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By Stoyan N. Groudev, Ioannis Paspaliaris, Irena I. Spasova, Kostas Komnitsas

"Acid mine drainage waters generated in the uranium deposit Curilo, western Bulgaria, were treated by means of a constructed wetland located in the deposit. The waters had a pH in the range of about 2.5 - 4.1 and contained uranium, radium, some heavy metals (iron, manganese, copper, zinc, cadmium, cobalt, nickel, lead), arsenic and sulphates in concentrations much higher than the relevant permissible levels for waters intended for use in the agriculture and/or industry. The wetland covered an area of about 140 m2 and was characterized by an abundant water and emergent vegetation and a diverse microflora. Typha latifolia, Typha angustifolia and Phragmites australis were the prevalent plant species in the wetland but species of the genera Juncus, Eleocharis, Scirpus, Carex and Poa as well as different algae were also well present.The water treatment was started in July 2001 and until now (August 2002) the wetland effluents were characterized by pollutants concentrations decreased below the relevant permissible levels. The water flow rate through the wetland during this period varied in the range of about 0.2 - 1.0 l/s. The water clean-up markedly depended on the temperature but was efficient even in the cold winter months at air and water temperatures close to 0oC. The removal of pollutants was due to different processes but the microbial dissimilatory sulphate reduction and the sorption of pollutants on organic matter (viable and dead plant and microbial biomass) and clay minerals played the main role. Negative effects of the pollutants on the growth and activity of the indigenous plant and microbial communities were not observed."

Jan 1, 2003

By P. Huang

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

Sep 1, 2012

By Leopoldo Gutierrez, Esau Arinaitwe, Marek Pawlik

"The effect of various polymers, including: anionic carboxymethyl cellulose (CMC), polystyrene sulfonate (PSS), humic acids (HA) and non-ionic hydroxypropyl cellulose, on the wettability of Athabasca bitumen was evaluated through dynamic contact angle measurements using the captive bubble technique. The tests were carried out as a function of pH at a constant ionic strength (0.01 mol/L sodium chloride). The evolution of the three-phase contact angle between the solution, bitumen and an air bubble was followed as a function of time over a period of ~6 minutes. The contact angle data were modelled using a first-order kinetic equation. The results were analyzed in terms of the initial contact angle, the evolution rate constant, and the steady-state contact angle value. In the case of anionic polymers, a pronounced decrease in the initial contact angle value was observed at pH 3. Under acidic conditions, there was no significant effect of CMC observed on the steady-state contact angle value but PSS and HA significantly decreased the steady-state contact angle value. At pH 8.5. the anionic polymers did not affect the wettability of the bitumen surface but they significantly decreased the contact angle evolution rate. These results suggested that CMC is not capable of permanently lowering the hydrophobicity of bitumen, and the polymer only slowed down the evolution of the contact angle to the steady-state value. The results also showed that polystyrene sulfonate and humic acids were capable of making bitumen hydrophilic but only under acidic conditions. Only hydroxypropyl cellulose (HPC) produced a large decrease in the steady-state contact angle under alkaline conditions (pH 8.5). The kinetics of contact angle evolution in the presence of HPC was also drastically lowered. The results were discussed in terms of the chemical composition of the polymers and their different affinities towards the bitumen surface."

Jan 1, 2014

By A. A. Novoselov, U. Kelm

"Large volumes of mine tailings accumulated in surroundings of porphyry copper deposits represent a growing threat to environment. They contain significant concentrations of toxic metal and metalloids which can contaminate river runoff, ground waters or can be transported by wind. Both extreme pH of fluids in tailings impoundments and high surface areas of processed mineral grains provide their increased reactivity. As a result, during only a few decades, As, Cu, and Mo can be mobilized, redistributed through the tailing column and accumulated through post-deposition leaching, evaporation and contamination with natural fluids. Those processes are reflected in the forming of secondary minerals. Gypsum, Fe oxides/hydroxides, efflorescent salts and clay minerals are typical alteration products in tailings. Here we present the results of reactive transport simulations implemented on the base of PHREEQC and SUTRA codes. The one-dimension model emulates the mass balance between rainfall, evaporation and subsurface runoff, the kinetically- and thermodynamically-driven dissolution of tailing minerals, advective and diffusive transport of tailing fluids, and precipitation of secondary phases. A typical tailing column is composed of four unequal layers with predominance of (i) evaporation, (ii) secondary mineralization above, (iii) below water table, and (iv) near the bottom of dump. Those horizons are characterized by contrasting pH, chemical composition and bulk mineralization of pore fluids, distinct accessibility of atmospheric oxygen and, as a consequence, distinct intensity of sulfide oxidation. The modeling and its verification on Chilean tailings impoundments reveal the complexity and high rates of secondary mineralization. The accumulation of toxic alteration products is controlled by fluid transport through the tailing column induced by both rainfall/evaporation and exchange with subsurface runoff. The geochemical modeling is a powerful approach which allows comparing the processes in tailing deposits produced by distinct flotation regimes and providing the long-term predictions of their environmental impact as well as identifying sectors of tailings for possible re-processing."

