JPS62127432A - Method for recovering useful metal from dust discharged from metallurgical furnace for metal refining - Google Patents

Abstract

PURPOSE:To recover useful metals in high efficiency without wasting a reducing agent by providing the inner wall of a rotary kiln in the direction of length with plural annular dams so as to divide the kiln into two or more reducing atmosphere zones and one oxidizing atmosphere zone. CONSTITUTION:The rotary kiln 1 is provided, on the inner wall thereof, with the primary and the secondary intermediate dams 6, 7 to divide the inside of the kiln 1 into the primary and the secondary reducing atmosphere zones A, B and the oxidizing atmosphere zone C. A mixture of dust and solid carbonaceous reducing material is charged from an inlet 1a, which is passed through the primary reducing atmosphere zone A, stopped by the primary intermediate dam 6, and deposited. Subsequently, the above mixture overflows the primary intermediate dam 6, which is passed through the secondary reducing atmosphere zone B and then stopped by the secondary intermediate dam 7. As the result of the increase in the length of time required for the above movement, above-mentioned mixture is thoroughly dried and heated, so that zinc oxide, lead oxide, etc., are actively reduced and vaporized, and separated from the dust, which is fed into the oxidizing atmosphere zone C so as to reoxidize the reduced metals and to discharge them from an outlet 1b.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for efficiently and economically recovering useful metals such as zinc and lead from dust discharged from a metallurgical furnace for metal refining. It is something.

[Prior art and its problems]

For example, in an electric furnace for steelmaking, when manufacturing steel using steel scrap containing galvanized steel and crannog as raw materials, a large amount of dust generated during refining includes: 1. In addition to iron, zinc, It contains many useful metals such as lead. Disposing of such dust is not only extremely uneconomical in terms of effective use of resources, but also because the useful metals are hazardous substances, it is impossible to dispose of them as they are. This is a serious problem in terms of pollution.

For this reason, research has been conducted on methods for recovering useful metals such as zinc and lead from the dust emitted from metallurgical furnaces for metal refining, such as electric furnaces for steelmaking. The reduction and volatilization recovery method has been put into practical use.

As one of the reduction and volatilization recovery methods using a rotary kiln,
For example, Japanese Patent Publication No. 57-1999, filed by the present applicant, etc. 1
No. 4737 discloses a method consisting of:

The amount of electric furnace dust for steelmaking required to reduce the Fe2O3 contained in the dust to almost FeO, and the amount required to reduce the oxidized/crude lead and lead oxide contained in the dust. Charged into a rotary kiln together with a total amount of solid carbonaceous reducing agent equal to the total amount of the required amount and the amount required as a heat source for each of the above-mentioned reductions,
The dust and the reducing agent are moved toward the outlet of the rotary kiln, and the inside of the rotary kiln is made into an oxidizing atmosphere zone near the outlet and a reducing atmosphere zone elsewhere, and the burner provided at the outlet portion is used to reduce the oxidation increasing the temperature of the reducing atmosphere zone, and being in the reducing atmosphere zone;
Proximity to the oxidizing atmosphere zone is achieved by reducing Fe2O3 contained in the dust to F'eOK, reoxidizing FeO in the oxidizing atmosphere zone, and burning the reducing agent as a heat source. In this way, zinc oxide, lead oxide, etc. contained in the dust are reduced and vaporized in the high-temperature reducing atmosphere zone, and zinc, lead, etc. are separated from the dust. The zinc, lead, etc. thus separated are discharged from the rotary kiln together with the exhaust gas and recovered.

According to the above method, zinc contained in the dust,
Useful metals such as lead can be efficiently recovered.

However, in actual operation, the conventional method (1
The following problems were found. That is, the dust and solid carbonaceous reducing agent charged into the rotary kiln are moved from the inlet to the outlet by the rotation of the rotary kiln, which is inclined at a gradient of 2/100 to 3/100. This speed of movement is determined by the rotation speed of the rotary kiln and is constant everywhere from its population to its exit.

Therefore, the reaction between the dust and the reducing agent in the rotary kiln tends to be insufficient, and the reducing agent is discharged without being fully used for the reaction, resulting in a larger amount of reducing agent being consumed than necessary for the dust. This results in an increase in processing costs.

