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By Bruno Miotto, Rômulo Faria, Juliano Tessinari

Water has become a scarce resource in quality. Companies in the ornamental stones sector use water intensively in their processes. Given the current situation, it is imperative to rationalize this feature that at first is related to the reduction of consumption, through no waste. Considering the importance of environmental preservation of this resource and also to comply with the legislation that governs the procedure for processing of ornamental stones, new alternatives should be available for the maintenance of current activities and promoting the development / growth of the sector on the principles of environmental sustainability and economic in future scenarios. The ornamental stones processing industries, especially for micro and small enterprises, require the implementation of a management program that optimizes the use of this feature, since the techniques individually processed operate with three basic processes dependent on water use: split blocks, polishing and finishing slabs. This technology requires a large volume of water resources and control measures involving operating recirculation water can minimize power consumption, making the company more profitable and sustainable. This is a survey of literature, associated with technical reports provided by partner companies and government agencies. This study aimed to the organization and provision of theoretical knowledge about the subject matter coupled with management practices, which may be reproduced or re-purposed in ornamental stones processing companies. It should be noted that the industry in question is lacking in technical expertise for the implementation of sustainable attitudes relevant to water reuse.

Jan 1, 2014

By G. K. Nimal Subasinghe

The performance of Knelson Concentrators (KC) used in gravity gold circuits often rely on manufacturers recommendations for selecting operating parameters such as, fluidising water flow rate and cycle time. These parameters are not only dependent on the machine parameters but also on the feed characteristics such as, size distribution of the gold and gangue particles and the composition of its constituent minerals. Particles entering a KC experience a centrifugal acceleration due to the high bowl rotational speeds. The required centripetal force to maintain a circular orbit is provided by the fluid drag force created by inwardly moving fluidising water and the Bagnold?s force arising from the particle/particle collisions. When the fluidising water flow rate is low particles move towards the outer rim of the bowl forming a packed bed within the grooves. On the other hand, if the fluidizing water flowrate is high the bed expands and some particles would move towards the centre of the bowl and gets carried to the tailings stream, thereby reducing the amount of material retained within the grooves of the bowl. Based on a force balance on a particle captured within the KC, a criterion which can be used to predict the amount of material recovered in the bowl has been derived and validated by experimental data. It has been shown that this criterion may be used to demarcate the transition of the bed from a packed-bed state to a fluidised state depending on the fluidizing water flowrate. By identifying the conditions for the optimal expansion of the bed comprising different constituent mineral particles, it is possible to estimate the optimal fluidising water flow rate that would maximise gold recovery while minimising gangue recovery. It was also observed that the accumulation of valuable mineral in the bowl takes place by the displacement of the gangue particles in the bed by the incoming heavy mineral particles. The kinetics of this segregation process was also studied using synthetic mineral mixtures. The experimental data suggests that this process follows first order kinetics and that the build up of heavy mineral reaches a maximum which could be used to identify the optimal cycle time. In this work, the suitability of the above model in optimizing the performance of a KC have been reviewed. Also the necessity and merits of testing an unaltered

