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By L. Gutierrez, M. Jeldres, R. J. Jeldres

"Clays are present in a large number of mineral deposits and are commonly found as gangue. Its complex chemical structure, characterised by anisotropic surfaces, makes its presence a permanent challenge for flotation operations, increasing the reagent consumption, decreasing the quality of the concentrate, and changing the rheological properties of the system. In this context, the main objective of this research is to improve the floatability of chalcopyrite minerals in the presence of clays by using guar gum, a low molecular weight organic polymer, which acts as a surface coating agent for clays. Clay Minerals Society provided the kaolinite sample and the chalcopyrite sample was purified from mineralized rock specimens obtained from Ward’s Natural Science Establishment. Micro flotation tests were carried out in a 150 cm3 Partridge-Smith cell, using compressed air as the gas phase at a flow rate of 80 cm3/min. Potassium amyl xanthate (PAX) and methyl isobutyl carbinol (MIBC) were used as a collector and a frother, respectively. The results showed that the use of guar gum improves the recovery of chalcopyrite in the presence of kaolinite because it induces the formation of clay aggregates that settle by gravitational effects, preventing the 'coating effect' and decreasing excessive collector consumption. pH played a key role in the guar gum performance, which was most effective at highly alkaline conditions (pH 11), where the copper recovery improved from 73% to 90%. The work has significant implications for the mineral flotation in the presence of clay minerals.INTRODUCTION The mining industry is continuously confronted with challenges that alert the sustainability of the sector. There is little availability of water, the grade of the deposits are getting smaller, and the gangue is becoming more complex. Usually, clays are part of the gangue in numerous systems, including copper ore, porphyry, nickel, platinum, etc. (Senior & Thomas, 2005). The structure is mainly composed of layers of tetrahedral silica (T) and octahedral alumina (O) that join in certain proportions: 1: 1 (T-O) and 2: 1 (T-O-T) (Theng, 2012). Also, they expose two crystallographically different surfaces: the faces, which tend to be negatively charged, and the edges, which carry a charge that changes from positive to negative depending on the pH (Van Olphen, 1977). One of the most common clays in copper deposits is kaolinite, whose structure is composed of an octahedral sheet of gibbsite bound to a tetrahedral silica sheet in the ratio 1:1"

Jan 1, 2018

By Philippe De Donato, Odile Barres, Mukendi Kongolo, Stoyan Gaydardzhiev, David Bastin, Jean-Marie Kanda

The adsorption patterns of potassium amylxanthate on the surface of high purity malachite subjected to prior sulfidization with NaSH have been followed and elucidated. DRIFTS spectroscopy has been used to trace the associated physicochemical alterations as well as the chemical species present on the mineral surface. Varying the collector concentration from 5.10-4 to 1.10-2 mol/L has led to different degree of surface coverage of the alkyl groups and to formation of organometallic hydrophobic complexes of CuX or CuX - X2 type. The results reveal that the CuX complex formed on the malachite surface without sulfidizing agent is more unstable and prone to dissolution-precipitation phenomena. Based upon the constructed adsorption isotherms and upon the degree of statistical coverage, different zones of mineral-reagent interactions could be distinguished. They correspond respectively to the monolayer, bi-layer and tridimensional condensation domains. In each of the identified zones mono or double layer adsorption patterns of the collector are proposed leading respectively to formation of surface compounds with different degree of hydrophobicity. The results suggest that sulfidisation remains an important prerequisite in view achieving efficient flotation of the malachite from the studied copper ore.

Jan 1, 2014

By Jorge Rubio, Gabriel Berkowitz, Fabiano Capponim, Carlos Perez Guerrero, Elves Matiolo, Denise G. Nunes

This paper describes some advances in flotation research in fines (“F” 38 to 13 µm) and ultrafines (“UF” < 13 µm) mineral recovery by two different techniques, at laboratory scale. Extender flotation and flotation with .multi-bubbles. (bubbles with a wide size distribution) of copper sulphide fines (ore feed of about 1 % Cu) were compared with a .standardised. mill laboratory procedure. Comparative evaluation was made through concentrate grade and recovery (size by size results included), .true. (bubbles-particles attachment only) flotation recoveries and process kinetics. Both techniques yielded higher metallurgical efficiencies than the mill standard but better results were obtained with the extender flotation, with emulsified diesel oil (90 gt-1). Concentrate recoveries were of the order of 85-90 % (84 % in standard conditions), 14-17 % Cu grade (15 % Cu in the standard) and 3.5-4.5 min-1 for the Klimpel rate constant (3 min-1 in the standard). Size by size and true flotation results proved that metallurgical and kinetic gains, obtained with the two techniques, might be attributed to fines and ultrafines enhancement. Data obtained are discussed in terms of physical and physico-chemical parameters related to aggregation and capture (of particles by bubbles) phenomena and the practical potential of these techniques are envisaged.

