JP2023103823A - Method for manufacturing crude zinc oxide, and flue cinder treatment method - Google Patents

Abstract

To provide a method for manufacturing a crude zinc oxide using steel dust as a raw material which can effectively utilize flue cinder containing zinc and copper produced in a copper refining furnace as a part of a raw material, while avoiding mixing the copper into a reduced iron pellet that is a by-product and is available as an iron source.SOLUTION: A method for manufacturing a crude zinc oxide includes a reducing and roasting step ST21 of reducing and roasting steel dust, and obtaining crude zinc oxide dust, a wet step ST22 of subjecting the crude zinc oxide dust to wet treatment, and obtaining a crude zinc oxide cake, and a drying and heating step ST23 of firing the crude zinc oxide cake, and obtaining a crude zinc oxide sintered mine, wherein the drying and heating step ST23 fires flue cinder produced and collected in a copper refining furnace, together with the crude zinc oxide cake.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing crude zinc oxide and a method for treating flue ash. More specifically, the present invention relates to a method for producing crude zinc oxide from a raw material containing flue generated in a copper smelting furnace, and a method for treating flue containing zinc and copper generated in a copper smelting furnace.

Flue dust collected from exhaust gas generated in a copper smelting furnace contains a large amount of zinc, bismuth, etc., which are easily volatilized, in addition to copper contained in copper concentrates. In general, the flue dust generated in the copper smelting process is repeatedly processed into the copper smelting furnace again because it contains metals for smelting purposes.

However, since the above flue dust contains bismuth, if this is repeated in the copper smelting furnace, the quality of impurities such as bismuth in the copper anode obtained in the copper smelting process will increase, and the next copper refining process (electrolytic process) ), the problem of an increase in the impurity grade of the electrolytic copper obtained becomes apparent.

Regarding this problem, Patent Document 1 discloses that flue dust containing a high concentration of lead generated and recovered in non-ferrous metal smelting is mixed with iron and steel dust containing chlorine as mixed pellets, and then used in a crude zinc oxide production process. A method is disclosed for treating flue ash by subjecting it to a reduction roasting process in a manner similar to the method for treating steel dust with a conventional reduction roasting process.

Here, steel dust is often used as a raw material in the production of crude zinc oxide. The reduced iron pellets obtained as a by-product in the process of reducing and roasting the iron and steel dust are recycled as an iron source again by steel manufacturers. However, when the flue ash processed in the reduction roasting process as described above contains "copper" in particular, this copper is distributed to the reduced iron pellets, which poses a new problem. . This is because "copper" is one of the impurities that steel manufacturers using reduced iron pellets have most severely restricted their inclusion in iron sources.

JP 2013-139618 A

In the production of crude zinc oxide using iron and steel dust as a raw material, the present invention contains zinc and copper generated in a copper smelting furnace while avoiding copper from being mixed into reduced iron pellets that are by-products and can be used as an iron source. An object of the present invention is to provide a method for producing zinc oxide, which can effectively utilize flue ash generated as part of raw materials.

The present inventors have found that flue ash, which was conventionally put into the reduction heating process, which is the upstream process in the production process of crude zinc oxide, together with steel dust, which is the primary raw material, is used as a secondary raw material, which is the downstream process, drying. The inventors have conceived that the above problems can be solved by adopting a process in which they are directly introduced into the heating step, and have completed the present invention. The present invention specifically provides the following.

(1) A reduction roasting step of obtaining crude zinc oxide dust by reduction roasting of iron and steel dust, a wet treatment of said crude zinc oxide dust to obtain a crude zinc oxide cake, and said crude zinc oxide. a dry heating step of baking a cake to obtain a crude zinc oxide calcined ore, wherein in the dry heating step, together with the crude zinc oxide cake, generated in a copper smelting furnace A method for producing crude zinc oxide by burning the flue ash collected by

According to the method for producing crude zinc oxide in (1), in the production of crude zinc oxide using steel dust as a raw material, copper can be effectively used as part of the raw material. Therefore, when the reduced iron pellets are shipped as an iron source for iron manufacturers, the possibility of postponing the shipment due to the high copper grade can be greatly reduced.

(2) a reduction roasting step of reducing and roasting steel dust to obtain crude zinc oxide dust; a wet step of subjecting the crude zinc oxide dust to a wet treatment to obtain a crude zinc oxide cake; and the crude zinc oxide. a dry heating step of baking a cake to obtain a crude zinc oxide calcined ore, wherein zinc and copper are contained together with the crude zinc oxide cake in the dry heating step. A method for producing crude zinc oxide, which comprises burning smoke ash having a copper content of 10% or more.

