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By Mao Chen, Baojun Zhao, Zhixiang Cui, Leonel Contreras

Viscosity is one of the important physiochemical properties of metallurgical slags which is important for slag tapping, metal loss in slag, freeze lining and fluid dynamics. High temperature viscosity measurements are time- and cost-consuming and the number of experiments is limited. Viscosity model is an effective way to predict the viscosities of the complex slags at high temperature. However, a reliable viscosity model can only be developed on the base of accurate experimental data. A unique high-temperature viscosity measurement apparatus developed at The University of Queensland enabled accurate viscosity data to be measured for the “FeO”-SiO2-CaO-MgO-Al2O3 system in equilibrium with Fe. An accurate viscosity model has been developed based on Eyring’s theory and extensive viscosity measurements. The viscosities of copper smelting, converting and cleaning slags over a wide range of compositions and temperatures can be predicted and applied in the process control.

Jan 1, 2016

By Susanne Pignolet-Brandom

Reflected light microscopy scanning electron microscope energy dispersive spectroscopic analysis and backscatter electron image and electron microprobe chemical analysis have been used to study lead sinter and lead blast furnace slag. These studies provide invaluable information on the phases present their intergrowths, and their chemical composition. Such information increases the understanding of the nature of pyrometallurgical processes and the behavior of minor elements during these metallurgical processes.

Jan 1, 1987

By B. W. Lightfoot, Neill F. Arthur

"The AusIron process is a new development of the well established Ausmelt bath smelting technology(l). The development of this technology has been tied to the South Australian Steel and Energy (SASE) project which brings dedicated coal and iron resources together with this new technology. SASE is a joint venture between Ausmelt (40%), Meekathara Minerals (40%) and the South Australian Government through Mines and Energy South Australia (MESA) (20%). It will use a multiple lance furnace to process iron ore using steaming coal for both fuel and reductant.It is intended to build the simplest plant economically possible. Refinements such as preheating and prereduction of the ore are compatible with the technology but are not expected to be necessary in the first generation plant.The joint venture is negotiating with suitable partners for funding of the project through to commercial implementation at a target scale of2.5 mt/a of pig iron.ObjectivesAusIron aims to produce pig iron directly from steaming coal and from any of a variety of iron sources in a simple furnace system with a minimum of pre-processing of either coal or iron ore. Preheating and prereduction of ore are compatible with the technology but may not be necessary. The immediate aim is not to be the technology that uses the least quantity of coal to produce iron metal but rather the technology that uses the least number of dollars to produce metal.The chemistry of iron making is well known, probably better known than that of smelting of any other metal. Iron has been made for thousands of years and it is possible to make iron from charcoal and ore in a simple blast furnace the size of a beer barrel. The focus is therefore not making iron but rather making it more cheaply than it is made by current technologies. Large blast furnaces now set the standard and new technologies must perform better if they are to gain market share. It is still the cost of iron, energy units and capital going into these mega blast furnaces which ultimately set the market price for pig iron."

Jan 1, 1996

By O. Ryosuke Suzuki

A new metallurgical process via sulfide is proposed: a sulfide is produced at a high temperature from its metallic oxide using gaseous CS2, and this sulfide is electrochemically reduced to its metallic state using molten salt. This combined process via sulfide is effective to obtain high purity of metallic powder, even if the metal in its oxide is strongly combined with oxygen. For example, it is not easy to reduce stable oxide TiO2, and only Ca can remove oxygen to form α-Ti. However, a fairly large amount of oxygen remains as Ti–O solid solution. Because the solubility of S in Ti is very small, this proposal was examined experimentally both on the conversion of TiO2 to TiS2 and on the successive reduction of TiS2 to Ti. TiO2 powder was exposed to CS2 gas flow at 1073 K, and the conversion to TiS2 was confirmed. TiS2 could be reduced to Ti powder either by calciothermic reduction or electrolysis in a CaCl2 melt. By Ca reduction at 1133 K in CaCl2 melt, sulfur concentration decreased to 0.03 mass%S when the amount greater than twice the stoichiometric calcium amount is added. By electrochemical reduction at 1173 K in CaCl2–CaS melt, S concentration significantly decreased to 0.01 mass% S when four times larger amount of electric charge was supplied.

