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By Yasuhiro Konishi, Norizoh Saitoh, Toshiyuki Nomura

This paper describes a new recycling method, based upon biotechnology, in order to extract platinum group metals (PGMs) from post-consumer products. The metal ion-reducing bacterium Shewanella algae was found to exhibit the ability to reduce and deposit PGMs. An integrated bioprocess using Shewanella bacteria to selectively recover Pd, Pt, and Rh from aqua regia leachates of spent automotive catalysts is demonstrated.

Mar 1, 2017

By Wilson Acchar, Fernando Barcelos, Luis Carlos Pereira

"Porous ceramics have been extensively investigated as structural materials for flow of fluids in many applications, such as filters for molten metals, water purification and hot gases, thermal protection systems and heat exchangers. This class of material must have two special features: high permeability and mechanical strength. However, these parameters are influenced in different ways by the processing method and the consequent cellular structure. In this work two different types of commercial ceramic filter materials are investigated. Characterization included the evaluation of the strength values as well as the permeability behavior and microstructural analyzes of the surface fracture. The results indicate that the strength values are strong dependent on the filament defects.IntroductionCeramic materials with a cellular structure have been extensively investigated as structural materials for flow of fluids applications [1-3]. Microstructural aspects such as morphology, size of the cell and the degree of interconnectedness are mainly parameters that influence the properties of these porous materials [4-6]. The most used industrial process to produce cellular ceramics for filter application is the polymeric sponge replication method. This technique consists in dipping the polymer foam into slurry containing an appropriate binder and the necessary ceramic materials, followed by a heating treatment [2,5].Mechanical properties of cellular ceramics depend basically on cell size, degree of interconnectedness and density [1,2,5,8,9]. Materials used as filters required a good strength and also permeability values. These properties are inversely proportional to each other. Higher porosity increases permeability values but decreases the strength values [1,2,5]. The objective of this work is to study the strength resistance of a commercial porous ceramic material (10, 20 and 30 ppi) based on silicon carbide."

Jan 1, 2012

By K. Suseelan Nair

Magnesium alloys containing rare earths are finding increasing applications in space programmes. A number of alloys have been developed and e good data base an the mechanical properties of these alloys is available. However details on metallurgical aspects are found to be sparse in, literature. This paper, at first, briefly reviews the available data on these alloys and subsequently presents the microstructural investigations conducted on quatenary fig-4.9% Zn-1% Rare earth-0.5% Zr cast alley, using optical metallic-graphy, electron probe micro-analysis and X-ray diffraction techniques.

Jan 1, 1989

By G. A. Irons, D. Guo, D. Angheiina

To produce low-carbon (<30 ppm) steel in the tank degassing process, a ladle of steel with an oxidizing slag is placed in a vacuum tank equipped with bottom bubbling. The kinetics of this process are slow compared to the more prevalent RH degassing process, providing the impetus for the present work. There are several aspects to this work: water models of the fluid flow in the ladle; simulation of the decarburization (CO evolution) with C02 desorption in water; pilot-plant (60 kg) studies of the decarburization kinetics; mathematical modelling of the fluid flow in the ladle; mathematical models for each of the kinetic sites (plume, top slag and auto-nucleation); and full-scale trials. The results show that during the refining cycle the contribution from each reaction site changes, suggesting avenues for reducing cycling time and final carbon contents.

Jan 1, 2000

By Jianguo Yin, Wenqiang Yang, Xiaoli Yuan, Juan An, Wentang Xia

Low grade iron ore with phosphorus (LGIOWP), a raw and wasted industrial solid material was used as an adsorbent to remove Pb(II) from wastewater. The effects of initial pH value, adsorptive time, initial Pb(II) concentration, adsorptive temperature and LGIOWP dosage on the Pb(II) removal efficiency were studied. The results show that the Pb(II) removal efficiencies exceed 99.4% and Pb(II) concentrations are less than 0.30 mg/L under the conditions of pH value 7.0, adsorptive temperature 50 oC, adsorptive time 30 min, initial Pb(II) concentration 100 mg/L, particle size <0.25 mm, adsorbent dosage 5 g/L and stirring speed 260 r/min. After Pb(II) removal reaction, the Pb(II) concentrations of wastewater completely accord with the requirement of national discharge standards of pollutants from lead and zinc industries (GB 25466-2010) (TPb= 0.5 mg/L) in China. Therefore, it can be concluded that LGIOWP is a new low-cost adsorbent which is suitable for the adsorption of Pb(II) from wastewater.

