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By Naoki Hiroyoshi, Hajime Miki, Tsuyoshi Hirajima, Masami Tsunekawa

Acidic solutions for chalcopyrite leaching contain cupric, ferrous and ferric ions, and the oxidizing power of the solutions is indicated by a redox potential, determined by the concentration ratio of ferric to ferrous ions. This paper reviews our previous studies on the redox potential dependence of chalcopyrite leaching in sulfuric acid solutions. Leaching and anodic-polarization experiments showed that coexistence of cupric and ferrous ions activate anodic dissolution of chalcopyrite, causing faster copper extraction at the potentials below a certain value (critical potential). The analysis of the AC impedance spectra for chalcopyrite electrode indicated that a high-resistance passive layer grows on the chalcopyrite surface without cupric and/or ferrous ions, and that coexistence of these ions causes a formation of another product layer and inhibits the passive layer growth at low potentials. These results are explained by a reaction model assuming the formation of intermediate Cu2S due to chalcopyrite reduction and the subsequent oxidation of the Cu2S. The critical potential corresponds to the redox potential of the Cu2S formation and the predicted values matched with the experimental results. Catalytic effect of silver ions on chalcopyrite leaching was also discussed based on experimental results and the above model.

Jan 1, 2003

By O. A. Punishko, G. G. Mineev, Zabaikalsky Ore-Dressing Plant, M. V. Malova, O. V. Belousova, S. A. Bogidaev

"In order to intensify benefication processes (flotation and magnetic separation) for rebellious tantalitecolumbite ores electrochemical machining of pulp (ECM) is suggested instead of costly mechanic-chemical activation and magnetizing roasting. Any change in the surface mineral-semiconductor potential under the action of electrochemical treatment results in the change in the isoelectrical state of the surface and the adsorption property of the mineral with respect to ionogenic reagents-collectors. In this case conditions are created for regulating the ion composition, reduction-oxidation potential and pH of the liquid phase of the pulp without any extra introduction of expensive and often ecologically harmful chemical substances.Ores containing tantalum and niobium are characterized by complex chemical composition, determining their physical properties (conductivity, dielectric penetration, magnetization value, etc.) and their electric susceptibility.The authors investigations show that the pulp electrochemical treatment leads to the increasing magnetic susceptibility of the paramagnetic minerals. The main chemical elements forming the columbite-tantalite minerals except tantalum and niobium are iron and manganese. They determine the rare-metal minerals paramagnets properties. The electrochemical treatment changes the relation of the oxidized and reduced forms of these elements having. The method of cathode pulp treatment before flotation is successfully tested industrially.In the field of noble metals metallurgy new technological proposals are reduced to the following. As is know, the production of noble metals from unusual raw materials demands the elaboration of principally new technologies new technologies in so far as the methods for gold and silver extraction from ores are as a rule low elective and at the existing level of engineering are economically not expedient.The analysis of the main trends in the field of non-standard raw material treatment shows that the perspective ones are the geo- and biotechnological processes (underground leaching and leaching in heaps - UL and HL and microbiological methods of metal extraction)."

Jan 1, 2003

By Seungwoo Park, Gaurav Soni, Roe-Hoan Yoon, Hyunsun Do, Kaiwu Huang

In a flotation froth (and foam), air bubbles become larger due to coalescence, causing bubble size to increase, bubble surface area to decrease, and hence casing less hydrophobic particles to drop off to the pulp phase below. Thus, bubble coarsening provides an important mechanism by which product grades are increased. On the other hand, excessive bubble coarsening results in low recoveries. In the present work, a model describing the process of bubbles becoming coarser in a foam as they rise to the top by deriving a mathematical relation between the Plateau border area, which controls film drainage rate, and the lamella film thickness, which controls bubble-coalescence rate. The model has been derived by assuming that liquid drainage rate increases due to slip at the air/water interface, and that the critical rupture thickness is determined by the capillary waves created by thermal motion. The model developed in the present work can predict the bubble size ratio between the top and bottom of a foam as functions of aeration rate, foam height, and surface tension (frother dosage). The model predictions are in good agreement with the changes in bubble sizes measured using a high-speed camera.

