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By Long Han, Beijing General Research Institute of Mining and Metallurgy, Yu Xie, Yunhai Zhang, Yangge Zhu, University of Science and Technology Beijing, Yanbo Shang, Xingrong Zhang

"The first-principles method was employed to study the adsorption of hydroxyl calcium (CaOH+) and hydroxyl (OH-) on hematite and quartz surfaces. The calculation results suggested that OH- preferred to interact with the active Fe sites on the hematite surface, whereas OH- adsorbed on the quartz surface by weak hydrogen bond. Though CaOH+ could easily adsorb on the hematite and quartz surfaces by the formation of Ca-O bond, the covalence formed on the quartz surface was apparently stronger than that on the hematite surface, meaning a stronger and more stable adsorption. CaOH+ adsorbed on quartz surface was mainly through the interaction of O-2p and Ca-3d states, and this interaction on hematite surface was weaker.INTRODUCTIONIron Increase and Silicon Reduction Technology (Yu & Duan, 2002) of hematite is mainly through the reverse flotation (silica is floated away from the iron concentrate). There are two ways to achieve this (Houot, 1983). One is to collect quartz by cationic collector directly; the other is to activate quartz by lime and then collect it by anionic collector. There are two main different views with respect to the mechanism of quartz activation: mono-hydroxyl compound theory (Fuerstenau, Rice & Somasundaran, 1965; Fuerstenau & Palmer, 1976) and surface hydroxyl precipitation theory (Hu & Wang, 1988; Wang & Hu, 1990). The former indicated the formation of the mono-hydroxyl complex is one of the two criteria of quartz flotation. The later theory, on the other hand, suggested that surface precipitation is the adsorption of active species of metallic ion on quartz surface. However, most of those researches are based on the solution chemistry of flotation and little is done at the microscopic level.In this paper, by the help of first-principles calculations, the adsorption models, bonding conditions, Mulliken charge populations and adsorption energies of hydroxyl and calcium hydroxyl ions (OH- and CaOH+) on hematite (001) and quartz (100) surfaces were investigated to find out the lime activation of quartz at atomic level, which is significant for the researches of quartz activation theoretically and practically."

Jan 1, 2016

By S. H. Schulz

100 YEARS AGO, on the first of August, 1877, the mining engineer Friedrich Koepe was granted the patent rights for a hoist driving ropes on the principle of friction. It was named after him: the Koepe hoist. On the occasion of this centenary, the main features of the Kcepe principle are described.

Jan 1, 1977

By M. Staite

This paper analyzed the feasibility of converting a 5kW natural gas SOFC power generator system designed to operate on natural gas to be fuelled by methanol. The analysis included laboratory methanol fuel processing experimentation, methanol reformate SOFC cell testing, and SOFC system mass and energy balance modelling. Methanol fuel processing experimentation indicated that theoretical reformate compositions can be achieved for high temperature (600-900°C) methanol steam reforming. A 6% open circuit voltage decrease and a 10% peak power current density decrease between cell operation on humidified hydrogen and methanol reformate was observed. SOFC system mass and energy balance modelling indicated that a natural gas SOFC system can be converted to operate on methanol fuel with minimal (1%) efficiency impacts, however the systems' thermal integration can be impacted.

Jan 1, 2005

By L. Dufourm

This paper presents a review of plant layout considerations incorporated into recent designs of SAG/Ball mill circuits for two medium sized concentrators. The plant layouts presented and the design concepts discussed, relate to smaller SAG circuits, but can equally apply to larger milling circuits. Included are design concepts and ideas introduced by the various project teams, and the focus is on the primary factors of any layout design which are safety, constructability, operability, and capital cost.

Jan 1, 2012

By Z. I. Zaki

Synthesis of TiC /A1203 Composite from TiO2, Al and graphite using combustion technique has been investigated at different initial temperatures; room, 400 and 600 °C. The effect of initial temperature on the composition of the product, wave velocity and combustion temperature of the reaction was studied. The measured combustion temperature and wave velocity were increased with increasing the initial temperature of the combustion reaction. The maximum wave velocity obtained was 5.9mms-1 when conducting the combustion reaction at initial temperature of 600 °C. Oxidation resistance of the obtained composite was also studied at the temperature range 300-800 °C. No oxidation is detected before 400 °C while it takes place effectively at 700 °C forming different titanium oxides. Wave velocity measurements method was used to calculate the activation energy of the reaction between the starting materials. It was found to be 316.34 kJ mol 1 at the temperature range that was studied.

Jan 1, 2007

By M. Mirnezami, J. A. Finch, M. S. Hashemi A.

