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By I. Zh. Bunin, G. K. Khachatryan, N. E. Anashkina

For optimization of diamond processing technology the influence of nanosecond high voltage pulses on mechanical and technological properties of diamond crystals and kimberlite rock-forming minerals (calcite, olivine, serpentine) was investigated. Using methods of Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), microscopy and mikrohardness measurement the changes of structural, physic-chemical surface properties, and microhardness of minerals as the result of impacts, was studied. Non-thermal impacts caused a decrease of kimberlite rock-forming minerals microhardness in general to 40-66% as the result of surface microstructure destruction which is caused by formation of micro cracks, traces of surface breakdown and other defects. At the same time, the pulse energy impact on natural diamonds led to formation of B2 type crystal lattice microsift defects, elevated concentration of which increases the hardness properties of crystals. The obtained result indicates possibility of applying pulsed energy effects to improve the softening efficiency of diamond-bearing kimberlites rock-forming minerals without damaging the diamond crystals and ensuring their preservation by the subsequent grinding of ores. By IR and X-ray photoelectron spectroscopy revealed that processing by hight voltage pulses causes a change of natural and synthetic diamonds surface functional cover composition. Short-term exposure (~ 10 - 30) leads to detachment and partial destruction of secondary phases mineral films on the surface of natural technical diamonds, increasing floatability and hydrophobicity of crystals. However, with increasing duration of treatment (~ 30 - 150) occurs surface hydroxylation (found by XPS for synthetic diamonds), as a result of diamond surface layer oxidation. The effect of increasing the natural diamonds flotation activity by 14% (from 47% to 61%) was experimentally established as a result of processing diamond crystals with nanosecond pulses (~ 10-50 sec), which indicates the principal possibility of using pulsed energy impacts to intensify the diamond flotation during processing diamond-bearing kimberlites.

Jan 1, 2018

By Ayumu Tokumaru, Shuji Owada, Gangfeng Liu

"Several million spent catalytic converters are disposed annually worldwideandeach containing about 0.5-1g ofplatinum and 1-2g of all the platinum group metals (PGMs), then,it is fairly significant to recover PGMs from the spent automobile catalyst. The PGMs’ recovery is a proven technology, including pyro-and hydrometallurgicalmethods, and the highestrecovery can achieve approx. 98 wt.% by acid-leaching method, but theserecyclingtechnology seems to be too highlyenergy-consuming. SincePGMs aredistributed only in coat layer in spent catalyst, it is of great significance to enrich the coat layerwith some physical methods as a pretreatment.In this paper, according to the double-deck structureof the catalyst andthe different properties of the two main compositions, alumina-ceria phase of coat layer and cordieritephase of substrate, the concentration of the coat layer was investigated by combiningthree kinds of physical separation technologies, heating-quenching, crushing and surface grinding. In the first stage, thermal stresscouldgeneratebetween the two phasesby thermal expansion difference,to producefracturesin the thinnest part of coat layerand micro-cracksin coat layerand at the interface of coat layerand cordierite substrate. The second stage of crushing, by jaw and roll crushers, could break dominantly the coat layer and the third stage of surface grinding, carried out by attritor, promoted further separation and concentration of coat layer fromthe substrate.We also improved the attritor grinding by adding a new lift-arm to the cell for achieving better mobility of sample particles in the selective surface grinding."

Jan 1, 2014

By Julian Dimitrov, Kremena Dedelyanova

"The paper presents research on hydrodynamic processes occurring at the elementary act of flotation. Discussed existing models to determine the effectiveness of conflict of bubbles with particles in vibration column flotation machine. The paper presents a disperser for a column flotation machine, in which the dispersion of the gas phase is carried out using vertical vibration with defined frequency and amplitude. The paper presents research of mechanism for the creation of air bubbles in vibratory column flotation machine. The factors influencing the increase in the duration of the bubble in the area of contact with the mineral particles are discussed. Research was carried out on the effect of frequency and amplitude of vibrations on speed of precipitation of mineral grains of different density. Formulas are derived for the parameter effect of vibrations, applicable to the design of flotation machine. The collision efficiency of the bubbles in vibratory column flotation machine is determined. The vibrations of the hydrated layer allow for cost-effective implementation of the elementary act of flotation by providing larger relative velocities at the contact point between the bubble and the solid phase. It is proposed to complement the model more accurate representation the mechanism of attachment of the particles to the bubble."

