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By D. Lessard, S. Nantel

"Surface crown pillars are important Canadian,mining structures. Mines operating in the Canadian Shield usually have several, forming a first line of protection from surface elements.Detailed technical information from twenty-four Canadian hard rock mines show that the deposits dip steeply and are generally either single or multiple veins. Considerable overburden usually cap the deposits. The rock mass is often altered and intersected by important discontinuities.The designs for these types of pillars lack basic data and are based on experience rather than a scientific approach. Regardless of the competence of the rock mass, the surface crown-pillar thickness to width ratios (an unscientific design tool used by the industry) are usually less than five. Rock bolting is, in almost every case, used as a support measure. However, there are many openings neither backfilled nor monitored.The characteristics of openings with surface crown pillars are also examined."

Jan 1, 1988

By Yongteng Dong, John P. Quinn, Bradford Wesstrom, Guikuan Yue

With increasingly low-grade copper ores being mined, it is difficult to handle growing concentrations of As, Sb, Bi and/or Fe in the whole flowsheet, especially during copper electrorefining. To better elucidate the effects of those impurities on the quality of cathode deposit and/or current efficiency, a detailed speciation study of the electrolyte under industrial conditions is required to quantitatively describe their distribution in the solution, thereby facilitating their effective control and removal. In the present study, a thermodynamic model of complicated iron-arsenic-copper-sulfuric acid electrolyte under industrial conditions was developed. The main species of those elements involved in the electrolyte were first identified, and their thermodynamic data were collected and critically assessed. Those data were then used to estimate the activity coefficients of species, and to calculate the equilibrium constants from 25°C to 70°C. The developed model provides a mathematical tool that is capable of quantifying the concentrations of free ions and complexes in terms of temperature and solution composition. Finally, oxidation-reduction potential measurements were employed to validate the model. INTRODUCTION In copper electrorefining, impurities like arsenic, antimony, bismuth and/or iron can partially dissolve in the electrolyte and accumulate gradually, and eventually cause problems such as bad cathode deposit (co-deposition with copper or mechanical inclusion from the floating slime), lower current efficiency, etc., which eventually increases the operating costs. The presence of impurities may substantially reduce properties of copper products such as conductivity, corrosion resistance, mechanical properties, and leads to more energy consumption (Schlesinger et al., 2011; Jafari et al., 2017). To remove these impurities, various methods have already been proposed and applied in industrial copper production, such as solvent extraction, ion exchange, chemical precipitation, absorption by activated carbon, etc. (Cunningham et al., 1997; Navarro et al., 1999; Toyabe et al., 1987). In addition, adding reducing agents such as sulfur dioxide and trivalent arsenic could also precipitate arsenic, antimony and bismuth from copper electrolyte, by changing the distribution of impurities with various valence (Braun et al., 1976; Xiao et al., 2007). The disadvantages of those methods include high energy consumption, serious contamination, lower selectivity and efficiency, and so on.

Jan 1, 2019

By Martin Wacker

Cameco Corporation, on behalf of a joint venture, is preparing surface and underground facilities at their northern Saskatchewan property in preparation for the future operation of a high-grade uranium mine. The Cigar Lake orebody is situated about 430 metres below surface at the unconformity between metamorphic basement rocks and flat lying sandstone. Major technical factors influencing the mining method selection include ground stability, control of ground water, radiation exposure and ore handling and storage. A decade-long test mine program resulted in the selection and validation of ?jet boring? a non-entry mining method. Cigar Lake?s jet boring mining method involves several major steps; artificial ground freezing of the orebody and surrounding rock, TBM (tunnel boring) type development of access crosscuts below the orebody, installation of cased pilot holes upwards through the ore, and ore extraction using a rotating high pressure water jet within the pilot holes. The resulting cavities are surveyed and backfilled with concrete. The ore slurry will be processed underground and pumped to surface. This paper discusses the jet boring mining method in general terms and includes highlights of the Cigar Lake test mine program completed in 2000.