Jan 1, 2014

By H. D. Mendoza, M. J. C. Zerna

This study aims to determine the stability of Philippine nickel laterite ore by investigating the behavior of fine minerals of silica (dave=1.514 µm), hematite (dave= 0 1.351 µm), and nickel oxide (dave=1.426 µm) and their mixed-components in dilute aqueous suspension as a function of pH and electrolyte concentration. The zeta- potentials of the minerals are measured and stabilities of different component systems in aqueous suspension are determined. Hamaker constants of the minerals in aqueous medium are derived by getting their respective critical coagulation concentrations (c.c.c.) at stable pH conditions and at various concentrations of KNO3. The iso-electric points (i.e.p) for silica, hematite, and nickel oxide particles are at pH 2, pH 7.5, and pH 8.5, respectively. The stability behaviors of component systems are as follows: a) Silica dispersion is stable at pH range 3-11and unstable at pH 2; b) Hematite dispersion is stable at pH 2-5 and pH 8-11, and unstable near pH 7; c) Nickel oxide dispersion is stable at pH range 10-11 and unstable at pH 3-9; d) Hematite-silica dispersion is stable at pH range 6-11 and unstable at pH range 3-5; e) Hematite-nickel oxide dispersion is slightly stable at pH range 3-4 and unstable at pH range 5-11; f) Silica-nickel oxide dispersion is stable at pH range 10-11 and unstable at pH range 3-9; and, g) Hematite-silica-nickel oxide dispersion is stable at pH range 10-11 and unstable at pH range 3-9. The stability of nickel laterite ore is similar to that of the three-component system in an aqueous environment. The stability tests are analyzed using the classical DLVO theory. The stability conditions in an aqueous environment are essential in developing the appropriate process flow for the separation/ recovery of nickel laterite mineral components and also in the treatment of nickel laterite -laden wastewaters.

Jan 1, 2018

By A. V. Golovanov, A. V. Mihailova

"NPO RIVS employs complex approach to engineering and design of the new facilities in close cooperation of Mining, Research, Hydrometallurgy, Design, Construction, Power Supply, Automation, Production and other departments. General Design Contractor (and then General Contractor) is directly involved in geological exploration, engineering surveys, floatability studies, feasibility study of process solutions and construction options. It delivers greenfield project and guarantee its efficient performance in future. Shiralgin is a small gold and copper deposit, gold average grade is 4.7 g/t. RIVS departments have studied ore floatability, developed process procedures for design and performed pilot testing. Construction of integrated plant including ore crushing and grinding, flotation and hydrometallurgy units with Dore gold production of 5 000 thousand tons ore per year (66.7 t/h) is recognized as economically viable. The technology used of separate dry stockpiling of flotation tailings and cyanidation tailings. Water circuit for concentration and hydrometallurgy is separated, too. Process design was performed based on BIM software like Autodesk Revit, Civil 3D, Rocscience slide using process procedures developed by RIVS Research units. Engineers provided modeling of primary crushing unit, coarse ore storage, main building (including grinding, flotation, thickening, filtration, loading, hydrometallurgy), tailings thickening unit, building for reagent storage and conditioning, tailings pond for dry stockpiling of flotation tailings and cyanidation tailings, sedimentation ponds, laboratories, infrastructure including Administration building and camp. Payback period is 3.5 years. 3D model of facility is currently stored at the State Agency of Geology and Mineral Resources affiliated to the Government of the Kyrgyz Republic.INTRODUCTION The Kyrgyz Republic has substantial potential of mineral resources including gold ores. Mining industry actively develops and involves international investors. Inventory includes 42 deposits (Figure 1) that have reserves of 616.4 t [1] of gold. The Kyrgyz Republic takes the third place in gold mining among CIS countries after Russia and Uzbekistan by producing up to 20 t annually."

Jan 1, 2018

By B. Csoke

To improve the efficiency of the crushing/screening plant of Bazalt-Középko Kobányák Ltd. (Hungary), the implementation of computer aided quality control is planned. In the current phase, the R & D work aims at the solution of high-priority tasks: 1) Developing the process models, validation of the models by means of industrial measurements. 2) Developing the algorithm for the process control of the crushing/sizing plant. 3) Developing the suitable computer program. To develop the mathematical models of crushing (breakage and probability functions) and to determine the model parameters, the experimental industrial trials were carried out on hydrocone crushers of types Svedala H 4800 EF and H 4800 F, changing the gap size and crushing relatively narrow grain size fractions. Additionally, the parameters of the separation function for the screens operating in the system were determined. It was established that the crushing probability depends on the grain size of the feed (Y) and the gap size (s), so the breakage probability S, for each cone crusher, can be well characterised by the function formed using the ratio of these two parameters: SfYsf==. The distribution of the broken grains can be described reliably using the relative grain size distribution function B(? = x/Y) (usually Schuhmann-Gaudin- or Rosin-Rammler-shaped function). For the screens, the probability function ()2()111/NTx = xd ???---???? is suitable for cha-racterising the separation (where x? grain size, ?-open-area ratio, d ? rectangular screen aperture size, N ? number of appearance of the particle on a screen surface). Using these functions, the comminution circuits were described by means of vector/matrix equations. The calculations and measurements verified the reliability of the developed models and algorithms.