Jan 1, 2003

By T. Leißner

This contribution deals with the mineral processing of Li-silicate greisen-type ores comprising of quartz, topaz and zinnwaldite (lithium-rich mica). The origin of the greisen-type ores processed is the Ore Mountains(Germany) where it is explored as a potential resource for the production of lithium carbonate. The goal is to develop a process chain for the enrichment of zinnwaldite using dry techniques only. As basis for the investigation the process chain, which historically was used to process the greisen focused on cassiterite and wolframite, is taken and modified towards the zinnwaldite. Starting with crushed material with particle sizes smaller than 35 millimeters, investigations on different approaches to grinding to liberate mica from gangue are carried out. Concentrates of zinnwaldite are then produced by magnetic separation of size fractions. To assess the success of grinding, classification and separation, mineral liberation analysis and atomic absorption spectroscopy are used. The amount of lithium measured in the sample with atomic absorption spectroscopy was used to calculate the content of zinnwaldite based on its known mineral chemistry. Combined with the particle size distributions, product qualities are determined. Altogether, this allows the thorough evaluation of the success of comminution with focus on following steps of concentration. Keywords: lithium, zinnwaldite, magnetic separation, mineral liberation analysis

Sep 1, 2012

By John Ralston, Jona 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 C. H. Zhou

Cryogenic grinding of Printed Circuit Board will bring less pollution, reduce energy costs, smaller particles, regular particle size, efficient process, separation various materials due to different fracture toughness. Systemic studies of recycling discarded Printed Circuit Board (PCB) by low-temperature modification and cryogenic grinding have been made in this paper. Firstly test mechanical property of PCB at different low-temperature, including impact strength, flexural strength, and shear strength. Do experiment on the power consumption of different cooling temperature, The results show that the average power consumption is lower between -30? to -60? and the average power is decrease in evidence at -30?. Use ZKB type double roll shear crusher to crush PCB to 20mm×20mm particle size, in a temperature range of -10 ~ -30? Used R type mill to grind sample to minus 3mm under different working condition, the average power consumption is decrease in evidence from -10 ? to -30 ?, power consumption is the lest at rotational speed is 1180rpm.

Jan 1, 2014

By D. J. Borrow, K. van Netten

"A fine coal tailings feed was selectively agglomerated using a concentrated water in oil emulsion binder consisting of 95% aqueous phase and 5% organic phase. The purpose of the study was to investigate a continuous system in plug flow, providing a rapid beneficiation technique with high selectivity and recovery. The development of the novel binder was undertaken in previous work in a batch system consisting of a high-speed blender. In this previous work, it was found that agglomeration could be achieved in 3 s, providing the binder was pre-dispersed. Furthermore, it was found that, depending on the feed, only ~1 wt% of oil was required to achieve agglomeration, some 10 times less than required in traditional oil agglomeration. In a more recent study, the technique was adapted into a continuous process. Due to the rapid speed of the process using the emulsion binder it was found that a simple flow constriction within a 1 inch pipe was sufficient to achieve the selective agglomeration observed in the batch system. In this previous study, a coal feed consisting of a flotation product was agglomerated at a superficial slurry velocity of 1.3 m/s using a partially closed ball valve as the flow constriction. In the current study, a feed consisting of fine coal tailings with an ash content of 50.1% was used to establish the influence of superficial slurry velocity on the agglomeration process. The superficial slurry velocity was varied between 1.3- 4.2 m/s, while maintaining a constant pressure drop of 100 kPa across the flow constriction. The flow constriction consisted of a partially closed ball valve. It was found that increasing the superficial slurry velocity across the flow constriction reduced the amount of organic liquid required to achieve agglomeration. Under the optimum conditions, a combustible recovery of 80.4% was achieved at a product ash content of 9.6%. This work demonstrates a valuable product can be rapidly produced from tailings material using the novel emulsion binder. INTRODUCTION A significant opportunity exists to recover fine coal from material that is currently classified as waste. This waste material, also called tailings, is currently considered not economic to process due to its high ash content, low solids concentration, and the fine size of the particles. Thus, for this opportunity to be realised, a process is required that is highly selective and has the ability to economically recover fine particles at high throughputs. The technique of oil agglomeration has previously been considered as a candidate for the recovery of fine coal, as it is highly selective and has no lower limit on the size of particle that can be recovered (Capes and Jonasson, 1989). However, the cost of the oil required as the binding agent in the process has proven to be a significant barrier to any long-term applications (Swanson, Nicol, and Bensley, 1977). Recently, however, Yoon and co-workers have developed an ultrafine coal separation process that utilizes an oil phase for the recovery of the hydrophobic coal particles and have implemented an oil recycle to greatly reduce the consumption and thus cost of the oil (Yoon et al., 2016)."

