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By C. Edwards

"The processes for rare earth (RE) extraction include the decomposition of RE ore concentrate minerals, and the concurrent or subsequent leaching of the rare earth elements (REEs) from the decomposed minerals. Ore beneficiation concentrate can be decomposed by, for example, acid roasting, caustic cracking, and chlorination. The REEs can be selectively extracted. The nature of the REE extraction process depends on the concentrate mineralogy and the targeted products. Based on the experience of the Saskatchewan Research Council (SRC) in RE processing, this paper reviews REE extraction from the major RE minerals, including bastnaesite, monazite, xenotime, ion-adsorption clay, allanite, cerite, and eudialyte. An update on the development of RE extraction processes is also provided.INTRODUCTIONRE processing usually involves two operation stages, physical processing and chemical processing. Physical processing, also known as ore beneficiation, separates the RE minerals from gangue minerals to produce an RE mineral concentrate. Chemical processing, which includes extraction and separation processes, converts the RE mineral concentrate to an RE compound which is either an end product or an intermediate product for the subsequent production of individual REEs or other compounds. The RE extraction process uses one or more reagents to decompose the RE minerals and to leach the REEs into solution. The RE separation process uses solvent extraction, ion-exchange, or chemical precipitation to produce either rare earth oxides (REOs) or individual REEs. The authors have previously reviewed RE ore beneficiation processes (Zhang & Edwards, 2012). This paper focuses on extraction processes for a variety of RE minerals. Table 1 gives the chemical compositions of the RE minerals mentioned in this paper. The varieties of RE extraction methods use many different reagents. These reagents are mainly inorganic acids, alkalis, salts, and chlorine gas. The commonly used acids include sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3). Sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) are the most common alkalis. Salts include ammonium sulphate ((NH4)2SO4), ammonium chloride (NH4Cl), and sodium chloride (NaCl). HCl is normally used to extract RE from silicate ore minerals such as allanite and gadolinite. The alkalis and H2SO4 are mainly used to leach REs from phosphate ores minerals like monazite and xenotime. The carbonate ore RE minerals such as bastnaesite can be treated using either acids or alkalis. HNO3 is mainly used to leach eudialyte and apatite. The extraction of REs from ionadsorption clay deposits uses salt solutions. Chlorine gas (Cl2) is exclusively used in the RE chlorination process which can be used to treat any RE minerals."

Jan 1, 2012

By Bahaa Hussein

Considerable number of methods and procedures has been introduced for trending and progress reporting of engineering, procurement and construction projects. This paper introduces a novel method, designed to augment the set of indices for measuring schedule performance. The concept behind the developed method is to provide early warning by dynamically evaluating the schedule cumulative impact of construction projects. The proposed method is designed to highlight the gradual deterioration in schedule status resulting in a cumulative impact due to the aggregation of small delays encountered during the execution of non-critical activities, and can be used as an add-on utility to existing software systems that perform CPM scheduling. The proposed method is based on a developed formulation for quantification of the Schedule Compression Index, which takes into consideration the remaining project activities durations. The index is developed based on periodic comparisons of ?Current Schedules? and the project ?Baseline Schedule? using the summation of the remaining activities durations. A numerical example is presented to demonstrate the application and capabilities of the developed method. It is expected that the developed index together with other schedule performance indices would be of value to decision makers and members of project teams.

Aug 1, 2013

Weekly Capacity ? Current Schedule Rate (198.5 tonnes / hour) X Skip Time (112.7 hours) X Effectiveness (85%) = Weekly Capacity (19,015 tonnes) Capacity Conclusions - Existing hoists optimized are best option for Fraser Morgan (>20M + schedule for other). - Peak will have to be managed. - Critical to have equipment & infrastructure in best possible condition to ensure reliability.