Jan 1, 2014

By Xingshi Yang, Ghislain Bournival, Seher Ata

"Particle-laden interfaces are a fundamental research topic in froth flotation since the process involves particle-coated bubbles in both the pulp and the froth phase. In most experimental studies the characteristics of the particle layer in multi-bubble systems are poorly defined. An experimental setup has been developed based on a Langmuir-Blodgett (L-B) trough. The modified trough allowed introducing an air bubble beneath the particle monolayer formed at the air-water interface which made the study of the interaction between the bubble and the monolayer under various pH values possible. The monolayer characteristics of the particles were also studied and compared in terms of surface pressure (?-A) isotherms and packing factor. On compression, the particles formed branched structure at high pH whereas a uniform monolayer was formed at lower pH. Observations related to the behavior of particles during compression and expansion cycles, and the coalescence of a bare bubble with the flat particle laden interface were provided and the implication of the results for flotation process was discussed.INTRODUCTIONFroth flotation is known for its versatility and ability to concentrate low-grade, complex ores. It is considered a physico-chemical process in which particles attach to air bubbles, depending on their hydrophobicity as well as other factors, and are carried to the surface to form a froth layer. Reagents are used to stabilize bubbles and the froth layer (Pugh, 1996). However, particles, which are carried by the bubbles or entrained, significantly contribute to the stability of the froth phase (Ata et al., 2003; Zanin et al., 2009; Bournival et al., 2015a). Their relevance in mineral processing has led to a number of fundamental studies on the effect of particles and their properties on the process of froth flotation.Flotation systems are particularly difficult to characterize due to the broad range of properties of particles (e.g. size, liberation, hydrophobicity, etc.) and inconsistent operational conditions (e.g. changes in water quality, reagent addition, etc.). Several studies have made the use of well characterized particles in laboratory conditions. Such studies allowed the finding of an optimal contact angle for the stabilization of the froth phase (Johansson and Pugh, 1992; Ata et al., 2002). Froths have a large number of bubbles so that individual interactions are not observed. The study of two bubbles allows to determine the stability of the bubbles, with particles, and to some extend the stability of the bubble-particle aggregate (Gourram-Badri et al., 1997; Bournival et al., 2015b). The removing of particles between two bubbles may also be studied from a Scheludko cell (Johansson and Pugh, 1992) or by observing a bubble with a flat interface (Sethumadhavan et al., 2002). However, these systems provide limited information on the arrangement of the particles."

Jan 1, 2018

By Francisco Vicuña, Miguel Becerra, Nelson Iglesias

"The following article presents the development of a dynamic tool for the estimation of Jb/Jc rate (ball filling level / total load filling level) of a SAG mil operating in a single stage mode. Using the methodology detailed in this article, it is now possible to have a dynamic estimation tool in the operation, which enables strategic decision making and achieving a continuous development in process optimization. The estimating of the load filling level (Jc) was conducted using a power model, which in this case corresponds to the C-Model developed by (Morrell, 1993) that was calibrated by measuring the load filling levels (Jc) and balls (Jb) using the FARO laser scanning technology by means of Grind-Out and Crash-Stop procedures during the year 2013 and 2014. Finally, to estimate the dynamic filling level of full charge, Jc, three independent models were developed that allowed to feed the adjusted power model: •,SAG mill discharge grate slot wear model •,SAG mill internal volume wear model •,Ball filling level estimation model."

Jan 1, 2014

By Ghislain Bournival, Cagri Emer, Seher Ata

"It is well known among flotation practitioners that the contact angle can be correlated with the amount of material recovered from feed by flotation. The contact angle of solids can easily be modified by the addition of a collector. However, some collectors also have frothing properties thus altering the solid and bubble surface properties simultaneously. To avoid this problem, a technique has previously been used in which silanol groups are attached to the surfaces of the particles, but this method has its own problems. In this work, silica particles with various surface hydrophobicities were prepared using an esterification process. By using alcohols with different hydrocarbon chain lengths, from 4 to 12 carbon atoms, surfaces with a wide range of contact angles could be prepared. The technique was used in the modification of silica particles that were tested in a fluidized bed flotation column, and a laboratory mechanical flotation cell. In parallel experiments, dodecylamine (DDA) was used as a collector. It was found that irrespective of the type of flotation machine and surface preparation method, there was a close correspondence between flotation recovery and the contact angle of the particles. The silanation process has known drawbacks relating to the presence of moisture during the reaction, and the stability of the silane coating after it is been prepared. Esterification does not suffer from these disadvantages. This work has shown that the esterification technique is a robust alternative method for preparing hydrophobic quartz surfaces."

