Search Documents

By K. Murase

Potentiostatic electrodeposition behavior of dendritic copper from acidic copper(I) chloride (cuprous chloride) baths containing sodium chloride and sodium bromide was investigated. The morphology, or appearance, of copper dendrite and the sodium content in the dendrite as an impurity were both influenced by deposition potential (0 to ?150 mV vs. SHE) and bath temperature (R.T. to 60 C), while the current efficiency for the deposition was 99% or more irrespective of the deposition conditions examined. The bath pH did not affect the deposition behavior in the pH range of 0 to 2. Bath temperature was found to be the most important factor influencing the deposition current. The current density of the dendrite deposition on a titanium cathode was lower than that onto a copper cathode with the same substrate surface area. The reproducibility of the current for the dendrite deposition was poorer when an as-polished titanium cathode was used, although it was improved by surface treatment of the cathode with an HF-HNO3-H3PO4 solution before electrodeposition. The deposition behaviors were discussed with the potential-pH diagram of the Cu-Cl-H2O system.

Jan 1, 2007

"In 2000 the CIM Council approved the CIM Standards on Mineral Resources and Reserves – Definitions and Guidelines, developed by the CIM Standing Committee on Reserve Definitions. The Definition Standards established definitions and guidelines for the reporting of exploration information, mineral resources and mineral reserves in Canada. The Mineral Resource and Mineral Reserve definitions are incorporated, by reference, in National Instrument 43-101, Standards of Disclosure for Mineral Projects, which came into force in Canada in February 2001 and was amended in December 2005.CIM DEFINITION STANDARDS- For Mineral Resources and Mineral ReservesPrepared by the CIM Standing Committee on Reserve DefinitionsAdopted by CIM Council on December 11, 2005FOREWORDCIM Council, on August 20, 2000, approved the ""CIM Standards on Mineral Resources andReserves - Definitions and Guidelines,"" developed by the CIM Standing Committee on ReserveDefinitions. The CIM Definition Standards on Mineral Resources and Reserves (CIM DefinitionStandards) establish definitions and guidelines for the reporting of exploration information,mineral resources and mineral reserves in Canada. The Mineral Resource and Mineral Reservedefinitions were incorporated, by reference, in National Instrument 43-101 - Standards ofDisclosure for Mineral Projects (NI 43-101), which became effective February 1, 2001.At the August 20, 2000 Council meeting a new CIM Standing Committee on ReserveDefinitions was established consisting of the following: John Postle, Bernie Haystead, LarryCochrane, Normand Champigny, Mike Hoffman, Colin McKenny, Jack Mullins, Phil Olson,Fred Payne, Jody Todd and Joe Ringwald.Subsequent to the publishing of the August 20, 2000 CIM Standards on Mineral Resourcesand Reserves, various CIM committees have compiled and published more extensivedocumentation on mining industry standard practices for estimating Mineral Resources andMineral Reserves. These standard practices provide more detailed guidance than that containedin the August 20, 2000 CIM Standards on Mineral Resources and Reserves. On November 14,2004 CIM Council adopted an update to the CIM Definition Standards to reflect the moredetailed guidance available and effect certain editorial changes required to maintain consistencywith current regulations. This version of the CIM Definition Standards includes further editorialchanges required to maintain compatibility with the new version of National Instrument 43-101which is expected to become law at the end of 2005. The CIM Definition Standards can beviewed on the CIM website at www.cim.org."

Jan 1, 2003

By P. Dauphin

"CANMET’s Mining and Mineral Sciences Laboratories have developed the Canadian Mining Technology Network (CMT-Net), a website to provide industry with up to date information on technologies in several areas. This paper gives background on the Mineral and Metal Processing sector, describes the steps leading to the development of the websites strategy and gives a tour of CMT-Net. IntroductionThe government of Canada is developing a strategy aimed at fostering the development of value-added activities in the area of mineral and metal processing (MMP). Natural Resources Canada (NRCan) and Industry Canada will partner in delivering on this strategy. Instrumental in defining the main thrusts of the value-added strategy was a series of consultations held across Canada with representatives of companies and organizations active in the sector. The objective of the consultations was to identify barriers to the development of activities which add value in the sector, as well as point to positive factors.Following the consultations, a discussion paper was produced, “From Mineral Resources to Manufactured Products: Towards a Value- Added Mineral and Metal Strategy for Canada” (Natural Resources Canada, 1998). The paper reviews the sector’s structure and main statistical information, lists some of the positive factors and barriers to value-added activities and defines a new partnership between industry and government that will lead to more valueadded activities. The main objective of the paper is to serve as a discussion document between stakeholders during the development of the strategy."

