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By A. V. Nozhkina

"Transformation of diamond into graphite was investigated in the region of diamond metastability under the action of media chemically active relative to carbon in the temperature range from 770 K up to 2200 K and pressure range from 10-3 Pa up to 3 GPa/IV VIII group metals of periodic system and oxygen were used as media chemically active relative to diamond.Methods of electron diffraction, chemical analyses, emission spectroscopy and X-ray phase analyses were used for determination of the reaction products.It was found that in the region of diamond metastability the stage of catalytic phase transformation of diamond into graphite took place during the interaction between diamond and metal. Metal reduce activation energy for transition of diamond into graphite from 109,4 kcal/mole to 77,4 kcal/mole.Kinetic of phase transformation of diamond into graphite was investigated.Pressure does not considerably influence on the rate of phase transformation of diamond into graphite in the presence of transition metals."

Jan 1, 2003

By Daniela Venter, Stephen Chryssoulis, Ken Stowe

"A sampling campaign was conducted at Kemess in order to identify and assess the chemical and physical factors, which control free gold flotation kinetics in the rougher and cleaner circuits. The rationale behind this approach was that accurate knowledge of the parameters affecting free gold flotation kinetics, can be used to determine how to accelerate free gold flotation. Collected samples were composites of 5-6 cuts over a four-hour period, at steady plant conditions.In the rougher circuit, coarser equidimensional gold particles floated ahead of the finer grained and the flaky gold. Sulphur followed by molybdenum and to a lesser extent silver enhanced gold flotation kinetics, while hydroxyl followed by carbonate ions induced depression."

Jan 1, 2003

By John Ralston, Jonas Addai-Mensah, Patience Mpofu

The flocculation and dewatering behaviour of kaolinite (non swelling) and smectite (swelling) clay dispersions has been investigated using hydrolysable metal ions Mn(II) and Ca(II) and anionic polyacrylamide-acrylate copolymer (PAM) at pH 7.5 and 10.5. A pH-dependent, specific metal ion adsorption behaviour, accompanied by a marked reduction in particle zeta potential and slurry shear yield stress, was observed to have a profound influence on the colloid stability of both types of clays. Due to the differences in the cation exchange capacity, the smectite clay dispersion required a higher amount of metal ions than kaolinite dispersion to produce similar effects. The adsorption density of the anionic PAM at the negatively charged clay particle surfaces correlated well with metal ion hydrolysis and adsorption behaviour, all of which had a strong effect on slurry settling rate and extent of consolidation. At pH 7.5 where Mn(II) ions hydrolyse, metal ion and flocculant adsorption densities were both greater in the presence of Mn(II) than Ca(II) ions. At pH 10.5, however, where Ca(II) ions begins to hydrolyse, higher adsorption densities were observed for Ca(II) ions in comparison with Mn(II) ions, as the latter hydrolysed completely and precipitated. The metal ion mediated flocculant adsorption led to improved hydrogen bond driven particle bridging and facilitated charge neutralisation flocculation mechanisms which significantly enhanced the dewaterability of both clay dispersions.

Jan 1, 2003

By Chris A. Bennett, Glenn S. Dobby, David A. Bulled

Establishing reagent dosing strategies for new ore bodies has traditionally involved a combination of experience and empirical experimentation using standard laboratory tests. The grade and recovery data resulting from these lab tests have historically been used as direct indicators of plant performance despite the obvious differences between the flotation environments. A reagent scheme selected in this way would subsequently be employed to generate the grade and recovery information for the geometallurgical model which in turn was used for metal production and cash flow forecasts. If the reagent scheme was sub-optimal then so too would be the forecasts and the resulting cash flow.

