KR20100088309A - Method for recovering metal zinc from material containing zinc - Google Patents

Abstract

PURPOSE: A method for recovering metal zinc from a zinc-containing material is provided to improve zinc recovery rate by keeping the temperature of a zinc recovery unit lower than that of a vaporizing unit. CONSTITUTION: A method for recovering metal zinc from a zinc-containing material comprises the steps of: forming a vaporizing unit(11) and a zinc recovery unit(12) which are connected or closed to let vaporized zinc flow, heading the zinc-containing material in non-oxidizing gas atmosphere in the vaporizing unit so as to vaporize zinc, and collecting the vaporized zinc by the zinc recovery unit, wherein the temperature of the zinc recovery unit is lower than the temperature of the vaporizing unit.

Description

Method for Recovering Metal Zinc from Material Containing Zinc}

The present invention relates to a method for recovering metal zinc from zinc-containing products, such as by-products containing zinc, more specifically, by providing a temperature difference to the evaporation section and the zinc recovery section and applying an electric field under appropriate conditions. Economically and more simply, a method for recovering metal zinc from zinc content.

In general, the method of smelting zinc is roughly divided into dry and wet methods, and dry methods are classified into horizontal distillation method, vertical distillation method, electrothermal distillation method, and electrothermal furnace method according to the type of furnace and heating source. Vertical vertical distillation method or electrothermal distillation method which has a commercialization is commercially operated.

Zinc-containing raw materials used in these methods are mainly composed of zinc-containing dust emitted from the steel industry (EU Pat. 0889141, (1991)).

Meanwhile, in recent years, antirust has been strengthened in the automobile industry, and the use of galvanized steel for most steel sheets constituting the vehicle body has led to a rapid increase in the amount of scrap of galvanized steel sheet, which has attracted attention for its efficient recycling.

The galvanized steel sheet can be effectively reused as a cast iron steel sheet because the steel plate under the plating layer is high purity steel close to pure iron, but when reused, a large amount of zinc material is generated in the melting process, especially a low frequency melting furnace, and zinc penetrates into the furnace wall. This causes the coil to short-circuit, short-circuits the coil, and significantly lowers the life of the furnace walls.

If this problem is not solved, the galvanized steel sheet is a low grade steel scrap and can only be used as an iron scrap for converter steelmaking, causing a great loss in terms of iron resource recycling.

In order to solve this problem, methods to remove and recover zinc before the galvanized sheet melting process have been proposed.

Typical examples are extraction methods for dissolving and removing with acids such as sulfuric acid (Japanese Patent Publication No. Hei 5-9607), electrolytic methods for electrolytic removal in alkaline solutions (US 005106467), and evaporation methods for heating and heating the steel sheet to evaporate zinc (Japan). Japanese Patent Application Laid-Open No. 5-70855, Japanese Patent Application Laid-Open No. 5-148552, Japanese Patent Application Laid-Open No. 5-125458, Japanese Patent Application Laid-Open 2006-37146, EU Pat. 0566451).

The extraction method and the electrolytic method are wet methods using acid and alkali, and have a problem in that waste water is generated to cause further operation of waste water treatment facilities and secondary environmental pollution problems.

On the other hand, since the evaporation method does not use water, and the steel scrap left after zinc recovery is heated to a high temperature, it has an advantage of saving energy when directly used as an iron source for casting.

As a method for recovering zinc by the evaporation method, a zinc-plated steel sheet charged into a rotary furnace is heated and oxidized with an oxygen-combustible burner to be recovered as zinc oxide powder in a dust collector, which is a subsequent device (Korean Patent Publication No. 1993-0021804, EP 0566451A1) has been proposed.

In addition, a reducing material is added to zinc-containing steel dust, and chlorine is first removed by heating in an atmospheric atmosphere, and then lead and zinc are sequentially recovered by secondary and tertiary heating under a 0.001-20 torr vacuum atmosphere. Is also proposed.

