JP2022089546A - Method for producing zinc carbonate - Google Patents

Abstract

To provide a method for producing a zinc carbonate which selectively extracts a zinc component in a zinc-containing aqueous solution produced using secondary dust generated in electric furnace dust or when the electric furnace dust is reduced in a reduction furnace as a raw material with an alkali hydroxide aqueous solution as an extraction solvent, converts the extracted zinc component into a zinc-containing compound in the form of a carbonate, thereby when producing the zinc carbonate, can convert the by-produced alkali carbonate component or alkali hydrogen carbonate component into an alkali component capable of extracting a zinc component in the zinc-containing aqueous solution.SOLUTION: A method for producing a zinc carbonate includes an alkali regeneration step of using an alkali hydroxide aqueous solution as an extraction solvent for selectively extracting a zinc component in a zinc-containing aqueous solution production step, converting the by-produced alkali component produced in a zinc carbonate separation step into an alkali hydroxide component using an alkali hydroxide aqueous solution, and feeding the alkali hydroxide component into the alkali hydroxide aqueous solution in the zinc-containing aqueous solution production step.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing zinc carbonate, and in particular, in addition to the blast furnace dust generated during melting and smelting of scrap in the blast furnace method, which is one of the iron making processes, a part of the blast furnace dust is reduced when recycled as a zinc raw material. Secondary dust (crude zinc oxide) that recovers secondary dust (crude zinc oxide) generated in the furnace and blast furnace dust generated in the blast furnace method, which is one of the iron-making processes, as zinc-containing oxides in a rotary hearth furnace. The present invention relates to a method for producing zinc carbonate using such so-called secondary dust as a raw material.

In the electric furnace method, which is one of the steelmaking processes, electric furnace dust, which corresponds to about 1.5% to 2.0% of the amount of steelmaking and contains zinc oxide components, is generated during melting and smelting of scrap. It is said that 8 million tons of electric furnace dust is generated in the world and 400,000 tons in Japan.

Most of the iron scrap is abandoned buildings, abandoned home appliances or abandoned automobiles. Zinc plating is applied to the paint base of abandoned buildings, abandoned home appliances, or abandoned automobiles. In addition, the scrap contains paint, plastic, oil and the like. Therefore, in addition to heavy metals such as zinc and lead, the electric furnace dust also contains harmful organic substances such as chlorides and dioxins. On the other hand, the electric furnace dust contains about 20 to 30% iron and 20 to 30% zinc. In addition, crude zinc oxide contains about 10% iron and about 60% zinc. Therefore, electric furnace dust and secondary dust (crude zinc oxide) are very useful as resources.

Under such circumstances, Patent Document 1 relates to a method for producing zinc base metal, and produces a zinc-containing aqueous solution containing a zinc component using electric furnace dust or secondary dust generated when the electric furnace dust is reduced in a reduction furnace as a raw material. The zinc component in the zinc-containing aqueous solution is made into a zinc-containing compound in at least one form of a carbonate, a hydroxide and an oxide, and the zinc component of the zinc-containing compound is chloride to obtain purified zinc chloride. A step of producing purified zinc chloride to be contained, a step of producing anhydrous melt-purified zinc containing anhydrousated melt-purified zinc by anhydrousizing the purified zinc, and an electric solution of anhydrous melt-purified zinc. It discloses a configuration including a step of producing zinc base metal as an electrolytic product by decomposition.

Japanese Unexamined Patent Publication No. 2019-11989

However, according to the study of the present inventor, in the configuration disclosed in Patent Document 1, the filtrate after separating the zinc-containing compound in at least one form of carbonate, hydroxide and oxide is used as electric furnace dust or electric furnace dust. It is repeatedly used as an alkaline agent for selectively extracting the zinc component from the secondary dust, but this is a more appropriate form because it only circulates the alkaline component remaining in the filtrate. There is room for improvement in efficiently sending the alkaline component of the above to the zinc extraction process.