Feb 1, 2008

By W. Curlook, L. M. Pidgeon

THE PURPOSE of this investigation was to study part of the ternary system Co-Fe-S. Jensen ( 1) established the solubility limits of sulphur in pyrrhotite. The compound with 61.7 per cent Fe, corresponding to a formula Fe12S13, was found to melt congruently at l,192°C. Hulsmann and Weibke(2) determined the Co-S phase diagram from O to 35.2 per cent S. The solubility limits of sulphur in the com-pound Co(l-x)S were not determined. The initial object of the present in-vestigation was to determine the composition at which the compound Coci-xiS melted congruently. Once this was ascertained, it was decided to investigate the ternary system Co-Fe-S from the region of 100 per cent Co(1-x) S to the region of 100 per cent Fe12S13.

Jan 1, 1953

By Desmond M. Levins, Reginald K. Ryan

"Removal of radium from uranium tailings would substantially lessen their environmental impact because it would eliminate, or greatly reduce, the hazards arising from radon emanation, leaching of radium, dust dispersal and gamma radiation. A process is described to extract radium from tailings by leaching in 3M Nael solution. The radium can be rapidly leached at ambient temperatures by either multi-stage contact in agitated vessels or washing on a tailings filter cake. Extraction efficiencies ranging from 80 to 94% have been measured for tailings derived from a number of Australian ores.Methods for radium recovery from the leach solution by precipitation, ion exchange and adsorption have been examined. Precipitation as barium/radium sulphate appears to be the most suitable approach. A possible flow diagram for the process is proposed which involves recycle of the saline leach liquor.IntroductionDisposal of mill tailings is the most contentious environmental issue facing the uranium mining industry. The conventional approach to managing tailings is to store them in a dam above ground. Attempts have been made to stabilize some tailings piles by physical or chemical methods. In a few cases, the tailings have been covered with earth and revegetated. However, most tailings piles from abandoned mills are in a neglected state and subject to the erosive and dispersive forces of nature. The cost of remedial action is high. The United States Department of Energy (DOE) has estimated that it will cost up to $130 million to rehabilitate abandoned mill sites in the U.S .A..Environmental authorities are now insisting that uranium mining companies improve their methods of tailings disposal. In the United States, the preferred approach is burial, either in mines or in specially excavated pits. Tailings retention systems as operated in Canada are regarded as storage facilities until an acceptable method of disposal is found. In Australia, the Fox Commission recommended that tailings from the Ranger project should be returned to the open-cut mine. Returning tailings to the mine has considerable merit, but it is not always a viable option. In many underground operations, it is not physically possible to fit all the tailings in the worked-out mine. In other cases, the groundwater hydrology of the mine may be unfavourable."

Jan 1, 1980

By David Laing

Completion of a Feasibility Study represents a major milestone in the development path of a mine, and one which typically triggers a need for project financing. Obtaining funding for construction relies on a positive Feasibility Study and a host of other related activities. This paper looks at the financing process and work required to support it, during and after the Feasibility Study, and bring it to a successful closing. It will include comment on the significance of permits, environmental plans, construction contracts, offtake arrangements, hedging, insurance, and others requirements to support a financing plan.

May 1, 2010

By Gyeonghye Moon, Inhyeok Choi, Jyothi Rajesh Kumar, Jin-Young Lee

"This paper deals with the recovery of the tungsten and vanadium from spent SCR catalyst leach liquors by different hydrometallurgical methods. The first part consists of pressure leaching of spent SCR catalyst using caustic soda followed by metal recovery by liquid-liquid extraction. In a leaching process, the following experimental parameters were tested and optimized: NaOH, particle size of feedstock, temperature, and solid to liquid ratio. The optimum condition for leaching of tungsten and vanadium was under the following conditions: NaOH 3 mol/L, temperature 250°C, particle size <300 µm, and solid to liquid ratio 0.4. From these optimum conditions in this experiment, the dissolution efficiency of vanadium and tungsten was 91.5and 87%, respectively. Liquid-liquid extraction following commercial extractants were tested: TBP, Cyanex 272, D2EHPA, Aliquat 336, Primeme JM-T, Alamine 308, Alamine 304-1, and methyl-tri-octyl-ammonium chloride. The conditions for both valuable metal recoveries were optimized.INTRODUCTIONSelective Catalytic Reduction (SCR) catalyst has become the most effective to reduce nitrogen oxide (NOx) emissions from stationary segments such as power plants and waste incinerations around the world due to the reinforcing regulatory trend and emerging environmental issues (Forzatti, 2001; Spivey, 2002; Li et al., 2011).Currently, the most widely used SCR catalyst is V2O5-WO3/TiO2 system due to its great catalytic properties (Li et al., 2011; Marshneva et al., 1995; Marbergeret al., 2015). In general, the composition of the SCR catalyst used in the stationary application is 0.5 to 1 wt% of V2O5and 7 to 10 wt% of WO3(Marberger et al., 2015; Chen &Yang, 1992, Vuurman et al., 1991; Alemany et al., 1991). Currently spent SCR catalysts are treated as waste and disposed of in landfills. This causes a lot of waste of secondary resources of vanadium and tungsten. In terms of industrial value of vanadium and tungsten (Gupta &Mukherjee, 1990; Moskalyk &Alfantazi, 2003) and reduction of pollutant emissions, it should not be disregarded for their recovery for their material recycling from spent SCR catalyst. However, investigations for recovery of metal values from spent SCR catalyst has been rarely carried out."

