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By David R. Lentz

At True Hill in southwestern New Brunswick, low-grade porphyry-style Bi-8n-Mo greisen mineralization is associated with the cupola of an epizonal granite porphyry (granite) that also exhibits three episodes of brecciation. The first episode of brecciation is an in situ, 8 m to 10 m wide transitional zone of net-veined to coarse-grained "blocky" endogranitic mesobreccia that is chloritized and greisenized and hosts weak disseminated minerali.zation. In a zone closer to the host rockgranite contact, angular fine- to coarse-grained endogranitic mesobreccia with greisenized matrix is superimposed on the earlier transitional breccia. The latest episode is fault-controlled and consists of quartz- and chalcedony-hosted sub-angular to rounded fine-grained "pebble" mesobreccias that crosscut and brecciate the other breccia types, as well as the adjacent altered metasedimentary country rocks. The first two episodes of brecciation are magmatic-hydrothermal in origin related to hydrofracturing of the granite carapace and are accompanied by greisenization and mineralization, whereas the post-mineralization, silica-hosted, "pebble" mesobreccias related to hydromagmatic, low-temperature fluid circulation and/or boiling along faults near the contact. These magrnatichydrothermal and hydromagrnatic mesobreccias are similar to those associated with W-Mo-Bi porphyry-greisen mineralization at the Mount Pleasant deposit.

Jan 1, 1994

By Emmanuel Henry

The Kiruna Mine, operated by Luossavaara-Kiirunavaara AB (LKAB), is a large-scale sublevel caving operation located in Arctic Sweden. Iron ore is extracted at a rate of 60 000 tpd from a four-kilometre long, 80-100 m thick and 60-degree dipping orebody. Actual production depth is 800 m under the top of the footwall and about 550 m under the average regional ground level. Because no support is left between the footwall and the hanging wall and despite the relatively low mining depth, extraction results in the formation of a huge stress shield modifying the original stress field and concentrating it just beneath the mining level. Effects of stress concentration on the rock mass are monitored through field observations and a seismic system. Severe stress-induced deterioration of openings is visible to a certain radial distance from the mining level: pillar crushing and fault slips are more and more common and extended. The seismic system, installed in collaboration with CANMET, confirms the field observations and completes them in the rock mass: fault slips and major seismic events are recorded. The system proves its effectiveness to outline the extension of the dynamic response of the rock mass, which actually seems much larger than field observations let think.

May 1, 2001

By M. Bourassa, R. del Villar, S. St. Arnaud, J. Valenzuela

"Autogenous grinding is used quite frequently for mineral comminution as a result of its lower capital and operating costs. However, it is more difficult to control than conventional grinding, particularly when the autogenous or semiautogenous mill is the only comminution stage (i.e. no secondary grinding is available). Analysis of the control strategy used then becomes extremely important, a task that is greatly simplified by the use of an empirical dynamic simulator:This paper presents the methodology used in the development and the calibration of such a simulator for the autogenous grinding circuit of an iron are concentrator: The various steps are described: industrial data acquisition, preliminary treatment of the gathered information. and empirical modelling of the process. Finally, both the actual and the proposed control strategies are compared using simulation results.This exercise has shown that the variability of some of the controlled variables could be reduced through a better handling of the water addition and the use of filters on some of the signals used for control purposes. The reduction in variability of critical variables, such as power draw, would allow their average value to be increased without the risk of exceeding their safety values. Some advanced control techniques were also tested, with interesting results."

