1864 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
of the particles. Ultimately, a tiny amount of wüstite was
unable to be reduced.
CONCLUSIONS
This study proposed a fluidized hydrogen reduction tech-
nology to treat boron-bearing iron concentrate. The effects
of the reduction conditions on the metallization degree
and the mineral phase composition of the reduced prod-
ucts were investigated, and the formation and structural
evolution of metallic iron during the fluidized reduction
process were discussed in detail. The main conclusions were
as follows:
(1) At 500–550 °C, magnetite was reduced directly to
porous metallic iron by hydrogen. Above 600 °C, the reac-
tion path was magnetite → wüstite → metallic iron, and
the wüstite was surrounded by a dense iron layer, which
hindered the direct contact and reaction between hydrogen
and iron oxide, resulting in a significant drop in the metal-
lization degree at 600–650 °C.
(2) The reduction behavior of ludwigite was observed
for the first time. When the reduction temperature was
700 °C, the structure of ludwigite was stable and could
not be reduced by hydrogen. Once the temperature was
≥ 700 °C, ludwigite was rapidly reduced and decomposed
into a mixture of metallic iron and suanite with a porous
structure.
(3) The optimal reduction conditions for boron-bear-
ing iron concentrate in a fluidized bed were a reduction
temperature of 800 °C, H2 concentration of 80%, and
reduction time of 40 min, and the metallization degree of
the reduced product reached 82.95%. Therefore, fluidized
hydrogen reduction achieved the effective and clean reduc-
tion of boron-bearing iron concentrate.
REFERENCES
An, J., Xue, X., Life cycle environmental impact assessment
of borax and boric acid production in China. Journal of
Cleaner Production, 2014, 66, 121–127.
Brunauer, S., Emmett, P.H., Teller, E., Adsorption of Gases
in Multimolecular Layers. Journal of the American
Chemical Society, 1938, 60(2), 309–319.
Chu, M., Zhao, J.Q., Fu, X.J., et al., New efficient pro-
cess utilizing ludwigite on gas-based shaft furnace
direct reduction and electric furnace smelting separa-
tion. Journal of Northeastern University Natural Science,
2016, 37, 805–809.
Ding, D., Peng, H., Peng, W., et al., Isothermal hydro-
gen reduction of oxide scale on hot-rolled steel strip
in 30 pct H2N2 atmosphere. International Journal of
Hydrogen Energy, 2017, 42(50), 29921–29928.
Figure 13. Schematic diagram of hydrogen reduction of boron-bearing iron concentrate
of the particles. Ultimately, a tiny amount of wüstite was
unable to be reduced.
CONCLUSIONS
This study proposed a fluidized hydrogen reduction tech-
nology to treat boron-bearing iron concentrate. The effects
of the reduction conditions on the metallization degree
and the mineral phase composition of the reduced prod-
ucts were investigated, and the formation and structural
evolution of metallic iron during the fluidized reduction
process were discussed in detail. The main conclusions were
as follows:
(1) At 500–550 °C, magnetite was reduced directly to
porous metallic iron by hydrogen. Above 600 °C, the reac-
tion path was magnetite → wüstite → metallic iron, and
the wüstite was surrounded by a dense iron layer, which
hindered the direct contact and reaction between hydrogen
and iron oxide, resulting in a significant drop in the metal-
lization degree at 600–650 °C.
(2) The reduction behavior of ludwigite was observed
for the first time. When the reduction temperature was
700 °C, the structure of ludwigite was stable and could
not be reduced by hydrogen. Once the temperature was
≥ 700 °C, ludwigite was rapidly reduced and decomposed
into a mixture of metallic iron and suanite with a porous
structure.
(3) The optimal reduction conditions for boron-bear-
ing iron concentrate in a fluidized bed were a reduction
temperature of 800 °C, H2 concentration of 80%, and
reduction time of 40 min, and the metallization degree of
the reduced product reached 82.95%. Therefore, fluidized
hydrogen reduction achieved the effective and clean reduc-
tion of boron-bearing iron concentrate.
REFERENCES
An, J., Xue, X., Life cycle environmental impact assessment
of borax and boric acid production in China. Journal of
Cleaner Production, 2014, 66, 121–127.
Brunauer, S., Emmett, P.H., Teller, E., Adsorption of Gases
in Multimolecular Layers. Journal of the American
Chemical Society, 1938, 60(2), 309–319.
Chu, M., Zhao, J.Q., Fu, X.J., et al., New efficient pro-
cess utilizing ludwigite on gas-based shaft furnace
direct reduction and electric furnace smelting separa-
tion. Journal of Northeastern University Natural Science,
2016, 37, 805–809.
Ding, D., Peng, H., Peng, W., et al., Isothermal hydro-
gen reduction of oxide scale on hot-rolled steel strip
in 30 pct H2N2 atmosphere. International Journal of
Hydrogen Energy, 2017, 42(50), 29921–29928.
Figure 13. Schematic diagram of hydrogen reduction of boron-bearing iron concentrate