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By S. Q. Zhu

A newly developed coal flotation collector ZFC and its flotation characteristics for five different coals were introduced in this paper. ZFC is an emulsion composed of 27% diesel oil, 70% water and 3% surfactants. The main surfactant is synthesized with oil which is environmental favorable and reproducible. Compared flotation experiments show that, at the same dosage, ZFC give 2%~5% recovery promotion than typical collector with only a slightly ash content increment, but saving 70% diesel oil. Zeta-potential and Wetting heat measurement indicate that the surfactant helps the interactions between oil and coal particles, the industrial application tests in several coal preparation plants demonstrate that ZFC is suitable both in technical and economical aspects.

Jan 1, 2014

By Ralph J. Holmes, Victor Sharp, Steven J. Spencer, Kevin J. Davey, Jonathan J. Campbell, Peter L. Phillips, David G. Barker

"Improved measurement tools for monitoring and control of AG/SAG mill performance have a high level of interest in industry. Historically, acoustic emission monitoring has been widely used on SAG/AG/ball mills and hydrocyclones to provide new information on the conditions inside these devices affecting their performance. The current work was focused on a new technique using surface vibration monitoring of a number of pilot-scale and production-scale AG/SAG mills to yield insights into the events occurring in the mills. The development of relationships between signal analysis outputs and mill operating conditions can be used for soft-sensor measurement of mill process variables. The technique used an array of accelerometers mounted on the mill lifter bolts linked to a fast data acquisition system which monitored the surface waves generated during operation. Details of the system are presented. Mill operating variables were adjusted systematically to provide a wide range of operating conditions for surface vibration signal collection. The experimental approach is discussed.The signals acquired during the experiments were analysed using a range of techniques. The results show that strong relationships exist between measured vibration power (both total power and within certain frequency bands) and mill load level/power and mill speed. A new method for extraction of power spectral density and band power information on features of interest in a mill rotation cycle is also presented.These results show that single sensor analysis information from the surface vibration system can be used as soft sensor inputs for monitoring process variables such as mill load that until now, have not been reliably measured. System outputs also show considerable promise in the area of condition monitoring. An example of the signal analysis output is presented showing elevated vibration levels in an area with higher resultant wear. Eventually, it is considered that outputs from this system for process variable and wear condition monitoring will be key new inputs to an online AG/SAG mill monitoring and control system."

Jan 1, 2003

By David Morrow

Fly ash is a by-product from coal-fired power stations that is captured from the exhaust gas stream by electrostatic precipitators (ESPs) or bag houses. It is mainly derived from the inorganic components in coal but also contains residual carbon from unburnt fuel (measured as LOI). In the past, nearly all fly ash was sent to landfills or tailings ponds by power generators but this trend is quickly changing due to landfill costs, sustainability requirements and the inherent value in correctly processed fly ash. The main property that makes fly ash suitable for recycling is its use as a pozzolan. Pozzolans exhibit cementitious properties that make them suitable for partial cement replacement, and that can have beneficial properties for concrete mix designs. Fly ash can be used to replace up to a third of the of the Ordinary Portland Cement (OPC) requirement. Suitable fly ash nearly always requires the removal of the less reactive coarser fraction from the finer fraction. Due to the pozzolanic nature of fly ash, it must be processed dry and separation is normally required at 45 micron. In response to the increasing demand from a range of dry classification applications, Metso purchased an established air classification technology suitable for both mining and construction applications. The classifiers intelligent design efficiently utilizes the air flow which keeps power requirements low whilst including a scrubbing/recirculating function within the classifier that allows extremely efficient separations even at very fine sizes. This technology is of global interest to Fly Ash processors, but should be of particular interest in India which is both the second largest cement producer in the world as well as producing 80% of its power from thermal sources. This paper is intended to give a brief overview of fly ash and requirements for use as a pozzolan, air classification of fly ash and a case study from an established and experienced fly ash producer. Keywords: air classifier, fly ash, pozzolan, fineness, cement, cholla, salt river materials group

