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August 2012 JOM Focuses on Sustainability
Posted on: 08/23/2012ALUMINUM: RECYCLING AND ENVIRONMENTAL ISSUES
How materials science and engineering enables progress in environmental sustainability is explored through three robust technical topics in the August 2012 issue of JOM. An overview of technical papers and features supporting this month’s sustainability theme is offered below, with links to this month’s open access articles. To read this JOM issue online, go to Springerlink.
Study on the Mechanical Properties of Cast 6063 Al Alloy using a Mixture of Aluminum-Dross and Green Sand as Mold
S. O. Adeosun, O..I. Sekunowo, S.A. Balogun, and O.O. Obembe
The mechanical characteristics of 6063 aluminium alloy cast in a mixture of aluminium dross and silica sand as mold have been examined. Results obtained demonstrate significant improvement in mechanical properties from 50 to 80 percent dross in the mold. The improvement in mechanical properties by the quench-tempered samples can be attributed to the inducement of fine and coherent Mg2Si crystals within the matrix. Further, the overall analysis of the proportion of dross to the size of cast show that about 64 percent of dross generated can be utilized as mold material.
A Comparison of the Mechanical Properties of Rotary Embossing and Restoration Processes
Hande Güler and R. Özcan
Heat shields are vehicle components that prevent the transfer of the heat that builds up in vehicle components at high temperatures to neighboring elements and the vehicle body. Embossing is a sheet metal forming process for producing bulged designs. After the embossing process, embossed sheets are formed in molds shaped like the vehicle component to be protected from overheating. In this paper, the embossed sheets are compressed with upper and lower rigid platens in a process known as the restoration process. The purpose of this study is to compare the effects of embossing and restoration processes on the yield, tensile, and bending strengths of the sheets.
An Industrial Method for Determining the Amount of Organics in Representative Samples of Aluminum Scrap
Varuzan Kevorkijan, Sreco Davor Skapin, and Urban Dosler
In recycling plants, especially those specialized in the recycling of low-grade aluminium scrap for wrought aluminium alloys, timely and accurately information about the amount of organics and other impurities in the incoming scrap is an important parameter in achieving both economic benefits and standard metallurgical quality of the recycled metal. In this work, an industrial thermogravimetric/differential thermal analysis (TG/DTA) of representative scrap samples was developed as an efficient analytical methodology for analyzing the humidity and organic impurities in incoming scrap. When performed in continuous mode, under a flowing atmosphere of argon with 1 wt. % of oxygen, this methodology enables a routine measurement of the humidity, the quantity of organics, and the carbon content in representative samples of incoming scrap in less than 15 min within an accuracy of ±0.5%.
The Beverage Can in the United States: Achieving a 100% Recycled Aluminum Can through Supply Chain Innovation
The purpose of this research is to analyze why recycled content is low (33-50 percent) in the aluminum can in the United States, when it is technically possible to have a product that is made from 100% recycled material. It is determined that, with respect to aluminum can recycling (and its research), there is a greater focus on the role of the consumer than the producer in the aluminum can supply chain system, which may impact the role of innovation in addressing the problem. The upstream primary aluminum supply chain is vertically integrated and efficient within itself, but not integrated with the downstream secondary aluminum can market.
SOLAR CELL SILICON
Refining of Solar Cell Silicon through Metallurgical Routes
The commentary for this technical topic provides context for the following series of papers that examine by metallurgical routes.
High-Temperature Refining of Metallurgical-Grade Silicon: A Review
Murray D. Johnston, Leili Tafaghodi Khajavi, Mark Li, Samira Sokhanvaran, and Mansoor Barati
This literature review focuses on the main established pyrometallurgical techniques to refine metallurgical grade silicon, including solvent refining, vaporization, electrorefining, and slag treatment.
An Evolving Method for Solar-Grade Silicon Production: Solvent Refining
Takeshi Yoshikawa and Kazuki Morita
This paper examines solvent refining of silicon, focusing primarily on aluminum. The authors provide an overview of the main results and challenges of this refining technique, and highlight the problems that must be addressed in order to improve it.
Removal of Boron in Silicon by H2-H2O Gas Mixtures
Kai Tang, Stefan Andersson, Erlend Nordstrand, and Merete Tangstad
Boron and phosphorous are used as dopants in solar cell silicon and their content in silicon feedstock for PV production must be very low. This paper discusses recent results on boron removal by a water vapor saturated hydrogen mixture and show that 99 percent of boron can be removed from silicon by this technique.
