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By Vinay Kumar, Jae-Chun Lee, Rakesh Kumar, Manis Kumar Jha, Archana Kumari, Pankaj Choubey

Present work is a part of developing novel recycling technique for waste printed circuit boards (PCBs) i.e. the liberation of metals from PCBs by organic swelling followed by the treatment of resin to remove/ recover hazardous soldering materials. In order to recover the hazardous metallic constituent lead from the liberated resin, initially the leaching studies were made using fresh solder containing 63.9% Pb and remaining tin. Experimental results obtained in different conditions viz. time, temperature and acidity showed -97.20% of lead dissolution with 6M HNO3 at solid to liquid (S:L) ratio 1:10 (g/mL) and temperature 90°C in 75 minutes. The result of the studies validated with crushed PCBs shows that almost total lead and tin was leached out with 6M HNO3 and 6M HC1 respectively at S:L ratio 1:10 (g/mL) and temperature 90°C within 50 minutes. The results will be useful for the treatment and safe disposal of PCBs resin.

Jan 1, 2011

By Xiang Ma, Halvor Dalaker, Kai Tang, Stefan Andersson

Silicon carbide (SiC) is one of the most important non-oxide ceramic materials for many industrial applications and is mainly synthesized by carbothermic reduction of silicon oxide by coke above 2200°C. Replacing natural gas (mostly methane, CH4) for coke in SiC synthesis could considerably reduce energy consumption and CO2-emissions owing to higher carbon activity of CH4 at lower temperature. The generally accepted reaction mechanism is that SiC is synthesized through gaseous intermediate silicon monoxide, SiO. In the present study, the reaction mechanism for the SiO and CH4 gaseous mixture has been examined using atomic scale modelling. Molecular dynamics (MD) using a reactive force field (ReaxFF) has been utilized to examine the initial stages of reactions involving a gas mixture of SiO and CH4 and surfaces of SiC. The MD results revealed some interesting SiC formation mechanisms. The reaction energies of the critical intermediate species were also estimated by density functional theory (DFT) calculations and the implications for the force field parameters used in ReaxFF was discussed.

Jan 1, 2015

By Sun Ying, Zhang Jing, Li Qiu-ju, Wang Yan-ze

Copper smelter slag was leached using sulphuric acid solutions under atmospheric conditions. Base on the composition and phase of copper slag, the effect of the concentration of sulfuric acid and leaching temperature to the leaching growth rate of Fe, Cu, Co and Ni in the copper slag were investigated in this paper. Simultaneously, the influence of sulfuric acid concentration, leaching time, leaching temperature and the amount of sulfuric acid (solid-liquid ratio) to the leaching rate of these metal elements were researched. Experimental results showed that: with the increasing temperature, the dissolution rates of the metals elements increased first and then decreased. Due to the influence of silica gel which was obtained in beginning of leaching, the higher the concentration of sulfuric acid is not conducive to dissolution of the valuable metal elements. The dissolution degree of Fe, Cu, Co and Ni were 92.83% 96.76% 93.62% and 63.41% respectively.

Jan 1, 2016

By Stephan Mulch, Christian His, Patrick M. Stephan, Thibault Champion

"When fuel costs increase dramatically, waste to energy (WTE) conversion technologies become a good alternative to produce energy. The potential energy available in domestic wastes, in developed countries, could be upwards of 4% of their total energy needs. Due to low energy recovery and low level of treated domestic wastes in many countries, the energy coming from waste is generally less than 0.5% of the country needs.Domestic waste incineration can convert heat to electricity for industry and housing and allow waste volume reduction in countries where land fills are a scarce resource.There is a request to improve existing combustion technology by increasing energy recovery with better heat transfer in the boiler and also by increasing lining durability with more resistant materials and technologies.The knowledge of corrosion phenomena and material performance allows Saint-Gobain Group to develop and propose high performance refractory lining solutions.IntroductionThe interest in alternative energy has been growing dramatically in the two last decades due to several combined factors, such as global energy demand, fuels prices evolution (e.g. crude oil, Figure 1) or environmental and geopolitics factors"

Jan 1, 2008

By K. Knuutila

The behaviour of thiourea, animal glue and chloride ions in the electro¬lysis of copper has been investigated by various different electrochemical experiments, i.e. polarization curves with stationary copper electrodes, long-time galvanostatic electrolyses and Hull cell experiments. Polarization curves with stationary copper electrodes show that animal glue has a polarizative effect on the deposition potential. Small thiourea contents affect depolarizatively when high concentrations retard the copper deposition. The microstructures of the deposited copper after the long-time electrolyses show that animal glue favours a basis oriented deposition structure. With thiourea the field orientated structure was evident. It was also observed that the deposited structure depended much on the grain structure of the starter sheet. The chloride ion concentration has a drastic effect on. the crystal size of the deposited copper as it was found out in Hull cell tests. Chloride ions flattened the the crystals and the deposition became smoother when the chloride ions were added. The cathode copper quality is discussed according to the literature. Special attention is paid on the codeposition of thiourea and the origin of sulphur impurities in copper cathodes.

