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By A. Mainza, I. Govender, J. Waters

"The study of the properties of mineral processing suspensions is important in understanding how a circuit might behave. As soon as the predominantly dry ore enters a wet milling stage the ore properties undergo changes as a ‘slurry’ is created. Slurries can be classified in terms of their physical properties (particle density, solids concentration, particle size and size distribution, particle shape), and their flow properties such as rheology. Slurry flow regimes are classified into true homogeneous, pseudo homogeneous, heterogeneous and fully segregated, and only true homogeneous and pseudo homogeneous suspensions can be characterized by their flow structure. A class of the heterogeneous regime are the so-called dense phase or settling slurries - those which result in a clear water surface on standing, although they may approach a pseudo homogeneous state if suspended for a sufficient period of time. They are usually extremely difficult to characterize by their rheological properties alone and the rheological characterization of these slurries has always posed a problem, especially at higher concentrations. Previous rheological studies have focused on the individual concentrator units dealing with milling, classification, pumping, flotation, fine grinding, thickening.In this work an attempt was made to characterize two ore types (copper and a Platreef platinum ore) using a custom built Paterson and Cooke tube rheometer, at concentrations up to 43% by volume. After applying a turbulence correction, results showed Bingham plastic behavior. A conventional vane rheometer was then used to compare the rheological behavior of platinum concentrator streams. A size criteria was used to identify any rheologically dominant streams."

Jan 1, 2014

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

"The separation of fine or even smaller size mineral particles with conventional methods is inefficient due to the specific properties of fines (small mass, high specific surface area, and high surface energy per unit area). Hence, the production of high-grade concentrate with high recovery is very difficult to impossible and a significant share of mineral values is lost to the tailings. The aim of the current research is to investigate the possibility to efficiently separate value minerals from gangue of fine particle size. The objective of the current work is to develop separation schemes of fine mineral particles by combining an initial stage of particles agglomeration with the use of collectors (hydrophobic agglomeration) with a subsequent conventional separation method. In the current research, magnesite was used as mineral value to be separated: a) from quartz, and b) from mineral mixture (serpentine, ilmenite, and olivine). In each case, tests on single minerals and artificial mixtures were carried out. After hydrophobic agglomeration, the separation of magnesite from quartz was achieved by settling; in the second case (gangue: serpentine, ilmenite, and olivine), magnetic separation of the co-agglomerated gangue was applied. In both cases, the results of the preliminary tests on single minerals suggest that the separation of mineral value is feasible and efficient. These findings were also confirmed from the results of the tests on artificial mixtures of magnesite and gangue, either quartz only or mineral mixture. Both separation schemes provided with magnesite concentrates of commercial grade (95% magnesite) with high recovery. INTRODUCTION The generation of fine particles is inevitable in many operations of mineral commodities processing. Especially in the case of low-grade ores, the mineral value is finely disseminated in the ore, and considerable liberation occurs at a fine size range. Although there is not a uniform classification system with respect to mineral particles size, fines are usually characterized the particles with a size range of -100µm+20µm, very fines those of -20µm+5µm, ultra fines of -5µm+1µm, and colloids smaller than 1µm (Sivamohan, 1990)."

Jan 1, 2018

By O. D. Khmelnitskaya

The research on selecting of an efficient technology of pyrite cinders complex treatment, sulfuric acid production wastes, have been made. The grades in the initial product were 2.04 g Au/t, 35.0 g Ag /t, 0.38%Cu, 1.1% Zn. Laboratory tests on cyanide technology, thiourea and sulphite leaching were carried out. Magnetic and flotation beneficiation and biohydrometallurgical technology were tested. After considering the results of the tests, the most economically efficient technology of pyrite cinders complex treatment with cyanide leaching of precious metals was determined. The technology involves water washing of soluble copper and zinc compounds, lime treatment and cyanide leaching of gold and silver, detoxification and utilization of mineral wastes. The precious metals are recovered from solutions by cementation onto zinc. Copper is recovered from rinse waters by SW/EW and then zinc is precipitated as hydroxide. All the solutions and organic agent are used in recirculation and therefore the technology is practically waste-free. Mineral wastes can be used as iron-containing materials for cement industry. The technology has been tested in pilot-plant scale under continuous operation with complete re-circulation of cyanide solutions. In this process recovery of 54% Au, 45% Ag, 30% Cu and 50% Zn has been achieved.