Additionally, in order to improve dust processing efficiency, increasing the amount of dust charged per unit time will shorten the time it takes for the dust to pass through the kiln if the rotation speed of the rotary kiln is constant, which will slow down the reduction reaction. This results in insufficient recovery efficiency of useful metals.

In order to increase the passage time of the dust and reducing agent in the kiln so that the reaction between the dust and the reducing agent takes place sufficiently, it is recommended to reduce the rotational speed of the kiln or use a large rotary kiln. However, reducing the rotational speed of the kiln greatly reduces the amount of dust to be processed, and on the other hand, installing a large rotary kiln requires a large amount of equipment and operating costs.

[Purpose of the invention]

Therefore, an object of the present invention is to extract useful metals such as zinc and lead from the dust discharged from a metallurgical furnace for metal refining without wasting solid carbonaceous reducing agents and without requiring a large rotary kiln. The objective is to provide a method for efficient and economical recovery.

[Summary of the Invention] The present invention is directed to treating dust discharged from a metallurgical furnace for metal refining, which mainly contains Fe2O3, ZnQ, and PbO, together with a solid carbonaceous reducing agent, into a reducing atmosphere zone that occupies most of the area including the inlet area. and an oxidizing atmosphere zone including an outlet portion, from the inlet of the rotary kiln, and moving through the rotary kiln from the inlet toward the outlet, and in the reducing atmosphere zone, the zinc oxide and dust in the dust are charged. A method for recovering useful metal from dust discharged from a full-bending smelting metallurgical furnace, in which lead oxide is reduced and vaporized by the reducing agent, and zinc and lead are separated and recovered from the dust, comprising: a length of the rotary kiln; At a predetermined interval in the direction,
By providing at least two ring-shaped dams on the inner wall of the rotary kiln, the inside of the rotary kiln is divided into at least two reducing atmosphere zones and one oxidizing atmosphere zone, and the inside of the rotary kiln is divided into at least two reducing atmosphere zones and one oxidizing atmosphere zone. The present invention is characterized in that the movement of the dust and the reducing agent is temporarily dammed by the at least two ring-shaped dams, thereby keeping the movement time longer than K, thereby improving the reduction efficiency of zinc oxide and lead oxide in the dust. It is.

[Structure of the invention]

Next, the method of the present invention will be explained with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of a rotary kiln used in the method of the present invention, and FIG. 2 is a sectional view taken along the line a-a in FIG. 1. As shown in the drawing, the rotary kiln 1 is installed with an inclination of, for example, 3/100, and a chute 2 for charging dust and solid carbonaceous reducing agent is arranged in its population 1a, and its outlet In 1b, a gunner 3 is arranged horizontally toward the inside of the rotary kiln.

A ring-shaped inlet dam 4 is provided on the inner wall of the inlet 1a of the rotary kiln, and a ring-shaped outlet dam 5 is provided on the inner wall of the outlet lb. Approximately 3 of the total length of rotary kiln l from inlet 1a of rotary kiln 1
A ring-shaped first intermediate dam 6 is provided on the inner wall of the rotary kiln l.
A ring-shaped second intermediate dam 7 is provided on the inner wall at a position approximately two-thirds of the total length of the rotary kiln l from a.

In this way, the rotary kiln 1 has a first reducing atmosphere zone A between the inlet dam 4 and the first intermediate dam 6.
, the period from the first intermediate dam 6 to the second intermediate dam 7 is the second
The area between the second intermediate dam 6 and the outlet dam 5 is divided into a reducing atmosphere zone B, and an oxidizing atmosphere zone C between the second intermediate dam 6 and the outlet dam 5.

The temperature inside the rotary kiln 1 is the first reducing atmosphere zone A.
The temperature is maintained at about 650° C. or less in the second reducing atmosphere zone B, and rises to about 1200° C. in the oxidizing atmosphere zone C, and is controlled to rise rapidly to about 120' cm in the oxidizing atmosphere zone C.

A mixture of dust and solid carbonaceous reducing agent, which is continuously charged into the rotary kiln 1 from the inlet 1a by the charging chute 2, passes through the first reducing atmosphere zone A in the rotary kiln 1 toward the outlet 1b. Move to the first intermediate dam 6
It is dammed up until it reaches the height of the first intermediate dam 6. In this way, when the mixture deposited in the first reducing atmosphere zone A exceeds the height of the first intermediate dam 6,
The mixture moves into a second reducing atmosphere zone B.

