Search Documents

By S. Goodman

Successful exploration for and exploitation of a mineral deposit requires an accurate understanding of the deposit architecture in 3D, and of the development of the mineralizing system through time, which requires a thorough comprehension of the structural framework of the deposit. The integration of geological, geophysical and geochemical datasets to arrive at a 4D structural framework is well-established and has been successfully applied by SRK Consulting in projects from deposit to regional scale. In some cases, we can go beyond this, applying the SEEBASETM technique, which utilizes a ?bottom-up? approach to basin analysis. SRK?s approach primarily relies on the interpretation of magnetic and gravity data, calibrated with many other datasets including mapped geology, topography, event histories, wells/drillholes and seismic data. The SEEBASETM model is a culmination of this data integration and is produced through an iterative process of structural interpretation and geophysical modeling, where an interpretation of basement composition and 4D structure is used to constrain depth-to-basement geophysical modeling, and the modeled depths are then used in conjunction with the structural interpretation to constrain contouring of the basement topography. The result is a rigorously calibrated, 3D view of the basement surface, which can be used to understand the basement and basin architecture, and thus serves as a predictive exploration model. This technique, which was developed for use in the petroleum industry, is now finding success as a predictive tool in mineral exploration.

May 1, 2003

By Eamonn F. Maher

Superconductivity is one of the most remarkable scientific phenomena ever investigated. It is the phenomenon whereby some materials exhibit zero resistance to the passage of an electric current when cooled to low temperatures, and requires a quantum mechanical explanation. Four Nobel prizes in physics have been awarded specifically on the subject of superconductivity, with many more enabled by superconducting technology. For example, particle beams are generated in accelerators and manipulated in ?particle beam lines? in the ?Big Physics? projects around the world eg. at CERN, Geneva, leading to major discoveries in fundamental particle physics. Similarly, at the JET Propulsion laboratory near Oxford, U.K, controlled nuclear fusion has been demonstrated, and magnetic containment of plasmas is key. In the chemical and biological sciences high field NMR spectroscopy has become indispensable for examining organic matter, revealing the mysteries of the workings of cells, genetics, and in the development of new polymers and pharmaceuticals. With all these very advanced uses for superconducting magnets, it is easy to forget that superconductivity is big business, not just a scientific curiosity. MRI (Magnetic Resonance Imaging) superconducting magnets, the key component of high resolution body scanners, use approximately half of the world?s superconducting wire ? the other half being mostly used in accelerator magnets. The MRI market is about 3 billion dollars per annum, and one MRI magnet uses 200km of wire. New applications for superconducting magnets are now appearing including ?Catheter steering?, enabling much shorter timescales for life-saving brain tumour removals and ?Functional MRI?, a whole new area in patient diagnostics. Whilst the use of low temperature superconductors (LTS) is now well established commercially in superconducting magnets and niche electronic applications, the application of LTS in electric power distribution and transport has been very limited to date. It is now more than fifteen years since the so-called High Temperature Superconductor (HTS) materials were discovered: these can be operated at liquid nitrogen temperatures rather than liquid helium temperatures. However, materials processing and scale-up issues have prevented their widespread use, and in particular the required price/performance criteria are only beginning to be reached except in certain niche markets. BSCCO (Bismuth Strontium Calcium Copper Oxide) tapes up to one km long are now readily available, and have been demonstrated in high current cables for power distribution networks, but the general consensus is that 1) it is difficult to reduce the price much further because of the silver matrix required and 2) in applications where coils are required eg. motors, generators, transformers etc the properties of BSCCO are rather poor because of the critical current dependence on magnetic field. Magnetic fields are always associated with coils and windings, and such fields are of course fundamental to the operation of all electrical machines. YBCO (Yttrium Barium Copper Oxide) however, has good characteristics in field and for the last few years there has been intensive research and development costing several tens of millions of dollars worldwide into the scale-up of production of so-called ?coated conductor?. This ?second generation? tape can be produced by any of many different film deposition techniques, with more or less success for short lengths, but as yet it is unavailable in lengths more than a few tens of metres.

