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By E. Guerrini, M. Maccagni, J. Nielsen

"The solution for the treatment of the EAFD has not yet been fully achieved. Some of this dust has still not found an appropriate final destination. Large consortium treatment plants are quite expensive both in terms of investment and operating cost. Meanwhile, the tolling expenses for steel production companies are becoming very important, causing them to look for alternatives. Some steel plants are looking to close their production loop by internal treatment of their dust. Some years ago, Engitec began studying the coupling of the EZINEX® Process, an ammonium chloride electrolysis to recover the zinc contained in the EAFD, with the INDUTEC® Process, a pyro process based on an induction furnace that can convert EAFD into a C.Z.O. similar to the Waelz oxide. The combination of these two processes provides an alternative to the existing treatment options and is particularly interesting for relatively small capacities. In this paper, we would like to give the latest update about these two processes and their possible integration INTRODUCTION Zinc is contained in numerous wastes and secondary raw materials that can be thought of as high zinc concentrate mines. This is a very interesting source of Zn that is typically easily exploitable. Unfortunately, only a portion of these materials are currently processed to recover the metal value, while stabilized or unstabilized landfilling is often the final destination. Pyrometallurgical processes are mainly used to convert the zinc into crude zinc oxide (CZO). The various processes are very similar and characterized by the fact that the zinc bearing materials are usually submitted to a thermal treatment [1] in which the zinc is reduced, vaporized and re-oxidized producing CZO. This material not only contains zinc oxide, but also relatively high concentrations of heavy metals. Many potential CZO sources, such as electric arc furnace dust (EAF), galvanizing ashes, brass foundry and converters fumes also contain chlorides, fluorides and alkali metals that will transfer to the CZO. The classic example is the Waelz oxide [2]. This CZO is an intermediate product that must be transformed into zinc salts or zinc metal. Until now, the conversion to zinc metal is done through two main processes: the sulphate leaching and electrowinning system and the Imperial Smelting Process (ISP). ISP is facing a crisis for technical and economic reasons that has led to the closing of most of the existing plants. In any case, before being fed to one of these two processes, the CZO must be treated to eliminate or reduce some of the contained impurities. In particular, the halides are most harmful to these processes."

Jan 1, 2018

By E. Guerrini, M. Maccagni, J. Nielsen

"The solution for the treatment of the EAFD has not yet been fully achieved. Some of this dust has still not found an appropriate final destination. Large consortium treatment plants are quite expensive both in terms of investment and operating cost. Meanwhile, the tolling expenses for steel production companies are becoming very important, causing them to look for alternatives. Some steel plants are looking to close their production loop by internal treatment of their dust. Some years ago, Engitec began studying the coupling of the EZINEX® Process, an ammonium chloride electrolysis to recover the zinc contained in the EAFD, with the INDUTEC® Process, a pyro process based on an induction furnace that can convert EAFD into a C.Z.O. similar to the Waelz oxide. The combination of these two processes provides an alternative to the existing treatment options and is particularly interesting for relatively small capacities. In this paper, we would like to give the latest update about these two processes and their possible integration INTRODUCTION Zinc is contained in numerous wastes and secondary raw materials that can be thought of as high zinc concentrate mines. This is a very interesting source of Zn that is typically easily exploitable. Unfortunately, only a portion of these materials are currently processed to recover the metal value, while stabilized or unstabilized landfilling is often the final destination. Pyrometallurgical processes are mainly used to convert the zinc into crude zinc oxide (CZO). The various processes are very similar and characterized by the fact that the zinc bearing materials are usually submitted to a thermal treatment [1] in which the zinc is reduced, vaporized and re-oxidized producing CZO. This material not only contains zinc oxide, but also relatively high concentrations of heavy metals. Many potential CZO sources, such as electric arc furnace dust (EAF), galvanizing ashes, brass foundry and converters fumes also contain chlorides, fluorides and alkali metals that will transfer to the CZO. The classic example is the Waelz oxide [2]. This CZO is an intermediate product that must be transformed into zinc salts or zinc metal. Until now, the conversion to zinc metal is done through two main processes: the sulphate leaching and electrowinning system and the Imperial Smelting Process (ISP). ISP is facing a crisis for technical and economic reasons that has led to the closing of most of the existing plants. In any case, before being fed to one of these two processes, the CZO must be treated to eliminate or reduce some of the contained impurities. In particular, the halides are most harmful to these processes."

