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By V. G. Papangelakis, G. A. Moldoveanu

"One of the major commercially viable secondary sources of rare earths elements (REE) are the ion-adsorption ores, containing 0.05-0.3 wt% rare earth oxides physically adsorbed on the surface of clay minerals formed during weathering of lanthanide-rich rocks. Although ion-adsorption deposits are substantially lower grade than other types of rare earth sources, this is offset by the easier mining and processing costs and the low content of radioactive elements. The conventional extraction route involves ion exchange leaching with monovalent cation solutions (usually ammonium sulphate) under ambient conditions; during the process, the lanthanides are desorbed and transferred into solution, being replaced by the exchange cation. While ammonium ions are known to perform best, there is increased environmental motivation to investigate alternative lixiviants in order to minimize ammonium sulphate impact via reducing its use without considerable loss in rare earth recovery.The objective of the present research was to screen various cations salts (alkaline and alkalineearth metals present as sulphates, chlorides and acetates, respectively) in order to comparatively evaluate lanthanide desorption levels and provide a theoretical base of the observed behaviour. The overall aim is to gain a better understanding of how both cation and anion may affect the overall REE recovery from ores in order to provide alternative processing routes. The distinct exchange capabilities of cations were explained in terms of differences in cation hydration enthalpy within the same group, i.e. Cs+ > NH4 + > K+ > Na+ > Li+ and Ba2+ > Ca2+ > Mg2+. For the same cation, it was determined that REE extraction efficiency follows the order sulphate > acetate > chloride, based on dissimilarities in constants of formation values. Various process implications scenarios will be described based on using mixed cations and anion matrices."

Jan 1, 2016

By Alan D. Akerman

This paper describes the significant advantages and improvements in operational availability, reduced breakdowns, and overall cost reductions that can be achieved through the application of a Reliability Centred Maintenance (RCM) program, including Condition Based Maintenance (CBM) and Equipment Health Monitoring (EHM), in a mine environment. It uses a case study to illustrate the essential elements that constitute the basic requirements to establish such programs. This CBM case study analyzed the Load-Haul- Dump (LHD) vehicle sub-systems and their dominant failure modes, as a precursor to the development of condition indicators. The case study describes a disciplined process to enable condition indicator development and qualification in support of a CBM program. The identified condition indicators vary from readily applicable off-the-shelf monitoring systems and techniques, through to "leading edge" technologies that require further research and development. The paper also explores the developments that have been made in the combination of expert system software associated with modern computer based control systems, and the availability of "intelligent? sensor technology that complement the control system capability.

May 1, 2002

By Caroline B. Chapleau, Mélanie Proulx, Claude Bazin, Gaétan Lavoie

"Quebec Cartier Mining operates a pelletizing plant in Port-Cartier, QC. Grinding, agglomeration and pellets induration are the three main steps in the preparation of iron oxide pellets. In 1998, following different recommendations, the company increased the speed of one of its ball mill in order to increase the grinding efficiency of the machine. As expected, the increased speed lead to an increase of the power draught, which did not produce the expected increase of fineness of grind, neither its allows to increase the mill throughput. The change of behaviour of the mill could hardly be understood by comparison of discharge size distribution at initial and modified mill rotation speed. On the other hand, the use of the selection function from a population balance model provides an insight of the changes that occurred in the mill. This paper reviews the various steps required for the estimation of a grinding mill selection function. Results of the calibration to Quebec Cartier grinding mills show that the increase in the mill speed leads to higher rate of breakage of coarse particles, at the expenses of less efficient breakage of medium and fine size particles. In the case of the studied mill, breakage of coarse particles was probably not the critical step of the mill operation. INTRODUCTIONOre size reduction is the major energy consumption step in any mineral processing operations (Austin et al., 1984). Size reduction is required to either liberate valuable minerals from the gangue minerals in which they are imbedded, or to increase the specific surface of the ground material. Plant engineers continuously face the challenge to find grinding machines, operating conditions or grinding circuit flowsheet configurations that could improve the size reduction process at lower energy or m6dia consumption."

