US20120073405A1

US20120073405A1 - Dry processing method and system for converter slag in copper smelting

Info

Publication number: US20120073405A1
Application number: US13/105,514
Authority: US
Inventors: Takafumi Sasaki; Makoto Hamamoto; Takayoshi Fujii
Original assignee: Pan Pacific Copper Co Ltd
Current assignee: Pan Pacific Copper Co Ltd
Priority date: 2010-09-27
Filing date: 2011-05-11
Publication date: 2012-03-29
Also published as: CL2011001571A1; JP2012067375A

Abstract

The present invention provides a processing method for converting slag ejected from a converter in a copper smelting process to raw materials for iron manufacture. The processing method is for converter slag containing 1 mass % or more of Cu produced in a copper smelting process. The processing method comprises a step of charging the converter slag in a reduction furnace, and a step of conducting a heat reduction of a zinc content and a copper content contained in the slag and removing a reduced zinc by volatilization in the reduction furnace. The removal of the reduced zinc by volatilization is conducted in a condition in which an air fuel ratio of a volume of air blowing to an input of a reductant is controlled to 0.25 to 1.0.

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a dry processing method and system for slag ejected from a converter in a copper smelting. In particular, the present invention relates to a dry processing method and system for transferring slag ejected from a converter in a copper smelting to raw materials for iron manufacture.

BACKGROUND OF THE INVENTION

A general process of a copper smelting is as follows. An oxidation reaction of a copper concentrate which is a raw material is conducted in a flash smelting furnace, and about 68% copper grade of matte and a flash smelting furnace which contains iron oxide and silicate as a major constituent are produced and then separated. Next, the matte is fed into a converter, and about 99% copper grade of blister copper and a converter slag which contains silicic acid series iron oxide as a major constituent are produced and then separated. The blister copper is cast to anode of higher purity in an anode furnace, and the anode is subject to electrolytic refining and then electrolytic copper is produced.
On the other hand, with regard to the converter slag, slag floatation process, in which the converter slag is solidified and smashed and then a copper content is recovered by a flotation, is mainly employed (Journal of the Mining and Materials Processing Institute of Japan, “Mining and Materials Processing”, 1993. 12, Vol. 109, “nonferrous smelting issue”, page 954, 965; “Mining and Materials Processing”, 1997. 12, Vol. 113, “recycling feature issue”, page 996, left column, last paragraph). In the slag floatation process, slag copper concentrate of high copper grade (about 25% Cu) and iron concentrate of low copper grade (about 0.6% Cu) are separated, the copper concentrate can be processed repeatedly in the flash smelting furnace and the iron concentrate can be used mainly as cement raw material.
Further, Japanese Patent Application Laid-open Publication No. 53-22115 discloses a slag processing method in which copper oxide and Fe₃O₄contained in melt-state converter slag are reduced by adding a solid reductant such as coke and coal or a reductant such as gas and liquid to the slag, and then 1% or less copper grade of slag and blister copper are produced.
A recovery method for copper content in slag, in which magnetite in the slag is reduced by adding powdered coal to melt-state converter slag, put into practical use at CALETONES smelter of Codelco in Chile (Rolando Campos and Luis Torres, CALETONES SMELTER:TWO DECADES OF TECHNOLOGICAL IMPROVEMENTS, The Paul E. Queneau International Symposium, Ontario, CANADA (1993)).

(Patent documents 1) Japanese Patent Application Laid-open Publication No. 53-22115
(Nonpatent document 1) Journal of the Mining and Materials Processing Institute of Japan, “Mining and Materials Processing”, 1993. 12, Vol. 109, “nonferrous smelting issue”, page 954, 965
(Nonpatent document 2) “Mining and Materials Processing”, 1997. 12, Vol. 113, “recycling feature issue”, page 996, left column, last paragraph
(Nonpatent document 3) Rolando Campos and Luis Torres, CALETONES SMELTER:TWO DECADES OF TECHNOLOGICAL IMPROVEMENTS, The Paul E. Queneau International Symposium, Ontario, CANADA (1993)

