to be balanced appears in both the solid and liquid phases with negligible effect on the mass flows of solids. Recoveries are computed in all streams. This program is currently released by CANMET as part of the CAMP collection for Computer Aided Mineral Processing. A complete sample run of the program is discussed."

Jan 1, 1989

By Candido Bariáin

A new vapochromic material of formula [Au2Ag2(C6F5)4(bipy)2]n (bipy = 2,2´ bipyridine) has been developed and used for the detection of some volatile organic compounds as acetone either in vapour or in water solution. The material is presented in the form of powders which colour changes with acetone vapours turning from bright yellow in the absence of vapour to white in the presence of vapour. By using the sol-gel technique, the powder ? dispersed in tetraethyl orthosilicate- was easily deposited on optical fibres. In order to study experimentally the behaviour of this material for construction practical optical fibre sensors, a sol-gel material doped with the vapochromic material is deposited onto an extreme of a monomode fibre connected to a coupler. The behaviour of the material was studied for different wavelengths and concentrations of acetone vapours and acetone/water solutions. Changes up to 4dB in the reflected optical power were detected. Optical fibre sensors have many advantages over conventional ones, such as electromagnetic interference immunity, passivity behaviour, possibility of using multiplexation techniques, low weigh and little size, etc. Actually, there is an increasing interest in developing optical fibre sensor for vapour detection in the chemical industry and in fact many sensor had been developed [1]. Some are based on the deposition of a sol-gel-based material either over the core of an optical fibre [1] or onto the thinner zone of a biconically tapered optical fibre [2]. Others are based on Fabry-Perot interferometers [3]. Also there are sensors based on the reflection of the light on films, on the fluorescence of dye-doped polymer cladding in fibre, on colorimetric reagents in the core of a silica fibre or on surface plasmon [4]. The possible materials for the construction of such sensor should be colorimetric reagents able to change the colour or refractive index in the presence of same organic vapours. There are not many metallic complexes with these properties, although same interesting examples have been reported in the chemistry of palladium and platinum as [Pt(p-R-C6H4NC)4][Pd(CN)4] described by Nagel [5] and Mann [6], which reported the construction of some LEDs. We recently reported the preparation of a novel vapochromic material (Fig 1) [7] which can be used for the construction of optical fibre tapered environmental sensors [8,9] of vapour organic compounds (VOC´s). Also we reported other nickel and palladium derivatives which present this type of behaviour [10]

Oct 1, 2003

By Bo R. Arvidson

"New permanent magnetic alloys have recently opened up possibilities for development of unique mineral separators. These are now making several new applications feasible. In many cases where conventional electromagnetic-induced roll separators have traditionally been used, the new permanent magnetic roll separators may reduce both over-all capital costs and operation costs.The development of the next generation of extremely powerful permanent magnets, i.e. neodymium-iron alloys, is progressing rapidly and will affect the roll separator as well as another type of magnetic separator. Permanent Magnet Roll SeparatorDesign and FeaturesDiscs of permanent magnets interleaved with soft iron discs constitute the basic magnetic roll design (Fig. I). By enveloping the magnetic roll with a thin abrasive resistant belt (Fig. 2), even highly magnetic particles are removed.The first prototype roll utilizing the new magnets was shown to have approximately equal strength as induced magnetic roll (IMR) separators. Since the initial test roll, the new separator, called the PERMROLL® , has been made twice as strong with regard to magnetic force, that is, the magnetic flux density is determined to exceed 1.7 tesla (17 kilogauss), while the magnetic field gradient is more than twice the gradient than can be practically achieved with IMR."