Oct 1, 2003

By B. Misra, B. S: Sastry, Kollu S. Rao

"This paper reports the results of a finite element study of the geothermal heatflow into dry mine airways. For isotropic and unsteady state conditions the heatflow into mine airways is studied for a range of surface heat transfer coefficients between rock and air, and age of the airway. Dimensionless temperature gradient values are presented in tables for different values of Boit and Fourier numbers and the results are compared with Starfield tables and Gibson algorithm. It is found that Starfield tables have consistently over-predicted the G values with errors ranging from 2% to 10%. The differences between results obtained from the finite element study and the G values calculated from Gibson's approximation method are mapped. The small error values over a large range of Fourier and Biot numbers confirm the suitability of Gibson's algorithm to rapidly calculate G values for estimating the heat transfer from surrounding rock to mine air.IntroductionIn many underground mines heat is a major problem, and the provision of acceptable working conditions requires considerable expenditure on ventilation systems. The rational design and operation of these systems depend upon an understanding of the various sources of heat in the mine. The natural source, i.e. geothermal heat, contributes up to 80% of total heat added to mine air and it is difficult to analyze and predict the heat owing to a number of influencing variables. The problem of geothermal heat flow has been studied by many investigators (Goch, 1940; Starfield, 1966; Hemp, 1987; Amano et al., 1982; McPherson, 1986).The primary concern of this paper is to develop a better ready reference dimensionless transient temperature table for estimating heatflow at any stage of mine airway life."

Jan 1, 1994

By Z. Y. Ma, H. Y. Yang

The process of microwave-ultrasound assisted leaching of valuable metals from copper anode slime was proposed in this paper. Design of experiments has been used to study the effect of the main leaching parameters, such as microwave power, ultrasound power and reaction time. The central composite design (CCD) was used to predict the maximum leaching efficiency of copper, tellurium and selenium. The experimental data obtained were fitted to a second-order polynomial equation, and they also were analyzed by analysis of variance (ANOVA). The 3-D response surface plots and the contour plots were applied to determine the optimal conditions. The optimum conditions of microwave-ultrasound assisted leaching process were: microwave power 834W, ultrasonic power 638W and reaction time 403s. Under these conditions, the experimental leaching efficiency of copper, tellurium and selenium were 98.88±0.56% 98.96±0.78% and 98.57±0.67%, respectively, which agreed well with the predicted values.

Jan 1, 2014

By H. A. Gorrell, S. R. L. Harding

"The potash beds in the Saskatchewan portion of the Williston Basin occur in the upper portion of the Prairie Evaporite formation of the Devonian Elk Point Group. They represent the late stage of a major evaporitic cycle. Two other evaporitic cycles are known in overlying beds, but these apparently never reached the stage of potash salt deposition. The basin in which salt deposition took place extended from the northwestern corner of Alberta southeastward across Saskatchewan into Manitoba, North Dakota and Montana. Deposition of potash salts was apparently restricted to the southeastern portion of the evaporite basin. On a regional basis, five major stratigraphie divisions of the potash-bearing strata have been made. Locally, several of these units may be divided into correlatable sub-units. The potash-bearing strata are separated and overlain by predominantly halite layers of varying thickness. Cross sections show the regional correlation of the potash-rich zones, and maps show the present distribution of the individual potash-bearing zones and the areas of richer development for each zone. The maps tend to substantiate the interpretation of considerable subsurface solution of salt and potash beds."