Jan 1, 2018

By John C. Gathje, Rick Moritz, Wilhelm de Beer

"Froth flotation has a long history of success for the recovery and concentration of a wide variety of minerals of commercial interest. Both the art and science of flotation have progressed greatly, and as our knowledge has increased so has our ability to improve mineral separations and recoveries.One area of interest in recent years has been the flotation of refractory gold ores to recover the gold-bearing sulfides. In many instances, the use of conventional air flotation to concentrate these values has achieved only limited success. However, as a result of intensive research, Newmont Mining has expanded the boundaries of flotation, and it can now be used to successfully treat many gold-bearing sulfide ores as well as platinum and palladium ores. This has been achieved through the use of the N2TEC technology, which utilizes nitrogen as an inert gas in the flotation process.Laboratory and pilot plant investigations and a commercial plant have proven its worth. Compared to air, the patented N2TEC process has increased the gold recoveries of many ores by 5 to 15 percentage points, and improvements of an even greater magnitude have been observed. This paper describes the process development for the flotation plant now being operated at Newmont’s Lone Tree Mine located in Nevada, as well as development work that was done on ores from their Twin Creeks Mine also located in Nevada."

Jan 1, 2003

By A. Gülmez

The complex ore deposit containing fluorite, barite and bastnaesite minerals is located in Beylikova Region of Sivrihisar town of Eskisehir Province of Turkey. The ore contains 40.80% CaF2; 35.35% BaSO4; 2.01%Ce; 1.5% La; 0.39% Nd and 0.1% Th. Barite recovery from this ore by flotation of the HCl leached tailings is presented in this paper. Rare earths are recovered by leaching. The leached residue (tailings) containing fluorite and barite is subjected to froth flotation to recover barite. The effect of pH and collector concentration on the flotation of barite have been studied in this work.

Sep 1, 2012

By Pawel Strzalkowski, Marta Baszczynska, Urszula Kazmierczak

The paper presents issues related to interference of mining activities with the environment. Exploitation of mineral resources causes primarily a modification of the landscape. All of the negative impacts on environment are short-lived and last as much as it takes to exploit the raw material. After the mine closure reclamation is necessary during which all aspects that reduce harmful effects of the mining activities on the environment must be taken into account. Current ways of reclamation allow recreating natural environment, which is different from the original and enriched in diverse new values. This requires propositions of new forms of converted land development through a detailed analysis of technical, natural, planning, economic and social sphere requirements. Before making final decisions regarding selection of direction of reclamation, a thorough analysis of the key factors has to be carried out. All steps related to the implementation of the reclamation project are shown in the paper using Limestone Mine "Górazdze" located in the south-western part of Poland as an example. This paper also presents an analysis of current ways of post-mining reclamation towards agricultural and forestry landscape, along with our own suggestion for their extension in order to preserve biodiversity. For choosing optimal solutions the most relevant criteria were considered: existing natural values and possibility of their protection. Taking into account the economic and social aspects, supported by natural potentials, implementation of tourism and recreation in this area were proposed. It was shown that this proposition would not interfere with the current trends of the natural landscaping. Finally, after completion of reclamation and land development in the considered mine area, creation of a geo-park was proposed along with appearance of geotourism in the area. To illustrate the proposed forms of post-mining land development in the form of maps, an ArcGIS(ESRI) software was used.