Jan 1, 2000

By B. Yu, N. Verbaan, A. Mezei

The recent 20 years witnessed a boom and bust in the nickel laterite industry. Most notoriously is the story of the first three Western Australian nickel laterite projects which all suffered major ramp-up issues. Many hard lessons were learned by the industry and it has been widely reported that the major contributing factors included insufficient testing as well as a limited understanding of the materials handling characteristics at the front-end stage of the flowsheet. This paper compares the current "race to production" in the REE industry to the laterite industry 20 years ago and addresses the fundamental question: ‘Have mining and exploration companies with rare earth projects learned from past lessons and are they doing sufficient and appropriate testwork to prevent failure’? The authors will provide the perspective of a commercial metallurgical laboratory that has gone through the laterite cycle and is active in the present REE cycle.

Jan 1, 2014

By R. Clarkson

"Free gold particles occur in many base metal and precious metal mines throughout the world. Due to the high density and malleability of gold, large circulating loads of free gold particles can build up over time in grinding circuits. This gold is often deposited in unintended traps throughout the mineral processing system.These unidentified free gold deposits represent a serious security risk as well as an inaccessible inventory of gold. Deposits of free gold particles often remain undetected by mine management until they are accidentally discovered while repairing mill equipment.Nuclear tracers have been used to determine the free gold recovery efficiency of gravity recovery equipment, drills, and sampling equipment (Clarkson, 1994, 1995; Walsh and Rao, 1986; Walsh and Kelly, 1992). In November, 1993, the author inspected the grinding circuit at La Mine Doyon in Rouyn-Noranda, Quebec and made recommendations to recover coarse gold and to eliminate gold traps from the circuit. In 1995, the author salted mineral processing circuits with radioactive gold particles. The gamma and X-ray radiation from gold’s nuclear isotope (Au198) were detected through steel, in pipes, and in moving equipment using scintillometers. The radiotracers proved to be a safe, rapid and accurate method of identifying gold traps and improving security.Nuclear TracersWhen particles of gold are placed in a nuclear reactor, some of the gold atoms (Au197) absorb another neutron in their nucleus to form gold’s radioactive isotope (Au198). In the process of radioactive decay, this isotope emits high energy gamma rays and X-rays which are easily detected (even through steel) with scintillometers.Radioactive gold (Au198) has a very short halflife of 2.7 days. At the relatively low activity levels used for tracing, the particles remain detectable with a small hand-held scintillometer for about 10 to 14 days. After 14 days the irradiated gold is close to background levels and within two months it is essentially non-radioactive. The radiation has no effect on the recovery characteristics of the gold particles. The gold radiotracers are very safe due to their very low level of radiation, short half-life, and their inherent physical and chemical stability. However, the use and possession of even mildly irradiated gold is strictly licensed and regulated."

Jan 1, 1997

By H. Saari, M. Pates, P. C. Patnaik, A. Merati

Single crystal nickel-base superalloys such as PWA1484 exhibit superior performance compared to conventional superalloys, and are used extensively in turbine blade applications requiring good high temperature properties. The life of these blades is typically limited by cracks and erosion. Due to the high cost of these blades, welding techniques are being considered to weld/repair worn components, extending their useful lives and delaying the need for expensive replacement components. However, the sensitivities for solidification cracking and post weld heat treatment cracking are relatively high in these alloys. Electron beam (EB) welding can deliver concentrated heat sources and has the potential to address these issues. Numerous welding trials and structural tests must be conducted to identify the optimum method and welding parameters. Weldability is studied over a range of material conditions, welding parameters, and directions. The influence of welding parameters on the fusion zone microstructure and resultant weldability is investigated using combination of microscopic examination and micro-hardness testing. This paper summarizes some of the results of a feasibility study conducted to understand the effects of welding parameters on localized microstructural features, cracking sensitivity, and mechanical properties of autogenously EB welded coupons of single crystal PWA1484.

