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By Y. C. Avniel, T. E. Warner

"It is important to be able to measure sulphur and nitrogen in molten iron and steel on-line. Unfortunately, there are no solid electrolytes which are stable under oxidising conditions and in which the ions of these species are mobile. In this paper, novel applications of beta alumina electrolytes are described and the results compared with data in the literature. Excellent agreement was obtained confirming this approach as a viable method of detecting elements whose ions are not mobile in solid electrolytes.IntroductionIn the past two decades, the rate of many processes in steelmaking have increased substantially. The sophistication of chemical analysis has also increased but analytical equipment is frequently positioned a significant distance from the operating plant which dictates that time is spent taking a sample, sending it to the analytical facility, preparation of the analytical sample prior to insertion into the equipment. In many cases, the time taken for analysis can exceed the time taken for the actual process and is now the rate defining step. Furthermore, most analytical methods are unable to distinguish between the amount of element which is dissolved in the steel and that contained in precipitates. Even if the analytical equipment could separate these two, the distribution would have changed between the molten steel and the cast sample. It would be an advantage to analyse on-line for impurities in molten metals."

Jan 1, 1997

By P. Hajiani

Rare earth elements (REEs) are critical materials in many leading-edge technology products. However, REE separation outside China has remained a challenge in addressing environmental concerns of current production. The author has worked on a technique employing the emphasised variability in the electrophoretic mobility (μi) of REE for the purpose of REE separation. In continuation of the results presented in IMPC 2016 [1], this contribution summarizes the progress achieved in 2016 and 2017. The major goal was to increase the REEs concentration by a factor of 1000 and to attenuate the consequent drawbacks, specifically joule heating effect. Amphiprotic hydroxylic solvent was selected to replace water, which has a major impact on the complexation mechanism and buffer requirement. Non-aqueous media result in a significant drop in the specific molar conductivity of the electrolyte, whilst μi reduces several times only. Moreover, a quasi-steady state electrophoretic separation in conjunction with temperature gradient focusing is adapted to improve scalability.

By V. I. Lakshmanan

The demand for elements such as nickel, cobalt, titanium and gold in various applications has increased significantly. Innovation to recover these elements now plays a major role in metallurgical processes as established technologies have challenges in treating the types of ores that are available while meeting the increasingly stricter environmental regulations. Alternative chloride based processes have been developed that can be used to recover the value elements from the available feed stocks with potentially lower environmental impact. Chloride-based hydrometallurgical processes have several advantages, including higher leachability of complex ores/tailings and relative stability of chloro-complexes of the metals. Process Research ORTECH Inc. (PRO) has developed mixed-chloride process flowsheets, where innovative solvent extraction process steps are used for the separation of nickel, cobalt, titanium and gold from their respective chloride solutions. This paper will discuss the potential aqueous chloro-chemistry of these metals and separation reaction mechanisms involved in the solvent extraction process.

By Sungdon Kim, Chuljoo Kim, Joonsoo Kim, Hosung Yoon

"This study was performed to establish the optimum leaching condition through the experiments for the oxidized roasting followed by leaching of fluorocarbonate rare earth mineral (bastnasite) using sulfuric acid, and to establish the optimum condition for the recovery of cerium by ion- sieve method from the leached solution of bastnasite. The optimum conditions for the sulfuric acid leaching by the oxidizing roasting of bastnasite concentrates are that the roasting temperature is 550 -600 °C, the roasting time is 2 hrs, the concentration of sulfuric acid is 6N, the leaching temperature is S0°C and the leaching time is 3 hrs. At this time, the leaching yield of total rare earth oxides in the leaching of bastnasite concentrates is about 91%. When cerium is recovered by ion-sieve method from the solution obtained by the sulfuric acid leaching of the roasted bastnasite, the optimum conditions are that the TREO(total rare earth oxide) of leached solution is below 70 g/l, the flow rate of leached solution is 9.6 ml/min and the ratio of height to diameter of resin packed in column is above 9. In these conditions, the recovery of cerium of yield 85% and purity 96% is possible.IntroductionThe rare earths are generally called to Lanthanides, which are totally 17 elements including Scandium of atomic number 21 and Yttrium of atomic number 39 in addition to 1 S elements from Lanthanum of atomic number 57 to Lutetium of atomic number 71. Since the separation to each element is very difficult because of their similar chemical properties, the rare earths were used as the mixed rare earths and the mischmetal without separating to each element. However, the high purity rare earths are recently produced commercially to each element so that they are used as the materials for high tech. industry such as electric and electronic materials, catalysts, optical materials, special alloy and 8Uperconductive materials, and their consumption is rapidly increasing. Therefore, the purpose of this study is firstly to prepare leached solution by using the series of process of the oxidation-roasting and leaching by sulfuric acid. Next, second purpose is the separation and recovery of cerium by ion-sieve method."

