Recycling of Secondary, Byproduct Materials and Energy: Recycling of Ferrous and Non-ferrous Materials
Sponsored by: TMS Extraction and Processing Division, TMS: Recycling and Environmental Technologies Committee
Program Organizers: Mingming Zhang, Baowu Ouyeel Co. Ltd; John Howarter, Purdue University; Elsa Olivetti, Massachusetts Institute of Technology; Alan Luo, Ohio State University; Adam Powell, Worcester Polytechnic Institute; Ziqi Sun, Queensland University of Technology

Monday 2:30 PM
February 24, 2020
Room: 16A
Location: San Diego Convention Ctr

Session Chair: Mingming Zhang, ArcelorMittal; John Howarter, Purdue University; Chengguang Bai, Chongqing University; Mark Strauss, Idaho National Laboratory

2:30 PM Introductory Comments

2:35 PM  Invited
Recycling Research in the Kroll Institute for Extractive Metallurgy: Patrick Taylor¹; ¹Colorado School of Mines
    Researchers in the Kroll Institute have been involved in metals recycling research for the past several decades. This paper presents an overview of some of the recent and current projects and results. This includes recycling of; photovoltaic panels, plasma display panels, hard drives, liquid crystal displays, rare earth magnets; and used circuit boards, as well as impurity removal from automobile shredder steel scrap.

3:00 PM
Recycling of Waste Neodymium Magnet trough Electrorefining of Molten Salt: Xin Lu¹; Xinyuan Zhang¹; Aketagawa Mayu¹; Osamu Takeda¹; Hongmin Zhu¹; ¹Tohoku University
    According to the development of Electric Vehicles, demand for Neodymium (Nd) on neodymium magnets composed of Nd₂Fe₁₄B as a major phase increased rapidly. On the other hand, large amount of neodymium is contained in the waste neodymium magnets, and an efficient recycling of the neodymium from these secondary resources becomes crucial. In this study, recycling of the neodymium magnet wastes through electrorefining in molten chloride to produce Fe-Nd master alloy for the new magnet production was developed. The electrochemical behaviour of Nd³⁺ in the molten chloride salt was firstly investigated. The selective separation of neodymium from the magnet wastes was achieved according to the extremely negative dissolution potential of neodymium (800 ºC: -3.00 V vs Cl₂/Cl^-) less than that of iron and boron. The dissolved Nd³⁺ was efficiently recovered as a Nd-Fe alloy block through the co-deposition electrolysis of Fe²⁺ by continuously introducing Fe²⁺ into the electrolyte.

3:20 PM
Recycling of Metallurgical Slag for Electromagnetic Waves Interference Functions: Yong Fan¹; ¹Institut fur Eisen- und Stahltechnologie
    High-value added application of metallurgical slag and/or dust is a hot research field nowadays because more and more countries begin to pay attention to the recycling. A lot of research has been successful from theory to practise such as the synthesis of cement, ceramics, glass-ceramics, etc. Under this concept, we try to find an alternative application of reusing the slag/dust for electromagnetic waves interference such as absorption and shielding. The special composition and low cost are the advantages with the use of slag/dust for such application. We studied the preparation method and electromagnetic waves interference mechanism to better understand the feasibility of this innovation. This article provides an insight into this topic and lay the foundation of such application.

3:40 PM Break

4:00 PM
Towards 100% Recycling of Steelmaking Offgas Solid Wastes by Reallocating Zinc-bearing Materials: Naiyang Ma¹; ¹Arcelor Mittal
    High zinc concentration in basic oxygen furnace steelmaking offgas solid wastes has been one of the major barriers hindering in-plant recycling of the solid wastes in an integrated steel mill. Therefore, zinc concentration is an important recyclability indicator of the steelmaking offgas solid wastes. In this study, zinc flow analysis was carried out and crucial zinc-bearing materials were identified. After the crucial zinc-bearing materials were reallocated, most of the steelmaking offgas solid wastes became internally recyclable in the sintering – blast furnace ironmaking process for utilization of iron and fluxes. The rest of the steelmaking offgas solid wastes could be recycled internally in the briquetting – basic oxygen furnace steelmaking process for cooling effect and externally in cement industry for iron. As a result, 100% recycling of the steelmaking offgas solid wastes were achieved.

