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By Li Zhang

Air was blown into the molten slag as oxygen resource during the dynamic oxidation. It was found that the oxidation is not only in favour of Ti components into perovskite phase, but also the increase of slag temperature and decrease of slag viscosity during the dynamic oxidation promote the precipitation and growth of perovskite phase, average crystal size of perovskite phase is 48 µm. The experimental result realizes the selective enrichment of Ti components and coarsening of perovskite phase, perovskite phase can be separated by mineral dressing method.

Jan 1, 2009

By Fang Wu

The paper designs an extraction flow for the total recovery of nickel and cobalt and removing magnesium simultaneously from the cadthodic materials of the spent hydrogen-nickel and cadmium-nickel batteries. The separation of Co, Ni and Mg though P507 extraction .The extraction equilibrium pH is 4.5~5.0, ßNi/Co is 140~180, and ß Ni/Mg is 20~25; nickel and magnesium are scrubbed in two steps, in which the equilibrium pH of nickel and magnesium scrubbing is controlled at 5.0±0.1 and 4.4±0.1 respectively. The stepwise scrubbing technique is adopted to remove 94.5% of magnesium and to recover 99.45% of nickel and 95.35% of cobalt. During the integrated extraction and precipitation process the total recovery fraction of nickel and cobalt are 99.99% and 99.95%, and the recovery fraction of magnesium is 94.02%.The recovered NiSO4 and CoSO4 solution are enriched and crystallized.

Jan 1, 2009

By Patricia Martínez Nicolás

Nickel and ferronickel are some of the major components in the production of special alloys; however, the energy consumption for their production greatly increases their price. A cheaper option could be to use NiO and a reducing agent. This work presents experimental and theoretical analysis to estimate the effect of slag basicity and amount of reducing agents on the NiO reduction from the slag which interacted with molten steel at 1600 °C in an EAF. The slag system contained CaO, SiO2, CaF2 and NiO together with a reducing agent, ferrosilicon or carbon. The NiO content in the slag was 25 mass%. The amounts of the reducing agents (Si and C) were 1 to 4 times the stoichiometric mass to reduce NiO. The CaO/SiO2 ratio was 1.5 and 2.5. The kinetics of the process was very fast since after few minutes the maximum nickel yield was obtained. The slag basicity had a negligible effect on the reduction of NiO.

Jan 1, 2006

By Andrew Wessman

Keywords: Recycling, Electrodeposition, Recovery, Dilute, Dissolved Metal Ions In order to facilitate the recovery of pure metals from solutions containing a mixture of dissolved metal ions, a pulsed electrodeposition method was developed. Using this method, it is possible to selectively remove metal ions from solution based upon the electrochemical potential of the particular ion desired. The use of pulsed electrodeposition rather than direct current electrodeposition creates an electrodeposited material with better morphology, increases electrical efficiency of the process, and avoids problems with short circuiting between electrodes. Using this method, it is possible to recover dissolved metal ions in a purified form in one simple step, and therefore maximizes recovery of the metal ions while obtaining them in a saleable form. This method is likely to be useful in improving the recycling process for numerous complex metal mixtures and alloys.

Jan 1, 2005

By Jian Yang

The mechanism of resulfurization in the desulfurization process with magnesium vapor produced in situ by aluminothermic reduction of magnesium oxide was clarified in the present work. The influences of various operating parameters on the resulfurization were studied and the methods that could prevent resulfurization were proposed. There are two kinds of mechanisms of resulfurization in the desulfurization process with magnesium. One is decomposition of the desulfurization product of MgS under the inert atmosphere. The other is oxidation of MgS under the oxidative atmosphere. Under the present experimental conditions, lowering operating temperature and oxygen partial pressure in the atmosphere could effectively prevent the resulfurization. Adding CaO onto the melt surface was an effective method for preventing the resulfurization due to transformation of the desulfurization product of MgS into the more stable compound of CaS. Since addition of the activated charcoal powders greatly decreased the transfer rate of oxygen in the atmosphere to the melt surface, it also reduced the resulfurization remarkably.

