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By Adam Jordens, Olga Kuzmina, Christopher Marion, Kristian Waters

"In order to meet the growing demand for non-Chinese rare earth suppliers many new rare earth (RE) mineral deposits are currently under development, however these deposits typically include many minerals for which there is little processing information available. One of these deposits is the Nechalacho deposit located in the North West Territories of Canada. This deposit contains multiple RE minerals including bastnäsite, zircon, fergusonite, allanite and monazite. The work presented here investigates the use of different classes of flotation collectors (carboxylic acids, hydroxamic acids, phosphoric acids) typically used in RE mineral flotation to float the Nechalacho ore directly. Flotation tests are also conducted as the final step in a beneficiation process incorporating centrifugal gravity concentration and magnetic separation. This combination of centrifugal gravity concentration and magnetic separation rejects low specific gravity gangue minerals such as K-feldspar and plagioclase and concentrates high specific gravity minerals such as magnetite and hematite. The removal of low specific gravity gangue helps to improve flotation and the removal of ferromagnetic iron oxides is important prior to flotation using certain chelating collectors."

Jan 1, 2014

By L. Li

Chemical composition, mineral composition, and iron occurrence state of main mineral are studied, Research of mineral processing technology is carried out according to ore features. The test results indicate, that through staged grinding-staged concentration process, the better separation index is up to 65.54%, iron preparation concentrate grade and 85.66% recovery with the fineness (-200 mesh) 45.88% in the primary grinding ore and the fineness (-200 mesh) 75.50%, in secondary grinding ore in the situation of best magnetic field intensity (roughing 0.2T and cleaning 0.15T).

Sep 1, 2012

By P. Huang

Chitosan was tested as a depressant in the differential flotation separation of chalcopyrite and galena. The micro-flotation results showed that chitosan selectively depressed chalcopyrite while galena was floated by potassium ethyl xanthate in acidic solutions. With the addition of 0.67 mg/L chitosan (CT) in the slurry of chalcopyrite-galena mixtures at pH 4, the recovery of galena was 95% while that of chalcopyrite was 30%, indicating that chitosan could potentially be used in differential Cu-Pb sulfide separation. Furthermore, the study of chitosan with either low (LCT) or high molecular weight (HCT) in the differential flotation indicated that better separation was achieved by the chitosan with lower molecular weight (LCT). ToF-SIMS was employed to study the distribution of CT on the surface of chalcopyrite-galena mixtures by ion mass spectra analysis and surface imaging, which showed that CT adsorbed heavily on chalcopyrite but barely adsorbed on galena. The positive ion ToF-SIMS spectra provided information on the surface composition of chalcopyrite-galena mixtures after CT treatment. It appears that the selective adsorption of CT on chalcopyrite was originated from the strong interaction between NH3+ and Cu. Keywords: differential flotation, micro-flotation

Sep 1, 2012

By W. H. Cheung

Nickel (Ni) plays a major role in the production of steel and other major alloys. There are two sources of Ni: laterite and sulphide ores. Global reserves of sulphide ores are being rapidly depleted, while there are enormous reserves of Ni laterite, much of it in Australia. As well as being present in huge amounts, Ni laterites have the advantage of containing cobalt (Co), a valuable mineral. Over the past decade, these factors have been driving the industry to explore the processing of Ni laterite. A route that has been used commercially in processing nickel laterite ore involves the thermal activation of the minerals by pre-reduction followed by ammoniacal leaching (Caron). Although this process has been effective in processing the goethite rich laterite minerals, the higher-grade serpentine-based minerals have been shown to be less susceptible to this process. This has been attributed to the formation of inert olivine phases. In this study, we examined the use of an alternative lixiviant, sulphuric acid, in leaching pre-reduced limonite and weathered saprolite nickel laterite ores. The specific aim of this study was to examine the sulphuric acid leaching of Ni and Co from pre-reduced laterite minerals, and to understand the role of mineral transformations in this metal dissolution. Synchrotron based X-ray diffraction was used to examine the transformation of goethite (FeOOH) to spinels and serpentine mineral ((Mg,Fe)3Si2O5(OH)4) to olivine. Reduction tests were carried out using CO and CO2 reducing gas mixtures and temperatures from 400 °C to 700 °C. The rate of formation and disappearance of specific Bragg peaks during reduction of specific minerals were used to derive an understanding of these solid-state reactions. Laboratory based reduction tests and leaching in sulphuric acid were used to validate the effect of these mineral transformations. The results suggest the versatility of sulphuric acid in leaching nickel from spinels and olivine, which was achieved at the expense of lower selectivity. Cobalt dissolution was found to be dependent on the nature of ferro-cobalt alloy formed during reduction.