SUMMARY OF THE INVENTION

Recently, Japanese cement market is on a shrinking trend and it is becoming difficult to retain customers using the iron concentrate produced by processing the converter slag with the slag floatation process disclosed in Patent document 1. Accordingly, a new application route for the converter slag is required. On this point, the converter slag may be used for raw materials for iron manufacture because it contains about 50 mass % of iron content. However, the converter slag contains about 4 mass % of copper content and about 2 mass % of zinc content. Accordingly, the copper grade and the zinc grade are too high for using the converter slag as the raw materials for iron manufacture. Even the iron concentrate produced in the slag floatation process contains about 0.6 mass % of copper content and about 2.5 mass % of zinc content. Accordingly, the copper grade and the zinc grade are still too high for using the iron concentrate as the raw materials for iron manufacture. It is desirable to maintain the copper content at 0.3 mass % or less and the zinc content at 1 mass % or less for use as the raw materials for iron manufacture. In the case of processing the converter slag by the methods of Nonpatent documents 1 to 3, the copper grade and the zinc grade are still so high that the converter slag is unsuitable for the raw materials for iron manufacture.
The present invention aims to provide a dry processing method and system for transforming slag ejected from a converter in a copper smelting to raw materials for iron manufacture.
The inventors have diligently studied to cope with the requirements, and eventually have found out a processing method for slag, in which a slag fuming process which is generally applied in zinc smelting is employed, an input of reductant in a reduction furnace is defined in a predetermined range, zinc is removed by volatilization from the slag, and on the other hand, copper is reduced, and then copper is precipitated to separate blister copper from the slag in a reduction furnace or in a settling furnace after moving the slag to the settling furnace arranged tandemly to the reduction furnace. The present method allows the converter slag to convert to a slag in which the copper grade and the zinc grade decrease to a utilizable level for the raw materials for iron manufacture. Further, the converter slag can be processed continuously by separating copper by precipitation not in the reduction furnace but in the settling furnace separately.
Generally in the slag fuming process, melt-state slag is reduced by heating and metals such as Zn, Pb and As in the slag are volatilized, and for example, a reduction furnace in a lance for gas injecting or a tuyere in a lower part of furnace is used. That is a process in which the metals in the slag are reduced and volatilized by jetting a reductant (for example, propane gas or heavy oil) and combustion air from an end of the lance or the tuyere to the slag charged in the furnace. The processed slag is discharged from a bottom part of furnace and the volatilized metals are recovered from a top part of furnace.
The slag fuming process is generally used in a slag processing in zinc smelting. However, the process is not conventionally used in the converter slag processing in the copper smelting like the present invention, and there is no such necessity. Accordingly, the present invention is highly characterized by applying the slag fuming process to the converter slag processing in the copper smelting. Further, in an embodiment in which the slag extracted from the reduction furnace is moved to the settling furnace and the reduced copper is separated by precipitation and recovered there, the converter slag can be processed continuously and it is extremely advantageous for real operations.
Therefore, in one aspect, the present invention is a processing method for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:
a step of charging the converter slag in a reduction furnace, and
a step of conducting a heat reduction of a zinc content and a copper content contained in the slag and removing a reduced zinc by volatilization in the reduction furnace, and
wherein the removal of the reduced zinc by volatilization is conducted in a condition in which an air fuel ratio of a volume of air blowing to an input of a reductant is controlled to 0.25 to 1.0.
In another aspect, the present invention is a processing method for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:
a step of charging the converter slag in a reduction furnace,
a step of conducting a heat reduction of a zinc content and a copper content contained in the slag and removing a reduced zinc by volatilization in the reduction furnace, and
a step of separating a reduced copper by a precipitation from the slag, and
wherein the removal of the reduced zinc by volatilization is conducted in a condition in which an air fuel ratio of a volume of air blowing to an input of a reductant is controlled to 0.25 to 1.0.
In yet another aspect, the present invention is a processing method for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:
a step of charging the converter slag in a reduction furnace,
a step of conducting a heat reduction of a zinc content and a copper content contained in the slag and removing a reduced zinc by volatilization in the reduction furnace,
a step of transferring a reduced copper with the slag from the reduction furnace to a settling furnace, and
a step of separating the reduced copper by a precipitation from the slag in the settling furnace, and
wherein the removal of the reduced zinc by volatilization is conducted in a condition in which an air fuel ratio of a volume of air blowing to an input of a reductant is controlled to 0.25 to 1.0.
In one embodiment, the present invention is the processing method wherein the converter slag is held in a melt state, and the converter slag is charged in the reduction furnace from a holding furnace for controlling a supply of the converter slag to be supplied to the reduction furnace.
In another embodiment, the present invention is the processing method further comprising a step of conducting a preliminary reduction of the converter slag before supplying to the reduction furnace.
In yet another embodiment, the present invention is the processing method wherein the preliminary reduction is conducted in the holding furnace.
In yet another embodiment, the present invention is the processing method further comprising a step of crushing the slag after the step of separating the reduced copper by a precipitation from the slag.
In yet another embodiment, the present invention is the processing method wherein Fe₃O₄contained in the slag is heat-reduced to FeO in the reduction furnace.
In yet another embodiment, the present invention is the processing method wherein the reductant is put in the slag flowing for the reduction furnace from the holding furnace.
In yet another embodiment, the present invention is the processing method wherein the reductant is put in the slag flowing for the holding furnace from the converter.
In yet another embodiment, the present invention is the processing method wherein the reductant used for the reduction of the slag in the reduction furnace is 1 to 10 mass % of coke to mass of the slag.
In yet another aspect, the present invention is a processing system for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:
a reduction furnace in which a heat reduction of a zinc content and a copper content contained in the converter slag is conducted,
an exhaust means installed in the reduction furnace for removing the volatilized reduced zinc,
a settling furnace for separating a reduced copper by a precipitation from the slag,
a transfer means for transferring the slag ejected from the reduction furnace to the settling furnace, and
a discharge means for discharging the reduced copper separated by a precipitation from the settling furnace, and
wherein the removal of the reduced zinc by volatilization is conducted in a condition in which an air fuel ratio of a volume of air blowing to an input of a reductant is controlled to 0.25 to 1.0.
In one embodiment, the present invention is the system further comprising a slag crush processing means and a transfer means for transferring the slag ejected from the reduction furnace to the slag crush processing means.
In yet another aspect, the present invention is a processing system for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:
a reduction furnace in which a heat reduction of a zinc content and a copper content contained in the converter slag is conducted,
an exhaust means installed in the reduction furnace for removing the volatilized reduced zinc,
a settling furnace for separating a reduced copper by a precipitation from the slag,
a transfer means for transferring the slag ejected from the reduction furnace to the settling furnace, and
a discharge means for discharging the reduced copper separated by a precipitation from the settling furnace, and
wherein the removal of the reduced zinc by volatilization is conducted in a condition in which an air fuel ratio of a volume of air blowing to an input of a reductant is controlled to 0.25 to 1.0.
In one embodiment, the present invention is the system further comprising a slag crush processing means and a transfer means for transferring the slag ejected from the settling furnace to the slag crush processing means.
In yet another embodiment, the present invention is the system further comprising:
a holding furnace for holding the converter slag in a melt state and controlling a supply of the converter slag to be supplied to the reduction furnace, and
a transfer means for transferring the converter slag ejected from the holding furnace to the reduction furnace.
In yet another embodiment, the present invention is the system further comprising a preliminary reduction furnace for conducting a preliminary reduction of the converter slag before supplying to the reduction furnace.
In yet another embodiment, the present invention is the system wherein the holding furnace doubles as the preliminary reduction furnace.