Jan 1, 2017

By Mostafa Benzaazoua, Emilie Ré, Raphaël Mermillod-Blondin, Hassan Bouzahzah, Jean-François Wilhelmy, University of Québec in Abitibi-Témiscamingue

"We analyzed two copper and lead flotation concentrates from the LaRonde mill using MLA technology (Mineral Liberation Analyzer) to identify the contaminants and to quantify their size and liberation. The MLA mineral quantification was compared with traditional mineralogical techniques (Scanning Electron Microscopy, Optical Microscopy, X-Ray Diffraction and Chemistry). The accuracy of MLA data was then quantify in application to metallurgical decision (mineral identification, mineral quantification, particle sizing and liberation quantification). We prepared five well-known materials from pure minerals and analysed them by MLA. MLA concentrates analyses showed the lead concentrate is mainly contaminated by pyrite and sphalerite. These minerals are liberated above 70 % and present a floatable size around 15 to 35 µm. Surface activation by dissolved lead from galena is therefore assumed for these contaminants. The analyses of the known samples show that mineral quantification and size distribution given by the MLA are consistent with the chemical analyses and the laser particle sizer. The liberation measurement is affected by the stereological effect. Modelling quantifies the overestimation of the particle liberation. Based on the modelling, the stereological shift on liberation should not impact metallurgical conclusions on the concentrate contaminations.INTRODUCTIONTo face the diversity of mineral processing challenges, the process mineralogy includes phase quantification, measurement of mineral size, liberation by exposure and by grade, association, surface contact proportion and texture. In the last decades, two SEM commercial tools emerged: MLA and QEMSCAN R. Both are based on specific combinations of backscattered electrons and X-ray images as well as image analysis routines developed at CANMET (Petruk & Pinard, 1976, Petruk, 1989), CSIRO (Frost, O'Hara, Suddaby, Grant, Reid, Wilson & Zuiderwyk, 1977, Reid, Gottlieb, MacDonald, & Miller, 1984) and JKMRC (Hall, 1977, Gu & Sugden, 1995). Recently, TIMA (TESCAN) and Mineralogic MiningR (ZEISS) supplied automated mineralogy for mining industry (Bouzahzah, Benzaazoua, Graham & Cropp, 2015, Gottlieb & Dosbaba, 2015a). In parallel, home-made routine were developped to resolve mineralogy challenges in mineral process but also in geometallurgy and mining environment (Kahn, Mano, & Tassinari, 2002, Knight, Klassen & Hunt, 2002, Mermillod-Blondin, Benzaazoua, Kongolo, de Donato, Bussiere & Marion, 2011, Hunt & Bradshaw, 2015). SEM mineralogy become essential to operation by setting units on mine sites (MacDonald, Latti, Adair, Bradshaw, & Dunn, 2011, Goergen et al., 2013, Dobbe et al., 2014, Gottlieb & Dosbaba, 2015b)."

