Characterization of Minerals, Metals, and Materials: Materials Extraction
Sponsored by: TMS Extraction and Processing Division, TMS: Materials Characterization Committee
Program Organizers: Shadia Ikhmayies, Al Isra University; Bowen Li, Michigan Technological University; John Carpenter, Los Alamos National Laboratory; Jian Li, CanmetMATERIALS; Jiann-Yang Hwang, Michigan Technological University; Sergio Monteiro, Military Institute of Engineering ; Firrao Donato, Collegio Universitario, Italy; Mingming Zhang, ArcelorMittal Global R&D; Zhiwei Peng, Central South University; Juan P. Escobedo-Diaz, UNSW Australia; Chenguang Bai, Chongqing University; Eren Kalay, METU; Ramasis Goswami, Naval Research Laboratory; Jeongguk Kim, Korea Railroad Research Institute

Thursday 2:00 PM
March 2, 2017
Room: 31B
Location: San Diego Convention Ctr

Session Chair: Zhiwei Peng, Central South University; Bo Lan, Imperial College London

2:00 PM  
Leaching of Copper-Cobalt Tailings from the Democratic Republic of Congo: Yotamu Hara1; Shadreck Chama2; Douglas Mazwi Musowoya2; Golden Kaluba1; Jimmy Machona2; Stephen Parirenyatwa1; Tina Chanda2; Paul Chishimba2; 1Leeds University; 2Copperbelt University
    The investigation focuses on leaching of copper (2 wt.%), cobalt (0.5 wt.%) and iron (2.4 wt.%) from complex tailings material from the Democratic Republic of Congo. The highest recovery of copper and cobalt into the leach solution were 78 % and 10 %, respectively, under direct leaching with sulphuric acid. Higher recoveries (90 % for copper and 96 % for cobalt) were attained when the material was pre-reduced with coal for 1.5 hours in the temperature range of 700 ⁰C – 950 ⁰C. The increased recoveries were due to metallisation of all the copper and cobalt which is in the silicate matrix. The effects of pre-reduction temperature and sample to carbon weight ratios were analysed and found to be important in; (i) achieving high recoveries of copper and cobalt and (ii) decreasing the amount of iron in the leach solution. The samples were characterised by atomic absorption spectroscopy and scanning electron microscopy (SEM) techniques.

2:20 PM  
Optimum Operating Conditions for Extraction of Lignin Precursors from Palm Fruit Bunch: Emmanuel Akpan1; Samson Adeosun2; M. Usman2; 1Ambrose Alli University; 2University of Lagos
    Preliminary studies on the extraction and characterisation of biodegradable lignin from palm oil fruit bunch (POFB) for carbon fibre production has been conducted. Central Composite Design was used to determine the optimum operating conditions for maximum yield and properties of extracted lignin. Soda concentration (1–3 wt./v %), temperature (50–90 0C) and reaction time (20 – 25 min) were analysed using R core. Experimental results show that using reaction temperature of 90 oC, time of 30 min and 3 wt./v % soda concentration yields 3.3 g of lignin from 30 g of the POFB. The path of steepest ascent from ridge analysis shows that with temperature of 130 oC, time of 40 min. and concentration of 3.5 wt./v %, 8.7 g of lignin can be achieved from 30 g of POFB. Analysis of FTIR and SEM show that the lignin has the same structure in all cases with minimal impurities.

2:40 PM  
Experimental Determination of Macro-texture in hcp and Cubic Materials Using Ultrasound: Bo Lan1; Fionn Dunne1; Michael Lowe1; 1Imperial College London
    The authors’ previous theoretical developments have demonstrated that the ultrasonic wave speeds in an hcp or cubic polycrystal aggregate can be represented as the spherical convolution of its single crystal wave speeds and macro-texture, thus enabling detection of bulk texture information from ultrasonic wave measurements. This presentation advances the development by verifying the theories experimentally. An ultrasonic rig, which is based upon a conventional immersion test setup, has been established for the measurement of wave speed variations in plate-shaped samples, and sophisticated signal processing procedures developed to extract the desired texture as pole figures. Tests have been carried out on single-phased materials including commercially pure Ti, zirconium and austenitic steel, and dual-phased Ti-6Al-4V, with results calibrated against those obtained from the well-established neutron diffraction technique. Very good agreements have been achieved, which confirm the validity of the theories and open up possibilities for various applications.

3:00 PM  
Selection on the Process for Enriching Gold from Refractory Gold Ores by Smelting: Weifeng Liu1; Shuai Rao1; 1Central South University
    In order to overcome the shortcomings of traditional cyanidation process for refractory gold ores, the smelting processes have been proposed. These smelting processes could be divided into two kinds, namely, indirect smelting and direct smelting. In the indirect smelting process, the calcine of refractory gold ores are added in the copper or lead smelting processes during which gold can be enriched into copper matte or crude lead. Then gold is extracted from the anode slimes. In the direct smelting process, refractory gold ores are smelted directly with gold enriched into antimony matte or ferrous matte. Then gold is extracted by hydrometallurgical method. Based on the direct smelting process, the metallurgy-beneficiation united process for refractory gold ores has been proposed. In this process, gold is firstly enriched into antimony matte or ferrous matte by direct smelting, then grinding-flotation process is used to obtain gold-rich sulfurous iron ore, and finally gold is extracted via hydrometallurgical method. The metallurgy-beneficiation united process has advantages of high gold recovery ratio, environment-friendly and low cost, it provided a new idea for the extraction of gold from refractory gold ores.