In addition, a method of heating and evaporating a galvanized steel scrap under vacuum and sucking the evaporated zinc to the cooling condenser side by a vacuum pump to condense and recover metal zinc (Japanese Patent Application Laid-Open No. 5-70855), non-oxidizing properties in an external rotary kiln A method of heating and evaporating under a gas atmosphere in which carbon monoxide (CO) and carbon dioxide (CO ₂ ) are mixed at an appropriate ratio as a gas (Japanese Patent Application Laid-Open No. Hei 5-125458). In addition, a method of recovering zinc by introducing methanol during the heating and inducing a reducing atmosphere with carbon monoxide and hydrogen, which are decomposition products of methanol, has also been proposed.

The common process of the distillation methods to recover in the form of metal zinc proposed above is to evaporate zinc by heating the steel sheet by a heating source under a non-oxidizing gas atmosphere or a vacuum under moderate pressure to prevent oxidation of the evaporated zinc. Zinc is guided to the top or side of the reactor by a vacuum pump, and the induced evaporated zinc gas is condensed in a cooling condenser and recovered in molten zinc form or recovered through a water-cooled recoverer.

As described above, the zinc recovered in the form of molten zinc is discharged out of the system at a necessary time, cast into a predetermined shape, and recycled into various raw and subsidiary materials.

At this time, the cooling condenser recovering the evaporated gas has a complicated structure in which molten metal zinc, which is maintained at a constant temperature, is splashed by a rotary rotor and contacted with vapor phase zinc to condense.

The conventional method for recovering zinc by the evaporation method described above is complicated because it adopts a method of introducing a non-oxidizing gas under a suitable vacuum condition and using a specially designed cooling condenser, that is, a method of recovering by splashing molten metal zinc. In addition to this, additional equipment such as a vacuum pump is required to maintain proper vacuum conditions, and the process is not only complicated, but also zinc recovery by contact with splashed molten zinc metal. Some of the evaporated zinc has a problem that is obtained in the form of zinc powder in the post-condenser process.

The present invention is a method for recovering metal zinc by heating and evaporating a zinc-containing product by applying a temperature difference to the evaporation unit and the zinc recovery unit and applying an electric field to the appropriate conditions, more efficient, more economical and simpler zinc-containing To provide a method for recovering the metal zinc from, the purpose is.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is a method for recovering metal zinc by heating and evaporating a zinc-containing,

Heating the zinc content to evaporate zinc, and a zinc recovery part for recovering the evaporated zinc, comprising: communicating with each other so that the vaporized zinc can communicate with each other and forming a closed system;

Evaporating zinc by heating the zinc content in a non-oxidizing gas atmosphere in the evaporator; And

Recovering zinc evaporated as described above in the zinc recovery unit;

The temperature of the zinc recovery portion is lower than the temperature of the evaporation portion, and during the evaporation and recovery of zinc, the zinc-containing material, characterized in that to add a (+) electric field to the evaporation part and a (-) electric field to the zinc recovery part To recover zinc from

As described above, the present invention maintains the atmosphere of the evaporation section and the zinc recovery section in a non-oxidizing gas atmosphere, applies an electric field to the evaporation section and the zinc recovery section under appropriate conditions, and maintains the temperature of the zinc recovery section below the temperature of the evaporation section. By doing so, not only can the metal zinc recovery rate be significantly improved, but it is also more economical and can greatly simplify the apparatus structure of the zinc recovery process.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for recovering metal zinc by heating and evaporating a zinc content, comprising: an evaporation part for heating a zinc content to evaporate zinc and a zinc recovery part for recovering evaporated zinc, so that the evaporated zinc can communicate. Communicating with each other and comprising a closed system.

An example of a zinc recovery apparatus constructed in accordance with the present invention is shown in FIG. 1.