Sep 1, 2012

By M. Wright, A. H. Mwale

Opportunities to promote enhanced eco-efficiency (i.e. the simultaneous improvement in economic and environmental performance) for the minerals industry exist across the whole value chain. However, given the current operational models of major companies within the industry, and their focus on refining of primary ore bodies, it is important to understand where such opportunities might lie within minerals beneficiation, as it is here that major environmental pressures are felt. This paper examines the combination of unit technologies in a minerals beneficiation train, and explores the inter-relationship between energy input and water consumption for a given mineralogy and product recovery, as these are two critical environmental issues which affect the overall viability of many minerals plants. In particular, we review constitutive relationships for each of the sub-processes of comminution, flotation, and tailings dewatering, and suggest how these might be integrated into a unified hybrid model, with particle size distribution as the key design variable. Such a model can then be used to explore the trade-offs between different performance objectives (be these technical, economic or environmental) as part of a multiple-objectives optimisation exercise. In this way, it may become practical to envision situations in which concentrate grade and recovery are sacrificed, marginally, in order to reduce energy demand in comminution, and improve overall water recovery. In addition, this work provides a useful baseline against which to analyse the potential for dry processing. This becomes more relevant as the industry commits to advancing the sustainable development agenda in the face of the increasing life -cycle costs and impacts of minerals processing operations, coupled to declining ore body grades, and the desire to maximise recovery of minor and trace elements. Some specific observations for copper are offered, supported by operational data from Zambian copper mines.

Jan 1, 2003

By T. Kumaresan

The Bayer process used for refining bauxite to smelting grade Alumina serves as the linchpin of the Aluminum production industry worldwide. Even though the process is well established, the presence of impurities in the liquor affects the quality of product and imposes a major economic cost on the industry. This review article focuses on the issues pertaining to Gibbsitic (Al2O3.3H2O) precipitation circuit. The comprehensive review provides a basic understanding of the aluminum trihydrate precipitation and agglomeration phenomena. Crystal growth rate and agglomeration play a significant role in determining the output PSD of agglomerates. Hence, the effect of certain thermodynamic and hydrodynamic parameters along with the impact of impurities (oxalates, aldols, acids etc.) and additives on hydrate growth has been reviewed.

Sep 1, 2012

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 Jingzhong Kuang, Zheyu Huang, Chuanzhou Guo, Pengfei Liu

"In this paper, scheelite and scheelite coated with Pb2+ (SC) were synthesized by chemical precipitation with the help of ultrasonic. The role of the Pb2+ on scheelite was evaluated. Additionally, the dissolution behavior of minerals and the adsorption mechanism of collectors were investigated systematically via SEM, XRD, EDS. The results indicate that the ultrasonic cavitation can promote the formation of scheelite with large particle size and high crystallinity. Due to the exchange of WO4 2- and OH-, the dissolution of scheelite are not in a 1:1 equivalent amount by chemical formula and the concentration of WO4 2- is higher than that of Ca2+ in the solution because Pb2+ promotes the transfer of WO4 2- from scheelite surface into the solution. The dissolution of scheelite is an endothermic reaction and its enthalpy reaches the maximum value of 692.59J·mol-1 at pH=8~10. But the coating of Pb2+ changes the thermal effect of scheelite in the solution and the dissolution of SC is an exothermic reaction with the dissolution enthalpy of -262.30 J·mol-1. At pH=8~10, the adsorption capacity of sodium oleate and salicylhydroxamic acid on the surface of SC is higher than that of scheelite which delivers that Pb2+ contributes to the scheelite surface dissolution and enhances the adsorption of collectors on the mineral surface, thus achieving activation.INTRODUCTIONIn modern society, tungsten is a type of quite important rare metal and also a strategic resource. Because of its low vapor pressure, high melting point, good electrical and thermal conductivity properties, it is widely applied in high-temperature technology, lighting, machine and engine construction (Zhao,Z.W, 2013; Yan, W, 2017; Ilhan, S, 2013). Both scheelite and wolframite are the major tungsten deposits. With the depletion of easily-processed wolframite, scheelite has drawn a great deal of scientific and industrial attention. Scheelite can be recovered by flotation due to the metathesis of polarity and chargeability on minerals surface via adding regulators and collectors."