Jan 1, 2014

By Erico Tabosa, Kym Runge, Peter Holtham

"The distribution of turbulence in an industrial scale mechanical flotation cell and its effect on flotation kinetics was studied using a fully instrumented 3m³ cell. The cell was operated at a copper concentrator in Australia with different combinations of airflow rates, impeller speeds and sizes and cell aspect ratio providing a wide range of hydrodynamic conditions. An analysis of the overall flotation cell performance showed that the overall copper recoveries were very similar for the conditions tested. However, by decoupling pulp effects from froth effects it was possible to evaluate whether the changes made affected the pulp zone and/or froth zone responses. The analysis showed that the overall recovery has the potential to be up to 7% higher, if not limited by froth recovery. The cell hydrodynamics were characterised by the overall energy dissipation rate and, to understand the distribution of turbulence within the cell, localised measurements were made using a piezoelectric vibration sensor. By comparing the metallurgical performance of the cell with the different hydrodynamic conditions it was found that the collection zone flotation rate constant was not directly related to overall energy dissipation, as is commonly observed at laboratory scale, where energy is usually only changed by varying impeller speed. In this study, energy dissipation rate was varied using not only impeller speed, but also the size of the impeller and the cell aspect ratio. In these circumstances, the best correlation was found to be between the collection zone flotation rate constant and the distribution of turbulence, i.e. the size of the turbulent zone."

Jan 1, 2014

By Martin Rudolph

"Flotation is without a doubt one of the major processes for the separation of fine minerals and it has been applied for more than a century. A key task of a successful flotation separation is to find the proper chemical treatment to selectively hydrophobize and thus float a certain mineral phase using molecules or ions referred to as collectors, depressants, regulators and frothers. Commonly floatability is determined by microflotation tests using the Hallimond tube with pure mineral phases. This method however requires the pure mineral phase which is very often not even taken from the same deposit which is going to be processed. In this paper we present a new approach to in-situ determine and even map the floatability of finely disseminated mineral phases within cross-sections of an ore. It is based on measuring hydrophobic effects using colloidal probe atomic force microscopy with a hydrophobic polystyrene probe based on force spectroscopy with a lateral resolution of only a few nanometers. Coupled confocal Raman spectroscopy on the same locality enables the identification of the mineral phase. We present the working principles of the method and show which signals in the force spectra characteristic for hydrophobic interactions can be used to define floatability and which can then be mapped as single quantities, e.g. jump-into-contact events due to nanobubble occurrence or parameters of the long range interaction curves most probably due to capillary effects. A finely grained silicate ore containing the valuable rare earth mineral eudialyte from southern Sweden as well as pure samples of magnetite are presented as substrates to demonstrate the capability of this new approach. This method will not only help to find the proper flotation chemistry but it can furthermore help in researching and unravelling problems of floatability within similar mineral phases."

Jan 1, 2014

By In-Kuk Bae, Kwang-suk You, Joobeom Seo, Kwanghyun Bea, Hyung-Seok Kim

Arsenic in base metal sulfide ores is highly penalized owing to high costs for its control in metallurgical processing. The arsenic element in the lead-zinc ore, which is target ore in this study, has been shown to be in the form of arsenopyrite. Experimental work in this study is about arsenic rejection flotation, using depressant suitable for the removal of arsenopyrite from the Pb concentrate. The arsenic rejection flotation also included the oxidation treatment of Pb concentrate with H2O2. In this study, the Pb concentrates containing 80.7% Pb and 0.25% as was obtained with the additions of aluminosulfate as arsenic depressant. And through IR measurement, it was also known that the addition of aluminosulfate during arsenic rejection flotation formed calcium aluminosulfate hydrates on the surface of arsenopyrite particle, resulting in rendering arsenopyrite hydrophilic.