As mentioned above, when the charging amount of the mixture charged into the rotary kiln 1 per unit time and the amount of the mixture overflowing the first intermediate dam 6 per unit time become approximately constant. is the maximum deposition rate of the mixture in the first atmospheric zone A.

Since the mixture in the rotary kiln I moves spirally while being stirred up and down due to its rotation, the movement time of the mixture in the first reducing atmosphere zone A is increased by the damming of the first intermediate dam 6 mentioned above. do.

The temperature in the first reducing atmosphere zone A is controlled to be low so that the temperature near the first intermediate dam 6 is 500 to 650°C. Therefore, the mixture of dust and solid carbonaceous reducing agent is
The increase in transfer time described above ensures sufficient drying and heating to the temperature required for the reduction reaction. In this way, since the first reducing atmosphere zone A (τ1 low 7 crystals is on the 't+lI side 1), the reduction of iron oxide in the dust by the solid carbonaceous reducing agent 1 is suppressed. C. The consumption of the reducing agent in the first reducing atmosphere zone A is small, and the reducing agent is consumed in the second reducing atmosphere zone A, which will be described later.
It can be efficiently used for reducing zinc oxide, lead oxide, etc. in the reducing atmosphere zone B.

The mixture of dust and solid carbonaceous reducing agent in the second elemental atmosphere zone B moves in the second reducing atmosphere zone B toward the outlet 1b, as in the first reducing atmosphere zone A described above. and moves to the second intermediate dam 7, and the second intermediate dam 7
It is dammed up and accumulated until it reaches a height of , and when it exceeds the height of the second intermediate dam 7, it moves into the oxidizing atmosphere zone C. Therefore, by blocking the second intermediate dam 7 mentioned above, the second
The travel time within the counterfeit atmosphere zone B increases.

The temperature in the second reducing atmosphere zone B is controlled so as to rapidly rise to a high temperature of about 1200'C near the second intermediate dam 7. Therefore, in the high temperature portion of the second reducing atmosphere zone B, zinc oxide, lead oxide, etc. contained in the dust are actively reduced and vaporized and separated from the dust. In this way, zinc, lead, etc. separated from Cust are re-oxidized by oxygen present in the space inside the rotor kiln, becoming zinc oxide and lead oxide again, and enter the rotary kiln 1 together with the exhaust gas. 1a and collected by a dust collector. On the other hand, in the second reducing atmosphere zone B, Fe2O3 contained in the dust becomes Fe0
It is reduced by Kt.

The above-mentioned reaction is carried out very efficiently due to the increase in the movement time of the mixture of dust and solid carbonaceous reducing agent in the second reducing atmosphere zone B, and the solid carbonaceous reducing agent is effective for the above-mentioned reaction. consumed.

The temperature in the oxidizing atmosphere zone C is maintained at the outlet 1b by a burner 3 arranged horizontally toward the interior of the o-tally kiln 1.
The reduced FeO in the second reducing atmosphere zone B is reoxidized. The oxidation heat generated at this time is also added, and the temperature in the oxidizing atmosphere zone C is 1
The temperature rises rapidly to over 200°C. As a result, the temperature of the second reducing atmosphere zone B in the vicinity of the oxidizing atmosphere zone C is increased, and the reductive vaporization of zinc oxide, lead oxide, etc. described above is promoted.

Fe2O3 re-oxidized in the oxidizing atmosphere zone C becomes a talin car together with the residue in the dust, and is discharged from the outlet 1b of the rotary kiln 1.

Next, we used the following test rotary kiln, which is 1/1000th the scale of an actual furnace, to monitor the movement of dust inside the furnace.

il+ Length: 2400 m1 (2) Diameter: 280 meters (3) Slope: 3/100 (4) Location of the first intermediate dam 850 cranes from the second population (
5) Position of second intermediate dam: 900 meters from the first intermediate dam (6) Height of intermediate dam -30 degrees (7) Number of rotations: 1. ORPM Test dust with a particle size of 1 to 4 mm is supplied to the above rotary kiln at an amount of 100 no/H (equivalent to 6 T/H of an actual furnace), and the supply amount and the discharge from the rotary kiln are the same amount. From the point at which the temperature reached an equilibrium state, colored dust having a particle size of 1 to 4 m was supplied into the rotary kiln in an amount of 1 ooy/= for 1 minute.