Jan 1, 1995

By P. E. Weidmark

"Energy, Mines and Resources Canada has published the first in a new series of reports that will examine selected mineral products that are imported.""Vanadium - An Imported Mineral Commodity"" looks at one of the 32 raw materials for which Canada currently is totally dependent on foreign sources of supply. Vanadium is used in Canada mainly as an alloying element in the manufacture of high-strength, low-alloy (HSLA) steels.The series will examine the supply systems for various selected imported non-fuel minerals, as an aid to developing policies that might lead to reduced dependence on external sources. Each report in the series will address a numberof questions:What countries do the mineral and its principal sub-products come from?How do they get to Canada?What are they used for?How vulnerable is the supply chain to disruption?Are there alternative sources?Are substitute materials available?In summary - how serious is Canada's supply problem for the mineral in question, and what should be done about it?Mineral Bulletin MR 188, ""Vanadium - An Imported Mineral Commodity"", is available for $3.00 ($3.60 outside Canada) from authorized government bookstore agents and many other bookstores, or by mail from the Canadian Government Publishing Centre, Hull, Quebec, KIA OS9."

Jan 1, 1981

By J. C. Johnson

Underhand mining with cemented mill tailings for backfill has proven to be a safe and effective alternative to conventional overhand mining for rockburst prone mines. The ability of the cemented sandfill to survive a rockburst shock wave without failing has been observed at mines in the Coeur d?Alene Mining District many times in the last twenty years. To better understand the dynamic loading of this commonly used support material the National Institute for Occupational Safety and Health (NIOSH) performed laboratory experiments using a split Hopkinson Pressure Bar (SHPB) to quantify the maximum stress and energy absorption of cemented mill tailings from the Galena mine. Cylindrically shaped cemented backfill specimens aged 28 days were placed in the split Hopkinson pressure bar testing apparatus and a dynamic load was applied. The measured peak dynamic compressive strength of the cemented sandfill was 10.6 MPa (1540 psi) and is approximately twice the static unconfined compressive strength (UCS) of 5.5 MPa (800 psi). These test data showed about 95% of the initial energy was reflected away from the backfill and only 5% of the energy was absorbed. This may help to explain why backfilled stopes could withstand seismic events up to 3.5 Richter magnitude (Ml). When a compressive rockburst wave impacts a stope a large amount of the stress and energy is reflected away. The reflected wave is a tensile wave which creates tensile cracks and spalling in the entire wall of the stope. The backfill supports the damaged wall rock and holds it in place. Some of the stress and energy of the rockburst is transmitted into the backfill and because the backfill is being dynamically loaded it has a strength that is twice its static value and absorbs a substantial amount of rockburst energy. Although mining in deep underground mines is an extremely hazardous occupation, the use of underhand mining with cemented backfill for static and dynamic ground control increases the safety of the workers.

May 1, 2007

By T. G. Joseph, K. Barron

A strain-softening constitutive relationship is introduced that describes the post-failure stress-strain curve for rock regardless of whether the rock is intact or broken. The core of this relationship is an “apparent friction” concept that relates the post-failure apparent cohesive and frictional characteristics of the rock to the strain. The relationship can be determined for a given rock via a series of triaxial strength tests establishing the peak strength and corresponding strain for a range of confining pressures, together with the determination of the base angle of friction via a simple tilt test. The postulates and assumptions used in deriving this relationship are verified from results of tri-axial tests on both intact and broken rock. This strain-softening relationship is then applied to coal. Having determined the post-failure stress-strain curve for coal specimens, this information can then be used in a finite element program, such as Phase 2, to examine the post-failure characteristics of coal pillars. Using example data, the strength of coal pillars of different width/height ratios are estimated and compared with well-known empirical pillar size-strength relationships. In addition, the post-failure stress-strain behaviour of a coal pillar is compared with an empirical relationship reported in the literature.