Jan 1, 1967

By Changmiao Liu, Dong Dong

"Magnesite is a major mineral resource in China, whose output and export are massive and quite important to the world. Flotation performances of eight anionic collectors on magnesite were studied to find the proper ones. Micro-flotation results indicated that collectors of HOl, SDBS and AEP had outstanding flotation performances on magnesite, with the recovery ratio all reaching above 90% in a wide range of alkaline pulp. Solution chemistry calculation, Zeta potential and FTIR measurements were employed to reveal the interaction mechanism between anionic collectors and magnesite surfaces. Solution chemistry analysis indicated that the main active components of HOl, SDBS and AEP were anions and association complex anions in alkaline pulp. Magnesite surface was negatively charged in the alkaline pulp. The active sites on magnesite surface were mainly the components of MgOH-, Mg (OH)2, and MgCO3 when the pulp pH was over 8. Anionic components of HOl, SDBS and AEP reacted with Mg in magnesite surface to make the insoluble anionic salts. And the chemical adsorption was confirmed by the FTIR measurement evidences.INTRODUCTIONAs an important industrial mineral, magnesite has been widely applied in metallurgy, building materials, chemical industry, agro-pasturage and other fields (Hu et al., 2006). It is a major mineral resource in China with abundant reserves. Its output and export are massive and quite important to the world. Liaoning province is rich in magnesite, whose reserves and production both come first in China. So far the proven reserves have reached 2.91 billion tons, accounting for more than 90% of total reserves in China, and more than 25% in the world (Li et al., 2012).Magnesite ores in Liaoning province mainly contain crystalline magnesite, and the gangue minerals of quartz, dolomite, talc, tremolite, chlorite and carbonaceous materials. Some ores also contain a little pyrite, chalcopyrite, hematite and apatite. Most of the ores must be preprocessed to separate the useful parts from the large amount of gangue minerals, so that their value and industrial application can be enlarged and promoted.Flotation is commonly used to process the magnesite ores, and the conventional flotation methods include anionic and cationic flotation. In the former, gangue minerals of silicates were separated by using amine type cationic collectors. After the impurity minerals were removed, high qualified magnesite concentration could be gained. For the cationic flotation method, it had some drawbacks of lower recovery ratio and poor performance in the lower temperature pulp (Li et al., 1995)."

Jan 1, 2016

By M. Aushouri, S. H. Mansouri, N. Aminizadeh

A thermo-chemical model of the Peirce-Smith copper converter in blowing the copper stage has been developed to predict the molten temperature. The key assumption of the model was that white metal and gas phases in the converter were in thermal and chemical equilibrium. In this model, the chemical reaction of white metal and oxygen was accomplished completely. So long as sulfur existed in the bath, the generation of Cu2O was frozen. The reaction rate was considered to be constant and controlled by the reacted sulfur. The converter temperature was calculated by heat balances over time. The model was validated by a detailed comparison with measured industrial data. A good agreement was obtained. The converter temperature depended on process parameters such as oxygen efficiency, molten emissivity and oxygen enrichment.

Jan 1, 2007

By O. Mejia

"As study was undertaken to investigate the relationship between mill liner wear and grinding energy efficiency and to assess the opportunity to control mill speed to improve energy performance as mill liner wears. The study involved analysis of plant operating data and liner wear profiles over time. The operating work index was found to be an effective tool to identify the decrease of grinding efficiency along the liner service. The plant data show that the mill grinding efficiency as determined by monitoring the operating work index, and throughput decreases as liner wears. However, efficiency and throughput can be maintained by either changing the liner more frequently or by increasing the mill speed. Two scenarios for increasing mill throughput were analyzed. The first one involves changing the liner before the efficiency drops and the second one requires increasing the mill speed from 75% to 79%. Both scenarios show financial benefits that can be used in mill operations.INTRODUCTION The analysis of the mill power draw is used in this study as a key parameter for comparing mill liner profile and its effect on mill performance. Current technology and simulation software used in the mining industry do not factor in the impact of liner wear profiles in grinding efficiency and mill throughput (Toor, 2013). To address this gap, this study provides an analysis of key factors affecting mill throughput and grinding efficiency: mill speed, ball loading, and liner profiles. Several years of plant mill operating data, published research papers, and MillTraj® simulation results are used to demonstrate that face angles impact grinding efficiency and throughput and that mill speed can be used to overcome this problem. Moreover, the liner profile wear analyses clarify a mismatch between actual and estimated power draw calculations."