Jan 1, 2015

By Jianguo Yin, Xuejiao Zhou, Xiaoyan Xiang, Wenqiang Yang, Xiaoli Yuan, Juan An, Wentang Xia

Low grade phosphorus-containing iron ore (LGPIO), a raw and wasted industrial solid material was used as an adsorbent to remove Cd(II) ion from wastewater. The effects of initial pH value, adsorptive time, initial Cd(II) ion concentration, adsorptive temperature and LGPIO dosage on the Cd(II) ion removal efficiency were studied. The results show that the Cd(II) ion removal efficiencies exceed 99.8% and Cd(II) ion concentrations are less than 0.10 mg/L under the pH value 6, temperature 20 °C, adsorptive time 90 min, initial Cd(II) ion concentration 50 mg/L, particle size <0.15 mm, adsorbent dosage 50 g/L and stirring speed 290 r/min. After Cd(II) ion removal reaction, the Cd(II) ion concentrations completely complies with the requirement of national discharge standard of water pollutants for cadmium and zinc industry (GB 20466-2010) (TCd(II) = 0.1 mg/L) in China. Therefore, it can be concluded that LGPIO is a new low-cost adsorbent which is suitable for the adsorption of Cd(II) ion from wastewater.

Mar 1, 2017

By Shusen Cheng, Kun Yan

An elastic-plastic stress mathematical model of hot blast stove shell has been established in order to investigate the stress distribution and deformation of the shell. The results show that stress concentration happens along the intersection line of hot blast stove body and the hot blast manifold. The plastic deformation occurs on the hot blast outlet in blast period. The deformation degree of the hot blast shell near the blast outlet in blast period is much larger than that in combustion period. In blast period, the shell near the blast outlet elongates along the horizontal direction and shortens along the vertical direction, the shell near the outlet deforms into an oval. And in combustion period, its deformation isn’t obvious. The repeated deformation of the shell near the outlet between different periods may cause the refractory brick damage and be harmful to the long campaign life of hot blast stove.

Mar 1, 2017

By Hong Liang-shi

Olivine lithium iron phosphate (LiFePO4) is considered as one of the most promising materials for lithium-ion secondary batteries because of its high theoretical capacity, low cost, good safety, benign environment and good cycle performance. In this paper, carbon-free and/or carbon-coated olivine lithium iron phosphate composite ultrafine powders were successfully synthesized from aqueous precursor solutions of (NH4)2Fe(SO4)2?6H2O, H3PO4 and LiOH?H2O by co-precipitation method. The obtained LiFePO4 or LiFePO4/C powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Their electrochemical performance was investigated in terms of cycling behavior. As confirmed by X-ray diffraction and scanning electron microscope, the material obtained by co-precipitation within the temperature range of 60ºC to 100ºC and then followed by moderate heat treatment are a single-phase olivine LiFePO4with the particle size of about 300nm. An improved carbon-coated olivine LiFePO4/C material was prepared by adding conductive carbon materials, such as glucose, activated carbon and acetylene black, into the precursor. The carbon dispersed in the materials increases the electronic conductivity of LiFePO4/C composite, and consequently, leads to high rechargeable capacity of the material. The carbon-coated material with carbon amount of 7.64%wt obtained from glucose has the first discharge capacity of 150.3mAh/g at the rate of 0.1C and 129.3mAh/g at the rate of 1.0C, respectively. After cycled for 50 times, the capacity retention rate is 95.13% at the rate of 1.0C in the voltage range of 2.5 to 4.3 V vs. Li/Li+.

Jan 1, 2006

By Denise Crocce Romano Espinosa, Andrea Moura Bemardes, Jorge Alberto Soares Tenorio, Daniella Cardoso Buzzi, Tatiana Scarazzato

"In copper plating processes, a fraction of raw materials are incorporated to the final products, while other portions are discarded as effluents. In this study, the application of electrodialysis (a membrane treatment process) was studied for treatment of wastewaters from cyanide-free strike baths, in order to reuse the components of this bath: copper and HEDP. The synthetic solutions studied consider 1 % of ion concentration of the bath used in this process, simulating the rinsing waters to be discarded. The electrodialysis allowed a percentage extraction up to 73% of copper ions and 72% of HEDP from the effluent. Complexes formation between the acid and copper indicates the possibility of recovery of components in the same compartment, obtaining a concentrated solution of these substances that can be reinserted in the process, for compensating drag-out losses. A diluted solution is also obtained, that can be reused as water in rinsing tanks.IntroductionIn metal finishing industries, contaminants in wastewater and the type of treatment required are determined according to the type of operation [l]. Generally, electroplating industries employ conventional wastewater treatments, e.g. oxidation of cyanide and chemical precipitation. This stage promotes reactions with soluble compounds to produce an insoluble precipitate, removed by physical separation. The sludge is dried by press-type filters [2].In this manufacturing sector, part of the raw materials are discarded as hazardous waste. The cost of discarded compounds and the treatment and disposal of waste may compromise profit margins. In addition, water consumption per unit of production stimulates the development of methods able to recover and reuse the largest possible amount of water [3].In some plating processes, cyanide-based substances are used as complexing agents and as raw materials in form of metal salts [4]. However, the toxicity associated with cyanide has been promoting research for the development of new raw materials in plating processes.A study conducted in Brazil [4] evaluated the modification of a commercial cyanide-free bath for processes of copper coating on Zamak. In the performed study, a new alkaline copper bath was formulated using l,hydroxyethane-1,1-diphosphonic acid (HEDP), an organic compound known for forming stable complexes with metal ions.As results of the study, the operational conditions and the formulation of a bath to obtain adherent, uniform and bright layers were established (Table I) [4]."