Jan 1, 2018

By V. V. Lvov, L. S. Chitalov

"The purpose of the research is intensification of physico-mechanical ore properties determination for ball grinding processes in comminution circuits. The research presents comparative studies aimed at intensification of Bond Ball Mill Work Index (BWi) determination, such as testing technique of Ahmadi and Shahsavari, Berry and Bruse, Gharehgheshlagh, Horst and Bassarear, Kapur, Magdalinovich. The subject of the research is a test procedure of apatite-nepheline, copper-nickel, gold-sulfide and iron ores for the Bond ball mill index. The Bond Ball Mill Work Index for the material firstly was determined by standard Bond test methodology. Two the most promising testing techniques - Ahmadi and Kapur testing techniques - were modified. For the Ahmadi technique it was proposed to pay attention to the circulating load, which should be stabilized on the value of 250% as fast as possible. Two methods were put forward to quicker stabilize the circulating load. For the Kapur technique it was proposed to use empirical coefficients, which is determined especially for the apatite-nepheline, copper-nickel, gold-sulfide and ores. The modified Ahmadi and Kapur techniques require no more than two cycles of ball grinding to determine BWi (while normally 6-8 cycles are required) and less than 5 kg of initial feed. The suggested modified Ahmadi and Kapur techniques allow to intensify the physico-mechanical ore properties determination for ball grinding processes and BWi test costs considerably, which makes them useful for mass sampling and monitoring strength properties of ores entering a concentrating mill. INTRODUCTION When designing concentrating mills, the choice of the technological scheme for ore pretreatment, particularly the type, quantity and size of the main process environment, the determination of optimal grinding conditions and the calculation of equipment load are carried out by preliminary studies of grinding in semi-industrial or laboratory-scale plants. Semi-industrial tests on full-scale plants provide the most reliable information for calculating specific loads for equipment. However, this requires a significant amount of ore samples, a high labor costs and the pilot plants. Thence the most researchers performed grinding tests with small laboratory equipment using small ore samples."

Jan 1, 2018

By F. Q. Cheng

Despite the successful industrial practice to recovery KCl by flotation, the adsorption state of collectors at KCl salt surfaces is still not fully understood. In this paper, the captive bubble contact angle measurements at KCl and NaCl crystal surfaces in their saturated solutions are reported. The influence of different collectors and their concentration are considered. The results show that both cationic and anionic collectors produce a hydrophobic state at the structure breaking KCl salt sur-face, with finite contact angle values of between 30o and 40o. In contrast, the contact angle at the structure making NaCl salt surface is zero at all collector concentrations, suggesting that no collec-tor adsorption occurs, a supposition that is supported by results from molecular dynamics simulation (MDS). Further, it appears that the presence of surface defects such as edges and corners promote the adsorption of collectors at the KCl surface, and that the flotation is achieved by bubble attachment at the edges/corners of KCl particles with the formation of aeroflocs.

Jan 1, 2014

By Jurgens J. Louw, Vincent C. Smith, Gareth C. Smith, Agit Singh, Dave G. Hulbert

"The flexibility of the PlantStar control platform has enabled Mintek to investigate and easily develop new control strategies for both milling and flotation. This includes a Solids Feed Controller, a Safety Limit Controller, Mill Power Optimiser and Flotation Optimiser, amongst others.The solids feed controller was developed for minerals processing plants using a specialised time delay compensator. Using conventional time delay compensators that are purely model based, results in robustness problems due to model uncertainties. The Mintek Solid Feeds Controller makes use of a plant model, but compensates for model inaccuracies, giving more controller stability and a more robust delay compensation algorithm.The safety limit controller has been developed to switch smoothly between normal and safety control loops without bumping the process. The safety loop output is chosen in accordance with a predefined list of priorities and whether the respective constraint boundaries are exceeded.The Mill Power Optimiser helps to find the power peak on the mill power curve. This insures maximum grind with maximum throughput. It also prevents power dips due to mill overloads, making the milling circuit easier to operate.The flotation optimiser algorithm analyses trends of all accessible variables in the process. The algorithm uses this information to calculate operating conditions that will control the residence times, mass pulls and circulating loads within a flotation circuit to a specified setpoint. Research is being done to now optimise these setpoints in order to achieve better recovery."