Jan 1, 2019

By Gary S. Anderson

Rajant Corporation is the global leader in mining communications systems implemented a vision to develop a wireless network that is rapidly deployed, self-powered and managed, for portable or fixed configurations ? Mobile, Portable, Self-Powered, Secure and High Bandwidth. The network configures itself allowing for very rapid deployment without the time delay and personnel typically required for set-up and configuration. Rajant?s proprietary technology ?InstaMesh®? is incorporated in a device called a BreadCrumb®. Rajant has filed several patent applications on its proprietary technology and has received trademark protection on its brand names. The BreadCrumb® uses technology which allows mining, military and first responders to easily establish internet connections at remote sites or situations where existing internet communications has been disrupted. The BreadCrumb® products are standards-based Wi-Fi 802.11 a/b/g compliant, ruggedized, lightweight, portable; self-meshing and the system can be established by just turning on several of the BreadCrumb® units. The Rajant Network has evolved in the ?One Network? philosophy and has been deployed by both the military and homeland defense organizations. With multiple radios, transmitting on multiple frequencies as the same time, bandwidth is doubled, the speed of the network is enhanced, management is simplified, and manageability is made easier. Rajant has partnered with world class integrators and partners, including ten CAT dealers, a world-wide mining technology company, a mining and construction software company and leading technology innovators in mining automation and operations. Recently, Rajant provided a significant network to Rio Tinto?s Iron Ore of Canada Mine in Labrador City, Newfoundland, Canada, Kennecott Utah Copper Mine, and is currently the wireless standard at Peabody Energy and several mines in Australia. These networks range from 20-250 BreadCrumbs®. The result is a meshed mobile broadband network capable of operating in a vast open pit active mining space. Simultaneous applications currently running on these BreadCrumb® networks in the mining sector consist of Caterpillar?s VIMS?s, CAESultra grade control and Aquila Drill Management Systems, Carlson Grade Control systems, Jigsaw Technologies and Modular Mining fleet management system, Ground Probe Radar, an Automatic Train Operation and various video and VoIP applications. All vendor applications have been turned off and all applications are running on Rajant?s ?One Network?.

May 1, 2010

By J. P. Mogan, E. D. Dainty

Polynuclear aromatic hydrocarbon (PAH) levels were measured in underground mines in the vicinity of diesel vehicles equipped with several types of emission control hardware. In general, the emission control devices appeared to reduce PAH levels, but the companion mutagen study suggested that the reduction might not always be beneficial. All underground PAH concentrations were below the threshold at which a significant impact on health might be expected, but recent animal exposure studies have indicated that PAHs may not be the primary hazard from chronic diesel fume exposure.

Jan 1, 1994

By Sudarshan Martins

The measurement of acoustic signals produced by a tumbling mill has been previously used to determine the operating state of the mill and correlate the variations of the sound intensity with the operating conditions of the mill. Separately, the discrete element model (DEM), a software simulation of the mill, was developed to provide insight into the operation of the mill. Presently, there has not been much work reconciling the DEM simulation of the mill with the acoustic signal. Working from basic principles of linear, time-invariant systems, agreement between an acoustic DEM simulation and the measured signal is sought. First, the impulse response function of the mill is measured. The DEM provides the forces applied to the mill shell as a function of time. A convolution of these simulated shell forces and the transfer function gives the simulated acoustic signal. This signal is compared to the measured acoustic signal, both in the time domain and the frequency domain. Finally, a discussion of the results is given.

Jan 1, 2012

By P. Chu, J. A. Finch

The formation of small bubbles in flotation is usually accomplished by the use of frothers, or sometimes is due to the presence of inorganic salts in the process water. The effective mechanism associated with the presence of these solutes is generally considered to be coalescence inhibition. However, recent work has demonstrated that the presence of frothers and salts also reduces the size of bubble at the initial formation stage. In this paper we adapt the same experimental setup to investigate the time that it takes for a bubble to form; for a known system power input, the energy to form a bubble can then be estimated from the time. The hypothesis is that the presence of frother and salt will reduce the time for a bubble to form, which can be interpreted as an added energy component being derived from the solute. Testing different types and concentrations of frothers and salts, the hypothesis is supported: the mechanical energy required to form a bubble decreases by about 10% in the presence of these solutes.