Jan 1, 2003

By P. J. Urso

"This paper discusses the mining problems encountered at the Fording River coal mine to date, and how they have been solved. All of the production now comes from surface mining, but underground hydraulic mining is planned and briefly described. Other facets of the operation, including markets, equipment and personnel, are covered. IntroductionFording Coal Limited was formed in 1968 to mine and market metallurgical coal resources held by the company in the East Kootenay region of southeastern British Columbia. The company, at its Fording River operations, holds approximately 48,000 acres of coal lands, having an estimated 2.0 to 3.0 billion long tons of metallurgical coal in place. (Although not a point for further discuss ion in this paper, the company also holds approximately 1.0 million acres of mineral rights. These consist primarily of coal in Alberta, potash and coal in Saskatchewan, and minor industrial mineral holdings of limestone, salt and bentonite in the three western provinces.)Fording Coal is owned 60% by Canadian Pacific Investments Ltd. and 40% by Cominco Ltd. Inasmuch as Cominco itself is owned approximately 54% by CPI, it is seen that the effective CPI ownership of Fording is about 82%. The company, originally staffed and managed by Cominco, has been independent since January, 1978, with its own board of directors, management, staff and employees.The company's head office is in Calgary, Alberta. The Fording River operations are located approximately 45 miles north of the Crowsnest Pass, near the Alberta/British Columbia boundary, only 95 air miles and 200 road miles from Calgary.A contract was signed in 1969 with the Japanese steel mills to provide 45 million long tons of metallurgical coal over IS years, commencing in 1972 at an annual rate of 3 million long tons per year. Despite some start- up difficulties, the mine and plant facilities achieved their rated capacities in 1975, producing and shipping at the 3-million-Iong-ton level. The coal specifications are shown in Table I."

Jan 1, 1980

By Jacque Turgeon, Gontran Foy

"The Mineral Research Centre of the Quebec Department of Energy and Resources has worked extensively on the development of a dry process to extract pure mica flakes from a phlogopite ore. The liberation of mica from the gangue is effected basically by impact crushing, and the ground ore is screened into several fractions, each having a fairly narrow range of grain size. Each sized fraction is then fed to an air separator where heavy grains are separated from light flaky grains. Heavy fractions are returned to hammer mills where gangue minerals are ground finer and blocky mica particles are exfoliated. A second stage of screening is performed and each fraction is sent to an air separator. This sequence is repeated until mica products are virtually free of gangue. These different fractions are then treated in a cage mill in which mica flakes undergo a more orderly exfoliation along cleavage planes. The ground mica is again submitted to a final screening stage, after which each fraction constitutes a final commercial product.This process permits the recovery of about 70% of the mica contained in the ore. The over-all process will be described along with technical details of each unit operation. Recent work on a wet grinding method to produce very fine mica will also be discussed.IntroductionRecords of production of mica in Quebec date back to 1886. Production has been more or less continuous since that time, with peak activity during the war years. Production was interrupted in 1966, but started again in 1972 when Marietta Resources and Laviolette Mining and Metallurgical Corporation started their joint operation in Canton Suzor, northwestern Quebec. Mica deposits of more or less importance exist in different parts of Quebec, of which three have attracted attention in recent years: the Canton Suzor deposit, the Canton Lamy deposit and the Canton Chasseur deposit. The Suzor orebody was first identified by Carl Faesler in 1936, who described the rock as ""brown biotite in flakes half an inch in diameter, with interstitial augite, apatite and feldspar""."