Jan 1, 2014

By H. Koca, D. O. Aksoy, S. Koca

"In this work, modelling of galena flotation from a disseminated Pb-Zn ore containing 0,83 % Pb was investigated. In the flotation experiments, collector type and amount, frother type and amount, particle size, pH and flotation time were kept constant while solid ratio and depressant dosage were varied. The varied parameters are described with a mathematical model by using statistical design method. Central Composite Design method which is one of the principle response surface methodologies was used in statistical design and analysis of experimental results and process modelling. Two quadratic mathematical models were developed for Pb grade and Pb recovery. Analysis of variance showed that models obtained for Pb grade and Pb recovery were found to be statistically significant in 95 % confidence level. Predicted vs actual values of Pb grade and Pb recovery were also given in graphically. It was found that predicted values represent approximately 96 % and 94 % of actual Pb grade and Pb recovery, respectively. The high values of R-square (R2) indicate that the models developed for two response variables are powerful. INTRODUCTION Lead and zinc metals are widely used in electrical, mechanical, military, metallurgical, chemical, light and medical industries. Sulfide ores are the main resources for lead and zinc minerals (Luo et al., 2016). Froth flotation is the main beneficiation method to achieve lead and zinc sulfide minerals separation. There are two basic approaches to obtain lead and zinc separation by flotation. First, flotation of lead sulphide is carried out and zinc sulphide and gangue minerals are depressed by various depressants and second, the bulk flotation of lead and zinc sulphide is carried out to obtain a concentrate of lead and zinc, followed by the lead and zinc separation. (Yuan et al., 2012). Apart from concentration of lead and zinc by flotation, there are a few literature that reports concentrations of lead and zinc by gravity and hydrometallurgical methods with remarkable success (Goktepe, 2005; Yanbo et al., 2016)."

Jan 1, 2018

By M. Mezzetti, E. Anders, O. Popov, P. Hoske, H. Lieberwirth, M. Voigt

"The material breakage induced by high energy electric discharges is known in general as electric impulse technology. This technology can be used for processing solid materials, such as rocks and ores. The electric impulse technology has been around for about 60 years, originally developed and intensively investigated by Russian researchers. However, the application fields have been limited to research and laboratory scale projects. Currently, there are new attempts to transfer this technology into practical industrial applications. Practical examples include drilling of deep geothermal wells with an electric impulse driven drill-head. Traditional comminution implies high energy consumption, hence, high costs. The Electric Impulse Technology is interesting for comminution of mineral and complex ores since it could allow improved recovery and energy reduction, thus resulting in significant savings. Another advantage is the dust free processing, which contributes to make minerals processing environmentally friendly. The use of electrical comminution for processing complex ores is investigated within the ELIZE research project funded by the BMBF (project No. 033R161 A) and industrial partners. The main objective is the development of an industrial scale electrical comminution machine. The first development stages include the investigation and characterization of the electric impulse induced weakening on rocks and ores. The characterization results of the preliminary trials at the microstructural scale on granite, skarn and greisen will be presented and discussed in this article. INTRODUCTION The pioneer work in the area of electric impulse technology was conducted by Russian researchers about 60 years ago [1]. While there have been some successful attempts to transfer this technology into practical applications, such as rock processing [2], laboratory processing of mineral ores [3–5], recycling [5] and geothermal drilling [6–9], the jump into practical industrial large scale application has not been accomplished yet. The Institute of Mineral Processing Machines of the TU Bergakademie Freiberg currently leads a project which can be seen as the next logical step for the technology transfer to industrial applications, namely, the development of continuously operating complex ore processing machines based on the electric impulse technology."