Apr 1, 2005

By A. L. Mular

"IntroductionSince the mid -1960s, automatic control of grinding circuits has become the rule, to avoid losses attributable to frequent circuit upsets associated with uncontrolled disturbances such as ore hardness variations. Higher capital costs of grinding equipment and corresponding operating costs-especially with respect to energy consumption-are major factors that continue to stimulate interest in grinding control.Grinding circuit control strategies depend upon the control objectives defined by the processing plant and are subject to constraints such as: maintain final per cent solids within some range, do not transport steel ball s out of the discharge trunnion, or do not overflow or empty the pump box and so on. Constraints depend on the nature of equipment employed within the grinding circuit and may actually determine the characteristics of the control scheme. Typical control objectives are:1. Maintain final particle size at set point by ,a. manipulation of fresh feed rate with circulating load maintained by manipulation of pump box water addition rate, orb. manipulation of pump box water addition rate with circulating load maintained by manipulation of fresh feed rate, where the methodology utilized to accomplish either (a) or (b) is dependent upon equipment/circuit constraints such as the availability of a variable speed pump.2. Maintain circuit throughput at a maximum by,a. manipulation of fresh feed rate subject to constraints on final particle size and variables such as power draw, circulating load and mill overload.3. Maintain mill load at set point by a. manipulation of fresh feed rate subject to constraints such as on power draw.4. Maintain mill power draw at set point bya . manipulation of fresh feed rate subject to mill load constraints. Often, a grinding control objective is dictated by the recovery vs fineness-of-grind characteristic that exists for downstream separation circuits. When recovery is relatively insensitive to size, maximum throughput in the grinding circuit is advantageous.The purpose of this paper is to review control strategies for primary ball mill grinding circuits, rod mill/ball mill grinding circuits and semi-autogenous grinding mill circuits. Primary sensors employed are highlighted and modern trends are documented briefly."

Jan 1, 1989

By Steve Lalancette

Centre Jardin Lac Pelletier (CJLP) has been a leading actor in the revitalisation of closed mining sites in northern Québec for over 20 years. Over that period, CJLP developed a cost-efficient technique that transforms sterile mining residue into a substrate able to support a resilient ecosystem. Using a unique mix of organic matter, fertilisers and selected plant species, this technique rapidly builds a microorganic fauna and a layer of humus that will sustain the creation of vegetation coverage. The coverage is composed of over 13 different plant species, each having a unique role in the development of a resilient ecosystem, from soil stabilisation to nitrogen fixing. Considerably less expensive than traditional methods using civil engineering techniques, it does not require the use of heavy machinery or the spread of topsoil. This technique has been successfully used to restore over 20 sites in Québec such as Joutel, Yvan Vézina and Louvicourt. It is a proven technique that has passed the test of actual implementation. The presentation will review the biological, production and economic aspects of the technique through the revitalisation of the Joutel site.

May 1, 2011

By P. W. Udo Graefe

"An interactive computer model of a dragline, windrow and spoil pile has been developed for modelling oil sands mining operations. The model is to be used in conj unction with models of other oil sands mining equipment, such as bucket-wheel excavators and reclaimers, conveyors, hoppers, bins, trucks and shovels, to study mining operations on a minute-by-minute basis. From the orebody description and mining selectivity, layers of ore and reject are determined and mined by the dragline. Reject is dumped on the pit floor; ore is either dumped on a windrow for later removal by a bucket-wheel reclaimer or directly dumped into a hopper feeding a conveyor. The model allows for the presence of pads as a dragline base, key cuts and a number of interruptions to the mining operation such as shift changes, boom checks, engineering services, repairs, delays, preventative maintenance, etc. A CRT display keeps the model operator informed about equipment status and performance. The model operator can direct the course of the simulation by issuing commands to the model at any time during the simulation.IntroductionThis paper describes an interactive computer model of a dragline, windrow and spoil pile. The model was designed by the author based on information and specifications provided by Canstar Oil Sands Ltd. The model design was implemented and tested on Petro-Canda's IBM computer system by DMR and Associates Ltd. of Calgary, Alberta.The model was designed to form three components of an oil sands mining operations model, described in reference I. Figure 1 shows the interaction of those components with the remainder of the oil sands mining model.An ""Ore/Waste Body"" data base provides information to the dragline model about the location and composition of or e and waste in the mine. The dragline model is used to simulate mining this ore/waste body, to build up spoil piles for center reject (waste) and to dump ore onto windrows or hoppers (situated over conveyors) to deliver the ore to the extraction plant. The windrow model component provides a data base which will be used by a model of a bucket-wheel reclaimer which simulates the loading of ore from the windrow on to a conveyor via a bridge."