Jan 1, 2015

By I. Pérez-Rey, J. Arzúa, L. R. Alejano

"The decrease in strength with increasing rock specimen size is usually associated to the increase in the number of defects inside the specimens at small scale (centimeters) but also to the role of the rock mass structure at the rock mass scale (meters to decimeters).This matter of concern was particularly focused when determining the size of pillars in underground mines. Some formulae regarding strength of pillars have been proposed but they usually consider only the size and shape of the pillars and the strength of the intact rock. The structure tends to be overlooked or hidden behind the scale, but it is probably very relevant. For standard tunnel design, the approach by Hoek and Brown (1997), taking the structure into account in terms of the GSI, is commonly used. However, this approach does not specifically consider the size of the tunnel. Thus, a size larger than the so-called representative elementary volume is implicitly contemplated.The authors have recently performed a lab study on the effect of the structure in the strength, deformability and post-failure characteristics of granite at lab scale (NX size) extended here. This experimental program included intact and artificially jointed rock specimens. Obtained results permit to observe the changes in strength, deformability and post-failure behavior of this “small scale rock masses”, associating the role of the structure to the observed complete stress-strain response of the specimen, which can improve our understanding of the actual complete mechanical response of rock masses."

Jan 1, 2015

By B. Chareyre, H. Pourpak, L. Scholtès, E. Papachristos

"Numerical methods used to study hydraulic fracturing in low permeability rock masses need to take into account the interaction between the progressive failure mechanism of the intact rock matrix and the pre-existing natural fractures. A fully coupled hydro-mechanical 3D discrete elements model dealing with such interaction is presented here. The ultimate objective is to grasp the role of the rock-matrix failure on the propagation of the main fluid driven fracture under different stress fields and pre-existing fracture orientations. The proposed method provides the spatiotemporal distribution of the induced crack events which can be tracked during the simulations, making possible the identification of the local mechanisms leading to macro-failure in the rock matrix or reactivation of the discontinuity planes. Fluid flow inside a fracture, pressurized crack and hydro-fracking experimental tests were simulated as part of the validation process of the model and, are presented in this paper.INTRODUCTIONWith the expansion of shale gas and geothermal reservoirs exploitation, the technique of Hydraulic Fracturing (HF) has been widely used over the past years (McClure, 2012; Britt, 2012). Despite recent advances in micro-seismicity analysis or numerical modeling (Nagel et al., 2013), the way progressive failure of rocks affects the fluid flow depending on the in situ stress conditions or the rock heterogeneities is not fully controlled yet (Zoback, 2010).In this work we focused on setting up a three-dimensional discrete elements model to study fluid driven fractures propagation. The intact rock is modeled by a discrete element method (DEM) able to reproduce fracture initiation and propagation (Scholtès and Donzé, 2013, Garcia et al., 2013). The pre-existing fractures are explicitly modeled and can be individually defined or be part of a discrete fracture network (DFN) (Harthong et al., 2012). Their mechanical response is fully coupled with the fluid within a HM-DEM framework. The fluid flow and it’s interaction with the intact matrix and the pre-existing discontinuities is modeled through a Pore-scale Finite Volume (PFV) scheme specially enhanced for fractured rock modeling (Chareyre et al., 2012, Catalano et al., 2014) ."

Jan 1, 2015

This document presents estimates of future "total cash cost per ounce" and "minesite cost per tonne" that are not recognized measures under United States generally accepted accounting principles ("US GAAP"). This data may not be comparable to data presented by other gold producers. These future estimates are based upon the total cash costs per ounce and minesite costs per tonne that the Company expects to incur to mine gold at the applicable projects and do not include production costs attributableto accretion expense and other asset retirement costs, which will vary over time as each project is developed and mined. It is therefore not practicable to reconcile these forward-looking non-GAAP financial measures to the most comparable GAAP measure. A reconciliation of the Company's total cash cost per ounce and minesite cost per tonne to the most comparable financial measures calculated and presented in accordance with US GAAP for the Company's historical results of operations is set forth in the notesto the financial statements included in the Company's Annual Information Form and Annual Report on Form 20-F, for the year ended December 31, 2009, as well as the Company's other filings with the Canadian Securities Administrators and the SEC.