Jan 1, 1982

By K. Enns, J. J. Byerley

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

Jan 1, 1984

By Rory S. McLaren

"Cost per ton as it relates to mobile underground vehicle maintenance and repair is invariably astronomical. The reason: the mechanic replaced a ten micron filter with a 250 micron filter because it appeared to be physically identical; the purchasing agent bought ""Brand X's"" filter because it was 25% cheaper- the result, a filter life 30% less; the hydraulic pump was sent for repair at a cost of $2000.00 and failed shortly after installation; pumps are failing because there is no testing equipment available in the workshop.This paper will identify a number of the common pitfalls resulting in high costs, and offer solutions to bring these costs to within acceptable limits.The following key issues will be discussed:A. Genuine parts replacement versus ""Brand X""B. Evaluating outside repair shopsC. The influence of environmental conditions on optional equipmentD. Personnel trainingE. Servicing and testing equipmentIntroductionThere is an old English aphorism, ""Look after the pennies, the pounds will look after themselves"".This paper is aimed at the pennies.Genuine Parts Replacement versus ""Brand X""High interest rates and floundering mineral prices are forcing many equipment owners and operators to purchase ""Brand X"" or ""Pirate"" parts in order to survive. ""Pirate"" part manufacturers invariably offer lucrative discounts which are most appealing to the average purchasing agent whose responsibility it is to save money. Unfortunately, in most cases, there is a tradeoff involved; when the price drops so does the quality, which can adversely affect owning and operating costs. Unless totally obvious, ""original"" or ""pirate"" part metamorphosis requires scrupulous analysis by competent individuals.Hydrostatic transmissions have been used successfully for many year s in various industries. They found their way into mobile underground loaders in the early seventies and have since become very unpopular in mining circles due to their apparent ""inherent unreliability"" and near ""prohibitive"" repair costs. The big benefit of the hydrostatic transmission is compact component packaging which enables the machine to work in very small headings."

Jan 1, 1983

By L. A. Homeniuk, R. Bonnar

"The Athabasca Basin has been the scene of an intense exploration effort since the late 1960s, resulting in the establishment of this area as one of the major uranium districts in the world.The A thabasca Group is of Helikian age and unconformably overlies metamorphic rocks of Aphebian and Archean age. Most of the known uranium deposits have a close spatial relationship with the unconformity, graphitic meta-sediments, major northeast-trending structures and the basin edge. It should be noted that, in regard to the latter, some of the Cluff Lake deposits are exceptions.The pre-Helikian rocks underlying the Athabasca Group have been divided into six Iithostructural domains. The known uranium deposits are concentrated in the Wollaston and Mudjatik domains in the southeastern portion of the basin.The orebodies typically have a narrow high-grade portion below the unconformity and a broader, lower-grade disseminated zone in the overlying sandstone. Over-all grades average over 1% U3O8 and our estimate of known reserves totals more than 400 million pounds of contained U3O8. Some of the deposits have high concentrations of other metals, including nickel, arsenic, cobalt and gold. Ubiquitous chlorite and clay alteration is characteristic of the orebodies.Other Proterozoic basins in Canada of similar ages and having analogous geological settings to the Athabasca have received far less attention. Although little of the known uranium mineralization in these basins is related to the Helikian unconformity, there may be an exploration potential for deposits similar to those of the Athabasca basin.IntroductionThe Athabasca sedimentary basin is located within the Churchill Structural Province of the Canadian Shield in Northern Saskatchewan. The basin is elliptically shaped and is approximately 800,000 square kilometres in area.The objective of this paper is to summarize the various elements in the genesis of the unconformity-type uranium deposits of the Athabasca Basin and to evaluate the comparative potential of other Proterozoic basins to host similar unconformity-type deposits."

Jan 1, 1982

By W. P. Armstrong, O. Owens

"The process of arriving at the size and grade of· (a) a newly discovered body of mineralization, (b) a potential ore resource, (c) an orebody proposed for mining, or (d) the ore reserves in a mine, requires fundamental geological, and geometrical determinations as well as physical and chemical analyses. This paper outlines geological and geometrical features considered critical, in the authors' experience, in realistic reserve determination. These are discussed under the headings ""The Four Cs"". They include the Character, type or nature of the mineralization; the Continuity of various types of mineralization in the deposit; various key concerns in the Calculation besides the mathematics; and the Classification section which refers to basic considerations in classifying a mineral estimate. It is suggested that the responsibility for the calculation of a Resource or Reserve should be that of a geologist experienced in the ore type under review. Further, it should be the responsibility of the board of directors of the company owning the deposit to ensure that a sufficiently experienced person is chosen to carry out the process. IntroductionThe key issue of ore reserves is that they are intended as, a clear-as- possible statement of metal in place in a mineable orebody. Precise, widely understood definitions help convey understanding of the figures, but accuracy requires careful geological input before the calculation is made and a definition is applied. Many recent new mining operations in Canada have experienced serious shortcomings between original ore reserve figures and what was mined. This suggests deficiencies in the actual tonnage and grade calculated in advance of production. The authors suspect that much of the problem is due to a less-than-adequate outline of the orebody before calculating reserves for production or alternatively, treatment of grade and thickness data without regard to an orebody outline. Careful consideration of mineralization and ore continuity is one of the most important aspects of ore geology. Ore reserve calculation should be more than a mathematical exercise."

