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By Andreas Weber

Batrec operates a plant for the recycling of used dry batteries with a capacity of 3000 tons per year. The plant Is situated In a tourist area of Switzerland and has complied with all the strict emission restrictions. The process yields four products: FeMn. Zn, Hg and slag. No hazardous waste Is produced. All types of batteries can be treated.

Jan 1, 1995

By Alicia Esther Ares, Alex Iván Kociubczyk, Verónica Liliana Scheiber, Roberto Rozicki

In the present research the horizontal solidification of Sn-Zn eutectic alloys (Sn-8.9wt.%Zn) is performed, with two opposite senses of heat extraction. From the process of solidification, the thermal parameters (local solidification time, cooling rates and interphases velocities) and grain sizes from macrostructures obtained were determined. The presence of defects in the solidified samples was analyzed, observing that they occur largely in the collision zones of solidification fronts advancing in opposite directions in the samples.

Jan 1, 2016

By Alfonso Nájera

Turbulent flow of liquid steel and its control is studied using different geometries of turbulence inhibitors. Four designs of turbulence inhibitors were characterized through experiments of tracer injection I a water model and mathematical simulations using the Reynolds Stress Model (RSM) of turbulence. Geometries included octagonal-regular, octagonal-irregular, pentagonal and squared. A layer of oil was used to model the behaviour of tundish flux during steel flow. Fluid flows in a tundish using these geometries were compared with that in a bare tundish. Experimental and simulation results indicate that the flow in the bare tundish and a tundish using turbulence inhibitors open large areas of oil due to strong shear stresses at the water-oil interface but the squared inhibitor. These phenomena are explained by the high gradient of the dissipation rate of the turbulent kinetic energy using the squared inhibitor. Using this device the kinetic energy reports a high gradient from the tundish floor to the free bath surface as compared with other geometries.

Jan 1, 2006

Today’s world relies upon advanced green technologies that are made of critical elements with unique properties. Examples include rare earth elements (REEs) that are critical in the manufacturing of wind turbines and electric/hybrid vehicle batteries, key components of a greener future that face supply uncertainty and near zero recycling. To tackle their supply challenges, activities have begun for urban mining from waste electrical and electronic equipment (WEEE) that contain considerable amount of REEs, but their current level of recycling is less than 1%. Current recycling practices use either pyrometallurgy, which is energy intensive, or hydrometallurgy that utilizes large volumes of acids and solvents and generates large volumes of hazardous waste. In this study, we developed a novel and sustainable process to recycle REEs from WEEE, NiMH batteries in particular. The developed process relies on supercritical fluid extraction (SCFE) utilizing CO2 as the solvent, which is abundant, safe, cost effective, and inert. The effect of seven operating parameters, namely temperature, pressure, residence time, sample to chelating agent ratio, agitation rate, complex formulation, and methanol addition on REE extraction efficiency was investigated, and optimum operating conditions were determined. This work is the first to utilize a very efficient and safe process that runs at low temperature to extract metals from postconsumer products with minimum hazardous waste generation, while offering about 90% leaching efficiency for REEs. We expect our process to find widespread applicability in urban mining of REEs using green chemistry.

Direct electrowinning is an electrochemical process which has been developed for the extractive recovery of copper from dilute, acidic leach solutions. In passing through a thin particulate coke cathode. copper is reduced and electrodeposited in a thin layer forming a solid copper-coke sheet. The product is melted in a furnace to separate the coke, then the molten copper is fire refined to produce a salable product. A description is given of a prototype unit which is designed to treat 20 gpm leach liquor and recover over 100 pounds of copper per day. Economic analyses show that in a commercial facility producing about 25.000 TPY copper.*the direct electrowinning process has lower overall cost than either conventional iron-cementation or the newer liquid ion exchange-electrowinning when the leach liquors contain less than 2 grams per liter of copper.