Jan 1, 2006

By Wenming Wang

Recycling of retired cadmium telluride (CdTe) photovoltaic (PV) modules has attracted attention due to new European environmental regulations. Recycling tellurium from CdTe PV modules is becoming more important because of the low availability of this metal. We investigated several treatment paths for reclaiming tellurium from solutions obtained from leaching fragments of CdTe PV modules. Our experiments showed that conventional soda ash neutralization/hydrolysis methods recovered only 50~60% of tellurium. However, by appropriately combining neutralization and sulfide precipitation, almost all the tellurium present in the leaching solution was precipitated and recovered; the concentration of tellurium in the processed solution was reduced from 900-1000 mg/L to less than 1 mg/L, yielding a tellurium recovery greater than 99%. This method can be incorporated in the scheme of recycling spent CdTe PV modules and manufacturing wastes. It may be also an alternative to the current operations for removing tellurium from copper anode slime leaching solutions.

Jan 1, 2006

By Jukka Tuominen

The history of making blister copper in an Outokumpu Flash Smelting Furnace dates back to the late 1960?s, when Outokumpu first piloted the Outokumpu Direct Blister (ODB) process. The first commercial scale applications have been in use at Glogow, Poland, since 1978 and at Olympic Dam, Australia, since 1988. These applications utilize special concentrates, which are low in iron, and thus the formation of slag is also low. In 1995 the same principle was applied to smelting copper matte into blister copper in industrial scale at Kennecott Utah Copper. This application, the Kennecott-Outokumpu Flash Converting process, will celebrate its 10th anniversary of commercial scale operation this year. This paper outlines the development in efficiency and flexibility of Blister Flash Smelting processes compared to other smelting and converting options. The focus is on the economical aspects i.e. on the total feasibility of both greenfield investment projects and revamping of existing smelters.

Jan 1, 2005

By Javier Enrique Basurco Cayllahua

In this work, a gram-positive bacteria was used as biosorbent to elucidate the aluminum load capacity under different conditions related to metallurgical and chemical plants. The sorption data followed the Langmuir, Freundlich, Dubinin-Radushkevich isotherms. In order to determine the best isotherm fit, three error analysis methods were used to assess the data: correlation coefficient (R2), residual root mean square error (RMSE) and Chi-square test. The error analysis established that the Dubinin-Radushkevich model fits better the aluminum biosorption data. The maximum sorption capacity was found to be 41.59 mg.g-1. The maximum removal of aluminum was 95% at pH around 5. The experimental kinetics data was evaluated considering two models (pseudo-second order and pseudo-first order). This study indicated that the R. opacus is an environmental friendly biosorbent.

Jan 1, 2009

By He De-wen

The municipal solid waste is a by-product of the daily life of urban residents. The quantity and ingredients of municipal solid waste has exceeded the current management and disposal ability, which has done a great harm to municipal environment and sanitation quality and threatened people?s health. On the basic of analysis on the amounts and main elements of municipal solid waste of Changsha City, the sanitation landfill, incineration, composting, reclamation and utilization technology of household waste were compared specifically in this paper. Based on the concrete conditions of Changsha City, the paper has proposed a disposal proposal combined with reclamation and landfill of municipal solid waste of Changsha City, and the environmental benefit, social benefit and economical benefit of the prepared processing routes were also analyzed in the paper.

Jan 1, 2009

By Jesús Contreras

Within its programme for continuous improvement and cultural change, Atlantic Copper has installed the Six Sigma methodology as a basic tool for the improvement of management techniques in all its production centres. Following an implementation period, the methodology is widely used for analysis and improvement, not only in the fields of production and maintenance, but also in other areas of the business such as supplies or energy management. The present paper describes, phase-by-phase, the project that was developed to improve the quality of converter slag through the application of Six Sigma techniques, from the initial set up to the final results obtained.

