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By E. Wright

"INTRODUCTIONThe Ruttan Mine is located twenty-two km east of Leaf Rapids in northwestern Manitoba. The copper-zinc exhalative massive sulphide deposit is comprised of a series of individual and interconnected en echelon lenses which strike east 20 degrees north and dip south 70 degrees. The mine has been owned and operated by the Hudson Bay Mining & Smelting Company since July 1987. Sherritt Gordon Mines Limited began mining the orebody in 1973 from an open pit, but production has been entirely from underground since 1980. HistoryDuring the progression from open pit to underground mining, it was recognized that manual methods of ore reserve calculation were inadequate for responding to changing metal prices and evaluating alternative mine plans. The mine planning system that was developed is described in the paper, ""Computerization of Ore Reserves and Mine Planning Functions at Ruttan Mine"", presented by B.C.W. Haystead at the 1984CIM Annual General Meeting. At that time, programs for core logging, diamond drill hole plotting, grade interpolation, ore outline digitizing, and reporting had been developed by the Systems Department for use on Sherritt's UNIVAC 1100 mainframe computer. Telecommunications linked terminals at the Ruttan coreshack and office to the UNIVAC in Fort Saskatchewan, Alberta. The same mine planning system was also used at a second property.Operation of the mine planning system was expensive, and it was evident that increased use required a costly upgrading of the UNIVAC in order to maintain an acceptable service level to all users. The system was re-evaluated,' and it was concluded that: core logging was not easily adaptable to a new property, nor flexible enough for exploration; plotting, grade interpolation, and digitizing required considerable manual effort; and that the UNIVAC operating system was difficult to learn.It was recommended that a study should determine if: core logging could be redesigned and/or implemented on a microcomputer; interactive graphics be used to reduce the effort for functions requiring visual interpretation; and the creation of input processors would assist users in setting up parameters for guiding the programs."

Jan 1, 1989

By C. A. Morais, L. V. Resende

"The technological development observed in recent years has stimulated the application of rare earth (RE) elements. Amongst their various applications it is well worth mentioning their use in electronics, superconductors, nuclear medicine, as well as in special inks - as those used in radar invisible airplanes. TV and computer monitor screens present as coating a powder containing some rare earth elements, mainly Europium and Yttrium. The recovery of the RE elements from electronic scrap is extremely important as the economic and environmental issues are concerned. This paper describes the study of the Eu and Y recovery from e-scraps. The first step of the process was the leaching of the powder obtained by manually scraping the inside surface of the screen. After the optimization of the leaching, the dissolution of Eu and Y was higher than 98 w/t% and a pregnant sulfuric liquor containing 11.9 g L-1 Y and 0.72 g L-1 Eu was obtained. The second step was the separation of the metals found in the liquor by the solvent extraction technique. The separation of Eu and Y was carried out in a counter current circuit compound of 3 extraction stages, 7 scrubbing stages and 15 stripping stages. DEHPA was used as the extractant, whereas a diluted sulfuric acid solution was applied as scrubbing agent and a hydrochloric acid solution at high concentration was used as the stripping agent.INTRODUCTIONThe rare earths (RE) are a moderately abundant group of 17 elements composed of lanthanides, scandium and yttrium. Amongst the RE, promethium (Pm) is extremely rare, however several of the RE elements are not very rare and occur dispersed in a variety of forms (Greenwood & Earnshaw, 1984; Tyler, 2004).The innumerable applications of the RE elements are based on their particular properties, mainly their spectroscopic and magnetic properties (Martins & Isolani, 2005). The technological development observed in recent years has stimulated the application of rare earth (RE) elements. They have been used in agriculture, electronics, superconductors, nuclear medicine, automobile industry, special inks – as those used in radar invisible airplanes, X-ray screens, high intensity mercury vapour light bulbs, neutron scintilators, charged-particle detectors and optical memory reading systems (Maestro & Huguenin, 1995; Nagaosa & Binghua, 1997; Sánchez et al., 1999)."

