JP3395803B2 - Method for producing iron oxide by roasting method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing iron oxide by a roasting method from a waste hydrochloric acid solution containing iron chloride generated when a steel material is pickled.

[0002]

2. Description of the Related Art An outline of a roasting furnace used for roasting a waste hydrochloric acid solution to produce iron oxide is shown in FIG. The sprayed product 2 of waste hydrochloric acid sprayed from the upper part of the roasting furnace comes into contact with the swirl flow 5 created by the combustion gas of the coke oven gas (hereinafter referred to as COG) in the roasting furnace, and the following formula (1) and Iron oxide 9 is obtained by the reaction represented by the formula (2). [Reaction in roasting furnace] 2FeCl ₂ + 2H ₂ O + 1 / 2O ₂ → Fe ₂ O ₃ + 4HCl …… (1) FeCl ₃ + 3H ₂ O → Fe ₂ O ₃ + 6HCl …………………… (2 ) And the average particle diameter of iron oxide (Shimadzu SS-100
In the conventional method, the m value (air ratio) is kept constant and the atmospheric temperature in the roasting furnace is changed in order to control the measurement by the air permeation method using the above method and the same hereinafter.

Considering the mechanism of iron oxide formation
First, from the surface of the sprayed droplet, H₂O, HCl
Evaporates and precipitates on the droplet surface₂A thin film of
It Next, FeCl₂When the water of crystallization of
Fe produced by the reaction₂O ₃Is generated. afterwards,
By receiving heat, Fe₂O₃Particles of each other join together
It is considered that the lengthening leads to the formation of primary particles. Obey
The greater the thermal energy applied to the particles,
The higher the body temperature, the higher the particle binding rate, so
The average particle size of the primary particles becomes large.

[0004]

However, in the conventional method of changing the body temperature, there is a problem that the COG amount increases and the energy consumption rate increases, especially when the average particle diameter is increased. was there.

For example, the average particle diameter of 0.71 μm is 0.9
When changing to 2 μm, the spray amount is 4.0 m.
³ / h, body temperature 540 ° C., COG amount 550 N (standard state) m ³ / h, roasted under operating conditions, average particle size 0.71
To obtain an average particle size of 0.92μ, the iron oxide that had obtained μm had the same spray amount, the body temperature was 610 ° C., and the CO
A G amount of 620 Nm ³ / h is required, and the required energy intensity increases. Here, the energy intensity is [the required amount of energy (the required energy cost + C
OG gas energy cost) / iron oxide production (g)]. Therefore, an object of the present invention is to provide a technique for increasing the average particle diameter, which solves such problems.

[0006]

In order to solve such a problem, the present invention is to increase the combustion air amount added to the fuel gas without changing the body temperature, that is, the COG amount is hardly changed. The inventors have found that the average particle diameter increases and have reached the present invention. This applies to actual operations. That is, the present invention is a method of producing iron oxide by a roasting method from a waste hydrochloric acid solution containing iron chloride, by simultaneously controlling the roasting furnace body temperature, the fuel gas amount, and the m value during roasting, and Provided is a method for producing iron oxide by a roasting method in which the average particle size of iron oxide is controlled without increasing the unit consumption. Further, in a method for producing iron oxide from a waste hydrochloric acid solution containing iron chloride by a roasting method, increasing the volume ratio of the combustion air amount to the fuel gas amount during roasting without raising the temperature of the body of the roasting furnace. Provides a method for producing iron oxide by a roasting method, which increases the average particle size of iron oxide.

The present invention will be described in detail below. An example of a cross-sectional view of a roasting furnace used for producing iron oxide from waste hydrochloric acid is shown in FIG. 1, and the present invention will be described using this. As shown in FIG. 1, a sprayed product 2 of waste hydrochloric acid is sprayed from a spray nozzle 1. On the other hand, the combustion gas of COG and air injected from the fuel gas inlet 4 produces a swirling flow 5 in the roasting furnace main body 8. Sprayed waste hydrochloric acid 2
Comes into contact with the swirl flow 5 of the combustion gas and produces iron oxide 9 by the iron oxide production reaction. At this time, in order to control the average particle diameter, according to the conventional method, the body temperature shown by the body thermometer 6 is changed. This is shown in Table 2 as Comparative Example 1, and the average particle size increases as the body temperature rises, but at the same time, the fuel gas amount also increases. For example, an average particle size of 0.7 μm to 0.9
About 13% by volume of fuel gas is used to increase to μm
It was common for the energy consumption rate to increase as well.

