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By B. Vasanthakumar

In this study, the effect of adaptation of B.subtilis to sphalerite and galena with respect to the selective flotation of sphalerite from the sphalerite-galena synthetic mixture has been examined. The changes in the surface charge of the mineral and the bacterium, cell wall components and the profiles of secreted proteins are discussed. The flotation recovery of galena increases with the increase in the adaptation cycle of B.subtilis to sphalerite and galena, while the flotation recovery of sphalerite is independent of the adaptation cycle with either mineral. From the gel electrophoresis analysis, the protein profile for the unadapted and adapted cells is found to differ distinctly and this may be attributed to varying molecular weight fractions arising from different growth conditions. Electrokinetic measurements showed shifts in the iso-electric points of not only B.subtilis but also of the chosen minerals after adaptation. Additionally, the zeta potential of B.subtilis is found to become less negative after bacterial adaptation to the chosen sulfide minerals, while it showed an increase in the magnitude of surface negative charge after various enzymatic treatments. The change in the surface morphology and cell wall components such as phosphate, uronic acid and acetylated sugars of the bacterial species during adaptation to sphalerite and galena has been assessed. Selective flotation tests on a synthetic mixture of galena and sphalerite confirm that sphalerite can be preferentially floated from galena in the presence of the insoluble fraction of lysed B.subtilis cells initially adapted to sphalerite, with a high selectivity index. Keywords: bioflotation, b.subtilis, mineral adaptation, sphalerite, galena

Sep 1, 2012

By A. P. Das

Biomining technology focuses on achieving effective recovery of precious metals from their ores and concentrates using microbial techniques. Biomineral extraction of manganese from low-grade manganese ores using bioleaching was investigated in this paper. Five fungal strains were selected for screening of bioleaching of low-grade Mn ore collected from Sanindpur iron and manganese mines, Koira Sector, Keonjhar, Odisha, India. A fungal strain, Aspergillus niger was selected as it showed high efficiency of manganese leaching. Growth of the fungus was determined in terms of sbiomass dry weight and the final pH was monitored. The selected fungal strain was used for bioleaching of low-grade manganese ore of -150µm size particle size at 2 % pulp density with 2g/100ml sucrose concentration for duration of 20 days. About 60 % of Mn bioleaching was obtained with A. niger. The fungal species proved to be useful for manganese biomining.

Sep 1, 2012

By Sharma K. K.

India is the third largest producer with accounting to fifth largest reserves base of coal in the world. Indian coal has high ash content (15-45%) and low calorific value. The basic processes being used in India at different places for coal washing adopts old techniques. Much of the valuable part is being lost during washing processes. With enhancement of the available techniques and use of new processes like flotation process indicates better recovery of carbon values during washing stage. The same will increase the reserve base, improve economy of operation and alleviate environment related problems. In the above backdrop this paper portrays the case study of an existing coal processing plant in India. The case study includes the modifications being incorporated in the existing process to enhance the product value. The existing practices and the future trend of process technology that could be adopted to meet the requirements in this country are also discussed. Keywords: washing, dense media cyclone, magnetite media, flotation

Sep 1, 2012

By Rasool Hejazi

The feed to Chadurmalu iron ore concentrator plant is a mixture of magnetite and haematite iron ore with a Fe/FeO ratio of about 8. The feed to plant, after grinding via wet SAG mill, is pre-separated by wet low intensity magnetic separator. Magnetic product is conducted to magnetite processing circuit for producing magnetite concentrate, and nonmagnetic product is directed to haematite processing circuit. Due to surface oxidization of magnetite particles and a decrease in magnetic attraction properties, significant amount of these particles are misled to tailing which results in decreasing the efficiency of haematite processing circuit. This problem can be remedied by using magnetic drum separator with more magnetic intensity and/or gradient. In this paper, the replacement of LIMS separators with wet medium intensity magnetic separators with a field intensity of 3800 gauss on drum surface (MIMS) have been suggested and considered as the most suitable solution to prevent the loss of magnetite particles. The results of carried out investigations with replacement of drum separators in industrial scale, showed that utilizing MIMS in magnetite processing circuit resulted in increasing final concentrate weight recovery on average by 2.59%, without any adverse effect on the concentrate quality; decreasing the magnetite content in the feed to high gradient magnetic separator (HGMS) by about 3.5%; decreasing the feed to floatation part by about 7% and consequently decreasing consumption of chemical reagents; increasing Fe/FeO ratio of the feed to plant. Keywords: iron ore, medium intensity magnetic separator, haematite, Chadurmalu

