JP2002285254A - Method for manufacturing zinc oxide calcine or zinc oxide briquette - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an amount of heat for manufacturing a zinc oxide calcine or a zinc oxide briquette without increasing the moisture content of the resultant zinc oxide cake. SOLUTION: This method comprises the following steps: (1) a step of charging zinc-containing dust from steelworks into a reducing roasting furnace together with a reducing agent to perform reduction; (2) a step of applying wet treatment to the crude zinc oxide recovered from the reducing roasting furnace; (3) a step of applying dehydration treatment to the resultant zinc oxide slurry; and (4) a step of charging the resultant zinc oxide cake into a drying-heating furnace to carry out firing. By the above wet treatment, impurities such as halides can be removed. The method for dehydrating the zinc oxide slurry in the above wet treatment process comprises the following steps: (A) a first-stage dehydration step 2; (B) a step of adding adjusting water to the zinc oxide cake resultant from the first-stage dehydration step 2 in an equalizing tank 3 while regulating additive quantity by the use of a water-volume-regulating device 3b so that slurry concentration measured by a slurry-concentration-measuring instrument 3a is made constant; and (C) a second-stage dehydration step 4.

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 zinc oxide ore or zinc oxide ore, and more particularly, to a method for reducing iron dust generated in a blast furnace, an electric furnace or the like in the steel industry in a reduction roasting furnace. The method for producing zinc oxide ore or zinc oxide ore by collecting zinc oxide and removing impurities such as halides by performing a wet treatment and then charging the same in a dry heating furnace. It relates to the dehydration method in the inside.

[0002]

2. Description of the Related Art Steel dust generated from blast furnaces and electric furnaces in the iron and steel industry contains a considerable amount of zinc component and lead component in addition to iron oxide which is a main component thereof. It has been practiced to recover components and lead components as zinc oxide ore or zinc oxide ore.

In the method for producing zinc oxide ore or zinc oxide ore, halides are removed by subjecting crude zinc oxide obtained from a reduction roasting furnace to a wet treatment, and the crude zinc oxide is calcined in a dry heating furnace. There is a method of performing granulation.

[0004] The crude zinc oxide recovered from the reduction roasting furnace is
About 8 to 18% by mass of chlorine and about 0 to 5% by mass of halogens such as fluorine are contained as halides such as chlorine compounds or fluorine compounds. Therefore, these halides and other impurities are removed by performing a wet treatment using sodium carbonate, sodium hydroxide, or other chemicals.

[0005] From a zinc oxide slurry from which impurities such as halides have been removed, firing and granulation are performed in a dry heating furnace to produce zinc oxide ore or zinc oxide ore.
At this time, in order to reduce the amount of heat for evaporating water in the drying and heating furnace, the zinc oxide slurry is previously subjected to a dehydration treatment, and the obtained zinc oxide cake is charged into the drying and heating furnace.

[0006] Conventionally, in this dehydration treatment, "one-stage dehydration" has been carried out, which comprises solid-liquid separation using a thickener or a carousel and the like and subjecting the mixture to a dehydrator.

Furthermore, the concentration of the slurry is adjusted by increasing the sedimentation speed of the solid-liquid separation, so that the water content of the zinc oxide cake obtained through the dehydrator is reduced.

[0008]

However, when the composition in the zinc oxide slurry fluctuates, the sedimentation speed fluctuates somewhat. In some cases, it is difficult to obtain a sufficient sedimentation time for solid-liquid separation. In this case, the concentration of the zinc oxide slurry decreases, and the water content of the zinc oxide cake obtained through the dehydrator decreases. There is a problem of rising.

Further, if it takes a long time for sedimentation of solid-liquid separation to adjust the slurry concentration, it becomes difficult to obtain a constant amount of zinc oxide, and the production of zinc oxide ore or zinc oxide ore is reduced. There is a problem of lowering.

[0010] In order to solve the above problems, the method of the present invention provides a method for producing a zinc oxide ore or a zinc oxide ore without increasing the water content of the resulting zinc oxide cake. It is an object of the present invention to provide a method for producing zinc oxide ore or zinc oxide ore characterized by a method for dehydrating a zinc oxide slurry that can be reduced.

[0011]

According to the method for producing zinc oxide ore or zinc oxide ore of the present invention, (1) a steel dust containing zinc is charged together with a reducing agent into a reduction roasting furnace for reduction. (2) performing a wet treatment on the crude zinc oxide recovered from the reduction roasting furnace, (3) performing a dehydration treatment on the obtained zinc oxide slurry, and (4) obtaining the zinc oxide cake. And baking it in a drying and heating furnace.