Jan 1, 2012

By S. W. Brooksbank, R. A. Benkis

"IntroductionThe Republic of Indonesia is a developing Southeast Asian country that unites the Indian and Pacific oceans, and spreads across nearly 14000 islands with a total land area of about two million km-. The distance across the country approximates the distance across Canada: Indonesia extends for more than 6000 km from the northern tip of Sumatra to the eastern border of Irian Jaya in the middle of New Guinea. With a population of around 180million, Indonesia is one of the world's most populous countries. A mix of 366 ethnic groups populates the country and there are some 250 distinct languages spoken. The topography of Indonesia generally is quite rugged because of its numerous volcanos. For example, the island of Java has 121 volcanos, of which 15 rise above 3000 m and another 44 reach heights between 2000 m and 3000 m.Indonesia has a diversified resource base, with plentiful energy resources (coal, oil, gas and hydroelectric), significant mineral deposits, large timber potential and a developed system of agricultural commodity production and export. A high proportion of the primary resources are on the sparsely populated islands of Sumatra and Kalimantan, whereas 7'3 of Indonesia's people reside on Java, or on 70/0 of the country's land area. Around Jakarta in western Java the population density is around 8000 per krn2. This contrasts with less than nine people per km- on Sulawesi (Fig. I)."

Jan 1, 1992

By Edward Rybinski

Compañía Minera Antamina is a polymetallic mining complex that produces copper and zinc concentrates as primary products and molybdenum and lead/bismuth/silver concentrates as by-products. In 2007, Metso Process Technology and Innovation (PTI) was contracted to increase SAG mill throughput by integrating and optimising blast fragmentation, crushing and grinding for the harder M4/M4A (CuZn) ores. Following the implementation of recommendations provided by Metso PTI, the SAG mill throughput increased from 2750tph to reach an average of 3600tph for the remainder of 2007. Due to continued application of mine to mill integration and optimisation philosophy, by 2010, the concentrator consistently exceeded the target of 4400tph while processing harder CuZn ores.

Jan 1, 2012

By T. Guan, G. Fu, X. Zhou, L. Deng

"Currently, tailings water is required to be recycled in minerals processing plants. When the flotation tailings water of complex copper-sulfur-tungsten polymetallic ore is reused to the flotation of copper-sulfur ore, a portion of tungsten would be lost in copper concentrate or sulfur concentrate due to the addition of the collectors used for oxidized ore which are also effective for the sulfide minerals in the process of tungsten flotation. At the same time, the technical index of copper concentrate and sulfur concentrate would be seriously affected by tailings water. Our experimental researches of many years show that the copper concentrate with a grade of 18.36% Cu at a recovery of 76.67% is obtained for the raw ore containing 0.60% Cu, 18.99% S, 0.16% WO3 in small locked cycle test using recycled water, through simple pretreatment of the tailings water from tungsten flotation and adding special regulator CW and new tungsten collector TM. The result is close to the performance without using tailings water. And, in the continuous pilot experiment which was continuously conducted for 4 days with the same technology, the following results was obtained: the copper concentrate with a grade of 21.74% Cu, the recovery was 71.55%; the sulfur concentrate with a grade of 45.16% S, the recovery was 80.10%; the tungsten concentrate with a grade of 42.63% WO3, the recovery was 54.62% relative to raw ore (the recovery relative to scheelite was 76.47%). The throughput of the continuous pilot experiment is 1.0~1.2 t/d, and the raw ore contains 0.56% Cu, 18.80% S, 0.14% WO3 on average.INTRODUCTIONMining industry is one of the most important developing fields, it supplies raw materials for industrial production as well as discharges much waste water. Tailings water is the main source of beneficiation waste water, it would result in severe environmental pollution if discharged directly. Generally, the tailings water would bring undesirable effect on flotation index after simple pretreatment by lime (Kalin, Fyson, & Wheeler, 2006). On the other hand, the treatment of tailings water through ion-exchange (Cui & Liu, 2015) before recycling is of high cost. Generally, in the flotation of Cu-S-W polymetallic ore, when the tailings water from tungsten flotation is treated simply by lime and recycled to the flotation of sulfide minerals, the flotation index of sulfide minerals decreases, and a portion of oxide mineral would be lost in the sulfide concentrate. As a result, the recycle rate of this kind of tailings water is relatively low, some of the tailings water is discharged after simple treatment and then environmental pollution is caused subsequently. One of the effective ways to improve beneficiation performance and increase the recycle rate of tailings water is to conduct research on developing recycle technology for flotation tailings water of complex copper-sulfur-tungsten polymetallic ore."

