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By Liu Fan, Shang Yanbo, Wang Zhongming

"Besides valuable metals of Cu, Sn, WO3, Zn, there are S, Ag, CaF2, In and so on in a complex ore deposit in south China (which belongs to Hu Nan Shizhuyuan Non-ferrous Metal Limited Liability). Although it proved reserve amounts to 3.5×107 ton, its crystal character limits its utilization in large-scale. It features complex relationships between valuable minerals, finest crystallized particle size, low-graded valuable metals (Cu 0.30%, Zn 0.5-0.7%, Sn 0.2%, W<0.1%). If only tungsten minerals are considered, it means WO3 grade is too low (the cut-off grade of WO3 is 0.1% in China). Only Cu and Sn minerals are recovered from 2006 and Cu recovery is less than 70%, Sn 15-20%. Other valuable metals of W, Zn, S and CaF2 were lost in the tailings. To make good use of the ore, the technology of fully recovering Cu, Sn, W, Zn, CaF2 and rare metals are in urgent need. After systematic researches, the flow sheet of "bulk flotation of Cu-Zn minerals at first, then Cu-Zn separation, then recovering sulphide by flotation, then recovering iron minerals by magnetic separation, then bulk flotation of Sn-W minerals after desliming" is developed. Furthermore, specific Sn-W collectors of BK411 and BK412 are applied into the processes and better indexes are obtained. The industrial indexes are listed as followings: the content of Cu, Zn, Sn, WO3 of ROM ore is 0.31%, 0.65%, 0.13%, 0.03%; Cu and Zn recovery are 82.23% and 37.79% respectively; 63.76% of Sn and 34.34% of WO3 go into the Sn-W bulk concentrates. Economic benefits are remarkable."

Jan 1, 2014

By J. Yianatos

The cleaning circuit operation and its effect on the plant metallurgical performance, was characterized at Los Pelambres concentrator, Chile. Experimental data from columns, scavenger and regrinding stages was evaluated. Each stage was characterized by size fractions, and the interaction between stages (columns, scavenger, regrinding) as well as the effect that circulating loads had. The approach for describing the flotation equipment operation (cells and columns) considered the collection and froth zones separately. This methodology allows for the identification of the impact that particle size distribution has on the actual collection and froth transport processes, independently. In this way the effect of regrinding on flotation recovery and grade can be related to the corresponding operating variables, e.g. pulp flowrate, air flowrate, pulp level and pulp density, among others. The effect of gangue entrainment was considered using an empirical dimensionless correlation. The interaction between the circulating load and the overall performance of cleaning circuit was evaluated. The circulating load was defined as the ratio between the solid flowrate of scavenger concentrate over rougher concentrate. It was found that the overall cleaning flotation circuit (column-scavenger) can operate at a relatively high and constant recovery for a wide range of mineral treatment. This is possible when the scavenger has the capacity for compensating the decrease in column recovery at larger circulating loads. Under the condition of high overall cleaning recovery, the rougher stage closely represents the plant recovery. However, at large mineral treatment conditions, the design characteristics (e.g. concentrate transport channel capacity and transfer boxes) as well as instrumentation, control facilities and operation, became bottle-necked. A simulator was developed using empirical models for each stage (column, scavenger and regrinding) in order to evaluate proper operational strategies for cleaning flotation circuits Keywords: flotation, cleaning, regrinding, Vertimill, simulation.

