Min GUOUniversity of Science and Technology Beijing

guomin@ustb.edu.cn

Utilization of Zn‐containing electric arc furnace dust for multi‐metal doped ferrite with 

enhanced magnetic property: From hazardous solid waste to green product

ATHENS 2017 5th International Conference on Sustainable Solid Waste Management21‐24 June 2017, Athens, Greece

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Main content

• Introduction

• Experiment and method

• Results and discussion

• Conclusions

• Acknowledgement

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1. Introduction

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.

A toxic solid waste

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Zn-containing EAFD

treatment processes

Regardless of the environmental problems

Recover valuable metals (Zn, Fe), pursuing high added value

Regardless of recovery of valuable metals (Zn, Fe, K, etc.)

Only for the immobilization of hazardous elements: Cr, Pb, etc.

PyrometallurgyHydrometallurgy

Solidification/stabilization

High value‐added utilization for green product ？

1. Introduction

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Comprehensive utilization of valuable metals existed in Zn-containing EAFD for

high value-added and green product

Research focus：

Understand the chemical compositions and major mineralogical phases of the dust

So, prerequisites:

1. Introduction

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1. Introduction

Compositions Fe Zn Ca Si Na K Cl Mn Pb Content 37.29 7.79 5.33 2.21 2.78 3.11 2.63 1.18 1.16

Compositions Mg Cr As Ba Cd Cu Ni Sb SO42-

Content 0.72 0.16 0.004 0.050 0.100 0.070 0.012 0.007 2.74

Chemical compositions (wt%).

Major phases: franklinite (ZnFe2O4), magnetite (Fe3O4)

Minor phases: CaCO3, SiO2, KCl

Fig. 1 (a) XRD pattern and (b) SEM image of the Zn-containing EAFD.

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Fig. 2 Unit cell structure of cubic

spinel ferrite MFe2O4 (M: Ni, Zn, Mn, Mg, etc.)

1. Stable structure;2. Excellent chemical, physical

stability and electromagnetic property;

3. Great applications as electromagnetic material in:

(1) Electricity(2) Information storage(3) Microwave absorption(4) Ferrofluid(5) Magnetic high density storage(6) Catalysts

1. Introduction

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MFe2O4 compositions and structure

Compositions and phases of the dust

Coexistence of valuable metal

Metal doped ferrite

Fe/M=4.0 (dust)

Great applications of Ni-Zn ferrite

Addition Ni-containing material(Ni(OH)2)

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.

1. Introduction

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2. Experiment and method

Fig. 3 General flow diagram for the synthesis of metal doped Ni-Zn ferrite from EAFD

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Main focus

1. Mass ratio of Zn-containing

EAFD to Ni(OH)2 (RZE/N, g·g-1);

2. Calcination temperature;

3. Toxicity evaluation;

4. Recovery ratio of EAFD.

2. Experiment and method

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3. Results and discussion-RZE/N

Fig. 4 XRD patterns of (A) the calcined samples, and (B) the washed samples with

different RZE/N (a) 2:0.3, (b) 2:0.5, (c) 2:0.7, (d) 2:0.9. (1000 oC, 2h)

Before washing:(Ni,Zn)Fe2O4

NaCl、KClFe2O3

After washing:(Ni,Zn)Fe2O4

Fe2O3

2:0.9

Metal-doped (Ni,Zn)Fe2O4

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SEM results(a) blurryedges and corners (b) Octahedron

EDS ResultsZn, Ni, Ca, Mg, Pb,Si, Cr co-existed inthe calcined andwashed sample。

Fig. 5 SEM images and EDS with RZE/N of 2:0.9

(a) before washing, (b) after washing. (1000 oC, 2h)

3. Results and discussion-RZE/N

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Fig. 6 (a) Room temperature hysteresis loops, (b) variation of the Ms and

Hc values of the washed samples with different RZE/N. (1000 oC, 2h)Ms: improved purity, ions location

Hc: anisotropy

3. Results and discussion-RZE/N

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3. Results and discussion-Temperature

Fig. 7 XRD patterns of (A) the calcined samples, and (B) the washed samples under

different calcination temperature (a) 800, (b) 900, (c) 1000 oC. (RZE/N=2:0.9, 2h)

Before washing:(Ni,Zn)Fe2O4

NaCl、KClFe2O3

After washing:(Ni,Zn)Fe2O4

Fe2O3

1000 oC

Metal-doped (Ni,Zn)Fe2O4

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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

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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. (RZE/N=2:0.9, 2h)Ms: ions doping and ions location

Hc: grain size

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3. Results and discussion-Temperature

Fig. 10 XPS full spectrum and XPS spectra of Cr 2p, Pb4f, 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 Cr3+, Pb2+, Mn2+, Fe3+, Zn2+, and Ni2+

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Concentration (mg·L-1)

EN 12457 standard TCLP standard

1 2 3 Maximum concentration 1 2 3 Maximum

concentration Cr 9.50 6.34 b.l.d. 0.5 4.81 3.37 b.l.d. 5 Pb b.l.d. b.l.d. b.l.d. 0.5 131 b.l.d. b.l.d. 5 Zn b.l.d. b.l.d. b.l.d. 4 43.9 12.9 b.l.d. - Ni b.l.d. b.l.d. b.l.d. 0.4 b.l.d. 2.34 b.l.d. - Cd b.l.d. b.l.d. b.l.d. 0.04 19.1 0.274 b.l.d. 0.5 Cu b.l.d. b.l.d. b.l.d. 2 - - - - Ba b.l.d. b.l.d. b.l.d. 20 - - - - Sb b.l.d. b.l.d. b.l.d. 0.06 - - - - As 0.651 b.l.d. b.l.d. 0.5 - - - - Mo b.l.d. b.l.d. b.l.d. 0.5 - - - - Hg b.l.d. b.l.d. b.l.d. 0.01 - - - - Se b.l.d. b.l.d. b.l.d. 0.1 - - - - F- 10.6 4.27 2.32 10 - - - - Cl- 2670 3816 24.9 800 - - - -

SO42- 1563 650 333 1000 - - - -

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.

3. Results and discussion-Toxicity evaluation

Zn-containing EAFD: toxic

Synthesized ferrite: non-toxic

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3. Results and discussion-Recovery ratio

Fig. 11 Recovery ratio of Zn-containing EAFD during the synthesis process. (1000 oC, 2h)

Recovery ratio:87%*85%=74%

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4. Conclusions

2. The obtained pure metal-doped Ni-Zn ferrite exhibitedenhanced magnetic properties with higher Ms (56.8emu·g-1) and lower Hc (58.5 Oe);

3. The ferrite was a green product according to TCLPand EN 12457 standards.

1.one step solid state reaction method was proposed forthe first time to realize the transformation of the dustfrom toxic solid waste to non-toxic ferrite with a recoveryratio over 70%;

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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. 51672025, and No. 51372019)

Professor Mei ZhangStudent: Huigang Wang

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Thanks for your attention！

Name: Min GuoInstitution: University of Science and Technology BeijingE‐mail: guomin@ustb.edu.cn