Jan 1, 1998

By Katsutoshi Inoue

The sulfuric acid leaching of spent hydrodesulfurization catalysts yields an acidic solution rich in rare metals such as molybdenum, vanadium, cobalt, and nickel in addition to aluminum. For the purpose of separating and recovering the rare metals from the solution, basic solvent extraction characteristics of the metals involved with commercially available acidic organophosphorus reagents like TR-83, PC-88A, PIA-8 and CYANEX 272 as well as aliphatic alpha-hydroxyoxime LIX 63 from sulfuric acid media were investigated in the present work. It was demonstrated that CYANEX 272, PIA-8 and LIX 63 possessed excellent selectivity for molybdenum and vanadium over the other metals at comparatively low pH. Further, recovery of molybdenum and vanadium from the total leach liquor by the selected extractants was discussed. Additionally, in order to achieve preferential separation and recovery of cobalt and nickel over an appreciable amount of aluminum from the raffinate obtained after recovering molybdenum and vanadium, a systematic investigation was conducted on synergistic extraction behaviors of the mixed solvents of LIX 63 in combination with a series of acidic extractants such as CYANEX 272, PIA-8, PC-88A, D2EHPA, TR-83 and OPEHPA for cobalt, nickel and aluminum. It was elucidated that all of these mixtures could exhibit a good synergistic effect for extraction of cobalt and nickel, and that the lower the pKa of the acidic extractants, the greater the synergism. Contrarily, the extraction of aluminum, was considerably suppressed by LIX 63. Effective extraction of cobalt and nickel away from aluminum was accomplished from the sulfate solution at low pH (1.0 - 2.5) with the mixtures. In particular, the mixtures consisting of LIX 63 and CYANEX 272 or PIA-8 appeared to be the most feasible and economic from an industrial point of view, yielding acceptable separation efficiency for cobalt and nickel over aluminum and .a low acidity requirement for stripping cobalt and nickel as well as negligible degradation of LIX 63. Aluminum can be readily recovered as sulfate salt from the raffinate obtained after recovering molybdenum, vanadium, cobalt and nickel as outlined above by conventional crystallization method.

Jan 1, 1995

By Jiang Fan, Wang Haigang

"The three-dimensional complex multiphase turbulent flow in U-beam separators was simulated using the Reynolds stress equation models (RSM). To account for the effect of the stochastic characteristic of the instantaneous gas velocity on the particles, the improved Lagrangian stochastic model based on the Reynolds stress model for gas phase was adopted, which attributed to the successful prediction of the turbulence anisotropy and particle crossing trajectories effects. The interaction between the particles was also considered using the HardSphere model. To treat the particle-wall collision, the influence of the roughness of the wall on the motion of the solid particles was taken into consideration by imposing random collision angles. The result from this study not only shows the dynamic characteristics of the multiphase flow- in the separators, but also gives the relationship among the efficiency, structure and pressure losses of the separator.IntroductionCirculating fluidized bed (CFB) combustion is one of the most promising clean coal techniques. A main feature of CFB boilers is the un-delayed recycle of solid, coal and sorbant particulate, in an external loop. Separator, which is required to separate the solid particle from the flue-gas leaving the reactor of CFB, plays an importance role in the external solids recycle loop. It affects the combustion of CFB system greatly. Presently cyclone is the most commonly used as separators for CFB system and other chemical industrial processes. It provides high level of separation for CFB system for fine particles. However it suffers from some inherent disadvantages. It's volume and size is huge. Moreover, it is difficult to design and install when the CFB workload rises. The application of U-beam separators instead of hot cyclone separators in CFB boilers has many advantages. Publications indicate proposals or successful use of Ubeam separators in Swedenr11, USA 21, Russia r3land China [4]• But it is not possible to find results in the literature of detailed investigations of this new. type of separators or recommendations on the choice and calculation of an optimal design. For this reason, numerical simulation for the three-dimensional gas-particle two-phase flows with several rows of vertical U-beam elements, local in the chess order and blocking a way of outgoing from a CFB boilers dusted gases was carried out in this study."

