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X. Wu
Process Principle
The smelting process mechanism is that oxygen-enriched air is fed into the furnace
from a tuyere located about 0.50 m below the plane of the standing melt on the side
wall of the smelting furnace, to make the upper melt in the molten bath bubble strongly
and stirred violently. Solid furnace charge is added into a molten bath of molten slag
stirred at a temperature of 1000–1400 °C, particles or polymers of the furnace charge
are wetted by the slag and heated based on the temperature difference between the slag
and the furnace charge particles. The fusible components are preferentially melted to
form metal droplets in the slag. High melting point components such as flux and coal
are strongly stirred or melted into slag, or burned, or reacted with oxygen in slag. The
gas blown into the slag melt acts on the slag at the phase interface and changes the
composition of the liquid phase and the gaseous phase accordingly until a chemical
equilibrium is established between the two phases. Because of the large area of the
phase interface and the high stirring energy given by the gas to the molten bath, the
heat and mass transfer process in the furnace are accelerated, the composition of each
phase tends to be balanced, and the phase separation process is greatly accelerated.
The characteristic of oxygen-enriched air side-blown bath smelting is that the
molten bath in the furnace is divided into two layers by air blown in at a certain
height. The upper layer is stirred by gas to obtain turbulent motion. The furnace
charge is added to the melt layer, and heat and mass transfer processes between
the melt and the added furnace charge and between the melt and the blown gas are
realized therein. When the uniform distribution of the required stirring energy is
formed in the upper stirring layer, the reaction speed in the entire melt will increase
many times. This is because stirring the melt will make the added solid, liquid, and
gas dispersed rapidly and evenly throughout the upper melt, thus greatly increasing
the area of the phase interface.
In the smelting process, the ideal conditions for oxidation, reduction, and any other
pyrometallurgical changes are actually created in the stirring layer on the upper part
of the melt. The research shows that the material composition of the upper stirring
layer is basically consistent with the final equilibrium phase composition of the real
system. When the furnace charge to be treated and the gas required by the process
is added to the melt, the composition of the molten bath has not changed much due
to the extremely high reaction speed, although its composition differs greatly from
the material composition of the molten bath in the furnace. Therefore, in continuous
operation, what actually exists in the furnace is the final product of the production
process.
In addition, below the level at which the melt is blown; there is a lower melt that
is less stirring than the upper melt. In this calm area at the lower part, the different
liquid droplets forced to grow in the upper layer will rapidly separate according to
the difference in specific gravity.
X. Wu
Process Principle
The smelting process mechanism is that oxygen-enriched air is fed into the furnace
from a tuyere located about 0.50 m below the plane of the standing melt on the side
wall of the smelting furnace, to make the upper melt in the molten bath bubble strongly
and stirred violently. Solid furnace charge is added into a molten bath of molten slag
stirred at a temperature of 1000–1400 °C, particles or polymers of the furnace charge
are wetted by the slag and heated based on the temperature difference between the slag
and the furnace charge particles. The fusible components are preferentially melted to
form metal droplets in the slag. High melting point components such as flux and coal
are strongly stirred or melted into slag, or burned, or reacted with oxygen in slag. The
gas blown into the slag melt acts on the slag at the phase interface and changes the
composition of the liquid phase and the gaseous phase accordingly until a chemical
equilibrium is established between the two phases. Because of the large area of the
phase interface and the high stirring energy given by the gas to the molten bath, the
heat and mass transfer process in the furnace are accelerated, the composition of each
phase tends to be balanced, and the phase separation process is greatly accelerated.
The characteristic of oxygen-enriched air side-blown bath smelting is that the
molten bath in the furnace is divided into two layers by air blown in at a certain
height. The upper layer is stirred by gas to obtain turbulent motion. The furnace
charge is added to the melt layer, and heat and mass transfer processes between
the melt and the added furnace charge and between the melt and the blown gas are
realized therein. When the uniform distribution of the required stirring energy is
formed in the upper stirring layer, the reaction speed in the entire melt will increase
many times. This is because stirring the melt will make the added solid, liquid, and
gas dispersed rapidly and evenly throughout the upper melt, thus greatly increasing
the area of the phase interface.
In the smelting process, the ideal conditions for oxidation, reduction, and any other
pyrometallurgical changes are actually created in the stirring layer on the upper part
of the melt. The research shows that the material composition of the upper stirring
layer is basically consistent with the final equilibrium phase composition of the real
system. When the furnace charge to be treated and the gas required by the process
is added to the melt, the composition of the molten bath has not changed much due
to the extremely high reaction speed, although its composition differs greatly from
the material composition of the molten bath in the furnace. Therefore, in continuous
operation, what actually exists in the furnace is the final product of the production
process.
In addition, below the level at which the melt is blown; there is a lower melt that
is less stirring than the upper melt. In this calm area at the lower part, the different
liquid droplets forced to grow in the upper layer will rapidly separate according to
the difference in specific gravity.