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By M. M. Papic, J. C. Whitehead

"A sample of Hat Creek coal has been extracted using supercritical aromatic solvents in a laboratory-scale extraction unit. Extract yields in the range 21 to 27 per cent of dry-ash-free coal were obtained.These yields are significantly lower than yields available from high-volatile bituminous coal and some lignites. Thus in a combined extraction/hydrocracking scheme for the production of liquid fuels from Hat Creek coal the char product would exceed that required to supply the energy and hydrogen requirements of the process. Excess char could be used for the production of power or gas for sale.IntroductionThe Supercritical Gas Extraction (SGE) process developed by the U.K. National Coal Board operates in two stages: an extraction stage in which a coal extract is separated from mineral matter and undissolved coal and a subsequent hydrogenation stage.The SGE process is based on the ability of a compressed supercritical fluid to dissolve relatively high molecular weight substrates. It is operated under conditions where a hydrogenrich portion of the coal is selectively extracted in a short residence time extraction stage leaving a hydrogen-deficient char. The process schematic shown in Figure I illustrates that the extract produced is separated from the solvent and passed to a conventional hydroprocessing stage while the char product is utilized in the production of heat, power and hydrogen for the process. An extract yield in the order of 50 per cent dry-ash- free coal represents a ""balanced"" case for such a process in which there is just sufficient char for the provision of these commodities."

Jan 1, 1985

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 L. Hanschar, C. Bwalya, E. Mokola, K. Musonda, A. Makayi

This paper describes the installation, commissioning and operation of porous plugs featuring nitrogen gas purging in both Anode Furnaces at the Kansanshi Copper Smelter (KCS), a greenfield copper smelter which commenced operation in March 2015. The decision to install porous plugs was taken in November 2016 and the facilities were successfully commissioned on both anode furnaces in October 2017. The project was successful and has demonstrated the following process improvements: 12.2% reduction in main burner fuel consumption Larger average charge size, due to fewer accretions; 17 minute decrease in average refining cycle times Improvements in slag skimming operations Improved casting rates INTRODUCTION Porous plugs The application of porous plug technology in copper smelter anode furnaces is well established around the world. Vukovic and Gamweger (2017) and Wallner (2004) noted that the stirring and mixing action induced by the injection of inert nitrogen gas into the molten copper via porous plugs has potential benefits in the following areas: Homogenization of the temperature and composition of the molten copper resulting in Reduced fuel consumption Less tendency to overheat slag (reduced risk of refractory attack) Less slag produced with a lower degree of oxidation (lower rate of refractory wear) Less tendency for buildups to form Improved environmental performance (produce low sulphur blister at Peirce Smith converters) Elimination of buildups inside the furnace and potential for larger charges per cycle Reduced processing times and potential for shorter cycle times More efficient skimming of anode slag Shorter skimming time Less copper carry over to Peirce Smith converters Very little slag remaining in the furnace (reduced potential for buildups to form)

Jan 1, 2019

By L. A. Homeniuk, R. J. McH. Clark

"The Maurice Bay deposit, the Stewart Island showing, the Fond-du-Lac deposit, the Middle Lake showing and the Nisto deposit are located on the North Rim of the Athabasca Basin. They are probably unconformity-related. These occurrences tend to be small. The Fond-du-Lac and Maurice Bay deposits are the largest and contain 450,000 kg and 650,000 kg of U10 8 respectively.Pitchblende is the main uranium mineral of all the occurrences, except at Middle Lake where autunite predominates. A II of the deposits are overlain and partially hosted by the Manitou Falls Formation of the Athabasca Group, except the Nisto deposit which is entirely within basement rocks, and the Maurice Bay deposit which is partially within the basement and overlying the Fair Point Formation of the Athabasca Group.The North Rim deposits are considered to be genetically similar to the other unconformity-type deposits found in northern Saskatchewan. It is suggested that a mechanical concentration of uranium may have occurred in heavy mineral beach sand type placers. The stability of the uranium minerals may have been enhanced by special local conditions. The fossil placers, after hydrothermal alteration and enrichment, would form the apparently ""rootless"" occurrences of uranium found totally within the sandstones above the unconformity.IntroductionAt least five deposits and showings and one train of mineralized glacial erratics of unknown provenance have been located on the North Rim of the Athabasca Basin from Maurice Bay in the west to Black Lake in the east. Distributed over a distance of 250 km, (Fig. l), they occur near the edge of the Basin, and are probably unconformity-related. The following have been identified from west to east (Fig. 2): The Maurice Bay deposit, the Stewart Island showing, the Isle Brochet train, the Fond-du-Lac deposit, the Middle Lake showing, and the Nisto deposit."