Jan 1, 2014

By N. Pradhan

In the Sukinda valley, Orissa, India, a large quantity of overburden material is generated during the mining of chromite mineral (on average 10 tons for every ton of ore). The overburden hereby depicted as ?lateritic nickel ore? contains on an average 0.5% Ni. IMMT Bhubaneswar is working on this material for extraction of nickel and cobalt. But for better recovery of metal values, thermal activation or thermal reduction of ore is required. An alternative biotechnological route for reduction of ore is hereby attempted. An anaerobic dissimilatory Iron (III) reducing bacterial consortium (here denoted as IRB), capable of imparting iron phase changes in the lateritic nickel ore was established which improves the subsequent extraction of co-precipitated Co (III) and Ni (II) from the ore. In this study, properties of thermally and microbially reduced lateritic nickel ore are compared vis-à-vis original ore. Due to the phase changes, original light brown color of the lateritic nickel ore changes to dark brown on IRB treatment. This dissimilatory reduction of ore leads to formation of some magnetic particles, which were separable by hand held magnet. Roasting and IRB treated ore on acid leaching with H2SO4 show about 45 % and 36 % leaching of nickel ore compared to about 18 % leaching from the original lateritic ore. If bacterial reduction method is successful, cost intensive method of ore roasting process can be eliminated. Thus, it is possible to make use of dissimilatory iron reducing bacteria for recovery of valuable metals from off grade iron ore/ laterites. Keywords: lateritic nickel ore, bacterial reduction, thermal reduction, dissimilatory fe (iii) reducing bacteria

Sep 1, 2012

By J. S. S. Allwin Ebinesar

The bioremediation of zinc was carried out using Pseudomonas alcaligenes, a Gram negative heterotroph. The parameters such as pH, bacterial cell number, initial metal concentration, and interaction time on the biosorption of zinc were studied. The maximum zinc uptake was found to be about 95% at pH 5 and biomass loading of 2.7x1010cells/mL. The biosorption isotherm for zinc exhibited Langmuirian behavior and the Gibbs free energy of biosorption was determined to be -31.2 kJ/mol, indicative of coordination of zinc with the functional groups on the bacterial surface. The adsorption kinetics followed a pseudo-second order equation. FTIR and EDAX studies confirmed the interaction of zinc with the biomass. The mechanisms of metal-microbe interactions are discussed.

Sep 1, 2012

By M. Mirnezami

Pentlandite samples were obtained as Ni concentrate from three Canadian plants and one specimen sample from Ward?s Scientific Establishment. The samples were upgraded using gravity and magnetic separation techniques. Nickel concentration was determined by atomic absorption spectroscopy. Microprobe analysis identified a range in Co and Cu lattice substitutions. All samples exhibited similar zeta potential-pH trend with isoelectric points from 2 to 3, and similar responses to copper activation and addition of xanthate. The similar trends indicate that the variations in lattice substitution identified have no significant effect on electrokinetic properties; that is, samples from any source likely yield results that can be generalized.