ADVANTAGEOUS EFFECT OF THE INVENTION

The present invention allows the converter slag to continuously convert to slag in which the copper grade and the zinc grade decrease to a utilizable level for the raw materials for iron manufacture. Further, the present invention allows copper recovery efficiency from the slag to increase.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 indicates a continuous processing system for converter slag in one embodiment of the present invention.

FIG. 2 indicates a batch processing system for converter slag in one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the processing method and the system for the converter slag of the present invention will be described with referent to FIGS. 1 and 2.
In general, in copper smelting process, a composition of slag ejected from a converter is 50 to 60 mass % of iron content (mainly as Fe₃O₄or FeO), 20 to 25 mass % of silicon content (mainly as SiO₂), 3 to 10 mass % of copper content (mainly as CuS, Cu₂O or CuO), 3 to 6 mass % of zinc content (mainly as ZnO) and 1 to 3 mass % of aluminum content (mainly as Al₂O₃). In addition, 1 to 5 mass % of Cu is generally contained by itself.
Accordingly, in the present invention, “converter slag” indicates not only slag actually ejected from the converter in copper smelting but also slag having a similar composition with converter slag in copper smelting. For example, about 3 to 5 mass % of raw minerals and Al₂O₃deriving from silicate minerals of solvent are contained in flash smelting furnace slag in copper smelting. Accordingly, alumina (Al₂O₃) grade is too high for using the slag as raw materials for iron manufacture. However, in the case that alumina grade is low in raw minerals, silicate minerals and flash smelter slag, the present invention can be applied.
Continuous Processing System
First, a continuous processing system for converter slag will be described. Referring to FIG. 1, the slag flowing in receiving gutter 1 from a converter (not shown) at melt state of 1200 to 1330° C. is guided to holding furnace 2 with maintenance of the melt state. The holding furnace 2 may be guided to the slag in a condition of not being melt state. For example, grained slag may be received in a hopper and then the slag may be guided to the holding furnace 2. The slag guided to the holding furnace 2 is held at melt state. The holding furnace 2 serves as controller of slag supply to the reduction furnace 4. For example, the holding furnace 2 supports a stable continuous operation of slag processing system by supplying constant flows of slag at all times to the reduction furnace 4.
The slag coming out of the holding furnace 2 goes through slag gutter 3 in melt state and are charged in the reduction furnace 4. Zinc content, copper content and other metal contents in the slag are reduced in the reduction furnace 4. Further, significant amount of magnetite (Fe₃O₄) is also contained in the slag and viscosity of the slag can be lowered by reducing the magnetite to FeO. When the viscosity of the slag is lowered, the reduced copper suspending in the slag is easy to separate by precipitation and copper recovery rate in next process increases.
Examples of reductant include, but are not limited to, carbonaceous solid reductant such as coke and coal, gas reductant such as hydrogen and hydrocarbon (methane, ethane, propane, butane and the like), liquid reductant such as petroleum and heavy oil. Typically, LPG can be used. It is preferable to use upper blowing method in which the reductant is jetted with combustion air to the slag charged in the reduction furnace 4 from an end of lance 5 set in from top part of furnace. This allows reaction efficiency of the slag and the reductant to increase because melting slag in the reduction furnace 4 can be strongly stirred. The end of the lance 5 may be immersed in the slag. The tuyere installed in the bottom part of furnace can be used for supplying the reductant. Further, the reaction efficiency can be increased by increasing guide flow volume of reductant and reduction time. That is, the zinc grade and the copper grade in the slag can be lowered.
In the reduction furnace 4, for example, when propane is used as the reductant, the following reduction reaction occurs:
10Cu₂O+C₃H₈→20Cu+3CO₂+4H₂O
10ZnO+C₃H₈→10Zn+3CO₂+4H₂O
10Fe₃O₄+C₃H₈→30FeO+3CO₂+4H₂O
Examples of reductant to reduce the slag in the reduction furnace 4 include, but are not limited to, heavy oil, LPG or coke. When coke is used, the input is preferably 1 to 10 mass % to the mass of the slag.
A volume of blowing to the input of the reductant to the reduction furnace 4 is controlled to an air fuel ratio of 0.25 to 1.0. Since a reduction reaction is an endothermic reaction, a temperature of the slag decreases when the reaction proceeds. It is necessary to compensating heat simultaneously with reduction so that the temperature of the slag may not drop. However, when the air fuel ratio is below 0.25, the compensating heat is short, the temperature of the slag drops, and then deterioration of flowability of the slag and separability of the slag with metals are caused. Further, for example, when the air fuel ratio is 0.5, 50% of the reductant burn with air and then it is used for the compensating heat, and the other 50% of the reductant is used for reduction of the slag. However, when the air fuel ratio is over 1.0, all of the reductant burn with air and its effect as reductant disappears.
When a reductant used in the reduction furnace 4 is coke, it may be put in the slag flowing from the holding furnace 2 to the reduction furnace. Specifically, it may be put in the slag gutter 3 shooting the slag from the holding furnace 2 to the reduction furnace 4. Further, it may be put in an out fall of the slag in the reduction furnace 4. This is because reduction efficiency of coke is low when the coke is put in on the slag in the reduction furnace 4, and then the coke is preferably put in as it is involved in the slag.
The reduced zinc is volatilized from a slag phase and ejected with other volatilized constituent or fine slag particles from gas duct 6 as slag fuming gas, and then guided to a plant for producing sulfuric acid. On the way to the gas duct to the plant for producing sulfuric acid, bag filter 7 is installed, which can recover zinc. Further, cooling water may be sprayed on the gas duct and a water-cooling tower (not shown) may be installed to lower a temperature of exhaust gas. The reduced zinc may be oxidized by air and the like on the way to the gas duct 6 and may be recovered by the bag filter 7 as zinc oxide. In general, lead is also contained in the slag fuming dust.