Jan 1, 1986

By A. Azad

SAGD (Steam Assisted Gravity Drainage) is an in-situ oil recovery technique for heavy oil reservoirs. The technique has been successfully applied to many projects in the past 25 years and the process has been, now, well understood. It is now believed that geomechanics plays an important role in SAGD and should be considered in numerical or analytical modeling. Currently, geomechanics is numerically modeled through combining a multi-phase flow and a geomechanical simulator. Numerical modeling is, however, time consuming, need lots of input data, and could not be used for quick decision-making purposes. To decrease the modeling time, this study based on a new version of the Reis drainage model, proposes coupled mathematical model and reserves the effect of geomechanics in the process. Results showed a perfect match with the past experimental and numerical data.

May 1, 2009

By I. Yutronic

Compañía Minera Doña Inés de Collahuasi's (CMDIC) Concentrator Plant is located at 4300 meters above sea level, approximately 2000 kms north from Santiago, Chile. The concentrator has three grinding lines. Each one, Lines 1 and 2, have one SAG mill at the primary grinding stage followed by a secondary grinding and classification stage consisting of one ball mill, two hydrocyclone batteries and a sump with two pumps. Line 3 has one SAG mill (Gearless Mill Drive), followed by a secondary grinding and classification consisting two ball mills, four hydrocyclone batteries and a sump with four pumps. Average throughput for these three lines is 150 Ktons per day. Peak values of 180 ktons per day have been achieved. Since late 2008 and throughout 2009 and 2010, Operations and Automation areas developed an optimization program for the grinding process, considering the implementation of Model Predictive Controllers (MPC) for the three SAG mills, and later, extending MPC to the secondary grinding and classification stages. The implementation of a MPC solution was based on stability considerations (high variability of the SAG process, high interaction between sump level control and classification efficiency, etc), requirements for an automated and consistent operation, the need to maximize throughput under timevarying scenarios and, in the long term, optimization of grinding process considering Specific Energy Consumption, among other parameters. MPC solutions had proven control robustness and strong optimizing capabilities in terms of helping in discovering new operational points and so achieving all of the aforementioned goals. On the first stage of the program, MPC implementation considered identification of dynamical process control models based mainly on historical data, in order to know the impact of a group of Manipulated Variables over Controlled Variables. Also, the impact of measured Disturbance Variables was modeled in order to take into account the high impact and interaction of these variables over the processes. At the end of this stage, 4 controllers were successfully operating for the 3 SAG mills and the secondary grinding and classification process. In response to challenges made by the working group, the second stage of the development of control applications in the grinding process required to achieve a design and implementation of a solution capable of governing the milling process, in addition to stabilization and optimization of both processes (SAG milling and secondary grinding), to integrate from a point of view of process control and automation. Therefore, in the second stage, MPC performance was continuously monitored and optimized through advanced tuning, inclusion of more process models (with proper step tests), redefinition of specific optimization criteria and adjustment to new process needs. Finally, successful MPC implementation at Collahuasi has proved that fast development and deployment of process control solutions is possible and allows immediate process stability, higher throughput, specific energy consumption reduction, and successful product size control, among many others.