Jan 1, 1982

By Robert B. Parsons

"The new Ontario Liberal government introduced its first budget in October. The changes to The Mining Tax Act proposed in the budget are mean t 10 simplify the current system without any loss of revenue to the government. It goes without saying that some operators will benefit from the changes while others will pay more taxes after 1985.With regard to ongoing matters at the federal level, the proposed carve-out legislation and the issue of northern allowances are being discussed with government officials, and a small victory has recently been scored with regard 10 the laxation of certain share transactions of prospectors and grubstakers. A report on these issues is provided herein.Ontario BudgetOn October 24, 1985, Ontario Finance Minister Robert F. Nixon tabled a budget proposing several significant changes to both the Ontario Mining Tax Act and the province’s income tax legislation.Mining Tax ActA flat rate of tax and reduced processing allowances highlight proposed changes to The Mining Tax Act. The proposed changes, with a comparison to the existing system, are set out in Table I.The most significant change is the replacement of the graduated tax rate schedule with a flat 20010 tax rate. This is a welcome change for most mine operators who viewed the high rate of 30% on profit over $20 million as counter-productive.However, the flat rate of ta x may not be welcome to all operators. Generally speaking, operators with less than $ 10 million annual profit are better off under the graduated rate system, while operators with annual profit exceeding $10 million will benefit from the 20010 tax rate."

Jan 1, 1986

By John E. Udd

I N Part I of this paper, Professor Morrison suggested that our technique of causing cracks to develop around openings in a sheet of photoe1ashc plastic is, in effect, a laboratory-scale rockburst. Our investigations have indicated that the location and direction of these cracks are predictable, and that their growth can be controlled. On several occasions, we have been able to cause these cracks to propagate sufficiently slowly to be followed, with the naked eye. In practice, the rate of growth, gradual or sudden, would depend upon rock properties. This part of the paper presents an analysis of the stresses surrounding the openings before and after failure and also this author's views on the causes and after-effects of cracking. An attempt is made to correlate the stress patterns with those deter-mined from pure mathematics. Considering that the openings, except for the central enlargement, are long apertures with somewhat rounded corners, they might be compared with elongated ellipses having axes ratios of about 20:1 or with

Jan 1, 1963

By Jose A. Jimenez

"Mining operations generate an enormous amount of data that is difficult to organize, analyze and act on. These data require an extremely broad range of experts to investigate and manage the cross-disciplinary information. The data collects in paper files, diverse databases, historians, stand-alone applications, and excel files. This collection of sources represents everything from monthly, weekly, or daily inputs to real-time feeds or sporadic unscheduled entries. With the operational complexities ever increasing and fewer engineers per mine, an efficient operation is becoming more and more challenging. Engineers are typically burdened with data collection, clean up, and administrative efforts leaving very limited time for engineering assessment and/or optimization analysis. Often optimization becomes limited to the analysis of equipment uptime through existing field automation systems. A great portion of the field data is tucked away in historians seldom reaching those engineers who might leverage the data. Few mine operators have the time or budget to re-architect their operations data collection or management practice, so solutions must enable improvements without requiring expensive or time-consuming implementation. This presentation highlights examples where the aforementioned challenges are addressed using a solution framework designed to enable: 1) data integration and connectivity, 2) monitoring and opportunity recognition, and 3) engineering workflow automation. The initiative extends the concepts and success proven in the automation market segment to all disciplines across the mine operations. INTRODUCTIONThe mining industry by its very nature spends a great deal of its capital on equipment maintenance and replacement. In addition, periodic shutdowns due to equipment failure are typically very costly in terms of interrupted operations. Keeping mining equipment running at peak performance and avoiding costly shutdowns can make a huge difference in the overall return from mining operations. Today, information can be make available that can go a long way towards spotting equipment issues and permitting timely intervention to avoid costly unplanned shutdowns. That said, gathering all of the information from numerous points on many different pieces of equipment necessary to enhance overall equipment effectiveness presents its own daunting issues."