Jan 1, 2004

By Michael J. Beare

Requirements of both local permitting and international fundraising are forcing increasing numbers of projects in Russia and CIS to carry out dual technical studies. The principal focus of Russian mining project design is to satisfy local regulatory requirements. However, the technical documents are not generally accepted by international banks for project finance outside Russia. Similarly, international study documents are not accepted for permitting in Russia. The purpose of this paper is to compare and contrast Russian and international approaches to mine technical studies and draw conclusions from this. The Russian design and permitting system is centered around two key statutory technical documents termed the TEO Konditsy and the TEO Project. These documents are subject to regulatory approval and are broadly equivalent to the international prefeasibility study and the feasibility study respectively. A comparison of study criteria suggests similar approaches are used for the main technical disciplines in project design by the time projects are at the point of construction, but there is divergence on environmental matters where the OVOS (Russian ESIA equivalent) differs from an ESIA in some significant areas. The key differences relate to project footprint, level of technical detailed required for baseline studies, level of public consultation, consideration and disclosure of information, labour, coverage of community and social issues and the preparation of a Social and Environmental Management System (SEMS). It has been noted that the Russian Design Institutes often leave the detailed economic analysis until after the TEO Konditsy. A common problem is design teams tend to look for ?technological solutions? without due concern for project economics. The end result of this can be mines that are overcapitalized and hence sub-optimal. It can be concluded that Design Institutes have the monopoly on Russian permitting reports and this is likely to continue. Similarly, Russian institutes generally do not prepare feasibility studies to international standards and this is likely to continue to be the case. Therefore to achieve the requirement of dual technical studies, the international consultants and Russian Design Institutes will need to cooperate on a joint work program. Key issues will be to ensure the most appropriate option studies are carried out at the right stages, that project economics are considered throughout the study, and that the environmental work program covers the additional studies necessary for the ESIA.

May 1, 2009

By W. G. Worcester

IN the presentation of this paper to the Institute, three objects are in the mind of the writer: first, to set forth the close relation which, of necessity, exists between ceramics and the industrial minerals; second, to clarify the apparently hazy understanding which many have of ceramics in general; and lastly, of equal or even more importance, to stimulate a greater interest in the industrial minerals, especially in those used and required by the ceramic industries. While Canada is now producing in large quantities a fairly wide variety of the ceramic industrial minerals, there are some which are not known to occur in the Dominion. Hence it is to be desired that our geologists, prospectors, and others, while on field work, should be on the look out for commercial deposits of such minerals as diaspore, bauxite, ucts of a value in excess of $600,000,000, a figure which places ceramics as kyanite, massive topaz, and sillimanite. A find of any of these in quantity would prove of very great importance and value to the country as a whole. At this point it seems desirable to introduce formally the word ceramic or the plural of it, ceramics. In doing so it may be stated that the origin of the word dates far back in history in that it was derived in part from the Greek word Keramos, 'a potter' or 'pottery', which in turn has been traced back to an older Sanskrit root meaning 'to burn' or 'burned stuff', having reference, no doubt, to burned pottery or other clay wares; and the word was so used until near the close of the last century, when the world's first schools of ceramic engineering were established in the United States. The use of the term ceramics was then expanded to cover a much larger field the entire field of the silicate industries and products. At one time it was suggested by a limited number of ceramists that the term 'ceramic engineering' be changed to 'silicate engineering'. This proposal, however, gained little support and was soon abandoned.

Jan 1, 1945

By Dayang Datu Khalil, Charle Amoah, Fred Kock

Abosso Goldfields Limited has been optimizing the comminution circuit at the Damang Mine Operation for the treatment of 100% primary ore. The optimization process started at a base rate of 343 tph when treating primary crushed primary ore, and was increased to above 600 tph with partially crushed primary ore. Abosso Goldfields engaged Orway Mineral Consultants (OMC) to assist with the optimization process in 2009 and the two companies have been working together since, to further refine the process. Continuous improvement was achieved through crushing circuit modifications, changes in operating processes and grinding control system utilization. This paper discusses the improvements developed for the increase in milling capacity and improvements in final product size.