Jan 1, 2018

By A. Muhammad, A. Abdelaal, M. EL Salmawy

"Energy is vital for economic growth and sustainable development. Greater efforts are being devoted to developing unconventional energy resources such as oil shale as an alternative promising source of oil or solid fuel supplement. The main object of this contribution is to determine the upgrade potential of El-Nakheil oil shale using froth flotation. Samples were prepared by comminution followed by sieving into different size fractions. The flotation behavior of the material and extent of cleaning was studied with respect to nonionic and ionic collectors of anionic and cationic types. It was found that the organic rich portions could not be rendered sufficiently hydrophobic by the used collectors and selectivity towards surfactant was very low."

Jan 1, 2014

By M. Rudolph, E. Schach, M. Buchmann, T. Leißner, N. Krupko, U. Peuker, M. Kern

"In mineral processing, density and magnetic susceptibility are two very fundamental properties. For the beneficiation of valuables to produce a saleable concentrate a detailed understanding of these properties is essential. Especially when it comes to the processing of cassiterite, which is the main mineral for tin production, they become highly prominent. Due to the chemically inert character of cassiterite towards most industrial applied leaching agents, density and magnetic separation processes are mainly applied for its beneficiation. To guarantee an optimized utilization of the different operations not only cassiterite but also the different gangue minerals have to be considered. In this study, a skarn ore is characterized by density and magnetic susceptibility. Therefore, the material was first split into different density classes by heavy liquid separation. The obtained classes were further separated by their susceptibility to finally obtain a density-susceptibility matrix. For this purpose, an isodynamic separator was used. A more detailed characterization of the materials is done via gas pycnometer, magnetic susceptibility balance and vibrating sample magnetometer to estimate the characteristics of density and susceptibility for the various classes. Further, the determination of the chemical assay and the mineral intergrowth by mineral liberation analysis is used to generate a three dimensional database for detailed characterization of the present ore. The objective of this study is to estimate potential material streams for a modular processing plant via characterization of the material for the entire deposit by the two afore mentioned characteristic properties. The established multidimensional data matrix, enables predictions for the separation properties of the material and contributes to the characterization of the deposit within the context of geometallurgy."

Jan 1, 2018

By D. W. Feng

Thiosulfate leaching has been considered as the most promising alternative to cyanidation for the recovery of gold from ores. The chemistry of the ammonia-thiosulfate-copper system is complicated due to the simultaneous presence of complexing ligands such as ammonia and thiosulfate, the Cu(II)-CU(I) redox couple and the stability of thiosulfate in solution. However, acceptable gold leaching rates can be achieved by maintaining suitable concentrations of thiosulfate, ammonia, cop-per and oxygen in the leach solution. The leaching of gold in thiosulfate solution is an electrochemical reaction involving the oxidation of gold to gold thiosulfate and the reduction of Cu(II) to Cu(I). Previous studies have shown that the reaction rate of gold was much higher in the presence of am-monia thiosulfate than corresponding sodium thiosulfate. This indicates that cations may affect the anodic oxidation of gold in thiosulfate solution. The present study utilises electrochemical tech-niques to study the anodic oxidation of gold in thiosulfate medium in the presence of the different alkali metal and alkaline earth metal ions. It has been shown that the presence of the heavier cations such as potassium, calcium, and caesium enhance the oxidation of gold in thiosulfate solution. Leaching tests also indicated the improved recovery of gold from a sulfide ore with the addition of heavier cations. XPS results demonstrated that the binding energy for gold shifted to lower values in the presence of the heavier cations, indicating the ready formation of ion-pair with gold thiosulfate at the gold surface during adsorption.

Jan 1, 2014

By S. V. Petrov

In recent years, heap leaching of gold is becoming wide spread due to low capital and operational costs that allows economically feasible processing of low-grade and cut-off grade ores. Currently, over 30 heap leach projects are operated in Russia. Some of the deposits treated by heap leach methods are almost depleted. Therefore, they will soon require spent heaps detoxification and reclamation. Traditionally, spent heaps are detoxified by chemical treatment. This process is characterized by relatively high kinetics and requires expensive reagents and additional equipment. The main disadvantage of this process is secondary contamination of the solutions by products of detoxification reactions and impurities contained in reagents. If there is enough time, spent heaps can be detoxified by natural degradation. The advantages of the proposed method are low operational costs due to use of existing heap leaching facilities and eliminating the need for chemicals for spent heaps detoxification. Residual concentrations of cyanides and thyocyanates in liquid phase (wet ore) of spent gold ore heaps after detoxification were 0.2~0.3 mg/L. Heavy metals were almost completely removed. The method was successfully used for detoxification of spent heaps at two gold mines.

