Direct reduction of copper slag-carbon composite pellets by coal and biochar.
Autor: Zuo, Zongliang; Yu, Qingbo; Xie, Huaqing; Yang, Fan; Han, Zhicheng; Qin, Qin
Publication year: 2020
Environmental technology
issn:1479-487X 0959-3330
doi: 10.1080/09593330.2018.1561757
Abstract:
As a renewable resource of reducer, biochar prepared by pine sawdust is proposed for direct reduction of copper slag in this paper. Combined with thermodynamic analysis, effects of reduction time, temperature and CaO addition ratio on solid copper slag reduction characteristics are discussed. The oxides of iron in copper slag are Fe(3)O(4) and 2FeO·SiO(2). The reduction processes were carried out step by step for Fe(3)O(4) and 2FeO·SiO(2), respectively: Fe(3)O(4 )→ FeO → Fe and 2FeO·SiO(2 )→ Fe. The porous structure of biochar exhibits higher reduction reactivity and reaction rate than that of coal. CaO reduced the Gibbs free energy of reduction reactions and facilitated the reduction of 2FeO·SiO(2) with C and CO. When CaO was added, separation reaction of FeO and SiO(2) took place and α-SiO(2) and β-SiO(2) were produced. When the addition ratio of CaO is above 0.3, CaO·SiO(2) and 2CaO·SiO(2) are produced. The reduction process of copper slag was established as follows: (a) dehydration and fast pyrolysis; (b) reduction of iron oxides by C and CO; and (c) sweating metallic iron outflows from cracks in pellet. Besides, direct reduction reaction mechanism and transport process of Cu are established based on reduction experiments, XRD and SEM-EDS analysis.
Language: eng
Rights:
Pmid: 30582415
Tags: *Coal; *Copper; biochar; Carbon; Charcoal; composite pellet; Copper slag; direct reduction; Silicon Dioxide; thermodynamic analysis
Link: https://pubmed.ncbi.nlm.nih.gov/30582415/