Jan 1, 2016

By W. G. Millar

Until a fire occurs, insurance and prevention work are often looked on as unavoidable necessities, but as insurance is back of all business credit, it is essential to know that in case of damage money will be available to cover the loss; while the interruption of production, often caused by a fire, brings home the realization that if prevention work avoids such an interruption, it is well worth while. Fire insurance is a legal contract guaranteeing the payment of large amounts to an owner, but it is possible there is no other important contract that receives so little consideration. Although previously carried on elsewhere, it is only of recent years that insurance engineering has been actively followed up in Canada, with inspections of an owner&apos;s property carried out for his benefit. Now inspections of this kind are made, advice on fire prevention and protection work ?is available, reports with recommendations with regard to the above are furnished periodically, and with this method applied the owner receives the broadest possible cover and security at the lowest cost. Rates are set by the underwriters by rating schedules which charge for defects in a building and allow credits for protection and other favourable features . These schedules are based on the past record of loss of mining properties as a class, so that a fire in another mining property indirectly affects you, but the amount paid is reduced in proportion as your property is improved. The writer feels, from personal experience, that there is no industry where fire prevention receives more attention than the mining industry, and it is a pleasure to advise that, due to this co-operation, some reduction in the basis rates for mining risks is now being made by the underwriters.

Jan 1, 1928

Although Canadian bentonite is competitive in quality for most uses, it has not been accepted for the pelletizing of iron ore concentrates. In 1962, Canada consumed about 10,000 tons of imported bentonite for this use. By the end of 1965, the planned domestic consumption for this purpose alone will probably be more than 100,000 tons a year, valued at about $3 million. Consequently, a challenge exists for the establishment of a Canadian source of high-quality bentonite for pelletizing. Such a bentonite would also be suitable for the two other major applications -well drilling and foundry use. Brief mention is made of such topics as the identification, 1noperties, occurrences, exploration, applications, technology and laboratory testing of this clay. In particular, the type of bentonite in demand, the geological horizons warranting exploration, and simple preliminary test methods are discussed.

Jan 1, 1964

By M. Tanaka, T. Oishi, K. Koyama, S. Alam

"A novel hydrometallurgical process for copper recovery from waste printed circuit boards has been proposed, which consists of selective leaching of copper metal as Cu(I) by Cu(II) in ammoniacal alkaline solution, purification, and electrowinning. The distinct feature of this process is much lower power consumption during the electrowinning than that during the conventional one from acidic copper sulfate media, because the deposition of copper metal from Cu(I) at the cathode and the oxidation of Cu(I) to Cu(II) at the anode take place in the present method. In the laboratory-scale tests using waste printed circuit boards, high purity copper which contains 1.1ppm of impurities was obtained in a chloride system. INTRODUCTIONThe recovery of various metals from waste materials is an important issue in order to conserve the environment and metal resources. Copper is used for cables, electric appliances, etc., and is currently a very important material for industries and will continue to be in the future. Among the wastes that contain copper, one of the most complex recycling materials is electronic scrap like printed circuit boards (PCB), which generally contain 10-30% copper as well as plastics, fibreglass and other metals. There are two ways to recover copper, either pyrometallurgical or hydrometallurgical. Hydrometallurgical treatments generally have more flexibilities in the process scale and control. The separation processes tend to become complicated because of the poor selectivity during the leaching in the sulphuric and hydrochloric acid media. On the other hand, the use of ammonia as a complexing agent, gave a higher selectivity for copper leaching (Nigo, Majima, Hirato, Awakura, & Iwai, 1993; Majima, Nigo, Hirato, Awakura, & Iwai, 1993; Zhou, Shinme, & Anezaki, 1995; Koyama, Tanaka, & Lee, 2006) .In this study, recycling process containing leaching, copper deposition at a cathode and oxidation of copper(I) at an anode from ammoniacal alkaline solutions containing Cu(I) or Cu(II) is introduced. Furthermore, copper recovery from a waste printed circuit boards and impurity behaviour was examined in ammonia-ammonium sulfate (sulfate system) and ammonia-ammonium chloride (chloride system) systems."