Jan 1, 2003

By R. C. Dunne

As ore grades of existing and new ore deposits continue to decrease there is ever increasing pressure to decrease operating costs to maintain profitabitabitiy at existing mine sites and for new projects. The accepted solution to this dilemma in most cases is to increase treatment rate, leading to a coarser grind, at the expense of marginal decreases in recovery. The recovery loss is usually associated with losses of liberated and composite coarse material. This paper will review the practice of coarse particle flotation, including the reagent chemistry, cell hydrodynamics, froth stability, entrainment and flotation cell design, all parameters important to the recovery of coarse liberated and composite particles. This will provide a better understanding of opportunities to improve the recovery of coarse particles. Some examples will be provided.

Sep 1, 2012

By Ali Dehghani Ahmad Abady

In Sarcheshmeh Copper Complex, a molybdenite floatation concentrate was produced by selective removal of copper impurities with 7 stages of cleaner floatation banks, that contains around 1% copper and 54.5% molybdenum. Mineralogical studies, physical and chemical characterizations showed that the sample contained 91% molybdenite (MoS2), 2.6% chalcopyrite (CuFeS2), 0.2%Covellite (CuS), 1.6% pyrite (FeS2) and 4.6% other nonmetallic impurities. In the present study, the removal of the copper sulfide was investigated by ferric chloride leaching for achieving a molybdenite concentrate with copper content less than 0.3%. Therefore, the application of response surface methodology (RSM) for modeling and optimization of the influence of three control parameters including ferric chloride (FeCl3) dosage, reaction temperature and reaction time, each varying in five levels, were considered, and the mathematical model for prediction of %Cu removal from molybdenite concentrate was derived. This study showed that RSM could effectively be applied for the modeling of ferric chloride leaching, and finding an economical optimum condition to achieve maximum de-coppering efficiency while consuming minimum leaching reagents. The optimum dissolution conditions to maximize Cu extraction were 200 kg/t for ferric chloride dosage, 120 min for reaction time and 80 °C for reaction temperature with a prediction of 83.20% Cu dissolution. Keywords: molybdenite concentrate, ferric chloride, leaching, response surface methodology (RSM)

Sep 1, 2012

By R. S. C. Smart

Surface chemical factors, including the balance of hydrophobic (e.g. collectors) and hydrophilic (e.g. oxidation products, precipitates) species, are major control determinants in flotation rates of specific minerals and therefore grade and recovery. There are a number of challenges involved with the surface analysis of different mineral phases from process streams in a flotation facility. The first is to collect samples that are representative of the process and retain their surface chemistry prior to introduction into the instrument. The second challenge in studying the surface chemistry of specific minerals is to find reliable methods of mineral phase recognition. In surface analysis of mineral particles, confident mineral selection can be difficult with many multi-metal minerals and with precipitated, adsorbed, reacted and contaminant species in the outermost molecular layers. The third challenge is to provide a statistical surface analysis of multiple grains of the same mineral. Methods to achieve these aims are described. Principal component analysis (PCA) of ToF-SIMS data provides improvement in phase recognition, particle selection and associated variations in surface species. Specific examples from both lab and plant operations, demonstrate that this technique can be utilized to differentiate surface chemical factors promoting (hydrophobic species) or inhibiting (hydrophilic species) flotation. A study of copper ion transfer (inadvertent activation) from chalcopyrite to pyrite and sphalerite clearly identified a statistical difference in copper intensities between the sphalerite and pyrite phases corresponding to their flotation response. The PCA analysis applied to concentrate and tails samples collected from the Inco Matte Concentrator demonstrated extensive CuOH and NiOH transfer between chalcocite and heazlewoodite minerals. The statistical analysis has been able to identify mechanisms controlling recovery and selectivity. High intensity conditioning (HIC) tests in which sphalerite was separated from a complex sulfide ore gave a 5% increase in the overall Zn recovery. The PCA/ToF-SIMS statistical analysis revealed the discriminating depressant action of adherent aluminosilicate (gangue) fine particles and adsorbed ions on the surface of sphalerite grains. HIC conditioning resulted in the removal of these gangue fines improving surface collector attachment efficiency.

