Characterization of Minerals, Metals and Materials: Mineral Processing and Analysis I
Sponsored by: TMS Extraction and Processing Division, TMS: Materials Characterization Committee
Program Organizers: Jian Li, CanmetMATERIALS; Mingming Zhang, Baowu Ouyeel Co. Ltd; Bowen Li, Michigan Technological University; Sergio Monteiro, Instituto Militar de Engenharia; Shadia Ikhmayies; Yunus Kalay, Middle East Technical University; Jiann-Yang Hwang, Michigan Technological University; Juan Escobedo-Diaz, University of New South Wales; John Carpenter, Los Alamos National Laboratory; Andrew Brown, Devcom Arl Army Research Office

Monday 2:30 PM
February 24, 2020
Room: 8
Location: San Diego Convention Ctr

Session Chair: Bowen Li, Michigan Technological University; Chenguang Bai, Chongqing University


2:30 PM  
Characterization of Iron Ore Sinter Samples by Automated SEM: Mingming Zhang1; Marcelo Andrade1; 1ArcelorMittal Global R&D
    This paper presents an automatic system for mineralogical and textural characterization of iron ore samples based on a fully automated single scanning electron microscope and point counting analysis. It employs a motorized and computer-controlled multiple sample stage. Mosaic images covering large areas of polished sections are acquired to measure the volume/weight fraction of mineral compositions (phase fraction calculation is based on user-defined density per phase). Different classifiers discriminate compact and non-compact hematite, polycrystalline and monocrystalline particles, and identify particles as granular, lamellar, and lobular. The entire process is automatic and produces a full pdf report containing typical images and the quantification of mineral and textural phases. This study represents an expedient method to prepare well-polished samples and analyze them in a timely manner that can allow for quicker results in process mineralogy.

2:50 PM  
Effect of Pre-Treatment During Leaching of High Iron, Cobalt Containing Ore: Yotamu Hara1; Douglas Musowoya1; Golden Kaluba1; Choolwe Muchindu1; Haggai Simfukwe1; 1Copperbelt University
    Nama Ore contains about 0.3% copper, 0.5% cobalt and 60% iron. Mineralogical examination using scanning electron microscopy (SEM) technique showed that copper and cobalt are chemically dissolved in rich iron matrix and in the heterogenite mineral phase. Direct leaching of this ore result in the following problems; (i) high acid consumption, (ii) high SMBS consumption and (iii) produces sulphur containing leach residue due to the presence of jerosite and, (iv) contaminated leach liquor due to presence of dissolved sodium sulphate. The three problems were overcome by pre-treatment of the ore via carbothermic reduction followed by leaching. The effects of pre-treatment temperature and pH of solution during leaching were determined. Under optimal conditions, recoveries of copper and cobalt of more than 90 %. The leach residue produced by this method is free from sulphur such that it can be used for production of pig iron, thereby lowering the waste disposal problem.

3:10 PM  Cancelled
Effects of Sintering Temperature and Time on Preparation of Refractory Materials from Ferronickel Slag under Microwave Irradiation: Huimin Tang1; Zhiwei Peng1; Foquan Gu1; Lei Yang1; Ziming Liu1; Quanle Leng1; Weiguang Tian1; Mingjun Rao1; Guanghui Li1; Tao Jiang1; 1Central South University
    Ferronickel slag can be used for refractory material production by sintering it with the addition of sintered magnesia in the microwave field. In this study, the influence of microwave sintering temperature and time on the refractoriness and mechanical properties of materials was assessed by contrasting the phase transformations and microstructure changes of samples obtained at different sintering temperatures and time on the premise of fully considering the thermodynamics properties of the raw materials. It was shown that the high quality refractory material with refractoriness over 1750 °C and bulk density over 2.65 g/cm3 was obtained when the sample was sintered at 1300 °C for 20 min. The exploration of sintering temperature and time has good potential in enhancing the quality of refractory material, providing a new approach for the effective and efficient recovery and utilization of ferronickel slag and other related industrial waste.

3:30 PM  Cancelled
Non-isothermal Carbothermic Reduction Kinetics of Calcium Ferrite: Gang Li1; Xuewei Lv1; Xuangeng Zhou1; Guishang Pei1; Guibao Qiu1; 1Chongqing University
    Calcium ferrite is recognized as the ideal bonding phase with superior strength and reducibility in iron ore sintering process. In present study, the reduction behavior of CaO•Fe2O3 with graphite was studied by a non-isothermal method using thermo-gravimetric analysis coupled with mass spectrometry. Flynn-Wall-Ozawa method and Škvára-Šesták method were adopted to analyze the ‘kinetics triplet’ (activation energy, pre-exponential factor, and model function). Results indicated that the reduction process did not start until 1090 K, and the reactions shifted toward higher temperature with an increase of heating rate. The maximum reduction degree of CaO•Fe2O3 could reach 0.93 at 1473 K. X-ray diffraction measurements indicated that CaO•Fe2O3 was reduced to CaO and Fe with four steps (CF→CWF→CW3F→C2F→Fe). The apparent activation energy of CaO•Fe2O3 varied from 543.33 to 753.10 kJ/mol. The reduction of CaO•Fe2O3 can be described by 2-D diffusion model with an integral form of G(α)=[1-(1-α)1/2]2.