By the above wet treatment, impurities such as halides are removed.

The method of dewatering the zinc oxide slurry in the wet processing step is as follows: (A) the zinc oxide cake obtained in the first-stage dehydration step and (B) the zinc oxide cake obtained in the first-stage dehydration step have a constant slurry concentration. And (C) a second-stage dehydration step.

By making the slurry concentration constant, 2
The moisture content of the zinc oxide cake coming out of the second-stage dewatering step is reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for dewatering a zinc oxide slurry according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a step of dewatering a zinc oxide slurry.

The zinc oxide slurry is introduced into the solid-liquid separation equipment 1 and concentrated. The concentrated zinc oxide slurry is removed by a dehydrator 2
And the first stage of dehydration is performed.

The zinc oxide cake obtained by the first-stage dehydration is introduced into the adjusting tank 3 and adjusted water is added. Conditioning water is
While measuring the slurry concentration of the zinc oxide slurry to which the conditioning water has been added by the slurry concentration measuring device 3a, the zinc oxide slurry is added by a method of adjusting the addition amount by the water amount adjusting device 3b. That is, if the slurry concentration is equal to or lower than the target slurry concentration, the adjustment water to be added is reduced. As the control method,
It may be based on a known theory.

Further, the zinc oxide slurry obtained by adding the conditioning water is introduced into the dehydrator 4 to perform the second-stage dehydration.

As described above, a zinc oxide cake having a stable and low water content is obtained.

Hereinafter, the present invention will be described in detail.

Table 1 shows an example of the composition of a zinc oxide slurry obtained by wet treatment in the production process of zinc oxide ore or zinc oxide ore.

[0023]

[Table 1]

As shown in Table 1, the zinc oxide slurry from which impurities such as halides were removed was subjected to solid-liquid separation equipment 1
Adjust the slurry concentration with. At this time, a coagulant may be added as a concentration aid for the zinc oxide slurry. As the flocculant, a polymer-based flocculant is usually used,
The addition amount is adjusted within the range of about 10 to 10 ppm by mass. Further, as a coagulation aid, an inorganic coagulant may be added in an amount adjusted to about 0.1 to 10 ppm by mass.

As the solid-liquid separation equipment 1, a thickener, a crowcon or the like can be used. The slurry concentration of the zinc oxide slurry before the solid-liquid separation is about 50 to 200 g / L. By performing the solid-liquid separation, the slurry is concentrated to a slurry concentration of about 400 to 800 g / L.

The concentrated zinc oxide slurry is supplied to a dehydrator 2
To perform the first stage dehydration. As the dehydrator 2, a vacuum suction type dehydrator, a belt type dehydrator, or the like can be used. The moisture content of the zinc oxide cake obtained by the dehydrator 2 may be 50% by mass or less.

The zinc oxide cake obtained in the dehydrator 2 is added to the adjustment water in the adjustment tank 3 to form a slurry.

As the adjusting tank 3, it is desirable to use a tank provided with a stirrer such that the slurry concentration in the adjusting tank 3 becomes uniform. As the conditioned water, fresh water, process water, a solution in which sodium carbonate, sodium hydroxide, or other chemicals are dissolved, a dehydrated filtrate obtained in the dehydrator 2, or the like can be used.

The zinc oxide slurry obtained from the adjusting tank 3 is measured for the slurry concentration by a slurry concentration measuring device 3a installed on the way to the next step. As the slurry concentration measuring device 3a, for example, a slurry concentration meter combining a differential pressure transmitter (Yokogawa Electric's differential pressure transmitter) and a bubbler tube can be used. Alternatively, the measured value measured by the density measuring device may be converted to a slurry concentration instead of the density measuring device. Examples of the density measuring device include a γ-ray density meter (manufactured by Earthnics,
Slurry densitometer) can be used.

Based on the slurry concentration measured by the slurry concentration measuring device 3a, the amount of adjustment water to be added to the adjusting tank 3 is adjusted by the water amount adjusting device 3b so that the slurry concentration can be arbitrarily set. As the water amount adjusting device 3b, for example, a control valve (manufactured by NDV, control valve) can be used.

The zinc oxide slurry whose slurry concentration has been adjusted is subjected to the second-stage dehydration by the dehydrator 4. As the dehydrator 4, a vacuum suction type dehydrator, a belt type dehydrator, or the like can be used.

The lower the moisture content of the zinc oxide cake obtained in the dehydrator 4, the lower the calorific value for producing zinc oxide ore or zinc oxide ore in the drying and heating furnace.