Then, the time from the charging of the test dust and colored dust to the start of discharge, the peak time of discharge of colored dust, etc. were investigated.

For comparison, a test rotary kiln of the same scale as above was used, except that the first and second intermediate dams were not installed, and the time from charging the test dust and colored dust to the start of discharge was calculated in the same manner as above. , and the amount of discharge of colored dust and the start time.

3 and 4 are graphs showing the results of the above investigation, in which FIG. 3 shows the case where an intermediate dam is provided, and FIG. 4 shows the case where many intermediate dams are provided. As shown in Figure 3, when an intermediate dam is provided, the time a from charging the test dust to starting discharging is 102 minutes, and the time from charging colored dust to starting discharging is 55 minutes. Yes, and
The time C from the charging of the colored dust until the discharge amount reached its peak was 120 minutes.

On the other hand, as shown in Figure 4, the time a from charging the test dust to starting discharging when no intermediate dam is provided.
' is 47 minutes, the time b' from charging the colored dust to the start of discharge is 33 minutes, and the time C' from charging the test dust until the discharge amount of colored dust reaches its peak is 65 minutes. It was a minute.

As is clear from the above, the time from charging the test dust to the start of discharging when an intermediate dam is installed is more than twice that when the intermediate dam is not installed, and the color change when an intermediate dam is installed The time from charging the dust to the start of discharge and the time from charging the colored dust to the peak discharge amount were about twice as long as when no intermediate dam was provided. Furthermore, when examining the test dust accumulation 1 in the rotary kiln, it was found that it was 6.7 to 9 when no intermediate dam was installed, but 1 when an intermediate dam was installed.
1.6 to 9, and about 1.7 without an intermediate dam.
It was double that.

Figure 5 shows that when test dust and colored dust of 200y/cut (equivalent to 12T/H of an actual furnace) are supplied in the same manner as above to the rotary kiln equipped with an intermediate dam, Figure 6 shows that The time from charging the test dust and colored dust to the start of discharge, and the colored This is the result of investigating the peak time of dust emissions.

As shown in Figure 5, when an intermediate dam is installed,
The time a from the charging of the test dust to the start of discharge is 65 minutes, the time from charging the colored dust to the start of discharge is 43 minutes, and the amount of discharge from the charging of the colored dust reaches its peak. The time C required for this to occur was 73 minutes.

On the other hand, as shown in Fig. 6, the time a from charging the test dust to starting discharging when no intermediate dam is provided.
' is 36 minutes, the time b' from charging the colored dust to the start of discharge is 26 minutes, and the time C' from charging the colored dust until the discharge amount reaches its peak is 5 minutes.
It was 5 minutes.

As is clear from the above, the time from the charging of test dust to the start of discharge when an intermediate dam is provided is approximately 1.8 times that when no intermediate dam is provided; The time from the charging of colored dust to the start of discharge is approximately 1.6 times that of the case without an intermediate dam, and the time from charging of colored dust to the peak discharge amount is approximately 1.6 times that of the case without an intermediate dam. It was .3 times as large. Furthermore, when we investigated the amount of test dust accumulated in the rotary kiln, we found that it was 14.8 kg when an intermediate dam was installed, compared to 11.1 kg when no intermediate dam was installed, and about 1 kg when no intermediate dam was installed. It was .3 times as large.

From the above, it can be seen that, as in the present invention, the first
．． It is clear that by providing the second intermediate dam, the time for the dust to travel through the rotary kiln, ie the dust accumulation 1, is increased, thereby improving the dust treatment efficiency.

[Embodiments of the invention]

Next, the present invention will be explained with reference to examples. Steelmaking electric furnace dust having the composition shown in Table 1 was granulated into particles with a particle size of about 101 LI using a granulator7, and then dried to form 3+4 particles of dust pellets.