Jan 1, 1976

By Wantae Kim, Furnia Saito, Qiwu Zhang

"A novel mechanochemical processing technique for the preparation of zeolites from kaolinite in NaOH solution was investigated. Dry and wet mechanochemical treatments combined by subsequent moderate heat treatment could accelerate the synthetic reaction for zeolites from kaolinite. This stimulating process produced zeolite-A and zeolite-X from activated kaolinite at extremely lower reaction temperature than conventionally applied for zeolites production. Conversion to zeolite-A and zeolite-X was strongly dependent on the activated state of kaolinite. Wet mechanochemical treatment modified the chemical composition of activated solids. Rapid dissolution of AIO species rather than SiO ones in the reactant solution was accelerated by wet milling together with NaOH that promoted the formation of zeolite-X of high specific surface area.IntroductionZeolites are a family of hydrated alumina-silicate minerals contains alkali and alkaline earth metals. They have a framework structure that encloses inter-connected cavities occupied by large metal cations and water molecules. Zeolites are characterized for their ability toward ion exchange and reversible dehydration. Properties of them are exploited through commercial productions of particular structural and chemical features. Zeolites are used as commercial uses for catalysis for FCC (fluidized catalytic cracking) of petroleum refining, drying reagents of gases and liquids, and selective adsorbent for pollution control [1-3]. In such purposes, artificially synthesized zeolites are employed, although natural ones are associated with hydrothermal and hot spring alteration of volcanic materials. Commercially, a hydrothermal process has been used for the preparation of zeolite synthesis. This preparation method gives zeolites of high chemical homogeneity and purity, however, this wet-chemistry-based processing is significantly influenced by reaction temperature, pH, concentration, and composition of starting substances [4]."

Jan 1, 2000

The oxidation of ferrous ions by oxygen in sulphate solutions is a very slow process, but it tills long been known that the addition of sulphur dioxide increases the rate of reaction very significantly. The kinetics and mechanism of the process were investigated in the laboratory and the results confirmed the advantage of adding small amounts of sulphur dioxide to the oxygen stream for the removal of iron from solutions. The effect of various parameters on the overall rate of iron oxidation and precipitation was studied. In particular, temperature, acidity and composition of the gas mixture were considered and the optimum conditions for the precipitation of goethite were determined.

Jan 1, 1991

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 Chang Wei, Fan Zhang, Zhigan Deng, Minting Li, Cunxiong Li, Gang Fan, Xingbin Li

Marmatite is an important resource of zinc, which exist in forms of high iron and high indium. In order to recycle the valuable metal from these ores, the testwork of simultaneous leaching on neutral residue mixed with zinc concentrate of high iron and high indium has been conducted. The primary objectives are to leach the zinc and indium remaining in the neutral leach residue as ferrite using acid, and to reduce the ferric iron in solution to the ferrous by zinc concentrate, thereby extracting the zinc and indium in the zinc concentrate. The results indicated that in the following conditions, mass ratio of neutral residue to zinc concentrate of 1:0.25, particle size of 74-58 μm, initial sulfuric acid concentration of 150 g/L, liquid to solid ratio of 8 L/kg, temperature of 90°C, reaction time of 4h, the leaching efficiency of zinc and indium were over 95%, nearly 90% Fe was Ferrous in the leaching solution. This process effectively extracted zinc and indium and converted Fe3+ into Fe2+ in solution, and simplified the traditional process of reduction after leaching.

Jan 1, 2016

By Tom McCullough

The purpose of this paper is to discuss the implementation and results derived from installing oxy-fuel burners in a l80 ton copper reverbatory melting furnace. Specific results will be discussed in the areas of melt chemistry, furnace modifications, productivity, process enhancements, and the combustion system capabilities.

Jan 1, 1996

By A. J. Duncan, S. Viswanathan, Q. Han

"Measurements of liquid permeability in the mushy zones of Al-15.42% Cu and Al-8.68% Cu alloy samples have been performed isothermally just above the eutectic temperature, using eutectic liquid as the fluid. A modified method has been developed to determine the specific permeability, Ks, as a function of time during the test from the data collected on these alloys. Factors affecting permeability measurements are discussed. Permeabilties are observed to vary throughout the experiment. This is attributed to rnicrostructural coarsening and channeling that occurs in the sample during the experiment. The permeability is related to the rnicrostructure of the sample using the Kozeny-Carman equation. The correlation between the measured Ks, liquid fraction, gL and the specific solid surface area, Sv, improves markedly when compared to previous studies in which rnicrostructural coarsening was ignored.IntroductionThe permeability of interdendritic liquids flowing through dendritic structures ·is an important parameter needed to predict the level of porosity in castings. The permeability is a component of Darcy's Law, used to estimate the pressure drop due to the resistance to the flow of interdendritic fluid to feed shrinkage. Therefore, much research has focused on measuring the permeability of alloys in the mushy zone (1-10). The Kozeny-Carman equation for liquid permeability in the mushy zones of alloys may be written as"

Jan 1, 1999

By Dan Wang, Qian Xu, Guangshi Li, Xionggang Lu, Xingli Zou, Zhongfu Zhou, Hongwei Cheng, Changyuan Lu

The preoxidation of the ore has a profound significance to the concentration, separation and purification of nickel and copper from the lean complex ore. In this paper, the natural Ni-Cu sulfide mineral samples under the elevated temperature condition in air were investigated, as well as under isothermal condition at 600 oC in air. The mineralogical characterization was studied using XRF, ICP and the Rietveld method. The oxidation behavior and the element migration of the Ni-Cu sulfide ore were studied by XRD, SEM-EDS and TG. The XRD Rietveld method was successfully developed in the phase identification and quantification of this complex ore powder sample. The oxidative intermediates (Cu/Ni-ferrite) were detected by XRD, and the process of the element migration was obviously revealed by the line scans using SEM-EDS. It is the preoxidation of this mineral that provides guidance for the extraction of valuable metals from low-grade Ni-Cu sulfide ores in the future.