By T. Shimizu

In Japan, the emission standard of selenium in effluent was set at a maximum of20 mgll in Feb. '94 for the first time, and it is scheduled to be further decreased to a maximum of 0.1 mg/I from Feb. '97 due to tightening of the Water Pollution Prevention Act. Selenium (IV) and (VI) are generally found in effluent from precious metals refineries. Although selenium (IV) can be easily eliminated by some reducing agents, selenium (VI) is more difficult to be reduced. Therefore, many smelters are having difficulty in complying with the new emission standard. At Mitsubishi Materials' Naoshima smelter, the behavior and the elimination of selenium in effluent have been extensively investigated. As a result, it was found that two strategies were particularly effective. One of them is improving the overall operation of precious metals refinery, that is, feeding uniformly the effluent to the waste-water treatment plant, reducing the effluent volume by recycling and recovering more selenium (IV) in the effluent. The other is eliminating selenium (VI) in the effluent from the precious metals refinery. It was found that selenium (VI) can be effectively reduced by using hydrazine under high? sulphuric acid concentration and high temperature conditions. By using these measures, it is considered that Naoshima Smelter will be able to comply with the new emission standard.

Jan 1, 1996

By Andre Krzysik

"Fluidized bed technology has been used in the industry for almost 100 years. To fully understand the process hundreds if not thousands of researchers were and are involved in finding the way to predict the behavior of the solids when subjected to the flow of media through them and the conditions of the solids in the fluidized state. The difficulties in predicting the behavior of solids in the fluidized state stem from the complexity and abnormality of the parameters related to the solid particles. Theoretical calculations can in some degree account for some of them. Particle size distribution, their shape, density, moisture content and physical and chemical reaction that may exist in the fluidized bed reactor play an extremely important role and influence the behavior of the fluidized bed. This paper focuses on the practical examples of the fluid bed equipment and the use of different conditions to process various products.IntroductionEach process application has its own unique requirements and the designers of the equipment must take into consideration specific process requirements, specific properties of the material to be processed (both physical and chemical), and physical and chemical reactions/changes that are taking place in the reactor (heat and mass exchange, chemical reactions, isomorphic change etc.). Each individual piece of equipment must also satisfy specific requirements/ preferences of the client that will operate and maintain the equipment. Those often represent greater challenges than the process on its own, and are equally important to the satisfactory operation of the plant. That includes aspects like location of the equipment, environmental effects, and expected life of the equipment, process control, access, maintenance, and many others.Over the period of time a great deal of research, both theoretical and practical have been carried out and the results of that work are available for equipment designers. For the simple applications that information is usually sufficient and the selection of a suitable solution is relatively simple. In many instances, the available information is not sufficient, and often specialized test work needs to be conducted to obtain additional data. In many cases a pilot installation is built in which the required process is tested. Only then the commercial equipment is designed. The following deal with specific installations that were designed to satisfy specific requirements. In some instances, additional problems were discovered during the commissioning of the equipment that required on site modification. The continuous monitoring of the equipment that was supplied to the various clients allowed us to further develop and improve our designs."

Jan 1, 2014

By William J. Pardee, Michael A. Shaff

"Deeper materials science knowledge from mathematical models and in situ material property sensors will be exploited in next generation factory process controllers to improve productivity and quality. These intelligent control systems will accelerate productivity growth and materials science application through the ease with which they can be modified to accept new materials knowledge and sensors. Carbonization of resin matrix carbon fiber composites, specifically, is a violent solid state chemical reaction with large stresses due to gas pressure, matrix shrinkage, and differences in thermal expansion. The matrix strength falls sharply, then rises again during the process. At least two competing reaction paths are important; the first cleaves methylene bonds, reduces toughness, density and stiffness; the second reforms those bonds, ultimately resulting in aromatic ring condensation that increases density, strength, and modulus. Since these reactions have different temperature dependencies, one can expect to shift the process towards the second path by changing the heating rate, but that change must be accomplished without producing macroscopic interlaminar crack growth. To accomplish this, we employ gas sensors to infer matrix chemical state and acoustic emission to identify microstructural changes and to recognize brittle fracture. The latter does not prevent delamination, but is important in testing models for the causes of delamination and in improving the processing cycle. This paper describes a control strategy to accelerate the process while still lowering the risk of failure.IntroductionDeeper materials science knowledge from mathematical models and in situ material property sensors will be exploited in next generation factory process controllers to improve productivity and quality. These intelligent control systems will be more easily modified to accept new materials knowledge and sensors, thus accelerating productivity growth. Such a control strategy for carbonization control is described below.Carbon-carbon composites are time consuming and costly to manufacture. Processing methods have been developed empirically and are usually very conservative because the process often fails when any change is made. Apparently minor changes in materials or geometry can produce failures that are difficult to diagnose and correct. We will describe below several essentially unavoidable sources of variability. These are best dealt with by applying materials science to adapt (i.e., closed loop control on materials properties) the process in real time to reduce the effect of unavoidable model idealizations, material variability and environmental noise. The most critical issue in control of the carbonization process control is avoiding catastrophic delamination. The strategy developed below makes use of a priori materials knowledge and real time sensors to accelerate the now very slow process without destroying the material, and without requiring unreasonable resources to determine the statistical properties of the material."