According to the method for producing crude zinc oxide in (2), even when flue ash containing zinc and copper, particularly with a high copper content, is used as a raw material at a crude zinc oxide production site, it is a by-product and an iron source. Copper-containing flue dust can be effectively utilized as part of the raw material while avoiding copper contamination of available reduced iron pellets.

(3) The method for producing crude zinc oxide according to (1), wherein the copper smelting furnace is a copper smelting converter.

According to the method for producing crude zinc oxide of (3), in the method of producing crude zinc oxide described in (1), lead, zinc, bismuth, etc., which volatilize and scatter from the melt and have a relatively low boiling point, Lead, zinc, and bismuth can be recovered more efficiently by using flue ash generated in a copper smelting converter, which contains a large amount of them.

(4) The method for producing crude zinc oxide according to any one of (1) to (3), wherein the flue dust has a lead content of 12% or more and a zinc content of 4% or more.

According to the method for producing crude zinc oxide of (4), in the method of producing crude zinc oxide according to any one of (1) to (3), the target metals, zinc and copper, and lead are added at high concentrations. Zinc and copper, as well as lead, can be recovered more efficiently by using the flue ash contained in .

(5) A flue ash treatment method for treating flue ash recovered from a copper smelting furnace and having a lead content of 12% or more, wherein the flue ash is dry-heated in a crude zinc oxide production process. A flue ash treatment method used as a secondary raw material to be introduced into the process.

According to the flue ash treatment method of (5), flue ash generated in a copper smelting furnace and containing a high concentration of lead is used as a by-product and iron source in the production of crude zinc oxide using steel dust as a raw material. Copper can be effectively utilized while avoiding copper contamination in available reduced iron pellets. Therefore, when the reduced iron pellets are shipped as an iron source for iron manufacturers, the possibility of postponing the shipment due to the high copper grade can be greatly reduced. In addition, since flue ash is treated in the drying and heating process, there is no need to go through the reduction roasting process and the wet process, which are upstream processes, and the cost of flue ash treatment can be reduced by reducing the number of processes. can.

According to the present invention, in the production of crude zinc oxide using iron and steel dust as a raw material, while avoiding copper from being mixed into reduced iron pellets that are a by-product and can be used as an iron source, flue containing copper is used as a raw material. It can be used effectively as a part.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing the flow of the method for producing crude zinc oxide according to the present invention using flue dust generated in copper smelting as a secondary raw material.

Preferred embodiments of the present invention will be described below with reference to the drawings as appropriate. FIG. 1 is a flow chart showing the flow of the method for producing crude zinc oxide according to the present invention using flue dust generated in copper smelting as part of the raw material.

<Method for producing crude zinc oxide>
In the method for producing crude zinc oxide of the present invention, iron and steel dust containing zinc generated from blast furnaces, electric furnaces, etc. in the steel industry is used as a raw material, impurities are removed from the raw material, and the zinc grade is 65% as a raw material for product zinc. It is a process for producing crude zinc oxide of the order of magnitude.

The method for producing crude zinc oxide of the present invention is a process for carrying out the conventionally known crude zinc oxide producing process P2 whose basic flow is shown in FIG. In the method for producing crude zinc oxide according to the present invention, the basic flow of steps is the same as the conventional method shown in FIG.

However, the method for producing crude zinc oxide of the present invention, as shown in FIG. (also referred to as "zinc- and copper-containing flue dust") is directly introduced into the drying and heating step ST23, which is one step downstream of the crude zinc oxide production process P2, as part of the secondary raw material. It is a process with a new feature that is different from

According to the present invention, by introducing the "zinc-copper-containing smoke dust" generated in copper smelting into the dry heating step ST23 in the crude zinc oxide production process P2, copper is produced into reduced iron pellets that are a by-product and can be used as an iron source. It is an excellent method for producing crude zinc oxide in that zinc can be recovered at a high recovery rate while avoiding the contamination of , and the flue dust can be effectively used as a secondary raw material.

In addition, according to the present invention, "zinc- and copper-containing flue dust" generated in copper smelting can be treated at low cost in existing facilities without investing in new facilities such as rotary kilns for the existing crude zinc oxide production process. It is also an excellent flue dust disposal method in that it can be used.

<Copper smelting process P1>
The copper smelting process P1, which is the supply source of the "zinc-copper-containing smoke dust" used as a secondary raw material in the method for producing crude zinc oxide of the present invention, obtains blister copper with a copper grade of about 98% from the copper concentrate and finally obtains It is a process to obtain electrolytic copper. In the copper smelting process P1, generally, a copper concentrate, which is a raw material for copper smelting, is first treated in a flash furnace to be separated into matte and slag with a copper grade of around 60%. The matte obtained here is sent to the converter process provided next, and becomes blister copper having a copper grade of about 98% in the converter. After that, the blister copper is refined to a copper grade of about 99% in a refining furnace provided next, and cast as an anode for treatment in the refining process provided next. In the refining process, electrolytic copper is obtained from this anode.