Jan 1, 2016

By D. K. Sarkar, Jiawei Xiong

"Self-assembled monolayers (SAM) on the aluminum substrates are used as the adhesion promoter between two aluminum substrates when bonded with the adhesive in adhesive bonding technology. Traditional surface analysis tools are not capable of identifying the presence of SAM on a surface; therefore, EIS has been used to determine their presence on the aluminum substrates. In this study SAMs have been deposited on aluminum using the monomer of (3-Glycidyloxypropyl)trimethoxysilane (GPTS) organosilane. AA6061 aluminum alloys substrates were chemically cleaned with NaOH and HNO3 to remove the native oxides, followed by immersion in silane solutions. In a second method, SAMs were prepared by applying a spin coating of silane solution to the samples. The prepared SAM coated aluminum samples were analysed by EIS in the three electrode corrosion cell using a diluted alkaline solution. The impedance of the SAM coated aluminum is found be higher than the as-received aluminum. It has been also observed that the open circuit potential (OCP) of the SAM coated aluminum is higher than the as-received aluminum. Both elevated values of the impedance and OCP confirm the presence of SAM on aluminum.INTRODUCTIONSelf-assembly (Schreiber, 2000) is defined as the spontaneous formation of complex hierarchical structures from pre-designed building blocks, typically involving multiple energy scales and multiple degrees of freedom. Generally speaking, SAMs are created by the chemisorption of ""head groups"" onto a substrate from either the vapor or liquid phase followed by a slow organization of ""tail groups"" of a molecule. Typically, head groups are connected to a molecular chain in which the terminal end can be functionalized with groups such as –OH, –NH2, –COOH, or –SH to vary the wetting and interfacial properties (Chauhan et al., 2007; Ulman, 1996; Vashist, Lam, Hrapovic, Male, & Luong, 2014). Though there exist several methods to prepare SAM (Chauhan et al., 2007; Chen, Yang, & Zhang, 2014; Cho, Park, Jon, & Choi, 2007; Igor Luzinov, 2000; Reis, de Melo, & Costa, 2006; Song, Zhai, Wang, & Jiang, 2006; Sugimura, Hozumi, Kameyama, & Takai, 2002; Vashist et al., 2014), the two methods vapor phase (Song et al., 2006; Sugimura et al., 2002) and solution(Chen et al., 2014; Igor Luzinov, 2000) are commonly used. Recently, many articles have been published on the fabrication of superhydrophobic surfaces with SAM technology (Cho et al., 2007; Pan, Shen, Shang, & Xing, 2012; Siddaramanna, Saleema, & Sarkar, 2014; Song et al., 2006). Brassard, Sarkar, and Perron (2011) successfully obtained a superhydrophobic film by applying fluoroalkylsilane via self-assembly on monodispersive silica. SAMs are also reported as good candidates for anti-corrosion and adhesion promotion (Chen et al., 2014; Saleema, Sarkar, Paynter, Gallant, & Eskandarian, 2012). However, papers on the characterization of SAM properties are rarely seen. The most commonly used substrate for SAM is silicon and the method implemented is scanning probe microscopy (SPM) such as atomic force microscope (AFM) (Igor Luzinov, 2000; Moores, 2011; Zhang, 2003, 2005). Igor Luzinov (2000) analyzed the epoxysilane SAMs’ surface morphology and microstructure properties using scanning probe microscopy (SPM) and ellipsometry on single-crystal silicon wafers. SAMs have been used to improve the adhesion bonding of aluminum or plastics but no characteristic data have been presented yet (Saleema et al., 2012; Telegdi, 2007; Wang, Xu, Luo, Wang, & Wang, 2009). Recently, Reis et al.(Reis et al., 2006) have studied SAM of alkane diphosphonate (Gardobond X4661) on Al 5052 alloy samples by EIS in a naturally aerated sodium sulfate solution."