Jan 1, 1988

By Suswnu Makino

Sumitomo Metal Mining developed a new nickel refining process ( Matte Chlorine Leach Electrowinning process) based on chlorine leach and electrowinning technologies. After the pilot plant study, the commercial plant with design capacity of 24,000 tonnes per year was constructed and has been successfully operated since August, 1992. During the practice of the past three years, great deals of improvement have been achieved. Through these operations the MCLE process has been demonstrated to be one of the most superior processes in the world with nickel recovery, productivity, cathode quality and working environment. Today the refinery product capacity is increased to 30,000 tonnes per year. This paper describes the equipments and operation of the Sumitomo MCLE process.

Jan 1, 1996

By Tracie Zoeller, G. Paul Neitzel, Jr. Sanders

"As-cast aluminum alloy microstructures are highly segregated. Coring occurs when solute is rejected during solidification resulting in a non-uniform solute distribution across the dendrite arms. Furthermore, coarse constituent phases are formed in the interdendritic channels as a result of coring. These constituents are either soluble or insoluble and can form from the major solute elements, or the impurity elements iron and silicon. The dissolution of these constituents, or precipitates, is an important consideration in determining the microstructural evolution of an alloy. The properties of an alloy are significantly affected by the morphology of the precipitates. Precipitates can be either beneficial or detrimental to the properties of the alloy. Regardless of the nature of the precipitates present, it is useful to understand the dissolution process. A diffusion-limited dissolution model for planar precipitates is presented and compared to an analytical solution and to models in the literature. Experimental data for the dissolution of AhCu precipitates in a dilute alloy are compared to the proposed model, and found to have good agreement.IntroductionDuring the processing of precipitation hardening alloys, beginning with the solidification step and ending with the final solution heat treatment step, there are a variety of particles that form. Some of these particles must be dissolved and solute redistributed and re-precipitated in a more homogeneous distribution than as it first appears in the as-cast microstructure. The particles can be classified by size as microstructure develops during processing. Coarse particles that form during solidification can either be soluble, partially soluble or insoluble. These particles can be the result of coring of the major solute elements as well as the limited solubility of elements such as iron and silicon. Iron and silicon can combine with the major solute elements such as copper in 2xxx alloys forming coarse phases often referred to as constituents. Figure l(a) shows the as cast microstructure with the constituent phases, Al2Cu and the insoluble phases containing Al-Fe-Mn-Cu-Si [7]. During preheating the soluble phases such as AhCu that were formed by eutectic decomposition must be taken back into solution, whereas the insoluble phases remain essentially unchanged by most thermal operations. Figure l(b) and (c) show some of these constituents after subsequent preheating steps. In Figure l(b), AhCu platelets are shown and in Figure l(c) the remnants of the AhCu phase are noticeable, along with Mn-bearing dispersoid phases. Reduction in the volume fraction and size of these phases improves the ductility and fracture toughness as well as reducing the inhomogeneities that occur during coring. Also adjacent to the dendrite arm boundaries are smaller AhCu phases that precipitate by a solid-state transformation on cooling to room temperature."

Jan 1, 2004

By A. Valenzuela

During the last years, Chile has been the largest copper producer, either as concentrates or cathodes. Copper obtained via pyrometallurgy is produced by seven smelters, which have carried out modernization plans to increase smelting capacity or to achieve environmental regulations established in the Chilean legislation. Thus, the present work updates technological innovations in smelters, environmental regulations and presents solutions for SO2 handling, particulate matter and arsenic. Also, the authors emphasize the important role of CODELCO Chile, the most important state-owned copper company, in developing technologies such as EI Teniente Converter and EI Teniente Slag Cleaning Furnace,