After the reduction reaction, the slag containing the reduced copper is ejected from the reduction furnace 4 and then guided through solution gutter 8 to settling furnace 9 with maintenance of the melt state. Then the reduced copper is separated by precipitation with difference in specific gravity from the slag. The separation by precipitation is conducted not in the reduction furnace 4 but in the settling furnace 9 installed separately, and then a continuous operation can be conducted. The efficiency of separation by precipitation can be increased and a copper grade in the slag can be lowered by lengthening a time for the separation by precipitation. Conversely, recovery efficiency of copper can be improved.
The reduced copper is discharged through the blister copper gutter 10 after the separation by precipitation. A copper grade of the reduced copper can be 40 to 80 mass % and the reduced copper can be returned to the converter. On the other hand, the slag, which the reduced copper is separated from, is transferred to the slag crush equipment 12 through the slag gutter 11, and then crushed to particle sizes that are easy to use. Examples of the crush equipment include, but are not limited to, a water crusher, crusher, a grinding mill, combinations thereof, and the like. Considering a production of raw materials for iron manufacture from the reduced slag, it is necessary to lower a Zn grade because blast furnace manufacturers have a restriction about the Zn grade. On the other hand, the Zn grade does not make any difference for electric furnace manufacturers, and some of the manufacturers can use it as a raw material when the Cu grade is lowered to 0.n % and its configuration is a massive form of 20 to 30 mm diameter. In this case, next of the step in the settling furnace needs to be not a step in the water crush equipment but a step of coagulation to a massive form and a crush processing.
By going through the above processes, the copper grade in the slag can be lowered to 0.3 mass % or less and the zinc grade in the slag can be lowered to 1 mass % or less. Therefore, the slag processed by the present invention can be used as raw materials for iron manufacture.
In the present embodiment, the converter slag can be processed continuously. Accordingly, during a continuous operation of the system, the reduction reaction and the removal of the reduced zinc by volatilization in the furnace, the separation of the reduced copper by precipitation in the settling furnace and the crush processing for the slag in the slag crush equipment can be conducted simultaneously.
Batch Processing System
Next, a batch processing system for the converter slag will be described. Referring to FIG. 2, the slag flowing in receiving gutter 1 from a converter (not shown) at melt state of 1200 to 1330° C. is charged in the reduction furnace 4 with maintenance of the melt state. Zinc content, copper content and other mental contents in the slag are reduced in the reduction furnace 4. Employable reductants and the reduction reaction in the reduction furnace 4 are the same as those of the continuous processing system. The recovery of the reduced zinc is also the same as that of the continuous processing system.
After the reduction reaction, the reduced copper is separated by precipitation in the reduction furnace 4. The reduced copper is discharged through the blister copper gutter 10 after the separation by precipitation. On the other hand, the slag, which the reduced copper is separated from, is transferred to the slag crush equipment 12 through the slag gutter 11, and then crushed to particle sizes that are easy to use. The processed slag can be used as raw materials for iron manufacture. The reduction furnace may be plurally installed in parallel.
In the present invention, a preliminary reduction furnace, which conducts a preliminary reduction of the converter slag before supplying to the reduction furnace 4, may be additionally installed. Thus, some of the copper oxide contained in the slag can be reduced and recovered by separation by the preliminary reduction of the converter slag before supplying to the reduction furnace 4. Accordingly, usage of the reductant in the reduction furnace can be decreased and then the equipment can be reduced. That is, a load of the reduction furnace can be reduced. The preliminary reduction is, but not limited to, preferably conducted so that copper grade can be 2.5 mass % or less and zinc grade can be 1.5 mass % or less in the converter slag. The preliminary reduction may be conducted at 1200 to 1300° C. The holding furnace 2 may double as the preliminary reduction furnace. In this case, existing equipments can be used effectively and then production cost can be favorable. Further, by the preliminary reduction with the holding furnace 2, variability of compositions with each batch in the converter slag can be reduced and then the composition of the slag charged in the reduction furnace 4 can be stabilized. Accordingly, an input of the reductant to the reduction furnace 4 and a primary amount of combustible air can be easily controlled. Examples of the reductant used in the preliminary reduction include, but are not limited to, solid reductants such as coke and coal. Using such solid reductants, the preliminary reduction can be conducted in the holding furnace 2. The reductant is put in to the holding furnace 2 in a manner such that coke or coal is put in to the melted slag, from the receiving gutter 1 used in transferring the slag from the converter, or in around an slag input slot to the holding furnace 2. Thus, by putting in the reductant to the melted slag, the reductant is well stirred with the slag and then put in to the holding furnace 2. Accordingly, it works well to the reduction reaction of the slag. Further, even though the reductant is put in large quantity, the reduction effect does not so good. Accordingly, for example, the input of the reductant is preferably 1 to 10% to mass of the converter slag. In addition, “primary amount of combustible air” indicates an amount of air for burning the reductant to compensating heat for those dropped in temperature by the reduction reaction of the slag.