Jan 1, 2016

By Jeffrey T. McGinty, Frank M. Wheeler

Plant layout is the arrangement of equipment, process areas, departments, infrastructure, and support facilities. Plant logistics is the flow of parts, people, resources, and information throughout the production process. This chapter: outlines key factors and provides checklists to facilitate layout development; presents risk management approaches to test the logistics and functionality of alternative layouts; and uses real-world examples to illustrate effective simulation modelling to assess plant layouts.

Jan 1, 2015

By D. A. Whitley, R. P. Carone

"Shaft sinking by blind shaft drilling offers the mining industry a different approach to shaft construction. Benefits of blind drilling include less construction time and fewer safety problems while being economically competitive with conventional sinking methods under certain conditions in soft water-bearing formations.Technology and equipment are available today to drill blind shafts up to 20 feet in diameter and over 3,000 feet deep. This is an extension of proven techniques developed by private industry. To drill a 20-foot-diameter hole requires a specially manufactured hydraulic drill unit with a rated hoist of 2 million pounds and 500,000 ft/lb of torque.This brief paper will discuss the following aspects of blind shaft drilling:• benefits;• equipment f or drilling;• circulation methods;• circulation rates;• shaft alignment; and• progress rates to be expected.IntroductionShaft sinking by blind shaft drilling offers the mining industry an improved alternative method for shaft construction. The drilling of 20-foot -diameter shafts to depth s in excess of 3,000 feet can be done by utilizing equipment specifically designed and manufactured for this purpose. This equipment is a distant cousin, at best, to standard oil well drilling rigs. The actual configuration of these drilling machines will be discussed in a following section.To most people, the drilling of mine shafts may seem to be a new or at least recent technology. However, as early as the I920s, German and Dutch miners were drilling 24-foot diameter shafts for coal mines. What led ""miners to resort to drilling were ground conditions that still plague conventional shaft sinkers today: soft , water-bearing formations. The major drawback to these early attempts was a low penetration rate due to poor bit cleaning. This, however, was not the end of early shaft drilling activity. From 1936 to 1950, a number of mine shafts were drilled by the calyx or coring method. This method employs a bit with a large bore down the center. As it drills, it cuts a core. When 5 to 10 feet have been drilled, the core is removed. The disadvantages of this method were the time and work involved in breaking the core free, and it was inadequate in soft water-bearing ground."

Jan 1, 1981

"Real-time, on belt analysis of minerals is becoming increasingly important and critical in modern operations, especially in the mine-to-mill. Prompt gamma neutron activation analysis has long been utilised for real-time elemental analysis in bulk materials, with Scantech's GEOSCAN being the instrument of choice in the minerals sector. Working in the minerals space for 15 years, the GEOSCAN has been successfully implemented in a wide range of minerals applications including iron, copper, lead-zinc, manganese, phosphate and more, and it caters for the very high demands and increasing requirements of a contemporary processing facility. An area of focus has been on increasing the analysis frequency to allow for rapid analysis results with the same high degree of accuracy typically expected of the GEOSCAN. This paper discusses the underlying research and technology that has enabled such rapid analysis and presents a range of examples using a thorough statistical approach on real production material, demonstrating achievable accuracy over a short analysis time, and dispelling common myths about the speed of the technique. Potential applications are discussed to conclude the paper.INTRODUCTION Technology and the information it can provide plays a critical role in the evolving modern mineral processing landscape. The importance of technology to analyse various features of ores and concentrates being processed is obvious, and recent years has seen the advance of numerous technologies to provide a variety of real-time measurements on conveyed material flows. From sampling apparatus to particle size analysis to weight and density meters to full elemental analysis, the availability of information enables a variety of improvements in the process leading to improved efficiency and increased revenue. To maximise the potential benefits, access to real-time information is imperative, and rapid updates of information become necessary to make appropriate process control decisions based on the most relevant and up-to-date information."