Jan 1, 2003

By Jan J. Cilliers, Nicolas Barbian, Esther Ventura-Medina

"Mineral froth flotation is one of the most widely used processes to separate particles of valuable mineral from its associated gangue. It involves the selective separation of the hydrophobic particles from the slurry into the froth. The hydrophobic particles attach to the air bubbles and rise up to the froth phase on top of the slurry. The valuable mineral is collected when the froth overflows the cell wall. The separation performance of the process can be linked to the amount of solids and valuable material loaded on the bubble shells. In addition, it is well known that in most mineral systems, the presence of solids can enhance the stability of the froths. How the solids get to be distributed and what proportion is actually attached and stabilising the bubbles is not well known.This study aims to establish the relationship between operational variables, solids loading on bubbles and flotation performance. For this purpose, a series of industrial experiments to sample the solids in the bubble films under different operational conditions were carried out in two copper concentrators under steady state conditions. Samples of the lamellae were taken by touching the top surface of the bubbles with a glass slide. The amount of solids and liquid per unit area in the bubble lamellae can subsequently be estimated gravimetrically and by image analysis. The grade of the attached particles was also measured by adequate sampling. This gives an indication of the maximum grade that could be achieved from the process under the operating conditions."

Jan 1, 2003

By Sun Chuanyao, Jia Muxin

Generally, if the bond valence (BV) between metal ion and oxygen of the mineral is greater than 0.8, only surface species –Me-O-H or –Me-O exposures on the mineral interface, if the BV is between 0.2-0.8, the metal ion exposures on the interface, and if the BV is less than 0.2 the metal ion dissolves into water. The PZCs of oxide minerals and island silicate minerals are determined by the bond valence of the bond in the mineral crystals, the higher the bond valence the lower the PZC of the mineral. So the PZC sequence of Al2SiO5 minerals is kyanite> andalusite> sillimanite. The general rule for framework silicate minerals is as: The higher the Al content, the lower the PZC of the mineral, when the ratio of Al to Si in the tetrahedron skeleton is below 1:3. The higher the Al content, the higher the PZC of the mineral, when the ratio of Al to Si in the skeleton is between 1:3 and 1:1. The general rule for layer silicate minerals is summarized as: the three-layer silicate minerals have much lower PZCs than that of the two-layer silicate minerals. The threelayer silicate mineral with the octahedron layer occupied by lower charged cations has lower PZC than that of the three-layer silicate mineral with the octahedron layer occupied by higher charged cations. The twolayer silicate mineral with the octahedron layer occupied by lower charged cations has higher PZC than that of the two-layer silicate mineral with the octahedron layer occupied by higher charged cations. The layer silicate mineral with Al substitution in the tetrahedron layer has lower PZC than that of the layer silicate mineral without Al substitution in the tetrahedron layer. Such pyroxene minerals whose M1 is occupied by a trivalence cation and the M2 is occupied by a monovalence cation has lower PZCs than those both M1 and M2 are all occupied by bivalence cations. Such hornblende minerals whose M2 is occupied by a trivalence cation and the M4 is occupied by a monovalence cation has lower PZCs than those both M2 and M4 are all occupied by bivalence cations. There is no Si4+ or 4 coordinated Al3+ exposures on the surface of framework silicate minerals, the metal ions of three layer or chain silicate minerals are compact between tetrahedron layersor chains, they hinder the metal ions to interact with oleate acid radical, the metal ion octahedron layer exposures on the surface of a two layer silicate mineral, but the the oleate acid radical can not attach to a metal ion by replacing a –OH- that connects three metal cations in the same time, So the floatability of such silicate mineral is bad. The metal octahedron chain style of an island silicate mineral affects it floatability, the mineral exposures octahedron chain metals with two dangling bonds in two directions floats better than the mineral exposures octahedron chain metals with two dangling bonds in one direction.