Jan 1, 2016

Accountability for profit realized or lost, and responsibility for continued safe operation are the main impetus behind operator training. Efficiency in operation enables production at lower unit costs. An inefficient operation eats profitability of the operation, creating short term losses, and also affecting longer term viability particularly when commodity prices fluctuate and competition erodes market share. Safe operation and efficient operation are ultimately conjoined entities which may not be able to be sustained without dual effort. Training is a very valuable tool to engage operations in adopting more efficient and safe practices. Training requires time, facilities and trainers. One novel way of minimizing both the trainers and the facilities is through the use of Computer Based systems. Included amongst this are Computer based equipment simulators, following an identical philosophy as flight simulators used for pilot orientation and training for different aircraft types.

Feb 1, 2008

By J. F. Henderson, N. H. . C. Fraser

"Camlaren Mines, Limited, owns a group of claims near Gordon lake, in the Northwest Territories about 45 miles northeast of Yellowknife. The Hump vein on the property was explored continuously from the summer of 1937 to December, 1938, when all work was stopped. The two-compartment vertical shaft sunk near the vein is 380 feet deep and drifts and cross-cuts on the 200- and 350-foot levels total 2,241 feet . This exploration indicated 13,177 tons of ore with a gold content of between ½ and 1 ounce a ton1GEOLOGY AND STRUCTUREThe property is underlain by remarkably fresh greywacke and slate of the Early Precambrian Yellowknife group. The thickness of the b ~ds averages 1 to 2 feet, although that of the coarser greywacke may be 10 feet or more. Most of the greywacke beds show a gradation in grain from sandy at the base to slaty at the top. They are composed of chlorite, sericite; carbonate, and detrital quartz and feldspar grains.The structure of the greywacke and slate underlying a part of the property of Camlaren Mines, Limited, is shown in Fig. 1. The beds are isoclinally folded so that they dip at steep to vertical angles and at many places are overturned. The axes of the folds are 50 to several hundred feet apart, and generally plunge at angles of 45° or steeper. The beds along the axes of the folds generally meet to form a sharp V, and at the point of the V, or axial part of the fold, the beds are commonly ruptured . Minor faulting movements along the broken crests of the folds in many cases result in well-defined shear zones. Discontinuous quartz veins and irregular lens-like masses of quartz lying more or less parallel with the bedding are plentiful throughout the sediments, but tend to be concentrated along the ruptured and sheared, anticlinal and synclinal fold axes ( Fig. 1)."

Jan 1, 1954

By C. Samuelsson, G. Carlsson

Characterization of dust from Boliden Mineral AB’s copper-plant in Sweden was carried out using chemical analysis, X-ray diffraction analysis, energy dispersive analysis and wave length analysis using electron microprobe equipment. Dust from four different locations was characterized: the electrostatic precipitator (ESP) after the roasting furnace; the ESP after the copper smelting furnace; from the copper converter ventilation bag house filter; and from the bag house filter collecting dust from the settling furnace and tap gas ventilation. The results showed that the dust is composed of small solid and/or liquid particles from the furnace reactor which have been transported with the process gas to the dust collecting devices. This portion of the dust is mechanically formed. It also contains compounds that have been vaporized in the process and then condensed from the process gas at lower temperature, chemically formed dust. The proportion of mechanical and chemical dust varies with the process generating the dust.

Jan 1, 2001

By J. L. Dion

"A study of the techniques to integrally cast copper tubes in copper tuyeres for use in blast furnaces has been carried out. The work has been performed in support of current efforts to produce two-compartment tuyeres having improved water-cooling capacity. A test pattern corresponding to a vertical section of a two-compartment tuyere, and including a cast-in-place copper tube, was used to investigate such variables as tube preparation, tube coolant, pouring temperature, pouring rate and gating design. Successful castings, either with a good metalfurgical bond or good intimate contact between the tube and the casting, were produced, with all combinations of gating system and position of the tube tried. However, the pouring temperature, the pouring rate and the effectiveness of the coolant are interrelated and must be controlled to produce a good metallurgical bond.IntroductionAs part of its contribution to, and in collaboration with, the Copper Casting for the Steel Industry Committee, CANMET has undertaken research into the methods and techniques needed for the integral casting of copper tubes into high-conductivity copper castings.The objective was to produce two-compartment copper blast furnace tuyeres in which the water-cooled nose compartment consists of a copper tube metallurgically bonded to the wall of the high-conductivity copper casting. This design, developed in the UK, has demonstrated a much extended service life with attendant economies; unscheduled shutdown of blast furnaces due to tuyere failure is a significant problem in the steel industry. The Canadian steel industry believes that this design will replace the currently used single-compartment tuyere in blast furnaces within a few years.The technology to produce these tuyeres does not exist in Canada. One of the main features is the inclusion of a smooth-walled cooling channel in the nose, which permits high velocity cooling water to be employed. A second compartment acts as a reservoir backup, should failure in the nose occur. This would allow continued use of the tuyere for a period of time, permitting a scheduled shutdown for repair s. To assist the Canadian producers of tuyeres to maintain their market, and the Canadian steel industry to have a reliable domestic supply, it is important that the necessary technology for the production of two-compartment tuyeres be developed and transferred to industry."