Jan 1, 2018

By P. Somasundaran

Gangue minerals can often have severe adverse effects on selective value mineral separation. Such effects can be mediated through a variety of pathways or mechanisms. One popular mechanism is that of ?slime coating? or heterocoagulation, wherein the gangue mineral fines are believed to coat the value mineral surfaces and thereby reduce selectivity and floatability. Another pathway that has received relatively little attention is that mediated through the effect of gangue minerals on pulp rheology, and consequently selective separation. Our recent work in developing a scientific understanding of these effects has highlighted the prevalence and importance of this pathway. In this study, the impact of shape and morphology of serpentine gangue minerals on suspension rheology and selective Ni flotation from ultramafic ores was investigated. We found strong evidence for micro- and macro-network formation in the presence of acicular (needle-shaped) or fibrous minerals, which impacted pulp rheological properties. Results also supported the hypothesis that morphology has a greater role to play than mere shape. The size of the network ranged from 5 microns to 2 cm depending upon the amount and aspect ratio of fibrous minerals. These networks impede many flotation sub-processes, such as gas dispersion and bubble-particle interactions. Additionally, the small pore size of the networks prevents bubble penetration leading to a large transport of the gangue minerals to the concentrate via lifting of the entire network by bubble flux, which resulted in a significant grade dilution. Based on the scientific insights generated in this study various techniques have been developed to improve selective value mineral separation. Keywords: fibers, aspect ratio, microstructures, networks, pulp viscosity, gangue transport

Sep 1, 2012

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

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

Jan 1, 2003

By Kaiwen Liu

Activated carbon is widely used in the removal of organic and/or inorganic contaminants from waste water due to its high surface area, porous structure, and specific surface reactivity. However, in practical applications, it is difficult to recover the activated carbon completely by screening or classification. In this project,we prepared a magnetic form of activated carbon (magnetic activated carbon or M-AC) by precipitation of iron oxides on the surface of activated carbon. The M-AC can be easily separated from effluents by applying an external magnetic field, thus it can be recycled and regenerated for reuse. M-AC was characterized by X-ray diffraction (XRD), specific surface area measurement, and scanning electron microscope (SEM).XRD results show that the major phase of coated iron oxides on activated carbon is magnetite (Fe3O4). The specific surface area of activated carbon was found to be reduced after the impregnation of magnetite particles on the surface. The SEM micrograph shows the aggregation of the iron oxides on the surface of activated carbon. M-ACwas found effective in removing DETA (diethylenetriamine) species and metal ions from solutions. Cu (II) with initial concentrations from 5 ppm to25 ppm in solution is removed by more than 99% with the addition of 0.1 wt.%ofM-AC. For the removal of 25 ppm DETA species from solution, an addition of 0.5 wt.% of M-AC is required due to the larger size of the DETA molecule. Moreover, M-AC showed a good loadingproperty for nickel and gold ions from solutions. M-ACshows a better adsorption capacityover activated carbon and its potential applications in carbon-in-pulp for gold leaching and waste water treatment. Keywords: magnetic activated carbon (M-AC),diethylenetriamine (DETA),metal ion,adsorption

Sep 1, 2012

By G. H. Li

Preparation strontium carbonate with celestite concentrate by flotation is studied by agglomeration-reduction roasting process. It is shown that, the drop strength of green pellet is greater than 4 times?(0.5m) -1 under the balling conditions of moisture of 9% and time of 18~20min. Lignin xanthate obviously improves the ballability of the celestite concentrate due to the increase of surface hydrophilicity, therefore, the balling rate is increased, as well as green ball strength. The drop strength of 7 times?(0.5m) -1 can be obtained when the lignin xanthate dosage is 0.5%~1%. Reduction roasting with anthracite shows that the SrSO4 conversion is 82%~83% for celestite concentrate pellet, under the optimal conditions of roasting temperature of 1100~1150? and time of 30min, and it is 10% higher than conversion of celestite lump under the same conditions. The strontium carbonate are prepared after roasted pellets are leached, purified and carbonated, and the SrCO3 content is higher than 97% , while the content of CaCO3 is less than 0.3%.