In particular, according to the study of the present inventor, when the electric furnace dust or the secondary dust generated when the electric furnace dust is reduced in the reduction furnace is used as a raw material, the zinc component in the raw material is used as an extraction solvent using an alkaline hydroxide aqueous solution. When zinc carbonate is produced by selectively extracting and using the extracted zinc component as a zinc-containing compound in the form of a carbonate, an alkali carbonate component or an alkali hydrogen carbonate component may be produced as a by-product. If the by-product can be converted into an alkaline component capable of extracting the zinc component in the zinc-containing aqueous solution, a more appropriate form of the alkaline agent can be efficiently used.

The present invention has been made through the above studies, and the zinc component in the zinc-containing aqueous solution generated from the electric furnace dust or the secondary dust generated when the electric furnace dust is reduced in the reduction furnace is used as an alkaline hydroxide aqueous solution. Is selectively extracted as an extraction solvent, and the extracted zinc component is used as a zinc-containing compound in the form of a carbonate to produce zinc carbonate. It is an object of the present invention to provide a method for producing zinc carbonate capable of converting a zinc component in a zinc-containing aqueous solution into an alkaline component capable of extracting the zinc component.

In order to achieve the above object, the method for producing zinc carbonate in the first aspect of the present invention uses electric furnace dust or secondary dust generated when the electric furnace dust is reduced in a reduction furnace as a raw material in the raw material. A zinc-containing aqueous solution generation step of selectively extracting a zinc component to generate a zinc-containing aqueous solution containing the zinc component, and separating the zinc component in the zinc-containing aqueous solution as zinc carbonate to produce the zinc carbonate. A method for producing zinc carbonate, which comprises a zinc carbonate separation step, wherein an alkaline hydroxide aqueous solution is used as an extraction solvent for selectively extracting the zinc component in the zinc-containing aqueous solution generation step, and the zinc carbonate separation is performed. Further provided is an alkali regeneration step of converting the by-product alkaline component produced in the step into an alkali hydroxide component and sending the alkali hydroxide component into the alkali hydroxide aqueous solution in the zinc-containing aqueous solution producing step.

Further, in the present invention, in addition to the first aspect, in the zinc carbonate separation step, the zinc carbonate is separated by bringing carbon dioxide into contact with the zinc-containing aqueous solution, and alkali carbonate is used as the by-product alkali component. The alkali hydroxide component is produced by producing a component or an alkali hydrogen carbonate component, and the alkali carbonate component or the alkali hydrogen carbonate component produced as a by-product in the zinc carbonate separation step is brought into contact with calcium hydroxide in the alkali regeneration step to bring the alkali hydroxide component into contact with the alkali carbonate component. Is the second phase.

Further, in the present invention, in addition to the first or second aspect, the calcium hydroxide to be brought into contact with the alkali carbonate component or the hydrogen carbonate alkali component in the alkali regeneration step is obtained in the zinc-containing aqueous solution generation step. The third aspect is that it is obtained by using the calcium component in the obtained residue.

Further, in the present invention, in addition to any of the first to third aspects, metallic zinc is brought into contact with the zinc-containing aqueous solution produced in the zinc-containing aqueous solution generation step to bring zinc into the zinc-containing aqueous solution. A fourth step is to further include a substitution step of reducing and precipitating a more noble metal impurity component, and the zinc carbonate separation step separates the zinc component in the zinc-containing aqueous solution that has undergone the substitution step as the zinc carbonate. It is the phase of.

Further, in the present invention, in addition to any of the first to third aspects, the zinc-containing aqueous solution produced in the zinc-containing aqueous solution generation step is brought into contact with an oxidizing agent to bring iron into the zinc-containing aqueous solution. Metallic zinc is brought into contact with the zinc-containing aqueous solution that has undergone the deironing and demangaling step of separating the components and the manganese component, and the metal impurity component that is more noble than zinc in the zinc-containing aqueous solution is reduced. The zinc carbonate separation step further comprises a precipitation replacement step, and the fifth aspect of the zinc carbonate separation step is to separate the zinc component in the zinc-containing aqueous solution that has undergone the replacement step as the zinc carbonate.