Sep 1, 2012

By Yuhe Tang, Jun Zhang, Jianguo Liu

"The nature high carbon graphite with fine particle size has low commercial value because of its narrow application range. In order to improve its value, this paper has studied the methods for nature spherical graphite. The nature spherical graphite can be used as the battery material in the field of electronic product battery and new energy automobile battery, basis on the physicochemical characteristics and particle feature of graphite. In this research, the Fixed Carbon (FC) grade of the graphite sample is more than 95.0% and the particle size of the graphite sample is from +325 mesh to -100 mesh. There are many methods for nature spherical graphite, including the fluidized bed airflow mill, the hydro-spheroidization mill and micropowder mill. The testing results indicate that the method of ACM micropowder mill is the best because the spherical shaping ratio and production yield of spherical graphite are both the best.According to the testing results of the ACM micropowder mill, the best process includes two stages of coarse crushing, four stages of fine crushing and twelve stages of shaping. And two kinds of spherical graphite products can be got, which are the product of D50=22.85 µm and the product of D50=15.43µm, and the whole yield of them is up to 54.43%. So, it lays a foundation for the high value utilization of this kind of graphite resources.INTRODUCTION Graphite is isomer of the diamond. Graphite ore resources are mainly concentrated in China, Brazil, India, followed by Czech, Korea, Mexico, Canada and other countries. Graphite ore has lots of characteristics by itself crystal structure, such as good resistance to high temperature, electrical conductivity, thermal conductivity, thermal shock resistance, good lubricity, plasticity, chemical stability and so on. So, Graphite is widely used in metallurgy, machinery, electrical, chemical, petroleum, nuclear industry, defense industry and other areas. [1,2,3] Natural graphite ore has low geological Fixed Carbon (FC) grade. FC grade should be enriched to more than 94.0% by mineral processing. [1,2] The particle size composition of this high carbon graphite affects its application value. The part of +100 mesh particle size has high application value. The part of -100 mesh particle size has low value because of its limited application field. In order to improve the value of-100 mesh particle size, this part high carbon graphite can be made into spherical graphite. And the value of the spherical graphite is great, it is more than 8 times of the feed. This paper has lots of tests for spherical graphite preparing with the fine particle size natural high carbon graphite. And it lays a foundation for the high value of this kind of resource."

Jan 1, 2018

By Liang Dianyin

In this paper, the molybdenite flotation tailing of cleaner-scavenger bank which has a mass of very fine particles has been taken as raw ore to be processed by flotation with/without ultrasonic. The effect of ultrasonic frequency, intensity, processing time and uploading location on molybdenite flotation efficiency is investigated by four-factor three-level orthogonal experiment, and the effect significances of these ultrasonic variables to molybdenite flotation efficiency have also been evaluated. Single-factor analysis of variance is conducted to investigate whether the effect of ultrasonic on molybdenum ore flotation efficiency is significant or not. The samples extracted from different ore species in different time have been mixed to analyze the particle size. The results show that the particle size of +38µm in concentrate obviously increases while the particle size of -25µmobviouslydecreaseswith ultrasonic, which means that ultrasonic is good for flotation due to sludge removing effect. Keywords: ultrasonic, flotation efficiency, sulfide ore, tailing, grade, sludge removing

Sep 1, 2012

By Bulelwa Ndlovu, Saeed Farrokhpay, Dee Bradshaw

The effects of phyllosilicate minerals on the flotation performance and froth stability of a copper ore was investigated. It was found that various phyllosilicate minerals affect the copper recovery differently however they all caused the flotation grade to be reduced. The effect of different phyllosilicate minerals on the froth stability followed the order of talc >> montmorillonite > muscovite > kaolinite > illite. The results demonstrated that there could be a relationship between the deleterious effect of phyllosilicate minerals on the flotation and froth stability. Talc and montmorillonite have both shown the highest effect on the flotation recovery and grade as well as froth stability. On the other hand, illite has the least effect on the both flotation performance and froth stability. Kaolinite and muscovite also affected the copper flotation grade (but not the recovery) while they also affected the froth stability. Therefore it is possible to control the flotation performance when phyllosilicate minerals are present via monitoring and controlling froth stability which needs to be investigated further.