Jan 1, 2017

By S. Nafisi

Permanent mould casting may be regarded as a near net shape manufacturing process where simple to very complex shaped engineering components are fabricated with high degree of precision in a metallic mould, In this group, High Pressure Die Casting (HPDC), have attracted more attention because of its production rate, where both liquid and semisolid metals (SSM) can be cast with high degree of precision and versatility. The SEED process, Swirled Enthalpy Equilibration Device, the new process for semi solid metals slurry production route, consists of two steps: The initial step involves extracting specified amount of heat from the molten metal to generate liquid-solid slurry, i.e, mushy structure, followed by drainage of remaining liquid to produce a compact free standing feedstock for rheocasting operation. In this paper, microstructural evolution during the process and some initial casting results of automotive components an also reported.

Jan 1, 2005

"Pilot plants for pressure hydrometallurgy represent special design and project execution challenges. Over the past twenty years, Zeton has designed and fabricated a variety of world-class pressure hydrometallurgical pilot-plant facilities for the nickel industry, and this paper discusses design considerations and strategies related to such projects. Project execution methods are also discussed, and guidance is given for the selection of materials of construction and for the selection of appropriate pressure and temperature design points for pressure hydrometallurgical pilot equipment. The paper concludes with a discussion of the need for process similarity with future commercial operations and the realities of pilot-scale equipment.INTRODUCTION The process technology developer or owner and the designer/fabricator of a new pilot-plant facility are faced with some difficult technical choices even after the decision to build a dedicated plant has been taken. A pilot-plant project is usually on the critical path of a large commercial project involving investments many multiples greater than the capital cost of the pilot plant. Schedule savings in the design, manufacture, and commissioning of the pilot plant or in a rapid completion of the experimental program can be disproportionately beneficial to the overall development project. However, inappropriate shortcuts resulting in major oversights can be disproportionately problematic. A number of considerations and suggestions for both the project execution approach and the process engineering design of pressure hydrometallurgical pilot-plant facilities are presented as a guide for potential owners and operators of new pilot-plant equipment and facilities. These suggestions are particularly applicable to the nickel industry, where the majority of our firm’s prior hydrometallurgical experience was obtained. This paper is an update to an earlier publication (Martin, 2004), offering an opportunity for a new generation of metallurgists and engineers to learn the specialist requirements of pilot- and demonstration-scale plant design, which are key functions in the development and commercialization of new processes."

Jan 1, 2017

By C. Edwards

ABSTRACT: Milling operations in northern Saskatchewan’s Athabasca Basin have produced uranium continuously since 1975. During that period, the Athabasca Basin has been one of the world’s premier uranium camps, yielding more than 660 million lb (299,370,964 kg) of U3O8. In this paper, the author describes former and current milling operations and discusses why and how the milling process has changed and developed over the past 35 years. The author’s considerations for the future of uranium extraction in the Athabasca Basin conclude the paper.

Jan 1, 2012

By R. Esteban, D. Runnels, J. Torrealba-Vargas, G. Couture

"Data handling is an important step in the development of a simulator of a mineral processing circuit. The model requires representative data of the scenario to be modeled. The model development involves protocols that must be followed very closely to complete a successful project.Data handling of large and diverse datasets (metallurgical test results, geological data, mining models, historical data, etc.) is a key element of the model. The information needs to be processed, reconciled, interpreted, modeled and presented to support the design or the optimization of a mineral processing plant.Best practice recommends that teams from different disciplines (such as mining, metallurgy, geology and environmental) interact to define the most important variables that could influence the simulator. For example by adopting a geometallurgical approach in the earlier stages of the project, it is possible to consolidate the number of main ore rock types in a testwork program (saving money and time) by involving geologists and metallurgists in the sample selection and data interpretation.Planning the development of a model involves an understanding of the software capabilities but also the limitations and the magnitude of the data required to calibrate the model in case of changes in the project.A successful model requires a deep understanding of the circuit to be modeled and thus plant personnel should be considered as members of the team.This paper describes the use of the "state of the art" tools for data analysis, simulation and optimization; and shows three practical examples of the use those tools in the design of mineral processing plants."