May 1, 2011

By Gordon A. Gross

During the last half century major steel industries of the world have become dependent on iron and manganese resources derived from siliceous ironformation sediments. More than two billion years ago vast amounts of iron and manganese were deposited in ironformation sediments on all continents and until recent years their genesis was considered to be a uniquely Precambrian phenomenon. Research work has demonstrated that the origin of the banded ironformations was related to major tectonic features and associated volcanogenic processes that were active throughout geological history. Similar sedimentary-tectonic environments are being explored on the seafloor where metalliferous sediments are forming today. Ironformations are now considered to be a major part of the stratafer group of stratiform metalliferous deposits. They developed in sedimentary basins in areas where deep tectonic fracturing intersected high thermal gradients in the earth?s crust and gave rise to profuse volcanism and the hydrothermal effusive discharge of metals in the vicinity of the volcanic centres. Concepts for the genesis and metamorphism of stratafer deposits as revised in the last half century have had a profound impact in the development of iron ore resources and have had a dramatic impact in the use of metallogenetic concepts for guiding exploration for other mineral resources. They are based on the tectonic history and stratigraphy in the sedimentary basins, the role of hydrothermal volcanogenic processes , as well as environmental and sedimentation factors which influence the deposition of silica, iron , and other metals that were emphasized in the past. Topics of special interest in the genesis of ironformation and stratafer deposits and for guiding mineral exploration are: biomediation in their sedimentation and genesis, the significance of metamorphism in the processing and beneficiation of iron ore and in the genesis of iron ore by natural enrichment processes, syngenetic concentrations of Mn, Ti, Cu. Zn, Pb, Ni, Co, REE, F, Ba, B, As, Hg, W and Au in ironformations and stratafer lithofacies, and the mobilization of gold and other elements by alkaline solutions during diagenesis of ironformation and other stratafer metalliferous sediments.

May 1, 2003

By T. Negeri, M. Boisclair, A. Bouajila

CanmetMINING has been working on process development for separation and concentration of rare earth bearing minerals from various ores. Among others, the flowsheet development for the Montviel Rare Earths/Nb deposit, located at the north end of the Abitibi region in Quebec and owned by GeoMegA Resources Inc. (GeoMegA) is now at an advanced stage. The concentrate produced by a flotation-only process at the early stage of the project accounted for higher than 90% TREO and Nb recovery in 40% mass. This concentrate was submitted to SGS Lakefield for hydrometallurgical processing. Lixiviation of the concentrate using hydrochloric acid yielded approximately 99 % REE. An overall (from ore in ground to final precipitate) REE recovery of 80% was obtained through a series of selective precipitation steps. Recently significant additional developments have been made. CanmetMINING is steadily improving the quality of concentrate produced through a simplified, more efficient flowsheet which consists of flotation, magnetic separation, and a thermal treatment procedure. The paper discusses aspects of the process that allowed obtaining 82% recovery of TREO and Nb in 16% of mass, the best result to-date.