Jan 1, 2012

By David Lewin

The journey toward cleaner coal-fired power generation is driven by technological improvements, more stringent regulations around greenhouse gas and other air emissions, and the potential of one of Canada?s most abundant resources. Within this context, EPCOR is leading efforts to commercialize gasification technology to produce electricity with near-zero emissions. By turning coal, oxygen, and water into synthesis gas through a gasification process ? and then capturing CO2 ? it is possible to dramatically reduce greenhouse gas and smog-related emissions. EPCOR is conducting front-end engineering and design work on an Integrated Gasification Combined Cycle technology (IGCC) utility-scale plant ? in conjunction with the Canadian Clean Power Coalition ? at its Genesee site, west of Edmonton. EPCOR, the Alberta Energy Research Institute, and Natural Resources Canada have each contributed $11 million to the $33 million project. A critical element of the project features the capture of CO2, which would be piped underground for long-term sequestration, or for use in enhanced oil recovery (EOR). The combination of IGCC and CO2 sequestration, at this scale, has not been used anywhere else in the world.

May 1, 2008

By Melanie Grob

Two commonly estimated fractal dimensions, called b and D values, represent statistical characteristics in the distribution of magnitude sizes (b) and spatial hypocenter locations (D) of microseismic events, respectively. We postulate that the values of b and D are related to specific stress regimes. Through different case studies of fluid injection into an oil/gas reservoir or geothermal field, we infer that the measured temporal variation in fractal dimension b is most likely due to significant changes in the local stress regime. The fracture dimension D indicates the spatial clustering of events. The distribution of these events can vary with time because of stress perturbations that (re)activate fractures whose direction favours their movement under a specific stress regime. Thus a combined statistical study of these two dimensions can help infer the variations of local stresses in a reservoir.

Jun 1, 2012

By Dr. Rory Cameron, Dr. Terry Cheng, Dr. Nadia Mykytczuk, Ian Bedard, Kristie Tarr, Ruth Joseph

Pyrrhotite-rich tailings from Sudbury, Ontario mining activities are known to contain significant amounts of EV metals, such as nickel and cobalt.  CanmetMINING has developed a novel bioleaching process for recovering the nickel and cobalt (both critical for vehicle electrification) from tailings that incorporates partial neutralization and iron removal in the bioleaching circuit; bench- and pilot-scale tests have resulted in excellent nickel and cobalt recovery over a range of temperatures.  However, this process generates a new bioleach residue, which is heavier and more voluminous than the original tailings due to pyrrhotite oxidation and jarosite formation during the bioleaching process. This residue can be problematic for long-term disposal. A possible solution being studied for this issue is using mine backfill as a disposal mechanism.  Underground backfilling allows for effective re-purposing of mine waste, however the backfill must also be able to withstand a certain load, since in most cases it is used as an underground construction material, such as in cut-and-fill mining methods.  Therefore, the composition of the mill tailings must be such that when combined with a binding agent and pumped underground, the slurry or paste is then able to withstand a certain load within a certain period of time.  Unfortunately, high-pyrrhotite content tailings, commonly found on mine sites in Ontario and Quebec, are reactive and can easily oxidize and produce acidity and/or metal-laden drainage under some disposal conditions. This means that the pyrrhotite in the tailings can lead to acid mine drainage if stored on surface, however, it can also cause strength degradation if re-purposed in too high a concentration in underground mine backfill.  The research being done at CanmetMINING related to the bioleaching process is aimed not only at recovering nickel and cobalt from mine tailings, it is also being used in an attempt to neutralize the tailings to reduce acid mine drainage and backfill strength degradation. This paper reports on research designed to evaluate different options for transforming the bioleaching process residue into iron oxide phases, for better environmental footprints if stored on surface, as well as increased disposal possible, if re-purposed as underground mine backfill material.  