Jan 1, 2012

By G. S. Hume

Introduction Core drilling of the bituminous sands of northern Alberta has been carried on by the Mines and Geology Branch, Department of Mines and Resources, under the supervision of the Director, W. B. Timm. This was part of the Dominion Government&apos;s wartime investigations, which included an agreement with Abasand Oils, Limited, for the study of commercial possibilities of obtaining oil from the bituminous sands. The drilling programme, commenced in 1942 by the Consolidated Mining and Smelting Company of Canada, was continued in 1943 and subsequently by Boyles Bros. under contract with the Mines and Geology Branch. Several areas have been investigated and one of these, the Mildred-Ruth Lakes area, &apos; herein described, is of special importance in that it contains a sufficiently rich and large deposit of bituminous sands and bitumen beds to warrant consideration of commercial developments for the production of oil. The Steepbank Area, East Side of Athabaska River The Steepbank area, on the east side of Athabaska river in township 92, about twenty-two miles north of Fort McMurray, was selected for drilling in 1942 because previous investigations by Ells indicated it was one of considerable promise both from the standpoint of having reasonably rich bituminous sands under relatively light overburden and also having an excellent tailing disposal and plant site for large-scale operations in proximity to Athabaska river. The drilling done in 1942 and 1943 was largely exploratory, and, when it was found that the southerly part of township 92 had only low-grade material, closer drilling was done in 1944-45 in the richer, more northerly part.

Jan 1, 1947

By J. McCreedy

"The addition of Portland cement to hydraulic sand fill has resulted in the production of stable and self-supporting cemented sand fill. The use of cemented fill in the mines of The International Nickel Company has resulted in substantial economies in timber requirements, de-creased dilution of ore and greater flexibility in mining methods.Coupled with special mining techniques, it has permit-ted mining by both cut-and-fill and shrinkage stoping methods to much greater depths than heretofore. The use of cemented sand fill has permitted revisions to undercut-and-fill mining which have significantly improved the efficiency of this method.Automated mixing systems have been developed for preparing cemented sand fill in surface sand plants on a continuous throughput basis. Control of cement-sand mixtures is obtained by the use of a mass flow measuring system and weighing cement feeders."

Jan 1, 1966

By Hang Zhao, Xinping Li, Pingan Wu, Yi Luo

"The deep-buried rock surrounding the Jinping II Hydro-power Station was taken as the engineering background. Using model specimens of classified rock materials to simulate fractured rock mass under high in-situ stress conditions, the test about acoustic propagation law on single fracture model of specimen under different pressures and different angles were carried out. The variation of p-wave velocity in fractured rock mass and axial stress-strain relationship in the whole test procedure was also studied. Based on damage mechanics principle and the acoustic wave propagation in cracked rock mass, comparative study on damage constitutive relation of fractured rock mass under high in-situ stress in consideration of equivalent strain and equivalent energy was performed. As the results showed, with the change of axial stress level under constant confining pressure, the change in wave velocity can be divided into three stages: slow increase (small variation in amplitude), rapid reduce (large variation in amplitude ) and accelerate reduction. When the confining pressure is constant, the maximum p-wave velocity and the peak strength of specimens increases with the decrease of the crack angle.When the crack angle is constant, the maximum p-wave velocity and the peak strength of specimens increases with the increase of confining pressure.It is identified that the theoretical calculation results of constitutive relation about elasto-plastic damage model containing variable wave velocity in the fractured rock mass is consistent with the model test results.Therefore,the constitutive relation can provide reasonable suggestions for engineering practice. INTRODUCTIONThere are a lot of joints and fractures in surrounding rock mass of deep-lying in the Jinping-II hydropower station, which has a great influence on the physical and mechanical properties of rocks and effects the acoustic wave propagation and attenuation law in rock. Many previous research and project examples has proved that sound propagation parameters are closely related to crack and stress condition. Thus, it has certain theoretical significance and practical application value to carry out researches on sound propagation characteristics and establish damage constitutive model of fractured rock mass which is related to sound propagation parameters."