Jan 1, 1982

By A. Jeffkins

Visibility is restricted when operating load haul dump vehicles resulting in a number of serious accidents in the Ontario Mining Industry. One of the leading causes of these accidents is the inability of the equipment operator to see clearly people, objects or hazards around the machine. Previous line of sight testing by the research team found specific machine characteristics were responsible for blind spots and impaired visibility. In order to identify feasible design modifications a computer simulation program, Classic JACK 3.1, was utilized. Program features include human factors analysis, which allows evaluation of line of sight and operator posture in order to decrease risk of musculoskeletal injury. Research within the virtual computer environment consisted of a Visibility Audit and a Target Audit in order to quantitatively determine how certain components of the LHD design affected the line of sight around the vehicle. Results indicate that modifying the LHD light brackets, engine profile, cab posts and other components will enhance visibility. The addition of cameras located on the front and rear of the vehicle were able to enhance the operator?s sight lines to previously obstructed areas. Modifications to seat height and the operators orientation both improved sightlines and decreased risk factors associated with back and neck musculoskeletal disorders.

May 1, 2003

By H. Huang, H. M. Chen, W. B. Xie

Cu-0.8Cr-0.1Zr alloy were prepared by atmospheric melting. the microstructure and properties of the CuCrZr alloy after first cold rolled, solid solution, second cold rolled and aging treatment were analyzed by using optical microscope, electrical conductivity analysis and Vickers hardness tester. The results show that with the increase of the first cold rolled deformation, the grain breakage becomes more serious, and the cold hardening becomes more obvious and the hardness increases. The conductivity and peak hardness of the first cold rolled (reduction of 30% and 60%) alloys after solution, secondary cold rolled and aging treatment reaches 81 %IACS and 187 HV, respectively. However, the conductivity in the CuCrZr alloy with a higher rolling degree (reduction of 90%) after solution, secondary cold rolling and aging treatment is significantly higher, and the conductivity and peak hardness is 85.8 %IACS and 178 HV, respectively. INTRODUCTION CuCrZr alloy has been widely used in domestic industry for its excellent comprehensive properties such as high strength and high conductivity, especially in the contact wire and lead frame of high-speed railway (Sun, Tao, & Lu, 2015; Mishnev, Shakhova, Belyakov, & Kaibyshev, 2015; Zhang et al., 2016; Fu et al., 2017). In recent years, a lot of research has been done on how to improve the strength and conductivity of CuCrZr alloy. However, the high strength and high conductivity of copper alloys are contradictory characteristics. On the one hand, the addition of alloying elements is conducive to solution strengthening and aging strengthening; on the other hand, too much alloying elements in copper alloys cause defects in the lattice of copper matrix, resulting in a serious decline in the conductivity of copper alloys (Martienssen & Walirmont, 2005). How to obtain high strength and high conductivity at the same time is the main problem. At present, the main research methods are adding microalloying elements, thermomechanical treatment and severe plastic deformation to study the electrical conductivity and mechanical properties of CuCrZr alloys. For example, Xie et al. (2011) added trace Ag to the Cu-0.26 wt%Cr-0.08 wt%Zr alloy, and the size of precipitated phase Cr and Cu4Zr became smaller and the mechanical properties of the alloy were improved. Su, Dong, Liu, Li, & Kang (2004) found that the addition of trace Mg in CuCrZr alloy inhibits the growth of precipitated phase and reduces the internal stress around the precipitated phase. At the same time, the size of precipitated phase becomes smaller and the peak aging strength of the alloy is improved. Pang et al. (2013) found that adding trace Ni and Si to the CuCrZr alloy could improve the peak hardness, softening resistance and precipitation morphology of the alloy. Experiments shows that the grain size was significantly refined by equal channel angular extrusion combined with aging treatment, while the strength of the alloy was increased, and the electrical conductivity of the alloy did not decrease (Vinogradov, Patlan, Suzuki, Kitagawa, & Kopylov, 2002; Saray, 2016); Kermajani, Raygan, Hanayi, & Ghaffari (2013) showed that the strength of CuCrZr alloy can be improved by rolling at 500 °C. After 150 minutes of aging treatment, the strength and conductivity of the material increased to 431 MPa and 81 %IACS, respectively. Takata, Ohtake, Kita, Kitagawa, and Tsuji (2009) noted that the strain hardening, uniform elongation and tensile strength of the nano-precipitates produced by the mechanical heat treatment process can be notable enhanced. The mechanical and electrical properties of CuCrZr alloy can be improved by combining large plastic deformation with aging treatment in the test process (Gao, Huttunen-Saarivirta, Tiainen, & Hemmila, 2003; Huang et al., 2003; Xia et al., 2012; Zel’dovich et al., 2014).