Jan 1, 2014

By H. Matsuoka, M. Kawata, K. Haga, K. Mitsuhashi, C. Tokoro, A. Shibayama, R. Kawarabuki

"The mineral surface characteristic is important for the flotation because it affects the flotation behavior of the mineral. Conventionally, in the flotation process for Cu sulphide ores, the degree of ore floatabilities varies depending on the mineral phase such as chalcopyrite, bornite, or chalcocite. Therefore, mineral surfaces are treated with activators and depressants to control the floatability of target minerals and obtain high recovery performance. There are lots of flotation reagents which have many effects on ores depending on ore characteristics and conditioning methods. For example, sodium hydrosulphide (NaHS) as activator is known to have the effect of resulfurizing and activating oxidized surface of chalcocite and bornite. On the other hand, NaHS is reported to depress chalcopyrite floatability. In this study, the evaluation of mineral surfaces was conducted to predict flotation behavior. Activation of Cu minerals (chalcocite, bornite, and chalcopyrite) by NaHS was experimented. The three Cu minerals were treated in two steps. Firstly, they were oxidized in the drying oven. Secondly, they were treated with NaHS solution. After each treatment step, each mineral was measured by contact angle apparatus then analyzed by X-ray photoelectron spectroscopy (XPS). The results of surface characteristics after oxidation and NaHS treatment were utilized to accomplish the study’s objective. INTRODUCTIONCopper sulfide minerals such as chalcocite (Cu2S), bornite (Cu5FeS4), chalcopyrite (CuFeS2) are well-known abundant copper-containing minerals. Generally, these minerals are recovered and concentrated via collector flotation. In flotation, the wettability of the mineral surface is an important factor in its recovery. When the surface is hydrophobic, the mineral has high floatability and when the surface is hydrophilic, it has low floatability. Usually, Cu sulfide minerals have high floatability. However when their surfaces are oxidized, their floatability becomes lower in flotation. In this case of surface oxidation occurrence, activators are added before flotation to modify the surface property of the Cu sulfide minerals so that they can be floated at a certain flotation condition. Sodium hydrosulfide, NaHS, is known as one of the activators. Zhao et al. (2018) reported that NaHS is often used as sulfurizer for oxidized sulfide minerals (Becker et al., 2014, Clark et al., 2000, Newell et al., 2006, 2007, Newell and Bradshaw, 2007). Although the floatability of Cu sulfide minerals was raised by adding NaHS generally, the results of this flotation study showed that the flotation behaviors of mixed chalcocite, bornite, and chalcopyrite were different. Therefore, it was considered that NaHS works differently for each mineral."

Jan 1, 2018

By L. Q. Luo

SHP-F3200 wet high-intensity magnetic separator (HIMS) was successfully used to separate the complex and weakly magnetic iron ores being composed of specularite, limonite and siderite in Ji-uquan Iron and Steel (Group) Co Ltd (JISCO). It is more and more difficult to separate iron ores from gangues, such as quartz, jasperite and phyllite, as the properties of iron ores gradually become more complicated and refractory. Some technologies have been used to improve SHP-F3200 HIMS, including modifying angle of magnetic polar from 90°to 83°, cooling exciting coils by oil instead of air, adding reverse-washing device to wash off magnetic particles, adjusting the tooth-space of matrix from 5.0 mm to 3.5 mm or 2.5 mm, so as to enhance the recovery of fine iron ore particles. It is still difficult to meet the requirement for recovering more difficultly-separated iron and the demands for high-grade concentrate of iron. In this paper, after analyzing magnetic force exerting on iron ore particles within different separating sections of SHP HIMS, it is proposed to apply the flowing-film technique into the HIMS. Thus a new-type LY matrix is designed to form magnetic gradient vertically, combined with a special flowing-film feeder to improve the existing SHP HIMS. The moving pattern of magnetic particles in pulp in HIMS separation district also has been analyzed in this paper. And the test on the SHP-F700 HIMS shows, under the condition of iron ore containing 30.52% Fe, with particle size of ?0.074 mm accounting for around 75%, if applied with flow-film technique, the iron recovery will be up from 69.45% to 76.07%, by 6.62 percent, with the same grade of concentrates of iron. The calculation of iron yield of every size fraction and the tests showed that film magnetic separation (Film-MS) could promote the iron yield of each size fraction, denoting an excellent result of application of the film technique to SHP HIMS. The mechanism of the film magnetic separation technique is to convert the turbulent flow and disordered movement of dynamic mass particles in the pulp into a directional and ordered laminar flow along the surface of tooth plate so as to strengthen the separation effects.

