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By N. Dobrin, R. Sheinman, Y. V. Kokotov, L. N. Braginsky

Increasing the production of a Mixer-Settler unit requires either increasing flow rates or increasing extractant concentration. The mixers still have to ensure complete emulsification and to maintain high values of specific interface surface area in order to provide a high rate of mass transfer. Theoretically, an increase in mixing intensity can support increased flow rates without reducing extraction efficiency. Unfortunately, conventional pump mixers and mixing systems create small droplets that do not separate easily. As pumping action and mixing intensities are increased, the quantity of small droplets increases. We describe the development and industrial application of a novel mixing system for efficient mass transfer without forming significant quantities of small droplets, targeting both high mass transfer rate and low entrainment values.

Jan 1, 2014

By Michel Épiney, COREM, Mario Drapeau, Caroline Olsen, Claude Bolduc, Benoit Levasseur

"Several metal sulfide minerals (such as copper, zinc and iron), generally abundant in precious metal-containing ores, are known to dissolve during the cyanidation process. These unwanted reactions consume a significant amount of cyanide and oxygen, which is required for the extraction of gold and silver. Leaching kinetics of sulfide minerals are very fast in contact with oxygenated cyanide solutions. Therefore, the solution quickly becomes charged with oxidation products that are mostly metal ions, metallo-cyanide complexes, metal oxides and other sulfur species including thiocyanate, sulfides, polysulfides, thiosulfate, sulfites, sulfates, etc. COREM’s Extractive Metallurgy team has been conducting a research program on the improvement of the gold cyanidation process. As a part of this program, the current study aims to investigate the effect of certain operating parameters on the reactions involved during pre-oxidation and cyanidation. The effect of pre-treatment under ozone was investigated using an industrial pulp recreated from process water (charged with thiocyanates) and homogenized flotation tailings material from Agnico Eagle's LaRonde mine. In terms of mechanisms, the ozone treatment provides a complete deactivation of the material surface (characterized by EDTA extraction) and the solution (characterized by Ionic chromatography). This resulted in a lower reactivity of sulfide minerals that led to substantial gains in terms of consumption of cyanide and thiocyanate formation during the cyanidation process. The ozone-pre-treatment edges the classical pre-oxidation treatment (such as oxygen, hydrogen peroxides, etc) providing a quicker deactivation of the sulfide matrix and higher reagent savings in subsequent cyanidation process.INTRODUCTIONThe presence of sulfur in the process of gold leaching by cyanidation is a major drawback to optimizing the reagents consumption with suitable operating conditions. The coexistence of sulfide mineral species, such as pyrite, chalcopyrite, pyrrhotite or sphalerite along with the gold-bearing ore have, indeed, a negative impact on the extraction of precious metals by cyanidation (Bayat et al., 2003), (Azizi et al., 2010). These minerals are known to dissolve with cyanide under alkaline conditions and release in the slurry different kinds of sulfide by-products like polysulfides, thiosel, sulfite and sulfate (Seal II & Hammarstrom, 2003) (Breuer et al., 2008a), (Marsden & House, 2006) (Ghasemian Langeroudi et al., 2013). Once these sulfide by-products are released in solution they react with cyanide to form thiocyanate (Marsden & House, 2006) (Breuer et al., 2008b). The consequence of the dissolution of these cyanicides, is a significant increase in cyanide consumtpion as well as a slow-down of gold extraction."

Jan 1, 2016

By Rodnei Graça, Jorge Silva Bettencourt, Lena Virgínia Soares Monteiro, Baruch Spiro, Tolentino Flávio De Oliveira