According to the method for producing zinc carbonate in the first aspect of the present invention, an alkaline hydroxide aqueous solution was used as an extraction solvent for selectively extracting the zinc component in the zinc-containing aqueous solution generation step, and the zinc carbonate was produced in the zinc carbonate separation step. Since the by-product alkaline component is further provided with an alkali regeneration step of converting the by-product alkaline component into an alkali hydroxide component and sending the alkaline hydroxide component into the alkaline hydroxide aqueous solution in the zinc-containing aqueous solution generation step, the by-produced alkaline component is used. The zinc component in the zinc-containing aqueous solution can be converted into an alkaline component capable of extracting the zinc component, and zinc carbonate can be produced more efficiently by efficiently using an alkaline agent having a more appropriate form.

Further, according to the method for producing zinc carbonate in the second aspect of the present invention, zinc carbonate is separated by contacting carbon dioxide with a zinc-containing aqueous solution in the zinc carbonate separation step, and alkali carbonate is used as a by-product alkaline component. A component or an alkali hydrogen carbonate component is generated, and an alkali hydroxide component is produced by contacting the alkali carbonate component or the alkali hydrogen carbonate component produced as a by-product in the zinc carbonate separation step with calcium hydroxide in the alkali regeneration step. Therefore, it is possible to convert the by-produced alkaline components such as sodium carbonate and sodium hydrogen carbonate into alkaline components such as sodium hydroxide and reuse them as an extraction solvent capable of extracting the zinc components in the zinc-containing aqueous solution. , Zinc carbonate can be produced more efficiently by circulating and using the extraction solvent without discarding it.

Further, according to the method for producing zinc carbonate in the third aspect of the present invention, calcium hydroxide that comes into contact with the alkali carbonate component or the alkali hydrogen carbonate component in the alkali regeneration step is contained in the residue obtained in the zinc-containing aqueous solution generation step. Since it was obtained by using the calcium component of the above, the calcium component in the raw material of the zinc-containing aqueous solution can be effectively used, and zinc carbonate can be produced more efficiently.

Further, according to the method for producing zinc carbonate in the fourth aspect of the present invention, metallic zinc is brought into contact with the zinc-containing aqueous solution produced in the zinc-containing aqueous solution generation step, and the metal is noble than zinc in the zinc-containing aqueous solution. Since the zinc carbonate separation step further separates the zinc component in the zinc-containing aqueous solution that has undergone the substitution step as zinc carbonate, the zinc carbonate has a reduced metal impurity component. Can be mass-produced with good yield and stability.

Further, according to the method for producing zinc carbonate in the fifth aspect of the present invention, an oxidizing agent is brought into contact with the zinc-containing aqueous solution produced in the zinc-containing aqueous solution generation step to remove the iron component and the manganese component in the zinc-containing aqueous solution. Further, a deironing demanganese step for separation and a replacement step in which metallic zinc is brought into contact with the zinc-containing aqueous solution that has undergone the deironing and demangaling step to reduce and precipitate a metal impurity component nobler than zinc in the zinc-containing aqueous solution. Since the zinc carbonate separation step separates the zinc component in the zinc-containing aqueous solution that has undergone the replacement step as zinc carbonate, zinc carbonate with reduced iron and manganese components is mass-produced with good yield and stability. be able to.

FIG. 1 (a) is a process diagram of the method for producing zinc carbonate in the first embodiment of the present invention, and FIG. 1 (b) is a secondary diagram which can be used as a raw material for the method for producing zinc carbonate in the present embodiment. It is a process diagram which generates dust. FIG. 2 is a process diagram of a method for producing zinc carbonate according to the second embodiment of the present invention. FIG. 3 is a process diagram of a method for producing zinc carbonate according to the third embodiment of the present invention. FIG. 4 is Table 1 showing the results of an experimental example of the first embodiment of the present invention. FIG. 5 is Table 2 showing the results of an experimental example of the second embodiment of the present invention. FIG. 6 is Table 3 showing the results of an experimental example of the third embodiment of the present invention.