Jan 1, 2014

By M. C. Furerstenau

Adsorption behavior of various surfactants on sulfide minerals is very much affected by the nature of the surface of the mineral. Since sulfides are naturally meta-stable, oxidation occurs when they are exposed to air, especially in aqueous environments. As a result. oxygen assumes a major role in sulfide flotation. Mechanisms of adsorption of various thiol collectors on sulfide minerals have been reviewed. The electrochemical behavior of various sulfide minerals has also been reviewed. Flotation behavior of galena, chalcocite, sphalerite, pyrite, chalcopyrite and pentlandite has been presented together with the. flotation of copper sulfide- nickel sulfide ore.

Jan 1, 1993

By Larry B. Fiske

Elimination of dust and processing of fines for both thermal and metallurgical coals is addressed. The efficiency of treatment with lignosulfonates compares favorably to oil in thermal coal. Effect of treatment with various lignosulfonates upon cokability of metallurgical coal was determined by Free Swelling Index, Gieseler Plasticity and Arnu Dilatation.

Jan 1, 1992

By N. Menad

The formation of the dioxins can be dependent on the quantities of carbon, hydrogen, chlorine and oxygen present in a given system, as well as on parameters such as temperature and pressure. Inadequate supply of combustion air ( incomplete oxidation ), low combustion temperatures ( incomplete combustion ), and insufficient turbulence in the combustion are factors which can favour their formation. Dioxins were produced also calatytically from chlorinated phenol precursors, non-chlorinated compounds that were chemically, and reaction of phenol with inorganic chloride. In this paper different precursors such as combination of C, H, 0, Cl, rapid formation/combustion intermediates and routes to PCDFs are reviewed, and the influence of PVC amount on the formation of these isomers is discussed.

Jan 1, 2000

By John O. Marsden

In early 1998, Phelps Dodge embarked upon a program to investigate alternative technology for the extraction and recovery of copper, and other metal values, from copper concentrates. A review of all of the available process alternatives indicated that many were unsuitable for large-scale commercial application and others were clearly targeted at niche applications where contaminants (and consequently smelter penalties) were driving the decision-making. The result of this development program is the world?s first commercial application of high temperature pressure leaching of chalcopyrite concentrate at Bagdad, Arizona, which was commissioned in the second quarter of 2003. Other related processes are in various stages of development. In addition to the obvious considerations, the economic aspects of this technology have been considered in detail at each step in the development of the program. The technology developments in this area are reviewed with emphasis on the economic viability and commercial application.

Jan 1, 2003

By Bing Song, Fei Xi, Xuewei Lv, Kai Zhang

The electric arc furnace process is a common method to produce high TiO2 slag from ilmenite. The pre-reduction process was proposed in recent years in order to reduce electricity consumption. In order to enhance the pre-reduction degree, high energy ball milling was proposed to improve the specific surface area of the ilmenite prior to reduction. In this study, the carbothermic reduction behavior of milled ilmenite concentrate was investigated. It was found that the ball milling method can result in a higher reduction rate and improved metallization of iron. The metallization of iron increased with increasing the time of ball milling. The metallization of iron with milling reached 89.49% when the time of ball milling was 70 min., while the FeO content decreased with 70 min. of milling from 11.84% to 4.76%.

Jan 1, 2014

By S. Mondon

Hibi Smelter which is a Copper Smelter lining a blast furnace, produces 2,700 metric tons of anode copper per month. Generally, in a copper refinery, arsenic and antimony are considerably troublesome impurities. With regard to the elimination of antimony, Hibi Smelter has two handicaps described as follows. (1) Smelting under the slightly oxidizing atmosphere in the blast furnace. (2) Recycling the converter slag to the blast furnace after cooling. Therefore antimony and arsenic, mainly antimony, elimination tests, in which the alkaline flux was injected through the two tuyeres in the blowing stage, were carried out in the rotary anode furnace. Antimony and arsenic were respectively removed more than 90 96 from the molten copper, and their high eliminations are discussed by application of the transitory and permanent reaction model with the flux injection, which was presented by T. Lehner.

