JP2861479B2 - Zinc smelting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a smelting method for zinc using zinc sulfide concentrate, and more particularly to a smelting method for producing smoke ash which can be leached with dilute sulfuric acid to obtain a leachate which can be used as an electrolyte. .

[0002]

2. Description of the Related Art Currently, zinc smelting methods are roughly classified into a wet method and a dry method.

[0003] In the world, the wet method is the mainstream. In this wet method, zinc sulfide concentrate is oxidized and roasted in a fluidized roasting furnace as a slurry to obtain a calcined ore containing zinc oxide.
Then, in order to prevent the leaching of iron as much as possible, the calcined ore is leached with dilute sulfuric acid to obtain a zinc sulfate solution. Is removed to obtain a zinc electrolyte, and electrolysis is performed using an insoluble anode to obtain electric zinc.

However, in the above method, a zinc concentrate containing a large amount of lead is partially melted during the roasting because a fluidized roasting furnace is used in the roasting step. Therefore, fluidization in the roasting furnace becomes difficult, and there is a disadvantage that desulfurization does not proceed sufficiently, so that treatment cannot be performed.

Further, zinc ferrite (ZnFe ₂ O ₄ ) formed in this step does not dissolve in the leaching step, and accounts for more than 10 to 20% by weight (hereinafter, referred to as “%”) of the amount of zinc in the calcined ore. Zinc remains in the leaching residue and only low yields are obtained.

Further, a method of recovering Zn from this residue has been studied, and although the jarosite method and the hematite method have been developed, the treatment of the deposits generated by this treatment is indispensable for pollution control, and the cost is low. Includes the problem of pushing up.

Further, in order to remove the above-mentioned impurities from the leaching solution obtained from the leaching process, a multi-stage cleaning process is required, and high-purity arsenous acid is required as a cleaning agent.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to treat various kinds of zinc sulfide concentrates, and to remove leached traces of iron, copper, nickel and cobalt by removing leached iron. To provide a zinc smelting method that can simplify the process for the zinc smelting.

[0009]

In order to solve such problems, the zinc smelting method of the present invention comprises a raw material containing iron sulfide, zinc sulfide and a gangue component, and a raw material containing silicic acid and lime. Reacting the flux with a reactive gas containing oxygen to generate Zn vapor, FeO and SO ₂ ,
At a temperature of 1200 ° C. or higher, a molten slag containing at least iron oxide and silicic acid and having a sulfur grade of 0.3 to 15% is produced. Then, FeO and the gangue component in the raw material are separated into the molten slag, and the Zn vapor is brought into contact with the oxidizing air to form ZnO, so that most of the zinc in the raw material mainly consists of zinc oxide. Collected as smoke,
The smoke ash is dissolved with sulfuric acid to form a zinc sulfate solution, and the zinc sulfate solution is electrolyzed to recover zinc as metallic zinc.

In the zinc smelting method of the present invention, the reactive gas is
A type selected from the group consisting of industrial oxygen, oxygen-enriched air, and air, including oxygen required to oxidize iron sulfide in the raw material to FeO and SO _2, and oxygen required to burn fuel .

Further, heavy oil and pulverized coal as auxiliary fuel are mixed with the raw material and the flux as required.

Further, at least one of silica-based and lime-based oxides is used as a flux, Fe / SiO ₂ in the molten slag is set to 0.6 to 2.0, and CaO is set to 2
Adjust to 0% or less.

[0013]

According to the present invention, a raw material and a reaction gas are blown into a furnace at 1200 ° C. or higher to oxidize easily oxidizable iron sulfide in the raw material into FeO and SO _2, and to convert FeO together with gangue in the raw material into slag. And And ZnS, which is harder to oxidize than iron sulfide
Is decomposed into Zn vapor and sulfur vapor, and the vapor is mixed with a new reaction gas to convert the Zn vapor and sulfur vapor into ZnO and SO ₂ , respectively, and collect ZnO as smoke.

In the method of the present invention, the composition of the slag produced is based on the ZnS-ZnO-FeO-SiO ₂ system. And copper, nickel, cobalt, etc. contained in a raw material melt | dissolve in slag.

In the present invention, the reason why the slag temperature is set to 1200 ° C. or more is not only to secure the fluidity of the slag, but also to prevent deterioration of the flammability of the raw material in the furnace and to prevent undissolved substances in the furnace. This is for preventing generation in a large amount.

The reason why the S grade in the slag is maintained at 0.3% or more is to suppress the precipitation of Fe ₃ O ₄ which causes the furnace bottom to rise. Conversely, the reason why the S grade in the slag is set to 15% or less is that if the S grade becomes higher, the distribution rate of zinc in the slag increases, and the amount collected as smoke ash is greatly reduced. is there.