Jan 1, 1985

By James J. Roettger, Robert J. Mitchell

"The results of a series of model stope pours designed to investigate working pressures on bulkheads during hydraulic pouring of classified tailings backfill are reported. Total bulkhead pressures and fill water pressures were monitored under the condition of a fully saturated backfill. Similitude of the model testing is discussed and equations are developed to estimate bulkhead pressures under prototype conditions. The model results show that good base drainage, combined with a bulkhead setback, can reduce the expected bulkhead pressures to values such that timber or concrete block structures should be capable of supporting a saturated backfill. Introduction Bulkheads are used in underground running operations to block drift openings in order that hydraulically placed sand backfill can be contained in stope pours. Whenever possible, the sand fill is designed to have sufficient percolation rate so that excess hydraulic transport water will gravity drain out through the bulk headed drifts. This avoids costly decanting systems. Early bulkhead design assumed that the bulkhead pressure could be as high as 0h = Hy where H is the fill height and ""y is the saturated unit weight of the fill (Thomas et al., 1979)(1). A typical design pressure for a 50 m fill height would be 1250 kPa giving a design force of 12,500 kN on a bulkhead located in a drift of 10m2 in area . Typical bulkheads were 1 m thick heavily reinforced concrete structures formed and poured into a notched drift. Not only were these expensive structures but the associated problems of inside drainage systems and curing time delays increased production costs. As experience with bulkheads for large bulk pours increased and fill pressure measurements became available [see, for examples, Libby et al., 1975(2), Askey et al., 1978(3)] , 'free drainage' timber and concrete block bulkheads were designed. Substantial savings have been realized using these types of bulkheads but greater engineering design and monitoring of backfill pours is necessary to ensure that backfill pressures do not exceed the bulkhead design pressures.The effective and total stress components of fill pressure, the engineering concepts associated with the 'free drainage' design and some detailed design considerations have been discussed by Smith and Mitchell (1982)(4) . It is important to the safe use of these designs, however, that the basic engineering concepts be demonstrated and communicated to those responsible for the day-to-day backfill operations. This paper describes and explains observations from a series of model studies designed to measure bulkhead pressures in a saturated fill."

Jan 1, 1984

By Robert B. Parsons

"It is generally felt that flow-through shares face a bleak future under the set of tax rules proposed in the federal government's tax reform white paper. Industry and government circles are beginning to give thought to alternatives to flow through as a mechanism for facilitating equity financing in the exploration industry. Despite suggestions that grants and tax credits may someday be on the table, industry is sticking to its position that there is no substitute for flow-through. Alternatives toFlow-throughProposals in the federal government's tax reform white paper have cast significant doubt on the ability of the mining industry to raise risk capital after 1989by way of flow-through shares. There is serious concern that introduction of the ""cumulative net investment loss"" (CNIL) rules, the phase-out of the mining explorati0! 1 depletion allowance (MEDA), and the Increased capital gains inclusion (750/0 versus 50%, at present) will make the economics of flow-through so unattractive after 1989 that these shares will hold little appeal to most investors. The question might be raised, then, as to what alternatives exist by way of tax or other government assistance that could help the exploration sector.The purpose of this paper is to survey the types of government incentives that could be of some value to explorationists and to the mining industry in general. For the past several years, flow-through has been in the spotlight insofar as incentives to the exploration industry are concerned. Other potentially useful and attractive incentives have been partially hidden in the shadow of flow-through. These incentives, in certain circumstances, can be of considerable benefit, and should not be ignored."

Jan 1, 1988

By T. Crivits, I. Bellemans, V. Cnockaert, K. Verbeken

It is well known that slag foaming can significantly complicate copper smelting processes. This is especially true for unpredictable events that generate large amounts of slag foam during a small period of time. These events are here referred to as eruptions and are typical for certain types of liquid bath furnaces such as modern top submerged lance (TSL) furnaces. A few authors already made the link between over- oxidation of the slag phase and slag foaming. In this work, the mechanism is studied in more detail and explained using the smelter chemistry and the behaviour of dynamic foam formation. Finally, the most influential parameters on the foaming behaviour of the process are presented. INTRODUCTION Copper remains one of the most important metals used in our modern society. In 2017, the annual amount of copper produced worldwide was about 23.5 million metric tons. This makes copper the third most produced metal in the world after steel and aluminium. The majority of this copper was produced by copper smelting, about 19 million metric tons, both from primary concentrate and secondary feed material as reported in ICSG’s World Copper Factbook 2018. In the past, copper smelting was mainly performed using Flash smelting, a technology developed before 1949 (Kojo, Jokilaakso & Hanniala, 2000). Nowadays, this type of smelter is being complemented by other smelter types such as ISASMELT and Ausmelt technologies. These are two types op smelter furnaces, based on the concept of a top submerged lance (TSL) furnace. These two technologies were both commercialized around 1990 (Arthur & Hunt, 2005). It is estimated by Wang et al. (2016) that at this time, both flash and TSL smelters contribute equally to the total amount of annually smelted copper. Flash smelting stays the most important technology for extracting copper from primary sources. TSL furnaces, on the other hand, are more suited than Flash smelters for the recovery of copper from secondary materials. This is because of the different ways that the feed material is inserted in both furnaces. In Flash smelters, the ore and fluxes needs to be fine and completely dry in order to be able to blow the mixture inside the burner area of the furnace. The feed material for TSL smelters show less constrains concerning humidity and particle size. The material is dropped from the top inside the molten bath. As a result, a more complex and flexible feed stream can be processed using TSL smelting (Wood, Hoang & Hughes, 2017). This feature will become more important in the future as primary copper sources gets more scarce and the need for a fully sustainable material cycle increases.