Slag Treatment Followed by Acid Leaching as a Route to Solar-Grade Silicon
Yulia V. Meteleva-Fischer, Yongxiang Yang, Rob Boom, Bert Kraaijveld, and Henk Kuntzel
Slag refining is an established to remove boron from metallurgical silicon. This paper covers an approach of combining slag treatment with subsequent acid leaching to remove most of impurities from the metallurgical grade silicon, proposing a novel refining technique.
The Kinetics of Boron Transfer in Slag Refining of Silicon
Egil Krystad, Kai Tang, and Gabriella Tranell
This paper focuses on the kinetics of boron transfer to the silicate phase during the slag treatment of silicon.
Thermodynamic Calculations for the De-Phosphorization of Silicon using Molten Slag
In-Ho Jung and Yumin Zhang
In this study, the thermodynamic assessment of Si-P system was carried out, and then the de-phosphorization reaction equilibria between molten Si and CaO-based slags were calculated using the thermodynamic databases for Si alloy and slags. The thermodynamic calculations show that dephosphorization of Si under oxidizing condition (in the form of phosphate) merely
happens and the de-phosphorization under reducing condition (in the form of phosphate) can cause the significant dissolution of Ca in molten Si.
WASTE HEAT RECOVERY
Waste Heat Recovery from Metal Industries
This introduction to the following JOM technical papers on waste heat recovery in the production of metals also provides a brief review of the current state of this technical area.
The Autoignition of Cyclopentane in an Ignition Quality Tester
Donna Post Guillen
Cyclopentane is a flammable hydrocarbon being considered as a working fluid for waste heat recovery applications using Organic Rankine Cycles with direct evaporators. A postulated failure mode consisting of a pinhole leak in a heat exchanger tube raises safety concerns because of autoignition of the working fluid. The ignition delay time of cyclopentane was measured using an Ignition Quality Test™ device. For the cases tested, no ignition was observed at temperatures at or below 723 K or at an equivalence ratio of 0.5.
An Overview of Opportunities for Waste Heat Recovery and Thermal Integration in the Primary Aluminum Industry
Cassandre Nowicki and Louis Gosselin
Efficient smelters currently consume roughly 13 MWh of electricity per ton of aluminum, while roughly half of that energy is lost as thermal waste. Although waste heat is abundant, current thermal integration in primary aluminum facilities remains limited. This paper presents a mapping of both heat dissipation processes and heat demands around a sample facility (Alcoa Deschambault Quebec (ADQ) smelter). The primary aim is to report opportunities for heat recovery and integration in the primary aluminum industry.
Waste Heat Recovery from Blast Furnace Slag by Chemical Reactions
Yuelin Qin, Xuewei Lv, Chenguang Bai, Guibao Qui, and Pan Chen
Blast furnace (BF) slag, is the main by-product in the ironmaking process, which contains large amounts of sensible heat. To recover the sensible heat, a new waste heat recovery system—granulating molten BF slag by rotary multi-nozzles cup atomizer (RMCA) and pyrolyzing printed circuited board (PCB) with obtained hot BF slag particle, was proposed in this study. The results showed that it is primarily feasible. The obtained slag particle is amorphous and spherical by RMCA method. The energy of hot BF slag could be converted to chemical energy through the pyrolysis reaction and a large amount of combustible gas like CO, H2, CmHn, and CH4 can be generated during the process.
Energy Conservation for Granular Coal Injection into the Blast Furnace
Hongwei Guo, Buxin Su, Jianliang Zhang, Jiugang Shao, Haibin Zuo, and Shan Ren
Injection characteristics of granular coal were studied through proximate analysis, element analysis, and research of ignition point, meltability of ash, grindability, and calorific value. Utilization ratio and energy efficiency of granular coal used in the blast furnace are discussed, offering theoretical foundation and technical support for intensifying granular coal combustion and promoting granular coal injection.
Combustion-supporting Effect of Common Carbonous Solid Waste on Anthracites
Jianliang Zhang, Shan Ren, Zhengjian Liu, Yue Zhou, Fanyi Meng, and Buxin Su
In order to study combustion characteristics of anthracite with additives, the influence of common Carbonous Solid Waste (CSW) on anthracite is studied by thermogravimetry. The results show that appropriate CSW additives mixed with Pulverized Coal (PC) in PZH Steel can promote the combustion of PC, and increase the burning ratio of anthracite greatly.
A Hothouse of Great, Green Ideas
This article examines the many materials issues and considerations involved with taking on the Living Building Challenge, which goes beyond Leed Platinum standards of efficiency to require that a structure prove net-zero energy balance and net-zero water useage, as well as deployment of sustainable, toxin-free materials. Illustrating this process is an overview of the integrative design process used by Phipps Conservatory and Botanical Gardens in its quest to have its new Center for Sustainable Landscapes be certified as one of the first buildings in the world to meet the Challenge.