Jan 1, 2003

By Tao Jiang

Germanium is widely used in many fields, and the production of germanium is very important. The effects of initial sulfuric acid concentration, liquid to solid ratio and other parameters on the leaching rate of germanium and zinc from germanium-bearing zinc oxide has been studied. The occurrence and form of germanium and other elements in the leach feed and the leach residue were studied by EPMA, XRD and chemical analyses. The experiments showed that the leaching rate of germanium and zinc was 91% and 88%, respectively under optimal conditions. Wurtzite was the main limiting factor for the leaching rate of zinc while the leaching rate of germanium was limited by insoluble germanium compounds. Furthermore, it was found that some germanium was bound up in galena in the leach residue. These results may be helpful for further improving the leaching rate of germanium in germanium-bearing zinc oxide.

By Ignacy A. Lipiec

The advantage of microorganisms used in bioleach systems to conventional chemical reaction systems is that these apply the available energy more precisely where it is needed, either directly onto the mineral of interest or by efficiently catalyzing the production of a reactant. The literature cover the range from empirical models used in describing macro heat balance in heaps to detailed studies relating the micro heat effects of bacteria adhesion energy to the surface of minerals. In this paper, the heat effects are reviewed in a general way describing bioleaching in two macro systems, heap leaching and slurry bioreactors. The micro scale heat effects is the reactions and conditions at the microorganism scale, including the mechanism of leaching and bacterial behavior.

Jan 1, 1998

By Leonard J. Friedman

Modern smelting systems using continuous, flash and/or oxygen smelting processes have a significant effect on the choice of sulfur dioxide control processes and system arrangements. Based on gases from an enriched air or oxygen smelting furnace and copper converters the paper reviews and analyzes alternate processes and system arrangements for recovery of sulfur dioxide. The work indicates the choice system to include a conventional sulfuric acid plant for converter gas and a liquid SO2 plant to handle the high strength smelting fur¬nace gas. The liquid SO2 plant would be used as a fly-wheel to damper the flow and SO2 concentration variations of the con-verter acid plant. Potential energy recovery alternates and product flexibility are also reviewed.

Jan 1, 1983

By Toshia Suzuki, Keiji Kakudate, Yoshihiro Adachi

"A macro model for the steel usage pattern in Japan is proposed. The steels are classified into four types; converter steel for machinery and for construction and electric furnace (EF) steel for machinery and for construction. The steels are assumed to be discharged from the society in accordance with lifetime distributions of each usage. The amount of EF steel and the accumulation in society are calculated using a population balance model. The comparison with the calculated results and statistics ensures the validity of the model. Since the amount of EF steel for construction will increase and be oversupplied, EF steel will have to be used for machinery. The required and available amounts to supply EF steel for machinery are considered from the point of allowable· copper concentration for machinery use. Copper contaminates steel used for machinery during recycling process and contamination ratio is evaluated with the model. Copper concentration in EF steel is predicted for various scenarios.IntroductionThe amount of CO2 emission from Japanese steel industry is 48.0 million C-ton in 1990 and it occupies 15.1% of the total amount in Japan. In order to reduce the C02 emission and to save the natural resources, it is strongly required to promote the recycling of steel. However, the impurity contaminates steel in recycling process and lowers its quality. The copper concentration in EF steel is analyzed by Toi et al. using a macro model with the assumption that steel is discharged in proportion to the accumulation amount [1]. However the discharged amount of products is dependent on their age for service and usage pattern and not on the accumulation amount. In addition, the degree of copper contamination is different depending on the usage of steel. Therefore a precise model that contains the age for service within the society as a parameter and distinguishes the usage· of steel is necessary in order to clarify the problems in the recycling of steel."

Jan 1, 2000

By Georgette Smits

The gun-sprayed refractory lining of electrothermal furnaces used for the manufacture of carbon disulphide from liquid sulphur and charcoal at between 800 and l000°C are severely attacked during the process. A mineralogical study of samples of eroded refractory material disclosed that carbon disulphide had penetrated the lining, causing the precipitation of sulphides and carbon, and the decomposition of mullite, a major constituent of the lining, to corundum and amorphous silica. Calcium, iron, titanium, and chromium are undesirable cations in a refractory that is used in furnaces for the production of carbon disulphide, since they react readily with this substance. A series of tests, in which samples were exposed to different amounts of carbon disulphide for various residence times and at different temperatures, was carried out with eight types of aluminosilicate-based castable and brick refractory materials, to compare their resistance to attack by carbon disulphide. Mineralogical investigation of the test cores showed that castable refractory materials are unsuitable for this type of process because of the presence of calcium aluminates and other impurities in the cement. Of all the refractories that were tested, a mullite brick of low porosity, containing a minimum amount of impurities, appeared to be the most suitable for use in this type of operation.