Sep 1, 2012

By Caitlin Rogers

The environmental and economic sustainability of froth flotation is dependent on effective management, which in turn improves the performance of a concentrator. In economic terms this means improved recovery of valuable minerals, in environmental terms this means effective management of acid generating tailings. Three indicators were selected to measure the performance of an integrated flotation system. The system consists of two stages of flotation; valuable mineral flotation followed by environmental desulfurisation by froth flotation. The suitable indicators were selected based on their fulfilment of four attributes. An attribute is a desired aspect of an indicator. The four attributes were: comprehensive, relevant, sensitive and quantitative. Two environmental indicators and one economic indicator were selected. They represent revenue generation from valuable minerals and environmental cost of management. The suitability of the selected indicators was shown using illustrative scenarios.

Jan 1, 2014

By Mingfei He, Yude Gao

"The leaching kinetics was studied during leaching of indium-bearing zinc oxide to recover indium. The effects of temperature, sulfuric acidity, particle size, stirring rate on dissolution rate of indium were investigated. Results showed that the leaching process was controlled by chemical reaction at the condition of low sulfuric acid concentration. While the acidity increased to 1.8 mol/L, the leaching process was transformed into an internal diffusion controlling model . The corresponding value of reaction orders under low acidity and high acidity were 1.194, 0.156, respectively. Further calculation results indicated that the leaching reaction activation energy was only 10.97kJ/mol under the condition of high acid. The leaching rate constant was inversely proportional to the square of particle size, while the effect of stirring rate on leaching process was insignificant. The leaching process can be enhanced by increasing the temperature and acid concentration, as well as the decrease of particle size. And a final kinetics eqution was proposed. KEYWORDS Indium, extration, leaching kinetics, zinc oxide INTRODUCTION Indium[1,2] plays an important role in many aspects of living and industrial production owning to its special physical and chemical properties. The reserve of indium is rare on the earth, and most of indium is distributed in some other minerals[3]. Some researchers [4,5] have proposed that indium mainly substitutes for the lattice of other minerals by isomorphous. Therefore, the extraction of indium should take into account of the production technologies of those minerals to comprehensively recover the valuable metals."

Jan 1, 2018

By T. C. Alex

Mechanical activation of gibbsite [?-Al(OH)3] is the theme of this paper. Industrially prepared gibbsite used in the study has a mono modal size distribution with a median size, d50=110 µm. Mechanical activation of this gibbsite has been carried out in a planetary mill at ambient conditions. Mechanical activated gibbsite samples are characterised in terms of particulate characteristics, structural characteristics and reactivity. As a result, of milling, mono modal size distribution of the unmilled gibbsite changes to a broad multimodal distribution. Size reduction has been sharp in the initial stages of milling; median size reduces to ~7 µm during 15 min of milling. Thereafter no decrease in median size is observed; rather it is found to increase gradually with further increase in milling time, indicating particle aggregation. Morphological studies of milled gibbsite have shown that the platelets forming the agglomerate are separated first; the separated platelets then undergo breakage. Aggregation of particles sets in the later stages of milling as a result of increased surface area and surface energy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies have clearly revealed the changes in gibbsite structure during milling. Analyses of XRD data show that the crystallite size of gibbsite decreases as the milling time progresses whereas its microstrain is found to increase. Accumulation of energy in the structure is the result in both cases. TEM micrographs with signs of defects leading to disordering of gibbsite structure complement the XRD results. Reactivity of milled gibbsite, decrease in its deydroxylation temperature and increase in alkali dissolution, is found to increase with mechanical activation. Increased reactivity of milled gibbsite is found to have a strong correlation with the BET specific surface area. Keywords: mechanical activation, gibbsite, alkali dissolution, thermal dehydroxylation, reactivity