Hereinafter, the method for producing zinc carbonate according to each embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

(First Embodiment)
First, with reference to FIG. 1, the method for producing zinc carbonate according to the first embodiment of the present invention will be described in detail.

FIG. 1 (a) is a diagram showing a process of the method for producing zinc carbonate in the present embodiment, and FIG. 1 (b) is a diagram for producing secondary dust that can be used as a raw material for the method for producing zinc carbonate in the present embodiment. It is a process diagram to be performed.

As shown in FIG. 1A, in the present embodiment, the zinc extraction step 101 and the zinc carbonate separation step 102 are sequentially executed, and the alkali regeneration step 103 is executed. The zinc extraction step 101 corresponds to the zinc-containing aqueous solution generation step. A manufacturing concept that gives priority to producing an aqueous solution obtained by extracting a zinc component from electric furnace dust or secondary dust as a raw material, and produces zinc carbonate as a zinc-containing compound in the form of a carbonate produced from the zinc component in the aqueous solution. Is based on.

Specifically, first, in the zinc extraction step 101, an aqueous solution of an electric furnace dust 1 as a raw material containing a zinc-containing compound such as zinc oxide and an iron compound such as iron oxide and an alkaline agent 3 as a zinc extraction solvent. As a zinc extract that selectively extracts the zinc component from the zinc-containing compound, a zinc-containing alkaline agent aqueous solution 5 containing the zinc component is produced, and a solid that is insoluble in the aqueous solution of the alkaline agent 3 is produced. The minute was the residue 4.

Typically, a chemical formula for obtaining a zinc-containing alkaline agent aqueous solution 5 which is a zinc-containing aqueous solution in which a zinc component is selectively extracted by using sodium hydroxide as an alkaline agent 3 with respect to zinc oxide in the electric furnace dust 1. Is shown in (Chemical formula 1) below.

As the raw material used in the zinc extraction step 101, secondary dust 2 obtained by reducing the electric furnace dust 1 in a reduction furnace may be used instead of the electric furnace dust 1. Further, as the raw material used in the zinc extraction step 101, when the calcination step 104 shown in FIG. 1 (b) is adopted, that step is used.
Secondary dust 2 obtained by mixing calcium carbonate 10 with electric furnace dust 1 and baking it may be used.
By such calcination, the zinc component contained in the zinc ferrite component of the electric furnace dust 1 can be converted into a zinc oxide component that can be easily extracted with an alkaline agent. When the secondary dust 2 obtained by mixing or baking calcium carbonate 10 is used as a raw material in this way, the calcium component in the residue 4 obtained in the zinc extraction step 101 can be increased. Further, the carbon dioxide 6 obtained by such calcination can be used in the next zinc carbonate separation step 102. Further, as the raw material used in the zinc extraction step 101, secondary dust such as crude zinc hydroxide obtained from the electric furnace dust 1 may be used.

Next, in the zinc carbonate separation step 102, the zinc-containing alkaline agent aqueous solution 5 containing the zinc component extracted in the zinc extraction step 101 and the carbon dioxide (carbon dioxide gas) 6 are brought into direct contact with each other in the zinc extraction step 101. Zinc carbonate 7 was precipitated from the extracted zinc-containing alkaline agent aqueous solution 5 containing the zinc component, and the zinc carbonate 7 was separated into solid and liquid and recovered as a solid, which was used as it was as a product.

Typically, as shown in the following chemical formula (Chemical formula 2), carbon dioxide 6 is blown into the zinc component in the zinc-containing alkaline agent aqueous solution 5 represented by the chemical formula (Chemical formula 1) to precipitate zinc carbonate 7. By filtering the precipitated zinc carbonate 7 as described above, zinc carbonate 7 as a solid content can be obtained.