Flue ash having different compositions and properties is generated in the flash furnace, converter, and refining furnace described above. Flue ash generated in a flash furnace is flash smelting, so it contains carry-over of concentrates and the like, and has a high copper grade. In addition, the amount of flue ash generated in the refining furnace is very small. On the other hand, flue ash generated in a converter is bath smelting and contains a large amount of relatively low boiling points such as lead, zinc, and bismuth that evaporate and scatter from the melt. Therefore, in the method for producing crude zinc oxide of the present invention, the "zinc/copper-containing flue dust" that is part of the raw material (or the "zinc-copper-containing flue dust" to be treated by the method for treating flue dust of the present invention) is Among the various flue dusts mentioned above, it is particularly preferable to use the flue dust with high lead and zinc grade obtained from a converter. Alternatively, in the method for producing crude zinc oxide of the present invention, the flue ash generated in the converter of the copper smelting process (herein also referred to as "copper smelting converter") is repeatedly treated in the copper smelting process. It is also possible to use flue ash with increased lead and zinc grades, which is obtained after sintering.

Further, in the method for producing crude zinc oxide of the present invention, the "zinc/copper-containing flue dust" (or the "zinc-copper-containing flue dust" to be treated by the flue dust treatment method of the present invention) used as part of the raw materials is , contains zinc and copper, and exhibits a more significant advantage over the prior art when the copper content is 10% or more. In the past, when using flue dust with a high copper content, there was a risk of hindering recycling as an iron source due to the copper component being mixed into the reduced iron pellets. By avoiding the treatment of flue dust in the process and concentrating the flue dust treatment after the downstream drying and heating process, such a risk can be completely avoided.

In the method for producing crude zinc oxide or the method for treating flue dust of the present invention, the "zinc-copper-containing flue dust" should have a lead content of 12% or more and a zinc content of 4% or more. is preferred. Flue dust containing a high concentration of lead volatilizes again even if it is repeatedly processed at the site of copper smelting, resulting in a large increase in the amount of material circulating in the process. On the other hand, by introducing such "zinc-copper-containing smoke dust" having a high lead content into the production method and treatment method of the present invention, the production process of crude zinc oxide and the subsequent production of lead-zinc can be achieved. Lead and zinc as well as copper can be recovered more efficiently in the process.

<Crude zinc oxide production process P2>
The crude zinc oxide production process P2 is a process in which a reduction roasting step ST21, a wet process ST22, and a drying heating step ST23, which will be described in detail below, are sequentially performed.

[Reduction roasting step ST21]
In the reduction roasting step ST21, primary raw materials such as iron and steel dust are roasted in a reducing atmosphere by selecting an appropriate temperature and residence time, thereby reducing and volatilizing zinc, lead, etc., separating them, and further reoxidizing them. This is a step of obtaining crude zinc oxide dust. On the other hand, this process also recovers the iron as solid reduced iron pellets. A rotary kiln can be suitably used as the reduction roasting furnace for this step.

[Wet process ST22]
In the wet process ST22, the crude zinc oxide dust, which is re-oxidized through the reduction roasting process ST21 and contains zinc oxide and lead oxide, is further subjected to wet treatment to remove other residual impurities such as chlorine and fluorine, thereby obtaining crude oxidation. It is a process to obtain a zinc dehydrated cake (also referred to herein as a "crude zinc oxide cake"). The wet process ST22 can be performed using a conventionally known method.

[Drying and heating step ST23]
The drying and heating step ST23 is a step of baking the crude zinc oxide cake that has undergone the wet process ST22 to obtain crude zinc oxide calcined ore. Through this process, a crude zinc oxide calcined ore (also referred to herein as a "crude zinc oxide calcined ore") having a zinc grade of about 65% can be obtained.

The drying and heating step ST23 uses a rotary kiln, and charges raw zinc oxide cake and other secondary raw materials from the charging end of the rotary kiln. A burner is provided on the discharge end side of the rotary kiln, and this burner dries, heats, and calcines the raw material in the rotary kiln, and the crude zinc oxide calcined at about 800 to 900°C is produced on the discharge end side. obtain.

In the method for producing crude zinc oxide of the present invention, the above-mentioned copper-containing flue ash used as part of the raw material is fed to this drying and heating step ST23 as part of the secondary raw material.