Jan 1, 2014

By Rong Fan, Andrea Gerson

"The small recovery of Ag, often in the order of 50%, by traditional flotation and leaching process strategies is closely related to the complicated and heterogeneous nature of Ag-bearing minerals with Ag typically being associated with numerous minerals within any given ore-body. Moreover, grain sizes may be extremely fine with micron-scale common. In order to design cost-effective Ag-bearing mineral flotation and leach recovery strategies it is firstly necessary to characterise the speciation of Ag and its correlation with other elements, e.g., Cu, As and Sb, within the ore matrix and process streams. The traditional QEM-SCAN analytical approach can prove problematic for some mineralogies due to difficulties in recognising degrees of crystallinity, polymorphs, complex solid solution series, high value trace element mineralogy, very fine grained materials; and the requirement for a comprehensive data base. Moreover, there is difficulty ‘seeing’ either surface films or surface contaminants which can both lead to poor flotation performance. There is therefore clearly a need to develop confirmatory and complementary approaches when these uncertainties arise. Synchrotron X-ray microprobe analysis provides a powerful tool for the mineralogical characterisation of finely segregated heterogeneous Ag-containing materials. These measurements enable comprehensive characterisation of the Ag-bearing components using synchrotron microprobe X-ray fluorescence mapping (µ-XFM), X-ray diffraction (µ-XRD) and X-ray absorption spectroscopy (µ-XAS). Further analytical strength is provided by principal component analysis of laboratory ToF-SIMS data which enables the statistical identification of correlated surface species enabling examination of surface chemical characteristics responsible for mis-reporting of Ag containing components within flotation streams. We describe the application of these techniques to a selected Ag-containing feed and tail and demonstrate how these compliment and extend traditional analytical methodologies."

Jan 1, 2014

By József Faitli, Barnabás Csoke, Károly Solymár, Zoltán Hatvani, Dimitri Papanastassiou

"Grinding has a significant economic impact on ore dressing/processing, therefore the sizing of mills has an outstanding role.In most cases, the sizing of dry or wet mills for ore processing is primarily based on the determination of the Bond grindability index, using the Bond-Kjos-Rowland relations. In several cases, grinding takes place under conditions different from these and the grinding conditions have a great influence on the post-grinding process. This is particularly true for the grinding of bauxites where grinding takes place in alkali, often in higher temperature (up to 100 ºC) in alkali Liquor. So it is necessary to develop a testing method providing a reliable grindability index even under these special circumstances (grinding in alkalis medium at different temperatures) and allowing a more precise mill sizing. The new heated mill is suitable to determine the grindability index under temperature-controlled circumstances, in liquids with different temperatures (water, alkali). This paper presents in detail the equipment, the conditions (parameters) of the testing process for wet and alkaline grinding, the measuring results and the conclusions."