Jan 1, 2014

By J. M. Ortiz, J. Haas, W. Kracht, G. Pamparana

This work explores the effect of ore hardness variability on the design of a solar photovoltaic system with battery storage and grid backup, to operate a semi-autogenous grinding mill (SAG). First, a case of two synthetic ore populations was studied, without any consideration of spatial distribution. The mean and variance of the ore hardness (measured in specific energy consumption, SEC) of both populations were subjected to a sensitivity analysis. The operation was evaluated with one and two stockpiles. The latter allows classifying according to ore hardness as a way to adapt the SAG energy consumption to the solar cycle. The results show that using two stockpiles allows achieving a larger autonomy (i.e. less energy imports) at lower total costs, especially when the difference of mean hardness between the two populations is large. The difference in variance (between the two populations) has a smaller impact on the design recommendations. Second, a case study was performed considering the spatial distribution of geometallurgical units. Two cases were considered: (a) brownfield, when there is historical information of the actual variability of the ore hardness; and (b) greenfield, when the system design relies mainly on geometallurgical modeling. Brownfield and greenfield planning result in similar sizing recommendations of the solar power plant, if precise drill cores are available. In this case, geometallurgical modeling is an effective tool for forecasting the energy demand necessary for designing the power plant.

Jan 1, 2018

By Sanja Miskovic, Manjunath Basavarajappa

In this study, a coupled CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) approach is used to simulate two-phase, solid-liquid flow within the flotation cell. Turbulence plays a key role in flotation cells and level of turbulence is affected locally by the presence of particles. Turbulence in the flow is modelled using Reynolds Averaged Navier-Stokes (RANS) based k-e model. Using particle transport and spatial distribution, mixing mechanism for differed sized particles are analysed. By including the effects of particle-particle collision, particle rotation, and particle translation, as well as the volume occupied by the particles in the fluid, CFD-DEM approach can be used to accurately predict the motion of particles in the turbulent solid-liquid flows with strong coupling. Electrical resistance tomography (ERT) is used to investigate the effect of impeller size, shape, off-bottom clearance and impeller speed on mixing and suspension behaviour inside flotation cell. The effect of flotation impeller design, impeller size, and off-bottom clearance on flow hydrodynamics is investigated. In the case of moderate and high solids loading (> 10 %w/w), energy is dissipated through inter-particle interactions and four-way coupling becomes important (Derksen 2003). The main goal of this study is to understand the effect of particle size and concentration on flow dynamics at high Re in highly turbulent systems using advanced modelling and measurement techniques. Experimental measurements obtained by ERT) system allowed detailed mapping of temporal hold-up profiles of the dispersed phase. Impeller size and off-bottom clearance are found have significant effect on the particle suspension characteristics.

Jan 1, 2014

By Kauko T. Ingerttilä, Jouko O. Kallioinen, Jaakko O. Leppinen, Alexander V. Lashkul, Vladimir E. Nenno

The Separation in Froth (SIF) technique is based on the idea that the pulp is fed directly onto the froth layer prepared on the surface of liquid medium providing an effective method for separation of coarse particles up to a few millimeters size. Thus the SIF process can result in substantial savings in grinding energy and flotation chemicals. In this work flotation of apatite, calcite and silicate minerals from various industrial sources was investigated using laboratory and pilot plant-scale SIF machines. Flotation of diamonds was also investigated on laboratory scale. It was observed that all the minerals mentioned above can be successfully floated up to about 3 mm particle size. Beneficiation tests with the coarse fractions of classification circuits indicated that final grade calcite concentrate can be obtained with over 90% recovery in one SIF step in this grain size (typically 0,1 to 1,5 mm). Similarly, substantial upgrading of coarse apatite was achieved without grinding it to the fineness required by conventional flotation. SIF could also be applied to the recovery of coarse apatite from the tailings of a conventional flotation process. The capacity measured in the pilot plant test runs for a 1 m2 cell was typically 30 t/m2h. Presently, a full-scale process using the SIF technology is being installed for coarse apatite recovery.