Jan 1, 2015

By Yvon T. Maurice

Under the auspices of the Federal-Provincial Uranium Reconnaissance Program, a geochemical orientation survey was undertaken in an area of uraniferous Lower Proterozoic (Aphebian) rocks near Cape Dorset in southwest Baffin Island. The main objective of this study was to establish a methodology for a future reconnaissance geochemical program using lake samples over a 300-mile Lower Proterozoic rock belt that occurs along the southern coast of Baffin Island. Mineralogical and chemical studies of known radioactive occurrences, combined with detailed sampling of secondary environment media in the vicinity of the showings. indicate that uranium is the most significant pathfinder, despite considerable enrichment of other metals in the uraniferous rocks, Significant geochemical patterns produced by uranium in lake waters and uranium in lake sediments have been obtained, but their relative usefulness depends on the distribution of carbonate bedrock, which in turn affect the bicarbonate content of lake waters. In southern Baffin Island, because of erratic variation in lake-water alkalinity, it is recommended that both water s and sediments be sampled on a routine basis. The need for lake-water acidification to prevent depletion of soluble metal ions in samples resulting from adsorption on the walls of the containers and/or suspended solid matter is discussed briefly. The base metal potential of the area was examined in some detail and found to be significant, particularly for a Lower Proterozoic gossanous formation that occurs throughout southern Baffin Island.

Jan 1, 1977

By G. H. Long, D. H. Magnusson

THE DEFINITION of the continental margin, as considered in this paper, is in the broad sense: " ... those provinces of the continents and of the oceans which are associated with the boundary between these two first-order features of the earth" (Heezen et aL, 1959, p. 17). The provinces in the area under con-sideration are: the Continental Shelf, the Continental Slope and the Continental Rise. The Continental Shelf extends from the shoreline to the shelf break, which lies at approximately the 200-meter isobath through-out the region (except north of the Grand Banks, where the break may be defined more properly by the 400-meter isobath). The Continental Slope and Rise occur between the shelf break and the 4,000-meter isobath. (The last figure was somewhat arbitrarily selected for the purpose of this paper.) The Atlantic Continental Margin as thus defined extends along the eastern coast of Canada from the International Boundary in the Gulf of Maine northward to approximately the 60°N latitude off the coast of Labrador. The area of study amounts to at }east 500,000 square miles -an area roughly equivalent to 13 per cent of Canada's total land surface.

Jan 1, 1970

By Z. Huda

The effect of various percentages of cold-working and recrystallization on the microstructure and hardness of commercially-pure aluminum plate, has been studied. The &apos;A critical deformation for the aluminum, has been determined. Experimentation involved cold rolling and recrystallization processes followed by quantitative metallographic practice and the hardness measurements. The raw material chosen was a plate of commercial aluminum which was cold rolled to different percentage of cold-work and then recrystallized by heat treatment at 150°C. The critical deformation percentage of aluminum was computed to be around 30% of cold-worked.

Jan 1, 2007

By G. R. Sadowski

"Large subhorizontal joints have been found in the foundation excavations in basalt and granite of Brazilian Dams. Some spread for hundreds of square meters showed slickensides—polished surfaces plus striations—and laminations interpreted as related to shear displacement, what substantially reduced their shear strength and imposed special reinforcement measures against the potential sliding of overlying concrete structures. The geological characteristics of these discontinuities have raised speculations related to their origin, be it related to mechanisms of bulging, cambering or to some tectonic or primary geological event.Several geologists and engineers from the northern hemisphere including Terzaghi already showed to be concerned with their role in granite foundations while in the southern regions Brazilian authors have found similar occurrences but also affecting individual lava flows of continental flood basalts in the foundations of major dams of the Parana Basin, which they designated under the particular name of “fault-joints”. This double-standard designation is self-explanatory of the difficulties involving their origin and related geomechanical properties: faults or just shear joints?Recently, similar features were encountered in the foundations of large dam constructions in anorogenic granites inserted in the realm of the Brazilian Amazon, where some of these discontinuities exhibit features common to tectonic thrusting combined with deep tropical weathering.The evidence of preshearing along the surfaces of such fractures, also associated to products of deep weathering, reduces their geomechanical strength substantially, suggesting values of ultimate phi spanning 12 to 28°. The detection of these descontinuities during initial investigation phases continues to be a major complex task in geological risk evaluations surveys. Trenching associated to some geophysical exploration techniques, although considered to be very basic exploration techniques are still the suggested methods for their forecast and previous determination."