Sep 1, 2012

By N. Panteleeva, E. Konoplev, I. Michailova, S. Titkov, S. Aliferova, T. Gurkova, T. Chumakova

Cationic flotation using alkylamines and their derivatives as collectors, and characterized by high selectivity of mineral particle separation, is finding ever growing industrial application. In recent years the industrial application has been initiated of new cationic collectors - alkylmorpholines. Efficiency of cationic surfactants operation as collectors is dependent upon their colloid and sorption properties and the availability of silicate .carbonate rock-forming mineral impurities in the ore, which sorb the cationic collector. Investigations have been carried out on the influence of frothers and organic depressors with various compositions upon physical-chemical and flotation properties of alkylamines and alkylmorpholines. On the basis of these investigations requirements for organic depressor were developed and new flotation reagents were proposed (V-1 frother and KS-MF depressor). The use of new reagents enables one to decrease considerably the consumption of expensive cationic collectors and to enhance the floatability of coarse mineral particles. Data of new reagents industrial application is presented. The reagents developed can be used for flotation processing of other ores.

Jan 1, 2003

By S. Castro

Molybdenite flotation is strongly depressed at pH higher than 9.5 in the flotation of Cu-Mo ores in sea water. Chemically sea water contains mainly Na+ and Cl- ions, but also some secondary ions, such as SO42-, Mg2+; Ca2+, HCO3-; etc., which are not necessarily indifferent for the flotation of molybdenite. The natural floatability of molybdenite in sea water and in NaCl solutions containing different secondary ions is investigated by micro-flotation tests. The tests indicate that the floatability of molybdenite in alkaline media in 0.6 M NaCl solutions is not affected by the presence of anions, such as, SO42- and HCO3-, at concentrations similar to those occurring in sea water. However, a strong depression of molybdenite at pH ranging from 9.5-10.0, is produced by the alkaline earth metal cations (Ca2+ and Mg2+ ions), dissolved in distilled water or in 0.6M NaCl solutions. It was found that effect of Mg2+ions is significantly stronger than Ca2+ ions. Effect of both ions is attributed to hydrolysis and adsorption of MOH+ hydroxy-complexes. This is followed by subsequent precipitation of hydrophilic colloidal hydroxides at the molybdenite/solution interface, and in bulk solution.

Sep 1, 2012

By Wei Qu, Yongsheng Song, Xingyu Liu, Wenjuan Li, Shuang Liu, Guiying Zhou, Bowei Chen

The Pb,Sb,Zn multi-metal sulphide ore is processed in sequence of beneficiation of jamesonite, sphalerite . Due to relative large amount of collector (xanthate), activator (CuSO4) and regulator (lime) during different flotation stage, the flotation wastewater from sphalerite beneficiation stage can’t be directly recycled to the first lead flotation stage. In this paper, the flotation wastewater from sphalerite beneficiation stage was treated by Ozone and BAC technology, results showed that when the influent concentation of COD and copper ion were 850 mg/L, 10.48mg/L respectively, the Ozone and BAC technology could effectively treat such type of water. In the treated wastewater, the COD is 60mg/L, copper ion concentration is 0.023mg/L, pH is 7.0, which satisfy the need of Pb,Sb-Zn preferential floatation separation process. After recycle of the treated wastewater to Pb,Sb floatation circuit, qualified Pb,Sb concentrate and Zn concentrate were obtained.

Jan 1, 2014

By Josefin Lannefors, Anders Klingberg, Natalija Gorochovceva

"Development of new anionic collectors becomes more and more important. This can be explained, on the one hand, by the fact that over the years phosphate ores have become more fine grained and complex (example weathered). On the other hand, a development with a focus on sustainability (sustainable development) of new anionic surfactants is required by authorities and society. Within the sustainable development several characteristics of a collector have to be taken into an account: efficiency, selectivity, froth characteristics, environmental profile, raw materials used for the synthesis, manufacturing complexity, stability upon storage, etc.Several anionic surfactants based on ester and amide chemistry were synthesized, characterized and used as flotation agents for calcium phosphate containing ore. The surfactants were used in a formulation together with other anionics, since in a pure form, during the flotation, they did not provide right froth characteristics.A new anionic collector/formulation was developed, that fulfills all above listed requirements."

