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B.-W. Liu et al.
from wet-process phosphoric acid; in the production of wet-process phosphoric acid
production. At present, the main source of phosphogypsum is wet-process phosphoric
acid. The main chemical reaction is as follows [4]:
Ca 5 F(PO 4 ) 3 + 5H 2 SO 4 + 10H 2 O = 3H 3 PO 4 + 5CaSO 4 · 2H 2 O + HF (1)
On average, each ton of wet-process phosphoric acid is produced, and about 4.5–
5.0 tons of phosphogypsum is discharged. At present, the total annual output of world
wet-process phosphoric acid is about 260 million tons, and the total annual output of
by-product phosphogypsum is about 150 million tons. With the rapid development
of China’s phosphogypsum industry, the cumulative stock of phosphogypsum byproducts ranks first in the world. Data shows that China’s annual emissions of phosphogypsum have reached 75 million tons. After years of accumulation, China’s phosphogypsum stacks The stock has exceeded 600 million tons. However, the utilization
rate is still less than 40% [5].
The treatment of phosphogypsum is generally natural accumulation [6]. The accumulation of a large amount of phosphogypsum not only takes up a lot of land
resources, but also seriously damages the environment. With the development of
the phosphorus compound fertilizer production industry, the emissions of phosphogypsum continue to increase. How to solve the comprehensive utilization of
phosphogypsum has become an urgent problem. At present, the conversion of phosphogypsum into ammonium sulfate is divided into double decomposition method
and carbonization method. Cordell [7] first discovered the use of phosphogypsum
and (NH 4 ) 2 CO 3 to produce (NH 2 )SO 4 fertilizer and CaCO 3 as raw materials for
building materials, which is a very promising comprehensive utilization approach
for phosphogypsum. Yang [8] and others used NH 4 HCO 3 as a carbon source to react
with phosphogypsum to produce (NH 2 )SO 4 and CaCO 3 , which is also a way of
comprehensive utilization of phosphogypsum. Because the use of (NH 4 ) 2 CO 3 and
NH 4 HCO 3 to produce (NH 2 )SO 4 is not economical, the metathesis method cannot
be used for large-scale industrial production. In order to save costs, He [9] and others
explored the use of CO 2 as a carbon source to react with phosphogypsum under alkaline conditions, which has certain guiding significance for the industrial production
of phosphogypsum (NH 2 )SO 4 and CaCO 3 .
The micro-bubble is widely used in chemical, metallurgical, biopharmaceutical,
and other fields [10–12]. During the stirring process, the bubbles continue to rupture
and fusion, resulting in size distribution of bubbles in the reactor. For a long time,
scholars in various fields have devoted themselves to studying the size and distribution
of bubbles in gas–liquid two-phase stirred reactors. The mass transfer and reaction
processes of the gas–liquid two-phase in the reactor are carried out on the surface of
the bubble, so the size of the bubble is a very important factor in the chemical reaction
with the participation of gas [13]. The mass transfer between gas and liquid phases
has a direct impact on the reaction time and the size of the reactor [14]. The better
the effect of micro-bubble, the more conducive to the full progress of the reaction.
This experiment uses the method of physical simulation to study the effect of the
micro-bubble. By improving the effect of miniaturization of bubbles, it promotes
B.-W. Liu et al.
from wet-process phosphoric acid; in the production of wet-process phosphoric acid
production. At present, the main source of phosphogypsum is wet-process phosphoric
acid. The main chemical reaction is as follows [4]:
Ca 5 F(PO 4 ) 3 + 5H 2 SO 4 + 10H 2 O = 3H 3 PO 4 + 5CaSO 4 · 2H 2 O + HF (1)
On average, each ton of wet-process phosphoric acid is produced, and about 4.5–
5.0 tons of phosphogypsum is discharged. At present, the total annual output of world
wet-process phosphoric acid is about 260 million tons, and the total annual output of
by-product phosphogypsum is about 150 million tons. With the rapid development
of China’s phosphogypsum industry, the cumulative stock of phosphogypsum byproducts ranks first in the world. Data shows that China’s annual emissions of phosphogypsum have reached 75 million tons. After years of accumulation, China’s phosphogypsum stacks The stock has exceeded 600 million tons. However, the utilization
rate is still less than 40% [5].
The treatment of phosphogypsum is generally natural accumulation [6]. The accumulation of a large amount of phosphogypsum not only takes up a lot of land
resources, but also seriously damages the environment. With the development of
the phosphorus compound fertilizer production industry, the emissions of phosphogypsum continue to increase. How to solve the comprehensive utilization of
phosphogypsum has become an urgent problem. At present, the conversion of phosphogypsum into ammonium sulfate is divided into double decomposition method
and carbonization method. Cordell [7] first discovered the use of phosphogypsum
and (NH 4 ) 2 CO 3 to produce (NH 2 )SO 4 fertilizer and CaCO 3 as raw materials for
building materials, which is a very promising comprehensive utilization approach
for phosphogypsum. Yang [8] and others used NH 4 HCO 3 as a carbon source to react
with phosphogypsum to produce (NH 2 )SO 4 and CaCO 3 , which is also a way of
comprehensive utilization of phosphogypsum. Because the use of (NH 4 ) 2 CO 3 and
NH 4 HCO 3 to produce (NH 2 )SO 4 is not economical, the metathesis method cannot
be used for large-scale industrial production. In order to save costs, He [9] and others
explored the use of CO 2 as a carbon source to react with phosphogypsum under alkaline conditions, which has certain guiding significance for the industrial production
of phosphogypsum (NH 2 )SO 4 and CaCO 3 .
The micro-bubble is widely used in chemical, metallurgical, biopharmaceutical,
and other fields [10–12]. During the stirring process, the bubbles continue to rupture
and fusion, resulting in size distribution of bubbles in the reactor. For a long time,
scholars in various fields have devoted themselves to studying the size and distribution
of bubbles in gas–liquid two-phase stirred reactors. The mass transfer and reaction
processes of the gas–liquid two-phase in the reactor are carried out on the surface of
the bubble, so the size of the bubble is a very important factor in the chemical reaction
with the participation of gas [13]. The mass transfer between gas and liquid phases
has a direct impact on the reaction time and the size of the reactor [14]. The better
the effect of micro-bubble, the more conducive to the full progress of the reaction.
This experiment uses the method of physical simulation to study the effect of the
micro-bubble. By improving the effect of miniaturization of bubbles, it promotes