The above-mentioned dust pellets and a solid carbonaceous reducing agent consisting of coke and coal are combined into a length of 24,000 mm as shown in FIG.
IIB, and charged into a rotary kiln 1 having an inner diameter of 28001B. In the rotary kiln 1, a ring-shaped first intermediate dam 6 with a height of 300 cm is installed on the inner periphery of the position from population 1a to 850011B, and a ring-shaped first intermediate dam 6 with a height of A ring-shaped second intermediate dam 7 with a length of 300 nm was provided.

The charging amount of dust pellets is 6,000 to 7,0OOKq.
/H, and the charging amount of solid carbonaceous reducing agent is 570 to 66
It is 5Kg/H.

At the outlet 1b of rotary kiln l, rotary kiln l
28 to 30 kg of kerosene per tonne of dust was blown into the rotary kiln 1 along with air from a gunner 3 installed toward the inside of the rotary kiln and burned.

The quality of one item in rotary kill/l is 1. First return light? 'i
:, l; 630 "CIJ, bottom, control, 2nd return F", 'jF'/;I'll feel LB near 1111 dam 7 in the second middle of LB -) at 1200'C ＾・“
1.
The temperature was rapidly increased to above 200°Cμ.

As a result, in the first reducing atmosphere zone A +, the dust was sufficiently dried and heated, and in the second reducing atmosphere zone B, the zinc oxide and lead oxide contained in the dust were etc. were reduced and vaporized and separated from the dust in the evening and recovered.The Fe2O3 in the dust was reduced to F'eO at a rate of 1. And in an oxidizing atmosphere; ;7C Fe
O is reoxidized to Fe2O3, and the high temperature heat of oxidation generated at that time increases the temperature of the second reducing atmosphere zone B in the vicinity of the oxidizing atmosphere zone C. was discharged from the outlet 1b as a clinker containing

The amount of dust containing zinc oxide and lead oxide recovered was 1500.
~1800Kg/H, and its component composition is as shown in Table 2.

Table 3 shows the amount of solid carbonaceous reducing agent used per ton of dust and the amount of dust processed per lm'' per day in the method of the present invention and the conventional method without an intermediate dam. and product recovery rate. Figure 7 shows the change in the amount of solid carbonaceous reducing agent used (K9/T), Figure 8 shows the change in the amount of dust processed (T/D/m"), and Figure 9 shows the change in the amount of dust processed (T/D/m"). It is a graph showing each change in product recovery rate (section).

As is clear from Table 3 and Figures 7 to 9 above, according to the method of the present invention, the amount of solid carbonaceous reducing agent used is reduced to 15/9/T compared to the conventional method, and the amount of dust treated is reduced compared to the conventional method. The increase was approximately 0.37 T/D/rrl.

The product recovery rate varied depending on the Zn concentration in the dust (15 to 20 inches), but it increased by about 4 inches from 23 to 27, as is clear from FIGS. 3 and 9.

In the above description, two intermediate dams are provided in the length direction of the rotary kiln, but the number is not limited to two, and three or more may be provided.

〔Effect of the invention〕

As described above, according to the present invention, useful metals such as zinc and lead can be efficiently and economically extracted from dust discharged from metallurgical furnaces using a smaller amount of solid carbonaceous reducing agent than in the past. This provides an excellent industrial effect that can be recovered in a timely manner.

[Brief explanation of drawings]