Jan 1, 2003

By P. N. Mohan Das, K. Harikrishna Bhat

"The major ilmenite reserves are located in India at Chavara (CH), Manavalakurichi ( MK) and Chatrapur, Orissa (OR). India stands first in terms of ilmenite reserves, which are estimated to be 278 million tonnes out of which, 142 million tonnes are processable. Mineralo-chemical analysis showed that Chavara ilmenite is the most weathered one with about 60% TiO2 while Chatrapur is the least weathered with about 50% TiO2. XRD and SEM studies of different magnetic fractions of these three mineral deposits established the co-existence of ilmenite with pseudorutile, rutile and haematite phases in substantially varying amounts. It is observed that the tropical weathering rather than the source rock difference has apparently played an important role in imparting major compositional and structural dissimilarities among the ilmenites in different places. Further, the chemical analysis, XRD and SEM characterisation of differently weathered samples of MK ilmenite separated by the magnetic fractionation showed that the degree of alteration was invariably associated with the decrease in magnetism, increase in the rutile phase and the change in Fe2+/Fe3+ ratio of ilmenite grains. Magnetically separated fractions when subjected to metallisation with carbonaceous reductant such as coke showed that the degree of reduction increases with the degree of alteration and with the decrease in the Fe2+/Fe3+ ratio.In the processing of ilmenite through the Becher process, aeration rusting of pre - reduced ilmenite is found to be the rate-limiting step thus, affecting the productivity and economy of the process. Investigations have proved that the addition of some organic compounds such as glyoxal, sucrose etc., to the system accelerates the reaction to such an extent that the rusting time has been reduced to less than half. The formation of acids by the these organic compounds during the rusting reaction was proved responsible for maintaining the pH of the solution in the range 3-4 at which iron hydroxide do not precipitate and block the pores in the reacting surface of the grain."

Jan 1, 2003

By Kal Sastry, Anshuman Prasad

"Agglomeration of fine iron ore concentrates is carried out in two steps:Balling, which refers to the production of green pellets by tumbling moist fines powders in drums, discs, or cones, and Induration, which refers to the subsequent thermal treatment of the green pellets in straight grate or grate-kiln systems.This paper addresses computer simulation of balling or green pelletization step. The process of agglomeration from a mechanistic point of view can be described as the transformation of moist feed to well-formed species or pellets. The moist feed is composed of fines of infinitesimal size while well-formed species are of finite size and number. These well-formed species undergo changes in their size and number through different mechanisms of agglomerate formation and growth. Nucleation, coalescence and layering are the three main mechanisms that describe the formation and growth of granules during an agglomeration process. A population balance equation enables quantitative description of the evolution of agglomerate size distribution due to the occurrence of each of the mechanisms.A numerical solution for the population balance model is necessary and is obtained by the use of a sizediscretization approach. The numerical solutions provide a suitable basis for the analysis of the agglomeration process. Also a coalescence kernel has been introduced that is capable of describing the simultaneous occurrence of nucleation, coalescence and layering mechanisms. The effect of feed moisture has been described using a moisture factor with an exponential functional dependence on the moisture content. The effect of the feed to seed ratio is modelled by the introduction of a crowding factor. It was assumed that only the feed particles which are much more in number experience a crowding or restricted in space interactions effect. A computer simulation program has been developed with MATLAB as the simulation language."

Jan 1, 2003

By Rebecca Hope, Derick Moolman, Frikkie Malan

"Despite the lip service that has been paid to pro-active plant maintenance processes over recent years, a significant portion of maintenance in industry is still reactive. The business driving force to prevent expensive production opportunity costs arising from “break-down maintenance” is obvious. Various benefits can be derived from successfully deploying remote equipment diagnosis technology and associated business processes.From an end-client’s viewpoint these include the ability to predict and take actions to prevent equipment breakdowns, increasing the lifetime of equipment by responding to appropriate operating instructions and therefore improving the return on capital expenditure. Better planning and scheduling of maintenance priorities and resources with performance measures like an Equipment Health Index are also possible. The knowledge that a qualified supplier engineer is constantly in touch with the operating conditions of their equipment, albeit remotely, is more than a comfort, and can be translated into quantifiable cost savings and improved supplier service levels."