As shown in FIG. 1, the zinc recovery device 10 includes an evaporator 11 for evaporating zinc by heating a zinc-containing material 1, a zinc recovery part 12 for recovering evaporated zinc, and an evaporator ( 11) and an electric field applying device 14 for applying an electric field to the zinc recovery unit 12.

The evaporation unit 11 is provided with a reaction vessel 111 for receiving the zinc-containing (1), the reaction vessel 111 may not be provided depending on the shape of the zinc-containing (1). .

The evaporation unit 11 includes a heating source 112 for heating and evaporating zinc-containing materials and a non-oxidizing gas supply pipe 113 for supplying non-oxidizing gas into the evaporation unit 11. .

The bottom of the reaction vessel 111 is formed with one to a plurality of holes smaller than the size of the zinc containing.

The zinc recovery unit 12 has a zinc recovery plate 121 and a cooling unit 122 for cooling zinc, a non-oxidizing gas outlet pipe 123 for circulating non-oxidizing gas, and a circulating coolant therein. Cooling water circulation pipe 124 is included.

The evaporation unit 11 and the zinc recovery unit 12 are connected by the connection unit 13 in the communication relationship of the evaporated zinc, it is configured to form a closed system (closed system).

In Fig. 1, reference numeral 2 denotes a moving direction of evaporated zinc gas and non-oxidizing gas, and 3 denotes condensed and recovered metal zinc.

In the zinc recovery apparatus of FIG. 1, the evaporation unit is disposed above and below the zinc recovery unit, but the present invention is not limited thereto. For example, the evaporation unit and the zinc recovery unit may be horizontally disposed or evaporated below. In addition, the zinc recovery portion may be placed on the top.

However, as shown in FIG. 1, the evaporation unit and the zinc recovery unit are preferably disposed such that the evaporation unit is disposed above and the zinc recovery unit is disposed up and down.

For example, if a zinc recovery unit is formed on the upper side of the evaporation unit, a condenser of a special structure capable of temperature control should be employed to recover zinc condensed in a relatively low temperature region.

The temperature of the zinc recovery portion is lower than the temperature of the evaporation portion, and

During the evaporation and recovery of zinc, a positive electric field is applied to the evaporation part and a negative electric field to the zinc recovery part.

The evaporated zinc moves and condenses the zinc vapor by the driving force caused by the temperature difference in the closed system.

The relatively high partial pressure zinc gas evaporated and expanded by the high temperature heating in the evaporator is moved to the low temperature portion, that is, the zinc recovery portion having a relatively low partial pressure, in order to reach a dynamic equilibrium state.

In the present invention, the temperature of the zinc recovery unit is sufficient to be lower than the temperature of the evaporation unit, but it is preferable to control the temperature of the zinc recovery unit to be 50 ° C or more lower than the temperature of the evaporation unit.

On the other hand, in the present invention, in order to recover the zinc vapor evaporated in the evaporator more efficiently in the zinc recovery unit, an electric field is applied to the evaporator and the zinc recovery unit, respectively.

That is, a positive electric field is applied to the evaporation part and a negative electric field is applied to the zinc recovery part.

The strength of the applied electric field is sufficient if it is specified in consideration of the electrostatic attraction that causes the vaporized zinc vapor to have (+) electricity and the (+) evaporated zinc particles are attracted to the (-) zinc recovery unit. 0.1 KV or more, more preferably 0.5 KV or more.

The electric field is V / m, which is proportional to the magnitude of the voltage to be applied and is inversely proportional to the distance. When the positive field is applied to the evaporation unit, the vaporized zinc gas particle surface is positively charged.

The positively charged evaporative zinc gas particles move downward along the direction of movement of the zinc stream, and when the applied electric field strength, i. As a result, the positive (+) evaporated zinc particles are attracted to the negative (-) zinc recovery part and concentrated in the zinc recovery part.

The zinc-containing substance used in the present invention is not particularly limited, but one or two or more of zinc-containing dust or powder, zinc-containing molded body, galvanized steel sheet scrap, plated steel coil and compressed plated steel sheet scrap are preferable.