In the zinc carbonate separation step 102, a liquid containing carbonate ions may be used instead of the carbon dioxide 6 that is brought into contact with the zinc-containing alkaline agent aqueous solution 5. Further, as is clear from the chemical formula (Chemical Formula 2), excess hydroxide ion is required for zinc hydroxide to dissolve in the alkaline aqueous solution. Therefore, in the zinc carbonate separation step 102, instead of zinc carbonate 7 or zinc carbonate. At the same time, zinc hydroxide can be precipitated. Since zinc carbonate and zinc hydroxide have the property of becoming zinc oxide when heated, a part of zinc carbonate may be zinc oxide as well as zinc hydroxide. In addition, by repeating the precipitation and redissolution of zinc carbonate and zinc hydroxide by methods such as heating, cooling, and pH adjustment of the zinc-containing alkaline agent aqueous solution 5 containing a zinc component, the purification effect is further actively utilized. High-purity products can also be obtained.

Here, in the alkali regeneration step 103, the alkali carbonate component and the alkali hydrogen carbonate component are contained as a by-product in the filtrate 8 after the solid-liquid separation of zinc carbonate 7 in the zinc carbonate separation step 102. The alkaline carbonate component and the alkaline hydrogen carbonate component are converted into the alkaline hydroxide component, and the alkaline agent 3 composed of the thus converted alkaline hydroxide component is returned to the aqueous solution of the alkaline agent 3 in the zinc extraction step 101.

Typically, calcium hydroxide 9 is added to the filtrate 8 after the solid-liquid separation of zinc carbonate 7 in the zinc carbonate separation step 102 to convert sodium carbonate or sodium hydrogen carbonate to sodium hydroxide. The sodium hydroxide thus converted is used as the alkaline agent 3 and returned to the aqueous solution of the alkaline agent 3 in the zinc extraction step 101. The chemical formula for obtaining sodium hydroxide from sodium carbonate and calcium hydroxide is shown in (Chemical Formula 3) below.

In the alkali regeneration step 103, when the zinc-containing alkaline agent aqueous solution 5 is produced in the zinc extraction step 101 as the calcium hydroxide 9 to be added to the filtrate 8 after the solid-liquid separation of zinc carbonate 7 in the zinc carbonate separation step 102. Calcium hydroxide 9 containing a calcium component contained in the obtained residue 4 may be used. As the calcium component in the residue 4, if the calcium component is contained in the electric furnace dust 1 or the secondary dust 2, it can be used, or the calcium carbonate 10 is mixed with the electric furnace dust 1. When baking or adopting the baking step 104, the calcium component derived from the calcium carbonate 10 can also be used. Further, as the calcium hydroxide 9, not only those derived from such a calcium component but also commercially available slaked lime may be used.

In the above method for producing zinc carbonate in the present embodiment, an alkaline hydroxide aqueous solution is used as an extraction solvent for selectively extracting the zinc component in the zinc-containing aqueous solution generation step 101, and the sub-zinc produced in the zinc carbonate separation step 102 is used. Since it further comprises an alkali regeneration step 103 in which the raw alkali component is converted into an alkali hydroxide component and the alkali hydroxide component is sent into the alkali hydroxide aqueous solution in the zinc-containing aqueous solution generation step, the by-produced alkaline component is used. The zinc component in the zinc-containing aqueous solution can be converted into an alkaline component capable of extracting the zinc component, and zinc carbonate can be produced more efficiently by efficiently using an alkaline agent having a more appropriate form.

Further, in the method for producing zinc carbonate of the present embodiment, in the zinc carbonate separation step 102, zinc carbonate is separated by contacting carbon dioxide with a zinc-containing aqueous solution, and an alkali carbonate component or hydrogen carbonate is used as a by-product alkaline component. This is because the alkaline component is generated and the alkali hydroxide component is generated by contacting the alkali carbonate component or the alkali hydrogen carbonate component produced as a by-product in the zinc carbonate separation step 102 with calcium hydroxide in the alkali regeneration step 103. , By-produced alkaline components such as sodium carbonate and sodium hydrogen carbonate can be converted into alkaline components such as sodium hydroxide and reused as an extraction solvent capable of extracting the zinc component in the zinc-containing aqueous solution. Zinc carbonate can be produced more efficiently by recycling without discarding the solvent.