Jan 1, 2004

By C. H. Quan

Solvent extraction tests were carried out on a rare earth chloride solution derived from monazite processing to determine the effect of extractant and diluent on the distribution coefficients between organic and aqueous phases, and the separation factor between rare earths. The extractants were 20% by volume di-2-ethyl-hexyl phosphoric acid (DZEHPA) or 2-ethyl-hexyl phosphonic acid (Ionquest® 801). Four Shellsol diluents were tested ranging from nil to 100% aromatic content. D2EHPA gave the highest rare earth extraction for a given pH but was less selective than Ionquest. The geometric mean separation factor between adjacent rare earths varied from 2.41-2.56 for D2EHPA to 2.62-3.01 for Ionquest. The nil-aromatic diluents (Shellsol 2037 and 2358) gave better separation factors in Ionquest but, in D2EHPA, were slightly inferior to the 100% aromatic diluent Shellsol AB. Yttrium behaved as a pseudo-heavy rare earth with a distribution coefficient lying between Ho and Er, as expected from its ionic radius.

Jan 1, 1992

By Chuanlin Fan

The process of flotation separation and recycling of spent potlining (SPL) was described. On the basis of the laboratory investigations, the effects of influencing factors in froth flotation process, such as grain size, flotation agent dosage, pH value, pulp density, and dissolved components concentration, etc, were carefully studied. And the influence on environment of the process was also discussed. It was found that flotation separation can be used as an environment-friendly method for treatment of SPL residue. Carbon and other compounds (include cryolite, sodium fluoride, calcium fluoride and diaoyudaonite, etc.) from SPL were separated and recycled as flotation products respectively.

Jan 1, 2009

By G. N. Shannon

Keywords: inclusions, slag, modeling, interfacial energy, capillary force, particle flotation, particle separation A previously introduced model of inclusions separating across a steel-slag interface, developed by Nakajima/Okamura and Bouris/Bergeles, is expanded to include different inclusions shapes (octahedral and plate-like, besides spherical) as well as comparison between model ladle-, tundish-, and mold-slags. Investigation of the relation of these shapes with the interfacial capillary force ? which arises due to the dynamic interfacial energy during separation ? has shown that the force has a significant effect on whether the inclusion separates rapidly or settles at the interface. For the slags considered, the most significant physical property is found to be viscosity, which resulted in fast separation times for inclusions in the mold and ladle slags, relative to the more viscous tundish slag. Particle dissolution (using experimental data) is included in separation modeling.

Jan 1, 2005

By A. S. Block-Bolten

Two innovations in nickel-arsenic separation have been studied on a laboratory scale. The first requires only a nitric acid atmospheric leach without preliminary roasting and leads to favorable final conditions for precipitation of arsenic as highly stable FeAsO4, The second is an NaOH-H2O2 pressure leach which is an alternative to the known NaOH-O2 pressure leach. Either method offers the possibility of rapid and efficient separation of nickel from arsenic and is applicable, for example to the high grade niccolite deposits in the Great Slave Lake area of northern Canada.

Jan 1, 1982

Sanes are utilized to make molds for metal castings in the foundry industry. Approximately a half ton of sand is disposed of for each ton of metal cast in this country. The purpose of this investigation was to study and develop a process to separate chromite sand and silica sand from reclaimed sands for a steel foundry. Physical separations were utilized to yield silica and chromite sands with desirable molding properties. Several different separation methods, including electrostatic, magnetic, and various gravitational approaches were examined. Experimental results are presented. A method was developed to separate chromite sand from silica sand after mechanical or thermal reclamation. The reclaimed sands are passed through a rare earth magnetic separator to separate chromite sand and magnetic impurities from non-magnetic silica sand. Chromite sand can be recovered from magnetic silica sand or magnetic impurities very effectively using a wet concentrating table. The applicabilities of the separation methods are discussed.