Jan 1, 2014

By Rakesh Kumar, S. Mehrotra, T. Alex

"This paper, an overview of our recent findings on mechanical activation (MA) of minerals/materials, emphasizes the importance of sample genesis, mechanically induced/altered porosity and surface area, mineral interactions, glassy inorganic materials, surface alteration and zeta potential changes and, mechanically induced reactivity of solids. Materials investigated include Al-oxyhydroxides (gibbsite and boehmite), fly ash and granulated blast furnace slag. Planetary, attrition, vibratory and conventional ball mills are used for MA. Genesis of boehmite has been found to have a bearing on its behavior during MA. For example, BET specific surface area (SSA) of boehmite prepared by thermal dehydroxylation of gibbsite has decreased from 265 to 65 m2/g during 240 min of MA; in contrast, the SSA of hydrothermal boehmite has increased from ~2 to 36 m2/g. Mechanisms of surface area changes in the two boehmite samples differing in their genesis is explored. MA of gibbsite and its mixture with hematite/quartz using attrition milling has indicated that the presence of the second phase promotes amorphisation. Amorphous materials show signs of change in nature of bonding during milling as illustrated by MA of fly ash. Physicochemical changes during MA are not restricted to the bulk phase. The genesis of zeta potential changes in MA solids can be many; for example texture induced zeta potential changes as observed for gibbsite, while zeta potential changes during the milling of granulated blast furnace slag occur due to enhanced (possibly non-congruent) dissolution. Interesting manifestations of mechanically induced reactivity and its correlation with physicochemical changes are illustrated in terms of alkali leaching of boehmite and, hydration of MA slag. New findings reported here are associated with several open questions and are highlighted in the paper."

Jan 1, 2014

By Alejandro Uribe-Salas, Fabiola Nava-Alonso, Gloria Dávila-Pulido

This paper presents results of an experimental study performed on the role of calcium sulfate present in flotation water on sphalerite flotation in the Pb/Cu circuit (non Cu-activated sphalerite) and in the Zn circuit (Cu-activated sphalerite). In the Pb/Cu circuit calcium ions adsorb on the negatively-charged sphalerite favoring xanthate adsorption and therefore making sphalerite floatable; experimental measurements show sphalerite contact angle increases with calcium concentration while xanthate adsorption onto sphalerite increases with the increase of pH and calcium concentration. Gypsum (CaSO4·2H2O) eventually present due to calcium sulfate precipitation is not detrimental to flotation at this stage since it is negatively charged at pH 9 and therefore, does not adhere onto the surface of negatively-charged sphalerite. In the zinc circuit, Cu-activated sphalerite decreases its negative charge (or even becomes positively charged) and develops some hydrophobicity due to the polysulfide produced by Cu-activation. At this stage calcium ions do not interact with the mineral surface and therefore do not favor xanthate adsorption; nevertheless, precipitated gypsum particles do adhere onto the mineral surface, greatly affecting its floatability (e.g., contact angle). Addition of sodium carbonate to dissolve gypsum and to precipitate calcium as calcium carbonate, which disperses in the bulk of the suspension, effectively restores mineral hydrophobicity. SEM observations coupled with EDS analysis clearly illustrate and support the above sequence of events.