Jan 1, 2014

By A. Güney

Currently, recycling technologies use relatively homogeneous plastics because hand-sorting waste feed is too expensive. Many promising technologies for separating mixed thermoplastics are being investigated, but they are still uneconomical and unreliable. Burning plastics for recycling is not used because of poisonous gases released when their burning. PET and PVC cannot be separated using conventional gravity separation techniques because their specific gravities overlap; PET density changes from 1.33 g/cc to 1.37 g/cc and PVC density is between 1.32 g/cc and 1.37 g/cc. For this reason, plastic recycling needs new techniques. Among these techniques froth flotation, also used in mineral processing, can be useful for its cost and simplicity. In this method, a plastic is selected from mixture, tried to regain its natural property, hydrophobicity. In this study the experiments were applied by using plasticizer reagents to make the selected plastics hydrophobic and us-ing NaOH to render the other hydrophilic. Post-consumed PET and PVC are evaluated by concerning the effects of selected parameters (particle size, concentration of plasticizer reagent, amount of NaOH, conditioning time and the effect of conditioning temperature). At the end of the experiments, optimum parameters for selective flotation of PET from PVC was found as particle size of -4.76 + 3.36 mm, NaOH amount of 30 kg/t, conditioning temperature of 75°C, conditioning time of 30 minutes, reagent amount of 300 mg/L. Consequently, PET was re-covered with 99.7% purity and 57% efficiency.

Jan 1, 2014

By Ghislain Bournival, Cagri Emer, Seher Ata

"It is well known among flotation practitioners that the contact angle can be correlated with the amount of material recovered from feed by flotation. The contact angle of solids can easily be modified by the addition of a collector. However, some collectors also have frothing properties thus altering the solid and bubble surface properties simultaneously. To avoid this problem, a technique has previously been used in which silanol groups are attached to the surfaces of the particles, but this method has its own problems. In this work, silica particles with various surface hydrophobicities were prepared using an esterification process. By using alcohols with different hydrocarbon chain lengths, from 4 to 12 carbon atoms, surfaces with a wide range of contact angles could be prepared. The technique was used in the modification of silica particles that were tested in a fluidized bed flotation column, and a laboratory mechanical flotation cell. In parallel experiments, dodecylamine (DDA) was used as a collector. It was found that irrespective of the type of flotation machine and surface preparation method, there was a close correspondence between flotation recovery and the contact angle of the particles. The silanation process has known drawbacks relating to the presence of moisture during the reaction, and the stability of the silane coating after it is been prepared. Esterification does not suffer from these disadvantages. This work has shown that the esterification technique is a robust alternative method for preparing hydrophobic quartz surfaces."

Jan 1, 2014

By M. M. Fan

In Florida?s phosphate industrial practice, the most favorable upper size limit of froth flotation is 1.18 mm which corresponds to particle weight of about 2.8 mg. Conventional froth flotation is not efficient in upgrading coarse particles (+0.425-1.18 mm). A limited number of studies have been devoted to understanding and improving coarse particle flotation. We have shown that the coarse particle flotation performance can be significantly improved by the presence of picobubbles generated by hydrodynamic cavitation. In this study, the size of picobubbles produced under certain hydrodynamic conditions was measured by a laser particle size analyzer. A size-by-size flotation performance analysis of coarse phosphate froth flotation in the presence of picobubbles is conducted in terms of flotation kinetics, selectivity and recovery. It was found that picobubbles doubled the flota-tion rate, increased the P2O5 recovery more significantly for +0.85-1.18 mm particles than +0.425- 0.6 mm and +0.60-0.85 mm particles. At a given acid insolubles (A.I.) rejection, the presence of picobubbles increased the P2O5 recovery by up to about 25%.