Further, in the method for producing zinc carbonate of the present embodiment, the calcium hydroxide brought into contact with the alkali carbonate component or the alkali hydrogen carbonate component in the alkali regeneration step 103 uses the calcium component in the residue obtained in the zinc-containing aqueous solution generation step. Since it is obtained by using it, calcium in the raw material of the zinc-containing aqueous solution can be effectively used, and zinc carbonate can be produced more efficiently.

(Second embodiment)
Next, with reference to FIG. 2, the method for producing zinc carbonate according to the second embodiment of the present invention will be described in detail.

FIG. 2 is a diagram showing a process of a method for producing zinc carbonate in the present embodiment.

As shown in FIG. 2, the method for producing zinc carbonate according to the present embodiment is between the zinc extraction step 101 and the zinc carbonate separation step 102, as compared with the method for producing zinc carbonate according to the first embodiment. The main difference is that it has a replacement step (sementation step) 105. In the present embodiment, the description will be focused on such differences, and the same components will be designated by the same reference numerals, and the description thereof will be omitted or simplified.

Specifically, in the replacement step 105 following the zinc extraction step 101, a zinc-containing alkaline agent aqueous solution 5 as a zinc extract containing the zinc component extracted in the zinc extraction step 101, metallic zinc 11 such as zinc fine particles, and the like, To reduce and precipitate metal impurity components 12 such as copper, lead, and cadmium, which are more noble than zinc in the zinc-containing alkaline agent aqueous solution 5, to reduce the concentration of the impurity components in the zinc-containing alkaline agent aqueous solution 5. is doing.

Next, in the zinc carbonate separation step 102, the zinc-containing alkaline agent aqueous solution 13 in which the concentration of the impurity component was reduced in the replacement step 105 and the carbon dioxide 6 are brought into contact with each other, and the zinc-containing alkaline agent aqueous solution 13 to the zinc carbonate 7 are brought into contact with each other. Is deposited, and it is separated into solid and liquid and recovered as a solid substance.

According to the above-mentioned method for producing zinc carbonate of the present embodiment, in addition to the configuration of the first embodiment, metallic zinc is brought into contact with the zinc-containing aqueous solution produced in the zinc-containing aqueous solution generation step 101 to bring the zinc-containing aqueous solution into contact with the zinc-containing aqueous solution. Since it further has a substitution step 105 for reducing and precipitating a metal impurity component that is more noble than zinc in the zinc, zinc carbonate having a reduced metal impurity component can be mass-produced in a stable manner with a good yield.

(Third embodiment)
Next, with reference to FIG. 3, the method for producing zinc carbonate according to the third embodiment of the present invention will be described in detail.

FIG. 3 is a diagram showing a process of a method for producing zinc carbonate in the present embodiment.

As shown in FIG. 3, the method for producing zinc carbonate according to the present embodiment is compared with the method for producing zinc carbonate according to the second embodiment, and is removed between the zinc extraction step 101 and the substitution step 105. The main difference is that it has an iron demanganese step 106. In the present embodiment, the description will be focused on such differences, and the same components will be designated by the same reference numerals, and the description thereof will be omitted or simplified.

In the present embodiment, the provision of the iron removal and manganese removal step 106 is particularly necessary when the iron component or manganese component contained in the electric furnace dust or the like is Fe (II), Mn (II) or the like soluble in alkali. It is effective, and even when the iron component or manganese component is insoluble in alkali, for example, a zinc-containing aqueous solution in which Fe (III) and Mn (IV) insoluble in alkali are suspended is replaced. Treatment in the step is effective because they are reduced to Fe (II) or the like soluble in alkali and dissolved in the iron-containing aqueous solution. Further, since an iron component or a manganese component soluble in alkali may be generated in the replacement step 105, not only the replacement step is provided after the iron removal and demanganese removal step, but also the replacement step is performed before the iron removal and demanganese removal step. It may be provided. Specific methods of the deironing and demanganese step 106 include an oxidation method by aeration and addition of permanganate, and when the soluble manganese component is Mn (VII), the active carbon is used. The method of contacting is mentioned.