Jan 1, 2014

By Pradip, Beena Rai

A molecular modeling study was carried out on an adsorbed oleate monolayer on the surfaces of three calcium minerals, fluorite, calcite and fluorapatite using Universal Force Field (UFF) potentials. The cleavage plane of calcite {104} was the best template for oleate monolayer adsorbed since the surface structure enabled all the calcium sites available on the surface to be occupied by oleate anions. The area occupied per chain of oleate in this well packed monolayer was computed to be 20.2 Å, which exactly matches the value calculated to be the parking area per oleate molecule for a fully packed monolayer based on strictly geometric calculations. On the other hand, the precentage of calcium sites occupied by oleate to achieve a fully packed monolayer in case of fluroite and and fluorapatite was found to be 67% and 75% respectively. The results of this theoretical study suggest that while all the three adsorption conformations, that is unidentate, bidentate and bridging type are equally likely on fluorite and fluorapatite, bridging is most likely on calcite. Interestingly, all the conformations are observed experimentally for calcite-oleate system also. The reasons for this discrepancy between the theoretical predictions and experimental observations are not clear. More work is required to resolve this discrepancy, in particular simulation studies in presence of solvent water molecules on the surface.

Jan 1, 2003

By Y. H. Tang

For its surface features, micro-sized hematite is usually difficult to recover by magnetic separation; especially, the existing high gradient magnetic separator in industry can not utilize collecting matrix with thin silky rods for its property of being easily blocked; the lower size limit for recovery of micro-sized weak magnetic minerals is about 0.019mm, some even is 0.037mm. This paper introduces the application of the combined new technique of water-air joint discharging of concentrate and collecting matrix with different diameter silky rods in the field of recovery of micro-sized hematite by high gradient magnetic separator. The commercial test result for recovery of a certain hematite with size about ?0.037mm shows that the recovery can be promoted by 16.81% with basically same concentrate grade.

Jan 1, 2014

By D. Moradkhani

Copper metal has important role in the basic industrials, as if it did not exist, modern human life would not develop! Copper leaching, as the first step, is important step in copper production processes. In this research, efficient factors on the leaching have been investigated. For this reason, four efficient factors on leaching namely pH, liquid to solid ratio (L/S), temperature and time, as independent variables, were optimized using response surface (RSM) with D-optimal. A quadratic equation was used to create response and contours. According to the results from analysis of variance (ANOVA), the value of determination coefficient (R2=96.77%) indicates that the model was good fit. Optimum experiment condition also was found: pH of 1, L/S of 8.24, temperature of 26.06 ? and time of 43.64 min. At this condition, the maximum recovery of copper was equaled to 92/38 in which good desirability achieved.

Sep 1, 2012

By Hamid-Reza Manouchehri

"The triboelectric charge attributes of feldspar, quartz and wollastonite minerals, after contacting different triboecharging medium made of different materials, were considered. Their charge acquisitions by different size fractions of minerals were monitored and accordingly their energetic work function values were estimated. Moreover the separation behaviours of these minerals through the electric field of a laboratory free falling separator were determined and the effects of some chemical reagents on separation their separation characteristics were studied.Finally an attempt was made to translate the findings from single mineral systems to a complex silicate ore, containing quartz, feldspars, wollastonite and some other silicates. The results show favourable prospect to apply the triboelectric separation technique for beneficiation such a complex raw material."

Jan 1, 2003

By H. R. Manouchehri

"In all electrical beneficiation methods, the difference in electro-physical properties of the contributed mineral particles, essentially frictional charge, electrical conductivity and dielectric constant properties are exploited to achieve separation. The composition of the raw material determines what kind of either corona charging, conductive induction, or triboelectric separation method should be employed. The process is versatile and is influenced by different parameters related to mineral characteristics, surrounding ambient conditions and electrical and mechanical attributions of the separating device. Electrical separation is surface based beneficiation method which is mainly affected by the surface and surface changes of the minerals. Therefore, it is essential to understand how the electrophysical properties of the minerals can be changed/modified. During electrical/electrostatic separation process, both charge magnitude and its polarity that developed on the particles and therefore, their electrical beneficiation potential is essentially defined by surface phenomena. Therefore, it is essential to understand how the main electro-physical parameters can be changed/modified with applied surface treatment/pretreatment methods to promote separation. Surface treatment of minerals is carried out by different means, including chemical conditioning, irradiation, thermal treatment, etc. This paper discusses and analyze the electrical separation process, electrophysical properties of the minerals with special focus on the effect of surface pretreatment/treatment methods to affect electrical beneficiation potential of the minerals. The surface treatment methods vary in a wide range from simple surface cleaning to more complicated chemical conditioning and doping. The knowledge of the solid-state physics and chemistry leads to improve the beneficiation potential of different mineral systems by choosing suitable treatment method(s). Despite the complexity and multiplicity of the charging mechanisms, difficulties in separating fines it seems to be beneficial make our attempts to further investigate and develop the process as dry, low cost beneficiation process, especially nowadays when environmental concerns, as well as energy and water consumptions are main concerns for mining industry."