This study examined the effects of pH and sulphate concentration on the surface charge and stability of alumina and pyrite dispersions. The relationship between these properties was investigated using measurements of electrophoretic mobility and settling velocity. The maximum aggregation for both minerals was observed near the iso-electric point (iep) where the force of repulsion is at a minimum. Aggregation decreased at pH values away from the iep, where an increased surface charge causes electrostatic repulsion between particles. Zeta potential data revealed that sulphate ions were adsorbed only on positively charged surfaces for both minerals. Adsorption of sulphates on the alumina surface increased aggregation by reducing the surface charge from >+25 mV to close to zero. These results indicate an electrostatic bonding of sulphate ions to alumina surface. Preliminary results on the interaction of pyrite and sulphate ions indicate a similar response.

Jan 1, 2004

By A. Bendada, P. Servais, X. P. Maldague, C. Ibarra-Castanedo, C. Mohr

Infrared (IR) thermography is a nondestructive, non-contact and non-intrusive technique that allows the fast inspection of large and complex structures with limited accessibility. Pulsed thermography is particularly interesting for the inspection of aerospace materials such as composites given that, after submitting the specimen surface to a thermal front, the most common types of subsurface discontinuities (e.g. porosity, de laminations, dis bonds, fiber breakage and inclusions) can be detected with an IR camera as regions showing abnormal temperature patterns. We present first the case of an aircraft door with water ingress and surface repairs on its honey comb structure. We also highlight the advantages and limitations of thermography for the inspection of aircraft composite parts, such as edge flaps, rotor blades and speed breaks. Finally, we expose some results from a Kevlar® non-planar specimen with Teflon® inclusions at different depths and locations.

Jan 1, 2006

The steam-filtration process for dewatering solids involves the application of slightly superheated steam to a filter cake during filtration. The mechanism by which the technique promotes water removal has been deduced from bench-scale experiments on coal and on granular iron ore concentrates. The mechanism, along with some of the applications and limitations of the process, is presented. Introduction I N the steam-filtration process, slightly super-heated steam is applied to the filter cake during filtration to remove more water than can be extracted by conventional filtration. Although this process was developed by Burton for coal filtration (1), it should have far wider applicability; certainly, it could be used to treat any mineral product, because only low-temperature steam is needed and most conventional filtration equipment can be easily adapted to it. As few restrictions apply to this process, however, it is important that its more obvious advantages and disadvantages be appreciated and, especially, that the criteria on which economic evaluations can be based are understood.

Jan 1, 1965

By W. H. White, A. J. Sinclair

"Unaltered biotites from three samples of monzonite and gabbro from the Copper Mountain stock and a single sample from a pegmatic biotite-chalcopyrite vein cutting the Triassic Wolf Creek formation have a mean K-A age of 193±7 m.y. These data support a suggestion based on geological evidence that Copper Mountain ore deposits are related genetically to the Copper Mountain stock.A cogenetic mineral pair (biotite and clinopyroxene) from a sample of sericitized and chloritized monzonite of the Copper Mountain stock have identical K-A ages of 150 m.y., which probably represents a time of wide-spread, post-ore, hydrothermal alteration. This alteration is believed to be related genetically to a group of post-ore intrusions known as the ""mine dykes,"" suggesting that they also have an age of 150 m.y."

Jan 1, 1968

By M. Alvarez-Silva, A. Uribe-Salas, J. A. Finch, M. Mimezami

The point of zero charge (PZC) of electrokinetically anisotropic minerals (chlorite and serpentine) was determined using the Mular-Roberts (M-R) titration technique, and compared to isoelectric point (IEP) obtained from electrophoretic mobility measurements. To validate the M-R technique, the point of zero charge and isoelectric point of two isotropic minerals (alumina and silica) were shown to be comparable. For serpentine and chlorite, respectively the PZC was found at pH 4.3 and 4.6, while the IEP occurred at pH 3.2 and <3. Settling tests showed that the maximum settling rate, which corresponds to aggregated particles, for chlorite was around pH 3, i.e., close to the IEP; lizardite did not show a conclusive maximum.

Jan 1, 2009

By Zhang. L.

Ordered intermetallic PtSb had been synthesized by arc-melted and then sintering treatment. The electro-oxidation of formic acid on PtSb was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results are compared to those at a polycrystalline platinum electrode surface. It was found that PtSb intermetallic was catalytically more active than pure platinum according to the onset potential and current density. XRD and XPS technologies had been used to investigate the crystal structure and electron effect. We think formic acid decomposition on PtSb favors the reactive intermediate route and is not very much affected by the CO intermediate as compared to Pt.

Jan 1, 2005

By G. J. McTeer, D. L. Verhelst, D. J. Rioux

Teck Metals Ltd. operates an integrated zinc-lead complex at Trail, British Columbia, Canada. Since 1997, KIVCETTM flash smelting technology has been utilized for the treatment of zinc plant residues and lead concentrates. Trail Operations’ furnace uses four water-cooled jackets for bullion tapping. This paper provides an overview of KIVCET bullion tapping for the past 16 years, and discusses successes and challenges encountered with respect to operations, training and monitoring.

Jan 1, 2015

By S. Shairp

At the Hudbay zinc pressure leach plant, filtration and washing of the second stage leach slurry takes place on a vacuum belt filter prior to disposal to tailings. Due to periods of poor filterability, laboratory studies were undertaken to investigate the effect of temperature of the filter feed slurry, and to compare filterability to the resulting cake particle size distribution.