Jan 1, 2018

By Y. M. Zhu

Lead in environment often causes a serious health hazard. The removal of Pb2+ from aqueous phase is a beneficial project. In this paper, deposited Saccharomyces cerevisiae (S.c.) was chosen as adsorbent, Pb2+ ions as adsorbate, and the process of biosorption was studied. The dynamics of the adsorption was investigated. The adsorption mechanism of Pb2+ by S.c. cells was also investigated by detecting microstructure, zeta potential under different pH value, FT-IR spectra of the S.c. particles before and after biosorption. It was shown that the biosorption of Pb2+ by deposited S. c. is a rapid process, and the adsorbing equilibrium is reached within 10 minutes. The Zero point of zeta potential of S.c. cells is pH=3.3. When 2.0<pH<3.3, there exists biosorption (biosorption rate 76%~88%), which means static bio-sorption been not the only kind of biosorption. FT-IR spectrum analysis showed that groups on bacteria surface were mainly characteristic groups of protein and amylase; oxo-groups and nitric-groups on S.c. cell surface could chelate with heavy metal ions. Chemical adsorption might exist in the process.

Jan 1, 2014

By G. K. Nimal Subasinghe

The establishment of grind size that optimally liberates the valuable mineral for efficient down-stream processing is of great importance for most mineral processing operations. Reasonably accurate comminution models as well as models of downstream separation processes may be found in the literature but their use in optimizing grind size is limited without an associated liberation model. In this work, an attempt has been made to address the above shortcoming by demonstrating how the effective parameters of the downstream flotation process may be predicted from the liberation characteristics based on the ore texture data for a disseminated nickel ore. In this regard, the liberation model based on linear intercept distributions of mineral and gangue proposed by King (1979) and its application to predict the flotation performance of an industrial plant demonstrated by Schaap (1979) may be considered useful contributions. However, while the model proposed by Schaap is simplistic enough, it is based on several assumptions due to the non-availability of intercept length measurements on the parent rock, in particular, on the extent of mineral exposure on the surface of comminuted particles. In this work, the linear mineral and gangue intercepts on polished specimens of a binary ore, comprising darker pentlandite as the valuable mineral and lighter barren host rock were measured using an image analyser. The resulting intercept distributions followed negative exponential distributions. Using the mean sizes of mineral and gangue intercepts, the proportion of liberated, compo-site and mineral occluded particles of a given size, the extent of mineral exposure on the surface of particles and their mean mineral contents were calculated using principles of renewal theory. The rock was then crushed and ground and different size fractions were floated. It has been shown that the parameters of observed recovery data based on 1st order kinetics such as the associated rate constant and ultimate recovery agrees well with those predicted from the quantities calculated above. This work has important practical implications since it can indicate variations in flotation performance arising from changes in mineralization within a large ore body.

Jan 1, 2014

By Yagmur Sirinyurt, Ayhan Ali Sirkeci, Gülay Bulut, Mustafa Özer, Tuncer Acar

"The basic requirement of glass industry for the silica sand is at least 99% SiO2 content. On the other hand, coloring impurities such as Fe and Ti, must be removed. Flotation is the most widely used method for the purification of silica sands from impurities. In this study experimental studies were carried out to reduce Fe content of Mersin (Turkey) district silica sands by flotation. Silica sand sample with a d80 particle size of 1.85 mm was reduced below 0.5 mm in size. Then the size fraction -0.5 +0.106 mm was subjected to flotation tests. In flotation tests, sulfonate-type R801-R825, fatty acid based DER NA 7 (Produced by a Turkish company) and HA110-HA150 a blend of various chemicals produced by Mersin Cam-Is Mining Company (producer of glass raw materials) were used as collectors. Flotation tests showed that sulfonate type R801-R825 collectors provided much better results in acidic medium (pH: 3). The optimum pH value for DER NA, HA150 and HA110 collectors was found to be 7. It was observed that the addition of collector at once caused an increase in the amount of floated product that resulted in a loss of silica to the tailings. In the case of multistage addition of the collector much better selectivity was achieved. As a result of flotation tests conducted under best conditions, a concentrate assaying 0.046% Fe was obtained with a weight percentage of 93.4 when DER NA 7 was used as a collector. In the case of R801-R825 a concentrate was produced with 0.058% Fe content with a yield of 98.4%. On the use of HA150-HA110 the concentrate was produced with 96% weight recovery and 0.052% Fe content."