The reason why the ratio of Fe / SiO _{2 in} the slag is set to 0.6 to 2.0 is that the ratio of Fe / SiO _{2 which} causes the bottom of the slag is raised.
_This is for suppressing the precipitation of ₃ O ₄ .

Further, the reason why the CaO of the slag is set to 20% or less is that if added at this ratio, the melting temperature of the slag decreases, and the amount of Fe ₃ O ₄ dissolved in the slag can be increased. On the contrary, if it exceeds 20%, the melting point of the slag increases.

In addition, CaO has the effect of reducing the zinc content dissolved in the slag with a carbonaceous reducing agent, increasing the activity of Zn when volatilizing and recovering.

When Pb is contained in the concentrate, Pb is usually used.
Although present as S, this PbS has a high vapor pressure at 1200 ° C. or higher and evaporates similarly to Zn.

The vapors of Zn and Pb come into contact with the reaction gas and the oxidizing air supplied in a separate system, so that ZnO or PbSO
Generate ₄ .

The position for supplying the oxidizing air in this separate system may be in the furnace or in the flue gas duct, if it is behind the reaction position between the raw material and the reaction gas and before the smoke ash recovery facility. However, for example, when blowing into the furnace, it is desirable to blow in parallel so as not to hit the slag layer.

The amount of oxygen in the reaction gas to be blown is an amount necessary to convert at least Zn, S, and Pb in the gas into oxides and sulfates, respectively.

The generated exhaust gas containing ZnO, SO ₂ , and PbSO ₄ passes through a waste heat boiler, and then is subjected to an electric dust collector.
Or passed through a back filter or the like, Kemurihai and SO ₂
Separate from gas.

In the present invention, whether air, oxygen-enriched air, or industrial oxygen is used as the reaction gas depends on the SO ₂ concentration in the generated exhaust gas, in other words, the exclusion of SO ₂ gas. Depends on method and equipment capacity.

The smoke ash recovered in this way is ZnO
Or PbSO ₄ is mainly used, but by dissolving in dilute sulfuric acid, lead can be precipitated and removed as lead sulfate, and a zinc sulfate solution for zinc electrolysis can be obtained. A method for recovering electrolytic zinc from the obtained zinc sulfate solution is based on a conventional method.

[0027]

The present invention will be further described below with reference to examples.

First, a test smelting furnace for performing the zinc refining method of the present invention will be described.

The test smelting furnace shown in FIG. 1 has a height of 2.8.
m, a reaction tower 10 having an inner diameter of 1.5 m and a settler 20 having a length of 5.25 m and an inner diameter of 1.5 m. One end of the settler 20 is connected to the reaction tower 10, and the other end is connected to the flue duct 22. ing.

A blowing lance 15 having a diameter of 25 cm is inserted from above the reaction tower 10. Blow lance 15
Is connected to an oxygen source mixer 16, which is connected to a source feeder 18.

The opposite side walls of the settler 20 include:
An oxygen / heavy oil burner 24 and a heat retaining heavy oil burner 25 are provided.

Further, a slag hole 28 is provided below the heat retaining heavy oil burner 25 so that the slag 30 can flow out.

Example 1 Using the raw materials having the compositions shown in Table 1, a test was conducted in the test smelting furnace shown in FIG. 1 under the conditions of Example 1 in Table 2.

[0034]

[Table 1]

[0035]

[Table 2] *: Injection from the reaction tower (oxygen / heavy oil burner) side **: Injection from the slag hole (heat insulation heavy oil burner) side

In the test, Zn concentrate, flux, auxiliary fuel and reaction air were first blown into the reaction tower 10 from the top of the reaction tower 10 in the same manner as in a normal flash smelting furnace, and the molten slag was discharged. Manufactured.

Next, as shown in FIG. 1, the lance 15 was set so that the blowing port 15a of the blowing lance 15 was located at a position 300 mm from the upper surface of the slag, and Zn concentrate and flux were blown into the slag from the lance 15. The concentrate and the flux were mixed with the auxiliary fuel and the reaction air in the oxygen raw material mixer 16.

The heat required for dissolving the concentrate and the heat dissipated from the settler or the like were compensated for by using the fuel oil burner 26 and the oxygen / fuel oil burner 24 installed on the side walls of the settler 20 opposite to each other. .

The flow rate of free air was adjusted as a reaction gas for oxidizing metal components and sulfur in the exhaust gas.

The results obtained are shown in Example 1 of Table 3.

According to Table 3, the smoke ash obtained in Example 1 was F
It can be seen that e and Cu grades were low, and Fe and Cu were almost distributed in the slag.

[0042]

[Table 3]

Example 2 A test was performed in the same manner as in Example 1 under the conditions shown in Example 2 in Table 2.

Example 2 differs from Example 1 in that oxygen
Air for oxidizing metal components and sulfur in the gas is blown into the settler 20 from the side of the reaction tower where the heavy oil burner 24 is provided.