Jan 1, 2014

By Smuts. E. M.

This paper describes a methodology used to develop a numerical model for the study of particulate suspension rheology. Initially, Computational Fluid Dynamics (CFD) models of different rheometer geometries were tested with both a Newtonian fluid (water), and a non-Newtonian Herschel-Bulkley slurry. Rheograms were reproduced from these models and compared to experimental values. Once a single-phase model had been validated, a coupled model combining CFD and the Discrete Element Method (DEM) was created. Two open source software packages were chosen. CFD is implemented using Open FOAM®, and DEM using LIGGGHTS. These two different codes were coupled via another program called CFDEM. This coupled model is currently capable of modeling spherical particles in a suspending liquid. DLVO forces have been included in some models to account for inter-particle forces due to the surface charge on the particles. The coupled model is currently being validated. Preliminary results show good qualitative behavior of the model. Keywords: rheology, cfd, dem, suspensions, modeling

Sep 1, 2012

By Magnus Evertsson, Haijie Li, Erik Hulthen, Mats Lindqvist

"The static and dynamic models for autogenous (AG) and semi-autogenous (SAG) mills have been studied for decades. Though the effects of mixing soft and hard ores in a mill and their interactions are not widely investigated. To develop a general numerical model for AG/SAG mills, a dynamic model has been introduced, and its capability to simulate multi component ore breakage has been examined and compared with previous publications. The simulation results show that the dynamic model can cover a range of milling conditions and is able to simulate complex scenarios with soft and hard ores. The dynamic model discussed here could provide substantial potential for the controlling and optimization of the comminution circuits. INTRODUCTION In the last decades, efforts have been devoted to studying the comminution circuit due to their high energy consumption. The energy directly spent in minerals comminution was about 2% globally in the year 2000 (Maurice et al, 2003). As one important part of the comminution process, AG/SAG mills are widely used for primary grinding in minerals processing. AG/SAG mill models include static and dynamic models (Kojovic et al, 2012; Yu et al, 2014; Yu et al, 2017; Liu and Spencer, 2004; Salazar et al, 2009). Many static models have been well validated over the past decades, but they are all based on steady state assumptions. Even though plants experience a steady-state condition under certain circumstances, it can be inaccurate to simulate the system by static models under all circumstances (Asbjörnsson et al, 2013). The advantages of a dynamic model are apparent that it provides more information and insights both inside the mill and through interactions with other machines in terms of pebble crushers, conveyor belts, screens and so on. In many mines, the multi-component grinding is inevitable, and the ratio of hard and soft components in the mill strongly affects mills operation and performance. Bueno (Bueno et al, 2010; Bueno et al, 2013) studied the effects of blending hard and soft ores in AG/SAG mills and used them to update the JKSimMet toolkit which was a steady state plant simulation software. However, due to the complexity of the particle interactions such as multi-component breakage function, appearance function, in mill transportation, there has been no dynamic AG/SAG mill models developed yet for simulating multi-component."

Jan 1, 2018

By R. L. Pascual, W. J. Whiten

"The froth flotation process is not well understood. Both flotation models, and the parameters used to describe the stream flows are not well defined. They in fact vary considerably in different applications. This creates difficulties is designing a simulation program suitable for use by plant personnel, consultants, and researchers. In addition to simulation, an effective simulation program can be expected to provide a range of other services.This paper shows how a process circuit simulator can be designed with sufficient flexibility to satisfy these needs, and discusses some of the additional services."

Jan 1, 2003

By Xuliang Yang, Yuemin Zhao, Bo Zhang, Liang Dong, Cheng Sheng, Gongmin Li, Zhenfu Luo, Yaqun He, Chenlong Duan