4:20 PM
Extraction and Processing of Crystalline Metallurgical-Grade Silicon prepared from Rice Husk Byproduct: Iyen Cookey¹; Benedict Ayomanor²; Vitalis Mbah²; ¹Federal University Wukari; ²Federal Polytechnic Nasarawa
     Rice husk, an agricultural waste product, could yield valuable silica under controlled temperature and time. Its low production cost makes it most viable for preparing metallurgical grade silicon (MG-Si).In this work, high purity MG-Si ~ 98% has been prepared from rice husk ash (RHA) by extraction. The RHA silica was leached using HNO3 and HCl solutions. Leached RHA was filtered, washed, dried and calcined at 1000oC for 5 h. Further purification was achieved by thoroughly mixing the silica with magnesium powder at a ratio of 1.0g SiO2 to 0.8g Mg, annealed at 1100oC to form magnesium silicide. The material produced was characterized by XRF, XRD and FTIR spectroscopy. Elemental analysis using XRF found percentage of silicon in the material to be 98%, major impurities are Mg (0.96%), Ca (0.08%), Fe (0.2%), K (0.26%), and Al (0.39%). Further analysis using Raman spectroscopy show polycrystalline Si line at 516.6 cm−1.

4:40 PM
A Review of Iron and Steel Scrap Recycling in Ironmaking and Steelmaking Processes: Mingming Zhang¹; ¹ArcelorMittal Global R&D
    The recycling of iron and steel scrap has become an important part of ironmaking and steelmaking industry from both technical and economic aspects. In the past decades the recycling of iron and steel scrap has become more efficient and has included clean scrap generated within downstream industries. Metals recovery systems have also developed for some consumer products (e.g. autos bodies) with recovery rates approaching one hundred percent. Iron and steel scrap recycling from products benefit from increased industry adoption of design for recyclability guidelines by manufacturers. Improved instrumentation and sorting systems enable scrap processors to reduce the degradation of properties and increase the throughput of scrap. Secondary smelters contribute by developing blending technologies that minimize the loss of metal to metallurgical by-products like slag. This paper reviews these efforts of the ironmaking and steelmaking industries to increase reuse and recycling of iron and steel scrap.

5:00 PM  Invited
Low Cost Metal Recovery from E-Waste: Michael Free¹; Prashant Sarswat¹; ¹University of Utah
    The production of electronic waste materials is growing, but the value many recyclers receive for e-waste is limited by costs associated with collection, transportation, device complexity, environmental issues, refining processing fees, and other factors. One key to increasing recycling is increasing the value for recyclers. Low-cost, bio-oxidation driven heap leaching, solvent extraction (or resin for precious metals), and electrowinning to directly extract and recover copper and precious metals from e-waste can potentially provide economic incentive to increase e-waste recycling. This presentation will discuss the opportunities to utilize these low cost technologies and provide results to show the technical viability in extracting and recovering metals such as copper and gold from e-waste.

5:30 PM  Cancelled
Separation and Recovery of Copper from Copper-bearing Pyrite Cinder via an Acid Leaching Process: Yikang Tu¹; Manman Lu¹; Zijian Su¹; Yuanbo Zhang¹; Tao Jiang¹; ¹Central South University
    Pyrite cinder is typical hazardous waste produced from sulfuric acid industry, which contains a significant level of valuable metals, such as iron, copper, cobalt, etc. About 12 million tons of pyrite cinder are generated in China annually, and the utilization rate is less than 50% due to the complex relationship of various components. In this study, a process of acid leaching was used to separate and recover Cu, Co and Fe from the pyrite cinder. The effects of different leaching parameters on the recovery rate of valuable metal in phosphoric acid and sulfuric acid leaching systems were studied. The results showed that the selective separation and recovery effect of iron in the phosphoric acid system is better. The leaching efficiency of copper and cobalt was above 83% and 99%, respectively. 98% of iron were transferred into insoluble FePO4·2H2O, which can be used as precursor of electrode material after purification.

5:50 PM  Cancelled
Granulation and Carbonization Process of Titanium-bearing Blast furnace Slag: Mingrui Yang¹; Gangqiang Fan¹; Feifei Pan¹; Jie Dang¹; Xuewei Lv¹; Chenguang Bai¹; ¹Chongqing University
    Different types of slag during steel making could be produced by different iron ore or with different process. The vanadium-titanium magnetite (VTM) is a special kind of iron ore. The TiO2-bearing blast furnace slag (TBF slag) was produced during the VTM was used as iron ore in blast furnace (BF). The TBF slag contains approximately twenty percent of TiO2, leading to higher melting point and worse fluidity. This type of slag could not be quenched by water as traditional BF slags. It has been develop a process which involves dry granulation and carbonization. The TBF slag was load into a rotation cup, producing the slag particles in a certain range of size under centrifugal force cooling in air. Then the slag particles were reduced and carbonized by methane at 1473K. This process makes better use of sensible heat as well as recovery of Ti element in titanium-bearing BF slags.