Jan 1, 2014

By Áureo Del Vecchio, Lídia Dely Alves de Sousa, José Pereira

The potassium demand for agriculture purposes has increased in Brazil, which has great deficit of internal demands. Potassium-rich rocks have been used as fertilizers as technological alternatives for agriculture aimed to reduce the amount of chemicals and the sector dependence for such products. Vermiculite tailings from União Brasileira de Mineração - UBM, at Santa Luzia - PB, was studied aiming their application in agriculture by potassium release. The sample was analyzed by XRF and XRD; studies on release kinetic with particles smaller than 2 mm added of organic acids (citric and oxalic) at 10-2 mol/L concentration; samples were analyzed by XRD after kinetic assays. The work was conducted using a shaker incubator at 300-rpm agitation and time variation to better understand the potassium availability in the ground. Results show the presence of K2O at 3.46% concentration. Citric and oxalic acids increased the release speed to almost the same level with speed coefficients (k) of 2.61x10-2 h-1/2 and 2.55x10-2 h-1/2 respectively. In statistical terms for both acids, the linear equation represents more than 99.0% of the experimental assays. Stonemeal was applied to banana seedlings in experiment conducted in a greenhouse. The use of vermiculite tailings in banana seedlings promoted potassium absorption, which influenced its growth. The amount of potassium liberated from vermiculite tailings could be used as a long-term alternative to fertilizers in agriculture cultures.

Jan 1, 2014

By Hugo Barrientos

"The growing need to optimize the mining processes produces a need for users to have a simple, reliable, secure and cost-effective method to monitor the values of the variables measured in field. The solutions described in this paper, we will demonstrate how the implementation of Emerson Smart Wireless technology helps to optimize the leaching and electro winning processes. An effective monitoring of the variables involved in the operation of a heap leach, such as pressure, flow rate, pH, water level control and regulator valves can improve production and optimize the use of sulfuric acid, which results in a more effective management of resources and helps reducing input costs. Moreover, the constant monitoring of variables prevents the risk of landslides, reducing maintenance costs. In electro winning cells, the wireless solution measures variables such as pressure, flow rate, temperature and voltage provides a performance indicator for the entire operation, capable of detecting and predicting shorts, and monitoring the overall functioning of a cell or group of cells. As a result of the applications studied, users can monitor variables in real time, optimizing the use of resources, quickly detecting possible flaws in the process and reducing the risks in the operation. All these factors have a direct impact on company results."

Jan 1, 2014

By Fu Ping-Hao, Sergio Mauricio Vianna, Ewen Silvester, Emmy V. Manlapig

"Over the last 5 years, an ambitious project has been undertaken at the Julius Kruttschnitt Mineral Research Centre (JKMRC) aiming to isolate, study and, if possible, model the effect of particle size, liberation and collector adsorption density on the floatability of mineral particles. As part of this project, we have conducted highly controlled flotation test-work, combined with state-of-the-art solution and surface analytical techniques such as High Performance Liquid Chromatography (HPLC), Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) and detailed mineralogical analysis to fully characterize the flotation behavior of a natural ore.The flotation tests were undertaken using a high-grade lead-zinc ore from BHP-Billiton’s Cannington mine (Australia) in a specially designed continuously operated laboratory scale flotation rig. Solution and adsorbed collector concentrations were measured independently during the course of the flotation tests using HPLC based ex-situ techniques. Liberation studies were performed using the JKMRC Mineral Liberation Analyser (MLA) on selected size intervals of different streams to estimate the specific surface area of galena. These results were used to calculate the collector adsorption density (collector coverage) on galena particles, with the eventual aim of developing a mathematical model describing the relationship between pulp chemistry, feed mineralogy, and floatability of galena particles."