Jan 1, 1995

By Zizheng Zhou

The separation of cobalt from other base metals can be achieved using diffusion dialysis in a two-compartment reactor separated by an anion exchange membrane. In this work, a Neosepta AFX membrane was used to study the separation of various metals in an acid-chloride solution. The separation of one metal from another was investigated on the basis of the various chloro-complex stabilities. The metals investigated included cobalt, nickel, copper(II), iron(III), aluminum, zinc and cadmium. The impact of several critical experimental conditions, including the initial metal and chloride concentration in the feed solution and their initial concentration in the receiving solution, on the separation factor and the metal transfer rate is reported in this work. Effective separation of different metal pairs was achieved under the experimental conditions.

By Juan Patricio Ibáñez

Separation of arsenic and copper from Cu-As-H2S04 electrolytes by electrodialysis has been investigated at room temperature. The effects of current density and pH were studied. An arsenic-free copper solution was obtained for all the tested conditions. The transport efficiency for copper ions was found to be higher than 98% after 3 hours' test. Transport of arsenic and copper through the ion exchange membranes was increased by increasing pH and current density. Solution pH was found to be a key parameter for the separation process, since it controls the speciation of the ions to be transported and the formation of unwanted precipitates which reduce the global efficiency of the electrodialysis process. The main conclusion is that electrodialysis is a promising technique to be used in separating and/or concentrating ions of interest in copper electrometallurgy.

Jan 1, 2003

By Chen Song

Keywords: Mixed extractant, Copper, Cobalt, Nickel, Synergistic effect During separation process of copper and cobalt from nickel sulphate solution, the effects of constitutions and compositions of mixed extractant D2EHPA and PC88-A or Cyanex 272, has been studied. In one step extraction cycle, the following results are obtained:[Ni]/[Co]>4000 and [Ni]/[Cu]>40000 in nickel sulphate solution, [Co]/[Ni]>1000 and [Co]/[Cu]>30000 in cobalt chlorinate solution, [Cu]/[Ni]>10000 and [Cu]/[Co]>200 in copper sulphate solution. It was elucidated that the above-mentioned synergistic mixtures can effectively separate cobalt and copper from nickel sulphate acid solution and achieve a greater synergistic effect.

Jan 1, 2005

By Junji Shibata

Heavier rare earth, which is contained in a small amount in ores such as bastnesite and monazite, has been accumulated as a heavier rare earth residue without doing separation and purification due to the lack of suitable methods. The heavier rare earth residue includes seven rare earth elements such as Tb, Dy, Ho, Y, Er, Tm and Yb. Separation and recovery process of Dy, Y, Tm and Yb from leached solution of the heavier rare earth residue was investigated by using a column method with solvent impregnated resin. The solvent impregnated resin was prepared by impregnation of organophosphorous extractant whose trade name is PC-88A into a macro porous resin, Amberlite XAD-7. It was almost impossible to separate them in simple adosorption and elution steps. However, we attained to individually separate Dy, Y, Tm and Yb from the leached solution first by changing eluent concentration gradually from pH2 to 0.02kmol/m3 HC1 in the elution step, and secondly by using a development column and changing eluerit concentration in the elution step. The separation process flow was proposed for a heavier rare earth residue by using the solvent impregnated resin method.

Jan 1, 1998

By Toshihide Takenaka

The management of radioactivated stainless steel from a terminated nuclear reactor will become an important subject in the near future. The separation of the elements in stainless steel should be effective to reduce the management labor. In this study, the separation of the elements in stainless steel by an electrorefining tcchnique was investigated in an aqueous solution. The electrochemical reactions of the elements in stainless steel werc studied by voltammetry and potentio-static electrolysis was carried out. A stainless steel anode was dissolved electro-chcmically with good anodic current etliciency in a chloride solution. The residue, where Ni was concentrated, was found on the anode after electrolysis. The electrodeposit in a stainless steel cathode consisted mainly of Fe and Cr and the Ni content in it was less than 0.5wt% under suitable condition. It is concluded that an electrorefining technique is effective for the separation of the elements in stainless steel.