Jan 1, 2014

Spent automobile catalyst is an important secondary resource of PGMs (platinum group metals) and the recovery is significant. Various methods of recovery technology have been reported and applied in practical production, including pyro- and hydrometallurgical processes. Since the grade of PGMs in the catalysts is so low, approximately 0.5 wt. %, the present recycling technologies require high energy-consumption, it is of great significance to enrich the PGMs with some energy saving physical separation methods as a pretreatment. Automobile catalyst is usually composed of cordierite phase as a substrate and alumina phase, with PGMs, which covers the cordierite phase. We adopted the quenching pretreatment, one method of thermal shock, to generate micro-cracks between the two phases and separate the alumina phase from cordierite. Quenching was carried out by heating the catalysts in an electric furnace of different temperatures followed by rapid soaking into cold water. It was found that the phase boundary between alumina and cordierite was broken in the quenching and selective separation (detachment) of alumina from the cordierite could be achieved in the following surface grinding. The effect of quenching was checked by microscopic observation, hardness measurement, and chemical analysis. This paper figures out the stress formula of the quenching process, which is largely connected with layer thickness and temperature gradient by using an FEM (Finite Element Method) simulation and clarifies the mechanism of crack generation in the quenching process. Keywords: automobile catalyst, PGM, quenching process, FEM

Sep 1, 2012

By Valentine Chanturiya1

We have developed a classification of geochemical barriers according to their origin, i.e. natural and artificial, and according to methods and areas of application. There has been an examination of the interaction between different classes of geochemical barriers with sulfate solutions containing nickel, copper and iron. As natural barriers, carbonates (calcite and dolomites) were used. For artificial barriers, a mixture of serpentine and carbonatite, thermo-activated copper-nickel dressing tailings, and a magnesium-containing sorbent based on brucite was used. Keywords: geochemical barriers, physical-chemical geotechnologies, treatment of natural and waste water, recovery of nonferrous metals

Sep 1, 2012

By A. P. Wang

Porous carbon adsorbents derived from inorganic materials templates such as zeolite and mesoporous silicate attracted considerable attention in the last decade and got great progress in re-cent years. However, so far almost all of templates used in the process were artificial porous materials; the porous carbons prepared by this method are very costly, which restricts the synthesis and application of templated porous carbons. In order to reduce the cost of templated porous carbons, natural inorganic porous minerals have been taken into consideration, which maybe possible and promising templates to prepare carbon adsorbents. In this work, we describe template process using tubular halloysite, rich mesoporous zeolite and low bulk density diatomite, as exemplars of the categories of inorganic porous templates which we have studied and discussed the effects of different templating structure on the resultant carbons. Two main carbon precursors, sucrose and furfuryl alcohol, were used respectively. The morphology of minerals and corresponding templated carbons were characterized using electron microscopy. The pore structures of minerals and templated carbons were characterised with nitrogen adsorption. The results showed that the morphology and pore structure of porous carbons are in good pertinence to those of corresponding templates. The morphology and pore structure of templated carbons could reflect those of corresponding templates at nanometer level. The templated carbons with high specific surface areas and rich mesopores can be prepared by using these three kinds of natural porous minerals as templates. The higher the surface area and pore volume of the minerals, the higher those of the corresponding carbons. The template carbons from halloysite possessed higher pore volume and mesoporosities. Based on the large mounts of experiment results, a model for the mechanism of resultant nanopores formation has been proposed. The nanopores of templated carbons are mainly composed of three kinds of pores: templated pores formed by removing mineral, hereditary pores formed by inheriting the pores of templates and nanopores formed during carbonization. These three kinds of pores have a close relationship with corresponding template.

Jan 1, 2014

By Graeme J. Jameson

"When mineral particles are floated in a mechanical flotation cell, it is found that the rate constant, after reaching a maximum value, starts to decline as particle size increases. It had been thought that the reduction in rate constant had been due to the increased prevalence of composite particles in natural ores, for larger particles. However, Jameson (2012) showed that the rate constant for composites is certainly a function of the surface liberation, but the reduction in flotation rate is independent of particle size. Thus all particles are equally affected by reduced surface liberation, independently of their size. He further argued that the classical peak observed in the rate constant with increasing particle size, is a function of machine hydrodynamics. Thus in mechanical cells, the peak may be due to the high energy dissipation rate and its effects on the detachment of particles from bubbles (Goel and Jameson, 2012). Consequently, in a different flotation environment, it may be possible to float large composite particles that cannot be floated in mechanical cells. This paper describes the flotation of large composite particles in a fluidized bed flotation cell. The particles to be floated are fed to a column in which there is a continuous upflow of liquid. A conventional froth layer of controlled depth is formed at the top of the vessel. A fluidized bed of particles is established which provides a gentle environment for the contacting of large particles with bubbles. An example is given where a porphyry copper ore was prepared at a top size of 710 µm, and floated with conventional collector (PAX) and frother (MIBC). The concentrate was separated into size fractions and examined by photography. Composites were observed at all size fractions, but above 400 µm, all particles were composites. The implications for future flotation circuits will be described."