Jan 1, 2014

By Kaioeng Wang, Qi Liu, Yahui Xiang

"In the differential metal sulfide ore flotation it is desirable to replace the toxic inorganic depressants with environmentally benign chemicals. Chitosan, as a natural and non-toxic polymer, has been proven to be an efficient depressant for chalcopyrite while allowing galena to be floated by xanthate collectors. However, the poor solubility of chitosan limits its potential applications as the flotation could only be carried out at about pH 4 where chitosan is soluble. A carboxymethyl derivative of chitosan, named N-carboxymethyl chitosan (N-CMC), was synthesized by substituting the amino groups of chitosan with carboxymethyl groups. The substitution significantly improved the solubility of chitosan. The structure of N-CMC was studied and compared with chitosan via Fourier transform infrared spectroscopy (FTIR). Flotation tests were performed on single minerals and mineral mixtures (with weight ratio of 1:1) with the addition of appropriate amount of potassium ethyl xanthate (KEX) and N-CMC. The solution pH was varied from neutral to alkaline. The flotation concentrates and tailings were collected and analysed for the contents of copper and lead. FTIR measurements showed that new peaks of C=O stretching of -COOH and N-H deformation of -NH- appeared in N-CMC, which indicated that the carboxymethyl groups were introduced and the amino groups were the sites for the substitution. Flotation results indicated that N-CMC could depress either chalcopyrite or galena depending on the pH. The results were not affected by the sequence of KEX and N-CMC addition. Therefore, N-CMC is potentially useful in Cu-Pb sulfide separation following a bulk Cu-Pb flotation. The N-CMC was also found to have surface cleaning functions, and was able to remove contaminating copper ions from galena surfaces. Therefore, its application in sulfide ore flotation is expected to be more robust than the original chitosan."

Jan 1, 2014

By M. Minagawa, G. Granata, C. Tokoro, T. Kato

"In this work, we studied the mechanochemical activation of chalcopyrite by vertically stirred ball milling (VSBM) to enhance the dissolution of copper. By using x-ray diffraction (XRD) and laser diffraction particle size analysis, we investigated the effect of milling and milling conditions on particle size and phase composition of the chalcopyrite concentrate. To elucidate the efficiency of VSBM towards the mechanochemical activation of chalcopyrite, we also conducted leaching experiments in sulfuric acid-ferric sulfate media. Under all investigated milling conditions, the VSBM determined a dramatic decrease of particle size from over 100 µm of P80% up to about 13 µm. Furthermore, the XRD of the ground chalcopyrite specimens highlighted a partial oxidation of the mineral. In leaching, upon grinding by VSBM, the increase of copper extraction ranged from a minimum of +10% to a maximum of +40%, depending on the grinding conditions. In order to elucidate whether the dissolution enhancement was a consequence of the decreased particle size or of an induced mechanochemical reaction, we performed leaching experiments on activated and non-activated chalcopyrite sample having the same particle size. In addition, we determined the activation energy of leaching before and after vertically stirred ball milling. The leaching results on samples with the same particle size highlighted a greater copper extraction and higher dissolution rates upon mechanochemical activation. Whether performing grinding by VSBM or not, the leaching kinetics was found to be controlled by the chemical reaction on the surface of the chalcopyrite particle. By grinding the chalcopyrite concentrate by VSBM, the activation energy of leaching slightly decreased from 66 to 58 kJ/mol. INTRODUCTION Due to the increasing demand of copper, low grade ores and refractory minerals like chalcopyrite are expected to become the main copper source in the next years (Klauber, 2008). As a low-grade sulfide, chalcopyrite shall be processed hydrometallurgically. However, due to the formation of a protective layer of elemental sulfur during the oxidizing leaching, the dissolution of copper is slow and/or incomplete (De Bernardi and Carlesi, 2013). Therefore, the development of new technologies to enhance the extraction of copper from chalcopyrite is highly required."