May 4, 2025

By Ali Bunjaku, Lauri Pesonen, Hannu Johto

It is well known that there are many ways to process copper concentrates into copper anodes using the pyrometallurgical route. All modern copper smelting technologies are fundamentally energy efficient and environmentally safe options, and therefore choosing one depends on the desired capacity range, feed impurity levels, plant location, flexibility needs, overall energy use, and of course smelter economics in both the short and long term. This paper focuses on comparing different solutions which have potentially the lowest variable opex (operational expense), meaning in practice finding out which technology offers the best chances for profit maximization under certain scenarios. For the comparison, we chose to have a closer look at Outotec Flash Smelting (FSF) – Peirce-Smith Converting (PSC), Outotec Flash Smelting (FSF) – Outotec- Kennecott Flash Converting (FCF), Outotec Ausmelt TSL Smelting (ASF) - Peirce-Smith Converting (PSC), Outotec Ausmelt TSL Smelting (ASF) - Outotec Ausmelt TSL Converting (ACF), Mitsubishi Smelting Process (MIT), Bottom Blowing Reactor (BBR) – Bottom Blowing Continuous Converting (BCC), and Side Blowing Furnace (SBF) - Top Blowing Converting (TBC) since these seem to be the main state-of-art technologies now being applied in many recent copper smelter projects around the world. The work was carried out by modelling each smelting route by using the new HSC SIM 9 simulation software and applying operation time, energy, and consumables consumption numbers for each unit process and stream. Combined with cost data, the exercise produced a rich set of information which will be shown in detail for each area per scenario. The authors’ goal here was to provide a fair comparison where each technology can be evaluated from various perspectives such as electricity use or refractory consumption. INTRODUCTION Copper can be produced either pyrometallurgically or hydrometallurgically. The hydrometallurgical route is used only for a limited amount of the world’s copper production (~20%) and is normally only considered in connection with in-situ leaching of copper ores. On the other hand, most of the copper extraction from Cu-Fe-S minerals is pyrometallurgical (~80%) (Schlesinger 2011, ICSG 2017). Thus, several different processes can be applied for copper production, including the following state-of-the-art technologies: Outotec Flash Smelting (FSF) – Outotec-Kennecott Flash Converting (FCF) Outotec Flash Smelting (FSF) – Peirce-Smith Converting (PSC) Outotec Ausmelt TSL Smelting (ASF) - Peirce-Smith Converting (PSC) Outotec Ausmelt TSL Smelting (ASF) - Outotec Ausmelt TSL Converting (ACF) Mitsubishi Smelting Process (MIT) Bottom Blowing Reactor (BBR) – Bottom Blowing Continuous Converting (BCC) Side Blowing Furnace (SBF) - Top Blowing Converting (TBC)

Jan 1, 2019

By Dave Rose, David G. Meadows, Mike Westendorf

"Copper Mountain’s concentrator was commissioned in May 2011. The circuit consists of a 34’ x 20’ EGL SAG mill, a Raptor 900 pebble crusher and two 24’ x 39’6” ball mills. Each mill is equipped with a 2 x 8500 HP dual pinion drive system. The plant was designed to process 1585 mtph of SAG feed. From startup, the mill struggled to meet the required production rates. Over time, a major initiative that involved blasting and fragmentation, optimization of the SAG mill in terms of discharge grates, ball size and slurry density, and operation of up to three mobile pre-crushing plants resulted in significant increases in throughput. In parallel, a number of modeling tools, including JK SimMet, were run based on plant benchmarking exercises. Samples collected at the mine site during ramp up confirmed the very competent nature of the ore with drop weight - A*b values of less than 24 being recorded on a variety of plant feeds and lithologies. After due consideration including demonstration of proof of concept, a new pre-crushing circuit incorporating an XL2000 cone crusher and associated screening equipment was designed, constructed and commissioned at the site in August 2014. This paper reviews the history of the original circuit design, the various optimization steps taken and impacts, together with the final pre-crushing circuit and net results.IntroductionThe Copper Mountain Mine is located approximately 20 km south of Princeton, British Columbia, Canada (refer to Figure 1). The region has a long history of copper mining dating back to 1923. The Copper Mountain camp occurs in the 'eastern volcanic belt' of the Nicola Group (Monger, 1989). It is an alkali copper-gold deposit in which the volcanic strata are intruded by early Jurassic dykes, sills, irregular plugs and zoned plutons (Woodsworth et al., 1992). The stratified rocks are relatively fresh with slight metamorphism in the local contact regions."