Coal plays an important role in the primary energy consumption of all over the world. In 2012, coal reached the highest share (29.9%) of global primary energy consumption since 1970. Coal burning mainly contributes to the emission of SO2, NOX, Hg and other impurities that jeopardize the future of environment. . Beneficiation before coal utilization is the most economical and effective technology for removing the hazardous material and gangue. In this paper, a novel process of dry beneficiation based on gas-solid two-phase flow composed of the compound dry cleaning separator (FGX), the air dense medium fluidized bed separator (ADMFB) and the vibrated fluidized bed with autogenous medium (VFB) is proposed. The main equipment and the flowsheet of the united system are described in detail. Separating principle of the FGX, ADMFB and VFB devices are all based on gas-solid two-phase flow. In FGX, gassolid suspension is composed of continuous gas flow and coal powder in feed coal. Large size coal (+6- 80mm) can be pre-separated effectively, and large size gangue can be removed effectively. Moreover, - 6mm particles fed serve as autogenous medium in FGX. The probable E value is 0.13 for -80 mm raw coal. In ADMFB, magnetic powder with -0.3 + 0.045 mm size fraction and coal powder in feed coal are compound medium solids. The separation density can be adjusted and controlled according to properties of raw coal. -50 + 6 mm raw coal can be cleaned efficiently, the probable E value is 0.05. In VFB, -6 + 1 mm coal can be separated. Generally, -80 mm raw coal can be cleaned efficiently in the united system based on gas-solid two-phase flow.

Jan 1, 2014

By J. Lampke

The superior characteristics of iron ore pellets compared with natural ore and sinter are well known. Due to the higher grade and bulk density they show improved transport and material handling properties. While charging blast furnaces with pellets an increased productivity is realized through pellet?s uniform structure and composition. The increased productivity is caused by a high permeable furnace burden with a decreased coke usage via fuel injection and oxygen enrichment. Therefore, a narrow pellet size distribution and a minimum content -6.3 mm are necessary (Meyer, 1980). The required pellet size distribution can be achieved on the one hand by screening the fired pellets after the induration furnace and recycle the undersized pellets. On the other hand it is possible to produce high quality iron ore pellets with a high degree of sphericity, the important narrow grain size distribution ranging between 9 to 16 mm with high green strength directly in the pelletizing device. To produce high quality green pellets, possibilities and knowledge about adjustments of the pelletizing device are necessary. The paper presents a classification of state of the art pelletizing systems in accordance with the advantages of the pelletizing disc and pelletizing drum in issues like adjustability, green pellet quality, the recycling rate and the space requirement. By a systematization of the influences on pelletizing the common reliance of objectives on influence like pelletizing moisture, disc inclination, rotational speed, mass flow and rim height are given. A variety of industry-proven examples are shown, too. Keywords: Pellet, iron ore, pelletizing, pelletizing disc

Sep 1, 2012

By N. Naudé

The theory on particles displacement subjected to upwards and settling movements in water, using a water pulse, is described in literature, but very little experimental data is available to verify these theoretical ideas. The aim of this research work was to visualize the displacement of solid particles in a mixture of water and solid particles created with the aid of water pulses in the Mineral Density Separator. From the literature it is known that lighter particles are subjected to higher levels of displacement than heavier particles, and when the particles then settled down, layers of material are formed ac-cording to the densities of the material. By removing the individual material layers, the materials can then be separated according to their densities. During this study the individual material layers were investigated regarding the density and size distribution in that specific density layer. It is important for this project to have a statistical prediction of the ?real? flow of the particles with different density and size distribution, inside the Mineral Density Separator. The information gathered during this study will be used to show the correlation between a two dimensional model of the particle flow and that of the real three dimensional flow inside the Mineral Density Separator.

Jan 1, 2014

By R. Singh

The paper presents the results of characterization and beneficiation studies carried out on a lean grade tungsten ore sample from Degana, India. Basically, three different routes, involving gravity separation, magnetic separation, and froth flotation were studied for concentration of the sample by physical and physico-chemical methods. Considering the low recovery by physical methods, efforts were put in to produce a tungsten concentrate by physical methods suitable for subsequent hydrometallurgical recovery of tungsten as ammonium para-tungstate. This strategy proved quite helpful in minimizing the losses of tungsten in tailings. Based upon these studies a novel integrated technological process flow-sheet was developed for the exploitation of lean grade tungsten ore deposit of Degana, India. Keywords: lean tungsten ore, characterization, beneficiation, gravity and magnetic separation, hydrometallurgical extraction, integrated process route

Sep 1, 2012

By F. Concha

A robust theory of sedimentation-consolidation evolved and was accepted by researchers world-wide in the last two decades of the 20th century. This theory provides a reliable method of thickener design and simulation. However, a process model, simple or sophisticated, empirical or phenomenological, is useful only if it is possible to determine, in an objective way, its experimental parameters. Research workers at the University of Concepción, together with Cettem Mineral Technology Center, created an integrated system of thickener design, simulation and control, including instrumentation, algorithm and software, which can be used by personnel in industry without specialized knowledge of thickening theory. In the paper, the development of three instruments for the measurement of pulp concentration, solid flux density and sediment compressibility is described. Each instrument uses software for data input, parameter calculation and results display. The paper also describes software for the optimization of the experimental parameter and for the design and simulation of industrial thickeners. Finally, mathematical algorithm and control strategies based on the phenomenological model are presented and compared with classical feedback control.