As described above, when the zinc is evaporated in the evaporator, the non-oxidizing gas atmosphere is not particularly limited, but it is preferable to use nitrogen gas alone or a mixed gas of nitrogen and hydrogen gas.

When using a mixed gas of nitrogen and hydrogen gas as the non-oxidizing gas atmosphere, the mixing ratio of hydrogen gas is preferably limited to 4% or less.

Since zinc gas heated and evaporated at a high temperature is very active, it reacts even in the presence of a very small amount of oxygen and is produced in the form of zinc oxide. Therefore, it is very important to control the complete non-oxidizing atmosphere in order to recover the metal zinc.

Hydrogen gas is the gas having the best reducing power, and it reacts with oxygen existing in the reactor first and consumes and removes oxygen, thus maintaining a completely non-oxidizing atmosphere, thereby recovering all evaporated zinc in the form of metal zinc.

As described above, when using a mixed gas of nitrogen gas and hydrogen gas, it is preferable to control the hydrogen gas mixing ratio to 4% or less because there is a possibility of explosion when the hydrogen gas mixing ratio exceeds 4%. .

According to the present invention, the reaction vessel may be placed in the evaporation unit according to the form of the zinc inclusion, and the zinc content may be loaded into the reaction vessel to evaporate or the zinc inclusion may be loaded as it is without using the reaction vessel. have.

That is, in the present invention, when the zinc content is in the form of dust or particles, the reaction vessel is placed in an evaporation section, the zinc content is charged into the reaction vessel, and zinc is evaporated, and the zinc content is a zinc-containing molded body. In the case of the form, the zinc-containing molded body may be charged into the reaction vessel or loaded into the evaporation unit without using the reaction vessel and then evaporated.

As the zinc-containing molded body, a zinc-containing dust is molded by an appropriate method.

Briquettes etc. are mentioned.

The material of the reaction vessel is not particularly limited, but heat-resistant steel or graphite is preferable, and a more preferable material is graphite.

When using ordinary steel as a reaction vessel, the service life is shortened due to repeated heat history and high temperature. When using heat resistant steel as a reaction vessel, the heat history and high temperature are less affected. The zinc may react with the container to form an alloy.

In the case of using graphite as a reaction container, since graphite is an inorganic material, since it does not deteriorate even after repeated use at high temperature and does not react with evaporated metal zinc, the material of the reaction container is more preferable.

Hereinafter, the present invention will be described in detail through examples.

(Example)

After cutting the 0.5mm thick galvanized steel sheet with a cutter to prepare a size of about 3cm x 3cm, as shown in Table 1, 2Kg was charged into a cylindrical reaction vessel made of a 10mm thick heat-resistant steel or graphite material, and the reaction vessel lid was sealed. Next, it was placed in the evaporation part of the reaction vessel.

The reaction vessel was used as a vessel having a lower hole (Φ 50mm size).

Directly below the evaporator, a flat plate having a diameter of about 10 cm, which can recover the evaporated zinc, was placed on the zinc recovery section, and the cooling water was circulated to cool the zinc recovery plate.

Before raising the temperature, nitrogen gas or a mixture of 3.5% hydrogen and 96.5% nitrogen was flowed at a flow rate of 2 L / min, and sufficiently purged with nitrogen gas or a mixed gas of 3.5% hydrogen and 96.5% nitrogen to obtain an inert atmosphere. After the conversion, heating was continued while flowing nitrogen gas or a mixed gas of 3.5% hydrogen and 96.5% nitrogen from the elevated temperature to the completion of the reaction.