Jan 1, 2016

By O. M. Arafat, J. A. Finch

"The Functional Performance Equation calculated from a plant grinding survey defines two distinct ball mill circuit efficiencies and how they relate to total production rate through the target grind size. The survey data are also used to calculate a complete ball mill size distribution model, represented by the energy specific grinding rates, not just through the target grind size, but through all the size classes. Cyclone separation performance is represented by individual size recoveries to underflow. When these two unit operation performances are entered into the circuit modelling program (Streamline™), along with the circuit feed rate and size distribution, all the circuit survey size distributions and mass flows are perfectly regenerated by the program. The many issues associated with the historical Epstein (breakage-selection) models are eliminated. Once the circuit program is populated, pump and cyclone performance changes can be evaluated using a step-by-step procedure in order to maximize Classification System Efficiency. Mill water use and media sizing opportunities are also diagnosed in order to maximize Mill Grinding Efficiency at the size of interest. An example is provided. This circuit analysis and modelling system, and related training, is provided through a web-based application.IntroductionSince its development (McIvor, 1988), the Functional Performance Equation for ball milling has facilitated new understanding of industrial circuit cause and effect relationships, leading to significant strides in operational performance. Success stories of this refreshing approach to plant circuit performance improvement are now too numerous to list. Finch and McIvor (circa 1986) also discovered that the Functional Performance “Mill Grinding Rate” at the size of interest was the same cumulative grinding rate that is calculated from mill feed and discharge size distributions using a first-order rate equation. By calculating these cumulative grinding rates for all screen sizes, a complete ball mill model is generated (as used by Finch and Ramirez, 1981). Others in industry, Hinde and Kalala (2009), for example, have noted the same. Lacking the complexity needed to maintain their interest, most researchers have ignored this model, broadly opting instead for Epstein’s (1948) characterization of grinding as a chemical reaction, combining “selection rate” and “breakage size distribution” functions. The much simpler ball mill model presented here has previously been incorporated into a proprietary circuit modeling program (McIvor, 2005) and used for plant improvement work (for example, see McIvor and Finch, 2007, and McIvor, 2014). Now, by combining this extremely business-friendly ball mill model with optimization criteria from Functional Performance Analysis, a circuit modeling system (including the needed supplementary steps to assure successful plant implementation of circuit design changes) is at the disposal of every plant metallurgist, grinding equipment/material provider, and circuit designer."

Jan 1, 2017

By K. Jomoto, H. Majima

"Experimental work has been attempted to find a useful criterion of comminution which can be determined simply in a laboratory. The suitability of the ratio of the square of tensile strength to Young's modulus, St2/E, previously derived from the theory of elasticity as a criterion of comminution, was examined measuring tensile strength, Young's modulus and critical height for drop-weight impact of five different rocks. However, satisfactory correlation between St2 /E and critical height has not been obtained, suggesting the necessity of further experimental verification of the representative value of Young's modulus of rocks. The plot of St2 vs. critical height, however, shows one-to-one correspondence, and this finding suggests that St• may be a useful criterion of impact crushing. Also, a close relationship was observed between st• and the energy index for tumbling mill grinding of •the sample rocks. It is confirmed from these findings that the quantity St• is a useful criterion of comminution of rocks, not only for impact crushing but also for tumbling mill grinding. As shown in the experimental part of this paper, the determination ol St with irregularly shaped specimens is simple."

Jan 1, 1972

By S. C. Livanou, S. P. Tampouris, E. N. Zevgolis

In ferronickel (Fe-Ni) production from oxidized nickeliferous ores, mechanical losses of ferronickel in the slag are reduced by magnetic separation. Slag from the electric furnaces (E/Fs) contains 0.16% Ni. Its magnetic separation gave a pre-concentrate with 0.76% Ni, weighing approximately 6.5% of the feed. Nickel recovery was 29.7%. This pre-concentrate was then treated in a second (concentration) plant. Concentration treatment involves screening, crushing and magnetic separation. A pre-concentrate with 0.76% Ni gave a magnetic concentrate with 2.58% Ni and a non¬magnetic part with 0.35% Ni. Smelting of the non-magnetic part without the addition of a reduction agent in a laboratory electric arc furnace, gave a ferronickel alloy with approximately 20% Ni and a slag with 0.16% Ni.