Jan 1, 2003

By C. V. G. K. Murty

Sillimanite, chemically named Aluminum silicate, 3Al2O3SiO2 is one of the three forms of alumino silicate polymorphs and commonly encountered in aluminous metamorphic, plutonic, and volcanic rocks and their weathering products. Most of the sillimanite deposits are granular and are of high grade available in coastal areas as associated mineral along with Titanium bearing minerals namely ilmenite, rutile etc. Sillimanite is one of the widely accepted raw materials for the manufacture of high alumina refractories (55-60 % alumina) or bricks. Sillimanite based refractory bricks are used for the lining of Blast furnaces, Arc furnaces, Soaking pits, Reheating furnaces of iron and steel, rotary kilns for cement manufacturing and general kilns for lime production. Considering the vast potential of unexploited sillimanite reserves in India, M/s Trimex Sands Pvt. Ltd., (TSPL)has set up a Mineral Sand Processing plant in 2010 at Andhra Pradesh with a capacity to produce about 50,000 tons of sillimanite per annum besides the production of various heavy minerals such as ilmenite, rutile, zircon and garnet. Traditionally in India, sillimanite is upgraded by froth flotation technique using Oleic acid as a collector cum frother, sodium silicate as depressant and soda ash as pH regulator. At TSPL, Conventional mechanical float cells are installed to float sillimanite. In addition to the usual problems associated with conventional cells, poor flow ability of the sillimanite concentrate is experienced in dry circuit due to the presence of sodium oleate. Fine garnet in the sillimanite concentrate contributes to high iron content in the final product, making sillimanite separation a nightmare for operators (lower recoveries coupled with inferior grades). Various efforts were made to improve the performance of the circuit such as introduction of additional frother like MIBC, optimizing the operating parameters such as pulp density, collector dosage, depressant dosage, air flow rate, pH etc., use of collector aids, stage wise addition of reagents etc. The challenges faced to produce a sillimanite product with stringent quality norms and the efforts made to improve the grade and recovery are described in this paper. Keywords: sillimanite, froth flotation, conventional mechanical cell

Sep 1, 2012

By A. Bahrami

Andalusite, silimanite and kyanite are polymorphs of aluminosilicate known as kyanite group. Minerals of this group are used in refractory. Sarband andalusite deposit is located in Markazi province in Iran. Mineralogical studies showed that the main minerals of this sample are andalusite (5%~10 %), mica, quartz and feldspar. Processing of the samples was carried out using two sizes, i.e. +500 µm and -500 µm. In the processing of +500 µm scrabble test was carried out on -4750 +500 µm and -2380 +500 µm. For -500+300 µm shaking table and magnetic separation were applied. For -300 µm fraction, flotation was carried out. The results of this tests showed that the processing of Shazand andalusite was not possible, because silica and iron impurities were diffused inside the andalusite mineral grains.

Jan 1, 2014

By I. A. Makalin, V. N. Yakovlev, S. V. Imangulov, I. V. Zyryanov

"The presented studies aimed at solving the problem of recovery of low-luminescent diamonds, which are not recovered using X-ray luminescence method of processing of diamond-bearing ore. The purpose of the studies is the determination of possibility and feasibility of recovery of such crystals using dual-energy X-ray transmission separation technology. In preparation for studies methods were developed for testing technical and process parameters of XRT-400 Aliud GmbH (Germany) sorter, manufactured according to design specifications of Yakutniproalmaz Institute, and XRT/D TOMRA Sorting Solutions GmbH (Germany) sorter, designed for processing of -50+5 mm ore, as well as RGS-1M, RGS-2 X-ray sorters, developed by JSC NPP Bourevestnik (St. Petersburg) in cooperation with Yakutniproalmaz Institute, for material size of -6+3 mm. In 2018, in-process tests of RGS-OD-3 X-ray sorter prototype on material size of -3+1 mm are scheduled. Studies to determine the content of low-luminescent diamonds and feasibility of their recovery using XRT-400 and XRT/D sorters at the Processing Plant #3 of Mirny Mining and Processing Division (MPD) were carried out. The results of the studies confirmed presence of such diamonds and possibility of their recovery using the dual-energy X-ray transmission method. In-process tests of RGS-2 X-ray graphic sorter were carried out at the Processing Plant #16 of Nyurba MPD. According to the results of sampling of RGS-2 sorter separation products, the recovery of -6+3 mm sized diamonds from tailings of X-ray luminescence sorters was achieved at the level of 96%, while the diamonds recovery was 98.5% in value terms, the concentrate yield was 0.1%. In-process tests of RGS-1M sorters at final recovery of the grease separation concentrate at the Processing Plant #3 of Mirny Division were carried out. Recovery of low-luminescent -6+2 mm sized diamonds by RGS-1M sorter amounted to 92.4% for single operation, and with the double control operation reached 99%. As a result, -6+2 mm sized base product recovery increased by 0.2%."