At this time, as shown in Table 1, the electric field is not applied to the heating and evaporation part (Comparative Example 2), or the negative electric field is connected to the heating and evaporation part (+) field and the zinc recovery part side. While applying (Inventive Examples 1, 2 and 3) or by connecting a (-) electric field to the heating and evaporation part and a positive electric field to the zinc recovery part and applying about 4.0 KV intensity (Comparative Example 2) The reaction was terminated by raising the temperature to 1050 ° C. with a maximum output of 7KW and maintaining it for 40 minutes.

In the case of Inventive Example 1 and Comparative Examples 1 and 2, the weight of the zinc sample recovered from each part of the reactor was measured, including the metal zinc sample recovered from the zinc recovery part after the reaction, and the electric field was recovered from the zinc recovered from the zinc recovery part. The effects were judged and the results are shown in Table 2 below.

Component analysis of the recovered zinc and residual tin was carried out by EDX.

Specimen No. Reaction vessel
material Non-oxidizing gas Electric field condition Input scrap amount
(g) Electric field direction Inventory 1 Heat resistant steel Nitrogen gas 4.0KV Evaporator (+), Recovery (-) 2000 Inventory 2 Graphite Nitrogen gas 4.0KV Evaporator (+), Recovery (-) 2000 Inventory 3 Graphite 3.5% hydrogen + 96.5% nitrogen 4.0KV Evaporator (+), Recovery (-) 2000 Comparative Example 1 Heat resistant steel Nitrogen gas 4.0KV Evaporator (-), Recovery (+) 2005.5 Comparative Example 2 Heat resistant steel Nitrogen gas Vision system - 2000.15

Specimen No. Remaining after reaction
Scrap amount (g) evaporation
Amount of zinc
(g) Zinc Recovery (g) Zinc recovery part Bottom support fixture Bottom of container Total recovery Inventive Example 1 1921 78.99 62.48 (79.1%) 6.71 (8.5%) 0.9 (1.1%) 2.1 (2.8%) 72.3 (91.49%) Inventive Example 2 - 79.80 63.48 (80.8%) - - - 77.12 (96.64%) Inventive Example 3 - 80.2 66.20 (82.5%) - - - 78.2 (97.5%) Comparative Example 1 1920.3 85.2 52.4 (61%) 12.3 (14.4%) 2.6 (2.4%) 7.1 (8.4%) 73.2 (86%) Comparative Example 2 1915.59 84.56 55.8 (65%) 9.4 (11.1%) 5.3 (6.3%) 5.3 (6.3%) 72.2985.4%)

As shown in Table 1 above, the positive field is applied to the evaporation unit for heating or evaporating the substance containing zinc, that is, the zinc recovery unit for recovering evaporated zinc. In the case of applying an electric field (Invention Example 1), the total metal zinc recovery was 91.49%, and the zinc recovery at the zinc recovery side was about 79%.

When the total metal zinc recovery rate of the invention example (1) and the zinc recovery rate on the zinc recovery part side were applied with the electric field application direction opposite to the invention example (1) (comparative example 1), and the electric field was not applied (comparative example 2) Compared with the total metal zinc recovery rate and the zinc recovery rate at the zinc recovery part, respectively, the case of the invention example (1) is about 6% and the zinc recovery part side is higher than the comparative examples (1) and (2). Zinc recovery can be seen that about 15 to 20% improved.

In addition, as a result of analyzing the recovered zinc metal and residual tin iron by EDX, the recovered zinc was confirmed to be pure zinc metal, and the iron was also confirmed to be pure Fe.

As such, it can be seen that the electric field application direction plays a very important role in applying the electric field.

On the other hand, when a graphite material is used as the reaction vessel material, nitrogen gas is used alone as a non-oxidizing gas (Invention Example 2), and when a nitrogen and hydrogen mixed gas containing 3.5% hydrogen gas is used (Invention Example 3). It can be seen that the recovery of zinc recovered on the zinc recovery side is 80.8% and 82.5%, respectively, and the total recovery is 96.64% and 97.5%, respectively.