Jan 1, 2005

By Masaki Imamura

A novel hydrometallurgical process for copper concentrate treatment has been developed by Niihama Research Laboratories of Sumitomo Metal Mining Co., Ltd. The process has numerous advantages with respect to the operational and environmental aspects. For example, copper is leached effectively from chalcopyrite concentrates by chlorine gas under atmospheric pressure. The copper in the leach solution is then separated from iron and silver by solvent extraction and undergoes electrowinning for its recovery as a highly pure copper metal; this does not require any further purification. Moreover, iron metal can be produced from the purified raffinate by electrowinning without generating a large volume of goethite or hematite, which are solid wastes generated due to iron rejection in common hydrometallurgical processes. This process can also realize the efficient recovery of precious metals. The results of batch testing and continuous-operation testing are presented in this paper.

Jan 1, 2006

By Wolfgang Van Hooff

Encouraged by a strongly growing and evolving market for granulated products, Paul Wurth continuously improves its granulation and dewatering technologies to provide customers with state of the art installations. Continuously developed know-how about the granulation process of iron blast furnace slag enabled application to non-ferrous materials such as Ni-Slag, Pb-Slag, Blister Copper, Cu-Matte and even TiO2-Slag, which rank among the most difficult materials to granulate. This paper identifies how critical objectives in granulation and dewatering technologies applied to different molten materials with respect to various product quality objectives can be addressed. The differences between hot and cold water granulation systems are explained, including the step from cold runner to granulation water tank. Development of a flow and pressure controlled blowing box is the latest step to optimize the granulation process in order to meet the latest standards in terms of quality, power consumption and environmental protection.

Jan 1, 2006

By Vincent Menard

The purpose of the present work is to demonstrate the removal of manganese from a neutral leach zinc-rich solution ([Zn] =150 g/L) at 80°C by oxidative precipitation using a gas mixture of sulphur dioxide (SO2) and oxygen (O2). In order to determine the optimum conditions for manganese removal, several bench-scale semi-batch experiments were performed, where the effects of ORP and gas mixing were investigated. These tests showed that SO2/O2 is a fast and effective oxidant for removing manganese down to ppm level as long as the appropriate ORP is attained/maintained and gas transfer kinetics are optimized.

Jan 1, 2006

By Eun-young Kim

Electrogenerated chlorine leaching of waste printed circuit boards was investigated in hydrochloric acid solutions. The pulverized printed circuit board contained about 37.6% of metal component, in which copper was about 83.6%. The leaching rate of copper was greatly affected by current density and agitation speed. The leaching of copper up to 98% was achieved at 20 mA/cm2, 50?, 180 minutes, and 600 rpm in 1M HCl solution. Increasing agitation and lowering current density enhanced utilization efficiency of electrogenerated chlorine. Leaching of copper was suppressed at initial stage, while the minor metal elements, such as aluminum, lead, and tin, were dominantly leached out.

Jan 1, 2006

By Zhigang Liang

A carbon free precast block was prepared by using high-alumina fused corundum as aggregate and fused magnesia, and ultra-fine Al2O3 and ultra-fine SiO2 powders as matrix materials. A small linear expansion for the precast block was achieved through spinel formation from the reaction of MgO with Al2O3. The precast block showed a lower apparent porosity, higher hot modulus of rupture and better slag corrosion resistance compared to the traditional Al2O3-MgO-C brick. Moreover, the practical application of the precast block to the ladle lining proved it to possess a better thermal insulation which could effectively prevent the temperature drop of molten steel during the refining process. It can be predicted that the carbon free precast block could possibly be accepted as a new type of ladle lining material for the production of low-carbon and ultra-low-carbon steel.