Jan 1, 2015

By R. I. Kraydenko, A. N. Dyachenko

"The possibility of SiO2 5N production by staged purification of ammonium hexafluosilicate (NH4)2SiF6 is discussed. High-purity silicon dioxide can be obtained with fluoridation of quartz concentrate by solid NH4F at 100 °C, with further sublimation of the product at 320 °C, its dissolution, ammonia hydrolysis, filtration and drying of SiO2•nH2O. This is accompanied by regeneration of the processing reagent - NH4F.INTRODUCTIONProduction of high-purity silica-5N (SiO2 content over 99.999%) is an important and urgent task of the modern chemical industry. This material is used in the manufacture of optical glass, optical fibers for internet cables, silicon for solar power and electronics.Quartz concentrate is raw material for the production of silicon dioxide. The existing technologies of synthetic silicon dioxide were introduced in the mid-twentieth century. These methods are energy-consuming, multi-step and do not meet stringent environmental requirements. In fact, as some conventional technologies became obsolete; it became necessary to develop new methods for the production of synthetic silica. We believe that the fluoride technology of processing of quartz materials by ammonium fluoride is the most promising direction.In industry, silicon dioxide marked ""Silica White"" is obtained by liquid-phase method. The method consists of the precipitation of amorphous silica from sodium silicate solutions with acids. The resulting product is filtered, washed and dried. Depending on the deposition conditions and nature of the coagulant the ""Silica White"" is acidic, neutral or alkaline. The dry product is subjected to grinding. The degree of dispersion and porosity of the particles of Silica White depends on the nature of decomposition agent (a substance that decomposes the silicate) and coagulant, conditions of sedimentation, filtration and drying. During the drying process the silica particles are sintered into aggregates of a few millimeters."

Jan 1, 2012

By E. S. Allen, P. R. Kruesi, J. L. Lake

An electrochemical process is described for converting concentrates of base-metal sulphides to the corresponding pure metals and elemental sulphur. The application of the process to chalcopyrite is discussed. The process is also of potential interest in processing copper-nickel sulphides, and laboratory data concerning this potential are presented. The process creates neither air nor water pollution.

Jan 1, 1973

By D. H. d Hamly

THE work of Brown and others at Pittsburgh (Brown, Baum, Yant, and Schrenk, 1938)(1) and the success of their light field microprojector (Figure 1), have shown that the microscopy of dust quantitation can be greatly improved. It has been shown that dark-field microprojection of dust spots on konimeter slides is possible (Pullen, 1940), and this paper is a discussion of the new microprojector and a new counting method which is made practical by this instrument. The microscope makes possible the ready determination of the dustiness of mine ventilation air. Reduction of the dust concentration from a dangerous to a safe level involves one or more of the following: reduction of dust production, filtration of the air stream, or dilution with non-dusty air. Each of these raises important engineering problems of time and costs, and trustworthy information on the state of dustiness of the air is required ?both before and after the employment of any method of reduction. Records of this information may be divided into two broad classes concerned with safety: (1) the level of dustiness, and (2) the quantity and kind of dust produced by a machine under a given set of conditions. Though the first requires only one determination for a given time and place, numerous routine records are required to show the continuous safety of the air in an actively producing mine. Though repeated samples are required, highly accurate counts are not needed to show safety or to indicate whether a substantial increase in the non-dusty ventilation air has produced a proportionate decrease in the dustiness of the mixed air. The Devers and Gathercole konimeters have proved satisfactory instruments for this purpose in Ontario.