On the other hand, in the present invention, the temperature of the body of the roasting furnace is
At the same time as the fuel gas amount and m value
The average particle size can be controlled without increasing the unit consumption.
In particular, mix while maintaining the same amount of fuel gas injection.
Manufacturing by increasing the injection amount of combustion air
It is possible to increase the average particle diameter of iron oxide. Book
The waste hydrochloric acid solution used in the invention is F produced by pickling steel sheets.
eCl₂, FeCl ₃Waste liquid of hydrochloric acid containing
It can be anything. In the waste hydrochloric acid solution,
180 to 280 g of iron ions / m³Contained
There is. Spray amount of waste hydrochloric acid solution is 2.5-4.5m³
/ H is preferable. Fuel gas used in the present invention
Can use gas generated from coke ovens, etc.
it can. When injecting fuel gas into the roasting furnace,
Mix and pour into a roasting furnace. Mixing fuel gas and combustion air
The total ratio is 1.3 to 2.1, preferably 1.5 in terms of air ratio.
Set to ~ 1.8. Below 1.3, the combustion temperature is high
The chamber was damaged, and if it exceeds 2.1, the combustion temperature is low,
Not baked. The roasting furnace body temperature is preferably 530
-560 degreeC, More preferably, it is 530-540 degreeC.
It is necessary to keep the temperature of the body of the roasting furnace higher than this range.
If it goes down, the energy consumption rate goes up and it is not economical
Is. And without raising the temperature of the body of the roasting furnace more than before,
If the m value is increased without increasing the fuel gas amount,
Without increasing the energy intensity, the average particle size is 0.70 to 0.
Large iron oxide of 95 μm, especially 0.90 to 0.92 μm
Particles are obtained. The injection amount of fuel gas and combustion air is
Depending on the scale of the furnace, for example, a diameter of 6.5m,
In a cylindrical roasting furnace with a height of 16 m, the fuel gas amount is 500
~ 700 Nm³/ H, the amount of combustion air is 3225 to 54
20 Nm³/ H is preferable. The iron oxide of the present invention
As the roasting furnace used for manufacturing, the acid produced by the normal roasting method is used.
Any material can be used as long as it is used for the production of iron oxide, for example, the diameter
A roasting furnace having a cylindrical diameter of 6.5 m and a height of 16 m can be mentioned.

In the method for producing iron oxide using the roasting furnace of the present invention, a roasting furnace, for example, a roasting furnace as shown in FIG. 1 is used, and the fuel gas inlet on the side surface of the roasting furnace body 8 is used. Injecting fuel gas and combustion air from 4 at an appropriate air ratio to raise the temperature of the body of the roasting furnace, while spraying the waste hydrochloric acid solution from the spray nozzle 1 at the top of the body 8 of the roasting furnace, The sprayed particles of the waste hydrochloric acid solution are brought into contact with the swirling flow of the combustion gas and reacted to produce iron oxide 9. HCl and combustion gas generated by this reaction are
It is discharged from the Cl outlet 7. Then, by controlling the fuel gas amount and the combustion air amount, iron oxide having a desired average particle diameter can be obtained without increasing the energy consumption rate.

(Operation) Next, the cause of growth of the particle size will be described. FeCl ₂ in the waste hydrochloric acid solution requires thermal energy when it reacts with moisture and oxygen in the atmosphere or fuel gas to produce Fe ₂ O ₃ particles. When the body temperature is raised, that is, when the amount of energy given per unit time is increased, this reaction occurs quickly in a short time. That is, the reaction speed is fast. After the spraying, if the reaction continues to occur until it falls to the bottom of the roasting furnace, if the dropping time is constant, the particle size grows as the reaction speed increases, and the average particle size increases. Become. This is the principle of increasing the average particle size when the body temperature is increased.