Jan 1, 2015

By A. Mikula, S. Karlhuber

"Unique physical and mechanical properties made the Pb-Sn solders attractive for low temperature joining of electronic parts. But since lead in solder materials has become a great enviromental problem and health concern, lead will be slowly replaced by other materials in soft solders. Some of these materials which are currently under investigation are ternary tin alloys. Many different physical properties like wetting behavior, electrical and thermal conductivity and surface tension are measured on these alloys, but on the thennodynamic properties and the phase diagram of the alloys under discussion there is only little information available. We investigated the (Ag, Au, Cu)-Sn-Zn systems and determined the thermodynamic properties over the whole composition range by emf-measurements. From these measurements we also got some information on the liquidus. In the Sn-rich corner the phase diagrams are still under investigation.IntroductionSoldering is technically defined as the joining of two base materials, mostly metals or metal coated nonmetallic substrates, with a third metal. The melting temperature of the third metal or metal alloy should be well below those of the substrates. Solder alloys can be categorized in soft and hard solders. Soft solder alloys usually contain lead, tin, bismuth, indium or cadmium and hard solders gold, zinc, aluminium or silicon. The difference between soft and hard solders is the melting temperature of the soldering material. This temperature is around 350°C.An interesting brief history of solders is given by Vianco and Frear [1]. They report, that in 4000 B.C. solders were already used in Mesopotamia. From archaeoligical evidence those solders were gold-based hard solders.Tin-lead soft solders and their use are not easily found, because in course of time tin has been reduced to stannic acid, making the identification quite difficult. Well preserved soft solder artifacts were discovered in King Tut's tomb dating from 1350 B.C. In ancient time Pb-Sn solders were used primarily for the manufacture and repair of cooking utensils and metal tools. The Romans used lead-tin solders extensively in the construction of the aqueducts."

Jan 1, 1996

By Gordon A. Irons, Diancai Guo

"Uneven movement of scrap during melting in an Electric Arc Furnace causes operation problems: cave-ins interrupt electric power input. The movement also influences the radiation heat loss to water-cooled side panels and roof. An apparatus has been built to simulate the flow of scrap that may be interlocked. It has been observed that flow starts at the point where the suspended length of the pile bottom reaches the average scrap size, and proceeds in the form of cave-ins, but scrap pieces slide with each other as ordinary granules. After a cave-in, the pile angle usually remains much larger than the normally observed angle of repose. The force balance of a partially suspended scrap pile has been analyzed, and the equivalent cohesion due to interlocking estimated. A numerical model has been developed to simulate the scrap flow. Simulated results agree reasonably with observed phenomena.IntroductionWhen one considers the melting of steel scrap in an electric arc furnace (EAF), it is helpful to understand the movement of the material during meltdown. As industrial experience demonstrates, scrap movement greatly affects EAF operation. In a typical operation, scrap is dropped into the furnace from scrap buckets. The roof and electrodes are swung into position, and power is applied to the electrodes situated over the scrap. The electrodes ""bore"" into the scrap by melting into the steel in the immediate vicinity of the electrodes as they are lowered. If solid scrap pieces gradually slide towards the arc area, the electric power supply can be maintained at a high level, with few interruptions or drastic electrode adjustments. This results in a high production rate and low power consumption per tonne of steel produced. On the other hand, if the charge moves down unevenly, i.e. in large surges, usually called cave-ins, the electrodes must be drastically raised, and power supply frequently interrupted. This is also accompanied by a high level of harmonics induced in the power network, deteriorating the quality of electricity supplied to other users.In addition, the movement of scrap in an EAF also influences the furnace heat efficiency, as the scrap pile is much closer to the electric arcs compared to the furnace wall and roof, and absorbs more radiated heat. Early exposure of the wall and roof to the arcs will increase the heat loss due to radiation, and reduce the service life of the furnace."