Jan 1, 2018

By H. R. Manouchehri

The importance of the grinding environment and its effect on sulphide minerals flotation behavior has been known for many years. The grinding environment may play a role in controlling fine and coarse particle flotation along with dissociation of different chemical species in grinding environment. Dissociation of different chemical species and ions within the process water may result from changing the grinding environment. The mining and mineral processing industry undertakes activities that may impact on water resources. These include use and storage of chemical storm-water management, process water management, mine dewatering and management of tailings. In mineral flotation understanding and controlling water quality is paramount important not only because of its effect on flotation but also with respect to control the quality of the water which is released to the environment. Releasing of different anionic and/or cationic chemical species in the process water results from the interactions among different mineral within the ore, process water, and the milling environment. In fact grinding mill acts as an electrochemical reactor which affects the flotation performances of different value minerals as well as the quality of the tailing products. An increasing in antimony content in process/discharge water at Boliden?s Tara processing plant in Ireland to above limitation level was reported in April 2010 which needed to be controlled. An increase up to 6 times of the permitted level was reported which needed an immediate action to control due to environmental considerations. Therefore attempts were made to detect why this higher amount of Sb is released and how to control and minimize its release to the process/reclaim water. This paper discusses how/why Sb content in process/reclaim water was increased by changing the mill electrochemistry and the strategies were taken into considerations to control it. Different strategies, including electrochemical controlling of the milling section, Fenton process, using Bauxsol in treating the process water, etc., have been considered and tested which are described herein. All strategies taken into consideration for solving the problem were successful which indicated good understanding of the issue and good decision making. Furthermore, for each solution the capital and operational costs were roughly estimated. Accordingly, the Sb content in process/discharge water was controlled to a value lower than allowed limitation, i.e., 1 ppm. Keywords: antimony, water contamination, mill electrochemistry, ag milling, grinding media, eh-ph, sulfide minerals, fenton process, bauxsol, lime addition

Sep 1, 2012

By W. X. Yin

Electrowinning of lead from aqueous solution of PbCl2 and electrowinning of manganese dioxide from aqueous solution of MnCl2 are two research focuses in hydrometallurgy. This paper investigated a new process of simultaneous electrowinning of lead and manganese dioxide in chloride medium. The simultaneous electrowinning process in chloride solution not only can prevent chloride from liberating at anodes but also obtain two electrolysis products and decrease electric energy consumption. Diaphragm cell is used in the simultaneous electrowinning process to form separate anode and cathode compartment. The effects of temperature, HCl concentration in anolyte, NaCl concentration in catholyte and electrolysis time on current efficiency and cell voltage are studied. The results indicate that current efficiency of anode and cathode for 5 hours is 99% and 96% respectively, average cell voltage is 1. 701V, the weight ratio of lead and manganese dioxide produced at electrodes is 2. 39:1 under the optimum conditions. As anode products, manganese dioxide is ??MnO2, content of which in the products is more than 92%.

Jan 1, 2014

By G. Sedelnikova

This paper is aimed to elucidate the problem of copper losses in pyrometallurgical slag. Currently, flotation is used to recover copper from the slag and return the metal into the pyrometallurgical process, but the percentage of recovery frequently remains unacceptable. The process of copper leaching from the slag flotation tailings using biologically regenerated ferric sulfate is considered here as an approach to the issue. A sample of the slag flotation tailings containing 0.67% Cu and 4.99% Zn was supplied by the Urals Mining and Metallurgical Company (UGMK, Russia). The Cu and Zn speciation analysis of the sample demonstrated that Cu occurred as 58.1% oxide, 15.4% native Cu, and 18.1% secondary sulfides whereas chalcopyrite proportion was as low as 8.4%. Prevailing Zn species were refractory (58.9% Zn ferrite), and zinc oxide and silicate species made just 37.2% of the total metal content. The silicate generated silica gel that strongly hampered filtration. As demonstrated, Cu recovery is a possibility, which is apparently not the case with Zn. In this work, the stirred tank bioreactor acid leaching employing bacterial Fe3+ sulfate solutions was studied, with ferric sulfate being a product of Fe2+ biological oxidation and not the chemical reactant adding of Fe3+ sulfate. Acidithiobacillus, Sulfobacillus, and Leptospirillum bacilli were employed in Fe2+ biooxidation. Temperature, pH, Eh, S:L ratio, leaching time, and Fe3+ concentration in the source leachate as the process controls were considered. As demonstrated, the process employing biologically regenerated ferric sulfate proved to be more efficient than conventional chemical leaching. Under the optimum conditions, the proportion of Cu extracted into leachate during 2 hours was 79.1%, and that of Zn 27.2%. Precipitation of high-grade Cu sulfide served to extract the metals from the leachate, and Cu extraction was 99.7%. All in all, 23.2% Cu, 0.03% Zn, and 0.02% Fe was returned into the pyrometallurgical process. Keywords: slag flotation tailings, copper leaching