Jan 1, 2014

By Tchingis Lekhatinov, Lev Filippov, Vyacheslav Severov, Alexandre Matinin, Victor Samyguin, Inna Filippova

"Comparison of flotation efficiency of the new multi-zone flotation cell (MZFC) and different conventional cells was carried out at lab and pilot scales on the various samples: high contrast pyrite tailings and old copper containing tailings. MZFC is a cell of intensive flotation, which provides optimal hydrodynamic conditions for all flotation sub processes. Enhancing of particle attachment, creation of conditions for coalescent flotation, selection of spatially separated zones according to optimal hydrodynamic conditions for flotation sub-processes are proposed as main principles to design an MZFC. The bubbles/pulp stratification was pointed out as a limiting step in the existing intensive flotation machines. Two strategies to improve bubbles/pulp stratification in the MZFC were studied: (a) impact of pulp-bubble jet to the surface of a prismatic insert inside of cell, which provides the detachment of low hydrophobic particles from bubbles, and (b) profiling the pulp/bubbles jet from the reactors due to a specific geometry of cell walls. The new continuous MZFC devices were demonstrated similar or higher efficiency in comparison with laboratory batch flotation cells for pyrite flotation. Higher flotation efficiency (82%) with pure pyrite concentrate (51.2% of sulfur) and a recovery level of 92% was obtained in MZFC when the cell with stratification by impact was used. Similar results were obtained with old Cu-containing tailings. Although MZFC had 1.5 times greater yields of concentrate than a batch flotation cell, it provided the increase of chalcopyrite recovery by 29.4% and concentrate grade by 4.8%. An original organization of pulp/bubbles stratification in the separator part of the new intensive flotation machine using variable geometry inserts allowed the best flotation selectivity with a bubble mineral loading coefficient 1.5 fold higher than the laboratory mechanical or pilot cells."

Jan 1, 2014

By Y. M. Zhu, G. C. Gong

"The influences of citric acid (CA) on the flotation behavior of cassiterite using styrene phosphonic acid (SPA) as the collector were studied via single mineral flotation tests, contact angle measurements, zeta potential determinations and solution chemistry calculations in this paper. The results of single mineral flotation tests revealed under the conditions that pH=4 and the dosage of SPA 100 mg/L, the recovery of cassiterite reached 76.78%. The addition of 20 mg/L AC decreased the recovery by 12.42% at pH=4. Contact angle measurements demonstrated the adsorption of CA prior to SPA made the cassiterite more hydrophilic. The results of zeta potential determinations and solution chemistry calculations indicated the chemisorption of C6H7O7- and C6H6O72- filled parts of the Sn site on cassiterite surface and prevented the SPA from getting adsorbed. The hydrophilic effect of AC was stronger than the hydrophobic effect of SPA and the flotation of cassiterite was crippled. INTRODUCTION Tin is an important metal which is widely used in medical instruments, marine engineering materials, electronic and electrical devices, welding, weapon manufacturing and organotin compounds industries (Angadi et al., 2015). Cassiterite is the only mineral from which the tin can be extracted, thus it is of great importance to efficiently exploit the cassiterite mineral. Flotation is an indispensable method for the recovery of cassiterite (Li et al., 2015). However, cassiterite is usually in association with many other gangue minerals which are of similar floatability, such as quartz, calcite, fluorite, iron oxide, wolframite, scheelite and tourmaline (Sreevinas, 1997). So some modifiers are necessary in the cassiterite flotation process. The amounts of the modifiers used in the flotation must be judicious and the overmuch modifiers may cripple the recovery of cassiterite (Parsonage et al., 1987). Nevertheless, the research about the effects of the modifiers on the flotation behavior of cassiterite has been rarely reported. In this paper, the influences of citric acid (CA) on the flotation of cassiterite using styrene phosphonic acid (SPA) as the collector were investigated by flotation tests, contact angle measurements, zeta potential determinations and solution chemistry calculations."