Jan 1, 2012

By H. Henao, F. Canales

The present work evaluated the use of copper ore flotation tails as flux in the process of smelting copper concentrates. For this purpose, experimental and simulated liquidus lines were obtained at different ratios of tail/flux. Experimental variables included temperature, partial pressure of oxygen and sulfur dioxide and the conditions of tridymite or spinel saturation. The results indicate the feasibility of replacing the flux by increasing the temperature of the smelting process by 20°C. Results of simulation using FactSage and HSC confirm that the required increase in temperature can be achieved by increasing the flow of concentrate, enrichment of oxygen or increasing the matte grade. INTRODUCTION In the pyro-metallurgical process of copper production, the smelting stage produces two liquid phases, a sulphide phase rich in copper and another composed mainly of oxides called slag. The slag phase is the product of oxidation of the iron contained in the flotation concentrate. The smelting process which is carried out at temperatures of 1250°C, require the addition of silica as a flux and the injection of air enriched in oxygen (Schlesinger 2011). Currently, one of the most important aspects of the mining industry is the minimization of costs, the optimization of the use of available resources and the reduction of environmental impact. Under this context, the use of flotation tails from as a flux in the copper smelting process has the potential of reduced production costs and generate an environmental benefit by reduce the disposal amount of this waste material Regarding the use of copper tails as flux in the copper smelting process, a thermodynamic simulation study using the FactSage software had been reported in the literature (Parra et al., 2011). The results indicated an increase of 35°C in the temperature the liquidus for the equilibrium matte/spinel and a subsequent requirement of energy in the process of approximately 350 [MJ/ton slag]. Given that the calculated viscosity remains in the same order of magnitude, the melting temperature is a more relevant parameter for the evaluation of the use of tailings as flux.

Jan 1, 2019

By Michael K. Watkeys, Charlesworth. E. GUY, Jacobus E. Potgieter, Anhaeusser. Carl R., Roger L. Gibson, Alexander F. M. Kisters

Abstract - Intrusive features of cupriferous noritoids from the deeply eroded Proterozoic granite-gneiss terrane of the Okiep Copper District in South Africa illustrate the emplacement of basic magmas into a mid- to lower-crustal environment. The small, easterly trending intermediate to basic intrusions of the so-called Koperberg Suite display a wide variety of geometries, occurrence and emplacement modes, including dike-, sill- and plug-like bodies. Coeval granulite-facies metamorphism, partial melting and ductile deformation of country rock gneisses during intrusion of the basic magmas led to emplacement and dilation processes of the intrusions which differ significantly from those described for dikes and sills at shallow crustal levels. Regional tectonic stresses are largely negligible due to very low differential stress (?1 - ?3) during deformation and intrusion, which permits emplacement at high angles to the principal compressive stress and which follows favorably inclined structural anisotropies. Dilation of the basic intrusions is largely determined by compositional differences of host rocks and occurs by thermal erosion, i.e., assimilation of wall rock gneisses. Low length-to-width ratios of basic to ultrabasic dikes and predominantly diaper -like outlines of mesocratic bodies are indicative of low viscosity contrasts between the mafic magmas and high-grade metamorphic host-rock gneisses. Buoyancy-controlled ascent of the basic to intermediate intrusions is expressed by a broad compositional zoning of basic bodies with respect to the granite-gneiss stratigraphy. Various intrusion modes within the stratigraphic column of the granite-gneiss sequence reflect a lithological and structural stratification of the seemingly homogeneous granite-gneiss terrane.

Jan 1, 1994

By H. Asgari, A. G. Odeshi, J. A. Szpunar

In the current research, the role of grain size on the texture formation and mechanical behavior of rolled AZ31B Mg alloy is investigated under shock loading conditions. The grain size of the original asrolled sample was 8 µm and different grain sizes, e.g. 25 and 46 µm, were produced by heat treatments at temperatures in the range of 400-500 °C. In order to evaluate the effect of grain size on the anisotropy of mechanical behavior, the samples were cut along the rolling direction (RD), transverse direction (TD) and normal direction (ND) and tested at strain rates of 900 and 1200 s-1 using Split Hopkinson Pressure Bar. Texture measurements showed that initial texture of the samples cut from the as-rolled sheet is a weak rtype texture. However, a stronger texture was observed for samples with large grains. After shock loading, a (00.2) basal texture developed in all samples and the intensity of the basal poles was higher in samples with coarser grains. This observation is corroborated by high twinning activity and possible activation of pyramidal <c+a> slip in coarse grained samples. Besides, the strength of basal texture increased with increase in the strain rate. Furthermore, the samples with larger grain size showed lower strength and higher ductility, and this was observed for all investigated strain rates.