Jan 1, 2003

By Paul W. Weiblen, Louis J. Cabri, Rolando Lastra

"Preliminary tests were done to determine whether comminution by electric-pulse disaggregation, or EPD (cf. Rudashevsky et al; 1995), was more effective than using conventional crushing for Merensky Reef ore. A hand sample of the Merensky Reef was sawn in two: then one sub-sample was comminuted to – 2 mm using E-PD at the University of Minnesota, and the other sub-sample was crushed to –2 mm using a conventional jaw crusher at CANMET.The products of the electric-pulse disaggregation and jaw crusher were fractionated by sieving and by a separation using a heavy liquid with a specific gravity of 3.3, because the proportion of platinum-group minerals (PGM) and sulphides to silicate minerals is very low. Thus, four mineral separates were produced: –2000 + 833 µm, -833 +208 µm, -208-µm float and -208-µm sink. All the mineral separates were studied by image analysis (Lastra et al; 1998). The main objective was to determine the liberation of gangue (silicate minerals), chromite, pyrrhotite, chalcopyrite, pentlandite and PGM. In the case of the PGM, a specific image analysis program was written to search and measure these minerals."

Jan 1, 2003

By Wang Xiaotie, Yu Yongfu, Che Liping, Zhang Fuguang

The flotation process of native Rare Earth minerals such as bastnasite, monazite, mixed minerals of bastnasite and monazite, using the new effective collector Dh was studied in this paper, respectively, and the flotation properties are described. The good qualities of the new collector Dh were revealed through comparing with other collector of Rare Earth minerals. The test results of different ore samples show that at moderate pulp pH (8.5-9.5), Rare earth minerals can be effectively separated from barium, calcium and silicon bearing intergrowth minerals (barite, calcite and silicate minerals) and high quality Rare Earth concentrates can be obtained successfully by the new collector Dh, acid silica gel, turpentine and reagents fitting together rationally. In order to determine optimum technical conditions, the effect of pulp pH, pulp temperature, pulp density and the effect of dosage of reagents (Dh and acid silica gel) on the flotation were investigated in the test.

Jan 1, 2003

By G. Demi, G. Belardi, N. Shehu, S. Cico

The physico-chemical interaction between minerals such as olivine, chromite and serpentine and the ions most commonly present in solution, like Ca and Mg and flotation reagents such as EDTA and oleic acid was investigated. The study was conducted via release tests, electrophoretic measurements and microflotation of selected minerals coming from the Kukes deposit (Albania).

Jan 1, 2003

By Victor Avdokhin, lvan Kovlekov

"Studies of the process of concentration of gold-containing sands and technogenic resources show that the main reason of gold losses is misbalance between size of gold particles and degree of roughness of mineral bed. This results in free circulation of small gold particles in pores with following washing off the particles from the bed by turbulent flows.We elaborated design of magnetic sluice, intended for improving efficiency of recovering fine gold by optimizing magnetic field of a magnetic system on the base of forming catching coat from magnetic mineralsThe magnetic sluice includes trough-shaped body from magnetic-conducting material. On the bottom of the trough, magnets are placed, and opposite poles of the magnets are oriented outwards. Thickness of the bottom is determined to be sufficient for locking magnetic lines of force of the magnets on each other. The magnets of rectangular plate shape are placed on the rough bottom, covering the whole surface or with spare areas; the magnets are placed across the trough with alteration of rows with the same pole orientation."

Jan 1, 2003

By Chris A. Fleming

"Interest in the recovery of cyanide from gold and silver plant tailings has heightened in recent years. This interest has been spurred by several factors:Increasingly stringent regulations throughout the gold producing world, governing discharge limits for free and total cyanide to tailings ponds and the environment.The increasing cost of active chemical treatment versus passive (natural degradation) treatment of tailing, to bring them in line with environmental regulations.The worldwide trend to processing of more complex gold ore bodies, which is usually accompanied by higher levels of cyanide consumptions and greater concentrations of cyanide (particularly the copper cyanide complex) in tailings.The growing negative perception of the general public for the gold mining industry, due to several highly publicized cyanide spills in recent years (breaches of tailings dams, accidents involving trucks carrying cyanide to gold plants, etc.).The ability to recover cyanide from gold plant tailings has been known almost as long as the cyanidation process has been practiced, but there has been little incentive to process tailings in this way in the past. With the development of technologies that make it possible to recover and recycle free or complexed cyanide directly from gold plant slurry tailings, which indicates, on paper at least, the potential for significant cost savings compared to cyanide destruction, coupled with the introduction of legislation to seriously limit the discharge of cyanide to the environment in most gold-producing regions of the world, many companies are evaluating the cyanide-recovery alternative."