Jan 1, 2015

By M. Mohan Rao

A Sievert &apos; technique was used. The few determinations made on 10 per cent and 20 per cent V alloys did not show any deviations from Sieverts&apos; law up to I>N2 = 1 atmosphere. The same held true for alloys of 0.2 per cent Ti. Nitrogen absorptions in Fe-Ti alloys, containing from 0.50 to 0.77 per cent Ti at 1,600°C, follow Sieverts&apos; law at low PN2 values, but, due to the formation of a delta titanium nitride phase, deviate from this law beyond critical values of PN2? There is evidence that this phase is Ti1.1N. The behavior observed can be described by the followmg equations: Ti,.,N(o) = 1.7Ti + N K = (fT; ? % Ti)1?7 (f;;.? %~_) = 0.0020 K = fN. %~ = 0.042 &apos;\)-:>N 2 I NTRODUCTJON Nitrogen&apos;s solubility in liquid iron-vanadium alloys was investi-gated briefly by Brick and Creevy ( 1), and more extensively by Kash-yap and Parlee (2) and by Pahlke and Elliott (7). Nitrogen&apos;s solubility in liquid iron-titanium alloys

Jan 1, 1963

By A. Rousselet, H. Gilbert-Tremblay, A. Berton

"Robex Resources interrupted production at the Nampala Mine in September 2014 following throughput and gold recovery results which were below expectations during the first months of operation. After a thorough plant audit, an important brainstorming took place in order to identify an economical path to resume production. It was clearly identified that a significant investment was necessary at the concentrator prior to restarting the plant, namely the addition of a ball mill and a new elution system.The mineral processing simulation software USIM PAC was used in order to simulate the grinding circuit in design. The simulations’ outputs allowed the ball mill characteristics and the surrounding classification devices to be designed with more accuracy. Many ball mills available from second hand retailers were therefore studied in the simulated circuit. The chosen ball mill, which was in perfect condition, had the advantage of being available for rapid delivery on site.The paper first describes the ball mill sizing method in comparison with the conventional Allis Chalmers method. It then describes the phase 2 concentrator start-up (that took place in 2016) with the commissioning of the ball mill, the classification circuit, the gravity concentration, the four (4) new carbon-in-leach (CIL) tanks, and the Zadra elution system (The phase 1 start-up took place in 2014). It finally provides production data compared to expected simulation data, as commercial production was reached in January 2017.IntroductionDesigning a new concentrator or new equipment within an existing concentrator requires significant efforts to identify possible bottlenecks and their causes (i.e. limiting equipment or sectors) and accurate sizing of major equipment can have a tremendous impact on the economy of the whole project. In the presented case study, the ball mill was the critical equipment and oversizing it could have brought the Capex to a level where the project would not have gone through. Inversely, undersizing the mill could have resulted in lower production and therefore no economic viability for the project once it is in operation.During engineering studies, equipment sizing often relies on a static mass balance and one-by-one sizing of all pieces of equipment. The sizing is then left to the equipment manufacturer or in the case of mills, evaluated with empirical models mostly relying on the Bond equations (Allis Chalmers method) [Rowland and Kjos, 1978]. This methodology shows the disadvantage of not considering interaction between equipment in a mineral processing circuit, especially when recirculation occurs. Also, it has the disadvantage of not using the more advanced grinding models that include the use of the whole particle size distribution as well as phenomenological components by only using limited parameters in the ore particle size distribution (i.e. the P80). This can be explained by the lack of data that sometimes needs to be gathered in order to tune the more advanced models but also by the conservative mindset in mineral concentration engineering which does not always favor the use of process simulation. In many aspects of process engineering, Soutex has demonstrated its affinity to using simulation in order to size equipment with more accuracy, consider process variability, simulate complex systems, and study supply chain management (Berton et al., 2015)."

Jan 1, 2018