Jan 1, 2014

By J. Bouchard, Ali Vazirizadeh, R. del Villar

"The amount of water reporting to the concentrate correlates well with the solid entrainment. It is well known that the frother and collector dosage as well as the froth depth and gas rate influence the amount of water reporting to the concentrate. This is also true for gas dispersion properties such as gas holdup and bubble surface area flux. On the other hand, a positive bias rate, required to reduce hydraulic entrainment, also affects water recovery and thus the particle recovered by entrainment (depending on the their size). Up until now, the effect of the gas rate on the water recovery has been studied, but no comprehensive investigation on the gas holdup, bubble size and bubble surface area flux has yet been reported. This research precisely aims at addressing this issue. The experimental work was carried out under a constant gas flow rate to eliminate the gas volume effect, while other gas dispersion properties have been varied by modifying the frother concentration and the shearing water introduced to the frit-and-sleeve sparger. A constant froth depth and no wash water were used, in order to be able to evaluate the exclusive correlation between the water recovery and the bubble surface area flux and/or the bubble size. It is worth mentioning, that the particle size of the hydrophobic particles did not show a significant effect on the amount of water going to the concentrate. Not surprisingly, experimental results demonstrate that water recovery increases with the bubble surface area flux and with the gas hold-up."

Jan 1, 2014

By S. Narra

Converting biomass into valuable fuel requires various preprocessing of the raw materials. Biomass densification is one of the conversion processes for its utilization. The aim of densification is to produce biomass pellets, which can withstand regular handling stresses and exhibit high densities with uniform size and shape. Physical properties, such as the particle size distribution after comminution is of highest importance for the binding mechanisms in the pelletisation process. Durability and strength of the pellets play an important role indicating the ability to withstand handling stresses. Particle size distributions of the cereal straws (Rye and Wheat) after specific comminution and liberation processes have been carried out with the help of three different image analysis (Microscope, Camsizer and Fibreshape). The durability of the pellets have been investigated as specified in the standards (ASAE standard S269.4) with a quadratic crate and the strength of the pellets with compression and tension testing machine (Zwick Roell type: ZMART.PRO). The particles size results showed differences in both length and width after different comminution processing. An exact comparison between the particle size analyses with the three different image analyses was not possible. The particle size distribution and the different comminution processes displayed influences on the durability and strength of the produced pellets. The particle size distribution displayed approximately 40 % of fines and 60 % of fibers. The particle size distribution displayed a direct relation to the durability of the pellets. Further durability and strength of the pellets displayed a good correlation.

Sep 1, 2012

By R. K. Dwari

The electrostatic beneficiation of coal is based on tribocharging characteristics of ash forming minerals and coal particles. The tribocharging of quartz, pyrite and coal particles contacted with various metals and polymeric materials have been measured and the charge acquisition is assessed through surface energy calculations from liquid contact angle data. The contact angles, before and after tribocharging of solids, are measured using Krüss tensiometer and Washburn?s method where the sample holders in tensiometer are specially constructed with tribocharger materials. The charge polarity and amount of charge acquired by quartz, pyrite and carbon with metal tribochargers were found in good agreement with the reported work functions of the contacting surfaces. The charge results with polymer materials differed from the work function values, presumably caused by surface contamination. The surface energy of quartz calculated by all the theoretical approaches in the literature showed that the tribocharging increases the surface energy. Both polar and non-polar components computed from Fowkes and Owens-Wendt-Rabel-Kaelble approaches dis-play that both these components increased after triboelectrification. However, the polar component divided into acid and base components, as in van Oss approach, manifest decreasing acid part and increasing base part. Since quartz charged negatively during tribocharging with metal surfaces and therefore accepted electrons, the determined acid and base surface energy components are consistent with charge transfer process. The results also elucidate an explicit correlation between the charges generated by powders and the surface acceptor (acid) and donor (base) electronic states and thereby the work functions. A novel fluidized bed tribocharger was designed and developed with internal baffle system for efficient contact electrification of mineral and maceral to produce high differential charging for efficient separation. The results achieved on coal with 45% ash content are presented and discussed.