Sep 1, 2012

By Peter Ay, Vincenz Mehlstaubl, Satyanarayana Narra

"This study gives an insight into non-destructive testing methods suitable for porosity analysis at a small scale, firstly summarizing relevant state-of-the-art technology and pending patents, secondly realizing and documenting the start-up of the VHX-2000 digital microscope by the manufacturer Keyence and thirdly demonstrating practical application with the extended analysis of three fundamentally different agglomerates for which important application-related parameters are determined. Various analysis procedures on the different agglomerates the efficient and timesaving operational features of the digital microscope are outlined. Firstly an analysis of flax fibre agglomerates determines the process conditions best suited to produce agglomerates with specific properties by determining sphericity, cubicity, density and porosity as well as fibre damage and alteration. Secondly the production of iron-hydroxide - hemp-fibre agglomerates serves to obtain information on porosity values as a result of a cauterization of the fibres. The third analysis provides estimations of porosity values for acid-treated lignin agglomerates. Measurements were carried out with compact dry agglomerates and with soaked, expanded agglomerates, determining factors for total water carrying capacity. Practicability of non-destructive testing by digital microscopy is demonstrated and explained concerning the applications in this study by obtaining definite structural findings about the analysed agglomerates. Information on its operation is made available by a practice-oriented manual for the VHX-2000 digital microscope. Further suggestions for more in-detail analysis results with different instruments are given."

Jan 1, 2014

By Ljudmil S. Grigorov, Eric Forssberg, Hanumantha Rao Kota, Robert J. Pugh, Lidia B. Alexandrova

"We have used the microscopic thin balance developed by Scheludko at al. (1970) technique to study the stability and interactions within the thin film between the silica surface and air bubble with (i) a long chain C10 amine and (ii) a cationic/anionic surfactant systems consisting of mixtures of a long straight C10 chain amine with long straight chain C8, C10 and C12 sulfonates. It was found that the mixed surfactants caused lower contact angles, lower rates of the thin aqueous film rupture and longer film lifetime, compared to the pure amine system.This behavior was explained by the initial strong adsorption of positively charged interfacial complexes from the mixed surfactant system at the air/solution interface followed by adsorption at the silica interface. It was also shown that the chain length compatibility between the anionic and cationic surfactants controls the strength of the interfacial complex, determining an inhibition in the thin film rupture and dewetting of the film. The rupture mechanism was explained by an earlier established heterocoagulation mechanism between the positively charged air/solution interface and the solution/silica interface which remained negatively charged. The formation of the interfacial complex at the air/solution interface was confirmed by using surface tension data."

Jan 1, 2003

By Arun Appadurai

Pneumatic transport systems play a vital role in conveying discrete particles over a sizable distance with minimal energy consumption. However if such a system is not designed keeping particle physics in mind, it leads to intractable problems which could possibly assume dangerous proportions, including but not limited to expensive redesign of the entire system. This paper describes a novel method, which harnesses the powerful technique of Computational Fluid Dynamics (CFD) to investigate a problem occurring in rotary kilns using coal as a major fuel source. In some of the sites, a unique phenomenon of abnormally high CO emission was observed and owing to the highly random nature of occurrence, it was difficult to scientifically investigate the problem and its cause. Most of the published solutions for the high CO problem tend to concentrate on the incomplete combustion aspect of the kiln and resolve the situation by increasing the air supply thereby improving the stoichiometric ratio of combustion. This paper offers an alternate correlation that relates high CO emissions to the phenomenon of coal delivery fluctuations caused by the sub-standard operation of the coal transport system. A CFD model for the coal delivery pipe is validated by utilizing the actual process data sourced from the measurements taken from a functioning plant. The results of the model are used to derive correlative conditions that point to the unstable operating conditions of the coal delivery pipe prevalent in the industry. The conclusions are summarized into a series of recommendations for optimized design of coal delivery systems which are implemented in a pilot plant. The results irrevocably prove a statistically significant reduction in CO emissions without resorting to increased air supply and power consumption. Keywords:CFD, Pneumatic Conveying, Saltation Velocity, Particle Flow

Sep 1, 2012

By Ahmad Amini, Hadi Abdollahi, Pouya Karimi

Due to detrimental effects of cyanidation process on the environment in gold industry, application of cyanide alternatives such as thiourea are being highly considered in recent projects. In this study, the extraction of gold from poly metal ore, using thiourea was precisely investigated. The representative sample contained 2.5 ppm Au and 160 ppm Ag. The sample was categorized as oxide gold ore, because the main part of its pyrite was changed to iron oxide and hydroxide such as goethite and lepidocrosite. According to mineralogy, the main gangue mineral was quartz. It shows that gold grains are free and interlocked with quartz matrix. Also, the presence of a high amount of silver in free and sulfide forms and also the low content of other sulfide minerals such as base metal sulfides is a remarkable point of these studies. In the gold extraction process with thiourea, there are several parameters that affect the rate of gold dissolution such as concentrations of thiourea as a gold lixiviant and ferric sulfate as an oxidant, pH and size fraction of feed and leaching time. The influence of these parameters on the gold dissolution rate were investigated and optimized. The results showed that the concentration of thiourea is the most influential parameter which could increase the gold recovery to 71% (at 10 g/kg sample). The optimal amount of ferric sulfate was determined as 6 g/kg sample. Also, the optimal levels of size fraction of feed and pH of solution were 88% under 75 micron and 2 as acidity; respectively. Leaching time was 6 hrs. In addition, this sample was leached with cyanide and the optimized values of size fraction of d88=75 microns, pH=10.45, 2500 ppm of sodium cyanide with time leaching of 24 hours were concluded for maximum recovery of gold in solution. Finally, the results of cyanidation tests were compared to the thiourea dissolution after optimizing all affected parameters in cyanidation process.