Jan 1, 2019

By F. R. Ploeger, J. H. Crocket

"IntroductionRocks in the Kirkland Lake district form part of the Timiskaming Group, a south-facing homoclinal sequence of wackes, conglomerate, trachytic flows and pyroclastic rocks and syenitic intrusive rocks. Hewitt (1963) indicates that the thickest section, about 5 km, of the Timiskaming Group rocks is attained in Lebel Township. Several writers (Thomson, 1948; Hewitt, 1963; Hyde, 1978; Jensen, 1978; and Downes, 1979) have observed that the Timiskaming Group unconformably overlies the Keewatin volcanics, particularly along the northern contact. Recent work by Downes (1979) in McGarry and McVittie townships to the east of Kirkland Lake has shown that much of what had formerly been classified as Timiskaming actually belongs to an older group of rocks, the Larder Lake Group (Jensen 1978).General GeologyA series of fluviatile, braided-stream sedimentary rocks (Hyde, 1978) form the oldest of the three major rock suites at Kirkland Lake. Conglomerates constitute a large proportion of these sedimentary rocks and typically contain a large percentage of a variety of locally derived alkalic rock clasts as well as the distinctive red jasper iron-formation pebbles (Fig. 1a). The associated wacke units can be massive to finely bedded and are interbedded with the conglomerate. They also contain a large alkalic tuffaceous component.Interbedded with these sedimentary rocks are alkalic extrusive rocks, including tuffs, agglomerates, breccias and flows, which represent episodes of fissure and explosive crater eruption (Cooke and Moorhouse, 1969). The tuffs, although dominantly alkalic in composition, are commonly reworked and contain sedimentary features such as graded bedding, scouring and crossbedding (Fig. 1 b). The trachytic flows are massive to porphyritic and outcrop mainly east of Kirkland Lake in the adjoining townships. Altered leucitic porphyritic flows, locally referred to as red and green spotted trachytes, commonly occur."

Jan 1, 1982

By P. Woo, N. Brodusch, R. Gauvin, H. Demers

The scanning electron microscope (SEM) was primary developed for imaging applications. With the introduction of the Si(Li) energy dispersive spectrometer (EDS), simultaneous imaging and x-ray microanalysis became possible. However, long working distance and high current were needed because the position and small solid angle of the EDS detector. The high spatial resolution is generally obtained at short working distance with a SEM. Unfortunately x-ray microanalysis is never performed in the best imaging conditions. The annular silicon drift detector system is inserted below the objective lens which gives a higher solid angle (up to 1.3 sr). In consequence, a lower working distance and probe current can be used. An improved spatial resolution becomes possible during x-ray microanalysis. With this x-ray detector installed on a cold-field emission scanning electron microscope, quantitative x-ray microanalysis with high spatial resolution at low beam energy and low current becomes possible with the possibility of using the various different type of imaging at the same time. Also, since the count rate can be as high as 1,500 kcps, which lowers significantly the detection limit of elements as well as the minimum feature sizes of different phases that can be distinguished.