Jan 1, 2014

By Tong Guan, Guangqin Fu, Lihong Deng, Xiaotong Zhou

The raw ore contains many kinds of valuable metal elements. It is rich in valuable metal elements, such as Pb, Zn, Sb, Sn, Ag and is associated with S,Fe,As,In,Cd. A new technology which includes medium intensity magnetic separation, preferential lead flotation, zinc-sulfur bulk flotation, zinc-sulfur flotation separation, tin gravity separation and tin slime flotation was chosen to recover valuable minerals in the raw ore, and the iron concentrate, the lead concentrate, the zinc concentrate, the sulfur concentrate and the tin concentrate can be obtained. To the zinc-sulfur bulk concentrate with the grade of 7.21%Zn and 16.97%As acquired by the zinc-sulfur bulk flotation, two different flowsheets of Zn-S separation technology are chosen to study. The lab test shows that when using lime+DM as depressor, the zinc concentrate assaying 47.73%Zn with the recovery of 95.01% can be obtained and the test indexes are better than that of the flowsheet which using lime as depressor. At the same time, the Cd content is 0.65% and the In content is 0.10% in the zinc concentrate, so they all reach the smelting comprehensive recovery standards and the As content decreases to 0.23%. Finally the flotation separation of christophite and As-bearing sulfide minerals can be successfully realized.

Jan 1, 2014

By D. Gucbilmez

Three spiral concentrators having different geometries were compared in a chromite processing plant. They had different diameters, helix-cross sections and capacities. Two of the spiral concentrators were manufactured in China and one of them was manufactured in Australia. The tests were carried out in a closed circuit experimental setup by using a low grade chromite ore. The pulp densities kept the same during the operation, and the samples were taken simultaneously. The effects of the different positions of the splitters on separation and the feed rate were the parameters that were observed during the experiments. The performances of three spiral concentrators were found to be different. To clarify the effect of the particle size on the separation in spiral concentrators, the screening was applied to the feed. The samples were sieved from 75µm. The test results indicated that the separation performance decreased dramatically in very fine particles. Although fine particles caused some problems in spiral concentrators, fine grinding is required for this particular chromite ore for better liberation. A suitable method for the fine particles should be investigated for acceptable recovery.

Sep 1, 2012

In looking to the future of mineral processing the focus is typically on improved processing units. Basically it is a search for an elusive wonder machine that could revolutionise the economy of mining: the sorter that strips 50% of the ore with only a few % loss of value; the comminution device that uses 5% of the energy while producing fully liberated particles; or the recovery device capable of producing a 99% recovery at 99% grade. These aspirations are propounded against a reality backdrop of sorters rusting in back yards, mill throughputs below design and varying by 30%, cyclones flaring and cut-sizes fluctuating, mediocre recoveries and soaring processing costs. This disconnect between aspiration and reality appears, to these authors at least, to be a mighty chasm. Moreover, it remains one over which we are expected to magically leap rather than methodically bridge. Indeed one may be forgiven for thinking that should such a wonder machine come along, taking advantage of it would be highly improbable. Questions would inevitably emerge on how to feed the correct material, how to cope with the wide variability of feeds, how to control such advanced equipment and how to handle the new product from such a machine. It is likely these questions might lie unanswered, or more regrettably, unasked. It is generally accepted that as an industry we are exceedingly unlikely to teleport from the current status quo to an entirely new reality in a single flash. It is our thesis that the probability of these magical machines materialising is remote, and even if they miraculously appeared, we simply wouldn?t know what to do with them. Rather, it is our contention, that a step change will only arise through a staircase rather than from a single giant leap. We should focus on building those steps and linking them together into a firm structure ? a workable mineral processing circuit. This paper addresses the alternative of a coherent set of modest but significant improvements, integrated to produce the step change we desire: essentially, a reduction of processing energy to below 40%, which we believe is achievable without recourse to any mystical machines. A key underlying capability to designing these dramatically improved processes, is the weaving of independent process models into a coherent circuit simulation, in order to design the new generation of mineral processing circuits. Keywords: step change, circuit design, circuit simulation, energy reduction