EXAMPLES

Examples of the present invention will be described as follows, but the following examples are intended to be illustrative and non-limiting.

Example 1

Slag ejected from a converter of copper smelting was processed on the following conditions by a system described in FIG. 2.
converter slag: 10 ton
composition of converter slag: Shown at Table 1
input of heavy oil (reductant) to reduction furnace: 1438 L (basic unit 144 L/ton-slag)
primary amount of combustible air: 5586 Nm³(air fuel ratio 0.39)
slag reduction temperature: 1270° C.
composition of reduced slag: Shown at Table 2
settling time: 1 hour

TABLE 1

composition of converter slag (%)

Cu	Zn	Ni	Sn	Pb

2.10	1.93	0.15	0.42	0.53

TABLE 2

composition of reduced slag (%)

Cu	Zn	Ni	Sn	Pb

<0.3	0.82	0.08	0.22	0.07

Example 2

Slag processing similar to Example 1, in which composition of slag was different from that of the converter slag of Example 1 and only the air ratio w as changed, was conducted as Example 2.
converter slag: 7 ton
composition of converter slag: Shown at Table 3
input of heavy oil (reductant) to reduction furnace: 842 L (basic unit 120 L/ton-slag)
primary amount of combustible air: 5539 Nm³(air fuel ratio 0.66)
slag reduction temperature: 1270° C.
composition of reduced slag: Shown at Table 4
settling time: 1 hour

TABLE 3

composition of converter slag (%)

Cu	Zn	Ni	Sn	Pb

3.68	2.49	0.25	0.44	0.45

TABLE 4

composition of reduced slag (%)

Cu	Zn	Ni	Sn	Pb

<0.3	0.64	0.13	0.18	0.06

Example 3

Slag ejected from a converter of copper smelting was processed on the following conditions by a system described in FIG. 1. Further, a preliminary reduction was conducted in a holding furnace and then a converter slag was charged in a reduction furnace.
converter slag: 165 kg
composition of converter slag: Shown at Table 5
input of carbon material (preliminary reductant) to holding furnace: 2.2% to mass of converter slag
slag holding temperature: 1300° C.
composition of slag after holding: Shown at Table 6
input of heavy oil (reductant) to reduction furnace: 17 L (basic unit 100 L/ton-slag)
primary amount of combustible air: 60 Nm³(air fuel ratio 0.35)
slag reduction temperature: 1250° C.
composition of reduced slag: Shown at Table 7
settling time: 1 hour

TABLE 5

composition of converter slag (%)

Cu	Zn	Ni	Sn	Pb

6.98	1.63	0.23	0.02	0.35

TABLE 6

composition of slag after holding (%)

Cu	Zn	Ni	Sn	Pb

1.46	1.14	0.04	0.10	0.13

TABLE 7

composition of reduced slag (%)

Cu	Zn	Ni	Sn	Pb

<0.3	0.8	0.04	0.10	0.10

Reduced slags produced in Examples 1 to 3 are suitable for raw mate rials for iron manufacture for blast furnace manufacturers, and satisfy recent demand for Zn grade to reduced slag from blast furnace manufacturers. Especially, blast furnace manufacturers demand a rigorous specification being a level of 0.n % of Zn grade. The reduced slags of the present Examples satisfy the required level.