Jan 1, 1942

By Nitin Bhavsar, Kaushik Vakil, Lakshmikanth Reddy, Sanjay Sarkar, Tathavadkar. Vilas, Bhavin Desai, Raghavendra Adiga

Gold and platinum group metals (PGM) do not dissolve in sulfate electrolyte from anode during electro-refining of primary copper. The PGM form solid ‘slimes’ which accumulates at bottom of the electrolytic cell. Typically, 8 to 10 ppm silver is present in copper cathodes, which is equivalent to almost 2% of silver loss during electro-refining. The silver can be cemented with cathode copper as soon as it is dissolved into the electrolyte from anode or during entrapment of slime particles in cathode. Over a period of time, the concentrates grade has deteriorated and change in type & amount of impurities in concentrate has resulted in higher silver loss during refining process. Therefore, an in-depth investigation was carried out in both fire- and electro-refining processes to understand the root causes of higher silver loss in copper cathodes. The detailed characterization and the plant data analysis were carried out. The results of study revealed that higher silver loss in 3rd crop cathodes as compared to 1st and 2nd crop cathodes from same anode. In anode silver was present in two forms, dissolved in copper (solid solution) and in slime phases such as Cu2-xAgxSeTe. SEM-EDX study of anode cross section confirmed higher silver and oxygen content in central region (core) of anode as compared that in both air and mold sides. This is due to non-uniform cooling of anode which was confirmed by the solidification modeling. Higher concentration of oxygen & silver at core of anode rised Ag+ concentration in electrolyte and slime particles during 3rd crop. The results of study were used to optimize the anode cooling process and also electrolyte chemistry to reduce the silver loss. The details of study carried out are discussed in this paper using the results of modeling, characterization and experimental studies. INTRODUCTION In the electrolytic refining of copper, fire refined copper anodes are used as raw material. Anodes contains copper of the range 99.5 to 99.6%, rest being the impurities. Hence, the purpose of the refining is (1) to remove the impurities so that final cathode conforms to the LME specifications and also (2) to recover the precious metal from the anode copper. When anode is dissolved, most of the impurities reports to the anode slime settled at the bottom of the cell, and rest dissolves in the electrolyte. Dissolved impurities remains in electrolyte and are removed during electrolyte recycling. However, sometime dissolved impurities and slime particles get entrapped in cathode due to disturbances in operational conditions. Metals dissolving in the electrolyte are the elements such as Ni, Co, Fe, Zn. The electrode potential of As, Sb and Bi being close to that of copper, these elements partly dissolve in the electrolyte. Noble metals like Ag, Au, Pt and Pd are generally insoluble and are thus expected to report to the anode slime. A small amount of the sliver content from the anode is dissolved in the electrolyte. Because the dissolved silver electroplates on the cathode at a smaller applied potential than copper, the cathode typically contains up to 8 ppm of silver. This is referred to as ‘silver loss’ in cathode (Cooper, 1987). Fortunately, silver is a rather benign impurity in copper due to its electrical conductivity being higher than copper. However, higher silver loss in cathode is loss of revenue for Copper smelter due to significant difference in their LME price.

Jan 1, 2019

By V. Concha, M. Hashemzadeh

"The objective of this study was to gain a better insight into the kinetics of chalcocite leaching in an acidic ferric sulfate media. Chalcocite leaching in acidic media is known to occur in two sequential stages, with the first stage being much faster than the second. The leaching residue from the first stage is typically assumed to be a covellite type of material. This study hypothesized that the mineralogy after the first-stage leaching varies in response to different leaching conditions. We investigated the dependency of the mineralogy of the first-stage leaching residue on temperature and initial ferric concentration. The experimental results showed that chalcocite leaching behavior altered upon temperature and initial ferric concentration. A proposed combined reaction model was found to be able to describe the experimental data. The first stage was described very well by the shrinking core diffusion model while the second stage was described very well by the shrinking core chemical reaction model. This finding has important implications for mine operations to manipulate leaching conditions to create the desirable leaching kinetics.INTRODUCTION The kinetics of chalcocite leaching in sulfate media has been extensively studied (Cheng & Lawson, 1991; Fisher, 1994; Fisher, Flores, & Henderson, 1992; Niu, Ruan, Tan, Jia, & Sun, 2015). Sullivan (John D. Sullivan, 1930) proposed a two-stage process for chalcocite leaching in an acidified ferric sulphate solution. The two-stage leaching of chalcocite is presented as the following reactions:"

