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By R. J. Twigg, S. D. Chang

"The production of heavy water, the moderator in a CANDU reactor, is examined following a flow sheet of a typical Canadian plant. The process involves the extraction and concentration of deuterium from natural water through a chemical exchange mechanism with hydrogen sulphide. Consequently, corrosion problems associated with sour environments – the use of hydrogen sulphide - are an everyday problem and have led to the development of a highly refined materials selection and testing program to prevent equipment from failing prematurely.IntroductionHeavy water is a naturally occurring compound in ordinary water and is formed from the combination of two deuterium atoms and one atom of oxygen. Deuterium is a heavy hydrogen atom which has a nucleus of on e proton and one neutron. Hence, heavy water is a combination of heavy hydrogen and oxygen and is chemically known as deuterium oxide. It looks and tastes like ordinary water but it freezes at 3.8°C and boils at 101.4°C. The molecular weight of heavy water is 20 as compared to 18 for ordinary water; the density of heavy water is ten per cent greater than that of ordinary water.Although heavy water and ordinary water exhibit only small differences in their chemical and physical properties, there are large differences in their nuclear properties, the most important of which is the neutron moderating ratio, used to measure the ratio o f the slowing down power to the neutron capture characteristics. For heavy water the ratio is 21000 and for ordinary water it is 50. This high moderating ratio is essential for achieving a high neutron economy. Heavy water is, therefore, chosen as the moderating and heat transport fluid in the CANDU reactor."

Jan 1, 1983

By John H. Schloen

"The object of this paper is to review electrolytic copper refining as it was in 1954(1), as it is now in 1984, and to comment on the many improvements which have been made in the last thirty years.In 1954, and even in 1984, the ASTM specification B 115 for cathode copper was 99.90% minimum copper plus silver content and 100% minimum electrical conductivity, IACS standard. However, to meet competition and to satisfy the requirements of the fabricators and the electrical industry, the electrolytic refinery must supply a product of 99.95% to 99.96% minimum copper content, and 101fJlo minimum electrical conductivity.The range of cathode impurities reported by 20 major copper refineries in 1954 are given in Table I.The much more rigid British Specification, DD 78, for high-purity cathode copper, specifies individual elements, as well as groups of elements, as shown in Table 2.The Svenska test has been replaced by a similar procedure which uses 2.r mm diameter wire. The ISO test is the one listed in the DD 78 specification. In Table 3, corresponding values for the Svenska and ISO test s are given for various wire bar coppers."

Jan 1, 1986

By S. Borle

The microstructural features produced in friction stir welded AZ31, AZ80 and AZ91 alloys are examined when different welding parameters are applied. The microstructures primarily consist of a-Mg grains with a-Mg + Mg17A112 colonies, however melted films of Mg17A112 are produced in AZ91 alloy when high rotation speeds are applied. When the rotation speeds are slow, or the travel speeds are fast the Mg17A112 were incorporated into the stir zone, however they do not exhibit an elongated lamellar morphology associated with melted films. In the case of AZ80, the extruded base material contains a smaller fraction of Mg17A112 and few of these phases are observed in the stir zones. The results are explained based on the dissolution rate and melting temperatures of Mg17A112 controlling the overall morophology and fraction of phases in the stir zone.

Jan 1, 2011

By J. F. Hazzard, R. J. Chalaturnyk, C. Khazaei

"Various measurement, monitoring and verification (MMV) techniques are used to ensure the safety of operations in petroleum projects. One of these techniques is microseismic (MS) monitoring of the caprock. A challenge in MS monitoring of caprock is that unlike projects such as tunnelling in hard rocks, the number of recorded events are much smaller and also wide spread through the rock mass which makes interpretation of the physical meaning behind the events very difficult.In this paper, a numerical technique is introduced and validated for coupling a finite difference code, FLAC3D (Fast Lagrangian Analysis of Continua), with a discrete element code, PFC3D (Particle Flow Code). Then, a similar approach is adopted for modeling microseismic events in the caprock. For this purpose, the underburden, reservoir and overburden layers are modeled by FLAC3D. A rather small section of caprock above the reservoir is nulled in the FLAC3D model and substituted by a PFC3D inclusion. The reservoir pressures are then applied to the reservoir section of FLAC3D. Once the FLAC3D cycles, there will be induced pressures in the caprock due to its undrained response to the change in pressures within the reservoir. These induced pressures are transferred to PFC3D as boundary velocities. Then the PFC3D cycles and sends back the boundary forces to FLAC3D. This back and forth process continues until equilibrium is reached. During this process, there will be bond breakages within the PFC3D inclusion that can be regarded as MS events. An algorithm for recording the microseismic energies based on a change in local strains is also implemented. The results are then compared with real data. The effect of injection fluid temperature is also studied. No significant appearance of microseismic events was observed due to injection of CO2 in both cases (i.e. with or without considering temperature). However, this continuum/discontinuum approach seems promising for understanding the microseismic response of caprock in more detail and also using the MS data for validation of geomechanical models."