Jan 1, 2003

By Georg Unland, Thomas Wegner

"Different types of impact crushers use the physical effect of impact to crush rocks. The rocks can vary from soft to hard and from ductile to brittle but they should never be abrasive. Since the principles of impact crushing of larger rocks are hardly investigated these crushers are still sized rather by empirical than by scientific approaches.In order to investigate the principles of comminution by impact of large rocks a test rotor was developed and rocks of different dimensions were tested. The integrated measuring devices of the rotor enable the recording of impact forces and of absorbed impact energy with high resolution during the contact time.Since impact crushers stress the rock particles with a defined velocity the main crushing properties are gained as a function of the applied velocity and the particle size of the rock: likelihood of breakage, contact time, maximum crushing force, mass specific crushing work, surface related crushing ratio and crushed fragment shape distribution."

Jan 1, 2003

By G. P. Karmakar, K. K. Chandan

"The drilling mud is an essential part of the drilling process, which plays a major role in keeping safe and efficient oil and gas well drilling. In the oil industry, bentonite clay dissolved in water produces the simplest type of drilling muds. Bentonite clay contains montmorillonite particles. These particles are dispersed uniformly in water and such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds. The bentonite clay easily dissolves in water and increases the viscosity of the water, which is one of the most important properties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for building up of the viscosity of the clay-water system. The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil and gas well drilling process. The behavior of drilling mud greatly depends upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations. In this work, a comprehensive study has been carried out to find out the effect of added polyacrylamide (PAM) polymer, surfactant, pH and salt concentrations on the dispersion/ flocculation characteristics of bentonite clay-water system. It has been observed that the increase in PAM dosage reduces the residual turbidity and improves the settling rate of the bentonite particles. The flocculation rate has also been found to be better under higher pH conditions. The combined effect of salt concentration and PAM dosage improved the overall flocculation efficiency of the system.INTRODUCTIONIn the oil industry, bentonite clay dissolved in water produces simplest type of drilling muds. Bentonite clay containes montmorillonite particles. These particles are dispersed uniformly in water. Such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds (Akther et al., 2007). The bentonite clay easily hydrates in water and increases the viscosity of the mud system (Razi et al., 2013; Meng et al., 2012). Bentonite clay in the drilling mud increases the viscosity which is one of the most important prop erties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for the building up viscosity of the clay-water system (Sonmez et al., 2013). The drilling mud is an essential part of the drilling process, which plays a major role in keeping a safe and efficient oil or gas well drilling (ASME, S. S. C., 2005). The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil or gas well drilling process. This behavior of drilling muds greatly depend upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations (Yu and Amanullah, 2005; Akther et al., 2007). Bentonite particles form aggregate under certain conditions including high temperature, and high concentration (Luckham and Rossi, 1999). If the quality of bentonite is not sufficient to accomplish intended viscosity of the muds, it is essential to add certain additives to increase the viscosity and prevent aggregation of the system (Razi et al., 2013). The anionic polymer bearing sample can build up inter-particle bonds between the polymer and clay particles. The addition of various additives like, polymers control the dispersion and enhance the viscosity of the mud by controlling the flocculation of montmorillonite particles in bentonite dispersion (Heller and Keren, 2002; Mahto and Sharma, 2004)."

Jan 1, 2018

By Nilmara Dias, Maria Margarida Martins, Maria Teresa Carvalho

"The heavy residual fraction of the mechanical and biological treatment (MBT) plants treating undifferentiated municipal solid waste is mostly composed by inert materials, such as glass, stones, ceramics and brick. Glass, appearing in significant grade and amount, is not recycled today due to the high content in the other materials, mainly stones. All these materials have approximately the same density but stones have significantly different shape from other materials particles. In this paper it is presented the research developed to eliminate stones appearing in the fine fraction (2.8-8 mm) of the MBT plants heavy residual fraction (MBTr) using a shaking table operated in dry conditions. Two different samples from two different MBT plants were used. Firstly, the samples were characterized (materials content and particle size analysis). Then, laboratory work was carried out to optimize the operation of the shaking table, by changing the machine parameters, deck slope and movement frequency. The study showed that it is possible to upgrade the product in glass. The best results, obtained with one single stage of processing, were 82% content in glass with 84% in recovery, in the glass concentrate, when the coarser fraction (-8+5.6 mm) of one of the MBT plants was used. With the intermediate particle size fraction (-5.6 + 4mm), the glass concentrate attained 74% content in glass with 91% recovery."