Jan 1, 1999

By K. Niboucha, M. Zergoug, S. Brick-Chaouch, H. Houali

"Corrosion is an electrochemical process that causes degradation and deterioration of various steel works (pipelines, drains, cisterns) whether they are buried, immersed, or not. Worldwide, we estimate that corrosion destroys a quarter of the annual production of steel at a rate of 5 tons per second. Several techniques are used to protect against corrosion. Among these processes, Cathodic protection, which is regarded as the best technique to assure the protection of steel, works against this phenomenon. This is achieved either by a system of reactive anodes, or by the technique of impressed current protection or other techniques. Before any installation of cathodic protection, a preliminary study and pre-evaluation of certain parameters must be made. In the present work, we will present an example of dimensioning of an installation of cathodic protection by imposed current of a pipeline using solar energy, where we discuss the following items:•,Evolutions of the potential as well as current along the pipeline and their respective expressions deduced from the laws known as telegraphists;•,Range of protection (potential of protection along the pipeline);•,Influence of the isolation resistance of the coating on the range of protection;•,Effect of the aging of the coating and its influence on the current of protection."

Jan 1, 2005

By D. McConchie

The use of Bauxsol? (physically and chemically modified alumina refinery residues) to treat acid rock drainage (ARD), and sulphidic waste rock and tailings, provides new options for managing some intractable environmental problems at both derelict and active mine sites. Treatment of ARD waters using the Bauxsol technology shows that the effectiveness of raw Bauxsol material can be enhanced by including modest amounts of selected industrial minerals or common chemical additives. The type and amount of additive required and the amount of the blend needed to treat the water depends on the initial composition of the water and the target water quality; for some ARD waters, optimum treatment may require one or more changes in the type or amount of additive used. Maximum treatment efficiency can be achieved only when a balance is maintained between the rate of trace metal binding and the rate of change in water pH; adding treatment reagents faster than can be accommodated by the reaction kinetics will not result in more rapid water treatment. This paper presents the results for treating several ARD waters to illustrate the importance of blend selection and treatment procedure. Although treating ARD water is often necessary, this strategy treats the symptoms rather than the cause. The best permanent solution is to treat the sulphidic waste rock or tailings such that they do not continue to oxidise and produce acidic metal-rich leachates; sulphide oxidation needs to be stopped or slowed to a rate that can be accommodated by normal environmental processes. Capping lined impoundments is not a solution because all caps and linings will inevitably fail some time in the future creating a nasty surprise for some future generation. Adding lime is also less than ideal because the lime leaches from the treated material; treatment often appears to be effective for a few years and then fails. Bauxsol technology offers effective alternatives to conventional liming and capping procedures and Bauxsol blend application rates and procedures can be planned to ensure that no acidic or metal-rich water can ever escape from the site. Bauxsol can be physically mixed with the sulphidic mine wastes or it can used to form subsurface permeable reactive barriers, or both. Bauxsol treated waste rock and tailings can be immediately and effectively revegetated. In this paper we present leachate quality and plant growth rate data for several sulphidic waste rock and tailings deposits treated using the new technology.

May 1, 2003

By D. Mu

A method is presented for evaluating the effective gas diffusion coefficient of porous media. A series of random-distributed porous solids with different porosity are generated, a solution of the gas diffusion equations inside the porous media is obtained using the finite element method (FEM), and then the effective gas diffusivities are computed. The results show that there is a percolation threshold sp, and this percolation threshold decreases with an increase in the connectivity of the pore network; the relationship between the effective diffusivity and the porosity is strongly nonlinear when the porosity £ is less than about 0.2; and is quasi linear for higher porosities. The threshold decreases with increasing the connectivity of the pore network. A formula relating the effective diffusion coefficient with porosity is proposed.