Jan 1, 2015

By A. G. Roach

IT IS generally stated that the gold ores of Nova Scotia are free-milling, and for the most part this is true. However, there is a certain proportion of the gold finely disseminated throughout the sulphides, notably arsenopyrite, and this gold is definitely not recoverable as 'free-milling' gold by amalgamation. The proportion of free-milling gold to total gold seems to vary widely in different localities in the Province and is lowest in deposits of the fissure-vein type. The problem of recovery of these relatively recalcitrant values is usually one of economics, in some plac.es a simple gravity concentrate being of such low tenor that its extraction and subsequent disposal will not bear the costs involved. In other cases, such a high percentage of values escapes from the mortars and plates that concentration is definitely indicated. The size of the mining operation is also an important factor. In the large majority of cases, however, some concentrating step is warranted, even if the resulting concentrate is stock-piled until sufficient has accumulated to justify further treatment.

Jan 1, 1940

By H. Dundar

The first application of High Pressure Grinding Rolls was in 1985 at a cement plant, for the purpose of capacity improvement. Then various circuit configurations were derived to achieve a reduction in overall specific energy consumption, by transferring more of the grinding required to the HPGR. In most circuit configurations, the recycle of fines is required for effective breakage between the rollers. By increasing the fines amount in the feed material to a specific level within the recycling load, a uniform material bed is created and a higher pressure gradient along the roller width is obtained, resulting in compact flakes, including more fines. The fines recycle results in enhancement of the interparticle breakage. This paper will discuss the effect of the feed size distribution on HPGR performance.

Jan 1, 2012

By G. P. Gu

The in-service 90/10 cupro-nickel tubes in a water-chiller system suffered from severe corrosion damage during their relatively short service life causing unexpected down time. In addition to downtime, the environmental risk associated with losing refrigerant was also a concern that initiated this investigation, Microstructural investigation using SEM and electron microprobe indicated that pitting corrosion had resulted in local nickel depletion, During the corrosion process, copper appeared to have re-deposited around the corrosion pits accelerating the local corrosion.

Jan 1, 2005

By J. G. Speight

Laboratory studies indicate that autogenous heating of low-rank coal can be prevented by a prior treatment which involves immersing the coal for short (5-15 min.) periods in an inert liquid at temperatures between ~ 350° and 400°C. Such "carbonization" effectively reduces the accessible pore volume of the coal to levels at which heat generation through subsequent sorption of moisture and oxygen is too slow to cause significant temperature rises in a stockpile. In addition, this treatment also irreversibly removes most of the moisture held in the raw coal and raises its calorific value by as much as 10-12%.