Jan 1, 2014

By Mingxia Liu, Qi Liu, Tao Jiang

"In addition to physical parameters such as small mass and high specific surface area of fine and ultrafine minerals, chemical parameters such as the adsorption affinity of collectors on the minerals also plays an important role in fine particle flotation. In this study, we have examined collectors with two different ionized groups, carboxylate and hydroxamate, on the flotation of fine niobium oxide (pyrochlore). To facilitate comparison, two hydrocarbon radicals were tested: octyl and oleoyl, which led to four collectors that were studied: octyl hydroxamic acid (OHA), sodium octanoate (C8OONa), oleoyl hydroxamic acid (C18HA), and sodium oleate (NaOl). Small-scale flotation and isothermal microcalorimetric titration measurements were performed to determine the flotation recoveries of different sized pyrochlore and the enthalpic behavior after adsorption of the collectors on pyrochlore. It was found that the flotation performance of the carboxylate-based collectors was generally inferior to hydroxamate-based collectors. Sodium octanoate could not float pyrochlore irrespective of the particle size of the pyrochlore tested. With a longer hydrocarbon chain, sodium oleate was effective to float the relatively coarse pyrochlore (>20 µm) but its collection efficiency dropped sharply for particles smaller than 20 µm. On the other hand, the two hydroxamate-based collectors, octyl hydroxamic acid and oleoyl hydroxamic acid, showed good collecting ability to both the coarse and fine pyrochlore. The isothermal microcalorimetric titration studies indicated a consistent correlation of chain length with floatability of collectors for relatively coarse pyrochlore, as well as a positive relationship between the adsorption affinity and fine pyrochlore flotation recoveries. The key finding of this study was that efficient fine particle flotation could be achieved when strongly chemisorbing collectors were used.INTRODUCTION The first detailed study of the effect of particle size on flotation was made by Gaudin (1931) with sulphide ores. In 1942, Gaudin again demonstrated that (Gaudin et al., 1942) fine particles possess different flotation properties from larger particles. Since then the effect of particle size on froth flotation has been an important research topic by many researchers, e.g., Gaudin (1957), Miettinen et al. (2010), Warren (1976) Jameson (2010), summarizing the behavior of fine particles in terms of their low particle momentum, leading to low rate of collision with bubbles which reduces the chance of adhesion. The suggested remediation methods are mainly based on two approaches: increasing particle size or decreasing bubble size (Warren, 1976). Sand-fine splitting followed by separate flotation treatment of the sand and fines, using deep flotation cells, using starvation quantities of collectors, and using long flotation times, are also strategies to address the problems of fine particle flotation."

Jan 1, 2018

By Johannes Käppeler, Alexander Weh, Harald Giese, Klaas van der Wielen

"High voltage breakage is a novel comminution technology that shows considerable potential for various applications in mineral processing and recycling. It relies on highly energetic electrical pulses to induce electrical explosions in rocks, causing the formation of plasma channels and powerful shockwaves that result in fracturing and fragmentation of particles. There has been considerable interest in this technology for its ability to weaken rocks and preferentially liberate target minerals, as previously demonstrated by other authors. Weakening has the potential to significantly reduce energy consumption during comminution, or alternatively, increase throughput of a circuit. Better liberation may yield an improved concentrate grade and/or recovery, reduce fines losses to tailings or increase the grind size required for liberation, thereby also reducing energy requirements. This review aims to increase general awareness of this technology, and promote further research into it by providing a general summary of the theory underlying high voltage breakage, as well as the envisaged applications of this novel technology. A brief history of the technology is presented before progressing onto the physics underlying the electrical and geomechanical aspects of high voltage breakage. Key results regarding weakening and liberation are discussed, and some mention is made of current challenges and planned developments to increase the throughput of high voltage breakage units to the level where it can be integrated into new and existing processing circuits."

Jan 1, 2014

By A. Kuriwada

Dolomite is a mineral, which consists of CaCO3 and MgCO3. In this work, a series of experiments were carried out in order to adsorb boron from a boron-containing solution using a calcinated dolomite sample, and then to desorb it from the loaded adsorbent. A particular modification on the surface of dolomite was observed when it was thermally treated at certain temperature, ranging from 750 oC to 1050 oC; in turn, it is the specific surface was increased. In other words, the experimental results suggested that the calcinated dolomite exhibited a high adsorption capacity for boron, indicating its effectiveness in effectively adsorbing boron from drinking water or wastewater.