Abstract - The Vazante Mine is located in the Vazante District, the largest zinc district in Brazil. The Vazante deposit consists dominantly of an unusual willemitic ore. Small sulfide bodies are tectonically imbricated with the willemitic ore, within the Vazante shear zone. Structural styles of deformation and petrographic and isotopic evidence indicate that willemitic mineralization and deformation occurred synchronously during the Neo-Proterozoic. Various generations of hydrothermal veins and hydraulic breccias may pre-date, accompany and overprint the mineralization. Ore-formation temperatures are deduced from stable isotope geothermometry and mineral chemistry of both sulfide bodies and willemitic ore. Temperatures during the main stage of mineralization range from 206°C to 294°C (willemitic ore) and 317°C (sulfides), and reflect the prevailing metamorphic conditions within the shear zone. The fluid from which the gangue minerals of the sulfide bodies precipitated (at 250°C) had an oxygen isotopic average value of ?18O = +19.4‰. This value appears to reflect the interaction of metamorphic fluid with the carbonate rocks of the Vazante formation. At 250°C, the fluid in equilibrium with the vein mineral phases and willemitic ore assemblage exhibits a uniform oxygen isotopic composition, with an average value of ?18O = +11.5‰. The positive linear covariance of ?18O and ?13C ratios of the carbonates is most likely due to the mixing of metamorphic and meteoric fluids. The ?34S values of sulfides indicate a direct crustal origin for the sulfur. It is suggested that the sulfur is largely derived from pre-existing sulfide bodies and has been transported by metamorphic fluids. The willemitic ore may have originated from the precipitation of metal in sulfur- poor fluids under oxidized conditions, within the Vazante shear zone.

Jan 1, 1999

By J. H. Shillabeer

"Rational exploration requires the prior selection of areas possessing excellent geological potential and minimum hazards to commercial development . Within an over-all strategy of grass-roots exploration, two procedures for selecting areas for (i) coal and (ii) metals exploration are described. The procedures explicitly balance infrastructure requirements and environmental concerns for areas of geological merit not alienated in parks and reserves. Through consensus, priorities are attached to those areas meriting closer scrutiny and field reconnaissance.IntroductionMining companies need to know that having made a potentially economic discovery, they will be allowed to develop it with minimum delay and at reasonable cost. The environment for exploration in British Columbia is complex and recent experience suggests that conditions are not becoming any easier. Conflicts over land use issues, preservation and economic development are common. The high cost of exploration requires that the risks should be offset where possible by: (i) carefully selecting the areas in which to work (ii) conducting operations in a responsible manner, and (iii) working cooperatively with the community of interests. This paper concerns the first action: prior selection of areas.To aid exploration planning at Suncor, a procedure was developed to grade those areas of the province possessing favourable geology according to the ease with which a mine might be developed . This had to be done within the constraints of the company's over-all approach to exploration. This emphasizes ""grass-roots"" exploration of self-generated projects in British Columbia. In addition, having selected a favourable belt of rocks, it is intended to persevere there while steadily adding to the accumulated data base and local experience. Hence, it is intended to concentrate on an area. This implies a long-term commitment to an area which in turn increases the importance of the original selection.Suncor's search is directed to finding base and precious metals in intrusive and volcanic environments, and export quality coal."

Jan 1, 1985

By R. C. Wallace

Introduction At a time when the mineral-bearing areas in Manitoba are being fi very keenly explored because of the major developments which are now taking place in that Province, it may be timely to give an analysis of the mineralization in the two major types of deposits, with a view particularly to assist in the intensive prospecting to which the mineral-bearing areas in the Province are now to be subjected. As is already well known, there are two principal types of mineral deposits in the territory- copper-zinc and gold; and attention will be confined almost exclusively in this paper to these two types, with some indication of such modifications of the main types as may be found to be of economic value. The details of the paper are drawn from what is yet a small part of the area of the Province available for prospecting. Enough is now known of the types of mineral deposits which are described in the following pages to justify the expectation that these types may serve as criteria in the search in the newer districts. Doubtless new types will also be found as investigations proceed.

Jan 1, 1928

By I. Lackey

In 2004, Zinifex Budel Zink commenced testing with the objective to increase the precipitation of aluminium in the iron purification stage of its hydrometallurgical zinc circuit, without the use of expensive reagents. Findings from the literature applied to the leach circuit at Zinifex Budel Zink demonstrated that aluminium removal from the leach circuit could be increased by lowering the ferric concentration and acidity in the vessels where jarosite precipitation occurs. An associated increase in copper precipitation was mitigated by limiting the extent to which the ferric concentration was lowered in the vessels where jarosite forms and lowering the ratio of copper to aluminium in the solutions entering these vessels.