Jan 1, 2018

By Carina Ulsen

The existing construction and demolition (C and D) waste recycling technologies and standards have been essentially focused on the production and use of coarse recycled aggregates. Very few papers focus on the production of recycled sand, although some previous results show that fine aggregates fraction represents around 40 to 60% (in mass) of the Brazilian waste and it is usually used as road sub-base or disposed in landfills. The quality of the recycled aggregate is strictly related to the content of porous and low strength phases, mainly the patches of cement remaining on recycled aggregate surface. Some technologies have already been described in the literature, even though, to the moment none of these technologies has clearly succeeded in reaching the large market available. This paper presents a summary of the main properties of the sand produced from C and D waste by tertiary crushing at vertical shaft impact crusher (VSI). Additionally mineral processing technologies were applied on the attained product, such as gravity concentration by shaking table and spirals and removal of cement paste by attrition. The main properties of recycled sand are discussed and compared to the previous C and D waste, respectively: particle size distribution, particle shape, chemical composition, cement paste content and porosity. The results demonstrates that the crushing allowed producing a VSI-sand with low porosity and water absorption due to the increasing on the content of silicates from natural rock phases and increasing liberation between these phases and porous cement paste; the particles from the attained product presented also a better shape (sphericity and aspect ratio). The attrition tests assayed on VSI recycled fine aggregates accomplished a further selective disaggregation of cement paste and other porous materials - the porosity was reduced from 10% to 7%. The concentration by shaking table at narrow sieve fractions led to a product with low porosity and reduced content of cement paste, however, concentration on spirals did not succeed since separation was performed essentially by the size of the particles. The heavy product from shaking table represented almost 75% in weight and has less than 60% recovery of CaO+LOI, and expressive reduction on porosity. The aim of producing sand from construction and demolition waste through mineral processing unit operations changes the recycling approach and contributes for up cycling the recycled sand. The exhaustion of sand deposits on Brazilian large centers, the increasing price and the construction boom encourages the development of alternative materials as construction raw material. Keywords: recycled sand, construction and demolition waste, technological characterization

Sep 1, 2012

Hydrofluoric acid (HF) is traditionally used in plant operation to separate feldspars from quartz. It acts during the conditioning step as a pH regulator and an activating agent providing an excellent selectivity. However, a corrosive chemical environment and the ecological impacts from the potential fluoride ion contamination are limiting factors to use this chemical agent at an industrial scale. Investigations of the amine-feldspar interactions in the absence and presence of non-linear long-chain alcohols were carried out on two ore samples. The presence of alcohol molecules led to form a closed packed layer only on the surface of feldspars. The highest order and packing at the feldspar surface were observed with a particular alkyl chain structure as Guerbert alcohols. A new flotation process was developed and tested at both lab and pilot scales on different feldspar ores. The Guerbert alcohols allow to perform a feldspar concentrate with very low content in quartz (2.3-3.5 %) and feldspars recovery from 78 to 81 % while the aliphatic isoalcohols show a more higher recovery level (88-89 %). New HF-free process is strongly dependent on the pH range (1.7-2.5) and sulphuric acid consumption during conditioning steps. Optimal amine/alcohol weight ratio is ranged between 0.8 and 1.0. The values below 0.8 decrease strongly the flotation selectivity and the quartz recovery within the feldspar concentrates is higher than that occurs with HF.

Sep 1, 2012