Specifically, in the deironing demanganese step 106 following the zinc extraction step 101, the iron component and the solubility contained in the zinc-containing alkaline agent aqueous solution 5 as the zinc extract containing the zinc component extracted in the zinc extraction step 101. In order to remove manganese, the iron or soluble manganese component contained in the zinc-containing alkaline agent aqueous solution 5 is oxidized, and the iron component and manganese component in the zinc-containing alkaline agent aqueous solution 5 are insoluble precipitates. Separated and removed as sludge 17. Specifically, a gas containing oxygen is blown into the zinc-containing alkaline agent aqueous solution 5 (for example, air blown, that is, aeration), and an oxidizing agent 15 such as permanganate, chlorate, and chlorine dioxide is added. Then, the 1st iron component in the zinc-containing alkaline agent aqueous solution 5 is oxidized to the 2nd iron component, and the soluble manganese is oxidized to be converted into an insoluble manganese compound and separated and removed as sludge 17. Further, the iron component in the zinc-containing alkaline agent aqueous solution 5 controls the temperature, the alkali concentration and the redox potential (ORP) value to form magnetic iron oxide such as maghemite containing both the ferrous component and the ferric component. You can also do it.

When permanganate is used as the oxidizing agent 15, the permanganate can be supplied until the excess permanganate remains in the zinc-containing alkaline agent aqueous solution 5 to determine the end point of demanganese. The remaining permanganate is removed by bringing it into direct contact with activated carbon to convert it into insoluble manganese dioxide.

Next, in the replacement step 105, the zinc-containing alkaline agent aqueous solution 16 in which the concentration of the impurity component was reduced in the iron removal and manganese removal step 106 and the metallic zinc 11 such as zinc fine particles are brought into contact with each other to bring the zinc-containing alkaline agent aqueous solution into contact with each other. The metal impurity component 12 such as copper, lead, and cadmium, which is more noble than zinc in 16, is reduced and precipitated to further reduce the concentration of the impurity component in the zinc-containing alkaline agent aqueous solution 16.

Here, regarding the order of implementation of the deironing demanganese step 106 and the replacement step 105, the subsequent step of the replacement step 105 may be the deironing demanganese step 106. For example, when the raw material has undergone an iron reduction step such as secondary dust, there are cases where the iron component contained in the raw material contains a large amount of divalent (Fe (II): ferrous iron component). This is because it is more rational to carry out the replacement step 105 first when processing the raw material. Further, such a situation is the same in the embodiment in which the deironing demanganese step 106 is separated into the deironing step and the demanganese step and each is individually executed.

According to the above-mentioned method for producing zinc carbonate according to the present embodiment, in addition to the configuration of the second embodiment, the zinc-containing aqueous solution produced in the zinc-containing aqueous solution generation step 101 is brought into contact with an oxidizing agent to bring the zinc-containing aqueous solution into contact with the zinc-containing aqueous solution. Since it further has a deironing demanganese step 106 for separating the iron component and the manganese component in the zinc carbonate, zinc carbonate having a reduced iron component and manganese component can be mass-produced in a stable manner with a good yield.

Finally, with respect to the present embodiment described above, experimental examples corresponding to the first to third embodiments will be described in detail with reference to FIGS. 4 to 6.

FIG. 4 is Table 1 corresponding to the results of Experimental Example 1 of the first embodiment of the present invention, and FIG. 5 is Table 2 showing the results of Experimental Example 2 of the second embodiment of the present invention. FIG. 6 is a table 3 showing the results of Experimental Example 2 according to the third embodiment of the present invention. In addition, ND in the table indicates that it was not detected. In addition, the blanks in the table indicate that the electric furnace dust, secondary dust and residue are below the detection limit or are not detected, and the items other than the electric furnace dust, secondary dust and residue are out of the analysis items. Is shown.