Sep 1, 2012

By V. Panayotov

Flotation practice usually uses the Sheridan-Grizvold selection method, where zinc minerals are activated by addition of copper sulphate and depressed by addition of sodium cyanide, ferrous sulphate, zinc sulphate or various mixtures of these reagents. The method is suitable for the flotation of sulphide ores, which, do not bear precious metals, such as silver and gold. When classical technology with cyanide is applied to depress zinc minerals, the precious metals, which are contained mainly into lead minerals, are dissolved into the solution, which represents a technological loss. In order to avoid this process, we have made use from the knowledge on the semiconducting properties of lead and zinc sulphide minerals. We have changed the surface charge of minerals by means of an electrochemical impact realized by direct current application and specially designed set of insoluble or semi-soluble electrodes. Thus, flotation separation of lead and zinc sulphide minerals was achieved, at increased recovery of lead, zinc and silver. The technology proposed was implemented in a Bulgarian flotation factory; it worked over 5 years providing significant, positive economic, technological and environmental impact. Silver recovery was increased by 0.8-1.0 %, and lead and zinc recovery was increased by 0.8-1.0 %. The technology is easily controllable and adaptable to raw materials and parameters of the technological process. It can be paid back for 6-8 months after the implementation. Keywords: lead-zinc flotation separation, electrochemical impact

Sep 1, 2012

By Takaaki Wajima

The slag was attempted to be converted into the adsorbent for phosphate removal from aqueous solution using the alkali fusion method. The slag was mixed with NaOH powder (NaOH / Slag = 1.6), and then the mixture was heated at 600 ? for 6 h to prepare the precursor. The precursor was stirred at room temperature in distilled water to synthesize the adsorbent, and the removal ability of the obtained adsorbent for phosphate from aqueous solution was investigated. The products, including hydrocalumite and calcite, were synthesized, and the removal efficiencies of the adsorbent for F- and PO43- showed higher than those of raw BF slag, especially removal of PO43- are excellent (99 %), while the removal of Cl- , SO42-, NO3- and Br- was minor. The adsorbent could remove PO43- selectively in the co-existing solution of Cl-, NO3-, F-, SO42- and Br-.The equilibrium adsorption capacity of the adsorbent for PO43- was extrapolated using Langmuir and Freundlich models, and experimental data are found to fit Langmuir than Freundlich. The calculated maximum adsorption capacity of the adsorbent for PO43- is higher than other adsorbent reported previously. The high affinity of the adsorbent for PO43- in aqueous solution was caused by the formation of hydroxyapatite [Ca5(PO4)3(OH)] and brushite [CaHPO4?2H2O]. The prepared adsorbent is expected to be anew inorganic adsorbent for the removal of phosphate ion from wastewater. Keywords: Blast furnace slag, Alkali fusion, Phosphate removal, High selectivity

Sep 1, 2012

By Masoud Askari, Ahmad Rafizadeh, Shahamat Rostami, Mohammad Qaredaqi

Gole - Gohar Iron ore mines located in Sirjan, Southeast of Iran, have more than 1 billion Iron ore deposit and this area comprises 45 % of Iran Iron reservoirs. The aim of Wet tailing processing line is recovering Hematite ore from wet tailing of Gole - Gohar iron ore processing plant. The Investigations of Hematite recovery plant showed that the recovery of Iron ore to concentrate in Wet Tailing Processing (WTP) line is very lower than that has been predicted, sampling, and designing of the process parameters are not accurate and designed magnetic field intensity is not reasonable for the recovery of Iron in form of Hematite in this line feed. Applying of MIMS in WTP separator and changes in circuit caused in overwhelming increase of Fe recovery, from 11 to 40%. Although recovery of WTP line was improved, but low recovery of this processing line and high content of Hematite ore in WTP tailing, made applying Wet High Intensity Magnetic separators unavoidable. Two kinds of WHIMS have tested for processing of WTP line tailing. Results showed that traditional Jones separator with grooved plate matrix, is more suitable to achieve a better quality of concentrate compared to Slon® separator.

Jan 1, 2014