Jan 1, 2014

By Neill Bartie, Jacques Eksteen, Sharif Jahanshahi, Shouyi Sun

The gradual increase in Cr2O3 levels of UG-2 ores has become a matter of concern for platinum producers in South Africa due to the formation of chromite spinels in melters. The effect of bulk FeOx/MgO ratio, Cr2O3, temperature and oxygen partial pressure on phase stability and composition in the system FeOx-MgOSiO2- Cr2O3-Al2O3-CaO has been studied between 1400°C and 1600°C using the drop-quench technique. An increase in temperature was found to result in a decrease in [Fe/Cr]spinel. An increase in bulk FeOx/MgO caused Mg, Al and Cr in spinel to decrease, forming more magnetite relative to other spinels. [Fe]spinel decreased and [Cr]glass increased with a decrease in oxygen partial pressure.

Jan 1, 2003

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 Emile Scheepers, Chris Aldrich, Jacques J. Eksteen

The pneumatic injection of CaC2 powder into molten iron has become a very reliable and effective way to carry out desulphurisation. The key variables that influence the kinetics of this process are the condition and composition of the top slag, the oxygen activity in the hot metal and the injection conditions. Notable injection parameters include carrier gas flowrate, reagent flowrate, lance depth and initial sulphur concentration. A one-dimensional, steady-state model for momentum, heat- and mass transfer in rising gasliquid- powder plumes was developed for conditions relevant to the CaC2 refining process at Saldanha Steel?, South Africa. Combined with a model that predicts the contribution of the topslag to the process, the overall rate of desulphurisation as a function of time was determined, thereby quantitatively demonstrating the influence of the above-mentioned injection parameters on the kinetics of the desulphurisation process.

Jan 1, 2003

By W. Pawlos

"The paper will present the methods of visual observation and recording of movement paths of coal grains of different physical properties in the paramagnetic liquid. The paths were recorded with a video camera in the working chamber by means of a specially constructed device, acting as a periscope, which were then transformed into digital images.Experimental movement paths were confronted to the paths obtained in a theoretical way by means of solving differential equations of movement. The outlet level of a grain of the same physical properties from the separator is a random variable with normal distribution which modal value is equal to the outlet level of a spherical grain, calculated from the solution of grain movement equations. At these assumptions it is possible to calculate the height of the passage from the separator working chamber to separate a given product with a given separation accuracy, measured by a probable error and to determine separation conditions."

Jan 1, 2003

By Ljudmil S. Grigorov, Eric Forssberg, Hanumantha Rao Kota, Robert J. Pugh, Lidia B. Alexandrova

"The effects of mixed collectors on some physicochemical parameters (thin film lifetime, kinetics of expansion of the three-phase contact, equilibrium three-phase contact angle and surface tension) involved in the elementary act of flotation were investigated experimentally.We have used the microscopic thin balance developed by Scheludko et al (1970) to study the stability and interactions within the thin film between the silica surface and air bubble with (i) a long chain C10 amine and (ii) a cationic/anionic surfactant systems consisting of mixtures of a long straight C10 chain amine with long straight chain C8, C10 and C12 sulfonates at 1:1 molar ratio. The experiments were performed at a range of concentrations at pH 6.5. The equilibrium contact angle was measured with a microscope technique using the modified Mingins-Sheludko method (Mingins and Scheludko, 1979). The surface tension was measured by the method of Wilhelmy (Adamson, 1960). It was found that the mixed surfactants caused lower contact angles, lower rates of the thin film rupture and longer film lifetime, compared to the pure amine system."