Jan 1, 2019

By Edgar A. Manker

"Today's market for columbium has only developed in the last two decades, and in this sense it is ""newer"" than molybdenum, vanadium and most other steel alloying elements. In this short period, it has assumed a very important role in steel alloying and in superalloys. From a few hundred thousand pounds of columbium in 1960, consumption has grown to nearly 30 million pounds per year, with a market value approaching two hundred million dollars.To assess the outlook for columbium, we will first consider the historical development of consumption and supply, particularly noting that all of today's major mines were developed during the last two decades. From current production, we will attempt to reasonably project the future. This future may well include new producers, particularly some producing columbium as a co-product with tantalum.The growth of current applications, and emerging new applications, will be considered with regard to future consumption and in relation to future trends in pricing.IntroductionThe nineteenth century was a busy time for the discovery and naming of new elements. Among those discovered were columbium in 1801 and niobium in 1844. Although it was later shown that columbium and niobium are the same element, the two names are still used today. Niobium has been pronounced the ""official"" name by the International Union of Pure and Applied Chemistry, but columbium is still widely used in commercial practice, and we have chosen to use columbium in this paper."

Jan 1, 1981

By F. Rosenblum, P. Spira

"A correlation has been established between the oxygen demand of Brunswick Mining and Smelting ore and flotation results at the bench, pilot plant and operating plant scale. A method of dete""1llining the aeration requirement of sulphide ores on the basis of this correlation is presented. It is shown that abraded iron from grinding media plays an important role in aeration and flotation. Laboratory grinding must therefore be conducted under controlled conditions with suitable grinding media in order to obtain the true aeration requirement of the ore.A method of evaluating aerator efficiency, also based on oxygen demand measurements, has been used successfully at Brunswick Mining to design pilot plant and full-scale aeration systems.1. IntroductionPre-flotation aeration of sulphide pulps has been practiced in the Noranda Group for many years to help in the depression of pyrite and pyrrhotite and to promote chalcopyrite and/or galena. Recently, two out of three parallel circuits at the Brunswick Mining and Smelting Corp. Ltd. concentrator have been converted on a test basis to a new flowsheet incorporating aeration as a basic step. Among other benefits, a substantial decrease in the middlings load has been achieved as a result of improved pyrite rejection. There has been increasing interest in other organizations in the potential advantages to be derived from' aeration in terms of improved metallurgy and/or decreased reagent consumption."