Jan 1, 2018

By Junji Shibata

In a present process to treat the tungsten carbide tool waste, the wastes are roasted in air and then an alkali leaching is carried out in an autoclave. An environmentally friendly process is required to recover rare metals (Co and W) from the wastes. The effect of mechano-chemical (MC) treatment on leaching of rare metals was investigated in this study. The solvent extraction and crystallization-stripping methods were applied to separate and recover tungsten and cobalt in the leached solutions. The MC treatment for the rare metal leaching is effective to dissolve rare metals from the wastes due to the change in crystalline structure of WC and oxidation of WC with KMnO4. Cobalt ions are extracted with D2EHPA by a cation exchange reaction. Tungsten in the leachate can be extracted by TOA (tri-octyl amine) as an extractant, because tungsten species exist as a form of anionic species in acidic solution. The rare metals in organic phase are recovered as insoluble salts such as oxalates and ammonium salts in the crystallization-stripping process. Keywords:unheated oxidation, solvent extraction, crystallization-stripping, recycling

Sep 1, 2012

By Ashish Kumar

High grade ore deposits in the world are fast depleting and the valuables in the low-grade ores are finely disseminated. The feed grade to flotation circuit is also declining. Attainment of suitable grind is preferred, which inevitably creates more fines of the gangue minerals to interfere with the flotation process because of the undue competition between the fines and the valuables for the collector ion adsorption. Besides the use of polymeric or long chain hydrocarbon depressants for the gangue mineral, microbial induced flotation also has potential to float minerals selectively. Thiobacillus ferroxidans and Thiobacillus thiooxidans adhere on the minerals to modify its surface properties and affect the minerals flotation acting as depressants. Hindustan Zinc has conducted laboratory studies to understand the adhesion of microorganism on the mineral surfaces and its impact on the selective flotation. The experiments were further designed to reduce consumption of depressing reagents for graphitic carbon, pyrite, and galena. Preliminary studies reveal that desired quality of concentrate can be achieved with reasonable recovery. Keywords: thiobacillus thioxidans, thiobacillus ferroxidans, bioflotation, microbial induced flotation

Sep 1, 2012

By Sirish L. Shah

It is now common to have archival history of thousands of sensors sampled every second over long time. Yet we frequently have process engineers complain:??.We are drowning in data but starving for information??. How can these rich data sets be put to use? This paper addresses the issue of information and knowledge extraction from data with emphasis on process and performance monitoring including fault detection and isolation. Most of the major plant, factory, process, equipment and tool disruptions are avoidable, and yet preventable fault detection and diagnosis strategies are not the norm in most industries. It is not uncommon to see simple and preventable faults disrupt the operation of an entire integrated manufacturing facility. For example, faults such as malfunctioning sensors or actuators, inoperative alarm systems, poor controller tuning or configuration can render the most sophisticated control systems useless. Such disruptions can cost in the excess of $1 million per day and on the average they rob the plant of 7% of its annual capacity. Over the last decade the fields of multivariate statistics and data visualization and analysis methods have merged to develop powerful sensing and condition-based monitoring systems for predictive fault detection and diagnosis.These methods rely on the notion of sensor fusion whereby data from many sensors or units are combined with process information, such as physical connectivity of process units, to give a holistic picture of health of an integrated plant. Such methods are at a stage where these strategies are being implemented for off-line and on-line deployment. This article attempts to outline the field of sensor fusion - the application of signal processing methods, in the temporal as well as spectral domains, on a multitude and NOT singular sensor signals to detect incipient process abnormality before a catastrophic breakdown is likely to occur Keywords: Process analytics, process and performance monitoring, multivariate statistical analysis, sensor-fusion