Jan 1, 2018

By X. Y. Zeng

Most Chinese titanium bearing minerals are the composition of magnetite vanadium and ilmenite. All of such mineral processing plants use low intensity magnetic separators to recover magnetite and vanadium goes with magnetite. In the past years most of the plant tails containing about 10% TiO2 were abandoned. Now many of these plants use SLon magnetic separators to recover ilmenite in the roughing stage, which can throw away most of the gangs and slimes with very low cost. The new development of applications of SLon magnetic separators in Chinese ilmenite processing industry is introduced in the paper.

Jan 1, 2014

By Ana Elisa Casas Botero

The Rhodococcus opacus microorganism was evaluated as a biocollector for flotation of barite. The electrophoretic behaviour of the mineral, before and after R. opacus interaction, was evaluated and showed that the cells adhesion shifted the mineral zeta potential curves. Adhesion tests were suggested a high affinity of the bacteria for barite. The experiments of the adsorption rate of the R. opacus on the mineral surface showed fast kinetics, achieving a maxim of cell adsorption after 5 minutes. Adsorption isotherm curves for barite could be categorized as Langmurian (L) type II. The best bioflotability results for barite achieved values around 75% for a R. opacus concentration of a R. opacus concentration of 250 ppm in the pH around 5.0. The studies were compared with the flotation of barite using a traditional collector. The bioflotation experiments were discussed considering the obtained adhesion tests. The results were supported by the Thermodynamic approach for selected pH values. The fundamental flotation studies showed the paramount potential that R. opacus presents as a biocollector and its possible application in the mineral flotation industry.

Jan 1, 2014

By Chi Zhang, Junyi Wu

"With the increasing popularity of lithium cobalt oxide in lithium ion battery industry, which is driven by new energy vehicle and mobile device applications, the demand of cobalt is also growing rapidly in recent years. There is a significant trend of increasing investment on cobalt capacity in China, and the automation renovation is considered as an option of improving production efficiency. This study aimed at evaluating the practicability of stainless permanent cathode blank and automatic stripping process in cobalt electrowinning process. The purpose is to replace the old starter sheet process in cobalt electrowinning, which so far was used by most of cobalt refineries in China, but very labor intensive and exposed operators to serious aerosols that contained both cobalt and acid. In the old starter sheet process, the initial cobalt starter sheet is produced onto a plate made of titanium, while the titanium cathode blank and hanger bar fit the critical corrosive environment but is lack of mechanical strength for automatic production which has been mature in copper electrowinning process. To evaluate the proper materials instead of titanium, the coupon corrosion tests with different raw materials including 316L and other stainless steel grades were held for several months in production environment at a cobalt tank house in China. Following the comparison between titanium and other tested materials, a pilot production test in a cobalt tank house is also on-going.INTRODUCTION Cobalt has been known in early China and used in pottery glazes, and the ancient Greeks and Romans used its compounds to make colored glass since long time ago. The blue on the colored porcelain from the Tang Dynasty in China was also due to the presence of cobalt compounds. The word cobalt is known being derived from the German kobalt, from kobold meaning ""goblin"", because the cobalt-bearing blue ore, CoAsS, was called kobaltin in Europe in the Middle Ages, it may have been thought to be harmful to the health of the miners because of arsenic in the ores."