Jan 1, 2014

By Tsuyoshi Hirajima, Hideyuki Okamoto, Himawan .. T. B. M. Petrus, Keiko Sasaki

"Flotation of arseno bearing minerals from their copper ore has been an interest due to the increasing awareness on protecting the environment by minimizing the possibility of exposed arsenic compound. Some approaches have been proposed, but the mechanisms of separations have not yet fully understood. In this study, oxidation using oxygen was applied. Instead of the complex copper ore flotation results, pure single mineral of tennantite and chalcopyrite foatability was conducted using Hallimond tube. Resembled with the flotation results of copper concentrate containing tennantite, the separation possessed the best result at alkaline condition (pH 11) at where the arsenic content was reduced from 3300 ppm to 1800 ppm. In order to be able to understand the mechanism of the separation atomic force microscope (AFM) was utilized. AFM images showed changes in morphology and behavior when minerals were treated in both acid and alkaline condition. It was found that the morphological change showed the reaction products representing the rate of reactivity of tennantite and chalcopyrite. From the measured force of adhesion, it can be observed that in alkaline condition the surface of both minerals is more hydrophilic than that in acidic condition possessing higher value. This is in accordance with the X-ray photoelectron spectroscopy (XPS) spectra in which hydroxide moieties occupied the mineral surface in alkaline condition while elemental sulfur is in acidic condition."

Jan 1, 2014

By Edgar Schach, Tom Leistner, Markus Buchmann, Urs A. Peuker, Martin Rudolph, Marius Kern

"In this study, the flotation characteristics of a cassiterite-bearing fine-grained and complex skarn ore from a deposit in the Ore Mountains is investigated. The tests are performed using an oil-assisted column flotation approach to process very fine ore fractions and avoid losses of cassiterite into the tailings. First, process parameters are obtained for a finely ground artificial mixture of quartz, magnetite and cassiterite, simulating the real ore. Thereby, magnetite is used, as iron oxides can have a detrimental effect on the flotation due to a similar flotation behavior. In addition, they can act as a source of multivalent ions, which are known to reduce the concentration of collector molecules, active for flotation. Based on the results, selected parameters are further tested for cassiterite skarn ore from the Hämmerlein deposit including a pre-conditioning and a water exchange step to remove ionic contaminants. The process response is analyzed in detail by XRF (X-ray fluorescence) and MLA (mineral liberation analysis) to get a better understanding of the behavior of the single ore components. Sulfosuccinamate type surfactant is utilized as the collector, emulsifier and to reduce the froth destabilization through nonpolar oil. Sodium hexafluorosilicate is added as the depressant.INTRODUCTION Complex skarn ore deposits containing considerable amounts of tin, indium and other metals are located in the Ore Mountains region (Germany). In this study, a skarn ore from the Hämmerlein deposit was investigated. Due to the finely disseminated nature of this ore, past beneficiation attempts failed, and the ore was considered economically unprocessable. However, increasing resource demands brings it back into focus (Schuppan and Hiller, 2012). Cassiterite is the main tin bearing mineral in this ore. Due to its high density (~7 g/cm³), the predominant beneficiation technique is gravity separation (Angadi et al., 2015). Tin ores from disseminated deposits have to be extensively comminuted to reach a sufficient degree of liberation of the cassiterite grains. As cassiterite has a brittle nature, it is preferable enriched in small size fractions, during comminution (Angadi et al., 2015). Gravity separation methods become more and more inefficient for particles smaller 40 µm (Falcon, 1982), causing tin losses of up to 30 to 40wt.-% (Angadi et al., 2015). Thus, froth flotation of cassiterite was first utilized in Altenberg in the Ore Mountains as an additional processing step to reduce the cassiterite losses into gravity separation tailings (Bulatovic, 2010; Gruner and Bilsing, 1992). Although the reported lower size limits for an effective cassiterite floatability are often smaller compared to other minerals, the flotation performance is in general decreasing for small particle sizes < 10 µm (Trahar and Warren, 1976). Therefore, different approaches have been already investigated for the flotation of such fine cassiterite fractions to overcome the limits in particle size. Bilgen et al. investigated the shear flocculation of cassiterite with a sulfosuccinamate collector (Bilgen et al., 1994). The agglomeration flotation of cassiterite has been tested by Schubert et al. (Schubert et al., 1966), in which the selective coagulation of fine hydrophobic particles and oil droplets leads to an increase of the effective particle size. Recently, Leistner at al. investigated an oil-assisted agglomeration flotation for ultra-fine cassiterite ore fractions (Leistner et al., 2016). However, a poor response due to an increased concentration of Fe and Ca ions, unselective oil/gangue coagulation and froth instability, that is caused by oil/frother interactions, has been observed."