Jan 1, 2009

By He De-wen

The influence of wastewater containing benzene from chemical industry by technology combined blow-off with Fenton reagent oxidation was experimentally studied. The present results suggest that the technology combined blow-off with Fenton reagent oxidation can effectively remove benzene pollutant in wastewater. The main factors that influence the removal benzene such as temperature and blowing time and volume, pH and reagent dosage of H2O2 and Fe2+ are studied and the optimal experimental conditions are as follows: time 20min, temperature 40i, air-blowing volume 0.4L/min, pH value 5, and H2O2 and Fe2+ dosage 2mL/L and 200mg/L respectively. Under the above conditions, benzene pollutant can be removed up to 97%. Compared to other removal ways of wastewater containing benzene, the technology combined blow-off with Fenton reagent oxidation is more effective and has the advantage of high speed.

Jan 1, 2009

By Xiaowen Liu

The thermal decomposition of diaspore was investigated by thermogravimetry (TG),differential scanning calorimetry (DSC), X-ray power diffraction(XRD),infrared (IR)spectrain this paper. The thermal decomposition mechanism of diaspore was discussed according to Coat-Redfer equation. It was found that the decomposition of diaspore was carried out at 500?,and the peak temperature was 530?. The electrovalent balance of diaspore was destroyed. The previous crystal structure was changed. a- Al2O3 was obtained after thermal decomposition. The activation energy is 287KJ/mol.

Jan 1, 2006

By Guo Xueyi

The method of Substance Flow Analysis (abbreviated as SFA) provides a helpful tool for the study of the industrial metabolism of a certain metal within a regional level. In this work the flow of lead in China, 2006, was traced within the STAF model, and the situation of production, consumption and recycling of lead resources in China were introduced. The SFA is performed on lead flows during its one year life cycle in detail. As one of the biggest producer and consumer of lead in the world, China is facing a problem depletion of lead resources. How to increase the resource efficiency is a significant issue for lead industry of China. Based on the result, several suggestions were proposed in the paper, aiming to contribute important reference information for the industrial metabolism and resource management and recycling of lead industry in China.

Jan 1, 2009

By Zhao-feng Xie

A new process of recycling valuable metals containing in the slag of jamesonite smelting in the blast furnace was studied. In this process, the valuable metals such as Pb, Sb, Zn and In etc. were fumed and volatilized and enriched in the dust firstly and then the dust was leached by sulfuric acid. In the leaching procedure, Zn and In in the dust entered into the leaching solution and were separated from Pb and Sb which remained in the residue.The optimal operation conditions of the fuming procedure are as follows: the mass ratio of the blast furnace slag, coal powder and lime are 100:22:10 respectively and the fuming time are 1.5~2.5 h, the fuming temperature is not below 1200C and the volatilization rates of Pb, Sb, Zn and In are 95%, 92%, 86% and 75% respectively. The optimal conditions for the leaching procedure are also presented: the consumption of sulfuric acid is 1.15 times of the theoretical consumption, the ratio of liquid to solid is 4:1 and the leaching temperature, leaching -1time and stirring speed are 90, 1.5h and 300 r?min separately. The leaching rates of Zn and In are 98.5% and 95.2% respectively. The experimental results shows that the valuable metals in the dust can be recovered and separated effectively by this process and the?ir recovery efficiencies are as follows: Pb94%,Sb91%, Zn84% and In69%.

Jan 1, 2009

By N. E. Idenyi

The effects of compositions and firing temperatures on the physico-mechanical properties of blended Nsu fireclay and Nkalaha redbrick clay have been investigated. The clay samples were compounded according to the following ratios: 10:90, 20:80, 30:70, 40:60 50:50, 60:40, 70:30, 80:20 and 90:10 in the order Nsu: Nkalaha respectively, and test samples made and fired at 9000C, 10000C 11000C and 12000C. The properties tested for were the modulus of rupture, porosity, shrinkage, apparent density, water absorption and bulk density. From the results obtained, it is inferred that the blends have a maximum service temperature of 11000C, with the 30: 70 blend presenting the best characteristics. A conclusion is drawn to the effect that the blend could be adapted for the production of ceramic earthenware, electrical porcelain pin insulators, cement manufacture and for refractory linings where temperature requirements are less severe.

Jan 1, 2006