Sep 1, 2012

By Gu Guohua

The alteration of surface properties of chalcopyrite after biological conditioning with Leptospirillum ferriphilum was studied by adsorption, zeta-potential, contact angle and bioleaching tests. The strains of L. ferriphilum cultured using different energy sources (either soluble ferrous ion or chalcopyrite) were used. The adhesion of bacteria to the chalcopyrite surface was a fast process. Additionally, the adsorption of substrate-grown bacteria was greater and faster than that of liquid-grown ones. The isoelectric point (IEP) of chalcopyrite moved toward that of pure L. ferriphilum after conditioning with bacteria. The chalcopyrite contact angle curves motioned diversely in the 9K culture with and without chalcopyrite powders. The results of X-ray diffraction patterns (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis indicated that in the bioleaching process by L. ferriphilum, the surface of chalcopyrite was covered with sulfur and jarosite. Furthermore, iron phase dissolved preferentially from chalcopyrite surface during bioleaching from EDS detection. The copper extraction was low resulting from the formation of a passivation layer. The major component of the passivation layer that blocked continuous copper extraction was sulfur, not jarosite.

Sep 1, 2012

By Y. Lin

It is difficult to remove arsenic and bismuth from antimony in the process of crude electro refining. The electro refining of antimony has been studied using ammonium fluoride-antimony sulphate electrolyte system. The Influence of temperature, current density and additives on arsenic and bismuth removal from crude antimony has been investigated in this paper. Optimum process parameters, namely, temperature of 25?, current density of 400A/m2, distance between anode and cathode of 50mm, electrolytic period of 24 hours, oxalic acid dosage of 10g/L and complexon III dosage of 0.2 g/L have been ascertained.

Jan 1, 2014

By Irena Grigorova, Tashka Ignatova, Ivan Nishkov, Andrian Valchev

"Feldspars used by ceramic and glass industries as fluxing agents are mainly obtained from high quality feldspar deposits. The demand for feldspar as raw material for industrial applications especially in ceramic manufactures is continuously increasing. However, due to the depletion of those deposits, the research activities related to the recovery of feldspar from the lower grade feldspar deposits and feldspar bearing rocks such as pegmatite, granite, arkosic sandstone and syenite have been intensified in the last two decade. In Bulgaria, the main deposit of arkosic sandstone is located in the area of Shumen town, NE Bulgaria. In Srednya deposit arkosic sandstones are found in Upper Cretaceous sediments (Santonian). In this formation, there are two major industrial minerals - feldspar and quartz. They may be of economic value and possibly suitable for commercial uses. The main purpose of the present study was to investigate the beneficiation and upgrading processes of Srednya deposit arkosic sandstones. In a laboratory scale it was studied the possibility to obtain the feldspar concentrate and quartz sand from arkosic sandstones. Particle size distribution, chemical and mineralogical compositions of quartz-feldspar sands were determined. The bench-scale tests using the KOALIN AD laboratory experimental facilities were conducted. Many processing techniques were tested: disintegration, washing, sizing, carbonate flotation and feldspar flotation. The experimental results show that there are possibilities to obtain the silica sand with low content of Fe2O3 - below 0.02 % and potassium feldspar with content of K2O > 14 %. A new technology for recovery of feldspar and silica sand from arkosic sandstone was developed."