Jan 1, 1973

By Lin Li, Ahmad Ghahremaninezhad

"In this paper, the electrochemical behavior of ferric and ferrous couple on the pyrite surface was studied by application of the chronoamperometry technique in an acidic solution at room temperatures and atmospheric pressure. The effects of the pyrite origin, ferric and ferrous ions concentration on the electron transfer kinetics of Fe3+/Fe2+ reaction were probed. Tafel behavior of all the test conditions were developed. The results showed that the ferric-ferrous reaction on pyrite electrodes with different origins have a common mechanism, despite different reaction kinetics. The exchange current densities of the redox reaction have the same magnitude of about 10-5 A·cm-2, which is far lower than the value reported for the gold and platinum electrodes, but larger than that of the chalcopyrite electrode. The cathodic transfer coefficients are between 0.4 and 0.5, while the anodic transfer coefficients appear unusual with the lowest value being 0.23. It was also demonstrated that an increase of one order of magnitude of iron concentration has no clear effect on the exchange current density and cathodic transfer coefficients of Fe3+/Fe2+ redox reaction.INTRODUCTIONPyrite, FeS2, is mostly considered as a gangue mineral which frequently coexists with valuable minerals and metals, such as gold, copper and nickel. Its separation from valuable minerals can be a costly process (Chandra & Gerson, 2010). In refractory gold ores, the fine gold particles are locked inside the pyrite structure. Oxidative leaching of pyrite is a hydrometallurgical method to destroy the structure of pyrite and expose the fine gold particles to the cyanide solution in the downstream cyanidation circuit. Pyrite oxidative leaching can be achieved by oxidation of pyrite via oxygen and ferric ion(McKibben & Barnes, 1986). In fact, pyrite oxidation by oxygen and ferric is a significant source of acid mine drainage(AMD), which adversely causes serious environmental problems(V. P. Evangelou, 1995).The pyrite oxidation mechanism is accomplished in three consecutive steps: (i) pyrite is oxidized by oxygen and ferrous ion formation (Eq. 1); (ii) ferrous oxidation by oxygen and ferric ion formation (Eq. 2); (iii) pyrite oxidation by means of ferric ions (Eq. 3). Hence, both oxygen and ferric participate in the pyrite oxidation process (Moses & Herman, 1991):"

Jan 1, 2016

By L. C. Bird, A. I. A. Salama, M. W. Mikhail

"A program of sampling in Canadian washeries was carried out by the Coal Research Laboratory (CRL) over a period of two years to evaluate the performance of various density separators in these operations(1). Operating data on quality and recovery of products, separation efficiencies and cutpoints for each separator type are compared with data predicted using computer models developed from previously existing data.The Heavy Medium Cyclone (HMC), Heavy Medium Bath (HMB) and jig models give predictions of recoveries and qualities of products for sizes coarser than 10mm with absolute value of error mean less than 7 per cent, whereas predictions of the Water Only Cyclone (WOC) model for -10mmfine coal are with absolute value of error mean less than 8 per cent. Although less accurate for -10 mm fine coal, the HMC and jig models produce predictions of recoveries with absolute value of error mean less than 2 per cent and quality of products predictions with absolute value of error mean less than 28per cent which are generally acceptable because more liberation in the fine fractions appears to compensate for any difference in the accuracy of separation, resulting in good prediction of the clean product. However, ash content of the actual fine refuse was lower than predicted. The difference is attributed to the highly friable nature of Canadian coals which tends to cause an excessive loss of coal fines to the fine refuse.A comparison study based on quality and recovery of products is made between the Dutch State Mines (DSM) models and the recently modified models, both produced comparable predictions."

Jan 1, 1985

By D. E. M. Plaumann

"The wet grinding of asbestos has attracted the attention of engineers for many years as a means of improving fibre liberation from the ore. Today, added impetus for wet grinding has resulted from a need to minimize worker exposure to asbestos dust in conventional dry mills using air, as well as a need to provide a cleaner, technically superior fibre for use by product manufacturers. However , high viscosities of asbestos slurries create transport and grinding difficulties which have been a factor impeding use of a wet grinding process.Laboratory evaluation of reagents to reduce viscosities of asbestos slurries found that one reagent, XFS-4272.00, reduced the viscosity of a 35% (by weight) slurry by 75%. The impact of XFS-4272.00 on actual grinding parameters were evaluated using a pilot plant rod mill. Slurries containing 78% solids and XFS-4272.00 were successfully milled and asbestos fibres from that milling compared favourably in liberation and relative surface area to asbestos fibres obtained from milling a 4% slurry without additives.IntroductionAlthough the use of asbestos has been declining over the last few years, the large deposits of chrysotile in eastern Canada (Quebec in particular) remain very important. Asbestos production in Canada stands ninth in volume for mineral production with over 740 000 tonnes produced in 1985. Of this quantity, 722000 tonnes were exported with a value of $446 million . Canada is second in world production of asbestos behind the U.S.S.R ."