Jan 1, 2017

By L. Lamothe, C. H. The

"Pilot precipitator tests were conducted at Noranda's Horne Smelter in late 1978 to evaluate methods of improving converter dust collection efficiency. A bout 35 Nms/min. of converter off-gas were isokineticatly diverted from the converter flue to the pilot precipitator leased from Flakt (Canada) Ltd., consisting of three fields, one transformer-rectifier set per field and 77-m2 total collecting plate area. The effects of gas volume flow rate and conditioning the gas with sulphur trioxide and/or additional moisture were tested. II was found that gas flow rate and moisture level had the most pronounced effect on collection efficiency. Based on a techno-economic assessment of different options for improving converter Courell efficiency, waffle hoods and water sprays were installed on the converters to reduce air infiltration and increase the moisture level in the gas.BackgroundThe Horne Smelter of Noranda Inc. is situated in northwestern Quebec and, since the closure o f the min e in 1976, has been operating as a custom smelter. The concentrates treated at the smelter come from various mines with mixed sulphide ores , many o f them containing significant amounts of lead and zinc which makes dust collection in electrostatic precipitators mo re difficult than normal.As part of a continuing program on reducing smelter dust emissions, the No . 6 Cottrell was installed in 1972 up stream of Nos. 2 and 4 Cottrells (in parallel) in a n attempt to improve dust collection by increasing the over- all precipitator capacity ( Fig. I). However, it has never per formed a t its designed efficiency o f 94%. The average efficiency established in various test s was in the range of 60 – 65%."

Jan 1, 1985

By T. Feldmann, G. P. Demopoulos

The feasibility of chloride leaching processes depends on interfacing them with cost-effective HCl regeneration technologies. This paper summarizes the most important findings of research conducted in the past 3 years concerned with a novel process to regenerate high-strength HCl from concentrated CaCl2 solutions at temperatures below 100°C, via reaction of CaCl2 with H2SO4 resulting in the formation of calcium sulfate phases (gypsum, a-hemihydrate or anhydrite). From constant supersaturation semi-batch experiments in pure solution it was found that the crystal growth rate of hemihydrate, and hence the particle size, was influenced by the rate of reagent (Ca2+, SO4 2-) supply to the reactor. Additionally, growth studies of DH in presence of impurities (K+, Mg2+, Sr2+, Ba2+, Fe2+/3+, Al3+, La3+, Y3+, F- and PO4 3-) showed that specifically Sr2+ and PO4 3- are taken up during crystal growth. Furthermore, it was found that decreasing water activity (via different HCl/CaCl2 concentrations) and increasing temperature reduce the metastable life-time of DH and HH by increasing the phase transformation speed. The DH/HH transformation was identified to be dissolution-precipitation based, while HH to AH is a topochemical process. Finally, continuous experiments on bench scale are underway to confirm the feasibility of the process to obtain super-azeotropic strength HCl with up to 9 mol/L (~30wt.%) from 5 mol/L CaCl2 (~40wt.%) solution.

Jan 1, 2014

By C. S. Crocker

The Centennial orebody was discovered and named in 1970, Manitoba's centennial year. It is relatively small, about 2 million tons. Strike length varies from 400 to 600 feet and widths from 10 to 60 feet; dip is 75 degrees. Low grade and metal prices demanded low-cost mining, and the mine was developed for conventional sublevel stoping. As the ore lay entirely under a large lake, ground movement had to be avoided and the stopes were to be filled hydraulically. Late in 1973, vertical crater retreat mining was introduced at Inco Limited, Sudbury, to recover pillars between filled stopes. It proved satisfactory and the results were publicized by CIL, who developed the technique. The method seemed to offer some advantages and one stope at Centennial Mine was selected to be mined by VCR while production was maintained from blasthole stopes. The trial stope was safe and showed lower development costs, reduced drilling time, a favourable powder factor and good fragmentation. VCR mining is now an accepted method at HBM&S Co., Ltd., and its use is being extended.

Jan 1, 1979