Jan 1, 1994

By Terry J. Briggs, Ian J. Kelso

"Abstract- The Century mine in northwest Queensland,Australia, is a major sediment-hosted zinclead- silver orebody, located within the western Mount Isa Basin. Stratiform, carbonaceous shalehosted mineralization is developed within Proterozoic shale and siltstone sequences of the Lawn Hill Formation. CRA Exploration Pty Ltd (CRAE) discovered the Century deposit in 1990 and open pit mine development commenced in 1998 under the ownership of Pasminco Century Mine Limited (PCML). The deposit contains an identified mineral resource of 105 Mt @ 12.1% Zn + 1.7% Pb + 46 g/t Ag (Broadbent and Waltho, 1998) which is currently being mined at a rate of 5 Mt/y.In December 1998, an exothermic reaction was observed between explosives spilt onto shale drill cuttings from a blasthole. This reaction is referred to as ‘reactive ground’ and has the potential to cause premature detonation of explosives in a charged blasthole with catastrophic consequences. The incident led to a subsequent geological and geochemical assessment of the different rock types at the Century deposit and their potential reactivity with ammonium nitrate-based (AN) explosive products. This assessment was conducted in an attempt to characterize zones safe for blasting with uninhibited AN-based explosive products. A direct result of this study is a set of procedures outlining the use of different AN-based explosives in areas defined as potentially reactive or non-reactive for the different lithologies present. Black shales contained in both the waste and mineralized sequences contain the sulfide mineral pyrite (FeS2), which is thermodynamically unstable with AN contained in commonly used explosives. The potential reactivity of partially weathered pyrite can ultimately result in the decomposition of an AN-based explosive. It was determined that only pyritic black shales showed any potential to react with AN, irrespective of their position in the stratigraphic sequence. Other lithologies present at Century, including Proterozoic sandstone and Cambrian limestone, are classified as non-reactive with AN. This is a geological risk management situation present at the Century mine."

Jan 1, 2001

By William A. Napier

The Mantaro Phosphate Property is located ~ 250 km east of Lima, Peru in the Andean altiplano near the city of Huancayo, Junin District. The Mantaro deposit is a mineralized zone of phosphatic rock currently defined by surface outcrops, trenches and drilling extending over a strike length of more than 30 km and a width of more than 5 km covering ~27,700 hectares. Mineralization is exposed as three roughly parallel exposures (?mantos?) trending in a northwest-southeast direction along the Mancaspico syncline. Estimated mineral resources1 contained in Manto 1 of the Property (4% P2O5 cut-off) as of February 21, 2010, are: Measured 5.548 million tonnes @ 10.8% P2O5 Indicated 33.975 million tonnes @ 9.9% P2O5 Measured + Indicated 39.523 million tonnes @ 10.0 % P2O5 Inferred² 376.265 million tonnes @ 9.0% P2O5 1Tonnes rounded to the nearest 1,000 and grade to 1 decimal place. 2Inferred material reported with no cut-off and an assumed grade. There is considerable potential to expand the resource base. Mantos 2 and 3 of the deposit have been geologically mapped and exhibit surface mineralization widths similar to Manto 1. Given that the deposit is of marine sedimentary origin, it is reasonable to infer that comparable grades and depth of mineralization are present within Mantos 2 and 3. Based on this assumption, the potential mineral deposits within Mantos 2 and 3 are estimated to be approximately: Manto 2 425-435 million tonnes @ 9% P2O5 Manto 3 280-290 million tonnes @ 9 % P2O5 These potential quantities and grade are conceptual in nature, there has been insufficient exploration to define a mineral resource and it is uncertain if further exploration will result in these targets being delineated as a mineral resource. However, should such conceptual resources be confirmed by trenching and drilling, the Mantaro Phosphate Property would rank as one of the most significant phosphate deposits in the world.