Jan 1, 1983

By Zhou Jiemin

In order to fully understand the behavior of the rectangular six- electrode electric smelting furnace and improve its design and operation, a three-dimensional mathematical model has been developed which incorporates the electrical and thermal flows into numerical solutions, assuming a steady state regime. The model has been used to simulate the performance of the 16500 kVA nickel matte smelter at Jinchuan in China, and various factors have been investigated. The results of computation are in agreement with the measured data obtained from this furnace and its physical model. Application of this model is described and the calculation on the Jinchuan smelter shows that the operation expenses can be reduced by optimizing the furnace geometry and some operating parameters.

Jan 1, 1991

By R. Burkhard

Recovery of metals from complex mixed wastes is a challenging task of modem material and waste management strategies. Thermal methods are an important tool in this respect. Plasma turned out to be particularly useful for treatment of complex or toxic wastes and residuals. In order to study plasma processes at reasonable costs, a pilot plasma plant has been used and wastes like ~pent Raney-Nickel catalysts, copper and ah.:lminum drosses, and. other metal containing wastes were investigated. The paper summarizes the most significant findings

Jan 1, 1995

By Johannes Boonstra

High rate bacterial catalyzed processes can serve to improve hydrometallurgical operations. These solutions are not only economical but also environmental sustainable. With references around the globe, the value of this new approach is recognized by industry worldwide. For instance, metals can safely and economically be separated from process and waste streams using biotechnologically produced sulfide, recovering a valuable metal sulfide product instead of a waste gypsum stream for disposal. Both the natural biological sulfur and nitrogen cycles offer bioconversions that are applied on industrial scale. The shared advantage of these processes is that waste compounds are converted in either a reusable raw material or in a harmless product. This way, natural product cycles can be closed. Applications based upon bioconversions are for example: Sulfur based: Bioleaching, reduction of oxidized sulfur compounds to elemental sulfur, metal recovery with biogenic produced H2S, SO2removal from gas streams, etc. Nitrogen based: Ammonia removal using the anammox-process, biological removal of NOxfrom gas streams, nitrate removal from water streams, etc. Metals: Bacterial processes for the reduction of metals such as uranium, selenium and manganese have proven to offer great potential for clean-up of groundwater streams. This paper contains a description of the above applications. Further, a short introduction on engineered high rate bioreactor systems and a description of industrial biotechnological applications will be provided.

Jan 1, 2003

By Neale R. Neelameggham, Brian R. Davis

Organic agriculture is using natural materials such as degrading plant matter to replenish soils. This includes use of naturally degraded plant components such as peat, humus and weathered brown coals. Another important natural organic matter which has not been applied in agriculture thus far has been the black coal, Here we show that reversing the coal formation reaction by combined hydro-oxidation principles of biochemical engineering in natural conversion methods in an accelerated fashion. The modified coal soil additive can convert arid lands into farm lands for the future to sustain the population growth. In addition, the development of this new use of black coal will revive economically deprived areas from phasing out coal in the USA and Europe. This will show how the Stored energy in coal can be made renewable in helping plant growth under the soil to facilitate above ground photosynthesis.

Mar 1, 2018

By Jason Ganley, Yingjia Liu, Adam Dekich, William Tilson, Jeffrey Fergus, Dileep Kumar CJ

"Manganese cobalt spinel oxide coatings have been shown to be effective for preventing chromium volatilization from interconnect alloys, and the associated cathode poisoning, in solid oxide fuel cells. During high temperature exposure a reaction layer consisting of chromium containing spine! forms due to reaction with the chromia scale formed on the alloy. The electrical conductivity of this reaction layer is much lower than that of the coating material and thus can increase the overall area specific resistance (ASR) of the system. The approaches to reducing the ASR are to reduce the thickness and/or increase the electrical conductivity of the reaction layer, which includes both the high-chromium spinel phase and the chromia scale. In this paper the effects of transition metal dopants on the amount and properties of reaction products formed during the reaction of spine! oxide coating materials with chromia are presented.IntroductionThe high cost and difficulties involved with the processing of chromia based ceramic interconnect materials for SOFCs are driving the search for metallic interconnects [1, 2]. The reduction in the operating temperature of SOFC has allowed for the use of high chromium alloy steels for this application [3]. However, the volatilization of chromium from the chromia scale, and the associated poisoning of the cathode, remains a problem which needs to be addressed [ 4]. Though the application of manganese cobalt oxide spine! coatings on the alloy surface substantially reduces chromium poisoning of the cathode [5], the low electrical conductivity of the reaction layer formed between the chromia scale and coating affects the performance of interconnect. Incorporating transition metal ions in the reaction layer could alter the electrical characteristics and improve the performance. Copper and nickel doped manganese oxide spinels are widely used as thermistors due to their high electrical conductivity and negative temperature co-efficient of resistance characteristics [ 6, 7]. Hence doping of copper and nickel in manganese-cobalt spine! oxide composition may improve the electrical characteristics of interaction layer as well and is attempted here."

Jan 1, 2012