Jan 1, 2003

The introduction and subsequent ascendancy of autogenous and semi-autogenous milling for comminution circuits has undoubtedly lead to many economic advantages. From a process viewpoint, however, at least one downside has been the sensitivity of these machines to process input variations. Foremost among these is ore competence, though feed size comes a close second. This sensitivity is due to the reliance of ag/sag mills on the feed ore for their grinding media competence and size. Autogenous (ag) mills are the most sensitive in this respect with semi-autogenous (sag) mills being increasingly less so as the ball charge is increased. Increasingly designers and operators are recognising the importance of feed size and the benefits of manipulating it to improve performance. This has been achieved by installing additional crushing/screening capacity ahead of the ag/sag, better operation of the primary crusher, better control of segregation cased by stockpiles and bins and by changing blast design/practices to modify the ROM size distribution. This paper describes the influence of feed size distribution on ag/sag mill performance with reference to a range of plant data. It particularly concentrates on how changing blasting practice to modify ag/sag feed size can have a considerable overall benefit.

Jan 1, 2003

By Francisca San Martín, Martin Rudolph, Willy Kracht, Tomás Vargas

It has been shown that bacteria Acidithiobacillus ferrooxidans can be used to depress pyrite in seawater flotation at natural pH, which opens the possibility for its use as an alternative to lime to depress pyrite in copper sulfide flotation. In order to have a better understanding of the mechanisms involved in pyrite depression with A. ferrooxidans, an exploratory experimental campaign was carried out, including attachment density and contact angle measurements, and the effect of adding bacteria before or after collector. Biodepression of pyrite improves when increasing pH from 3 to 8, with a decrease in recovery from 92% to 36%. This increase in depressing capability is accompanied by an increase in attachment density, from 2.58×108 bacteria/g to 1.99×109 bacteria/g at pH 3 and 8, respectively, suggesting that the mechanism of depression is related to the attachment of bacteria to the pyrite surface. It was observed that the conditioning sequence with collector and bacteria influences the biodepression capacity of A. ferrooxidans. Having as a reference a value of pyrite recovery equal to 97%, when using only xanthate in seawater flotation at pH 8, the effect of both conditioning with bacteria-followed-by-xanthate and xanthate-followed-by-bacteria were assessed. When bacteria were added before the collector, the recovery of pyrite decreased to 36%. On the other hand, when bacteria were added after collector, the recovery was 64%, showing that biodepression of pyrite with Acidithiobacillus ferrooxidans is more efficient when the conditioning is carried out first with bacteria. The contact angle values show that there is little effect of the second component added to the system, i.e., if pyrite is first conditioned with bacteria, the contact angle does not change significantly once the xanthate is added (bacteria-followed-by-xanthate). The same was observed when the conditioning sequence was xanthate-followed-by-bacteria.

Jan 1, 2018

By Rolf Lauten, Yongjun Peng, Yufan Mu

"Biopolymers, produced from cellulosic biomass, have promising prospects of application as depressants in mineral processing. In this study, three different types of biopolymers (i.e., DP-1775, DP-1777 and DP-1778) were used to study the effect of polymer structure on flotation of un-activated pyrite, copper activated pyrite and chalcopyrite. It was found that the depressing effect of DP-1775 and DP-1778 was much stronger than that of DP-1777, and pyrite was depressed to a greater content than chalcopyrite with the same biopolymer at the same dosage. The biopolymer concentration played a vital role in determining the degree of depression. For each biopolymer, the higher the concentration, the greater the minerals were depressed. The mechanism underpinning the depressing effect of these biopolymers was explored in this paper. The concentration of biopolymers could determine the properties of the adsorption layer and the confirmation of biopolymer chains on mineral surfaces. The biopolymer molecules may aggregate when polymer concentration was over a critical value. Molecular weight and functional groups of biopolymers were the key factors characterizing the depressing capability of different biopolymers. Differences between the tested biopolymers and features of the adsorbed layer might account for the observed trends in ability to depress pyrite and chalcopyrite flotation. The greater depressing effect of biopolymers on pyrite over chalcopyrite might result from the preferential adsorption of biopolymers on pyrite over chalcopyrite."