Jan 1, 2014

By Kenneth Blower

This paper gives a detailed coverage of the ore flow through the primary crusher, cobbing plant and concentrator, including equipment sizes, recoveries, reagent consumptions and product descriptions. Special features, such as rubber chutes, rubber-lined mills, pebble-mill grinding, steam-hooded filters and process control instrumentation, are also discussed.

Jan 1, 1968

By O. Lashkari, A. Charette, R. Ghomashchi

Conventional casting at low pouring temperature was employed to produce semisolid metal, SSM, billets of A356 Alloy. The deformation behavior of the as-cast SSM billets was studied using parallel plate compression viscometry. The compression tests were carried out at different applied pressures, and fractions solid. The rheological studies were conducted assuming the SSM slurry behaving like Newtonian and non Newtonian fluids respectively. The calculated viscosity numbers confirmed pseudoplastic behavior of the SSM billets and were correlated to fraction solid and shear rate proposing the following empirical equation which is valid at low shear rates, less than 0.01 s-1, and fraction solid of0.33-0.46: 0 log77 =5.56-l.38fs -(l.56fs +0.14)logy Aluminium 2006 45th Annual Conference of Metallurgists ofCIM Montreal, Quebec, Canada Edited by G. Dufour, F. Paray and J. Tessier 0.33<fs<0.46

Jan 1, 2006

The influence of joint orientation and joint persistence, on the mechanical behaviour of jointed rock masses under uniaxial compression, has been studied systematically. The joint inclination angle ß was varied from 0° to 90° with an increment of 15°. The joint continuity factor k was taken as 0.2, 0.4, 0.6 and 0.8. The peak strength, Young’s modulus, the complete axial stress-axial strain curves, the cracking process and the characteristic of the fragments, were investigated. It was found that the anisotropic response of the jointed specimens was governed by the micro-mechanism, such as crack initiation, propagation and coalescence, crack opening or closing, and frictional slip of cracks or joints. With the increase of joint continuity factor, the axial stress-axial strain curves change from single-peak to multipeak, the peak strength and Young’s modulus decrease. The specimens with medium joint inclination angle (30°,45° and 60°) has lower energy dissipation and strength due to stepped or shear failure, while specimens with small and large joint inclination angle (0°, 15°, 75° and 90°) has higher energy dissipation and strength due to axial cleavage or crushing failure.

Jan 1, 2015

By I. Imris

The chemical industries are using different type of catalysts, which after application usually produced many tons heap of residues. One of them is cupric oxide catalyst with high content of copper and silica. The recovery of copper from the waste has become major interest from a viewpoint of environmental protection and recycling of resources. The thermodynamic analysis and experimental results suggest that the copper from cupric oxide catalyst can be extracted by plasma reduction process. By plasma reduction process the inert slag and copper with following chemical composition: 99.04 % Cu, 0,042 % Fe could be obtained.

Jan 1, 2007

By Z. Huda

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

Jan 1, 2007

By R. A. Payant, J. A. Finch

Under certain conditions of air and moisture, sulphide materials can spontaneously heat, or selfheat. The reaction mechanisms of self-heating are not well understood. Most previous work has involved pyrrhotite because it is the most reactive sulphide. The current work investigates the self-heating behavior of sulphide mixtures composed of sulphides other than pyrrhotite. The four studied sulphides were pyrite, chalcopyrite, sphalerite and galena. The rest-potential was measured for each. Binary mixtures formed as a 1 : 1 weight ratio were pyrite-galena, chalcopyrite-galena, pyrite-chalcopyrite and chalcopyrite-pyrite. The four sulphides and the binary mixtures were subjected to standard self-heating tests. The four individual sulphides did not self-heat. However, mixtures of pyrite-galena and chalcopyrite-galena with rest-potential difference (?E) >0.3 volts did self-heat while the mixtures of pyrite-chalcopyrite and chalcopyritesphalerite with rest-potential differences (?E) = 0.1 volts did not self-heat. The results demonstrate that when certain non self-heating sulphides are combined they can self-heat. A possible explanation based on galvanic interaction and formation of hydrogen sulphide as an intermediate product is discussed.

Jan 1, 2009

By E. Nurminen

Thermal transport properties of copper flash smelting flue dust have been investigated. Such values of the dust are needed to correctly model the process and to optimize its heat recovery performance. Dust accretions on heat recovery boiler walls may have a significant influence on the boilers heat transfer efficiency. Measurements of the thermal transport properties have been made for industrial flue dust and for pure sulphate components. The measurements have been conducted at temperatures up to 400 °C and the effect of porosity on these properties has also been investigated. The results indicate that the flue dust and the sulphate components are effective thermal insulators and the dust build-up on the boiler walls is likely to greatly decrease the heat transfer efficiency of the boiler.

Jan 1, 2007