Jan 1, 2018

By A. N. Zagorodnyaya, Ye. G. Bochevskaya, E. A. Sargelova, Z. S. Abisheva, A. S. Sharipova

"In Kazakhstan, there is a unique sulphide copper deposit, in the ores containing the natural isotope of osmium-187 (more than 90 %). In the pyrometallurgical processing of concentrates for the target metal, osmium is mainly sublimated, with wet cleaning of metallurgical gases (dust and gas mixture) 40 % of it together with rhenium passes into washing solutions (wash acid). On the basis of this acid, the production of ammonium perrhenate was organized at the enterprise of the RSE ""Zhezkazganredmet"" and for the first time in the world practice - the isotope of osmium-187. However, the degree of its recovery from solutions does not exceed 8 % of the amount supplied with the charge or 25 % of the amount that was received for extraction. But the bulk of it (~ 75 %) remains in the raffinate, discharged to sewage treatment plants (wastewater). The studies presented in this work are aimed at solving the problem of osmium isotope-187 extracting from wastewater, which are a potential source of increasing metal production in Kazakhstan. The aim of this work is the development and scientific justification of osmium deposition regimes from wastewater using such reagents as thiosulfate and sodium sulphide. The influence of various physicochemical factors on the precipitation of the osmium was studied and optimal conditions for its maximum transition to sediment were chosen. An original method for obtaining osmium concentrate in the presence of sodium thiosulfate with the addition of potassium iodide from a new type of wastewater - man-made ammonia solutions has been developed. These solutions were combined mother liquors of solid-phase stripping operations and dissolution of pulp of crude ammonium perrhenate. On the basis of the obtained results, a settling technology for extraction of the osmium from man-made ammonia rhenium-containing solutions was introduced at RSE ""Zhezkazganredmet"". It should be noted that the degree of extraction of osmium, depending on its concentration in solutions entering on the settlement, and taking into account the addition of sulfuric acid, will vary from 60 to 90 %. The recovery of osmium during the test period was 58 %."

Jan 1, 2018

By Gábor Mucsi, József Faitli, Imre Gombköto, Sanjay Kumar, Zoltán Molnár, Balázs Ráczkevi, Ádám Rácz

"Generally, fly ash particles are very fine (< 100 ?m), mainly spherical and glassy materials form an outer shell on it. This paper deals with the laboratory investigation of ground fly ash based geopolymer. This material can be applied in many fields, mainly in the construction industry, e.g. non-structural elements, concrete, pavements and products, containment and immobilization of toxic, hazardous and radioactive wastes, advanced structural tooling and refractory ceramics, and fire resistant composites used in buildings, etc. The preparation of fly ash using high energy density milling is presented. Systematic experimental series were carried out in order to optimize the preparation process. The particle size distribution (LPSA) and structure of fly ash (FTIR) and the uniaxial compressive strength ,the permeability and structure of geopolymer product, furthermore the rheology of geopolymer paste were investigated. The product properties were studied as a function of the fly ash fineness. As a result of the investigation the relationship between the grinding circumstances, the ground material properties and the geopolymer characteristics was identified. It was found that the above mentioned physical properties of the geopolymer strongly depend on the grinding process."