Jan 1, 2005

By S. Makni, S. Koppalkar, A. Bouajila

This paper reviews briefly the gravity recovery involving conventional gravity separators and centrifugal gravity separators. The advantages of semi-continuous gravity separators will be discussed. Techniques for upgrading the gravity concentrates will be addressed briefly. The research efforts in optimizing semi-continuous gravity separators will be recalled. Innovative gravity circuit for eliminating or minimizing the use of complex processing schemes will be reviewed. On-going gold gravity research at COREM has revealed that gold particle shape transformation is the main factor explaining the lower recoveries of the plant units. Efforts to devise possible remedies for improving gravity recovery at plant will be discussed.

Jan 1, 2011

By R. Roufail

Mineral liberation is accomplished by comminution and is the first step towards achieving successful downstream processes such as flotation or leaching. In metal mining, one of the most effective comminution methods that is used to grind particles below 10 microns is stirred milling. In this paper the study of particle breakage mode vs. mill operating parameters is addressed. Stirred mills' grinding action is mainly attrition, but operation can be manipulated to include breakage by compression or impact loading. Macro and micro analysis of particle breakage and grinding mechanisms are correlated. Macro analyses convey information that relates grinding mechanism to particle size and shape. It is speculated that the breakage mechanism in the horizontal stirred mills is massive fracture for the coarsest particles and attrition (abrasion) close to the grinding limit where the size reduction ratio approaches 1.0. For micro analysis, the particle breakage mode has a direct impact on fracture type either transgranular or intergranular. Intergranular particle breakage leads to higher mineral liberation compared to transgranular breakage. Similar minerals would have more homogeneous properties that convey a stronger bond compared to dissimilar, heterogeneous mineral bonds. Transgranular fracture requires higher energy than inter granular fracture; trans granular fracture toughness of pure single phase mineral is about 10-14 % higher than the intergranular fracture toughness. This communication presents the results of an investigation to assess how operating conditions can affect trans- vs. inter-granular breakage.

Jan 1, 2009

By H. J. Chalmers

"Since the advent of large volume flotation machines, Cominco Ltd. has actively studied possible application of such machines to their various milling operations. A number of installations have been made and more are on the drawing board. This paper gives a description of these units, information as to choice of equipment, and information as to operating experience. Mechanical and operating details of six installations are summarized. Three different types of machines are discussed.Pine PointThe original Pine Point zinc flotation circuit comprised conventional roughing with two stages of cleaning. Over the years with increase in feed tonnage there have developed two adverse conditions; namely, a reduction in zinc concentrate grade coupled with an increase in MgO in the concentrate. This resulted in higher freight payments along with more severe smelter penalties. An intensive test program, in 1971, showed that the concentrate grade could be raised by 1.5 units of zinc along with a reduction in MgO from 0.8% to 0.47.. Subsequently this was done by adding two additional stages of cleaning using 16 cells of Denver 200-V's. The project was completed in January 1973 at a cost of $510,000 to give an estimated annual savings of about $390,000.Selection of the Denver Model 200-V was based on minimum floor space requirement, availability, and favourable operational and maintenance experience with Denver 100’s. As it happens it was possible to ""shoe-horn"" the 16 cells into place with a minimum of plant alteration. Some problems have been encountered with a tendency to ""sand up"" at high pH, particularly at the corners. Otherwise operational service has been very good."