Jan 1, 1988

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 André Bérubé

"IntroductionSince the disappearance of Les Forges du Saint-Maurice at the end of the last century, many historians have taken an interest in the lengthy past of this enterprise. They considered the political, socio-economic, administrative and anecdotal aspects of the industry, but barely dealt with the elements of technology. The purpose of this article is to try to fill this gapru.Les Forges du Saint-Maurice was an integrated industrial concern, specializing in the production of semi-finished wrought iron and finished cast iron, that operated almost without interruption between 1734 and 1883. Les Forges first came into being in 1729, when Montreal merchant Francois Poulin de Francheville submitted to the king of France a request for the right to exploit the bog iron ore deposits on his seigneury of Saint-Maurice. This request, agreed to in 1730, was one of a long series of attempts, previously unsuccessful, to establish a local iron industry in the colony. Several such proposals were held up by a lack of capital from promoters or a too rigid application of the mercantilist policy by the metropolis. In 1730, however, the French minister Maurepas favoured a more liberal policy which would encourage private enterprise. The benefits of an iron industry to the naval construction industry was a factor that caught the attention of administrators. The choice of the site for Les Forges was based on the following factors:• the abundance of surface deposits of bog iron ore in the Saint-Maurice region;• the presence of a vast supply of hardwood and conifers needed in large quantities by this industry;• the proximity of sandstone and limestone deposits, indispensable materials for the construction and operation of the blast furnace;• the presence of a water stream, with sufficient flow to provide the hydraulic power needed for the operation of the machinery."

Jan 1, 1983

By P. MacPhail, G. S. Dobby, I. M. Flint

"The objective of the laboratory work described in this paper has been to develop a method f or producing small gas bubbles at moderate to high gas rates in a flotation column. Small bubbles are particularly important for attaining reasonable flotation rates of fine particles. An ultrasonic aerosol generator has been employed to add frother solution directly to the gas stream. Using porous glass and filter cloth spargers, aerosol frother addition has produced bubbles at 1/2 to 2/3 the diameter of those produced by conventional frother addition to the liquid, at a lower frother consumption.IntroductionGas bubbles are generated in a flotation column most commonly by forcing gas through a porous medium called a sparger. Typical sparger material includes rubber (pierced with small holes) , fabric (such as filter cloth), fritted glass, or porous metal (steel or bronze) . Solid sparger material is suitable for laboratory use; however, for industrial applications a flexible sparger such as rubber or fabric is necessary to prevent the eventual plugging of orfices with solid particles and/ or precipitates. An exception to this is the use of a gas liquid contactor external to the column in combination with pressure release of gas in water, a method that has been demonstrated to produce very small gas bubbles. The typical objective of bubble generation for flotation column purposes is to produce bubbles with diameter of about 0.1 cm (and less) at a gas superficial velocity of 1 cm/s to 3 cm/s. In general, the smaller the bubble, the better. In man y cases, though, there is little , or nothing, gained by generating bubbles less than about 0.05 ern in diameter.Several factors affect bubble size when generated by a sparger: gas rate, orifice diameter, sparger surface area, surfactant type, surfactant dosage, and static head. At very low gas rates bubble diameter is independent of flow rate and is proportional to orifice diameter. At the moderate gas rates encountered in flotation columns bubble diameter, db' is related to gas flow by: db oc vg n, where vg is superficial gas velocity (rate of gas flow per unit column area). For porous steel and filter cloth, n has a value of about 0.25 for vg between 0.2 cm/s and 2 cm/s(2). The magnitude of the effect of orifice diameter at these gas rates is unclear. The effects of frother type and concentration on bubble size issuing from a single orifice have been measur ed by Miagkovaru , shown here in Figure I(IS). The reduction in bubble diameter upon surfactant addition is due to the lowering of interfacial tension created by adsorption of surfactant at the gas liquid interface."

Jan 1, 1988

By K. Bunney, R. Pleysier

The deportment of a suite of elements through representative gold ore processing unit operations in cyanidation has been investigated. Chromium and lead are not soluble in alkaline cyanide solutions. Arsenic, antimony, cobalt, molybdenum, selenium, tellurium and vanadium are soluble, but typically do not adsorb onto activated carbon to any appreciable extent. Silver, copper, cadmium, mercury, nickel and zinc to varying extents report along with the gold to the carbon eluate. Cadmium, mercury and zinc can report to the carbon regeneration kiln off-gases. Strontium is soluble and adsorbs on carbon where it remgins.