Jan 1, 2018

By Andrzej Luszczkiewicz, Tomasz Chmielewski, Jan Drzymala, Andrzej Konieczny, Rafal Kaleta

Properties of the sedimentary Polish copper ore mined from the Legnica-Glogow Copper Basin (SW Poland) by KGHM Polish Copper S.A. were presented and currently used beneficiation technologies were described. Due to a unique lithological layered structure of the polymetallic deposit and existing mining system, the ore currently processed in the three KGHM concentrators is very complex with variable content of the carbonate, sandstone and shale fractions. The mined copper ore contains from 0.8 to 1.8 % Cu and Ag, Pb, Zn, Ni, Co, V and Mo as accompanying metals. The paper presents difficulties in upgrading the LGOM ore and selected possible solutions and development concepts of its processing. The first one is a chemical treatment with controlled amount of sulfuric acid of special product of flotation such as for instance middlings. The acid treatment leads to increased liberation of copper minerals and better further processing. Another concept is atmospheric leaching in oxygenated sulfuric acid and ferric ions solution as the major unit operation applied to selected low grade final flotation concentrates or flotation by-products. The third approach, based on copper ore pre-flotation with a frother to partially remove Corg, is also considered.

Jan 1, 2014

By Z. F. Dai

The Thompson Nickel Belt, located in Northern Manitoba, Canada, contains more than 400 million tonnes of ultramafic low-grade nickel mineralization in 9 deposits. One of these, the Pipe deposit, was mined between 1971 and 1983 producing a Ni concentrate of 9% to 11% grade at 73% recovery. The operation was terminated because the poor recovery, low Ni grade and high MgO con-tent of the concentrate made processing this ore uneconomical at the metal prices prevailing at that time. Vale Inco is now re-evaluating these deposits with the intent of providing a new source of concentrate for its Thompson integrated processing facility. It is known that serpentine slimes coating on the sulphide surfaces are responsible for the poor metallurgy. Various desliming methods were tested including settling, elutriating, tabling and hydrocycloning. Hydrocycloning has proven to be the most effective means of desliming. With a feed assaying 0.70% Ni and 33% MgO, a rougher flotation concentrate assaying 22.7% Ni and 4.8% MgO was produced at a Ni recovery of 62.5% (relative to the feed to grinding), with no utilization of slimes dispersants. Another 16.6% Ni recovery was achieved in scavenger flotation resulting in a total Ni recovery of 79.1%. Batch flotation tests using various flowsheet configurations to optimize the grinding, desliming, reagentizing and flotation conditions are in progress.

Jan 1, 2014

Vanadium-titanium magnetite from Panzhihua was crushed with open and closed circuit process by high pressure grinding roller (HPGR). The particle size characteristics of the crushed product were analyzed and the micro-cracks generated by HPGR during the crushing process were studied. The results showed that, in crushed products, the reduction ratio increases and the size distribution becomes more uniform with increasing of the pressure on roller?s surfaces. The fine fraction content of crushing products from -3.2 mm classification closed-circuit by HPGR increases obviously compared with that by Jaw Crusher and particle size distribution is more uniform. Large amount of intra-crystalline cracks and cleavage cracks are generated in vanadium-titanium magnetite crushed by HPGR, which makes the specific surface area larger and Bond grinding work index (objective particle size is 0.074 mm) decreased by 14.05% than that by Jaw Crusher. And the liberation degree of monomer of the product crushed by HPGR increased compared with that by Jaw Crusher with the similar fineness of grinding. Keywords: iron ore, high pressure grinding roller, micro-crack

Sep 1, 2012

By N. Tsoni

The separation and recovery of fine and ultra-fine particles during the processing of mineral commodities by conventional separation methods is difficult and inefficient. This is due to the problems posed by the very small size of the mineral particles. The fine and ultra-fine mineral particles are either generated during size reduction processes or are necessitated by liberation size. This problem is expected to deteriorate, as deposits of even lower grade are processed. The inefficiency of the conventional separation methods with regards to the processing of very fine particles leads to the loss of considerable quantities of mineral commodities to the tailings. Novel methods and techniques as well combinations of known methods have been tested over the years. Among them, selective aggregation, along or in combination with flotation, has been given much attention. This study deals with the application of hydrophobic agglomeration as a separation method for very fine particles. The selected mineral system is magnesite/quartz, due to its sensitivity to physi-cochemical separation methods. The aim was the selective agglomeration of magnesite using sodium oleate. Tests on single minerals revealed that separation seems feasible and efficient. The parameters examined were: pH, quantity of sodium oleate, conditioning time, and, finally, settling time. Tests carried out on artificial mixtures of the two minerals, under various proportions, confirmed the results obtained from single mineral tests but they were slightly inferior. Finally, hydrophobic ag-glomeration tests were carried out on single and artificial mixtures of minerals using sodium oleate and petroleum as reagents. The results show that the addition of petroleum improves the results. In conclusion, hydrophobic agglomeration can be applied successfully even for fine particles of difficult-to-be-separated systems such as magnesite and quartz.