Jan 1, 2018

By Silvia França, Hudson Couto

"In this paper, an alternative beneficiation process was developed to recover nickel minerals from low-grade weathered ores. The studied sample, 0.3% Ni grade, is essentially composed of nickel sulfides (pyrrhotite and pentlandite); magnetite and silicates (mostly talc and amphibolites) are the primary gangue minerals. The particle size distribution was controlled using a grinding operation to avoid producing an excess of fine particles by overgrinding. The sample underwent a grinding step for the fine degree of liberation. The slimes (-20 ?m) were removed via two desliming stages in hydrocyclones (diameters of 1.5" and 2"); the ground material, which was classified in a range of (-150+20) ?m, was processed by column flotation in three different stages: rougher flotation for magnesium silicates, rougher flotation for sulfides, and cleaner flotation for sulfides, using pilot flotation columns (2" and 6" in diameter and 20 ft high). The goal of using the preliminary magnesium silicate flotation step was to remove hydrophobic minerals (mostly talc) that would float naturally with the sulfides, which would decrease the Ni grade in the concentrate, as well as to reduce the MgO content because this compound is considered harmful in metallurgical processes when a grade greater than 9% is used. The final concentrate obtained in the cleaner flotation step reached up to 2% Ni and 7.0% MgO. The global and flotation recoveries in the process were approximately 30% and 60%, respectively, due to the losses of Ni during the desliming process. Despite this low global recovery, the adopted beneficiation process can be considered an interesting alternative to produce nickel concentrate from tailings or waste materials."

Jan 1, 2014

By C. A. C. Sequeira, G. N. Anastassakis

Electrochemical processes occur on nano-, micro- and macro- scale in numerous applications such as fuel cells, batteries, hydrogen production, mineral extraction, water treatment, electrotherapy, sensors and many others. In most of these applications, gases evolve either at one or both electrodes due to electrolysis. These gases form bubbles play a crucial role in electrochemical systems. For example, in electrowinning (EW) that is used to extract and refine metals such as Cu, Zn, Ni, Mn, and Cd from their solutions, in most cases the solution is acidic and oxidation of water molecules at the anode is the common counter reaction, which results in the liberation of oxygen bubbles. This generally requires a high overpotential and accounts for a considerable percentage of the energy consumed in metal EW electrolytic cells, apart from producing acid mist that is very corrosive for other cell equipment and building structures. The behaviour of bubbles in electrochemical systems is still a complex challenging topic which requires a better understanding of gas bubbles hydrodynamics and their interactions with electrode surface and bulk liquid, as well as between the bubbles themselves. The objective of the current paper is to briefly review the fundamental hydrodynamics of both gas bubbles on the electrode surface and gas bubbles interaction with the liquid bulk solution. The current work also investigates the impact of gas bubbling and some operating parameters in copper EW, such as current density (100-500 A/m2), temperature (25-75ºC), acidity (50-300 g/L) and a typical chemical mist suppressant (<50 ppm). The results clearly show that both suppressant and temperature reduced the overall surface tension of the solution. Also, chloride concentration and applied current improved electrolyte flow and copper quality at higher current densities. The current paper contributes to the development of mineral processing (specifically to copper hydrometallurgy), as it deals with fundamental hydrodynamics and interactions of gas bubbles that formed during copper EW and play a crucial role in copper electrochemical systems.