Jan 1, 2005

By Lev Filippov, Saeed Farrokhpay

"Flotation process has had less success to recover nickel from laterite ores. Nickel in laterite ores is often finely disseminated in various minerals in very fine size. Therefore, fine grinding should be used to liberate nickel containing particles. Particles resulted from fine grinding are often very fine, and recovery of such particles is generally low using conventional flotation methods. One option to overcome this problem is enhancing the particle-bubble interaction by increasing the particle size and forming flocs. Selective flocculation of fine particle can be therefore the key to enhance the flotation performance of low grade laterite ores.INTRODUCTIONThe majority of the world’s nickel resources occur as laterite ores which are complex, low grade and expensive to treat using conventional smelting and high temperature and/or high pressure autoclave methods (Xu et al., 2013). While about 70% of the nickel resources are contained in laterites, only 40% of the world’s nickel production comes from these ores. Researchers have tried to improve the nickel laterite flotation recovery by using a number of feed preparation techniques. For example, in a study on a laterite ore sample from Australia, flotation tests on a narrow sized fraction of 38-75 µm resulted in only a small increase in the nickel content, from 1.0% to 1.4% (Quast et al., 2015a). In fact, no physical separation technique (including flotation) has been able to dramatically upgrade nickel in laterite ores (Quast et al., 2015b). Thus the challenge of processing low grade nickel laterite ores still exists. This paper aims to explore the possibility of applying selective aggregation in pre-concentrating of valuable minerals in nickel laterite ores."

Jan 1, 2016

By Shigeru Sarata

A wheel loader is one of the main loading machines in open pit mines. The authors have been conducting research and development on autonomous operation of loading by a wheel loader. The most common loading method by a wheel loader is the ?V shape? path method. The loading operation consists of cycles of scooping from the pile, traveling to the dump truck, loading on the dump truck and return traveling to the scooping point for the next cycle. The traveling path includes a switchback in the middle of the path. The moving direction of the loader is changed at the switchback point. From observation of V shape path loading operations by experienced human operators, it seems that they control the bucket position between the scooping point and loading point on a shorter path for higher productivity. A new path planning method is proposed this paper, whereby a point on the center of the tip of the bucket is controlled moving from the initial point and the final point. The motion of the controlled point is generated by the wheel steering the wheel loader. The controlled point is moved along the direction to the final point; however, the motion and mechanism of wheel loader have restrictions, such as the velocity of the loader, the steering angle, and the steering angular velocity. Because of these restrictions, the path of the controlled point is not a straight line between the initial and final points. When this control method is applied between the scooping and the dumping points directly, the planned path is not stable in the leaving wing of V shape path. Therefore, the initial position of the wheel loader is set at the switchback point, then two approach wings to the scooping and the dumping points are made. The whole planned path is obtained by connecting the two paths. The shape of the planned path is strongly affected by the position of the switchback point, as well as the scooping and the dumping points. By simulation of path planning at different switchback points with the combination of the scooping and the dumping points, the paths for more effective loading are determined. The results of the simulation are presented in the paper.

Aug 1, 2013

By Simon Houlding

"Part 1 (CIM Bulletin, August 1991) of this article identified the limitations of the traditional modelling methods and demonstrated the approximations and errors introduced by their application to complex mining situations. The objective of Part 2 is to describe the evolution of new, proven technology which eliminates these deficiencies and provides precise and practical alternatives. These promote the use of realistic geological and mining shapes and eliminate altogether the rectangular approximations of traditional methods. Limitations of the Traditional MethodsThe limitations of the traditional modelling method s (viz. simple block modelling, gridded modelling and their more recent variations) were discussed in detail in Part I . These methods are all based on the use of rectangular discretization to represent the boundaries and volumes of ore deposits and mining excavations. As a result they are unsuited to the representation of nonrectangular geological complexities such as folding, faulting and irregular surfaces . They are equally unsuited to the representation of realistic excavation limits, particularly in the case of underground mining.Recently these methods, with limited variations in technique, have been applied to increasingly more complex geological and mining situations. The resulting potentials for error and conflict within the modelling pro cess were demon strated in Part I . The effects can be summarized as follows:• volume and boundary approximations introduced by therepresentation of irregular three-dimensional boundaries andvolumes by rectangular modelling elements ; • geostatistical errors and conflicts caused by neglect of the relationships between grade estimates and the geometric/ spatial aspects of irregular volumes and associated observations (samples), including an inability to produce precise estimates with meaningful confidence limits;• a compounding of these effects by using rectangular element sizes other than the geostatistical optimum, and by using differentelement sizes within a model; and• general inefficiencies introduced throughout the modelling pro cess by the requirement to represent geology, grade distribution and excavation limits with a singular modelling method and model."