May 1, 2011

By M. Leroux, S. R. Rao, J. Kim, J. A. Finch

"Continuous in-plant testing of collectorless Cu/Pb bulk flotation on Lyon Lake ore at Matlabi Mines Ltd. Was conducted using a portable circuit based on 5 L mini flotation cells. It is concluded that collectorless Cu/Pb flotation is a reliable phenomenon for this ore over the usual range of plant operating conditions.IntroductionFlotation of some sulphide minerals without the use of conventional collectors (e.g. xanthates) is now widely recognized. The requirement appears to be some degree of oxidation, although the nature of the surface product formed is still uncertain (Luttrell and Yoon, 1984; Buckley and Walker, 1988). The phenomenon has been termed ""collectorless"" or ""self-induced"" flotation. One of the minerals most responsive to coUectorless flotation is chalcopyrite; in contrast pyrite and sphalerite show little response and galena usually shows intermediate response (Hayes et al., 1987; Shannon and Trahar, 1986).Most of the work on collector1ess l1otation has involved single mineral or batch flotation on ore samples. There are only occasional references to collector1ess l1otation under plant conditions (Sandstrom and Jonsson, 1988; Vargas, 1990; Boyce et al., 1970). Creating and maintaining the appropriate oxidation conditions and differences in water quality are among the reasons why the phenomenon may not transfer readily to the plant (Grano et al., 1990). Periodically from the spring of 1989, Mattabi Mines Ltd. ran full-scale tests of collector1ess bulk CulPb flotation while treating Lyon Lake ore*: the observations confirmed the laboratory finding that chalcopyrite and galena floated without collector (Leroux et al., 1989).To explore this finding continuous in-plant testing using mini flotation cells was conducted which is the subject of this paper. The main objective was to determine if collectorless flotation was a reliable phenomenon over the expected range of redox conditions in the feed pulp to bulk CulPb roughing. As background, the previous work (Leroux et al., 1989; Martin, 1988) is briefly reviewed."

Jan 1, 1994

By I. Stanoev, V. S. Stoilov, I. Gradinarov, E. D. Visariev, I. A. Bonchev, Aurubis Bulgaria

"Aurubis is the leading integrated copper group and the world’s largest copper recycler. In Copper smelter Aurubis Bulgaria (Pirdop), the residual copper in the slags from Flash furnace and Converters is recovered by flotation. The slag processing comprises: pit cooling, crushing, two stages grinding (autogenous and ball) and flotation. The copper concentrate is thickened and then is filtrated by vacuum disk filter. The thickener overflow is sent to settler for additional clarification. A resent throughput increase resulted in higher solid content in the thickener overflow due to insufficient thickener area. Different scenarios to overcome the issue were evaluated (new thickener, reagents and reconstruction). An increase of the thickening area by installation of lamella modules was chosen as the most promising option. Three lamella modules (1 m3 each) were installed in conventional thickener for the test. Number of sampling campaigns was done to evaluate the effect on solid content in overflow. Parameters of the dewatering cycle were collected during sampling campaign. The products grain size distribution was defined - thickener feed, thickener overflow with and without lamella. The thickener overflow with lamella modules has 2.12 g/L less solid content. The decrease was 71.8%. According to the tests results, the whole conventional thickener was reconstructed with lamella modules. The thickener area was increased by more than 400 m2.INTRODUCTIONIn Copper smelter Aurubis Bulgaria, the copper in slag from the Flash furnace and the Converters is recovered by flotation. The scheme of slag processing is crushing, two stage grinding (autogenous and ball) and flotation. Till 2010 the grinding cycle in the plant was in two stages: the first stage was AG Mill 70×23 working with a classifier and the second stage was ball mill 3.6/5.5 working with a hydrocyclone. In 2010 a new AG Mill 65×78 with hydrocyclone was put in operation in order to increase throughput of the plant. The second stage of the grinding cycle was not changed."