Jan 1, 2014

By K. Enns, J. J. Byerley

"While thiocyanate (SCN-) is used in a number of industrial processes (production of polyacrylonitrile filaments, synthesis of agricultural chemicals and certain metallurgical solvent extraction and flotation circuits) it is recognized more as an undesirable by-product associated with ' the metallurgical industry. Thiocyanate is present at low concentrations in some waste streams from the iron and steel industry. Of particular significance is the formation of thiocyanate during cyanidation of gold and silver ores, concentrates, tailing s and residues. The thiocyanate levels present in the resulting effluents may range from a few mg/I to several thousand mg/I.At present, thiocyanate does not appear to be as hazardous in the environment as cyanide (CN-) at the same concentration although its interaction with other species and resulting decomposition of products may be unacceptable. Of course the presence of thiocyanate in the leaching circuit and ultimately in the effluent streams may add considerably to the oxidative requirments of any non-selective treatment process for cyanidation wastes.With respect to the thiocyanate as it relates to the cyanidation process, two aspects are evident. Thiocyanate forms and persists in the cyanidation circuit resulting in a ""fouling"" condition with subsequent loss of leaching activity. In order to reduce or control this problem, it is common practice for some mills to discharge daily as much as 20% of the barren leach liquor. Besides contributing to fouling of the leach liquor the formation of thiocyanate represents an irreversible loss of reagent cyanide. It is noteworthy that in some present or proposed mill practice reagent cyanide loss through thiocyanate formation may reach 50%(1). The purpose of this paper is to discus s the application of controlled electrooxidation of thiocyanate with the view of suggesting a process for regenerating cyanide from waste thiocyanate(2). The paper describes the important theoretical aspects and presents experimental data obtained for thiocyanate electrooxidation using both small and large scale electrochemical reactors. Some economic conclusions are presented."

Jan 1, 1984

By Paul E. Mather, Matthew J. M. Krane

Anode or fire refining is the final pyrometallurgical step in the production of copper anode. Part of this process purifies liquid copper by reducing its dissolved oxygen with a natural gas-steam mixture. Until now there have been no transient models of this process coupling the injected gas jet mass transport with its chemical reactions. A transient, 1D flow, chemical reaction model was made to estimate the time-dependent behavior of anode copper composition, soot formation, and the transient gas jet composition along its height. Model estimates were made for reduction rate, soot emission rate, and exergy loss and destruction distributions for two melt temperatures and a range of steam addition rates. It was found that increases to melt temperature and steam addition rate increased reduction rate and decreased soot emission, while having little effect on exergetic performance. Estimates for reduction histories were compared to industrial data. INTRODUCTION Anode/fire refining is the final pyrometallurgical step in the production of copper anodes; it is essential for removing dissolved gases which cause porosity in cast anodes. Despite its significance, the open literature appears devoid of any transient models of the entire process; furthermore, there are very little published process data with which to validate any models made. This dual dearth of modelling work and process data inhibits studies of the tradeoffs between process and performance changes, desirable for decreasing reduction time and soot formation as well as quantifying changes in the exergy losses and destructions of the process. This work introduces a reduced-order, transient model of reduction during fire refining, examines performance trends with operating conditions, and compares model estimates with industrial data. Overview of anode refining The purpose of anode refining is to produce liquid copper which can be cast with minimal gas porosity, which disrupts the downstream electrorefining process. Dissolved sulfur is removed first, then oxygen, by reactions with different injected gases. The removal of oxygen (the reduction step) is the subject of this proceeding and is effected by the bubbling of natural gas, typically mixed with steam, through the melt from tuyeres. A typical refining run reduces dissolved oxygen from 3000 ppm to 300 ppm in 2–3 hours (Schlesinger, King, Sole, & Davenport, 2011). The refined copper is then cast as anodes. Figure 1 shows a schematic of the furnace vessel.

Jan 1, 2019

By G. Vibert Douglas

Introduction A preliminary paper dealing with the subject of ore-shoots was presented to this Society at its Annual Meeting last year (1). The present paper records the attempts which have been made during the interval to further this study. In reporting this work, I wish to state that I do not consider the investigation complete; many more experiments will have to be carried out, and more field data will have to be recorded, before the geologist can say with confidence an ore-shoot should start at this point and pitch in that direction. The aim of these experiments is to find some criteria which will serve the mining engineer and mining geologist concerned with ore-shoots in hydrothermal veins.

Jan 1, 1935