Jan 1, 2006

By H. Z. Liu, J. M. Zhao, F. C. Wang

"Novel silicate-alginate composite beads containing 2-ethylhexyl phosphonic acid mono-2- ethylhexyl ester (P507) were synthesized and applied for the adsorption of Nd3+ from aqueous solutions. The adsorption amount of Nd3+ has been increased owing to the introduction of P507. The effect of equilibrium pH (pHe), the kinetic and isotherm experiments were investigated. The adsorption reaches equilibrium at 9 h and the maximum uptake capacity is up to 195.4 mg/(g dry adsorbent). The Langmuir isotherm equations are used to describe the adsorption process. Complete desorption can be realized with 0.2 M HCl within 20 min. INTRODUCTIONRare earth elements (REEs) have found various applications in different domains, such as metallurgy industry, ceramic industry, nuclear fuel control, photo-electro-magnetic functional materials owing to their unique properties. Neodymium (Nd), as a representative of all of the most valuable REEs, is widely used as catalysts, laser crystals, capacitors, rubber additives, Nd-Fe-B magnets, hydrogen storage and so on. Thus, the separation and purification of neodymium is significant. Unfortunately, Nd always coexists with other REEs and selective separation of the individual Nd from the REEs mixtures is still extremely difficult owing to their strictly similar atomic structures and chemical properties.Liquid-liquid extraction (LLE) and solid-liquid adsorption (SLA) are the most widely adopted techniques for the separation of REEs in the hydrometallurgical fields. The LLE process is well suited for large-scale continuous operation because of its inherent high capacity and fast kinetics. Nowadays, as a commercial extractant, 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507) has been extensively studied for extraction and separation of REEs since it has considerably good extractability and high separation efficiency (Xu et al., 1992). SLA is one of the effective and green separation methods with some prominent advantages, such as easy regeneration of adsorbents, small footprint size, less industrial wastes, higher enrichment factors and column efficiency,rapid solid–liquid separation without emulsion and so on. Hence, the introduction of extractants with excellent performance into adsorbents will integrate the advantages of LLE and SLA (Lee et al., 2009)."

Jan 1, 2012

By Masatsugu Morimitsu

This paper introduces new technology of oxygen evolution anodes which can be applied to produce copper, zinc, cobalt, and other metals by electrowinning. The anode consists of nano iridium oxide particles dispersed in amorphous tantalum oxide matrix as a catalytic layer formed on a titanium substrate. The anode can reduce oxygen evolution potential by 0.25 to 0.55 V compared to commercially available lead alloy anodes and can suppress unwanted side reactions such as manganese oxyhydroxide, lead oxide, cobalt oxyhydroxide which occur during oxygen evolution in the electrowinning solutions. This technology is effective for environmentally friendly electrowinning processes with low energy consumption and less anodic deposition.

Jan 1, 2011

By J. I. Gazzarri

A model of solid oxide fuel cell AC impedance behaviour has been developed and is used to simulate the frequency response of a single cell with and without mechanical damage. The results indicate that the presence of mechanically induced damage within the components of a solid oxide fuel cell can be detected by comparing the frequency response of the undamaged cell with that of a cell in which in-plane cracking or delamination has occurred. The presence of such defects manifests itself as a new semicircle in the Nyquist impedance diagram of the full cell. A parametric study reveals the resolution capabilities of the method in terms of the geometrical characteristics of the defects.

Jan 1, 2005

By Imane Benhamed, Jaouher Diouani, Laurent Cassayre, Florent Bourgeois, Carine Julcour-Lebigue, Université de Carthage