Jan 1, 2016

By Robin Perry, Claude Bazin

"Discrete transfer functions which use the grinding circuit feed tonnage to predict mass flowrates at reagent addition points in a flotation circuit were calibrated using a dynamic grinding/flotation circuit simulator. Predicted mass flow values are multiplied by reagent addition ratios to obtain actual reagent flow. The transfer functions are currently integrated into the distributed control system of Les Mines Selbaie.IntroductionThe development of adequate tools for the control of flotation processes is a continuous challenge. Since the early 1970s there have been numerous publications dealing with practical aspect of control of flotation processes. Most plants use a combination of feedback and feedforward controls to reduce the effect of the following flotation process disturbances (McKee, 1991):• changes in throughput;• changes in feed grade;• changes in particle floatability (size, liberation, surface oxidation ... ); and • deliberate changes of setpoint;Feedforward control manipulates variables such as reagent and/or air flow rate to attenuate the effect of disturbances such as changes of feed rate and mineral content. The feed forward strategy is driven by measurements of these disturbances. Feedback control is used to maintain process variables to targeted set-points of concentrate or tails grades. The feedback control action is driven by deviation from the set-point, caused by a deliberate change of set-point or disturbances.This paper proposes a method to improve feed forward control schemes by the addition of a simple model for solids transportation. The feedforward strategy considered in this paper is the ratio type, in which the manipulated variable is changed according to a predefmed ratio between this variable and the measured disturbance. A typical example is the ratio of the reagent addition to mass flow of ore.The paper reviews the state of the art in feed forward control strategy applied to flotation processes and describes the method used for predicting mass flow rates. The last section shows an application of the method in the Les Mines Selbaie flotation circuit."

Jan 1, 1994

By J. Karonen, M. Tiihonen, J. Guentner, L. Haavanlammi, Outotec GmbH, E. Kolehmainen

"Rare earth elements have obtained significant attention during the last few years due to predicted increase in their demand. Several projects worldwide are at pre-feasibility or feasibility stage aiming to commence production. Deposits of rare earth elements are typically complex and multi-metallic of nature. This means that production processes are often also complex and therefore, various metallurgical unit processes are needed. Outotec’s equipment and technology portfolio is very comprehensive and includes hydrometallurgical and pyrometallurgical apparatus and processes applicable to the efficient exploitation of rare earth deposits. Outotec has gained useful experience relevant to the processing of rare earths through several assignments including those for Alkane Resources Ltd. (Dubbo Zirconia Project), Greenland Minerals and Energy Ltd (Kvanefjeld Project), Frontier Rare Earths Limited (Zandkopsdrift project), Tantalus Rare Earths AG (Madagascar), Quest Rare Metals (Strange Lake project) and Orbite Aluminae Inc. (HPA project). The hydrometallurgical test work of two process flowsheets is presented in the paper. A roasting or acid baking step is common to several proposed rare earth projects. In the past, rotary kilns have been used, but Outotec has developed a new process concept to handle the rare earth material in fluid bed reactors. The basis for this development is long experience in fluid bed technology of Outotec in Germany. One advantage of fluid bed roasting is the higher throughput per unit. In combination with the roasting and baking, Outotec offers the gas cleaning and acid plant and provides a complete and closed concept.INTRODUCTIONRecovery of rare earth elements (REE) has obtained significant attention during recent years. It has been estimated that their demand will be boosted because of their need in many technology areas. REE can be utilized in magnets, batteries, displays, catalysts, optical devices etc. (Jordens, Cheng, & Waters, 2013; Zhang & Edwards, 2013). The production of REE is focused in China, which means that production outside of China is very scarce. However, there are multiple active development projects worldwide working towards production of REE containing products outside of China (Chen, 2011)."