Jan 1, 1987

By Patrick M. Eduafo, Brajendra Mishra, Mark L. Strauss

Direct acid leaching of rare earth metals (REMs) from waste lamp phosphors is non-selective, leading to co-dissolution of impurities mainly calcium, phosphorus, silicon, iron and zinc. Calcining the phosphor powder at different temperatures followed by leaching with HCl isn’t efficient for the extraction of all the chief rare earths especially cerium (Ce), lanthanum (La) and terbium (Tb). Therefore, multi-stage leaching operations are required for the separation of the REMs in phosphor dust. This paper will outline a new process for extracting Ce, La, Tb, Eu and Y from waste fluorescent lamps using a three-stage leaching and separation process. A flowsheet has been developed which shows this process is selective and efficient.

Jan 1, 2015

By Seshadri Seetharuman

The present paper summarises a series of measurements of the interaction parameter of oxygen in liquid copper with respect to a third element, e(M)o, where M is Mn, Zn, As, Se or Te which are common impurities in the liquid metal. The technique employed was the solid electrolyte galvanic cell method. The cell used may be represented as Pt, W or cermet / Cu-O-M // ZrO2 - CaO // AO, A /PT where AO/A represents a suitable oxide/metal reference. The measurements indicate that Mn and Zn interact very strongly with oxygen in liquid copper while, in the case of arsenic the interaction parameter is nearly zero. The behaviour of the elements Se and Te is unique with respect to oxygen interactions in copper bath. At oxygen levels, xo= 10-4 ? 10-5, the apparent interaction parameters are negative, comparable to that for sulphur. On the other hand, at lower oxygen levels, the results indicate that the interaction parameter values are positive. The results are discussed in the light of some of the theoretical models for solute interactions in liquid metals.

Jan 1, 1993

By Lin Yang, Yuanbo Zhang, Zhuoxuan Li, Guanghui Li, Jinghua Zeng, Tao Jiang

A technique has been proposed for recovering iron from hematite-rich diasporic-type bauxite ore in this study. Direct reduction roasting followed by low intensity wet magnetic separation process was carried out. The parameters including reduction temperature and time, sodium salts, grinding conditions and magnetic field intensity for separation of iron were determined. The optimum process parameters as follows: roasting temperature of 1050 oC, time of 60 min, sodium salts involving sodium sulfate, borax, sodium carbonate with dosages of 10 wt%, 2 wt%, 35 wt% respectively, and magnetic field intensity of 1000 Gs with fineness of pulp reached 92.75% passing -0.074mm. Under the optimal conditions, an iron concentrate containing 88.17% total iron grade and iron recovery of 92.51% was obtained, 4.55% total iron grade in tailings. This novel technique provide a potential route for utilizing hematiterich diasporic bauxite ore, recovering iron resource firstly, and extracting alumina from magnetic separation tailings further.

Jan 1, 2015

By Liang Li

Thermodynamic analysis and experiments were conducted in order to verify the feasibility of preparing crude titanium tetrachloride (TiCl4) via the carbochlorination of low-grade titanium slag in molten salt. Titanium slag, assaying 74.6 wt% TiO2 with high calcium and magnesium oxide impurities, was treated by an optimized carbochlorination process in NaCl molten salt. These impurities in the titanium slag were chloridized simultaneously, and chlorination products FeCl2, MnCl2, MgCl2, CaCl2 and CrCl3 were collected in the furnace slag. XRD and SEM/ EDS analysis of residue shown that SiO2 and Al2O3 in titanium slag were difficult to chlorinate completely. Theoretical calculations and industrial-scale experimental studies reveal the content of TiCl4 in the products was more than 98.8 wt% and thus proved the feasibility of utilizing low-grade titanium slag for TiCl4 preparation by molten salt chlorination technology.