Jan 1, 2003

By C. Stollberg

The recovery of valuable materials from electronic waste is of growing importance for the re-source management not only in the industrialized nations. Being a significant step in an innovative automated process for recycling of metals and plastics from used electric and electronic equipment, the results of the work introduced below, prove the applicability of microbial leaching of metals from printed circuit boards (PCBs) at industrial scale. Within the first project step, which started in March 2005, experiments in shaking flasks with a mixed culture of chemolitotrophic bacteria (mainly Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans) were carried out to study the solubilization of non-ferrous metals present in the electronic waste. It was found that the best results were achieved by means of a two-stage process in which leaching of these metals was carried out by acidified ferric sulphate solutions generated as a result of the prior bacterial oxidation of ferrous ions to the ferric state. Special reactor systems for bacterial generation of such solutions and for the subsequent leaching of non-ferrous metals from the waste were developed, constructed and tested under laboratory and pilot scale conditions. The optimum technological parameters such as concentration of iron ions, pH-value, temperature and presence of nutrients were established for both reactor systems. Parameters such as particle size, pulp density and flow rate of the suspensions being leached were established for the leaching process carried out under continuous-flow conditions. The complex flow sheet reflects a highly efficient technology on the basis of metal recovery, environmental effect and economical acceptance. The process was successfully implemented into an industrial demonstration unit.

Jan 1, 2014

By Christian O’Keefe, Alex Van der Spek

"Evaluation of inequalities of the partial sums defining cumulative grade and recovery prove that cumulative grade has an upper bound not dependent on the bank number and cumulative recovery possesses an upper bound proportional to the bank number. This explains one observed characteristic of cumulative grade versus cumulative recovery curves. The existence of such maxima combined with the observed shape of cumulative grade-recovery curves leads us to postulate that these curves can be well described by rectangular hyperbolae. Rectangular hyperbolae are characterized by asymptotes at right angles to each other. It is proven that this property can be used to derive an equation for the cumulative mass flow of the concentrate in terms of the asymptotic values of cumulative grade and cumulative recovery. Fitting hyperbolae to experimental cumulative grade cumulative recovery plant data then results in estimates of the maximum grade, the maximum recovery and a constant which may be taken as a performance coefficient of a row. Normalization of the cumulative grade and the cumulative recovery by their respective maxima gives rise to a graphical representation that can be used to evaluate the operating performance of a row of floatation bank cells. The normalization procedure removes the bias that is introduced by inevitable variation in mass flow of the feed and variation in feed mineralogy or feed particle size distribution. Reduction of the normalized data collapses all cumulative grade-recovery data onto one and the same curve. This removes the differences caused by the variation in row performance. The reduced cumulative grade-recovery data scatters around a common hyperbola. This can be used to gauge the validity of the assumptions made. Normalized cumulative mass pull is determined from the fitted values of the maximum recovery and maximum grade. This may serve as an alternative performance indicator of the floatation row."

Jan 1, 2014

By Kazutoshi Haga, Atsushi Shibayama, Kosuke Nishioka, Yasushi Kihara, Altansukh Batnasan

The aim of this study was to investigate the feasibility studies of seawater in flotation of a 1.5 mass % of copper containing copper sulfide ore. Effects of seawater, various frothers, and different distilled water/seawater ratio on flotation of copper sulfide ore were studied. Surface properties of native copper ore and sea water soaked were examined by using FT-IR spectrometry. Chemical contents of the copper sulfide ore and after flotation were identified using XRD studies. XRD pattern showed that the main constituents of the copper sulfide ore are chalcopyrite (CuFeS2), bornite (Cu5FeS4). Flotation experiments were carried out using mechanical agitation flotation equipment with a mineral separation type flotation cell. Froth flotation experiment was conducted using calcium hydroxide was used as a pH adjuster, using methyl isobutyl carbinol (MIBC), dow froth 250 (DF 250) as frothers and potassium amyl xanthate (PAX) as collector for the copper recovery from the copper sulfide ore containing chalcopyrite and bornite. The results showed that the copper recovery by flotation was dependent on the flotation medium and frother. The main results showed that the copper recovery by flotation was dependent on the process water and frother. The copper recovery reached 97 % and 87 % in the distilled water flotation and seawater flotation with MIBC, respectively. For seawater flotation with DF 250, the Cu recovery achieved near 95 % and grade of Cu in the froth product after 5 min flotation was reached 29.8 mass %.

Jan 1, 2014