Jan 1, 1991

By Y. Héroux, A. Chagnon, M. M. Savard

"Résumé - Le gite de Pb-Zn de Gays River s'accompagne d'anomalies des propriétés de la matière organique (MO) et des assemblages de minéraux d'argile (AMA). L'association entre la minéralisation, la distribution de la réflectance de la MO et des AMA suggère que ces traceurs peuvent servir à I ‘exploration des sulfures de métaux de base dans cette région.A I ‘emplacement du gîte, la réflectance varie considérablement (0,8% à 1,88%), pouvant même afficher une baisse avec I ‘enfouissement, ce qui est interprète comme une altération chimique de la MO. Les valeurs les plus élevées s'accompagnent localement de quelques textures en mosaïque et délimitent une anomalie thermique au centre sud de la région. Parmi les minéraux des argiles identifies, I ‘illite et la chlorite sont terrigènes alors que la smectite, la kaolinite et la corrensite sont authigènes et, à l' instar de I ‘altération de la MO, résultent des nouveaux équilibres chimiques créés suite à la précipitation des sulfures.Abstract - The Gays River Pb-Zn ore deposit is associated with anomalies defmed from the characters of the organic matter (OM) and from the clay minerals assemblages. The relationships between these anomalies and the mineralization at the mine suggest that these parameters can be used as new guides for the exploration for base-metal sulfides in this area.The vitrinite reflectance (RJ shows a wide range of values (0.8% to 1.88%) and exhibits an anomalous suppressive effect with depth of burial at the mine site, suggesting a chemical alteration of the OM. The highest R"" values are associated with mosaic textures and outline a therrnal anomaly at the south-center of the studied area. Among the identified clay minerals, illite and chlorite are terrigenous, whereas smectite, kaolinite and corrensite are authigenous and, like the alteration of the OM, are due to the new chemical equilibria resulting from the precipitation of the sulfides."

Jan 1, 1994

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

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

Jan 1, 2016

By John H. McKillop

Industrial minerals production in Newfoundland in--creased in gross value by a total of 175 per cent during the ten-year period from 1954 to 1964. The Province accounts for all of ?Canada's fluorspar production and contains one of the most important fluorspar districts in North America. It is also the only producer of pyrophyllite in Canada, and quite recently has become an important producer of asbestos fibre. Limestone, gypsum, brick shale, sand and gravel also ?Contribute appreciably to the expanding industrial minerals phase of the Province's rapidly growing mining industry. Geological diversity characterizes Newfoundland's industrial minerals: Pyrophyllite deposits were formed by contact metamorphism of predominantly volcanic Proterozoic rocks. Fluorspar deposits are fissure-filling veins having the characteristics of typical epithermal deposits. Chrysotile asbestos production comes from one of the Island's serpentinized ultrabasic belts. Limestone is produced at three localities; two of them in the extensive carbonate rocks of the west coast. Gypsum production comes from a thick evaporite (gypsum and anhydrite) sequence in the Carboniferous rocks of the St. George's Bay area. Introduction

Jan 1, 1965

By B. Burke

Magnesium and its alloys are attractive materials for use in automotive and aerospace applications because of the low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. The present paper reviews the efforts to improve the attractiveness of magnesium through non-traditional processing, and presents preliminary results of current work on producing magnesium alloys via powder metallurgy P/M. P/M can be used to alleviate the formability problem through near-net-shape processing, and also allows unique chemical compositions that can lead to new alloys with novel properties. The feasibility of producing magnesium powder metallurgy products utilizing the industrially dominant process of mixed powder blending, uniaxial die compaction and controlled atmosphere sintering was investigated. An alloy composition based on the commercial Mg alloy AZ31 (3% Al, 1% Zn) was used to facilitate comparison to similar wrought products. The optimal processing conditions (compaction pressure, sintering time and temperature, and quenching temperature) were found to maximize sintered density and mechanical properties.

Jan 1, 2007

By Fernand Dubuc

"The New Pascalis property is situated in Louvicourt and Pascalis townships, about 200 km east of Val d'Or, Quebec. It is made up of 38 claims under option to SOQUEM since August I, 1981 during which time SOQUEM has earned a 60% interest. The property is underlain by archean basaltic volcanics that have been intruded along the west boundary by the Bourlamaque batholith, and by north -trending dykes.The 1982 disco very is related to the re-evaluation of a 1931-gold showing located in the southeastern part of the property, a combination of the presence of a weak IP anomaly at the eastern end of the showing and overburden stripping at that location, resulted in the discovery of a mineralized diorite dyke.The dyke, which strikes N 20 ° Wand dips vertically , has intruded E-W striking agglomerates. The dyke contains south dipping, gold-hearing quart z-tourmaline-pyrite veins that are distributed in a ladder-type arrangement. Visible gold may he observed in drill core, and is generally associated with pyrite porphyroblasts.Diamond drilling has outlined th e dyke for a strike length of 300 11/ and a width of about 10 m, Result s of this drilling indicate, to a depth of 155 m, reserves of 834 000 metric tonnes grading 8.25 g Au/t un cut or 5.38 g Au/t cut to on e ounce. However, four deeper holes have added depth extension to 400m. Also, west of the dyke and within 150 m, other promising gold values have been intersected within quartz-tourmaline veins associated with other parallel dykes."