By Magnus Ek, Peter Olsson

The Rönnskär Smelter has been faithful to Peirce Smith Converting during its 79 years of existence. Though a visitor to our smelter museum will easily find out that a lot has happened since the beginning – and development continues. In this paper an up-date on Converting and Casting at the Rönnskär Smelter is presented. Recent developments include an investment into converter process gas handling, but also day-to-day operational aspects such as converter aisle productivity and flexibility, but also minimal EH&S impact. 127

Jan 1, 2009

By Alan M. Russell

In recent years, several rare earth intermetallic compounds with the B2-type structure have been reported to exhibit high tensile ductility and high KIC fracture toughness at room temperature. These materials retain considerable ductility even at 77K. These are noteworthy findings because most intermetallics possess poor room temperature ductility and low fracture toughness unless one or more special contrivances are applied (e.g., doping with small additions of interstitial elements, offstoichiometric compositions, testing in ultra-dry atmospheres, etc.). This paper summarizes recent findings on rare earth B2 intermetallics. These include the determination of the active slip systems; the strain rate sensitivities; yield strength maxima at elevated temperatures; the search for possible twinning and stress-induced phase transformations; ab initio calculations of their defect energies and the anisotropy of dislocation line tension. Potential applications of these materials and the possibilities that this study may suggest strategies for increasing ductility in other intermetallic compounds are discussed.

Jan 1, 2008

By Nickolas J. Themelis

Nearly thirty two million tons of municipal solid wastes (MSW) are combusted annually in over one hundred U.S. Waste-to-Energy (WTE) power plants, thus reducing the use of fuel oil by about 1.6 billion gallons of fuel oil One of the advanced WTE processes is the 0.9-million ton/y SEMASS facility at Rochester, Mass. Most of the combustion in the three giant combustion chambers occurs while the injected shredded wastes are in suspension, i.e., in flash combustion mode. The velocity, temperature, and concentration profiles in the SEMASS combustion chamber were simulated by representing the combustible fraction of MSW by the simplified formula C6HIO04 and using the CFD program Fluent to solve the turbulent energy and mass transport equations. After validation against plant data, this model will be used to examine options for increasing the productivity of WTE combustion chambers, such as optimum distribution of primary and secondary air and oxygen enrichment.

Jan 1, 2003

By Nickolas J. Themelis

Nearly thirty two million tons of municipal solid wastes (MSW) are combusted annually in over one hundred U.S. Waste-to-Energy (WTE) power plants, thus reducing the use of fuel oil by about 1.6 billion gallons of fuel oil. One of the advanced WTE processes is the 0.9-million ton/y SEMASS facility at Rochester. Mass. Most of the combustion in the three giant combustion chambers occurs while the injected shredded wastes are in suspension, i.e .? in flash combustion mode. The velocity. temperature, and concentration profiles in the SEMASS combustion chamber were simulated by representing the combustible fraction of MSW by the simplified formula C6HIO04 and using the CFD program Fluent to solve the turbulent energy and mass transport equations. After validation against plant data. this model will be used to examine options for increasing the productivity of WTE combustion chambers, such as optimum distribution of primary and secondary air and oxygen enrichment.

Jan 1, 2003

By Denise Corrêa de Oliveira

Household zinc based batteries, dry and alkaline, has become the most popular sources of electrical energy, and are widely used. Because of their heavy metals content such as mercury, zinc and manganese, spent batteries cannot be directly placed in common landfills without a pretreatment. As a municipal solid waste, these batteries may cause serious health problems and environmental impacts. These damages can be reduced by recovery (which means saving natural sources and energy), recycling and adoption of cleaner technologies. Although this worry has been increasing recently, and producers are doing efforts to reduce the mercury content, batteries still need proper safe disposal conditions or recycling processes. This work presents the efforts in progress to characterize and recycle mixed - dry and alkaline - spent batteries, by using low cost unit operations. Some possible recycling stages and recovery parameters of metals as zinc and manganese are also discussed.

Jan 1, 2001

By O. Forsén

In the first part of this paper is studied the behaviour of small amounts of impurity elements? in the solidification of copper anodes. In the second part the dissolution of these impure anodes in sulphate based electrolysis is discussed. The first part is introduced with practical examples, the .model of solidification of impurities during the solidification of anode copper. According to this model the solidification structures of anode copper are strongly influenced by both thermodynamic and kinetic factors. Thermodynamics determine the microstructure of anode copper, but kinetics can alter the composition of melt to such that there is formed unequilibrium structures during the solidification, especially when the residual melt is solidified. The electrolysis experiments have clarified the behaviour of impuririties in the electrochemical dissolution in sulphate. Based copper electrolysis. In this study it is widely investigated to what extent any impurity elements or oxides will dissolve. In copper electrorefining. With the aid of the electrochemtcal experiments it was possible to fulfil quantitatively the qualitative results accomplished by microstructure studies.

