Min GUO University of Science and Technology Beijing

Transcription

1 Utilization of Zn containing electric arc furnace dust for multi metal doped ferrite with enhanced magnetic property: From hazardous solid waste to green product Min GUO University of Science and Technology Beijing ATHENS th International Conference on Sustainable Solid Waste Management June 2017, Athens, Greece

2 Main content Introduction Experiment and method Results and discussion Conclusions Acknowledgement 2

3 1. Introduction A toxic solid waste Electric furnace steel (EFS) production: Crude steel: 1.6 billion tons (2016, global), EFS 30%; Electric arc furnace dust (EAFD) production: 1-2kg/t EFS, 5-10 million tons/year; Chemical compositions: Fe, Zn, K, Mn, Ca, Pb, Cr, Cd, etc. 3

4 1. Introduction Zn-containing EAFD treatment processes Solidification /stabilization Only for the immobilization of hazardous elements: Cr, Pb, etc. Regardless of recovery of valuable metals (Zn, Fe, K, etc.) High value added utilization for green product? Pyrometallurgy Hydrometallurgy Recover valuable metals (Zn, Fe), pursuing high added value Regardless of the environmental problems 4

5 Research focus: Comprehensive utilization of valuable metals existed in Zn-containing EAFD for high value-added and green product So, prerequisites: 1. Introduction Understand the chemical compositions and major mineralogical phases of the dust 5

6 Chemical compositions (wt%). 1. Introduction Compositions Fe Zn Ca Si Na K Cl Mn Pb Content Compositions Mg Cr As Ba Cd Cu Ni Sb 2- SO 4 Content Major phases: franklinite (ZnFe 2 O 4 ), magnetite (Fe 3 O 4 ) Minor phases: CaCO 3, SiO 2, KCl Fig. 1 (a) XRD pattern and (b) SEM image of the Zn-containing EAFD. 6

7 1. Introduction 1. Stable structure; 2. Excellent chemical, physical stability and electromagnetic property; 3. Great applications as electromagnetic material in: Fig. 2 Unit cell structure of cubic spinel ferrite MFe 2 O 4 (M: Ni, Zn, Mn, Mg, etc.) (1) Electricity (2) Information storage (3) Microwave absorption (4) Ferrofluid (5) Magnetic high density storage (6) Catalysts 7

8 1. Introduction MFe 2 O 4 compositions and structure Compositions and phases of the dust Metal doped ferrite Coexistence of valuable metal By adjusting the components of the dust, the mole ratio of Fe to M (Zn, Mn, Mg etc.) of around 2.0 can be obtained, leading to the one-step synthesis of spinel ferrites from the dust. Fe/M=4.0 (dust) Great applications of Ni-Zn ferrite Addition Ni-containing material (Ni(OH) 2 ) 8

9 2. Experiment and method Fig. 3 General flow diagram for the synthesis of metal doped Ni-Zn ferrite from EAFD 9

10 2. Experiment and method Main focus 1. Mass ratio of Zn-containing EAFD to Ni(OH) 2 (R ZE/N,g g -1 ); 2. Calcination temperature; 3. Toxicity evaluation; 4. Recovery ratio of EAFD. 10

11 3. Results and discussion-r ZE/N Fig. 4 XRD Before patterns washing: of (A) the calcined samples, and (B) the washed samples with After washing: different (Ni,Zn)Fe R ZE/N (a) 2:0.3, (b) 2:0.5, (c) 2:0.7, (d) 2:0.9. (1000 o 2 O 4 2:0.9 C, 2h) (Ni,Zn)Fe 2 O 4 NaCl KCl Metal-doped (Ni,Zn)Fe 2 O 3 Fe 2 O 2 O

12 3. Results and discussion-r ZE/N SEM results (a) blurry edges and corners (b) Octahedron EDS Results Zn,Ni,Ca,Mg,Pb, Si, Cr co-existed in the calcined and washed sample Fig. 5 SEM images and EDS with R ZE/N of 2:0.9 (a) before washing, (b) after washing. (1000 o C, 2h) 12