Jan 1, 2016

By Kazuteru Tozawa, Robert G. Robins

"The stability of calcium arsenate is discussed in relation to the possible misuse of lime in the treatment of gold processing waste waters. Stability diagrams have been derived and experimental results cited to show that calcium arsenate has a higher solubility in neutral to alkaline solution than has previously been recognized and this solubility is further enhanced by the presence of carbon dioxide, bicarbonate or carbonate.IntroductionThe removal of arsenic from gold mine waste waters has been of interest for more than thirty years, but with the recent emphasis on clean water standards there has been renewed activity in relation to that problem. The processing of gold-bearing sulphides which contain arsenopyrite and other complex arsenic sulphides is well established. Initial roasting to oxidize the sulphides leaves the arsenic in the form of both arsenic and arsenic, in which forms it is soluble in the subsequent leaching stage. Further oxidation of the leach liquors is required before the well-established procedure of precipitating calcium arsenate with lime, which is carried out despite an immense lack of knowledge of the calcium-arsenic-water system.The solubility product and free energy of formation for Ca3(AsO4)2, which are to be found in recent and reliable sources of data, originate from the work of Chukhlansev, whose experimental determination of the concentration of calcium from the solubility of calcium arsenate in solutions of various pH yields the results plotted in Figure 1. This is the work which has resulted in a wide acceptance of the ""insolubility"" of calcium arsenate and the use of lime to stabilize arsenic in that form.Laguitton attempted to further elucidate the chemistry of the lime addition method for treating arsenical waste waters from gold processing operations. The low solubility product for Ca3(AsO4)2 was the basis for his examination of likely chemical equilibria in the system. Laguitton and other workers have not considered atmospheric carbon dioxide as an important component in this system."

Jan 1, 1982

By T. Hadley, Northern Minerals Ltd, C. S. Griffith, T. A. Safinski, K. H. Soldenhoff, M. Fainerman-Melnikova, A. Manis

"ANSTO Minerals and Northern Minerals have been working together since 2012 on the process flowsheet development for the Browns Range project for the recovery of the heavy rare earths (Dy – Lu, + Y). Initial efforts were directed toward defining the most efficient and direct flowsheet for the Preliminary Feasibility Study (PFS), issued in June 2014, then towards the Definitive Feasibility Study (DFS), issued in February 2015. These goals were achieved by undertaking comprehensive laboratory and continuous piloting programs. Further improvements to the flowsheet following the DFS have been made. This publication provides an overview of the evolution of the process flowsheet based on these laboratory and piloting programs from the PFS through the DFS and beyond.INTRODUCTIONNorthern Minerals Ltd (Northern) has been working on developing their flagship project at Browns Range for the recovery of the heavy rare earth elements (HRE, Dy – Lu, + Y). The project is located in the north of Western Australia as shown in Figure 1. The Total Mineral Resource at the project is currently estimated at 8.98 Mt @ 0.63% total rare earth oxides (TREO) comprising 56,663 t of contained TREO using a cut-off grade of 0.15% TREO. Of the Total Mineral Resource, 58% is classified as Indicated Resource, with the remainder in the Inferred Resource category.The deposit is characterised by breccia-hosted, hydrothermal, HRE-rich, xenotime mineralisation. The main gangue mineral associated with the xenotime is quartz. The distribution of rare earths (RE) observed for the xenotime mineralisation at Browns Range is presented in Figure 2. Extensive test work has shown that the xenotime can be readily beneficiated to between 20 – 40% rare earth oxide (REO) using a process consisting of crushing and grinding, followed by magnetic separation and flotation steps. Continuous piloting of this process was conducted on ~80 t of trench-sourced ore in late 2013 at SGS Perth, to produce ~2 t of ~20% REO mineral concentrate (MC) for hydrometallurgical testing. The composition of the MC produced during piloting is presented in Table 1."

Jan 1, 2016