Jan 1, 2014

By Klaus M. Hahn, Hermann Wotruba, Bernd G. Friedrich

"Due to an increasing demand for nickel and cobalt and the depletion of nickel sulphide deposits worldwide, the production of ferronickel from lateritic nickel ores becomes more significant. About 60 percent of nickel reserves are present in laterite deposits. Common production methods like acid leaching or smelting operations implicate high material and energy consumption. Physical processing methods are also not efficient, because of the fine microstructural intergrowth of the minerals carrying valuable elements such as nickel and cobalt. Due to the high energy consumption of metallurgical treatment of lateritic nickel ore (nickel grade: 0.8 - 3.0%, Co: 0.05 - 0.15%), the separation of waste material (about 75 - 85%) before the metallurgical treatment is desirable. Therefore, an alternative process has been developed, combining a pyro-metallurgical pre-treatment with selected mechanical processing methods. The developed process consisted of a selective pre-reduction and non-selective segregation of the contained metal phases in the first stage. By this, the properties of the metal carrying minerals were changed and could become subject to concentration by means of fine beneficiation processes afterwards. The parameters of the pre-reduction and segregation were varied and the pre-treated samples were examined concerning their efficiency of metalization grade and metal grain size. This paper describes the investigation of pre-treatment methods of a lateritic nickel ore. The pre-treatment and possible subsequent separation methods were examined with regard to the recovery of the valuable elements. Metalization grade was around 80% for both Ni and Co with metal phase grain sizes below 20 µm. Scanning electron microscopy revealed distribution of new metal phases not only on the reducing agent, but also on the “slag” material.INTRODUCTION Nickel laterites are characterized as strongly weathered regoliths with several zones containing reserves of nickel (Ni) and cobalt (Co). These laterites are formed on serpentinites and ultramafic rocks under climatic and/or tectonic conditions that have changed over time (Butt & Cluzel, 2013). The formation of Ni laterites is influenced by numerous geological and environmental factors. In general, there are three ore types named according to the dominant Ni hosting minerals: oxides, hydrous magnesia (Mg) silicates and clay silicates (Butt & Cluzel, 2013). The most Ni laterite deposits contain two of these ore types, usually an oxide zone and an either clay or Mg silicate zone. Distribution of these principal deposit types, their average Ni-bearing phases and mean Ni grade are shown in Table 1. A schematic profile of the different deposits based on the development on serpentized ultramafic rocks is given in Figure 1 (Butt & Cluzel, 2013)."

Jan 1, 2018

By Deirdre Bradshaw, Cornelius Vos

"The detailed understanding of the variability in process performance parameters within an ore body forms a key aspect of ensuring that proper decisions are made with regards to the economic viability of that ore body. To gain this understanding, various tools have been developed over the years, of which the batch flotation test is the most well-known and applied technique for investigating the flotation separation of ores. In this paper, the Julius Kruttschnitt Mineral Separability Indicator (JKMSI) is put forward as a small-scale test, suitable for the characterization of the flotation separability of copper porphyry ores. It is demonstrated that the JKMSI can be a complementary technique to the batch flotation test, with the capability to further improve the knowledge of ore body variability. The response from this test has been shown to be sensitive to particle size and modal mineralogy, providing a critical link between flotation and upstream comminution activities. The trade-off between the fineness of grind and the recovery target can thus be evaluated to determine the minimum energy application required for optimal separation economics. The test is designed to utilize small sample quantities of various sizes, providing an opportunity to increase our understanding of ore variability through increased tests. This complements our ore body knowledge and combining this with efforts in comminution (Powell, 2013) provides a platform for extending the concept of flexible circuit design."