Jan 1, 2014

By T. Wang

A new kind of mixed chelate collector was prepared in order to separate gangue (mainly quartz) and iron minerals efficiently during room temperature. The collector was was composed of two chelate collectors DES and DA. Floatation tests were carried out under 28?C with mixed magnetic concentrates of Donganshan sintering plant, and optimal test conditions were obtained, in which a direct floatation was undertaken and then a close circuit reverse floatation tests ( one roughing, one cleaning, and two scavenging), and a result of Fe grade of siderite concentrate 36.49%, Fe recovery of siderite concentrate 10.65%, Fe grade of final concentrate 66.27%, Fe recovery of final concentrate 78.25%, and Fe grade of tailing 16.22% was gained. Fourier Transform Infrared (FTIR) Spectra and Zeta potential of siderite and quartz adsorbed the DES and DA collectors before and after were measured in order to analyze the reaction between the collector and minerals. Furthermore, Molecule electronegativity of DES and DA was calculated by Electronegativity Proportionality Principle (EPP). Results showed that DES molecules have five active adsorbing sites and their molecule electronegativity was stronger while DA molecules have three active adsorbing sites, which all make the mixed collector has efficiently collecting performance. Zeta potential results of Quartz and siderite showed that at pH 11.5 both kinds of particles charged negative and at this pH value the mixed collector were mainly anionic collectors which indicate that electrostatic adsorption does not exist at this situation. FTIR results showed that characteristic peaks of the mixed collector changed before and after adsorption with the minerals, which means that there exists chemical adsorption or hydrogen bonding.

Jan 1, 2014

By K. Bru, D. B. Parvaz

"Electric pulse fragmentation (EPF) is an innovative technology that uses high-voltage pulsed power (HVPP) for the selective comminution of the treated material. Highly energetic electrical pulses are used to fracture rocks at mineral grain boundaries, resulting in extensive micro-cracks and/or complete fragmentation of the processed particles depending on the applied energy. In this study, the EPF technology was applied to a low-grade schist ore containing cassiterite, in order to investigate its influence on the selectivity of the fragmentation. The impact of EPF on subsequent comminution steps was studied by combining either the EPF technology or jaw crushing (used here as conventional crushing) with subsequent impact crushing. The results confirmed the potential of the EPF treatment for a selective fragmentation of the schist ore. This gave the potential advantages of reducing the total energy consumption in the comminution circuit and of improving the recovery of cassiterite during concentration processes. INTRODUCTION The rise in the world consumption of metals combined with the depletion of most of the high-grade ore reserves leads to an increased need to process ores of lower grade, with a more complex mineralogy. To recover the valuable minerals contained in such ores, fine grinding is required, but this process has high energy requirements and leads to the production of a large amounts of fines, which can impede the performance of later concentration processes such as gravimetric separation and flotation. Addressing this issue is a major challenge for the mining industry. Selective comminution methods have the potential to significantly contribute to the profitable exploitation of these low-grade ores by generating cracks specifically at mineral grain boundaries rather than randomly as in a conventional mechanical comminution system. This allows the liberation of valuable components from the feed material without overgrinding, i.e. this prevents unnecessary size reduction of already liberated grains, which leads to a reduction in production of fines and in energy consumption. In addition, rock not fragmented by the process are usually weakened by the dense fracture network generated, which increases grindability of the rock (Wang et al., 2011)."

Jan 1, 2018

By Venkataramana Runkana, Shantanu Maheshwari

As the world reserves of high quality ores are getting depleted at a rate higher than ever, the liberation of valuable minerals from low grade ores is becoming more and more relevant and imperative. But, liberation of minerals from low grade ores requires grinding of ore to extremely fine sizes. High energy milling in a planetary ball mill is one such option where one can produce particles in the nano-meter range. Although planetary mill is employed extensively for ultrafine grinding, dynamics of grinding inside the mill is not fully understood because of the dependency of grinding kinetics on many interconnected phenomena like collisions between media, particles and wall, time dependent rheology, adsorption and desorption of dispersant, abrasion of media, agglomeration of particles, etc. It was well articulated in literature that media motion and number of media collisions have strong effect on grinding kinetics and final product size distribution. Simulations were carried out using the discrete element method (DEM) to compare the performance of a planetary mill with a ball mill, with and without lifters, in terms of impact energy and number of collisions and it was found that number of collisions is considerably high in the planetary mill. The high number of collisions might be the reason for production of ultrafine particles in the planetary mill. We have also fitted a population balance model (PBM) to experimental data from a laboratory scale planetary mill for prediction of particle size distribution. Unlike previous models, we have incorporated functional forms for the selection function and the breakage distribution function so that the number of parameters in the PBM is just five. The predicted product particle size distributions at different grinding times are in reasonably good agreement with experimental data.