Jan 1, 2003

By J. H. Starkey

SAGDesignTM Testing for grinding mill design was introduced commercially in 2004. Up to January 2008, 18 projects have been completed and 99 samples have been tested using this method. Two papers have been published describing the patented test procedure and one of these shows how the results compare with other grinding test methods. This paper will briefly discuss the theory on which this technology is based, and explain the procedures used to develop the calibration equation. Case studies are also included to demonstrate the effectiveness of the test work being done. These case studies show how the SAGDesign test is being used today: to design new grinding circuits for commercial full scale use; to calculate throughput in existing mills for production planning; and to accurately define grinding mill requirements at the scoping, pre-feasibility or feasibility study stage of project development, in order to economically identify the size and cost of the grinding mills that will be needed for the project. This is important because if the full rec-ommended SAGDesign testing program is done at an early stage in the project, the definitive cost for a guaranteed throughput, grinding mill design (by Outotec if their mills are purchased) is available. New grinding mill design for final engineering will be represented by the test work done on the Climax Molybdenum Project for Phelps Dodge (now FMI) in Colorado, USA. The SAG mill and ball mill for Climax are now in fabrication with project start up in late 2009. Next, the sizing of grinding mills at the scoping, pre-feasibility or feasibility study stage of mine development will be represented by a large metal mining property in Russia. Finally, calculation of the throughput for existing mills will be represented by work done at a base metal mine, in eastern Canada. Test work for designing SAG mills is now done in four laboratories at the time this paper was written. One in the USA at Dawson Metallurgical Laboratories, Inc. in Salt Lake City, two in Russia at the TOMS Research and Design Institute and at the Irgiredmet Research Institute, both in Irkutsk, and a fourth mill has been installed in Australia at AMMTEC Limited?s lab in Perth. A fifth SAGDesign test mill for radioactive ores has been built by Starkey & Associates, specifically for testing uranium ores and can be moved to any licensed lab in the world on a project basis.

Jan 1, 2014

By S. C. Borah

Graphite, a mineral form of pure carbon, is one of the most versatile minerals in industry, because of its varying physical properties and characteristics. The mineral occurs naturally in the form of tubular crystals or microcrystalline earthy lumps, or it is disseminated in rocks, which have undergone intense metamorphism. India has a large deposition of graphite minerals out of which about 43% are found in Arunachal Pradesh. However, compared to the rest of the country, the North-East Region and particularly Arunachal Pradesh has not attracted attention till date for detail investigation for characterization, beneficiation, prospecting and/or exploitation of the mineral resources including graphite. Bulk graphite sample were collected from upper Subanshiri district of Arunachal Pradesh. Chemical analysis of the representative samples were carried out and found that 7.29%, 19.60% and 6.07% of fixed carbon (FC) is present in graphite sample collected from La-Lamdak, Bopi and Taliha, Arunachal Pradesh, respectively. Chemical analysis of the ash of the graphite sample shows presence of impurities such as silica, Al2O3, Fe2O3, Ca, Mg etc in the graphite sample which are also supported by XRD and SEM-EDX investigation. The graphite samples of Arunachal Pradesh are low grade and do not fulfill the market requirement for the industrial applications. Therefore, low-grade graphite is subjected to beneficiation for the upgradation of the graphite for industrial applications. We have adopted the dispersion?cum-settling technique for the beneficiation of the graphite sample collected from Arunachal Pradesh. The FC of 40.21% with 41.17% raw graphite recovery which is equivalent to 71.02% carbon recovery have been obtained by gravity separation technique using only distilled water without any chemical reagent in case of graphite sample collected from Bopi, Arunachal Pradesh. The graphite sample is upgraded up to 47.75% FC with 41.91% raw graphite recovery, which is equivalent to 85.85% carbon recovery with the pH adjustment at 9 with NaOH. Keywords: graphite, beneficiation, gravity separation, arunachal Pradesh