The attrition-leaching process aims at improving leaching performance when formation of passivation layers at the surface of leached particles is a severe limiting factor, as discussed recently by Julcour and coworkers (Julcour et al., 2015). This paper proposes a geochemistry-based modelling scheme for deriving the window of possible operating conditions for the attrition-leaching process to match the properties of the processed ore. The rationale is that the attrition-leaching process maintains the surface of reacting particles in an unpassivated state by continuous mechanical removal of surface leach layers, so that the process reactions can be modelled from thermodynamic equilibria throughout the duration of the process. The strength of the proposed modelling approach is that it bridges the gap between the properties of the ore and the process operating conditions. The present paper exemplifies the proposed process modelling route for derivation of the attrition-leaching process operating conditions in the context of the leaching of silicate ores, matching model predictions against controlled laboratory experiments. It is shown how thermodynamic modelling, when used in conjunction with a solid knowledge of the phases present in the system, can assist with deciding upon suitable process operating conditions. As an example, this firstprinciple modelling approach predicted that steel grinding medium would be converted into siderite (FeCO3) under a wide range of operating conditions, which led to questioning this initial choice of grinding medium for the attrition-leaching process under mineral carbonation conditions. It is emphasised that the same approach could be applied to ores of greater economic significance.

Jan 1, 2016

By Ian Rozier

"Emphasis in recent years in western Canada has been placed on the development of large open-pit coal mines, the most notable developments being in northeast British Columbia. However, vast resources exist below the limit of economic open-pit mining, and with world demand predictions of the late seventies in mind, the potential of underground coal mining in western Canada has been investigated. Particular emphasis has been placed on the Plains coalfield of Alberta, and there is optimism that underground coal mines will be developed in the Lethbridge area of southern Alberta.With no existing operations in southern Alberta with which to compare mining conditions, any mine planning and feasibility level studies rely heavily on the engineering/geotechnical data obtained from surface investigation to predict ground control problems and technical constraints on mining. Such investigations have been integrated with exploration drilling programs. Emphasis has been placed on extracting maximum information to provide an over-all appreciation of potential ground conditions and to identify specific ground control problems that could be encountered.The acquired geotechnical parameters are then used to evaluate the mine properties from an engineering standpoint for input into the determination of optimum mine layouts, development directions, mining methods and roadway and face support requirements. These geotechnical studies have been primarily directed toward the longwall mining method, but the acquired data base could equally be applied to alternative mining methods.In addition to the lithologic and structural controls which relate to roof stability, caving characteristics, floor heave and subsidence, investigations have been directed at gaining an understanding of the over-all surface and ground water regime with respect to potential inflow into the mine openings and ground control problems that could be caused by inflows encountered during mining. Experience has shown that soft floor conditions and water control are important factors to be considered in a longwall layout, and without doubt these parameters will play a major role in the design and operation of a successful longwall operation in the Lethbridge coalfield."

Jan 1, 1986

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 Roger M. Nendick

"IntroductionThe stages of development for bringing a mill into production demand that a flowsheet for the process be developed at an early stage. Detailed engineering of the mill may then proceed without duplication of engineering effort on alternative processes. In the case of gold and silver mills, several process alternatives exist which must be evaluated before the flowsheet is finally fixed. The recently developed Carbon-in-Pulp process has added to this choice.Clearly, the major factor in determining the most suitable process is the amenability of the particular ore to a given treatment. Other factors that will also influence the choice are location, climate, power and water supplies, and available capital.Gold and silver milling processes can be divided into three main types:Gravity Concentration;Flotation;Cyanidation.Combinations of the three are frequently used; i.e. flotation followed by cyanidation of the concentrate, or gravity concentration in the grinding circuit with cyanidation of the classifier overflow. The following are the salient advantages and disadvantages of the three main alternatives.Gravity ConcentrationGravity concentration is suitable for free-milling gold ores, i.e. ores in which the gold is relatively coarse and free from sulphides. It should be noted that just because an ore is high grade, it is not necessarily free milling.Gravity concentration methods include jigs, shaking tables, spirals and more recently Reichert cone concentrators. All methods exploit the density difference between gold, which has a specific gravity greater than 15, depending on how it is alloyed, and the gangue, which usually has a specific gravity range of 2.7 to 3.5.A concentrate grade of several hundred ounces per ton might be produced, but recoveries by gravity alone are generally low in comparison to other methods. For this reason, gravity circuits are usually used in combination with flotation or cyanidation circuits."