Jan 1, 1985

By T. G. Sitharam, Resmi Sebastian

"Wave propagation studies across jointed rocks have significance in the fields of rock mechanics and geophysics. The passage of a seismic wave induces strains in rocks and often, these strains are of low magnitudes except at the vicinity of source. These low magnitude strains are generally in the elastic range and hence elastic constants necessary for the design and analysis of strength of rock mass, can be derived from wave velocities. Measurement of travel time velocities and measurement of resonance frequencies are the two methods usually adopted for obtaining wave propagation velocities.Resonant column apparatus measures wave velocities from the resonant frequencies obtained during testing. Depending on the type vibration applied, torsional or flexural, shear and compression wave velocities are secured. By varying the amplitude of vibrations applied, various strain levels can be introduced and corresponding resonant frequencies and wave velocities can be calculated. The resonant column experiments were performed on a model material, hardened Plaster of Paris (POP) samples, in laboratory. The paper explains the preparation of samples and the working mechanism of resonant column apparatus along with the estimation of wave velocity from resonant frequency. The numerical simulation of resonant column apparatus using distinct element method and its validation with the experimental results are presented in the paper.A distinct element code is usually used to simulate the movement of materials with intersecting discontinuities. Finite rotations and displacements of individual blocks representing the material are permitted and new contacts between the blocks are identified as the calculation progresses. Three dimensional Distinct Element Code (3DEC), the software intended for the numerical simulation of rock engineering projects, can well simulate the behavior of jointed rocks under static and dynamic loading conditions. The numerical simulation of resonant column apparatus has been performed with 3DEC considering its efficiency in modeling jointed rocks.The numerical modeling of the resonant column apparatus with application of torsional and flexural vibrations to the sample is elaborated in the paper. The response of samples to a range of frequencies is obtained and the frequency that induces maximum displacement in the sample is measured as the resonant frequency, for any particular strain level. The displacements measured at various points of the sample during application of vibrations are compared and presented. The numerical modeling of resonant column apparatus with an intact sample (without joint) and a sample with a joint incorporated are explained at a particular strain level. The resonant frequencies obtained from laboratory experiments and numerical simulations are compared and illustrated. It has been found that resonant frequencies obtained using numerical and laboratory experiments are in good comparison and can be extended for various strain levels and sample conditions."

Jan 1, 2015

By William C. Browning

An economic drilling programme is one which costs the !east in chemicals, equipment, and time. The basis for such a programme with rotary drilling techniques is a drilling fluid in which bentonites do not swell. This is recognized in the growing trend toward gyp and other inhibited mud systems. Therefore, even though the mechanism of thinner action is a subject of applied colloid ,chemistry, the understanding of this mechanism is of economic importance in controlling the flow properties of inhibited muds. In phosphate, or sodium tannate, conditioned muds that are relative-!y free of contaminating-electrolytes, the thinner, or dispersing agent, is adsor.bed, ?creating an electrical double layer about the clay particles. The mutual repulsion of these charged particles effects colloidal stabilization, or deflocculation of the suspended clays, as discussed by Norton and others. In inhibited muds, however, the electrolyte concentration in the filtrate is sufficient to collapse the double layer and flocculation of the mud solids occurs, as evidenced by increased viscosity and gel values. Chemicals to control the flow properties of inhibited muds, therefore, are vital to the successful use of these systems as it is not always economical to adjust flow properties by watering back. Flocculation of suspended particles, as indicated in the work of Vervey, Overbeek, and others, is due primarily to gravity-like, long-range Van der Waals forces. Prevention of flocculation may, therefore, be secured by the interposition of any barrier between the particles, the thickness of which approximates the extension of the Van der Waals at-traction. Organic polyelectrolytes, such as Kembreak, Rayf!o, and Q-Broxin, may act to increase the double layer charge when used in small amounts in fresh-water muds. More important, however, is the fact that in inhibited muds an increase in concentration of the polyelecholyte permits the formation of a condensed film adsorption layer of the polyelectrolyte about the clay particle. When this occurs, the extremely viscous condensed adsorption layer creates a mechanical. barrier that prevents flocculation of clays, even in the presence of inhibiting concentrations of elecholytes. Rheological evaluation of the degree of deflocculation, or colloidal stability, may be made by utilizing the known effects of particle inter-action and volume concentration on the flow properties of suspensions. Rheological evaluation should be supplemented by direct microscopic or ultra-microscopic observation.