Sep 1, 2012

By David Verrelli, Melissa Kistner, Leanne Smith, Chris Aldrich, Lidia Auret, Warren Bruckard

In this investigation, different mixtures of realgar and orpiment particles were floated in a laboratory batch flotation cell and multivariate image analysis was used to estimate the arsenic content in the froths. The analysis was based on the froth colour, as well as extraction of three groups of textural features, namely those based on grey level co-occurrence matrices (GLCMs), wavelets and local binary patterns (LBPs). Collectively, these features provided better information on the arsenic content of the froths than any one of the individual groups of features. Partial least squares models could explain approximately 78% of the variance in the arsenic by using all the features combined. The colour content, particularly the green component in the red-green-blue (RGB) features, provided almost as much information as each of the three sets of texture-base features individually.

Jan 1, 2014

By J. A. Sweet

The issues facing graduate training in the mineral processing industry are not too different today from those that prompted the initiation of the Anglo American Platinum Graduate Development Programme (AGDP) in 2002. Graduate metallurgists in South Africa enter the industry from different undergraduate programmes at various tertiary institutions, and so the knowledge and skills of the young graduates varies. Further, the geographical expansion of the industry combined with the downsizing of business units means that there are fewer opportunities for young graduates to be mentored through their first few years on site. Anglo American Platinum chose to address these issues by implementing an intensive, structured graduate training programme for all their new metallurgical graduates, known as the AGDP. The first two years of experience of the AGDP, from the viewpoints of both graduates and lecturers, were presented to the mineral processing community at the IMPC in Turkey in 2006 (Sweet et al, 2006). From the beginning, the programme was structured in a modular fashion to include a basic technical ?toolbox? including statistics, the scientific method and sampling protocols, while the mineral processing content comprised advanced learning in comminution, classification and flotation (later extended to include hydrometallurgy). Technical communication ? both written and verbal ? was included from the start. The programme was focussed very strongly on site work (?learning by doing?), with a major integrated site campaign conducted and analysed by each cohort. In 2012 the AGDP will accept its ninth cohort into the programme. This paper describes how Anglo American Platinum and the University of Cape Town have developed and adapted the programme over the last few years, in response to the challenges of the global recession, skills retention, and the changing operational needs of the company. The programme, which was drawn up to accommodate around 15 concentrator-only graduates, now accommodates 35-40 concentrator, smelter and refinery graduates annually. The programme has also been modified to facilitate new graduates spending most of their first year on the operations. The benefits of the programme for Anglo American Platinum have been tangible, and will be discussed in the paper. Keywords: graduate training, technology transfer