3:20 PM  
Selection on the Process for Removing and Recovering Antimony from Antimonial Refractory Gold Ores: Weifeng Liu1; Shuai Rao1; 1Central South University
    It is well known that the gold ores containing a high content of arsenic and antimony are very refractory. In this paper, the adverse effect of antimony on the extraction of gold by pretreatment-cyanide leaching was discussed in detail. Moreover, these processes of removing and recovering antimony from alkaline sodium sulfide or hydrochloric acid systems were introduced. Last but not the least, a novel cleaning technology for recovering antimony from refractory gold ores was proposed. Antimony was dissolved into the solution with sodium sulfide and sodium hydroxide as leaching agents. And then pressure oxidation technology was applied to prepare sodium pyroantimonate from sodium thioantimonite solutions. This process is more promising owing to its high removal ratio of antimony, low production cost and environment friendly, which provides a positive guidance for the extraction of antimony from antimonial refractory gold ores.

3:40 PM Break

3:55 PM  
Characterization of Spent Printed Circuit Boards from Computers: Zhiwei Peng1; Jiaxing Yan1; Hongjin Zhang1; Xiaolong Lin1; Jiann-Yang Hwang1; Guanghui Li1; Yuanbo Zhang1; Tao Jiang1; 1Central South University
    The pollution caused by the spent printed circuit boards (PCBs) is currently a concern of researchers and environmental managers due to its large quantity and exceptionally complex properties. This study characterized printed circuit boards (PCBs) from discarded computers using a number of characterization techniques, including chemical analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), granulometric analysis and scanning electron microscopy (SEM). The PCBs contain approximately 50 wt.% metals, 25 wt.% glass fibers and 25 wt.% polymers. The principal metals include copper, calcium, tin, aluminum, zinc and lead. They are still wrapped by brominated epoxy resin after the PCBs are preliminarily crushed. As precious metals, such as gold and silver, are barely found in the PCBs, copper and tin are the main metallic elements of recycling value that warrants extra attention.

4:15 PM  
Study of the Effect of the Initial Nucleation Mechanism of Lead Anode Oxidation Film on Internal Stress in Chromic Acid Electrolyte: Yunkai Wang1; Jiangzhong Li1; 1Northeastern University
    Lead substrate anodes are widely used in the electroplating and electrolytic field. Howerver, with the change of internal stress, the oxide films are gradually generated on the surface of lead anode. In this study, electrochemical nucleation of the oxidation film on Pb anode was analyzed with the change of internal stress. Their structure and stress properties were studied during the oxidation by means of Raman spectra, XRD, SEM. The result showed that the diffraction peaks of Pb were mainly found at the initial oxidation stage. With increasing oxidation time, Pb diffraction peaks were weakened and the diffraction peaks of PbCrO4 and PbO/ PbO2 strengthened remarkably. Raman spectra revealed that Raman peaks of PbCrO4 and PbO/ PbO2 were gained in CrO42- ions electrolyte. the electrochemical nucleation type of Pb anode was first instantaneous and then progressive. The Pb alloy anode had a similar eletrochemical nucleation type, but a lower rate.

4:35 PM  
In Situ Observation of the Precipitation of Copper Sulfate Hydrate on the Copper Based Anode Surface: Yuma Ninomiya1; Hideaki Sasaki2; Takeshi Yoshikawa1; Masafumi Maeda1; 1The University of Tokyo; 2Ehime University
    In a copper recycling process, the crude copper containing the large amounts of impurities is generated after smelting the copper scraps. Such low-grade copper cannot be subjected to electrorefining because of anode passivation caused by precipitation of copper sulfate hydrate so that it is refined by a more energy consuming process such as electrowinning. Hence, a fundamental understanding of passivation and preventive method are required to achieve a cost-effective copper recycling process through electrorefining. In this study, the precipitation mechanism of copper sulfate hydrate is investigated with an in situ observation of the copper-based anode surface. It is confirmed that the passivation behavior depends on the growth mode of copper sulfate hydrate.

4:55 PM  
Upgrading of Copper and Cobalt from the Democratic Republic of Congo Tailings: Yotamu Hara1; Shadreck Chama1; Mazwi Doglas Musowoya1; Golden Kaluba1; Jimmy Machona1; Kawunga Nyirenda1; Paul Chishimba1; Stephen Parirenyatwa2; 1Copperbelt University; 2Leeds University
    Our study focuses on upgrading of copper and cobalt from the democratic of the republic of Congo tailings containing 2wt.% Cu and 0.5 wt.% Co. Cobalt is in the complex calcium silicate matrix such that its recovery by direct leaching is not possible. Two concentrating methods were employed in order to obtain copper and cobalt concentrates. Copper was concentrated via flotation and, at the optimal conditions its grade in the concentrate was 32 wt.%. Cobalt was concentrated to 12 wt.% by carbothermically reducing the flotation tailings with coal in temperature range of 800 ⁰C – 1050 ⁰C and followed by magnetic separation. The reaction products were analysed by atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM) techniques. The best carbothermic reduction temperature was found to be 950 ⁰C due to maximum metallisation and less sintering between gangue and metallic/alloy phases.