Jan 1, 2014

By C. K. Baxter, A. Odeshi, M. Mohammadi, E. D. Cyr

"Metal additive manufacturing has been a revolutionary step in designing new complex shapes with faster and cleaner building capacity in comparison to subtractive manufacturing processes. The ability to print lightweight alloys such as aluminum has made metal 3D printing attractive to different industrial sector from aerospace to energy and bioengineering. Of particular interest in this study, are the mechanical and microstructural properties of AlSi10Mg-200°C alloys. In this project, samples were 3D-printed in horizontal direction using an EOS M290 machine by Direct Metal Laser Sintering (DMLS) technique. Uniaxial tensile tests and high strain-rate impact e tests were carried out to investigate the mechanical properties and to study the repeatability of the process. A constitutive model is developed to predict the results of the mechanical tests at varying strain rates to better understand the high strain-rate behaviour of these alloys. Using optical microscopy, features such as scan tracks and melt pools within the AlSi10Mg-200°C samples were observed, and the microstructure was observed to be homogenous. The previously listed tests were compared to the results obtained for similar cast alloy counterpart, i.e. A360.0.INTRODUCTION A relatively new way of manufacturing parts is on the increase as rapid prototyping becomes increasingly popular throughout the world. Additive manufacturing is a process which, given a 3D model, uses metallic material in powder form to build a part layer by layer until completion (Gu, Meiners, Wissenbach, & Poprawe, 2013). This way of rapid prototyping is very attractive in comparison to other possibilities because of its ability to accommodate complex design and geometries. Conventional manufacturing methods have limitations when it comes to complex geometries, but additive manufacturing allows for increased design flexibilities while maintaining a light and stable final product (Murr et al., 2012). It also allows for a reasonable cost, especially for small batch sizes that would otherwise be extremely expensive."

Jan 1, 2018

By L. Magne, M. Maldonado, R. Varela

Real-time optimization of flotation circuits demands for accurate and reliable measurements to support the decision making process. The collection zone gas holdup is an important variable in this context as integrates the effect of machine and chemical factors on the bubble size and velocity distributions. It has been demonstrated that gas holdup not only correlates with bubble surface area flux, which defines the particle collection rate and recovery in the collection zone, but also with water overflow, a variable which has been related to the froth zone recovery. Therefore, on-line gas holdup measurements provide a reliable alternative to judge efforts leading to the optimization of flotation cells and columns. Estimation of gas holdup in flotation from electrical conductivity measurements has been proposed and extensively used in lab and industrial installations. The approach is based on the application of Maxwell's model, which relates the concentration of a dispersed phase in a continuous medium to measurements of the conductivity of the liquid medium and of the mineral pulp with and without air bubbles included. These measurements require a conductivity cell which covers a representative volume of the flotation cell, and creates a homogeneous electric field throughout this volume that ideally is not affected by the conductivity of the medium. The development of such a cell in the limiting space and geometry of a laboratory flotation cell has been problematic, but a multi-electrode arrangement offers a promising alternative. Electrodes were installed in the flotation cell of a Denver unit; the results of preliminary testing are discussed with a focus on its performance in the measurement of two- and three-phase dispersion conductivity.

Jan 1, 2015

By K. J. Heale, G. G. Richards, D. J. Rioux, R. L. Stephens

Slag fuming has remained a key process for the recovery of Zn, Pb, and minor elements in the integrated flow sheet at Teck Cominco's Trail Operations for more than 75 years. Since the start-up of the KIVCETTM process and the #3 slag fuming furnace in 1997, a range of process intensification projects have been completed to improve metals recoveries and throughput based on improved process control, mechanical modifications, and, most recently, the implementation of oxygen enrichment of the blast air. This latter project, initially named 'nitrogen depletion' and now 'nitrogen oxygen performance enhancement' (NOPE), is the primary focus of this paper. NOPE reduces the amount of heat required to heat the inert nitrogen gas, and therefore more of the energy input can be used for reduction. It also frees up boiler capacity because the inert nitrogen gas does not then have to be cooled down. A dynamic METSIMTM model was developed to determine the opportunities to improve the process capacity and heat balance to both assist with justifying the project and to verify the observed furnace behaviour. Several process safety management issues were also addressed and a few key minor mechanical modifications were made to allow the project to proceed to commercial implementation at 25% blast air oxygen enrichment. Short term plant trials have confirmed the model predictions. The first three months of a long term, continuous trial showed a 6% increase in zinc fuming rate from average furnace performance despite the implementation of a KIVCETTM fluxing change to assist with minor element recovery that was expected to negatively impact the zinc fuming rate by 3 to 5%. This encouraging result is also in line with the model predictions.

Jan 1, 2008