Jan 1, 2014

"Wet low intensity magnetic separation has been used for the recovery of magnetite for decades. As high-grade reserves continue to decline, low grade magnetite ores are being targeted for iron production. Low grade magnetite mineralisation is typically fine grained and requires fine to ultrafine grinding (P80 40 - 30 µm) to liberate it from, predominantly, silica/silicate gangue matrices. Grinding to such particle sizes requires high power consumption and produces excessive fines which impact negatively on wet magnetic separation and tailings dewatering. In addition, the dearth of fresh water for mineral processing in arid areas impacts negatively on the economic viability of low grade magnetite projects. These challenges have motivated innovation in dry magnetic separation technologies for the beneficiation of magnetite that can be economically applied on a large-scale. Such technology has been developed in the Cyclomag Planar magnetic separator (PMS) invented by South Australia-based Christopher Kelsey of IMPTEC P/L. The significant gangue mineralisation associated with magnetite ores in South Australia is quartz. In this study, the performance of the Cyclomag PMS on the recovery of magnetite mineral from magnetite-quartz blends was investigated. Magnetite-quartz blend were subjected to the PMS at varying control parameters - magnet discs rotation speed, inlet airflow and feeder speed. The study showed a successful dry separation of magnetic mineral from non-magnetics using the Cyclomag PMS. The PMS has potential to effectively recover magnetite mineral."

Jan 1, 2018

By Bruno Michaux, Markus Reuter, Martin Rudolph

"It is relatively well-established in the literature that the flotation of calcium minerals using fatty acids as collector is very sensitive to the process water composition. In particular, hard waters have often been reported to strongly reduce the target mineral recoveries due to the formation of insoluble compounds such as calcium and / or magnesium dioleate, thus reducing the amount of collector available for adsorption onto the mineral surface. In this study, the flotation of a fluorite pre-concentrate was performed with tall oil, an industrial collector essentially containing fatty acids. The tests were performed in a variety of synthetic waters to simulate multiple degrees of water hardness, and to differentiate the role of magnesium and calcium ions on the flotation performance. The flotation tests revealed that, under the studied conditions, a significant difference between flotation in calcium-rich and magnesium-rich waters was observed, suggesting strong ion-specific effects in the system. Specifically, calcium-rich waters slightly improved the fluorite recovery, whereas magnesium-rich waters caused a decrease in recovery by as much as 20%. This paper is focused on the flotation kinetics aspect of the system. This approach highlighted the interesting finding that calcium ions did not simply increase the fluorite recovery, but also significantly increased its flotation kinetics. The magnesium ions, on the other hand, had the exact opposite effect.INTRODUCTIONAs the mining industry is facing an increasing number of issues related to its fresh water consumption, the idea of using alternative water sources for mineral beneficiation is gaining significant momentum. As a result, a proper understanding of the role of water chemistry in flotation is becoming more and more urgent, leading to an increasing number of studies on this topic."

Jan 1, 2018

By G. F. Zhang

Yunnan mineral is a kind of containing Ta-Nb rare earth deposit, the most potential economic valuable element in it is Sc, and raw mineral has 17.0 g/t Sc. Take the character of Sc into account, the key problem in producing scandium chloride molten salt by adaptive technology is how to man-ufacturer anhydrous scandium chloride molten salt. During the course above, the key problem is that preventing Scandium chloride from being hy-drolyzed into ScOCl. The ScOCl content of molten salt not only affect purifying scandium but al-so do harm to the production of Mg-Al alloy. In order to restrain the creation of ScOCl, add ammo-nium chloride into molten salt. As long as ScOCl is created, it would be chloridized. Thus, during the course of dehydrating anhydrous chloride molten salt this method prevents scandium from hydrolyzing. Accordingly, the key phase of this producing course is eliminate ammonium chloride and the surplus crystal water, and the most crucial of it is restrain scandium chloride from being hydrolyzed into ScOCl. This research analyzed the theory that ammonium chloride is trend to be hydrolyzed into ammo-nium chloride, and propose the research scheme of restraining this process from creating ScOCl. The new process of restraining the generating of ScOCl and dehydration for crystal water rare earth chloride is adopted: Inert gas temperature increases rapidly to a certain degree to eliminate ammonium chloride and crystal water. The experimental research were done such as : the temperature of eliminating ammonium chloride and crystal water, amount of ammonium chloride, time, temperature growth speed, influence of inert gas flow toward to scandium percent hydrolysis, whereby, we conclude the optimal process condition in this period: Temperature: 400°C, proportion of oxidized scandium and ammonium chloride is 1:1.5(Proportion of oxidized scandium and additional salt is 1:5.4), time is 120minute, temperature growth speed is 10?/min inert gas flow is 5L/min.

Jan 1, 2014