Jan 1, 1985

By Ping Long, Bin Yang, Jian Wu, Xiumin Chen, Wenli Zhang

In this study, the analysis method of trace element in pure indium using glow discharge mass spectrometry (GD-MS) has been established by correcting the analysis result, which was obtained from non-standard quantitative method of GD-MS. The effect of instrument operating parameters, the resolution and isotopes and the pre-sputtering time on the determination results were investigated respectively. The optimized operating parameters of the instrument were obtained as follows: the discharge current was 37.5mA and discharge airflow was 475ml/min. Mass spectral interferences have been eliminated using selected resolution and isotope. The pre-sputtering time was 30 min. 4 trace elements in two pure samples were determined for 6 times. The RSD were less than 20%. The content of trace elements in indium samples was determined by GD-MS and Chemical Analysis Method of Indium which is tested by inductively coupled plasma atomic emission spectrometry, respectively. The results were consistent with each other.

Jan 1, 2016

By V. M. Mukhin

Among the methods proposed for spent activated carbon regeneration, the most acceptable is, thermal reactivation, because in this case the existing equipment for manufacture of activated carbon can be adapted for this purpose. In order to conduct the process of thermal re-activation of spent activated carbon directly at gold mills, a full-scale drum-type furnace with external electric heating has been developed, i.e. EPV-300 model with a throughput rate of 50 to 120 kg/hour. Its use ensures restoration of the adsorption properties of carbon up to the level of fresh activated carbon with an insignificant (by 0.7%) decrease in strength and with a high (95% to 97%) yield of reactivated carbon. During the recent years, activated powder carbon has been extensively used in flotation processes for treating polymetallic ores at ore treating plants to improve recoveries of main metals (copper, lead, nickel, etc.). Especially large volumes of activated powder carbon are used at the Talnakh concentrator of the Norilsk Mining and Metallurgical Complex in Russia for absorption of residual flotation reagents from recycled water in order to ensure efficient selective separation of minerals with similar physical and chemical properties.

Jan 1, 2006

By Osamu Takai, Yoshiki Sato, Nobuhiro Tajima, Hiroyuki Sugimura

"Amorphous carbon thin films doped with nitrogen ( a-C:N) have been synthesized by means of shielded arc ion plating (SAIP). Their electron field emission properties, that is, threshold field strengths for electron emission and maximum emission current densities, were evaluated and compared with those of pure amorphous carbon (a-C) films prepared by the same SAIP apparatus. Among all of the fabricated a-C:N films, the a-C:N films with a N concentration of 23 %, which prepared using Nz arc plasm at a pressure of 1 Pa with applying a sample bias voltage of -100 V, showed the lowest threshold filed of 13.4 V/µm and the highest emission current density of 1.87 µAfcm2 at a field of20 V/µm. These field emission properties of the a-C:N film were much better than those of the a-C films. The best results obtained on the a-C film in this study were the lowest threshold filed of 15.5 V/µm and the highest emission current density of 0.052 µA/cm2 at a field of 20 V /µm. Nitrogen doping to aC was found to be effective for lowering threshold voltage for field emission and for increasing emission current density. The electron field emission characteristics of the a-C:N films depended not only on N concentration but also on chemical bonding state of nitrogen in the a-C:N films. The presence of the ~-C3N4-like phase, which contributes to improve wear resistance of a-C:N as well, distinguished by the NlsXPS peak at 400.5 eV is proved to be crucial in order to enhance field emission properties of a-C:N.IntroductionThere has been much interest in electron field emission from a cold cathode due to its potential applications in vacuum microelectronic devices including field emission displays which are expected as flat panel displays in next generation [l]. It is well known that efficient emission can be rather readily realized using tip-like shape cathodes, e.g., microfabricated three-dimensional electrodes [2], carbon nanotubes [3-5], etc. However, electron emission from planar surfaces is of particular importance since such a type of cathode is· simply fabricated and assembled into microelectronic circuits. Currently, amorphous carbon thin films doped with nitrogen (a-C:N) prepared by plasma processes have attracted attention because their threshold voltages of field emission are relatively low [6]. Among various methods for preparing a-C:N films, the process using arc plasma is of special interest since, in arc plasma, nitrogen is highly activated and new types of carbon nitride phase are expected to be synthesized. However, field emission properties of a-C:N prepared by arc plasma have been studied in less detail compared with that prepared by the other methods such as sputtering."