Jan 1, 2014

By Solar D. Andrés

Several large open pit mines are facing the challenge to design and plan an underground transition to sustain the long term future of their operations. The desired underground method is Block Cave since its natural high productivity and low operating cost that could compete against the open pit cost to mine the final open pit pushbacks. It has been found at several operations where this transition is taking place that the pit limit at which transition is performed is rather deep. This aims to think that perhaps several transition projects have started late in the life of an operation producing an over stress in the transition project and reducing the flexibility in the design of the overall infrastructure and a substantial lost in the complete project NPV. Traditionally the approach to plan open pit underground transition consists of sequentially deciding the final pit using a Lerchs and Grossman type of optimization to find the overall maximum pit shell and then running block cave simulations to find the best footprint for the underground option. The research summarized in this paper is related to the development of an integer linear programming model that aims to compute simultaneously the maximum NPV of the combined option final limit open pit and block cave underground footprint. The model has been tested using two large block models representing two of the current operations in the process of transiting from open pit to underground operations. Finally, the integrated open pit underground transition model is going to be compared to the traditional sequential approach in order to define which method achieves the best NPV. The paper illustrates both case studies in depth.

Oct 1, 2009

By G. M. Ritcey, K. E. Haque, S. H. Lucas

"Laboratory-scale hydrochloric acid leach tests were conducted on an Elliot Lake uranium ore. Hydrochloric acid leaches without an oxidant or with molecular oxygen (i.e., air or pure oxygen gas) as an oxidant favoured uranium and radium extractions. Conditions for maximum uranium, thorium and radium extractions with hydrochloric acid in the presence of sodium chlorate were determined. The highest extractions of uranium (96%), thorium (81%) and radium (91%) were obtained using a mixture of 44.0 kg HCI and 2.5 kg NaCIOJ per tonne of ore at 75°C with 18 hours &apos; retention.Flowsheets for two-stage leaching are proposed. The residues obtained from the second-stage leach contain uranium (0.002%), thorium (0.006%) and radium (15 to 20 pCi/g). Tailings of this nature are considered suitable for mine backfill, and, if pyrite is removed, suitable for surfacedisposal.IntroductionThe nuclear energy industry forecasts an increasing demand for uranium. This increasing demand requires not only largescale mining and processing of conventional and complex uranium ores, but also leads to the consideration of new and nonconventional sources of uranium, e.g., black shales, phosphate rocks, granite, sea water and fossil-fuel ash.Sulphuric acid leaching is the most widely used process to extract uranium from the ore(l). The leach liquor is separated from the solids (tailings), purified, concentrated in various intermediate stages, and finally a semi-purified product, yellow cake (80-85070 U30 8) , is precipitated. The tailings, which constitute nearly 98% of the total bulk of most ores, are usually discarded in surface disposal areas.The Elliot Lake region of Ontario is one of the major uranium producing areas in Canada. The principal uranium minerals are brannerite and uraninite, present as microscopic grains in the matrix of quartz-pebble conglomerates. The average grade is between 0.10 and 0.15% UPs. Up to 6.5% pyrite is also present in the conglomerates. Because pyrite is less reactive toward sulphuric acid leaching, almost all the pyrite goes into the tailings and eventually into&apos; the disposal sites."