Jan 1, 1958

By P. J. Finnis

This paper describes the use of wire rope on open-pit mining equipment, giving specifications and examples of the performance achieved. Installation methods are also discussed, making the paper of considerable practical use to mine operators.

Jan 1, 1973

By A. E. Gillis

"Some or all of the following benefits can be expected following application of automatic control to a grinding circuit:1. Maintenance of Optimum Mill Load Level2. Improved Uniformity of Grind3. Increased Productivity4. Decreased Power Costs per Unit of Product5, Reduced Ball Wear per Unit of Product6. Reduced Labour Costs per Unit of Product7. Reduced Operator SupervisionTo establish an indication of the benefits that could be expected through automation of the grinding circuit at East Malartic Mines Ltd. it was agreed that the Department of Mines and Milltronics Limited should jointly conduct a survey of the existing grinding circuit and operation.Aside from establishing feasibility, an important purpose of this survey was to determine costs of a suggested control system that East Malartic Mines Ltd. management might be in a position to assess the economics of the proposal and justification of the investment.The survey involved the taking of sound recordings of rod and ball mills during manual operations, locating circuit bottlenecks, establishing time constants and determining the number and location of sensors for good automatic control."

Jan 1, 1966

By N. Dahata

B206 aluminum?copper alloy has a potential for wider use in the automotive industry due to its light weight and relatively superior mechanical properties as compared to aluminum-silicon alloys. The possibility of casting this alloy via Lost Foam Casting (LFC) has not been investigated in detail. Therefore, the effects of foam types (T170B standard untreated EPS and T175-brominated EPS), coating types (Styro Shield 5553 and Styro Shield 5554), copper level (4.5 wt % and 5.0 wt %) and titanium levels (0.5 wt % and 0.25 wt %) were related to fillability, microstructure and microporosity. The metal velocity in T175 EPS pattern was higher than that in T170B EPS pattern. For T175 EPS pattern, the total solidification time was 3% higher and the loss of temperature for decomposition of EPS was lower than those in the case of T170B EPS pattern. The grain size, porosity level and maximum pore size were quantified using Light Optical Microscopy (LOM) and image analysis. The casting with T175 EPS pattern showed larger grain size relative to that with T170B EPS pattern. The porosity level and the maximum pore size decreased significantly when the titanium level was increased from 0.05 wt % to 0.25 wt %.

Jan 1, 2007

By S. Banisi, A. R. Hasankhoei, Gh. Parsapour, A. R. Ghasemi

At the Gol-E-Gohar mining and industrial Company, a pelletizing plant, which includes two parallel dry closed grinding circuits and a pellet production circuit, produces 600 t/h. Each grinding circuit consists of a burner, a dry ball mill (6 m×13 m) and an air separator. Each ball mill consists of a 2 m-long dryer chamber and an 11 m-long grinding chamber. Iron ore concentrate is fed to the drying chamber to decrease its moisture from 2.5% to below 0.2%. The drying chamber consists of 56 flights in two rows. It was found when the feed moisture content decreased from 1.3 to 3.5%, the throughput decreased by 14% (40 t/h) indicating a low performance of the dryer. In order to improve the efficiency of the drying section, a scale down version of the dryer was constructed in a 1m diameter mill with a transparent end to make image analysis possible. It was found that because of the inappropriate veiling profile in the drying section, most of materials are not subjected to the hot gas tunnel. To overcome this problem, various flights with different geometries were physically tested and also simulated by the KMPCDEM © software. With the aim of arriving at a proper veiling profile which maximizes the particles contact with hot air, a new flight design was obtained and tested. The installation of the rectangular tooth type flights in one of the mills in the plant made the comparison of the old and new designs possible. The evaluation of the designs in a period of three months indicated 15 t/h increase in the throughput in the case of the new flight design.

Jan 1, 2016