Jan 1, 2018

By F. Q. Cheng

As the important potash, the product yield of KCl in winter is low and the resources waste is serious according to the deficiency of collectors, which can be used in this condition currently. This paper studied on the change of contact angle, turbidity, and flotation recovery of KCl particles when different chain lengths, ratios of amines were used as collectors in KCl flotation process to get a new mixed collector. The contact angle values of KCl crystal in its brine solution added different amine collectors were first measured by captive bubble method. The turbidity of brine solutions were then measured by the laboratory turbidimeter at room temperature when different amine collectors were contained. In the end micro-flotation experiment using mixed amine with fixed ratios and ODA as collectors respectively at 5 °C, 23 °C were performed. The results show when the ratio of the mixed amine is DDA- 20%, ODA-60%, C20-20%, the contact angle at KCl surface is the maximum and the hydrophobic state is best. Meanwhile the result of turbidity measurement indicates that the dispersion of mixed amine colloids is better than the ODA collector due to the addition of DDA, which plays the role of frother. The flotation results also prove that the mixed amine is not only fit for the KCl flotation at room temperature but also fit for its flotation at low temperature. This study provides strong technical support to extend the production time of potash business in Chaerhan areas in China.

Sep 1, 2012

By P. Basarova

The attachment of bubbles onto a collecting surface is an ubiquitous natural phenomenon, playing a critical role in numerous practical processes. The goal of the project is to broaden the knowledge about hydrodynamic interactions between small bubbles and large solids that occur in nature and industrial processes. Focusing on collision processes between a single rising bubble (Db<1 mm) and a larger falling spherical particle in stagnant liquid, the theoretical model describing the bubble trajectory is given here. The model is based on analysis of forces acting on the bubble, and utilizes equation for the bubble motion. Mobile and immobile type of bubble surface mobility are considered. The calculated results are compared with the experimental data; here a high-speed video camera was used to capture the bubble motion and bubble-particle interaction. Very good agreement between experimental and calculated data was found. For both types of surface mobilities, the bubble deviation in the horizontal direction is nearly linear. The proportion constant is bigger for immobile bubble surface and increases with the bubble size. Furthermore, particular forces acting on bubble were studied. A similar course of relative bubble velocity and force impact was observed for identical bubble position. For cases when the bubble centre is close to the particle axis, only deflection in one direction is observed. When the bubble is reaching the maximum trajectory, the force ratio is changed. The bubble is firstly pushed away from the particle, but when it is within close distance from the particle, the bubble is pushed towards the particle.

Sep 1, 2012

By Dave Deglon

The Western Cape Mineral Processing Facility (WCMPF) is a collaborative educational initiative between the Departments of Chemical Engineering of the University of Cape Town, the University of Stellenbosch and the Cape Technikon. The WCMPF was established in 1989 with the aim of improving mineral processing education in the Western Cape. Since its inception the WCMPF has had a number of successes in this area, especially in improving the quality of mineral processing practical training. In addition, the WCMPF has played an important role in promoting liaison and interaction between tertiary educational institutions teaching mineral processing in the Western Cape. Over the past decade the WCMPF has played a key role in the education of over five hundred mineral processing graduates and diplomates. This paper presents an overview of the activities of the WCMPF and attempts to encapsulate the ‘lessons learned’ from over a decade of successful functioning as a collaborative educational initiative in mineral processing.

Jan 1, 2003

By U. Dmitrakova, G. Sedelnikova, D. Kim, E. Savari

"The paper presents the results of research on the development of gold and silver extraction technology from refractory gold sulphide flotation concentrate of one deposits of Nord-East of Russia. The concentrate is due to the complex mineral composition. Gold and silver are finely disseminated in sulphide minerals (arsenopyrite and pyrite partially oxidized by 7-11%). These are characterized by high content of silver 219 g/t and sulphide sulfur 32%, the presence of poorly soluble silver minerals (silver sulfosalts, fahlore, finely dispersed hypergenic acanthite in iron hydroxides and jarosite, etc.), and impurity minerals capable of interacting with cyanide (pyrrhotite, marcasite, nonferrous sulphides) and causing higher than normal cyanide consumption. Pretreatment of refractory sulphide concentrate by biooxidation using a mixed association of mesophilic and moderately thermophilic bacteria at a temperature of 36-40 °C for 120 hours oxidized arsenopyrite by 97.5%, pyrite by 93.5%, unlocked refractory gold, and generally oxidized the minerals absorbing cyanide and oxygen before cyanidation. Further oxidation of these minerals-absorbents was facilitated by the aeration in calcareous medium of the solid biooxidation residues of the concentrate. Sorption cyanidation of the solid biooxidation residues with addition of lead (II) of recovered 91.2% of gold and 82.9% silver from biooxidation residue, compared with 80.1% and 46.6%, respectively, for sorption cyanidation without the preceding biooxidation step. Biooxidation of the concentrate prior to cyanidation improves the recovery of precious metals, especially silver, and significantly reduces cyanide consumption from 18.7 kg/t to 3-5 kg/t of concentrate. INTRODUCTION Biooxidation of gold sulphide concentrates using acidophilic microorganisms has been successfully applied worldwide (van Aswegen et al., 2007; Gericke et al., 2009; Sovmen et al., 2007; Sovmen et al., 2009). At least 15 full-scale plants for tank biooxidation of sulphide concentrates are presently in operation, and the construction of new ones is planned (Bulaev et al, 2015)."