Jan 1, 1980

By R. F. Hochstein, A. J. Neale, B. C. Flintoff

"Process control technology holds very significant potential benefits for many mineral and coal processing plants. The impact can be expected in terms of performance improvements (e.g. increased throughput, better quality control, higher availability), through reduced operating costs (e.g. lower reagent consumptions, manpower reductions) and in the form of intangibles (e.g. reduced vulnerability to manpower turnover, increased productivity in the user group). However, the installation of a process control system will represent considerable capital expenditure and will generate an operating cost. No management team would approve the funding for such a project without some reasonable measure(s) of the profitability of a proposed system. This paper describes a methodology for addressing the justification problem. Of particular interest is the approach to quantifying performance improvements, frequently found to be the predominant benefit of process control.INTROPUCTIONProcess control has become widely recognized as an essential component of any processing operation. It has direct impact on productivity, process efficiency and product marketability. The reported pay backs associated with successful installations underscore this observation. As a consequence, many operators who have little in the way of process automation are looking to initiate control projects, while those who currently enjoy some level of automation are looking to upgrade existing control systems (= process + instrumentation + hardware + software + operators + support). While the emphasis here would appear to be on retrofit process control projects, new plants, or those currently in the design stage, will usually find themselves in one of these categories shortly after startup 1."

Jan 1, 1990

By Gordon Thompson

"Development of the unique Mine Games exhibition at Science World British Columbia is the largest ever collaboration of many interests to present the story of mining and the issues of mineral development delivered to the public by a science education centre.IntroductionMineral education programs have long been a major focus of the British Columbia mining community. Mine Games and its tremendous potential to enhance industries image and the public&apos;s awareness of mining is unequalled in the field of Issue Based Education Exhibits.The main goal of the exhibition is to look at the future of resource industries in a rapidly changing world of economic activities, new technologies, and growing public concern for the environment. Three challenges were the aim of the exhibition: to increase participation, to serve as a tool to increase interest in science and technology, and to draw an increasing number of school students to the interests of geology and the earth sciences. Mine Games is to serve as a meeting place for discussion of issues and where reliable information can be shared and new ideas explored.The exhibition is designed to develop new approaches to hands on learning that encourages visitors to explore and generate discussion and thinking with respect to resource development activities.The role of author, beginning in 1993, was, with senior industry leaders, to coordinate the raising of $1.3 million to complete the funding of the $1.6 million project total. The second and most interesting challenge was to work with the many minds that were collaborating to create the exhibition and to assure that the facts and science were correct. This involved the coordination of ""expert groups"" that verified the science and technology and the issues that the creative design team at Science World planned to use in development of each exhibit module."

Jan 1, 1995

By N. R. Andrade-Gonzalez

In this paper, the effect of magnesium and strontium additions on the heat treatment behaviour of cast A319,2 alloy was investigated, Permanent mold samples were heat treated at 495 °C for 4 and 24 h, then quenched in hot water and aged at 180 °C and 220 °C for different temperatures, It is found that multiple aging peaks are present in the age-hardening curves of Al-Si-Cu alloys, mainly when Mg and Mg-Sr are added, The results of electron probe microanalysis (EPMA) observations reveal that the age-hardening behaviour is related to the precipitation sequence of alloys, For the Al-Si-Cu alloy, the first aging peak is the result of the high-density GP zones, while the subsequent peaks arise from metastable phases, Obvious intervals during the transition from GP zones to metastable phases may be the main reason of the formation of multiple aging peaks, It is seen that addition of Mg (-0,40 wt %) leads to the precipitation of coarse Al5Mg8SioCu2 particles. When modifying the high Mg alloys, Cu-intermetallics segregate in areas away from the growing Al-Si eutectic regions, Modification with strontium retards the precipitation of the silicon out of the matrix.

Jan 1, 2005

By Zoltan Hajnal

Magnetic studies have been carried out on 88 surface and 157 underground samples from the Coronation Mine area of northern Saskatchewan. The intensity of the surface samples was compared to trace element determinations from the same locality. A good correlation was found between the titaniferous constituent of the rocks and the intensity of magnetization. From the direction of the remanent magnetism, two virtual geomagnetic poles were determined -latitude 12° 54&apos; North, longitude 158" 17&apos; West; and latitude 23" 42&apos; North, longitude 163° 45&apos; West. The sulphide ore specimens showed anisotropic susceptibility characteristics. A relationship was found between the measured maximum susceptibility values of the ore specimens and the direction of the tectonic forces which are considered to have formed the structure at the Coronation mine. Introduction T HIS paper summarizes the results of a study of the magnetic properties of samples from well-known Precambrian formations. The observed data give information for an interpretation of the magnetic field conditions in Precambrian times. The high magnetic intensity values indicate the importance of the study