Jan 1, 2000

By Liangying Wen, Xuewei Lv, Yuelin Qin, Feng Zhu, Guibao Qiu, Chenguang Bai, Meilong Hu, Shengfu Zhang

"The COREX process is the first reduction ironmaking technology with coal and pure oxygen to get high quality hot metal, which consumes a lot of high quality lump coal and some coke. In order to increase the utilization of fine coal, reduce coke consumption and enhance the competitiveness of the technology, the combustion behavior of pulverized coal injection in melter gasifier is studied experimentally. The results show that the combustion rate of PCI increases with the increase of temperature. And the combustion rate increases with decreasing coal particle size. Compared bituminous coal with anthracite, the former’s burning ratio is higher than the latter in the same granularity. The combustion effect is remarkable when coal blend of bituminous coal and anthracite with the smaller particle size is pulverized in COREX process.IntroductionThe COREX process is the first reduction ironmaking technology with raw coal and pure oxygen to get high quality hot metal, which consumes a lot of high quality lump coal [1-3]. However, the proportion of lump coal in raw coal is very small, and it is avoidless to produce fine coal because of mechanical coal cutter and storage and transportation process, so it is important to resolve utilization of fine coal in COREX ironmaking process in order to energy conservation and reduce the cost of hot metal [4]. Currently, Coal briquetting technology is adopted to utilization of fine coal in COREX process [5], but coal briquetting system has high investment cost and requires feasible adhesive agent. The pulverized coal injection (PCI) into a blast furnace is being used on a global scale to improve the stability and reduce the cost of blast furnace operations [6]. The successful development of PCI in blast furnace is contributed to pulverized coal in COREX melter gasifier. However, it is different in PCI process between COREX melter gasifier and blast furnace, and the differences are as follows: firstly, The air is injected into blast furnace, which temperature is about 1200 ?, but in COREX melter gasifier the normal temperature oxygen is blasted, so PCI in blast furnace begin burning in blowpipe, but the combustion of PCI in COREX melter gasifier is only in raceway. Secondly, the racway of COREX is smaller than that of blast furnace of the same size. So, the combustion behavior of PCI is complex in COREX melter gasifier, which is not use for reference."

Jan 1, 2012

By Akira Yazawa

The continuous converting has attractive advantages, but further experimental studies on the slag are required, when the process is considered thermodynamically. The summarized experimental results, obtained with iron silicate slag and with ferrite slag and results relating to actual operation are described and discussed in this paper. At first, equilibrium relations at controlled oxygen potentials among three melts of silica-saturated iron silicate slag, white metal and copper are investigated. The results obtained for slag agreed with the thermo-dynamical predictions. Namely, to suppress a magnetite separation, the system should be at high temperature; in the case of the S02 gas of 10 kPa, for example, magnetite did not separate from the slag at 1300°C, but at 1250 and 1200°C the slag was saturated with magnetite even at lower SO2 pressure. Copper losses caused by dissolution of its oxide increased with increasing 5O2 pressure, and were slightly lower than those reported in previous papers without the matte phase. When the continuous converting slag does not contain any appreciable amount of silica - in contrast to the conventional smelting slag ferrite slag would form, but there was no published fundamental work on-ferrite slags. Hence, the melting behavior and activities of the system CaO-Cu2O-Fe2O3 have been investigated. The liquidus diagram in nitrogen atmosphere was, constructed using both thermal analysis and quenching method. The low liquidus temperature region without magnetite separation was found in the part of low content of Cu2O in the section Cu2O-CaO-Fe2O3 and Cu2O?Fe2O3¬CaO?Fe2O3. The activity of Cu2O in the system was also measured. Slags, composed-of CaO, Cu2O and Fe2O3, in platinum crucibles were equilibrated at 1250°C and controlled oxygen pressures. After quenching, the-composition of slag and platinum crucible were determined qualitatively. On the thermo-dynamic analysis of the results, iso-activity lines were drawn, and it was shown that the slag in the converting furnace of the Mitsubishi process exists in an adequate region of the composition triangle.

Jan 1, 1976