In treating flue ash, the grades of copper, tin, and bismuth, which are abundant in flue ash, in the crude zinc oxide obtained are predicted from the impurity balance, and are further downstream of the crude zinc oxide manufacturing process. Determine the amount of flue ash to be processed so that it is within the process standards on the premise that it will be recovered in the decopperization process of the lead and zinc smelting that has been established. In addition, the crude zinc oxide obtained in the drying and heating step ST23 is also analyzed at a certain frequency to confirm that it is within the above criteria.

In addition, if the above-mentioned flue ash is put into the drying and heating process as it is, it will be carried over together with the dust generated by the transportation equipment and the exhaust gas from the rotary kiln, and will be carried over to the perforated plate of the flue and washing tower that are continuously provided in the rotary kiln. Adhesion, blocking these. Therefore, in order to avoid this, it is necessary to granulate the flue dust in advance into a pellet form, or to prepare sediment (water content 20% to 50%) other than the dehydrated cake processed in the drying and heating process in advance. It is preferable to knead and process the raw material and the loader.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example]
A test operation for producing zinc oxide was carried out according to the flow shown in FIG. As the flue ash used as part of the secondary raw material, flue ash generated in a converter in a copper smelting plant and recovered was used. The composition of this smoke ash was as shown in Table 1 below. In the drying and heating step, 1 t/day of the smoke dust and 170 t/day of crude zinc oxide cake were dried and heated at a temperature of 800° C. to 900° C. to obtain crude zinc oxide calcined ore. The crude zinc oxide calcined ore had a copper grade of 0.21%, a tin grade of 0.09%, and a bismuth grade of 0.10%, and was shipped as a raw material for smelting lead and zinc. Copper, tin, and bismuth were separated and recovered in the decoppering step of lead/zinc smelting, which follows the production of crude zinc oxide. In the reduction roasting process, 200 t/day of iron and steel dust is reduced and roasted at a temperature of 1100° C. to 1200° C. to obtain crude zinc oxide dust containing zinc oxide and reduced iron pellets, which are iron sources for iron manufacturers. shipped as

[Comparative example]
A test operation was performed under the same conditions as in the example, except that the flue ash was put into the reduction roasting process together with raw materials such as steel dust in the same manner as in the conventional process. In the reduction roasting step, 1 t/day of the smoke dust and 200 t/day of steel dust were reduced and roasted at a temperature of 1100° C. to 1200° C. to obtain crude zinc oxide dust containing zinc oxide and reduced iron pellets. The reduced iron pellets had a copper grade of 0.46%, a tin grade of 0.053%, and a bismuth grade of 0.092%.

According to the method for producing crude zinc oxide of the present invention, it is possible to greatly reduce the cost required for treating flue containing zinc and copper generated in copper smelting by using existing processes and equipment. In addition, since it is possible to prevent adverse effects of copper on existing processes, it is possible to maintain the quality of reduced iron pellets in existing crude zinc oxide production operations. It can be seen that lead can be recovered with a high recovery rate.

P1 Copper smelting process P2 Crude zinc oxide production process ST21 Reduction roasting process ST22 Wet process ST23 Dry heating process

Claims (5)

a reduction roasting step of reducing and roasting steel dust to obtain crude zinc oxide dust;
a wet process of subjecting the crude zinc oxide dust to a wet process to obtain a crude zinc oxide cake;
a drying and heating step of calcining the crude zinc oxide cake to obtain a crude zinc oxide calcined ore;
A method for producing crude zinc oxide, comprising
In the drying and heating step, together with the crude zinc oxide cake, the flue ash generated and recovered in the copper smelting furnace is burned.
A method for producing crude zinc oxide. a reduction roasting step of reducing and roasting steel dust to obtain crude zinc oxide dust;
a wet process of subjecting the crude zinc oxide dust to a wet process to obtain a crude zinc oxide cake;
a drying and heating step of calcining the crude zinc oxide cake to obtain a crude zinc oxide calcined ore;
A method for producing crude zinc oxide, comprising
In the drying and heating step, together with the crude zinc oxide cake, burn ash containing zinc and copper and having a copper content of 10% or more.
A method for producing crude zinc oxide. The copper smelting furnace is a copper smelting converter,
The method for producing crude zinc oxide according to claim 1. The smoke dust has a lead content of 12% or more and a zinc content of 4% or more.
The method for producing crude zinc oxide according to any one of claims 1 to 3. A flue ash treatment method for treating flue ash generated and recovered in a copper smelting furnace and having a lead content of 12% or more,
A method for treating flue ash, wherein the flue ash is used as a secondary raw material to be introduced into the drying and heating step in the crude zinc oxide manufacturing process.

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