Fig. 1 is a schematic vertical cross-sectional view of a rotary kiln used in the method of the present invention, Fig. 2 is a cross-sectional view taken along the line a-& in Fig. 1, and Figs. 3 to 6 show dust retention in the a-tary kiln. FIG. 7 is a graph showing the change in the amount of solid carbonaceous reducing agent used, FIG. 8 is a graph showing the change in the amount of dust treated, and FIG. 9 is a graph showing the change in the product recovery rate. In the drawing, ■...Rotary kiln, 1a...
・Inlet, lb...outlet, 2...chute, 3...burner, 4...inlet dam, 5...
...Exit dam, 6...First intermediate dam, 7...
・Second intermediate dam. Figure 1 Diagram 2 Figure 3 Guan Figure 4 Discharge time (mtx) Figure 5 Oni Figure 6 Discharge time (VAN) Figure 7 layer also Figure 8 House Figure 9 Procedure amendment (voluntary) 1986 4 May 188, Michibe Uga, Commissioner of the Japan Patent Office1, Indication of the Case, Patent Application No. 1988-263895, Title of the Invention, Relationship with the case of usefulness from dust discharged from a metallurgical furnace for metal refining Patent applicant: Tokyo; Chiyoda-ku Marunouchi 1-1-2 Ie(L)
4) Nippon Steel Tube Co., Ltd. Representative: Form Yamashiro (and 1 other person) 4. Agent address: Half mFi+'lZ! IjR, Todoroki FAF11. :, M
Il+l! tNl? 'b5cl? 6. Subject of correction
ゝ-・Claims of the specification, detailed explanation of the invention, brief explanation of drawings, drawing 7, content of amendments As attached (1) Specification The width of the special rods of the moss is as follows: Correct it as follows. [Mainly Fe2 discharged from metallurgical T for metal and end wires
Together with dusty gold containing O3, ZnO and pBO, and a solid carbonaceous reducing agent, a rotary kiln is formed from the inlet into a rotary kiln consisting of a oxidizing atmosphere zone which occupies most of the inlet area containing the gold, and an oxidizing atmosphere zone which includes the outlet part. The dust is charged and moved through the rotary kiln from the inlet to the outlet, and in the reducing atmosphere zone, lead oxide and lead oxide in the dust are reduced and vaporized by the reducing agent, and zinc and lead are removed. Separating and recovering gold from the dust [41] In a method for recovering all useful metals from the dust discharged from a metallurgical furnace,
By providing at least two ring-shaped dams on the inner wall of the rotary kiln, the inside of the rotary kiln is divided into at least two reducing atmosphere zones and one oxidizing atmosphere zone, and the inside of the rotary kiln is divided into at least two reducing atmosphere zones and one oxidizing atmosphere zone. By temporarily blocking the movement of the dust and the reducing agent by the at least two ring-shaped dams, the movement time of the dust and the reducing agent is kept longer, and thus the oxidized lead and lead oxide in the dust are reduced. A method for recovering useful metals from dust discharged from a metallurgical furnace for metal refining, characterized by increasing reduction efficiency. (2) Specification, Section 3, Detailed Description of the Invention, Line 3, ``Generated during the city division'' is corrected to ``Generated from the steelmaking electrical equipment during refining.'' . (3) Specification, page 7, Detailed description of the invention, bottom line, ``By this, in the dust'', ``By this, the dust and the reduction "It keeps the migration time of the agent long and thus in the dust." (4) In the specification, page 8, Detailed Description of the Invention, line 7, the phrase "a-a line sectional view" is corrected to "11-I line sectional view." (5) Specification, page 9, Detailed Description of the Invention, line 8, "Second Intermediate Dam 6" is corrected to "Den 2 Intermediate Dam 7." (6) Specification, Section 24, Brief Description of Drawings, Section 1;
'/, lines a to 7, "cross-sectional view taken along line a-a," should be corrected to read "cross-sectional view taken along line 11-I." (7) In the drawings, Figure 1 is corrected as shown in the attached sheet. Attached is 1 or more copies of 1F Ken's inventory correction drawings.

Claims (1)

[Claims] Mainly Fe_2O discharged from a metallurgical furnace for metal refining
_3. Dust containing ZnO and PbO, together with a solid carbonaceous reducing agent, is charged from the inlet into a rotary kiln consisting of a reducing atmosphere zone that occupies most of the area including the inlet area, and an oxidizing atmosphere zone that includes the outlet area. The dust is moved inside the rotary kiln from the inlet to the outlet, and in the reducing atmosphere zone, zinc oxide and lead oxide in the dust are reduced and vaporized by the reducing agent, and the zinc and lead are removed from the dust. In a method for recovering useful metals from dust discharged from a metallurgical furnace for metal refining, the method includes: separating and recovering useful metals from dust discharged from a metallurgical furnace for metal refining;
By providing at least two ring-shaped dams on the inner wall of the rotary kiln, the inside of the rotary kiln is divided into at least two reducing atmosphere zones and one oxidizing atmosphere zone, and the at least two reducing atmosphere zones The movement of the dust and the reducing agent in the dust is temporarily stopped by the at least two ring-shaped dams, thereby keeping the movement time long and improving the efficiency of reducing zinc oxide and lead oxide in the dust. A method for recovering useful metals from dust discharged from a metallurgical furnace for metal refining.