Jan 1, 2014

By B. W. Zhao

Quantitative analysis of minerals composing in ore is primary in process mineralogy, a veracious quantification and analysis is very crucial to optimize or design a beneficiation process, especially for a low grade and complicated ore. This paper will discuss a SEM-EDS based quantitative analysis developed in JKtech Australia through an example from Jinchuan lean ore. For a low grade, com-plex intergrowths and texture lean ore, chemical phase analysis of value minerals and identification by optical microscope are very essential, unite the SEM-EDS based quantitative analysis, we can understand exactly the lean ore, explain and quantify the process performance.

Jan 1, 2014

By Y. F. Guo

Laboratory scale experiments were conducted to produce titanium-rich material from Panzhihua ilmenite. The results showed preoxidation with sodium salt additive especially for Na2B4O7 signif- icantly advance the reduction of iron in Panzhihua ilmenite. Acceleration mechanism of preoxidation with Na2B4O7 has been studied here. The maximum metallization of iron 92% can be obtained under conditions of preoxidation at 850? for 30 min and subsequent reduction at 1100? for 150 min. The rusting separation technique to reduced ilmenite has been further studied, obtaining titanium-rich product with TiO2 over 82% and the recovery of TiO2 above 97%.

Jan 1, 2014

By K. Price, G. Wang, L. R. Moore, Y. R. Xiong, J. Gu

"Sand is a naturally occurring granular material that is a result of the physical or chemical breakdown of rocks. Raw/natural sand contains various minerals, and it is this combination of minerals that brings the value to the construction aggregate industry. However, it is the quartz component of sand that is valued in its application as industrial silica in glass, high purity quartz, foundry sand, and oil and gas fracturing. Depending on the industry, the grade requirements can be the concentration of SiO2, particle size or shape, as well as contaminants such as the heavy refractory minerals, clays, fines, and alkali metals. With the ever declining mineral feed grade, processors continue to face challenges making the industry specific concentrate grade. As such, it becomes more important to tailor make the processing reagents to fit the mineral, processing conditions, and desired quality specification. This paper focuses on the application of novel collectors towards the beneficiation of sand for each of the major industrial silica applications. INTRODUCTIONQuartz is a mineral composed of a framework of silicon and oxygen atoms. It is the second most abundant mineral in the Earth’s continental crust. There are many species of quartz, which are defined by the particle size, shape, and color. Silica sand is one of those species, which is the byproduct of the physical or chemical breakdown of quartz containing rocks or crystals. Geologist define silica sand as a silica mineral with a particle size between 0.05 and 2 mm in diameter (Zdunczyk, 2001). Silica sand has significant value to society in recreation (beach sand and toy boxes), construction aggregate (concretes and asphalt), industry (iron & steel casting, fracturing proppants, and glass), as well as specialty products such as semiconductors or silicon wafers used in electronics.The aggregate business is the dominant consumer of silica sand products. Conversely, glass making, foundries (casting material), abrasives, and fracturing proppants are the dominant applications for industrial silica sand. Not much beneficiation is required for sand products going into the construction industry, other than sizing and scrubbing to remove clay. However, the industrial silica sand applications are dependent on particle size, shape, and degree of contaminants, which sets the market value (table 1). Therefore, as the more specialty products are produced, more sophisticated techniques and chemistry need to be applied to ensure the appropriate quality is met."

Jan 1, 2018

By C. Y. Jia

Adsorption of Thiooxidans ferrooxidans and Mycobacterium Phlei on the surface of pyrite and galena was studied. From the experimental results, it was observed that Mycobacterium Phlei adsorbed preferentially on pyrite than on galena at neutral and alkaline pH values, while Thiooxidans ferrooxidans is not at all pH range, and the scanning electron microscopy photograph also indicated that. FTIR and XPS of two strains of bacteria indicated that there are much functional groups on surface of them, such as O?H, N?H, C-O, C?N, C?O etc, but S-O group occurred on Thioox-idans ferrooxidans cell surface and the P-O group appeared on Mycobacterium Phlei cell surface, and the content of C?O?H and C?O?C groups on Mycobacterium Phlei cell surface is higher than that on Thiooxidans ferrooxidans cell surface, this also been known from UVS investigation. The affinity of these groups to metal ions on sulfide minerals is able to explain the selective adsorption.

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