Jan 1, 1983

By A. W. Chan

"An interactive computer simulation model of conveyor systems used in oil sands mining has been developed to aid in the selection of mining equipment and the evaluation of operating policies. The materials handling links between supply points, such as bucket-wheel excavators and draglines, and demand points such as bins and extraction plants are modelled in such a way that the conveyor model can be interfaced with any combination of these equipment submodels. Detailed calculations of the power demand of each conveyor section based on operating characteristics and conveyor design parameters are included to permit the close monitoring of energy requirements. Various interactive features are incorporated so that an operator can not only monitor, but also control, the mining operations in the model and experiment with different operating strategies.IntroductionThe interactive simulation model of conveyor systems described in this paper is one of a number of detailed computer models being jointly developed by the National Research Council and Canstar Oil Sands Ltd. on the mining equipment and operations used in oil sands mining. Reference I presents an overview of this whole series of models, their interrelationships and the underlying motivation for their development.A network of conveyors constitutes one of the practical ways for transporting mined material in an oil sands plant. The materials handling links between supply points, such as bucket-wheel excavators, bucket-wheel reclaimers and bins, and demand points such as dumps, bins and extraction plants can be represented by a series of interconnected conveyor sections. For example, the fluctuations of the feed rate at the bucket-wheel excavator, the flow of ore material through the conveyor network and the arrival of this material at the extraction plant can be simulated."

Jan 1, 1982

By Francois Charette

Corrosion is a significant factor affecting the capacity and working life of ground support. The paper explores a relatively simple method to predict the load capacity of a support system using a Monte Carlo stochastic approach. The analysis uses published field data on existing ground support to evaluate the applicability of the method and its predictive performance. Discussion on corrosion rates found in the field and predicted from laboratory measurement is provided.

Jun 1, 2012

By P. C. Richards

"Future Integrated Gasification Combined Cycle (IGCC) power plants will have superior environmental performance and unmatched efficiency.The Shell Coal Gasification Process (SCGP) is a clean coal technology, which can convert a wide range of coals into clean syngas for high efficiency electricity generation in an IGCC plant. SCGP flexibility has been demonstrated for feeds ranging from bituminous coals to lignites and petroleum coke, and the process is ideally suited for combined cycle power generation, resulting in efficiencies of 42% to 46% (LHV).In the Netherlands, a 250 MWe coal gasification combined cycle plant based on Shell technology is being built by Demkolec, a development partnership of the Dutch Electricity Generating Board (N. V. Sep). The plant is scheduled to start up in 1993. IntroductionBasic ConceptShell's experience with gasification dates back to the 1950s, when the first Shell Gasification Process was commissioned with oil as feedstock. There are now over 140 SGP gasifiers licensed. The experience gained on oil gasification provided a firm theoretical and practical base for the start of coal gasification process development in 1972.At that time, there were serious concerns about the future availability and price of crude oil. Coal gasification (making carbon monoxide and hydrogen by the partial oxidation of coal) was considered to be an important option for refinery applications, because the synthesis gas (syngas) produced can be used as:• a chemical feedstock for making transportation fuels and chemicals;• a source of hydrogen (making use of the water gas shift reaction) for upgrading petroleum products; and• a fuel for heating process streams and/or generating electricity."

Jan 1, 1994

By D. S. Flett, A. V. Tolstov, M. A. Mulagaleeva, N. V. Gudkova, A. M. Zhizhaev, V. I. Kuzmin, Institute of Chemistry and Chemical Technology SB RAS, O. A. Logutenko, V. N. Kuzmina

The complex niobium-rare earth pyrochlore-monazite-crandallite ores of the Tomtor deposit, located in the Siberian Arctic, should be considered as a new type of rare metal materials. The major valuable components of the ore are niobium, rare earth elements, yttrium, and scandium; associated components are titanium, vanadium, aluminum, and phosphorus. Because of the irregular distribution of the rare earth metals and niobium according to grain-size, the extremely finely dispersed nature of the minerals and their close interpenetration to each other, ore processing by gravitation and flotation is not successful. The processes studied for the treatment of the Tomtor ores use direct alkaline-acid leaching to open the ore. A problem in the first stage of alkaline leaching is the high aluminum content, which decreases the activity of sodium hydroxide and alkaline-earth metals, which are bound to phosphorus. Ore processing using alkaline-nitrate and alkaline-chloride leaching was proposed and investigated. The first variant was used to obtain rare earth and scandium materials and a niobium-titanium concentrate, which can be a stock material for processors who use chlorination for the processing of ores and concentrates. The second variant is a complex advanced ore processing scheme with electrochemical regeneration of the waste chloride solutions obtaining sodium hydroxide, hydrochloric acid, and chloridizing agents. Moreover trisodium phosphate is used for purification of the waste mother liquors from metal cations. The complex salt, NaAlCl4, is proposed as the chloridizing agent for the decomposition of the niobium-titanium concentrate.