Jan 1, 1974

By X. Shi

Magnesium, the lightest structural metal, has not yet been considered as a serious contestant for automotive use due to its weaknesses in corrosion. Electroless nickel-boron alloys are well known for their corrosion resistance and hardness. An electroless nickel-boron layer was successfully deposited first on the chemical conversion pre-treated AZ31 alloy and also on the Ni-P coating which was deposited on the conversion coating. The electroless bath contained nickel sulphate and dimethylamine borane (DMAB) as main salts and the samples were activated by a 5 g/L AgNO3 solution before the electroless plating process. The presence of the conversion coating between the nickel coating and the AZ31 substrate acted as a barrier and prevented corrosion of the alloy. The morphology of the nickel-boron layer was studied using SEM. The crystal structure and the composition were examined by EDS and the hardness was measured. The corrosion behaviour of the nickel-boron layer deposited on the conversion coating and on the Ni-P coating was studied using potentiodynamic polarization in a 0.5M NaC1 solution. A saturated standard calomel electrode was used as a reference electrode. The results show that the nickel-boron coatings had a significantly better corrosion resistance than the AZ31.

Jan 1, 2006

By G. Barbery, P. Dauphin

"In order to obtain reproducible and reproducible results in batch flotation, researchers have tried various approaches, from normalized testing, to modifying existing cells, and even designing new machines. The paper reviews the basic concepts that must be fulfilled in a laboratory flotation machine, and present the FLOTOMATEC design, which results from five years of testing and development. In addition to providing accurate measurements of air flowrate, power consumption, agitation speed, the cell eliminates most operator induced errors. Results of experiments comparing FLOTOMATEC to a conventional cell, as well as reproducibility tests are given. Introduction The use of batch flotation machines in mineral processing research and development is very common. These machines have been used for many years without almost any change in their design, instrumentation or automation. Various authors since Raffinot (1960) have criticized the available designs, especially with respect to the large errors that are introduced by the manual mode of operation. Barbery et al. (1986) have presented a review of the problems involved in laboratory testing in flotation research.Batch laboratory machines should have the following characteristics:"

Jan 1, 1989

By Dave Bulled, Chris Bennett, Glenn Kosick, Glenn Dobby

"Mining companies around the world are embracing geometallurgical modeling at a rapid rate, as senior executives realize that inputs must be properly measured if the output is to be managed effectively. Geometallurgical modeling is used to scientifically manage risk in project evaluation, for plant design and production forecasting, and optimization of production planning and mineral processing/metallurgical unit operations. The technology also provides a solid foundation for implementing broad corporate strategies with respect to intelligent asset utilization and metal sales. Over the past five years, MinnovEX Technologies Inc. has been actively engaged in developing, promoting and applying geometallurgical modeling technology for major mining companies around the world. This paper describes the methodology for successfully applying the technology for the unit operations of comminution and flotation in the mining industry.INTRODUCTIONGeometallurgical modeling (referred hereon as geomet modeling), in theory, can be applied to its full potential on all unit operations in mineral processing; however, this paper will concentrate on two of the largest unit operations, namely comminution and flotation, where the technology is actually being practiced by many large mining companies. For concept studies and prefeasibility studies, aspects of geometallurgical technology are regularly applied but in a less rigorous manner than for final feasibility studies where justification for funds is sought. This paper will focus on the final feasibility stage of a project and on existing operations or planned expansions, where the full power of geometallurgical technology is brought to bear in a cost effective manner.One of the unique aspects of geomet modeling, when used to its potential, is the ability to design plants, and forecast and plan production with a quantifiable degree of precision, something that was unattainable in the past. This means that when new comminution and flotation plants are designed, the mining companies and financial institutions involved in the project can measure the precision of the design and therefore better understand and manage project risk. It means that for existing and new operations, metal sales personnel can carry out their sales strategies with a much better understanding of the degree of error associated with production forecasts of concentrate/metal and quality of concentrates. For mine and mill managers, geomet modeling allows the effect of the mine plan on the downstream processes to be quantified; thereby allowing the mine plan to be recast in a more optimized manner. Finally, existing concentrator personnel can optimize their unit operations based on a more definitive understanding"

Jan 1, 2004