Sep 1, 2012

By Junwei Han, Kai Xue, Wenqing Qin, Tan Xu, Fen Jiao, Lianbing Cai, Wei Liu

"The research aimed at solving the problem of the stacked spent magnesia-chrome refractories using in non-ferrous metal smelters, which contain various heavy metals and are considered as a hazardous waste. The purpose of the research is to recycle the spent refractories environmentally and economically using gravity separation and flotation to obtain metal concentrates for smelting and using chloridizing volatilization to remove the trace metals from tailings, providing raw material to reprocess magnesia-chrome refractories. In the course of the study, laboratory techniques for the preparation of experimental samples of spent magnesia-chrome refractories were developed including the sequence of operations of material grinding, gravity separation, tails regrinding, flotation, filtration and subsequent unification of concentrates, filtration and chloridizing volatilization of tails, and collection of volatiles. Laboratory tests carried out on several types of samples of spent magnesia-chrome refractories from different smelters showed that gravity separation provided increase in quality of concentrates including about 80% metals (including Ag, Pb, Bi) and flotation separation provided increase in recovery of concentrates under the condition of 200g/t of emulsified kerosene, and 500g/t of combined collector. Based on combined technology of gravity and flotation separation, about 90% metals were recovered from the refractories by a closed-circuit test and the total concentrates contained 40% metals, which can be returned to smelting process as a feeding. Because a small amount of metal in raw materials will seriously affect the performance of refractories, chloridizing volatilization is necessary for removing the remaining 10% metals from tails mixed 8% coke and 13% magnesium chloride at a temperature of 1200°C. Thus, the tailings can be reused as a raw material for new refractories.INTRODUCTION Magnesia-chrome refractory has been used extensively in various industries such as secondary metallurgy, non-ferrous furnaces and cement making due to their high temperature stability, low thermal expansion and outstanding erosion-corrosion performance at high temperatures (Gotod et al., 2005; Vezza et al., 1997; Gregurek et al., 2015). Generally, the magnesia-chrome refractories are produced from a mixture of magnesia and massive variety of chrome ores. However, massive chrome ores are being depleted throughout the world. Even more serious is that the heavy metal chromium (Cr) can transfer into soil and water, which will have an influence on the survival and development of human beings (Zhao et al., 2006; Jiang et al., 2004; Qintie et al., 2013). As a result, regulations treating spent magnesia-chrome refractories as potentially hazardous waste are being enforced, making their disposal difficult and expensive."

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

By Paulo Sérgio de Oliveira, Joaquim D. Donda, Andreia C. Rosa

"The search for energy efficient technologies for comminution processes is constant in mineral processing studies, since those processes represent a major percentage of operational costs. In this context the use of stirred mills is increasing, especially for ultrafine grinding. Although many authors claim that these new equipment are more efficient than the conventional ball mills, there were very little chances to prove that in a practical way, since there are few industrial circuits where those technologies perform the same duty. Therefore, the regrinding circuit of Germano second concentrator offers an interesting opportunity: a vertical mill operating in parallel with two ball mills. During almost two years of operation, several sampling campaigns were conducted to evaluate the vertical mill performance and to compare the operational data of the three mills. The industrial data was also compared to jar mill tests results, which are monthly conducted in Samarco labs in order to predict the specific energy consumption required by the ore fed to these circuits. The vertical mill demonstrated the same ability to achieve the product specifications of the ball mills while proved to be able to reduce the medium specific energy consumption in about 40%."

Jan 1, 2014

By Chanki Jeong, Heechan Cho

In this study, batch flotation experiments were conducted to recover rare earth elements (REE) from an REE ore deposit in the Mushgai Khudag area, Mongolia. Apatite was found to be the major REE mineral while monazite and xenomite were observed as minor minerals. The main purpose was to float apatite to increase the REE content. Oleic acid was used as collector and MIBC was used as frother. Sodium silicate was used as a depressant for iron compounds. NaOH was used to adjust the pH of the flotation to about 9.5~10.0. The particle size was 90% less than 152 ?m (- 100 mesh). The content of REE elements was analysed by ICP - OES to determine the contents of REE such as Ce, La, Nd, Pr and Y. When sodium silicate was used, the best result was obtained using 0.2 mL of sodium silicate, 2 mL of oleic acid and 2 mL of MIBC. Under these conditions, the recovery of REE was about 78% and the grade of the first froth product was 42,995 ppm Ce, 24,088 ppm La, 14,236 ppm Nd, 4,388 ppm Pr and 1,570 ppm Y. When conducting flotation after iron minerals were removed by magnetic separation, a better result was obtained; with 2 mL of oleic acid, 2 mL of MIBC and no sodium silicate, the recovery was increased to 90% and the grade was also increased to 58,600 ppm Ce, 28,624 ppm La, 17,160 ppm Nd, 5,348 ppm Pr and 1,971 ppm Y.

Jan 1, 2014