SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2018, Vol. 26 ›› Issue (3): 583-592.DOI: 10.1016/j.cjche.2017.06.012

• Energy, Resources and Environmental Technology • 上一篇    下一篇

Indirect mineral carbonation of titanium-bearing blast furnace slag coupled with recovery of TiO2 and Al2O3

Lin Wang, Weizao Liu, Jingpeng Hu, Qiang Liu, Hairong Yue, Bin Liang, Guoquan Zhang, Dongmei Luo, Heping Xie, Chun Li   

  1. College of Chemical Engineering, Sichuan University, Chengdu 610065, China
  • 收稿日期:2017-03-27 修回日期:2017-06-19 出版日期:2018-03-28 发布日期:2018-04-18
  • 通讯作者: Chun Li
  • 基金资助:

    Supported by the National Key Projects for Fundamental Research and Development of China (2016YFB0600904).

Indirect mineral carbonation of titanium-bearing blast furnace slag coupled with recovery of TiO2 and Al2O3

Lin Wang, Weizao Liu, Jingpeng Hu, Qiang Liu, Hairong Yue, Bin Liang, Guoquan Zhang, Dongmei Luo, Heping Xie, Chun Li   

  1. College of Chemical Engineering, Sichuan University, Chengdu 610065, China
  • Received:2017-03-27 Revised:2017-06-19 Online:2018-03-28 Published:2018-04-18
  • Contact: Chun Li
  • Supported by:

    Supported by the National Key Projects for Fundamental Research and Development of China (2016YFB0600904).

摘要: Large quantities of CO2 and blast furnace slag are discharged in the iron and steel industry. Mineral carbonation of blast furnace slag can offer substantial CO2 emission reduction and comprehensive utilization of the solid waste. This paper describes a novel route for indirect mineral carbonation of titanium-bearing blast furnace (TBBF) slag, in which the TBBF slag is roasted with recyclable (NH4)2SO4 (AS) at low temperatures and converted into the sulphates of various valuable metals, including calcium, magnesium, aluminium and titanium. High value added Ti-and Al-rich products can be obtained through stepwise precipitation of the leaching solution from the roasted slag. The NH3 produced during the roasting is used to capture CO2 from flue gases. The NH4HCO3 and (NH4)2CO3 thus obtained are used to carbonate the CaSO4-containing leaching residue and MgSO4-rich leaching solution, respectively. In this study, the process parameters and efficiency for the roasting, carbonation and Ti and Al recovery were investigated in detail. The results showed that the sulfation ratios of calcium, magnesium, titanium and aluminium reached 92.6%, 87% and 84.4%, respectively, after roasting at an AS-to-TBBF slag mass ratio of 2:1 and 350℃ for 2 h. The leaching solution was subjected to hydrolysis at 102℃ for 4 h with a Ti hydrolysis ratio of 95.7%and the purity of TiO2 in the calcined hydrolysate reached 98 wt%. 99.7% of aluminium in the Ti-depleted leaching solution was precipitated by using NH3. The carbonation products of Ca and Mg were CaCO3 and (NH4)2Mg(CO3)2·4H2O, respectively. The latter can be decomposed into MgCO3 at 100-200℃ with simultaneous recovery of the NH3 for reuse. In this process, approximately 82.1% of Ca and 84.2% of Mg in the TBBF slag were transformed into stable carbonates and the total CO2 sequestration capacity per ton of TBBF slag reached up to 239.7 kg. The TiO2 obtained can be used directly as an end product, while the Al-rich precipitate and the two carbonation products can act, respectively, as raw materials for electrolytic aluminium, cement and light magnesium carbonate production for the replacement of natural resources.

关键词: Mineral carbonation, CO2 sequestration, Ti-bearing blast furnace slag, Ammonium sulphate, Titanium dioxide, Aluminium oxide

Abstract: Large quantities of CO2 and blast furnace slag are discharged in the iron and steel industry. Mineral carbonation of blast furnace slag can offer substantial CO2 emission reduction and comprehensive utilization of the solid waste. This paper describes a novel route for indirect mineral carbonation of titanium-bearing blast furnace (TBBF) slag, in which the TBBF slag is roasted with recyclable (NH4)2SO4 (AS) at low temperatures and converted into the sulphates of various valuable metals, including calcium, magnesium, aluminium and titanium. High value added Ti-and Al-rich products can be obtained through stepwise precipitation of the leaching solution from the roasted slag. The NH3 produced during the roasting is used to capture CO2 from flue gases. The NH4HCO3 and (NH4)2CO3 thus obtained are used to carbonate the CaSO4-containing leaching residue and MgSO4-rich leaching solution, respectively. In this study, the process parameters and efficiency for the roasting, carbonation and Ti and Al recovery were investigated in detail. The results showed that the sulfation ratios of calcium, magnesium, titanium and aluminium reached 92.6%, 87% and 84.4%, respectively, after roasting at an AS-to-TBBF slag mass ratio of 2:1 and 350℃ for 2 h. The leaching solution was subjected to hydrolysis at 102℃ for 4 h with a Ti hydrolysis ratio of 95.7%and the purity of TiO2 in the calcined hydrolysate reached 98 wt%. 99.7% of aluminium in the Ti-depleted leaching solution was precipitated by using NH3. The carbonation products of Ca and Mg were CaCO3 and (NH4)2Mg(CO3)2·4H2O, respectively. The latter can be decomposed into MgCO3 at 100-200℃ with simultaneous recovery of the NH3 for reuse. In this process, approximately 82.1% of Ca and 84.2% of Mg in the TBBF slag were transformed into stable carbonates and the total CO2 sequestration capacity per ton of TBBF slag reached up to 239.7 kg. The TiO2 obtained can be used directly as an end product, while the Al-rich precipitate and the two carbonation products can act, respectively, as raw materials for electrolytic aluminium, cement and light magnesium carbonate production for the replacement of natural resources.

Key words: Mineral carbonation, CO2 sequestration, Ti-bearing blast furnace slag, Ammonium sulphate, Titanium dioxide, Aluminium oxide