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L. Xu and S. Ma
Process Flow
Zinc residues are fumed in SSC + FF. As mentioned above, the main energy consumption is the heat absorption of residues melting, and the removal of sulfur is
also in the melting stage. The SSC directly injects natural gas or pulverized coal
from the side lance into the molten bath for heating and adds some crushed coal into
the zinc residues from the top of the furnace. The crushed coal combusts with the
oxygen of the lance and participates in the reduction reaction. Oxygen-enriched air
concentration in the furnace injected by side lance is more than 50%, and excess
oxygen coefficient is controlled from 0.8 to 0.9. The spray gun has multi-channel
structure, fast burning speed, and flame temperature over 2000 °C. The combustion
flame contacts the melt directly, and the gas injected into the molten bath at high
speed ensures the stirring strength of the molten bath, accelerates the heat and mass
transfer process in the molten bath, and completes the rapid melting of zinc residues.
At the same time, the use of high oxygen-enriched air to combustion reduces the
volume of offgas, improves the thermal efficiency of SSC, and significantly reduces
the fuel rate. The temperature of the molten bath is controlled from 1200 to 1250 °C.
A small part of zinc and most of lead, silver, and germanium volatilize into the offgas.
The molten high zinc slag is discharged into the FF regularly through the chute.
The air and pulverized coal injected by the FF from the side tuyere. The incomplete
combustion of pulverized coal produces CO and reductive atmosphere at the same
time of heating. The excess oxygen coefficient of molten bath is controlled from 0.6 to
0.7. The FF uses air combustion. The blast intensity is greater than 20 Nm
3 /(min m
2 ),
which provides enough stirring strength for the molten bath. The temperature of
molten bath is maintained at 1250–1300 °C, and most of lead and zinc are reduced
and volatilized into offgas. The final slag of FF is piled up after water crushing. The
final slag contains less than 2% zinc and less than 0.2% lead.
The process flow chart is as in Fig. 1.
Engineering Cases
Overview
Yunnan Chihong Zn & Ge Huize smelter is currently producing 150,000 tons of
zinc and 80,000 tons of lead per year. Among them, the original design of lead
smelting process is TSL oxidation + SSC reduction, SSC reduction slag into the
FF; zinc smelting process is roasting + low acid leaching, leaching residues, and
SSC reduction slag of lead into the FF together. Due to the increase of production
capacity of zinc system and the increase of zinc residues, the treatment capacity of FF
is insufficient. In addition, there are a lot of low-grade lead-zinc oxide ore deposits in
the mine of the Yunnan Chihong Zn & Ge. With the normal mining and production
of the mine, a lot of lead-zinc oxide ores are still being produced every year and
L. Xu and S. Ma
Process Flow
Zinc residues are fumed in SSC + FF. As mentioned above, the main energy consumption is the heat absorption of residues melting, and the removal of sulfur is
also in the melting stage. The SSC directly injects natural gas or pulverized coal
from the side lance into the molten bath for heating and adds some crushed coal into
the zinc residues from the top of the furnace. The crushed coal combusts with the
oxygen of the lance and participates in the reduction reaction. Oxygen-enriched air
concentration in the furnace injected by side lance is more than 50%, and excess
oxygen coefficient is controlled from 0.8 to 0.9. The spray gun has multi-channel
structure, fast burning speed, and flame temperature over 2000 °C. The combustion
flame contacts the melt directly, and the gas injected into the molten bath at high
speed ensures the stirring strength of the molten bath, accelerates the heat and mass
transfer process in the molten bath, and completes the rapid melting of zinc residues.
At the same time, the use of high oxygen-enriched air to combustion reduces the
volume of offgas, improves the thermal efficiency of SSC, and significantly reduces
the fuel rate. The temperature of the molten bath is controlled from 1200 to 1250 °C.
A small part of zinc and most of lead, silver, and germanium volatilize into the offgas.
The molten high zinc slag is discharged into the FF regularly through the chute.
The air and pulverized coal injected by the FF from the side tuyere. The incomplete
combustion of pulverized coal produces CO and reductive atmosphere at the same
time of heating. The excess oxygen coefficient of molten bath is controlled from 0.6 to
0.7. The FF uses air combustion. The blast intensity is greater than 20 Nm
3 /(min m
2 ),
which provides enough stirring strength for the molten bath. The temperature of
molten bath is maintained at 1250–1300 °C, and most of lead and zinc are reduced
and volatilized into offgas. The final slag of FF is piled up after water crushing. The
final slag contains less than 2% zinc and less than 0.2% lead.
The process flow chart is as in Fig. 1.
Engineering Cases
Overview
Yunnan Chihong Zn & Ge Huize smelter is currently producing 150,000 tons of
zinc and 80,000 tons of lead per year. Among them, the original design of lead
smelting process is TSL oxidation + SSC reduction, SSC reduction slag into the
FF; zinc smelting process is roasting + low acid leaching, leaching residues, and
SSC reduction slag of lead into the FF together. Due to the increase of production
capacity of zinc system and the increase of zinc residues, the treatment capacity of FF
is insufficient. In addition, there are a lot of low-grade lead-zinc oxide ore deposits in
the mine of the Yunnan Chihong Zn & Ge. With the normal mining and production
of the mine, a lot of lead-zinc oxide ores are still being produced every year and