13 3. Results and discussion-r ZE/N Fig. 6 (a) Room temperature hysteresis loops, (b) variation of the Ms and Ms: improved purity, ions location Hc values of the washed samples with different R ZE/N. (1000 o C, 2h) Hc: anisotropy 13

14 3. Results and discussion-temperature Fig. 7 XRD patterns Before washing: of (A) the calcined samples, and (B) the washed samples under 1000 different calcination (Ni,Zn)Fetemperature (a) 800, (b) 900, (c) 1000 o 2 O o C After washing: 4 C. (R ZE/N =2:0.9, 2h) (Ni,Zn)Fe 2 O 4 NaCl KCl Metal-doped (Ni,Zn)Fe 2 O Fe 4 2 O 3 Fe 2 O 3 14

15 3. Results and discussion-temperature Fig. 8 SEM images of the washed samples with different calcination temperatures (a) 800 oc, (b) 900 oc, (c) 1000 oc. (RZE/N=2:0.9, 2h) Small spherical particles Lager octahedral particles 15

16 3. Results and discussion-temperature Fig. 9 (a) Room temperature hysteresis loops, (b) variation of the Ms and Hc values of the washed samples under different calcination temperatures. (R ZE/N =2:0.9, 2h) Ms: ions doping and ions location Hc: grain size 16

17 3. Results and discussion-temperature Fig. 10 XPS full spectrum and XPS spectra of Cr 2p, Pb 4f, Mn 2p, Fe 2p, Zn 2p, Ni 2p in the metal doped Ni-Zn ferrite. Cr, Pb, Mn, Fe, Zn, Ni, etc. coexisted. The valence states were Cr 3+, Pb 2+, Mn 2+, Fe 3+, Zn 2+, and Ni 2+ 17

18 3. Results and discussion-toxicity evaluation Table Toxicity test results of the Zn-containing EAFD(1), as-synthesized ferrite(2), and metal-doped ferrite(3) according to EN12457 and TCLP standards. EN standard TCLP standard Maximum concentration Cr b.l.d b.l.d. 5 Pb b.l.d. b.l.d. b.l.d b.l.d. b.l.d. 5 Zn b.l.d. b.l.d. b.l.d b.l.d. - Ni b.l.d. b.l.d. b.l.d. 0.4 b.l.d b.l.d. - Cd b.l.d. b.l.d. b.l.d b.l.d. 0.5 Cu b.l.d. b.l.d. b.l.d Ba b.l.d. b.l.d. b.l.d Sb b.l.d. b.l.d. b.l.d As b.l.d. b.l.d Mo b.l.d. b.l.d. b.l.d Hg b.l.d. b.l.d. b.l.d Concentration (mg L -1 ) Zn-containing EAFD: toxic Maximum concentration Se b.l.d. b.l.d. b.l.d F Cl SO 4 Synthesized ferrite: non-toxic

19 3. Results and discussion-recovery ratio Recovery ratio: 87%*85%=74% Fig. 11 Recovery ratio of Zn-containing EAFD during the synthesis process. (1000 o C, 2h) 19

20 4. Conclusions 1.one step solid state reaction method was proposed for the first time to realize the transformation of the dust from toxic solid waste to non-toxic ferrite with a recovery ratio over 70%; 2. The obtained pure metal-doped Ni-Zn ferrite exhibited enhanced magnetic properties with higher Ms (56.8 emu g -1 ) and lower Hc (58.5 Oe); 3. The ferrite was a green product according to TCLP and EN standards. 20

21 5. Acknowledgement This work was financially supported by the National Basic Research Priorities Program of China (No. 2014CB643401, and No. 2013AA032003) The National Natural Science Foundation of China (No , and No ) Professor Mei Zhang Student: Huigang Wang 21

22 Thanks for your attention! Name: Min Guo Institution: University of Science and Technology Beijing E mail: guomin@ustb.edu.cn 22