Jan 1, 1978

By S. Jeon, T. H. Kim

"Understanding the frictional properties of discontinuities is crucial to ensure the stability of underground structures. In particular, the frictional behavior at depth depends on the complex interaction among mechanical, hydrological, thermal and chemical characteristics and their coupled effects. In this study, a series of triaxial compression tests were carried out to investigate the behavior of rough shear surface of synthetic rocks. The frictional behavior showed little variation at different confining and water pressures. The test results were analyzed using Coulomb’s failure criterion. In addition, numerical analysis was carried out using PFC2D to simulate the test.INTRODUCTIONUnderstanding coupled behavior of rock at depth is of great importance in design, construction and operation of underground structures such as a disposal facility of radioactive waste, hot dry rock geothermal system and oil reservoir. In particular, many uncertainties are involved in characterizing deep rock mass deformation in the designing process and interactions among fluid flow of groundwater, high temperature and stress disturbance should be considered. Many independent studies have been carried out to investigate the thermal, hydro, mechanical and chemical coupled effects in numerical and experimental methods. They include the researches by Lockner, Summers, Moore and Byerlee (1982), Jafari, Amini Hosseini, Pellet, Boulon and Buzzi (2003), Tembe, Lockner and Wong (2010), Lee, Lee and Jeon (2012), Indraratna, Premadasa, Brown, Gens and Heitor (2014)."

Jan 1, 2015

By Gerardo Fuentes

Arsenic extraction from Chilean copper concentrates up to nearly 99% was achieved, using hydrothermal reactions. Arsenic appears in nature in more than 200 mineral species, being arsenopyrite (FeAsS), enargite (Cu3AsS4), and tennantite (Cu12As4S13) the most common species. In addition, arsenic is present in a large amount of copper concentrates, produced in northern Chile. Medical statistics show that in northern Chile, the amount of cancer to the lung, skin and bladder are the highest in the country. The latter situation, demonstrates the importance of studying metallurgical processes that do not generate atmospheric pollution. The hydrometallurgical processes such as hydrothermal treatment in autoclave reactors, do not produce gaseous emissions. On the other hand, the arsenic remains in solution from where it can be transformed in scorodite by widely known methods. Previous works about hydrothermal treatment of enargite have shown the feasibility of transforming the enargite of the copper concentrates into chalcocite or mineral species of the chalcocite family such as djurleite, digenite and for this reason enrich the concentrate in copper and pass the arsenic to solution. For this research, two Chilean copper concentrates were used, concentrate 1 with 5.5% arsenic and concentrate 3 with 1.8% arsenic. These concentrates were subjected to a complete chemical and mineralogical characterization. Later these concentrates were carry out to batch tests of hydrothermal treatment. Also, these concentrates were subjected to grinding to have different particle sizes. For the hydrothermal tests, a liter capacity Autoclave Engineer reactor was used. Characteristic of this reactor was the maximum temperature 350°C, 5000 PSI pressure, and 900 rpm agitation speed. Kinetic tests were carried out with the two concentrates maintaining the same solid: liquid relationship, the same agitation velocity and the variables studied were treatment temperature, time of reaction, concentration of copper in the solution and grain size of the concentrates. The conclusions of the study indicated arsenic extraction of the order of 93.98% from the concentrate 1 and arsenic extraction of the order of 98.74% from concentrate 3. After the hydrothermal treatment, the solids and solutions were characterized chemically, by electron microscopy and X ray diffraction. Also the solids were characterized by grainsize through a particle size analyzer (MICROTRAC). Results of batch treatment shows that arsenic can be release almost completely from real copper concentrates using this hydrothermal process and the next stage will be a scale up process in order obtain results for pilot plant design. INTRODUCTION Arsenic is an impurity that appears associated with copper minerals forming enargite, tennantite, tetrahedrite, and that due to the pyrometallurgical treatment either in conversion or roasting furnaces, it goes into the atmosphere together with the sulfur dioxide. A great quantity of literature can be found to eliminate arsenic or try to separate arsenic from copper. The methods used are mainly leaching processes with or without pressure (Padilla, Jerez & Ruiz, 2015) with different reagents like chloride media (Herreros, Fuentes, Quiroz & Viñals, 2003) or chloride media with sulphuric acid (Riveros & Dutrizac, 2008) or sodium hypochlorite (Mihajlovic, Strbac, Zivkovic, Kovacevic & Stehernik, 2007). It is known too that Chile is the first copper producer in the world and a great quantity of its minerals are in the north of the country, in Antofagasta.

Jan 1, 2019