Jan 1, 2014

By Lev O. Filippov, Inna V. Filippova

"Flotation of metal-organic precipitate in column is sensible to the hydrodynamic conditions determined by the diameter and the dispersion of rising bubbles. Thus, the dissipation energy in the system resulting of ratio between superficial fluid velocities (gas and feed) in the column is the main parameter for precipitate flotation in pilot or industrial scales. The suggested limiting factor is the aggregate stability under the turbulence created by the rising bubbles. The stability of precipitate is related to the structural organisation of aggregates, which determines the size distribution of particles during precipitation and flotation stages.Structural evolution of Mo precipitate and the destruction phenomenon were described by using of the various fractal dimensions. The fractal studies allow the detection of a structural scaled organisation of the precipitate flocs. The fractal dimension of the particle mass distribution Dm=1.94+/-0.15 suggests, for the floc structure, a cluster-cluster aggregation process either with restructuring or breakage phases.The destruction process, which occurs for the lowest values of the dissipation energy E (0.02 . 0.05 W/kg) was characterised by a fractal dimension Dg of size distribution. Besides, the destruction of floc produces very fine particles, and thus induces the difficulties of bubble-particle collision during the precipitate flotation in column."

Jan 1, 2003

By A. Sand

Within stamp-charged coke making a large volume of coal is compacted to one single coal cake before entering the coke oven chamber. This is done by means of several falling stampers in a stamping machine having a mold nearly of the oven?s dimensions. Producing a high quality coke also from inferior coals requires a cake density of approximately 80% of the coal density. Besides that the industrial stamp-charging process demands a minimum mechanical strength of the coal cake to move it from the stamping mold into the oven chamber without failure. Densification and the build-up of cake strength were investigated earlier in stamping tests using a micro-stamping device. The quantities derived from these tests (as e.g. cake density or porosity) represent average values for the entire cake. Statements describing the local compaction state at different heights are difficult to achieve without destructing the cake. In order to gain better insight into the densification process and the inner structure of the coal cake a computational model based on the discrete element method (DEM) has been set up using 2 and also 3-dimensional simulation software. The stamper?s position and velocity as well as the force acting on the stamper were monitored and the model?s response was compared against measurement data from laboratory stamping tests. It was possible to reproduce the force and displacement pattern of the stamper in response to the viscoelastic properties of the cake using standard DEM bonding and contact models. Furthermore, the rearrangement of particles in response to the compaction by the stamper was tracked by calculating their displacement at the point the stamper hit the coal surface. The latter can also be used as indicators of particle deformation or breakage. By defining control points at different heights the particle displacement, stress and strain rates, porosity could be studied at different heights. Keywords: coke making, coal stamping, compaction, agglomeration, DEM, simulation

Sep 1, 2012

By Jun Qiu, Ping Chen, Xianjun Lu

Nitrogen of different forms from wastewater was adsorbed by the natural bentonite and modified bentonite. The effects of adsorption conditions on the nitrogen removal were investigated. The experiment results showed that natural bentonite could easily adsorb ammonia while poorly adsorb nitrate, the organic bentonite modified by octadecyl trimethyl ammonium could effectively adsorb nitrate with the removal ratio increased from no more than 5% to 89%. Two kinds of bentonite were added together to the simulated wastewater which contained ammonia nitrogen of 15mg/L and nitrate nitrogen of 10mg/L, the dosages were 1.0g respectively. Both ammonia and nitrate had significantly decreased on conditions that the oscillation time was 1.0h and room temperature 20?. The optimum pH value for ammonia removal was 7 while for nitrate removal was above 7. The adsorption isotherm fitting results indicated that the Freundlich adsorption isotherm was the better model to describe ammonia adsorbed on the natural bentonite and the saturated adsorption capacity was 10.25mg/L, while the Langmuir isotherm could better describe the adsorption of nitrate on the organic bentonite and the saturated adsorption capacity was 14.35mg/L. Fully considering the interaction between different ions and controlling the appropriate conditions, removing nitrogen from wastewater by adsorption of bentonite is an economic and effective method.