Jan 1, 2016

By L. R. Bower

"This paper describes a highly versatile variable speed unit with a torque multiplication feature as a direct replacement for a fluid coupling .The unit is comprised of a modulating clutch with torque converter and lock-up options.The UCD does not start or stop the motor. This is carried out in the normal manner.The UCD continually monitors and rapidly regulates the output speed to the requirement of a set point demand from input signals or a pre-set program with full manual override.The pre-set program can include start and stop ramps, top speed and minimum speed regulation and also mid-speed set point with security for man-riding, etc. Speed variation is from zero to 100% on a constant duty basis.The input signals can be from any source, e.g. belt weigher. load profile bunker probes, mine monitoring system, etc.The UCD when fitted with a torque converter has a torque multiplication feature which automatically provides a starting torque up to two and a half times greater than the full load torque without exceeding the normal motor power levels.IntroductionIt is common practice in the mining industry to drive conveyors, whether they be belt or chain, through a transmission system incorporating a fluid coupling between the driving motor and gear-box .However, there are drawbacks and in an effort to attain a better degree of drive and control, two-speed motors - inverters cycle- converters - hydrostatic drives, etc ., have been introduced."

Jan 1, 1986

By Ö Yilmaz

In this study, the behaviour of rock mass subjected to blasting load is investigated using three dimensional finite difference numerical modelling. In the analyses, Mohr-Coulomb failure criterion has been used for the characterisation of the rock mass strength. Stresses acting on the borehole boundary have been simulated by an exponential function which reaches its maximum within a short time and then falls to zero value in a considerable time period. The strain rate effect on the mechanical properties of rock material has also been taken into account in the analyses. Four different explosive-rock mass combinations have been studied to investigate blast induced damage zone. It has been observed that proposed equation for the dynamic compressive strength of rock material fits very well to general suggestions. Results have shown that blast damage analysis model recommended with this study is successful.

Aug 1, 2013

By Lawrence Devon Smith

"This paper examines the impact of the various assumptions that go into an economic evaluation, and shows how these can be combined to show an exciting result that may not really exist. An example of an embellished case (the kind that one frequently sees when projects are being promoted) is developed and the cumulative impact is analysed to show the actual project underneath. The paper also points out some areas to watch for overly optimistic assumptions such as prices, inflation, and debt. The concept of a ""bare bones"" base case is proposed (constant metal prices, constant dollars, no inflation, no debt, no interest, on a project basis, after tax) as a common reference point.As well, the discount rate is examined as a fundamental means of reflecting risk in discounted cash flow evaluations. Current industry practice is discussed, and a methodology for the analysis of risk levels is proposed that assesses the constituent components of the discount rate: real interest, mineral project risks, and country risk.INTRODUCTIONOften, the first time that all of the technical and economic data for a mineral project comes together in one place is when the economic evaluation is developed. This typically happens when work on the project has progressed to a sufficient level of detail that the effort to produce a year-by-year cash flow is justified, usually at the pre-feasibility or feasibility study stage. The data involved will include:• production; tonnes waste and ore mined, ore grade, mining recovery, metallurgical recovery, metal sold• revenue; metal price, smelting & refining charges, marketing costs• operating Costs; mining, milling, administration, fees, royalties• capital Costs; exploration, development, construction, indirect costs (engineering, management), contingencies, start-up, inventories, working capital, replacement and sustaining capital, closure costs• taxes and royalties• exclusions; depreciation (this is not a cash item), sunk costs (only costs going forward)."

Jan 1, 2003