Jan 1, 2003

By Xuemei Zheng, Aiyuan Ma, Chao Liu, Guojiang Li, Chenyu Sun, Jinhui Peng, Libo Zhang, Yongguang Luo

In this paper, the removal of fluorides and chlorides from blast furnace dusts by water vapor enhanced microwave roasting was investigated, combined with the advantages of microwave selective heating and based on a thermodynamic analysis of zinc and lead halides. According to proposed reactions in the process, detailed experiments were systematically conducted to study the effect of roasting temperature, holding time, air flow, water vapor flow rates, and stirring speed on the efficiency of the removal of F and Cl. The results show that 97.26% of F and 64.23% of Cl could be separated when the condition of the roasting temperature of 650°C, stirring speed of 80 rpm, holding time at 60 min, air flow of 350 L/h and water vapor flow rate of 8 mL/min was optimized.

Jan 1, 2016

Plastics recycling has become an established national industry in Korea. However, it is still in its infant stage and experiences growing pains. In Korea, mixed plastic wastes generated from households after hand picking and/or mechanical sorting processes amount to 1,700,000 ton per year in 2005, and most of these waste are finally end up with landfill and/or incineration due to lacks of separation technologies and economical reasons. These plastic wastes can not be used as raw materials for chemical and/or thermal recycling because of their high content of PVC (upto 4.0 wt.%). In the present work, gravity separation system has been developed to remove PVC from the mixed plastic waste and recover the individual plastics. The separation system mainly consists of air classification, crushing, feeding system at fixed rate and wet-type gravity separation system. The gravity system based on centrifugal separation also consists of mixing, precleaning, separation, dewatering, recovery system, wastewater treatment system, etc. The main objective of this process to be developed is to achieve high separation efficiency of polyolefins (PE, PP, PS) with less than 0.3 wt.% PVC content and less than 10% moisture content in the final products. The system with a capacity of 0.5 ton per hour is developed and operational results are presented.

Jan 1, 2006

By Zhigan Deng

Cooling crystallization was used to separate iron (III) and nickel (II) from acidic sulfate solution produced by leaching of molybdenum-nickel black shale. The effect of K2SO4 concentration, crystallization temperature, solution pH and crystallization time on recovery of nickel (II) and precipitation of iron (III) was investigated, in order to obtain effective separation of nickel and iron. The optimum parameters determined were as follows: 200 g/L K2SO4, 10 °C crystallization temperature, solution pH of 0.5 and 24 h crystallization. Under these conditions, 97.6% nickel (II) was recovered as K2Ni(SO4)2, 6H2O crystals and only 2.0% of the total iron (III) was precipitated. Recrystallization yielded K2Ni(SO4)2, 6H2O crystals with a purity of 98.4%.

By K. Verbeken, E. Wettinck, M. Verhaege

Iron (III) can easily and selectively be removed from acidic sulphate solutions with organo-phosphoric acids like Di-2-Ethyl-Hexyl-Phosphoric Acid [D2EHPA]. Stripping of the iron (III) loaded organic, however, is difficult unless highly concentrated inorganic acid solutions are used. In this paper results are shown for the enhanced stripping of iron from loaded D2EHPA by electro-reduction. The loaded solvent is contacted with a 2 M H2SO4 solution, which is continuously recycled in an electrochemical reactor where iron (III) is reduced to iron(II). As iron (II) is not extracted by D2EHPA, the equilibrium for iron (III)- D2EHPA is shifted towards the aqueous iron (Il)-sulphuric acid solution. The electro-reduction unit is a vessel with separated catholyte and anolyte chambers. The catholyte is the actual stripping solution where iron (III) is reduced to iron (II) on a stainless steel electrode. The anolyte is a 2 M H2SO4 solution where oxygen is evolved on a lead alloy electrode. A sintered glass plug separates the compartments. With this unit, enhanced stripping of iron from the solvent is possible under mild acid conditions [2 M H2SO4], and a concentrated ferrous sulphate solution can be obtained. The results shown have mainly been obtained by studying the parameters affecting the electro-reductive stripping of a D2EHPA loaded organic phase in a batch reactor. From an iron (IH)-saturated 20 vol. % D2EHPA solvent containing ~ 12.5 g/1 Fe (III) over 90% of the iron can be stripped in one stage with a 2 M H2SO4 solution at 50°C. It is shown that in this way it should be possible to obtain a concentrated ferrous sulphate solution which can be processed downstream to recover a pure iron product.

Jan 1, 2000