Jan 1, 2011

By G. R. Baiden

"An Automatic Haulage Truck (AHT) has been developed for manless tramming of run-of-mine material in an operating mine. The AHT has a 70-ton capacity and uses an electric trolley system in combination with a computer control system to operate the vehicle. The purpose of the AHT was to provide a high capacity, high productivity material transfer system where conveyor belt applications are not immediately practical.The AHT project was started in 1983 at Inco Limited, Ontario Division as a result of the need for rapid material transport to match increased extraction rates resulting from bulk mining methods. The original concept was to use a continuous loader with the truck. However, in order to minimize development problems the truck project was considered a stand-alone project.The AHT project consisted of concept development, preliminaryand detailed design, manufacture, surf ace testing and mine implementation.The AHT was manufactured and ready for testing in 1988. At this point the truck was first moved onto the test track for debugging. This proved successful and in 1989the decision was made to install the AHT at Little Stobie mine on 2000 level. Commissioning of the system was started in 1990and at present a fully functional automated haulage system is in place at Little Stobie mine producing 3000 tons/day.This paper describes the project presenting results achieved to date."

Jan 1, 1992

By L. A. Wolff

"Second only to profitability (but not always), productivity is the most sought after measurement for any operation. Whether it is in mining, manufacturing, construction, etc. managers always strive to know how productive various plants are. Even the Federal Government publishes, on a monthly basis, the nation's factory productivity.Just what is productivity and how is it measured? This is an important topic that needs definition. There could be as many definitions as there are people who use it. In the mining industry, the problems of defining productivity would be analogous to the definition of equipment availability. Each mine uses its own definition to suit its needs. Webster's Dictionary primary definition for productivity is ""the quality or state of being productive,"" with productive defined as ""yielding or furnishing results"". This is a definition open to a broad spectrum of interpretation. A discussion of how productivity is currently used in the mining industry and an introduction to a potentially different approach to its measurement and meaning is outlined in this paper.Defining ProductivityTypically, mining companies track several productivity measurements. These are partial measurements and can include the following: tons per specific equipment class per hour, tons per man-hour, and tons per shift. None of these, however, track the over -all performance of an operation, that is, a unit of output per unit of input.For a mining operation, output can be defined as the ore for mill processing. Input includes the required components of production to get to the first step of processing.The Wesbter's Dictionary definition exposes a major fault with the popular conception of productivity. The critical issue of accountability is not addressed. Anyone can produce, but how effectively and efficiently are resources used? Quantifying an inclusive measurement is difficult. Statistics referring to an increase in productivity are often published. For example, the statement, ""gold productivity has increased by 10%"" has many potentially dangerous interpretations. One must ask, what does this statistic really mean? Did gold companies produce 10%” more gold? Were less manpower or equipment required to produce an equivalent amount of gold? Did ore grades increase resulting in more ounces of gold produced, etc. Obviously, production and productivity can have similar implied applications and meanings, but also two different, distinct meanings.To mitigate a problem like this, a standard needs to be developed within the mining industry. Because of varying ore grade, changing waste to ore ratios, different mining methods, etc. all of which have a direct impact on mining, development of a standard is difficult. Kendrick(1) discusses the use of Total Factor Productivity as a productivity measurement. Summarized, the total factor productivity measure is an indication of the change in efficiency in the use of basic labour and capital factors associated with an operation.This measurement has little meaning when calculated at a given point in time. It should be an on-going calculation, tracking an operation over a period of time, to evaluate trends. These trends can be used to determine if an operation's productivity is what it should be, and alert management to potential problems before they become major and adversely affect an operation."

Jan 1, 1990

By N. Morrison, E. J. Rogans, A. J. Macintosh, N. Schoeman

"The design of carbon-in-pulp (CIP), and carbon-in-leach (CIL) adsorption circuits has essentially remained unchanged since the early days of the carbon process for gold recovery. For CIP circuit the pulp residence time is traditionally fixed at one hour per contactor with a carbon concentration of between 15 and 20 grams per litre, and the counter current carbon transfer rates are in the region of 15% pulp recycle. For CIL, the pulp residence time is usually three hours per contact or, with lower carbon concentrations ( 5 to 10 grams per litre).The drawbacks of using the counter current CIP/CIL adsorption circuits are discussed using modeling developed for CIP/CIL plant design. Counter current CIP/CIL, circuits are then compared with the carousel method of adsorption circuit design.The use of equipment suitable for the carousel approach is discussed which is, the AAC cylindrical and pumping (MPS) screens, the AAC pump-cell plant and launder designs.Finally, two plants at the Vaal Reefs Gold Mining and Exploration Company that use carousel adsorption circuits, namely the Vaal Reefs No. 1 Gold Plant, a CIL plant with stepped contactors, and the Vaal Reefs No. 2 Gold Plant, a CIP using a very short residence time (AAC pump-cell) are discussed."