Jan 1, 2014

By T. Sun, J. Kou, C. Sun, D. Gong

"HPGRs (high pressure grinding rollers) have demonstrated higher energy efficiency than conventional comminution equipment due to their application of particle-bed breakage mechanism. In the past decades, a large number of studies have been conducted to understand the characteristics of particle-bed breakage, however, few of them concerned the difference between single-particle and particle-bed breakage in compression comminution. This comparison is able to demonstrate possible advantages of particle-bed against single-particle in a breakage event due to the isolation of the effect of force loading mechanism. The present study investigated progeny fragment size and energy efficiency of these two breakage methods at variable energy inputs and particle sizes. The results show that at low energy inputs of around 0.25 kWh/t, the numbers of fines resulting from the two breakage methods are very similar. However, at higher energy inputs of around 1.0 or 2.0 kWh/t, particle-bed breakage generated significantly more fines. From the perspective of newly generated surface energy, particle-bed breakage is obviously more energy efficient than single-particle breakage at energy inputs between 1.0 and 2.0 kWh/t. It was also found that HPGRs demonstrate high energy utilization rate in generating new surface energy within their typical range of specific energy input. INTRODUCTION Rock comminution is an important and energy-intensive process in mining operations. Nowadays, decreasing head grade and mineral liberation size of ore deposits greatly increase the energy cost of comminution process. HPGRs have been successfully applied in the mining industry to improve the energy performance of comminution circuits. Typically, 10 to 30% of energy saving can be achieved due to the application of HPGR (Wang et al., 2013; Casteel, 2005; Günter et al., 1996)."

Jan 1, 2018

By I. A. S. Brum

Brazil has large reserves of coal (7 billion tons) located predominantly in the south of the country. Despite the relative ease of exploitation, these resources have been underestimated as a source of energy. Currently the country's strategic planning aims to minimize the gap between coal and resources traditionally used in the Brazilian energy matrix. In this scenario, the processing of Brazilian coal in columns flotation appears as a promising alternative, having been successful in mineral systems containing fine particles. This paper aims to study the overall process of column flotation for a specific Brazilian coal. The material used in this study consists of fine coal that is usually discarded as waste and deposited in the tailings dams. The objective is to recover carbonaceous matter and reduce the ash and contaminants grade. The variables analyzed were the influence of size particle, solids concentration in the pulp, the concentration of surfactants and frothers to be used. The first results showed that it is possible, from a feed with around 65% of ashes, to obtain products with approximately 35% ashes with mass recoveries about 40%. Concentrations of frother (pine oil) ranged from 50 g/t to 300 g/t and the collector (diesel oil) of 50 g/t to 200 g/t. Keywords: column flotation, coal, tailings, negative bias

Sep 1, 2012

By M. Abdollahy

In this paper, the hydrophobicity of chalcopyrite particles produced with different laboratory mills has been studied; different grinding mechanism in themills made some changes in particles shape, Image Analysis (IA) method was used to determine the shape properties of chalcopyrite particles which are ground by a laboratory ball mill, rod mill and ceramic ball mill. The shape characters are stated in terms of shape factors such as circularity, convexity, roundness and regularity factor. Hallimond tube was used to float chalcopyrite particles followed by determination of critical surface tension of particles, this parameter used as a criterion to study the wetting behavior of chalcopyrite particles. The correlation between shape properties and critical surface tension of chalcopyrite particles showed that the hydrophobicity of chalcopyrite was affected by the shape. Investigations showed that the circular, round and more convex particles that produced with ceramic ball mill had lower hydrophobicity with higher critical surface tension (?c). The results also showed that the hydrophobicity of particles ground by ball and rod mills increased with the decrease of roundness, circularity, convexity and regularity factor of particles. Keywords: chalcopyrite, particle morphology, flotation, image analysis system, micro flotation method, hydrophobicity, shape properties

Sep 1, 2012

By N. Karapinar

Ferrihydrite, a member of iron oxides family, has been used as an adsorbent for the removal of heavy metal ions from industrial wastewater. The success of the operation depends mainly on the efficient removal of ferrihydrite from the aqueous phase. Hence, the emphasis of this study was given on the separation of ferrihydrite by high gradient magnetic separation (HGMS) method to overcome solid-liquid separation difficulties of ferrihydrite. Magnetic seeding technique in which the magnetite mineral was chosen as a seeding reagent was used to make magnetic separation available. The method clearly involves the attachment of ferrihydrite to a magnetic seed material and subsequent magnetic separation of ferrihydrite ? magnetite coagulates. Seeding of ferrihydrite with magnetic particles was achieved by exceeding the solubility limit of the ions in the presence of dispersed magnetite. Magnetic separation results of seeded ferrihydrite showed that maximum seeding performance is obtained in the pH range of 7.0~10.0. Iron/magnetite ratio had a marked effect on the separation of seeded iron oxide precipitate by HGMS. This ratio determines the operation parameters such as magnetic field strength and flow rate. It was concluded that when used with magnetic seeding technique, HGMS can be used to surpass separation difficulties of ferrihydrite used in adsorption-based treatment techniques.

Jan 1, 2014