On the other hand, according to the present invention, the reaction rate does not change because the body temperature is not raised, but the swirling flow rate in the roasting furnace is increased by increasing the amount of combustion air to give lift to the particles after spraying. The particles to fall to the bottom of the roasting furnace. Since a reaction occurs while falling, the growth of particles progresses and the average particle size increases. This is the principle of increasing the average particle size by increasing the combustion air amount of the present invention,
The inventor has found out this principle and arrived at the present invention.

This iron oxide is useful as iron oxide for ferrite, iron oxide for pigments and the like.

[0013]

EXAMPLES The present invention will be specifically described below based on examples of the present invention, but the present invention is not limited thereto. (Example 1) Diameter 6.5m and height 16m shown in FIG.
The waste hydrochloric acid solution was sprayed at 4 m ³ / h from the upper part of the cylindrical roasting furnace, and COG and air were injected from the fuel gas inlet below the main body of the roasting furnace as shown in Table 1 below, and roasting was performed. did. Then, when the roasting temperatures reached the temperatures shown in Table 1, the roasting was continued while changing the fuel gas amount and the combustion air amount while observing the fuel gas amount. At this time, the body temperature, m value, and average particle size were measured, and the results are shown in Table 1.

[0014]

[Table 1]

When the amount of air was increased without increasing the temperature of the body, that is, the m value was increased, the average particle size was 0.7 μm.
m to 0.9 μm. At this time, since it is not necessary to increase the temperature of the body, the amount of fuel gas has not increased, and the average particle size can be controlled without increasing the energy intensity.

(Comparative Example 1) Using the same roasting furnace as in Example 1, the waste hydrochloric acid solution was sprayed at 4 m ³ / h from the upper part of the roasting furnace, and COG and air were supplied from the fuel gas inlet located below. It was injected and roasted as shown in Table 2 below. Then, from the time when the roasting temperature reached the temperature shown in Table 2, the amount of fuel gas and the amount of air were set to the supply amounts shown in Table 2, and roasting was continued.
At this time, the body temperature, m value, and average particle size were measured, and the results are shown in Table 2.

[0017]

[Table 2]

According to the conventional method shown in Table 2, the average particle size increases as the body temperature rises, but at the same time, the fuel gas amount also increases. That is, in order to increase the average particle diameter from 0.7 μm to 0.9 μm, the fuel gas amount increased by about 13% by volume, and the energy consumption rate increased.

[0019]

INDUSTRIAL APPLICABILITY The present invention makes it possible to control the average particle diameter of iron oxide by changing the ratio of the fuel gas and the amount of air injected into the roasting furnace when producing the iron oxide in the roasting furnace. did.
This makes it possible to perform control without increasing the energy intensity even when increasing the average particle diameter, because it does not depend on increasing the fuel gas amount and changing the body temperature as in the conventional technique. It was

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a roasting apparatus for showing an outline when iron oxide is produced from waste hydrochloric acid by a roasting method.

[Explanation of symbols]

1. spray nozzle 2. Waste hydrochloric acid spray liquid 3. Rotary bubble 4. Fuel gas inlet (COG + air) 5. Swirling flow due to combustion gas 6. Body thermometer 7. Combustion gas and HCl outlet 8. Roasting furnace body 9. iron oxide

Continuation of front page (56) Reference JP-A-7-41320 (JP, A) JP-A-7-71881 (JP, A) JP-A-6-56431 (JP, A) JP-A-7-89727 (JP , A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C01G 49/00-49/08 C04B 35/26-35/40 H01F 1/12-1/375

Claims (2)

(57) [Claims] 1. A method for producing iron oxide from a waste hydrochloric acid solution containing iron chloride by a roasting method, in which the temperature of the roasting furnace body, the amount of fuel gas and the m value (air ratio) are simultaneously controlled during roasting. And controlling the average particle size of iron oxide without increasing the energy consumption rate. 2. A method for producing iron oxide from a waste hydrochloric acid solution containing iron chloride by a roasting method, wherein the volume ratio of the amount of combustion air to the amount of fuel gas during roasting is increased without raising the temperature of the body of the roasting furnace. A method for producing iron oxide by a roasting method, characterized in that the average particle size of iron oxide is increased by increasing the temperature.