Further, by adjusting the addition amount of the adjusting water as described above so that the slurry concentration of the zinc oxide slurry to be treated in the dehydrator 4 becomes a predetermined value,
And the moisture content of the zinc oxide cake obtained in step (1) can be stably obtained at a constant value, and calcined zinc oxide or zinc oxide ore can be obtained at a constant production rate in a dry heating furnace.

Further, it is possible to stabilize the operation state in the drying and heating furnace.

(Embodiment) [Embodiment 1] An embodiment of the present invention will be described with reference to FIG.

In a rotary furnace for reduction roasting, crude zinc oxide was recovered from steel dust, and impurities such as chlorine were removed using sodium carbonate as the crude zinc oxide to obtain a zinc oxide slurry. 5 to 10 mass pp in the obtained zinc oxide slurry
About m of a polymer-based flocculant was added (the above is not shown), and solid-liquid separation was performed with a thickener 1. The slurry concentration of the zinc oxide slurry obtained by solid-liquid separation with the thickener 1 was unstable between 443 and 640 g / L.

The zinc oxide slurry was subjected to a first-stage dehydration using a vacuum suction type dehydrator 2 (a dehydrator manufactured by Sumitomo Heavy Industries, Ltd.) to obtain a zinc oxide cake. The water content of the obtained zinc oxide cake varied between 31.6 and 43.7% by mass. FIG. 2 is a graph showing the relationship between the slurry concentration of the zinc oxide slurry before the first-stage dehydration treatment and the water content of the zinc oxide cake after the dehydration in this example.

The zinc oxide cake is sent into an adjusting tank 3 equipped with a stirrer, fresh water is added to the adjusting tank 3, and the slurry concentration of the obtained zinc oxide slurry is measured with a density meter 3a (manufactured by Earthnics Co., Ltd.). Densitometer). Further, the amount of fresh water to be added into the adjusting tank 3 was continuously adjusted by a water amount adjusting device 3b (manufactured by NDV, control valve) so that the slurry concentration became 550 to 650 g / L.

The zinc oxide slurry whose slurry concentration was adjusted to 566 to 672 g / L was subjected to second-stage dehydration using a vacuum suction type dehydrator 2 to obtain a zinc oxide cake.

The water content of the obtained zinc oxide cake was:
It was as low as 31.4 to 34.4% by mass and stable.

Example 2 A dehydration treatment was performed in the same manner as in Example 1 except that a belt-type dehydrator (Super Filter, manufactured by TDE) was used as the second-stage dehydrator.

The water content of the obtained zinc oxide cake was 1
It was as low as 8 to 24% by mass and stable.

[0043]

As described above, in the conventional one-stage dehydration, if the concentration of the zinc oxide slurry to be dehydrated is unstable, the moisture content of the zinc oxide cake obtained after the dehydration is high, or While the operation in the drying and heating furnace became unstable, the production amount of zinc oxide ore and zinc oxide ore was reduced. Even if the slurry concentration of the zinc oxide slurry to be subjected to the second dehydration is unstable, the moisture content of the zinc oxide cake obtained by the second stage of the dehydration can be kept constant, and the zinc oxide ore or the zinc oxide ore can be removed. The amount of heat for manufacturing can be reduced.

Further, since the moisture content of the zinc oxide cake is stabilized, the operation in the drying and heating furnace is stabilized, and the effect of significantly improving the productivity of zinc oxide ore or zinc oxide ore can be obtained. it can.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a method for dewatering a zinc oxide slurry of the present invention.

FIG. 2 is a graph showing the relationship between the slurry concentration of a zinc oxide slurry and the water content of a zinc oxide cake after dehydration in Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solid-liquid separation equipment 2, 4 Dehydrator 3 Adjustment tank 3a Slurry concentration measuring device 3b Water volume adjusting device

Claims (1)

[Claims] (1) charging a steel dust containing zinc together with a reducing agent into a reduction roasting furnace to reduce the dust;
(2) performing a wet treatment on the crude zinc oxide recovered from the reduction roasting furnace, (3) performing a dehydration treatment on the obtained zinc oxide slurry, and (4) drying and heating the obtained zinc oxide cake. A zinc oxide ore or a zinc oxide ore comprising a step of charging into a furnace and firing, wherein the dehydration method in the wet treatment step comprises: (A) a first-stage dehydration step;
(B) In the zinc oxide cake obtained in the first-stage dehydration step,
A production method comprising: a step of adjusting the amount of addition so that the slurry concentration is constant, and adding adjustment water; and (C) a second-stage dehydration step.