Zinc Residue Fuming Process in Side-Submerged Combustion …
267
ZnS + 3/2O 2(g) = ZnO + SO 2(g) − 444 kJ/mol
(5)
ZnSO 4 = ZnO + SO 2(g) + 1/2O 2(g) + 333 kJ/mol
(6)
ZnO · SiO 2 + CaO = ZnO + CaO · SiO 2 − 88 kJ/mol
(7)
PbSO 4 = PbO + SO 2(g) + 1/2O 2(g) + 405 kJ/mol
(8)
PbO + CO (g) = Pb (g) + CO 2(g) + 131 kJ/mol
(9)
Fe 2 O 3 + CO (g) = 2FeO + CO 2(g) + 5 kJ/mol
(10)
FeO + SiO 2 − 2FeO · SiO 2 − 33 kJ/mol
(11)
SiO 2 + CaO = CaO · SiO 2 − 89 kJ/mol
(12)
H 2 O (1) = H 2 O (g) + 44 kJ/mol
(13)
Reaction (1) is coal combustion reaction. The heat generated by combustion
ensures the temperature of molten pool. The CO produced by reaction (2) maintains a reductive atmosphere in the molten bath area and ensures the reduction and
volatilization of metals such as Zn and Pb.
Reactions (3), (4), (8), (9), (10), and (13) are the main reactions in zinc residues
smelting, which need to absorb a lot of reaction heat. Reactions (5), (7), (11), and
(12) are exothermic reactions, but these substances have less content or exothermic
in the leaching residue, which has little influence on the overall thermal balance. In
addition, the melting of all kinds of substances needs to absorb a lot of heat.
Therefore, it can be seen from the above reactions that in order to ensure the reduction and volatilization of lead and zinc, the reducing atmosphere and bath temperature
must be ensured. The process of zinc residues smelting mainly consists of two steps:
melting and reducing volatilization, while the main heat consumption in the whole
process is melting. Therefore, the whole smelting process of zinc leaching residues
is divided into two stages: SSC melting and fuming furnace fuming. SSC uses high
oxygen-enriched combustion. Fuel combustion provides heat while maintaining a
weak reductive atmosphere in the furnace, so as to save energy consumption. In the
fuming stage, only hot slag is treated, and the heat consumption is mainly lead and
zinc reduction,volatilization heat absorption, and furnace heat loss. Therefore, the
energy consumption in the fuming stage is low.
267
ZnS + 3/2O 2(g) = ZnO + SO 2(g) − 444 kJ/mol
(5)
ZnSO 4 = ZnO + SO 2(g) + 1/2O 2(g) + 333 kJ/mol
(6)
ZnO · SiO 2 + CaO = ZnO + CaO · SiO 2 − 88 kJ/mol
(7)
PbSO 4 = PbO + SO 2(g) + 1/2O 2(g) + 405 kJ/mol
(8)
PbO + CO (g) = Pb (g) + CO 2(g) + 131 kJ/mol
(9)
Fe 2 O 3 + CO (g) = 2FeO + CO 2(g) + 5 kJ/mol
(10)
FeO + SiO 2 − 2FeO · SiO 2 − 33 kJ/mol
(11)
SiO 2 + CaO = CaO · SiO 2 − 89 kJ/mol
(12)
H 2 O (1) = H 2 O (g) + 44 kJ/mol
(13)
Reaction (1) is coal combustion reaction. The heat generated by combustion
ensures the temperature of molten pool. The CO produced by reaction (2) maintains a reductive atmosphere in the molten bath area and ensures the reduction and
volatilization of metals such as Zn and Pb.
Reactions (3), (4), (8), (9), (10), and (13) are the main reactions in zinc residues
smelting, which need to absorb a lot of reaction heat. Reactions (5), (7), (11), and
(12) are exothermic reactions, but these substances have less content or exothermic
in the leaching residue, which has little influence on the overall thermal balance. In
addition, the melting of all kinds of substances needs to absorb a lot of heat.
Therefore, it can be seen from the above reactions that in order to ensure the reduction and volatilization of lead and zinc, the reducing atmosphere and bath temperature
must be ensured. The process of zinc residues smelting mainly consists of two steps:
melting and reducing volatilization, while the main heat consumption in the whole
process is melting. Therefore, the whole smelting process of zinc leaching residues
is divided into two stages: SSC melting and fuming furnace fuming. SSC uses high
oxygen-enriched combustion. Fuel combustion provides heat while maintaining a
weak reductive atmosphere in the furnace, so as to save energy consumption. In the
fuming stage, only hot slag is treated, and the heat consumption is mainly lead and
zinc reduction,volatilization heat absorption, and furnace heat loss. Therefore, the
energy consumption in the fuming stage is low.