EXPLANATION OF REFERENCE NUMBERS

1 receiving gutter
2 holding furnace
3 slag gutter
4 reduction furnace
5 lance
6 gas duct
7 bag filter
8 solution gutter
9 settling furnace
10 blister copper gutter
11 slag gutter
12 slag crush equipment

Claims

1. A processing method for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:

a step of charging the converter slag in a reduction furnace, and

a step of conducting a heat reduction of a zinc content and a copper content contained in the slag and removing a reduced zinc by volatilization in the reduction furnace, and

wherein the removal of the reduced zinc by volatilization is conducted in a condition in which an air fuel ratio of a volume of air blowing to an input of a reductant is controlled to 0.25 to 1.0.

2. A processing method for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:

a step of charging the converter slag in a reduction furnace,

a step of separating a reduced copper by a precipitation from the slag, and

3. A processing method for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:

a step of charging the converter slag in a reduction furnace,

a step of conducting a heat reduction of a zinc content and a copper content contained in the slag and removing a reduced zinc by volatilization in the reduction furnace,

a step of transferring a reduced copper with the slag from the reduction furnace to a settling furnace, and

a step of separating the reduced copper by a precipitation from the slag in the settling furnace, and

4. The processing method of claim 1, wherein the converter slag is held in a melt state, and the converter slag is charged in the reduction furnace from a holding furnace for controlling a supply of the converter slag to be supplied to the reduction furnace.

5. The processing method of claim 1, further comprising a step of conducting a preliminary reduction of the converter slag before supplying to the reduction furnace.

6. The processing method of claim 5, wherein the preliminary reduction is conducted in the holding furnace.

7. The processing method of claim 1, further comprising a step of crushing the slag after the step of separating the reduced copper by a precipitation from the slag.

8. The processing method of claim 1, wherein Fe₃O₄contained in the slag is heat-reduced to FeO in the reduction furnace.

9. The processing method of claim 4, wherein the reductant is put in the slag flowing for the reduction furnace from the holding furnace.

10. The processing method of claim 4, wherein the reductant is put in the slag flowing for the holding furnace from the converter.

11. The processing method of claim 1, wherein the reductant used for the reduction of the slag in the reduction furnace is 1 to 10 mass % of coke to mass of the slag.

12. A processing system for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:

a reduction furnace in which a heat reduction of a zinc content and a copper content contained in the converter slag is conducted,

an exhaust means installed in the reduction furnace for removing the volatilized reduced zinc, and

a discharge means for discharging the reduced copper separated by a precipitation from the reduction furnace, and

13. The system of claim 12, further comprising a slag crush processing means and a transfer means for transferring the slag ejected from the reduction furnace to the slag crush processing means.

14. A processing system for converter slag containing 1 mass % or more of Cu produced in a copper smelting process, comprising:

an exhaust means installed in the reduction furnace for removing the volatilized reduced zinc,

a settling furnace for separating a reduced copper by a precipitation from the slag,

a transfer means for transferring the slag ejected from the reduction furnace to the settling furnace, and

a discharge means for discharging the reduced copper separated by a precipitation from the settling furnace, and

15. The system of claim 14, further comprising a slag crush processing means and a transfer means for transferring the slag ejected from the settling furnace to the slag crush processing means.

16. The system of claim 12, further comprising:

a holding furnace for holding the converter slag in a melt state and controlling a supply of the converter slag to be supplied to the reduction furnace, and

a transfer means for transferring the converter slag ejected from the holding furnace to the reduction furnace.

17. The system of claim 12, further comprising a preliminary reduction furnace for conducting a preliminary reduction of the converter slag before supplying to the reduction furnace.

18. The system of claim 17, wherein the holding furnace doubles as the preliminary reduction furnace.

19. The system of claim 14, further comprising:

20. The system of claim 14, further comprising a preliminary reduction furnace for conducting a preliminary reduction of the converter slag before supplying to the reduction furnace.