Jan 1, 2014

By D. Govender

Theoretical flotation models suggest that there is a positive relationship between bubble-particle collision rates and turbulent kinetic energy dissipation. Fine particle flotation performance is generally enhanced by increased collision frequency and hence higher energy dissipation. Contrarily, increased turbulence in the rotor-stator region is related to higher detachment frequency of the coarser size range. Therefore, the optimal modes of recovery for the ?fine? and ?coarse? size classes are diametrically opposed. Industrial applications have previously confirmed that applying greater power to flotation slurries yields significant improvements in fine particle recovery. However, recovery of the coarser size class favors a different flotation environment. An improvement in the kinetics of the fine and coarse size classes, provided there is no adverse metallurgical influence on the intermediate size ranges, is obviously beneficial to the overall recovery response. Managing the local turbulent kinetic energy dissipation, and hence the power imparted to the slurry, offers the benefit of targeting the particle size ranges exhibiting slower kinetics. FLSmidth recently introduced the practical implementation of this concept. In principle, it decouples flotation regimes where fine and coarse particles exhibit preferential recovery. In the case of naturally aspirated machines (Wemco®), it is referred to as Hybrid Energy Flotation? and incorporates at least three phases: ? Standard flotation machines (standard energy input, rpm, rotor size/type) at the beginning of the row, where flotation is typically froth phase limited and operational, and set-up parameters have a limited influence on the recovery. ? Higher-powered flotation machines (high rpm, high power rotor size/type) at the end of the row to improve fine particle recovery. ? Lower-powered flotation machines (low rpm, low power rotor size/type) to enhance coarse particle recovery. In evaluating the effect of turbulent kinetic energy on flotation performance, the spatial distribution and its effect on size denominated recovery needs to be evaluated. The mean energy dissipation rate is a measure of the bulk energy input, but CFD-based models offer a more introspective view of flotation sub-processes. A CFD-based flotation model is used to highlight the effect of turbulent dissipation energy on attachment and detachment rates. Preferential collection zones for ?fine? and ?coarse? particles are predicted for both forced air and naturally aspirated machines. Keywords: CFD-based model, attachment, detachment, energy dissipation, hybrid energy flotation?, forced air, naturally aspirated

Sep 1, 2012

By H. Kasaini

Batch wise adsorption tests for platinum (Pt) on the surface of activated carbon pellets (Norit RO 0.8 BET surface area 1100 mg/g) were carried out in mixed chloride solution. The purpose of this study was to assess and compare the adsorption performance of amine-treated activated carbons (AACs) and native activated carbons (NACs) in terms of adsorption capacity and selectivity. The effect of pH and temperature on adsorption capacity and selectivity was established. The amine- treated ACs were prepared by anchoring the amino groups (butyl amines) on the surface of AC pellets in aqueous media and the UV-Vis was used to determine the amount of amine sequestered from solution by ACs. The dosage of butyl amine on the surface of ACs averaged 0.15 g/g, carbon. The adsorption mechanism was described by the ionization and complexation model whereby interaction between the protonated AAC surface and the anionic chlorocomplex ions (PtCl5 [H2O]-, PtCl62-) proceeded by either electrostatic attraction or/and by covalent bonding [(NH3)2PtCl6 or (CH2COO)2PtCl6]. By comparison, the adsorption capacities of Pt on amine-treated ACs and native ACs were 53.8 mg/g and 33.03 mg/g, respectively which highlight the benefits of anchoring functional molecules on ACs. The selectivity of AACs was influenced by solution pH. Pt adsorbed selectively on the surface of amine-treated ACs at pH<1.5. The highest separation factor that was recoded pertained to Pt and Fe species (ßPt/Fe = 90) then followed by Pt and Ni species (ßPt/Ni = 30) or Pt and Cu species (ßPt/Cu = 15). The lowest separation factor was recorded for Pt and Cr ions (ßPt/N= 5). Adsorption kinetics of Pt on amine-treated AC surfaces, according to the first and second order reactions, were investigated and results showed that rates were in the order 10= 5). -4 min-1 and 102 g?min/mg, respectively. The pseudo 1st order kinetics predicted the adsorption capacity of 51.81 mg/g which was almost similar to the experimental value (53.8 mg/g) while the second order rate equation predicted Pt adsorption capacity of 40.1 mg/g. Both The Langmuir and Toth isotherm fitted the Pt adsorption at pH < 1.0. The Freundlich isotherm tended to underestimate the adsorption capacity of AACs.

Jan 1, 2014