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RECYCLING OF IRON FROM RED MUD BY MAGNETIC SEPARATION AFTER CO-ROASTING
WITH PYRITE
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GROUP MEMBER: M .ANUS 14MN36(G.L)IMRAN 14MN06TANVEER AHMEED 14MN20KHALID HUSSAIN 14MN29TAHIR ALI 14MN60
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OBJECTIVES
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OBJECTIVE
Recycling of Iron from Alumina’s tailing
Make Toxic Red Mud environment friendly
To make the Tailing Profitable
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INTRODUCTION
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WHAT IS RED MUD ? Red mud is a toxic iron rich residue
of Industrial process of Bauxite
Highly Basic pH 10-13
Effects the air,land and water environment of surrounding area
At present,77 Million Tones of red mud is generated annually worldwide
Contain Gibbsite ,Boehmite, Goethite, Hematite (α-Fe203), Anatase and Clay Minerals
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What is RED MUD ? Red mud contain 10-30% hematite
Hematite is being recovered by ‘RED MUD’
Hematite in red mud being transformed into ‘MAGNETITE ’(the highest gade iron ore) with the help of Pyrite
Remaining 2-3% Iron used as ‘REFRACTORY’
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Flow-sheet diagram of recycling of Iron from red mud
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XRD (X-Ray diffraction): for mineralogy & crystallography
XRF (X-Ray Fluorescence): for elemental analysis
TGA (Thermogravimetric Analysis): thermo-analytic technique,works on increasing temprature (heating rate)
TERMINOLOGY
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DTA (Differential Thermal Analysis): thermo-analytic technique,records temprature difference between Sample & Reference
Anaerobic roasting: heated below melting point in absence of air
TERMINOLOGY
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Experiment
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Red mud samples dried at 110 ◦ C for 4 h before testing
30 g of red mud contain the mole ratio of FeS2 to Fe2 O3 was 1:4 or 1:8 roasted at 600 ◦ C for 30 min under N2 atmosphere.
The thermogravimetric analysis (TG) and differential thermal analysis (DTA) of the samples were performed on a thermal analyzer
SAMPLING
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In Fig. the (a)TG-(b)DTA curves showing three weight-loss stages in the range of 500–750 ᵒc
23% of weight-loss
Desulfurization of pyrite at 280ᵒC
Thermo-chemical behavior of pyrite
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TGA-DTA Curves at different mole ratios
The XRD patterns of (a) the anaerobic decomposed residue of pyrite at 700 ◦ C; and (b) the co-roasting product of the above residue with hematite at 600 ◦ C.a=mole ratio of 1:1
b=mole ratio of 1:5c=mole ratio of 1:10d=mole ratio of 1:20
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a= from a Alumina plant in Shanxi,China.b= from a Alumina plant in Henan,China.
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Production process
Red mud samples
Al2O3(%)
SiO2(%)
Fe2O3(%)
TiO2(%)
CaO(%)
Na2O(%)
Sintering Process
1a2b
5.5112.20
4.5920.37
9.78.8
3.813.74
42.3938.00
0.615.76
Bayer’s Process
3a4b
23.2022.36
22.0919.05
13.219.4
6.245.13
18.4013.31
5.648.24
The main chemical compositions of the collected red mud samples
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Co-roasting of Pyrite and Hematite The mixture of hematite and pyrite with
different mole ratios are heated at 500ᵒC for 1h (pyrite decomposes into iron monosulphide FeS)
When the temprature reaches from 525-600ᵒC hematite could be transformed into roasted Magnetite
FeS2 + 4Fe2O3 = 3Fe3O4 + 2S 2S + 12Fe2O3 = 8Fe3O4 + 2SO2
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a=mole ratio of pyrite to hematite in red mud is 1:4
b=mole ratio of pyrite to hematite in red mud is 1:8
Red mud sample no.
Pyrite mixed with 30g red mud
Magnetic part Mass (g)
Magnetic partFe (%)
Non-magnetic partMass (g)
Non-magnetic partFe(%)
11234
0.55a0.28b0.51a0.74a1.10a
3.32.73.04.56.2
36.433.835.236.938.7
24.326.225.022.520.0
1.072.041.190.611.65
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INDUSTRIAL APPLICATION
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1 ton red mud (Fe 15%)+40 kg pyrite is needed to get 232 kg Fe3 O4 upon magnetic separation.
At least 10 kg pyrite is needed to guarantee the transformation, but 167 mol SO2 might be released.
INDUSTRIAL APPLICATION
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CONCLUSION
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Hematite can be transformed into magnetite at 525 ◦ C
The released SO2 used for sulfuric acid production
This method is expected to be applied in industry only if the amount of the pyrite is calculated based on the content of Fe2 O3 in red mud.
CONCLUSIONS
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THANKS FOR YOUR TIME