Jan 1, 1998

By Stephen Mcgibbon, Tim Twomey

"Abstract - The High-grade Zone (HGZ) was discovered 5000 ft (1520 m) below surface in the hangingwall of the existing orebody, 46 years after the Red Lake mine first went into production. The very rich ore of the HGZ is characterized by a remarkably abundant distribution of visible native gold. The location of this discovery challenged conventional wisdom at the time and its genesis has yet to be fully understood. Textural observations of ore within carbonate veins as well as crosscutting relationships suggest peak-metamorphic emplacement for at least some of the gold. Post-lamprophyre dike remobilization of gold is locally observed in the HGZ. Structure and dilatancy were the key elements for localizing ore at the Red Lake mine. Ore occurs where a fault trend intersected folded ultramafic volcanic rock that created a semi-permeable cap-rock to ore fluids ascending the "feeder" structure. This was enhanced by strong competency contrasts between the eastern ultramafic rocks, felsic volcanic rocks west of the HGZ, and the mafic volcanic host to ore - an exceptional environment for the development of protracted dilatant fluid pathways for gold deposition.Development in the HGZ began in February 2000 and reached commercial production on January 1, 2001 at a capital cost of US $53 million. December 2001 reserves are 1.9 million short tons (1.73 Mt) at an average cut and diluted grade of 2.05 ounces per ton gold (70.5 g/t) containing 3.8 million ounces of gold. The extremely rich ore presented a unique challenge in grade estimation for the Geology Department at the mine. The historic cutting factor was replaced by a statistical method as more data were collected from mining and mill reconciliation. The mine produced 503 000 ounces of gold in 2001. Exploration at the mine is targeting HGZ-type ore formation within basalts associated with the intersections of fluid pathways and folded ultramafic rocks, as well as other targets."

Jan 1, 2001

By S. H. Lucas

"This paper describes the development and application of single-stage fluidized bed continuous ion exchange to the following processes: removal of base metals from mine water; cyanide removal from gold mill waste; uranium removal from sulphuric acid leach liquor; and uranium removal from mine water. IntroductionThe recovery of metals by fixed bed ion exchange has been practiced for many years. However, the operation has been semi-continuous and can only treat clarified liquors. Substantial savings could be made if the operation were continuous, thus reducing the resin inventory, and if the costly filtration and clarification steps could be eliminated. Work has been in progress over the past twenty-five years on the recovery of metals from unfiltered ore leach slurries, heap leach liquors and mine drainage waters containing a small amount of suspended solids. In the case of dilute waste solutions, with suspended matter and high flow rates, filtration is usually prohibitively expensive.Continuous ion exchange operation using fluidized beds has made it possible to reduce considerably the resin inventory and to allow the treatment of unclarified liquors and slurries. The subject has been reviewed on several occasions (1. 2. 3, 4). Although fluidized beds in multi-stage columns are an improvement over previous resin-in-pulp treatment, they have complicated internal structure and I or involved automatic control systems to move the resin stages.Slater and Prud'homme performed studies on multi-stage fluid beds, and concluded that the performance of single, deep fluidized beds of resin with continuous or semi-continuous flow of both phases would be worth investigating, particularly in the case of very dilute metal solutionsoi, A pilot plant was designed and built at CANMET in a cooperative project with Dr. Slateroi. The use of deep fluidized beds of resin (with a large height/diameter ratio) for treating dilute solutions has the attraction of engineering simplicity. Extreme simplicity of equipment design is considered of paramount importance when treating, for example, mine waters at high flow rates, possibly of the order of several million gallons per day. This paper describes the development of the concept of single-stage fluidized bed continuous ion exchange arid reviews the pilotplant development of processes for the treatment of base metal mine water, cyanide waste water, uranium leach liquor and uranium mine water."

Jan 1, 1980