Sep 1, 2012

By M. Saghaeian, R. Hejazi, L. Hosseini, M. Zare

Difference between plant feed specifications in practice and design feed is a problem that most of processing plants face during operating and commissioning. This topic has led to inappropriate operating and necessitates repeating the basic tests on new feed. Gol-E-Gohar fourth concentrate line with a capacity of 2 MTPY, located in Kerman province, is the first iron concentrate plant in Iran in which High Pressure Grinding Roll (HPGR) technology has been applied. Plant&apos;s feed consists of 30% AG mills pebbles of lines 1-3 and 70% run of mine crushed ore whose Fe=51%, Fe/FeO=2.5, S=1.7% and work index=15 kWh/t. Desired concentrate has Fe>68% and S<0.7%. After the plant construction and operation commencement, providing design feed was not possible due to the crushing unit`s not being complete, therefore the plant was fed by AG mills pebbles. For predicting optimal conditions of the plant and investigating the possibility of improving the current concentrate specifications, sampling from the new feed and laboratory and pilot tests was performed again. Studies showed that new feed has Fe=41%, Fe/FeO=3.5, work index=17 kWh/t. Results of laboratory tests with Davis tube device and pilot tests run using magnetic separators with simulating the plant`s circuit showed that with current feed, achievable recovery in industrial scale would be 75.52% which compared to plant&apos;s recovery in studied period (75.94%) shows that plant operated in optimal conditions. To improve the current concentrate specifications (Fe=66%, S=1.03%, Ferec=75.94%) and for achieving desired concentrate, samples were reground to four fractions with k100= 300, 212, 100, 45 and Davis tube tests were performed on each of the samples separately. Results showed that the fraction whose k100=212 µm or k80=200 µm has respective Fe and S grades of 68.27% and 0.681% which are consistent with the desired concentrate.

Jan 1, 2014

By Morin D. H., Battaglia-Brunet F., D'Hugues P.

"In the mineral-processing field, bioleaching of metal sulphide concentrates is currently operated in very large mechanically agitated tanks. Such bioreactors have considerable requirements in terms of power consumption for mixing, aeration and heat transfer. The use of slurry bubble column, where the particles are suspended by gas motion as well as by liquid upward flow, could be an alternative to achieve bioleaching in more economical conditions. In order to compare these two techniques, a unit of stirred reactors in cascade and a bubble column were comparatively operated at laboratory scale in the bioleaching of a pyrite concentrate. For both pieces of equipment, experiments were performed not only in batch mode but also in continuous conditions.Bubble column performances were significantly affected by unpredictable technical difficulties met to maintain continuous feeding in the bubble column and by a significant settling of the heavy solid particles. Nonetheless, theoretical kinetic data, extrapolated from results in batch conditions, could be compared to those obtained in continuous tests, in bubble column and in mechanically agitated reactors. These kinetic data were used to evaluate the influence of reactor design and configuration choice on bioleaching performances."

Jan 1, 2003

By K. Haga

In this study, flotation tests were performed to investigate behavior of enargite and chalcopyrite ores from different sources synthetically mixed for separation of enargite. Flotation parameters including; pH, reagents concentration and type and flotation time were controlled to obtain an enargite concentrate with high As and chalcopyrite concentrate and final tailings with As content below 0.5 mass%. The copper ore bearing enargite mineral contained 5.87 mass% As and 16.50 mass% Cu while the chalcopyrite bearing ore contained 0.32 mass% As and 21.63 mass% Cu. The two ore samples were mixed at 7:3 (enargite: chalcopyrite) by weight ratio to prepare a mixed ore sample with arsenic content at 3.16 mass% and 18.25 mass% Cu for the flotation study. For enargite single ore flotation, the 38?75 µm size fraction showed that over 98% enargite was selectively recovered within 5 min at slurry pH of 4.0 and arsenic content in the final tailings was reduced to 0.22 mass%. In mix ore (enargite+chalcopyrite) flotation, 97% of enargite was first removed at pH 4 followed by chalcopyrite flotation at pH 8, and over 95% recovery was achieved in 15 min flotation time. Arsenic content in the final tailings was reduced to 0.1 mass%.

Sep 1, 2012