Inventive Examples 2 and 3 show a slightly higher recovery rate in the zinc recovery unit than inventive example (1) using a heat-resistant steel as the reaction vessel material and nitrogen gas alone, and the total amount of zinc recovery is 5- 6% increase.

This is judged to be the result of using graphite which does not react with metal zinc, compared to Inventive Example (1), in which a part of evaporated zinc reacted with the surface of the reaction vessel to cause alloying when the heat-resistant steel was used as the reaction vessel material.

In the invention example (3) using the mixed gas to which hydrogen gas was added, the galvanized steel sheet, which is a raw material partially surface oxidized, was reduced by hydrogen gas, which is a strong reducing agent, and then heated and evaporated to contribute to the recovery. Compared with (1) and the invention example (3), it is judged that it showed a higher value in the collection total amount.

In summary, the zinc zinc is electrically neutral, but when an electric field is applied, the evaporated zinc particle surface tends to have a positive charge rather than a negative charge, and is more attracted to the zinc recovery portion that is charged with a negative charge. The recovery rate collected on the side seems to have improved.

Therefore, by the evaporation method, a positive electric field is applied to the evaporation part during zinc recovery from the by-product containing zinc to charge the evaporated zinc gas particles with (+), and a negative electric field is applied to the zinc recovery part to give (- It can be clearly confirmed that the electrical recovery system can significantly improve the zinc recovery rate on the zinc recovery side.

1 is a schematic view showing an example of a zinc recovery apparatus according to the present invention

                Explanation of symbols on the main parts of the drawings

One . . . Zinc content 3. . . Condensed metal zinc

10. . . Zinc recovery device 11. . . Evaporator

12. . . Zinc recovery section 14. . . Electric field application device

111. . . Reaction vessel 112. . . Heating source

113. . . Non-oxidizing gas supply pipe

Claims (9)

A method for recovering metal zinc by heating and evaporating a zinc content, Heating the zinc content to evaporate zinc, and a zinc recovery part for recovering the evaporated zinc, comprising: communicating with each other so that the vaporized zinc can communicate with each other and forming a closed system; Evaporating zinc by heating the zinc content in a non-oxidizing gas atmosphere in the evaporator; And Recovering zinc evaporated as described above in the zinc recovery unit; The temperature of the zinc recovery portion is lower than the temperature of the evaporation portion, and during the evaporation and recovery of zinc, the zinc-containing material, characterized in that to apply a (+) electric field to the evaporation part and a (-) electric field to the zinc recovery part Recovery of metal zinc from furnaces. 2. The method of recovering metal zinc from a zinc-containing material according to claim 1, wherein the evaporation section and the zinc recovery section are disposed up and down. The method of recovering metal zinc from a zinc-containing material according to claim 1, wherein the temperature of the zinc recovery part is controlled to be 50 ° C or lower than the temperature of the evaporation part. The zinc-containing material according to claim 1, wherein the zinc-containing material is one or two or more of zinc-containing dust or powder, zinc-containing molded body, zinc-plated steel sheet scrap, plated steel coil and compressed plated steel scrap. Metal zinc recovery method. The method of claim 1, wherein the non-oxidizing gas atmosphere is nitrogen gas alone or a mixed gas of nitrogen and hydrogen gas. The method for recovering metal zinc from zinc-containing materials according to claim 1, wherein a mixed gas of nitrogen and hydrogen gas mixed with hydrogen gas of 4% or less is used as the non-oxidizing gas atmosphere. The method according to claim 1, wherein when the zinc content is in the form of dust or particles, the reaction vessel is placed in an evaporation section, charged with the zinc content in the reaction vessel, and the zinc is evaporated. In the case of a shaped article, the zinc-containing material is charged into the reaction vessel or loaded into the evaporation unit without using the reaction vessel, and then evaporated. 8. The method of claim 7, wherein the reaction vessel is made of a heat-resistant steel or graphite. 9. The method of claim 1, wherein the strength of the electric field is 0.5 KV or more.

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