Jan 1, 2018

By T. Suzuki

Acid leach liquors from spent lithium-ion batteries employing lithium cobalt dioxide (LiCoO2) as a cathode active material contain valuable metals such as cobalt and lithium, as well as common metals such as aluminum and copper. The objective of this study was to develop a hydrometallurgical process providing a high selectively between aluminum, cobalt, copper, and lithium from hydrochloric acid solutions. Batch experiment results showed that selective hydroxide precipitation approach was not suitable because a significant amount of cobalt and lithium was co-precipitated with aluminum and copper hydroxides. In contrast, batch experiments and the subsequent data analysis indicated that the sequence of solvent extraction circuits using PC-88A, Acorga M5640, and tri-n-octylamine (TOA) extractants effectively separates four metals of interest. In the first circuit of the proposed process, copper was selectively extracted by Acorga M5640 at the pH 1.0-2.0. Aluminum, cobalt, and lithium remain in the aqueous phase. In the second circuit, aluminium is selectively extracted by PC-88A at pH 2.0-2.5. For the separation of remaining cobalt and lithium, Acorga M5640 provided higher separation efficiency compared to PC-88A single extractant and PC-88A/TOA mixed extractant. However, the stripping efficiency of cobalt from the Acorga M5640 organic phase was found to be low (less than 10 %). Therefore, PC-88A/TOA mixed extractant rather than Acorga M5640 is an advisable choice for the separation of cobalt and lithium. Keywords: spent lithium-ion secondary batteries, solvent extraction, lithium, cobalt

Sep 1, 2012

By Francesco Vegliò, Luigi Toro, Francesca Pagnanelli

"Different hydrometallurgical processes have been studied in order to recover manganese(II) from oxidised minerals such as MnO2 (Vegliò and Toro, 1994). An innovative acid reductive leaching carried out in soft experimental conditions was here considered using agro-industrial wastes containing carbohydrates as reducing agents (Vegliò et al., 1998).The leaching process was investigated from a kinetic and equilibrium point of view in order to optimize the experimental conditions and obtain high purity and concentrated MnSO4 solutions.The overall leaching process (not considering the complex network of intermediate oxidation reactions of the carbohydrates in hot sulphuric acid medium (Vegliò and Toro, 1994)) can be described by the following reaction:24 MnO2 + C12H22O11 + 48 H 24 Mn2+ + 12 CO2 + 35 H2O (1)A Shrinking Core Model (SCM) was modified by a variable activation energy term to take into account both the variable reagent concentrations and the reaction rate change with respect to the manganese dioxide conversion. The influence of the particle size in the kinetic model is discussed with the support of SEM analysis and BET surface measurements before and after leaching.Manganese extraction yield was maximised (170-190 g/L) using appropriate carbohydrates and acid excesses, while impurity concentrations were kept low (Fe<10ppm and Ca<300ppm) pre-treating the ores, using hydroalcoholic leaching medium and different combinations of down-stream processes. In particular precipitation, solvent extraction and adsorption onto active carbon were tested to eliminate Fe and Ca from MnSO4 solutions."

Jan 1, 2003