Jan 1, 1989

By Nobuyuki Higashiyama, Ikuo Yonezu

"Hydrogen-absorbing alloys containing rare-earth elements are used in high capacity nickel-metal hydride secondary batteries,' hydrogen storage systems for portable fuel cells, and refrigeration systems. New hydrogen-absorbing alloys containing rare-earth elements have also been developed and introduced into these applications. High performance in nickel-metal hydride secondary batteries is strongly demanded because of the remarkable advancements in portable electric appliances. A large hydrogen absorption capacity, high electrochemical reactivity and superior corrosion resistance in an alkaline solution are required for hydrogen-absorbing alloys used in nickel-metal hydride batteries. The aim of this investigation is to improve the performance of conventional LaNi5 type hydrogen-absorbing alloys. For example, Mm(Ni-Co-Al-Mn)„ type hydrogen-absorbing alloys with various non-stoichiometric compositions were developed. In addition, a new process of rapid quenching process was applied for preparing these hydrogen-absorbing alloys in order to improve their performance.IntroductionRecently, the trend in electronic appliances toward portability has increased the demand for high capacity of secondary batteries as power sources. Since nickel-metal hydride batteries were first commercialized in 1990 in Japan, they have become increasingly popular as power sources for cellular phones, portable computers, electric shavers, and other, products.The performance of a nickel-metal hydride battery, such as its discharge capacity, high rate capability, and charge-discharge cycle life, strongly depends on the characteristics of the hydrogen-absorbing alloy negative electrode. Many types of hydrogen-absorbing alloys have been developed so far. For a hydrogen absorbing alloy to be used as the negative electrode material, (1) it must allow a large amount of hydrogen to be absorbed and desorbed in an alkaline solution, (2) its reaction rate should be high, and. (3) it must have long term durability under repeated charge-discharge cycling. However, LaNi5, a typical rare earth-nickel type alloy, shows significant capacity deterioration during repeated charge-discharge cycling. Therefore the first step in its development was to obtain sufficient corrosion resistance of the LaNi5 alloy for its use as an electrode material. A partial replacement of nickel with cobalt and a substitution of the lanthanum- content with misch metal (Mm), a mixture of rare earth elements such as lanthanum, cerium, praseodymium and neodymium, were very useful in improving the charge-discharge cycle life. However, the discharge capacity of the alloy was still not sufficient for a practical battery. A study of the effect of the partial substitution of aluminum and manganese showed that the best alloy composition was Mm(Ni-Co-Al-Mn)x, as follows.The stoichiometry x of Mm(Ni-Co-Al-Mn)x largely affects the discharge capacity and cycle life. Theose alloys with non-stoichiometric alloys with the compositions of [Mm(Ni-Co-AMn)x: 4.7<x<4.8] have a large capacity and a long cycle life. Nogami' et al. reported that 'a non-stoichiometric alloy with a Mm(Ni-Co-Al-Mn)x (x=4.76) composition showed approximately 10% higher discharge capacity than the stoichiometric alloy (x=5) [1] and greater influence of x on the electrochemical properties of multi-component AB„ type hydrogen-absorbing alloys for batteries."

Jan 1, 2000

By D. C. Foguel, J. L. R. Bravo

For several years, Caraiba Metais S.A. (CMSA) had to stock the arsenic sludge generated from the electrolyte purification process of its tankhouse. The amount stocked · reached approximately 3,500 tonnes, as the effects of its recycling during the smelting process and consequently in the sulfuric acid plant were unknown. Besides, it had as limiting factors the high content of arsenic in the copper concentrates supplied by foreign countries as well as the reduced capacity of the tankhouse's purification plant. The choice for selling the mentioned residue, which generally contains more than 50% of Cu, was attractive, but the environmental policies and regulations had not allowed this option. Other alternatives, such as the production of bicupric arsenic by means of a solvent extraction process or arsenic trioxide, were considered but the economic feasibility was not attractive due to the absence of a domestic market and a poor international market. After a study of the arsenic partition in the metallurgical process, it was verified that the residue could be recycled without causing any operational problems or damage to the environment. To make this possible, the capacity of the purification plant was increased and the way of removing the arsenic sludge from the cells was modified from manual to mechanical, therefore avoiding the direct contact of the workers with this poisonous substance. Moreover, procedures for recycling in the smelter were established and tolerance limits were set for both the smelter and the sulfuric acid plant. The main amount of arsenic to be recycled is released with the smelting furnace off-gas, which is washed during the purification stage of the sulfuric acid plant. The acid water, rich in arsenic, is then treated in the waste plant and the arsenic, in its stabilized condition, is confined in an appropriate area.