Jan 1, 2014

Calcium sulfate whiskers are considered to be a prosperous reinforced material in application due to their high mechanical properties. But the hydration occurs easily at moist atmosphere or in aqueous solution. The surface topographies of the calcium sulfate hemihydrate whiskers and the hydrates were analyzed by on-line observation and using XRD. The results indicated the transformation of the crystal type and shape of calcium sulfate hemihydrate whiskers and the reduction of whiskers? aspect ratio. The hydration process of the calcium sulfate hemihydrate whiskers and the effective parameters were further discussed based on FT-IR measurements. The conclusions were obtained that the hydration of calcium sulfate hemihydrate whiskers can be divided into the three phases, namely, initial hemihydration phase, dehydration phase, and coarsening, dissolving and the re-formation of calcium sulfate dehydrate crystal phase. In addition, it was found that in the hydration process of calcium sulfate hemihydrate whiskers the calcium sulfate dihydrate whiskers are formed at first and then converted into the calcium sulfate dihydrate with different crystal shapes, but in the hydration of gypsum hemihydrate the gypsum dihydrate is formed without transition products. The surface active site-calcium ion which has strong trend to react with H2O, the surface ?OH and the inner channels are considered to play important roles in the hydration process of calcium sulfate hemihydrate whiskers.

Jan 1, 2014

By M. Evertsson, E. Hulthén

"In aggregate production and mining the operators are responsible for controlling and monitoring the process to maintain high plant throughput and safe operation. Operators have to make different decisions to control the process due to changed demand on the operation from both management and conditions of the process. The quality of the response and the time it takes for an operator to respond to altered demand relies on what information is available and the experience of the operator. In this work a dynamic simulation platform has been developed to be used for operator training. Models for representing production units and process control for plant simulations have been developed and implemented in MATLAB/SIMULINK to simulate time-dependent plant behavior. Stochastic and scheduled events are included using the discrete events simulation toolbox SimEvents. The human-machine interface was developed using the human-machine interface software ICONICS. The operators’ cognitive process, in interpreting the plants semantic, has been studied by observations and with informal interviews with operators. This was done to get information about the daily operation and the problems that occur in the process. By interacting with operators that experience different physical interactions with the process; more qualitative e-learning software for supporting operator training in a dynamic operator environment could be developed. The quality of the operator training environment was evaluated with a usability study that was performed with operators and others within the production."

Jan 1, 2014

By Fu Ping-Hao, Sergio Mauricio Vianna, Ewen Silvester, Emmy V. Manlapig

"Over the last 5 years, an ambitious project has been undertaken at the Julius Kruttschnitt Mineral Research Centre (JKMRC) aiming to isolate, study and, if possible, model the effect of particle size, liberation and collector adsorption density on the floatability of mineral particles. As part of this project, we have conducted highly controlled flotation test-work, combined with state-of-the-art solution and surface analytical techniques such as High Performance Liquid Chromatography (HPLC), Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) and detailed mineralogical analysis to fully characterize the flotation behavior of a natural ore.The flotation tests were undertaken using a high-grade lead-zinc ore from BHP-Billiton’s Cannington mine (Australia) in a specially designed continuously operated laboratory scale flotation rig. Solution and adsorbed collector concentrations were measured independently during the course of the flotation tests using HPLC based ex-situ techniques. Liberation studies were performed using the JKMRC Mineral Liberation Analyser (MLA) on selected size intervals of different streams to estimate the specific surface area of galena. These results were used to calculate the collector adsorption density (collector coverage) on galena particles, with the eventual aim of developing a mathematical model describing the relationship between pulp chemistry, feed mineralogy, and floatability of galena particles."