The results obtained are shown in Example 2 of Table 3.

Table 3 shows that the S grade and the Zn grade in the slag obtained under the conditions of Example 2 are low. This indicates an improvement in the volatility of Zn.

Although the magnetite in the slag is slightly increased, there is no operational problem.

Example 3 A test was performed in the same manner as in Example 1 under the conditions of Example 3 in Table 2.

In the third embodiment, the reaction air for oxidizing the metal components and sulfur in the gas is supplied to the heat retaining heavy oil burner 2.
6 was blown into the furnace from the side wall of the slag hole where it was installed. The obtained results are shown in Example 3 of Table 3.

From the results in Table 3, it can be seen that the volatilization rate of Zn is the highest in Example 3, and that the smoke ash obtained has good Zn quality. However, in Example 3, the amount of magnetite in the slag was increased, and this increase in magnetite was linked to the rise of the hearth, and it was obvious that the operation would eventually be stopped.

Example 4 500 g each of the smoke ash obtained in Examples 1, 2 and 3 was added to a 0.5N sulfuric acid solution in 11 containers, and the mixture was stirred while maintaining the liquid temperature at 50 to 60 ° C. , Dissolved and leached Zn.

The resulting slurry was filtered to obtain a leachate. The Zn concentration of each leachate is 100-120 g /
l.

Next, Zn powder was added to each leachate to adjust the Zn concentration to 130 g / l and the free sulfuric acid concentration to 15 g / l.
It was adjusted to 0 g / l to obtain an electrolytic solution. And Pb-Ag
Using the alloy electrode as an anode and the Al plate as a cathode, Zn in the electrolytic solution was electrolytically sampled.

The purity of the obtained electrodeposit was 4-5N.

[0055]

According to the method of the present invention, as described above, the impurities such as Fe and Cu are small, and the smoke ash mainly containing ZnO (including PbSO ₄ when the raw material contains lead) is produced. By leaching this with dilute sulfuric acid, a leachate that can be used as an electrolyte as it is is obtained. For this reason, separation of impurities from the leachate, which has conventionally been complicated, becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a smelting furnace of a bath smelting method used in an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 18 raw material feeding equipment 16 oxygen raw material mixer 10 reaction tower 20 settler 24 oxygen / heavy oil burner 26 heavy oil burner 28 slag hall

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C22B 19/32 C22B 19/34 C25C 1/16

Claims (6)

(57) [Claims] A raw material containing iron sulfide, zinc sulfide, and gangue components, a flux containing silicic acid and lime, and a reactive gas containing oxygen react with Zn vapor and Fe.
O and SO ₂ are generated, at a temperature of 1200 ° C. or more, containing at least iron oxide and silicic acid, and having a sulfur grade of 0.1.
3-15% of molten slag is produced, and FeO and the gangue component in the raw material are separated into the molten slag, while Z
n vapor is brought into contact with oxidizing air to form ZnO, thereby recovering most of zinc in the raw material as fumes mainly composed of zinc oxide, and dissolving the fumes with sulfuric acid to form a zinc sulfate solution; A zinc smelting method in which zinc is electrolyzed to recover zinc as metallic zinc. 2. The reactive gas is one selected from the group consisting of industrial oxygen, oxygen-enriched air, and air, and oxygen required to oxidize iron sulfide in the raw material to FeO and SO ₂ ; The zinc smelting method according to claim 1, further comprising oxygen necessary for burning the fuel. 3. The zinc smelting method according to claim 1, wherein an auxiliary fuel of heavy oil and pulverized coal is mixed with the raw material and the flux. 4. Use of at least one of a silica-based and a lime-based oxide as a flux,
/ SiO ₂ as 0.6 to 2.0, zinc smelting process of claim 1 wherein 20% or less of CaO. 5. A raw material containing iron sulfide, zinc sulfide, and gangue components, a flux containing silicic acid and lime, and a reactive gas containing oxygen, thereby reacting Zn vapor with Fe.
O and SO ₂ are generated and at a temperature of 1200 ° C. or more, containing at least iron oxide and silicic acid, and containing 20% of CaO.
In the following, a molten slag having a sulfur grade of 15% or less is produced, FeO and gangue components in the raw material are separated into the molten slag, and Zn vapor is brought into contact with oxidizing air to produce Zn.
O, most of the zinc in the raw material is recovered as fumes mainly composed of zinc oxide, and the fumes are dissolved in sulfuric acid to form a zinc sulfate solution, and the zinc sulfate solution is electrolyzed to convert zinc into metallic zinc. Zinc smelting method to recover as. 6. The reactive gas is one selected from the group consisting of industrial oxygen, oxygen-enriched air, and air, and oxygen required to oxidize iron sulfide in the raw material to FeO and SO ₂ . The zinc smelting method according to claim 5, further comprising oxygen necessary for burning the fuel.