3:50 PM Break

4:05 PM  Cancelled
Solid State Reaction Behavior of Calcium Ferrite and TiO2 at Temperature Range of 1423K to 1623K: Mingrui Yang1; Xuangeng Zhou1; Zhongci Liu1; Xuewei Lv1; 1Chongqing University
    The TiO2 was a harmful component in iron ore sintering process and the TiO2 reacted with calcium ferrite to produce perovskite hence decrease the quality of sinter. The solid reaction and diffusion behaviors between the calcium-ferrite based slag and TiO2 were investigated using a diffusion couple method at the temperature range of 1323 to 1473K under air atmosphere. The phase composition and interfacial microstructure were analyzed using the optical microscope, X-Ray diffraction and scanning electron microscope. The concentration gradient of Ca2+ in the diffusion layer and the diffusion of Ca2+ in CaTiO3 was the limited step in diffusion reaction. After diffusion reaction, the interface was serrated and a two-layer structure formed at the interface. The first layer was made up with perovskite, the second layer was made up Fe2O3 and pseudobrookite.

4:25 PM  Cancelled
Gasificating Dephosphorization During the Carbothermic Reduction of Medium Phosphorus Iron Ore Concentrate in Presence of Na2CO3 and SiO2: Jing Zhang1; Guoping Luo1; Yanbiao Chen1; Wenbin Xin1; Jianguo Zhu1; 1Inner Mongolia University of Science and Technology
    To relieve the increasing lacking of high quality iron ore, the medium and high phosphorus refractory mineral resources are being developed worldwide due to the rich storage. The novel method of pre-reducing sinter process was applied to remove phosphorus, characterized by reduced atmosphere, high temperature and negative pressure. For medium phosphorus Bayan Obo iron ore concentrate, effect of carbon mixing ratio, reduction temperature and time on phosphorous gasification and iron metallization during carbothermic reduction was investigated using XRD, FESEM-EDS and FactSage software, in persence of Na2CO3 and SiO2. The optimal carbothermic reduction is conducted at 1050 °C for 60 min with 20 wt% carbon mixing ratio. The corresponding gasificating dephosphorization and iron metallization are 31% and 96%, respectively. Moreover, the further increased carbon mixing ratio and reduction temperature causes the large absorption of reduced phosphorus gas into metallic iron. Notably, the above result provides data support for pre-reducing sinter process.

4:45 PM  
Non-isothermal Reduction Kinetics of Roasted High Alumina Iron Ore Pellets : Zuoliang Zhang; Ren Chen1; 1Liaoning Institute of Science and Technology
    Non-isothermal reduction of roasted Guangxi high alumina iron ore pellets with CO and H2 was conducted with NETZSCH STA 409C/CD. Non-isothermal kinetics analysis was carried out and kinetics data were obtained. The activation energy values of CO and H2 reduction are 295.82kJ∙mol-1, and 185.42kJ∙mol-1, respectively. Their reaction rate constants can be expressed by kCO=1.71*108e(-295820.5/T) and kH2 =1.36*105e(-185422.4/T), respectively. When the temperature is lower than 1357K, the reaction rate constants of the two gases reduction are in good agreement. But when the temperature is higher than 1357K, the level of the reaction rate constant of H2 reduction higher than that of CO reduction increases sharply.

5:05 PM  
Kinetics of Coke Gasification Reaction Catalyzed by Alkali Carbonates: Yunpeng Fang1; Shengfu Zhang1; Cheng Yin1; Yuhan Zhu1; Rongjin Zhu1; Yang Li1; 1Chongqing University
    Coke is the main material of blast furnace(BF), and its reaction speed has an important influence on BF smooth operation. The coke reactivity is mainly affected by coke structure and mineral catalysis. The objective of the present work is to expand the catalytic mechanism of alkali carbonates on coke gasification reaction. Thermogravimetric equipment was used to carry out the non-isothermal analysis experiment and the isothermal analysis experiment. the software (Factsage 6.2) was used to carry out the thermodynamic calculation for gasification of alkali carbonates. Then the interaction of surface activated oxygen species of C6 clusters and alkali carbonates, the adsorption and subsequent desorption behaviors of CO2 on the oxygen vacant surface of Na2O and K2O were systematically studied by using the first-principle method based on density functional theory. The reaction path of carbon-oxygen catalytic gasification was theoretically analyzed to explain the reaction mechanism of catalytic gasification.