Jan 1, 1965

By Robin N. Adair

The Halfmile Lake stratiform volcanogenic massive-sulfide deposit consists of pyrrhotiterich breccia-matrix sulfides and pyrite-pyrrhotite-rich layered sulfides that form a laterally continuous sheet stratigraphically underlain by an extensive pyrrhotite-chalcopyrite-quartz stringer zone. Mineralization is hosted by a sequence of felsic pyroclastics and volcanic-derived, fine-grained metasediments. The proportion of volcanic to sedimentary rocks indicates increasing vent proximity from southwest to northeast across the deposit area. Fine- to medium-grained felsic pyroclastics and roughly equal amounts of fine-grained metasediments comprise the stratigraphic footwall to the mineralization. Quartz-feldspar porphyritic bodies cut this sequence and may have provided the heat source for exhalite activity. Felsic tuffs, locally crystal-rich, and lesser amounts of metasedimentary rocks make up the immediate stratigraphic hanging wall. This sequence is stratigraphically overlain and locally interfmgered with mafic volcanics that contain substantial proportions of felsic fragments. Deposition of sulfides post-dated the beginning of felsic volcanism, which places the deposit in the middle of the Lower Tetagouche Group. Compositions of the volcanic rocks range from basalt to rhyolite and exhibit sub-alkaline affinities. Strongly overprinted whole-rock, trace-element, and REE geochemical signatures resulting from mineralizing hydrothermal activity confirm the genetic relationship between the stringer zone and the mineralized sheet. Large-scale D1 folding has overturned the entire sequence. D1 thrust faults and related sheath-like folds have profoundly affected sulfide distribution. D2 is manifested by a penetrative S2 foliation, and D3 is represented by large-scale open folds.

Jan 1, 1992

By L. Betteridge, A. Marks

"An OK 300 cu. ft. Skim - Air cell was installed at the HBM&S concentrator in Flin Flon in 1987. Since that time, 3 additional OK Skim - Air cells have been installed in HBM&S concentrators. The cell treats a coarse 70% solids slurry with a residence time of 2.5 minutes. The product from the cell (a unit cell type application) is a final grade copper concentrate with high precious metal values. Since its installation, the cell has improved gold recovery by 10 - 15%. Process variables such as circulating load, pH, froth depth, feed size, and reagent additions all have an effect on the operation of the cell. Maintenance on the cell has been minimal. Initial operating problems involving level control have been significantly reduced and operations are now relatively trouble free. Although very successful at Flin Flon, site specific operating circumstances will determine the suitability of this cell. INTRODUCTIONHudson Bay Mining and Smelting operates four concentrators in Northern Manitoba. Three treat copper-zinc ores, the fourth mills a copper-nickel ore. The Flin Flan concentrator operates two circuits in parallel which treat copper and zinc ores from the Trout Lake and Callinan mines. Both circuits in the Flin Flan mill have Skim-Air cells integrated into the grinding circuits.The Trout Lake cell was installed first and had a payback period of a few months. Required modifications to the cell were made to enhance its performance. These included changing the discharge valve size, tuning the level controller, and installing an insert into the rubber valve sleeve to increase its wear life. The payback period on the Callinan cell was significantly reduced because these modifications were completed prior to its installation.The cells produce a final grade copper concentrate and since their installation gold and silver recoveries to the final copper concentrate have increased significantly. Operating parameters such as coarseness of cell feed dictate the metal recoveries and froth depth determines the selectivity of the cell and therefore the grade of the concentrate.The Skim-Air cell can be suitable in applications where a final product is generated. However, when a bulk concentrate, which requires further separation, is produced, the coarseness of the product may not make it amenable to conventional flotation.The Flin Flan mills Skim-Air cells have worked exceptionally well with little maintenance required."

Jan 1, 1991