Sep 1, 2012

By M. Kadiyski, V. Stoyanova, E. Visariev, V. Stoilov

"The present study deals with copper losses in slag from copper smelting. Copper slag cooling at Aurubis Bulgaria is traditionally done in pits. A new type of slag-cooling is introduced in the site, involving cooling ladles. In a previous study, the ladle cooling process was studied in detail, showing an improvement in the recovery of copper in the slag after flotation. The main reason for better recovery of copper is the increased cooling time, which allows for the accumulation and aggregation of copper droplets. The effects of the newly introduced slag cooling process are studied using optical microscopy and scanning electron microscopy. Cooling in pits and in ladles is compared, based on copper droplet size, distribution and content. Specialized image processing software is employed on images taken with an optical microscope. The results are then compared with a similar technique, available in SEM software. The availability of phase-analysing image software in combination with electron dispersive X-ray spectroscopy makes it possible to study the morphological properties, distribution and chemical composition of the copper droplets. The obtained results confirm the initial conclusions about size, distribution and composition of the copper-bearing particles. A large amount of copper particles is examined showing an obvious increase in their size from pit- to ladle cooling. The results show an increase in the average size of the droplets, which doubles from pit-cooling to ladle-cooling. There is a well-pronounced tendency of decrease of the percentage of droplets in the smallest fraction (<5 µm) in the ladle-cooled slag. In addition, the number of droplets in the larger fractions increases, compared to the ones in the pit-cooled slags. It is believed, that the developed methodology for analysis provides a relatively quick and reliable solution for comparison of the cooling rates in the slag. INTRODUCTION In the process of copper smelting and converting, iron-silicate slags are produced that contain various amounts of dissolved and entrained copper. Different physical and chemical techniques are employed for the valorisation of the remaining metals in the slag – magnetic separation, leaching, roasting, flotation, etc. According to Gorai et al (2003), about 2.2 tons of slag is produced per ton of metal. In 2016, about 20 million tons of copper have been produced globally (www.icsg.org). At an average of 0.5 percent copper content after treatment, these slags contain more than two hundred thousand tons of copper which is lost due to inefficient processing."

Jan 1, 2018

By Yuhua Wang, Haitao Zheng, Guangli Zhu, Yuehao Zhao, Fushun Yu, Dongfang Lu

"Spodumene, feldspar and quartz possess similar surface properties, which make the difficult to separate spodumene from other silicate minerals by flotation. The differences of crystal structure, surface property and floatability of three minerals were studied by various technical means. The results show that Li-O and Al-O bonds in spodumene structure are not strong and easy to be broken. However, Al-O and Si-O bonds in feldspar and Si-O bond in quartz are very strong and not easy to be broken. High contents of Al and Li on spodumene surface were found by XPS measurements, which is benefit for the adsorption of anionic collector. The surface energies of main cleavage planes of spodumene (110), feldspar (001) and quartz (001) are 1.88 J/m2, 2.97J/m2 and 2.68J/m2, respectively. Hence, the exposed surfaces of feldspar and quartz are not saturated and easy to adsorb OH- ions from solution and cause the lower IEP than spodumene. The contact angles of three minerals in water are lower than 16º, suggesting that the hydrophilicity of three minerals is high, and the order of hydrophilicity is quartz > feldspar >spodumene. Correspondingly, contact angles and flotation recoveries of spodumene are bigger than that of feldspar and quartz in presence of a combined anionic and cationic collector named YOA.INTRODUCTION Flotation technology plays most important role for the recovery of spodumene from pegmatite ore. Generally, spodumene with fresh surface is easy to be floated using soap and oleic acid as collector, and the best flotation pH range is 4.0 to 9.0. However, the flotability of spodumene will become worse when its surface was polluted by slime which produced by the weathering of spodumene and other silicates (Dresler et al. 1998; Moon and Fuerstenau 2003; Menéndez et al. 2004; Yu et al. 2015). In addition, the species of Ca2+, Fe3+, Mg2+ and other metal ions in pulp can not only activate the flotation of spodumene, but also the activation of gangue minerals, and then the flotation selectivity of spodumene from gangue minerals became wores (Wang and Yu 2007; Yu et al. 2014). In order to eliminate the negative effects of slime and metal ions on the flotation of spoddumene, the desliming and long time scrubbing with the addition of NaOH and Na2CO3 were adopted. Usually, NaOH shows the activation for spodumene flotation, and the recovery of spodumene increases with the increase of NaOH dosage. Na2CO3 can eliminate the non selective activation of Ca2+, Fe3+, Mg2+ ions in the pulp, and the concentrate grade of spodumene increases with the increase of Na2CO3 dosage. Anionic collectors such as chelants, hydroxamic acid, oxidized paraffin soap, naphthenic acid and oleic acid were widely used for the flotation of spodumene (Dresler et al. 1998; Moon and Fuerstenau 2003; Menéndez et al. 2004; Yu et al. 2015)."

Jan 1, 2018