Jan 1, 2003

Opportunities to monitor and control primary grinding mill performance are strongly sought after in the mineral processing industry. Currently, limited on-line information about mill charge motion and content is available to mill operations for control purposes, leading to periods of lower throughput, instability, variable product size and accelerated mill liner and lifter wear. In response to this need, CSIRO has developed an on-line surface vibration monitor for primary grinding mills which produces data that has been shown to provide new information about the mill charge in terms of toe and shoulder position, as well as potentially key features such as the overall charge level, the distribution between rock and balls in the mill, and the impact of the charge on the mill liners and lifters. This paper outlines the key features of the on-line monitor system, particularly those relating to data transmission, data analysis, and the design of the monitor and its independent power supply. It describes the coupling of single vibration sensor data from the CSIRO on-line monitor to the actual operating conditions of a SAG mill and how the vibration response and hence mill operating conditions vary as a function of time, including during mill equipment failures such as a broken discharge grate. Opportunities for improved mill control based on the data from the on-line monitor are also discussed, as well as the implications in terms of mill processing and maintenance performance. Recently a CSIRO monitor was also installed on a ROM ball mill and analysis of the vibration sensor data from this installation is currently underway. Preliminary findings from this installation will be presented along with comparisons of generic information, such as toe position (measurement precision and operation variability) and vibration signal (intensity, sensitivity and operation variability), between this type of primary grinding mill and AG/SAG mills.

Sep 1, 2012

By L. X. Zhang

It is very important to improve the A/S of the bauxite to keep sustaining development of Chinese alumina industry. This article summarized the issues of several desilication technologies, which are named as normal flotation, reverse flotation and bi-flotation. Normal flotation has been got industrialization because of technologic advantages. The campaign experiment of reverse flotation which has principle advantage was carried out in 2004, and bi-flotation which is combined the advantages of both the normal flotation & reverse flotation has the most attractive future. The development of bauxite flotation will be focused on multi-utilization of bauxite by mineral process technology and corresponding equipment which satisfied with the flotation technology and reagent.

Jan 1, 2014

By W. P. Roux

With depletion of higher grade iron ore reserves, and the need to process finer, lower grade material; there is a need to better understand the recovery efficiency of jigging process. The use of Positron Emission Particle Tracking (PEPT) was examined as a technique, to study the motion of particles inside a laboratory batch jig. PEPT is a noninvasive method that can provide three dimensional kinetic data of a particle during jigging. Particles with different densities and sizes were traced under the same jigging parameters, to obtain a data set that can be used for the development and verification of jigging models. From the results, detailed information on the stratification rate of a particle was obtained, with adequate resolution to see particle movement through an individual pulse. Detailed data of this nature is critical for the validation of CFD and DEM models. Keywords: positron emission particle tracking, jigging, jig models

Sep 1, 2012

By D. I. Verrelli

Within the flotation community a belief has developed that some particle shapes are more ?floatable? than others. This is usually attributed to an influence of particle shape or roughness on the induction period required to achieve attachment between the particles and the air bubbles in the pulp. Up to now, such measurements have not been able to readily isolate the effect on individual flotation subprocesses. In contrast, our experimental apparatus, the CSIRO Milli-Timer, enables us to directly observe the process of particle?bubble interaction and attachment by means of a high-speed video recording, thus providing a direct measure of the induction period for attachment. To assess the influence of particle shape on induction time we used two varieties of methylated borosilicate glass particles ? spheres and angular ?frit? ? in a range of tightly-sized fractions. In doing this, we take care to account for the influence of other factors that could affect the induction time, such as the polar angle of sliding commencement, and approach velocity. These parameters are recorded as variables for each interaction, and corrected for using multiple nonlinear regression. Our results illustrate the importance of particle shape on induction period, with angular particles exhibiting induction periods that were an order of magnitude lower than those of spheres. Furthermore, the induction period was seen to decrease with increasing particle velocity, or kinetic energy on approach, but increased as the trajectory approached the limit of just grazing the bubble. Particle shape in mineral processing is a consequence chiefly of the mineral type and the type of grinding employed. The results presented herein indicate that attention should be paid to the shape of particles obtained from the grinding operation, besides particle size. Keywords: attachment, bubbles, flotation, induction period, particles, shape effects, surface roughness

Sep 1, 2012