Jan 1, 2000

By A. V. Tarasov, S. D. Klushin

493 The most common method for minimizing the copper content of residual slag in the process of autogenous smelting of sulfide raw materials is treatment of molten slag in an electric furnace, with optional addition of solid reducing agents, such as coke, and/or sulfiding agents such as pyrite. A drawback of this technique is the fact that the final slag produced still contains 0.5% or more Cu. We have tested a method for treating molten slag obtained as a result of autogenous smelting by a gaseous mixture of sulfur dioxide and methane at a ratio of. SC:SO2 = 0.75 :1.0 in the presence of oxygen. Interaction reaction within the SO2-O2-CRi system proceeded at a high rate at 1373 to 1573 K to form reducing and sulfiding agents: H2S, S, COS, CO, CO2, H2, H2O. The gas mixture requirement was about 100 to 150 Nm3 per 1 tonne of slag. A decrease in the ferric iron concentration (Fe3+) from 10-15% down to 2-3% resulted in lower solubility of copper in slag, and agitation of the melt with gas stream accelerated. the separation of the sulfide phase and slag. Removal of copper from slag was performed in a pilot unit within the second V anyukov furnace zone where slag arrived with a copper content of 0.8-1.3%. The temperature of molten slag was maintained within 1523 to 1573 K. The copper content of the final slag was at a level of0.12 to 0.14%. The matte sent to converting was a mixture of bottom matte from the smelting zone and the slag treatment zone. It had a copper content of about 50 to 55%. Process gases from both furnace zones were combined and sent to the acid plant for sulfur recovery. This process was offered for commercial use at two copper smelters in Russia and CIS.

Jan 1, 2000

By Keiji Okumura, Hong Lan, Masamichi Sano

"Magnesium has been well known as one of the excellent agent of desulfurization, deoxidation, etc. in iron- and steelmaking because of its high reactivity. Since its production is energy nitensive, the price is very high. Thus magnesium has not widely been used as an agent in metal refining ·processes. In the present work, reduction of magnesia by carbon and aluminum is examined. Because the reaction is very sensitive to temperature, non-isothermal technique is applied to investigate the reaction kinetics. The effects of heating rate .and reaction interface area on the reaction kinetics .are studied. .A kinetic model is proposed based on the experimental results.IntroductionFor the metal refining processes, the production of high purity metal has been one of the most important research subject. In order to produce the high purity metal, the amount of the refining agent and the consumed energy is increasing. Therefore, if the future earth environment is taken into consideration, the further efficient and energy saving processes are required. Generally, Cao slag has mainly been used for desulfurization of molten iron as a desulfurization agent. However, environmental problems, such as recycling of disposal slags, are still unsolved. On the other hand, the deoxidation of molten steel is mainly performed by addition of aluminum. Therefore, the alumina inclusions· remain in. molten steel and the great efforts have been made to the removal of the inclusions. The affinity of magnesium with sulfur and oxygen is strong, and magnesium is well known as a powerful desulfurization and deoxidation agent. However, magnesium has been seldom used for the steel' refining process. The following reasons are considered. Generally, magnesium is expensive. And at iron- and steelmaking temperatures, the refining efficiency becomes low due to its abruptly .evaporation."

Jan 1, 2000

By Thomas M. Harris

Cation exchange is not sufficiently selective to be used for the removal of heavy metal ions from a general industrial wastewater. However, if the metals can be converted to polyvalent anions through complexation, they may be removed both selectively and efficiently by anion exchange. This approach, referred to as chelation-assisted anion exchange (CAAE), has been examined using industrial wastewater samples contaminated with Ni2+ and Cr3+. For this particular application, the Ni2+ is complexed with 8-hydroxyquinoline-5-sulfonic acid, and the Cr3+ with sulfosalicylic acid. Removal efficiencies and adsorption isotherms for both the complexants and the complexes were determined in batch-mode tests.

Jan 1, 1994