Jan 1, 2004

By Jiang Diao, Yong Qiao, Xuan Liu, Tao Zhang, Bing Xie

The equilibrium experiments between the FeO-SiO2-MnO-TiO2-V2O3-Cr2O3-MgO slag system and solid pure iron were performed to investigate the vanadium and chromium distribution ratio under Ar atmosphere. The influence of w(FeO), w(V2O3) and w(Cr2O3) in slag on vanadium and chromium distribution ratios were studied at 1653 K. The experimental results were compared with calculated distribution ratios based on molecule and ions coexistence theory. Both of them showed that higher FeO content in slag would improve the distribution ratios of V and Cr between slag and hot metal. The distribution ratio of Cr or V increased with the increase of Cr2O3 or V2O3 content, respectively. To optimize the oxidation of V and Cr from hot metal, a high oxidizing slag and suitable content of Cr2O3 and V2O3 in the slag were recommended. The results provided reference for the further study on the extraction of V and Cr in VTi magnetite.

Jan 1, 2016

By Wei Yin, Bin Xu, Qian Li, Yongbin Yang, Tao Jiang

Copper anode slime is an increasingly significant resource for precious metals such as Au, Ag and Pd. The extraction of Au, Ag and Pd from decopperized anode slime by different pretreatments and different lixiviants including cyanide, chloride, thiourea and thiosulfate have been investigated. When oxidizing roasting pretreatment was carried out under the conditions of roasting time 120min and temperature 625 ℃, the removal ratios of S and Sb could reach 82.18% and 98.52%, respectively. And the following alkaline leaching of calcine could result in the dissolution of 46.40% Cu and 98.48% Pb. The optima leaching ratios of Au, Ag and Pd reached 99.48%, 97.69%, 94.79% by cyanide leaching, and 95.01%, 79.84%, 96.59% by chloride leaching, and about 95.21%, 95.66%, 48.79% by thiourea/thiosulfate leaching.

Jan 1, 2015

By C. D. Chapman

Current regulations regarding the landfill disposal of asbestos containing wastes are inadequate to ensure there are no ground water or airborne emissions. Accordingly, there is growing recognition that asbestos wastes can only be safely disposed of by using techniques that destroy the hazardous fibres. An innovative high-temperature plasma arc technology (The MAGRAM Process) is being developed for the recovery of magnesium metal from asbestos together with supplementary magnesia containing feedstock. The furnace will operate in. open bath mode with aluminium and/or ferrosilicon being employed as reductant. An important advantage of the process is that magnesium vapour within the furnace will be generated close to atmospheric pressure rather than at reduced pressure under which existing processes operate. Thermodynamic modelling work has been undertaken to define the range of slag composition and furnace temperature under which magnesium production at atmospheric pressure is feasible. The effect of slag chemistry, reductant addition, and temperature on product quality and yield have also been investigated and key aspects have been tested on bench scale. A 300 kW pilot plasma furnace unit has been employed for the treatment of calcined asbestos wastes. Aspects of design and operation of the unit are detailed. Acknowledgement: This work is substantially financially supported by the European Communities under the Industrial and Materials Technologies (Brite EuRam H) Research and Development programme.

Jan 1, 1995

By C. W. Won

a-etchant solution is the waste material obtained during the etching by ammoniacal solution of printed circuits for PCs. This material contains a substantial amount of copper (13-14%) but is usually discarded after neutralization. In this work, copper recovery from such solutions by electrowinning or cementation using iron scrap was tested. For each method, the effects of temperature, solution pH, initial copper-ion concentration, and reaction time were investigated to obtain optimal conditions for copper recovery.

Jan 1, 1993

By Corby G. Anderson

Today, with a stringent economic and environmental climate prevailing in the copper business, there is increased interest in evaluating new processing alternatives for production. Hydrometallurgical pressure oxidation of copper concentrates is one of the more viable approaches and several technological candidates have emerged. Of these, an overlooked but, ironically the first industrially proven methodology, utilized nitrogen species catalyzation in the oxidizing pressure leach system to produce copper via SX!EW. Given its many inherent process advantages, this may prove to be a feasible process alternative for the future. In this paper, the history of the system and its application to chalcopyrite concentrates will be outlined. In particular, a novel methodology for effective recovery of precious metals from chalcopyrite concentrates will be discussed. Finally, the perceived economics of this unique industrially proven process will be delineated.

Jan 1, 2000

By D. S. Barr

The Freeport McMoRan chlorination circuit is comprised of four related processes: ore chlorination, gas scrubbing, chlorine supply and excess hypochlorite removal ("hypo kill"). Each of these processes are described, and related to the pertinent mineralogic components in the carbonaceous ore feed to the plant. The chlorination system in use at Jerritt Canyon to passivate forms of preg-robbing organic carbon has proven to be a cost effective and efficient means to recover gold from low sulfide carbonaceous refractory ores, where gold may not be specifically associated with either the sulfides or the carbon.

Jan 1, 1987