(Experimental Example 1)
This experimental example corresponds to the first embodiment of the present invention, and the results are shown in Table 1 of FIG.

First, in the zinc extraction step 101, 60. From 870 g of secondary dust obtained by mixing and baking 441 g of calcium carbonate and 762.8 g of electric furnace dust 1 in advance in the caustic step 104. Secondary dust 2 having a weight of 5 g is separated, and the separated secondary dust 2 is brought into contact with an aqueous solution of NaOH having a concentration of 16.5% as an aqueous solution of the alkaline agent 3 and dissolved in the aqueous solution of the alkaline agent 3. A zinc extract (zinc-containing alkaline agent aqueous solution) 5 having a volume of 395 ml was obtained as the remaining liquid obtained by separating the non-solid content by filtration. Further, the solid content insoluble in the aqueous solution of the alkaline agent 3 was filtered, washed with pure water, and then dried to obtain a residue 4 having a weight of 43.3 g. Under the extraction conditions in the zinc extraction step 101, the temperature was 95 ° C. and the pressure was normal pressure, and the contact time between the aqueous solution of the alkaline agent 3 and the secondary dust 2 was 8 hours. The filtrate obtained by filtering out the residue 4 (the filtrate obtained by extracting the components that can be extracted from the insoluble solid content) is then repeatedly used as the alkaline agent 3 for dissolving the secondary dust 2, and the residue 4 is pure. The washing water after washing with water was repeatedly used as diluted water in the purification process.

Next, in the zinc carbonate separation step 102, carbon dioxide 6 is blown into the zinc-containing alkaline agent aqueous solution 5 to precipitate zinc carbonate 7, and zinc carbonate 7 is removed by suction and filtration using a GF (glass fiber) / C filter paper. It was separated and this zinc carbonate 7 was used as it was as a product. As the carbon dioxide 6, the carbon dioxide generated by the decomposition of calcium carbonate 10 when the electric furnace dust 1 in the calcination step 104 was calcinated was used. The composition of zinc carbonate 7 and the like is shown in Table 1, and the value of zinc carbonate 7 is an analytical value obtained by converting it into zinc oxide at the time of heating and drying for convenience.

Then, in the alkali regeneration step 103, the caustic 9 is brought into contact with the filtrate 8 after the zinc carbonate 7 is separated, and when the carbon dioxide 6 is blown into the zinc-containing alkaline agent aqueous solution 5 in the zinc carbonate separation step 102, it is secondary. The produced Na ₂ CO ₃ and NaOH ₃ were converted to NaOH, and this NaOH was sent to the zinc extraction step 101 as an alkaline agent 3 and used repeatedly for zinc extraction. The slaked lime 9 is a calcium component derived from calcium carbonate 10 used when calcinating the electric furnace dust 1 in the calcination step 104, and is obtained by using the calcium component contained in the residue 4 of the zinc extraction step 101. Was used.

(Experimental Example 2)
This experimental example corresponds to the second embodiment of the present invention, and the results are shown in Table 2 of FIG.

First, in the zinc extraction step 101, the secondary dust (crude zinc hydroxide sample) 2 having a weight of 100 g derived from the electric furnace dust 1 and the NaOH aqueous solution having a concentration of 16.5% as the aqueous solution of the alkaline agent 3 are brought into contact with each other. After stirring, the whole amount was filtered. Next, the solid content that was not dissolved in the aqueous solution of the alkaline agent 3 and the NaOH aqueous solution having a concentration of 16.5% as a new aqueous solution of the alkaline agent 3 were brought into contact with each other, stirred, and then the whole amount was filtered. The solid content that is not dissolved in the aqueous solution of each of the alkaline agents 3 is separated by filtration to obtain the residue 4, and the remaining liquid from which the residue 4 is separated is used as a zinc extract having a zinc concentration of 45,800 ppm. (Zinc-containing alkaline agent aqueous solution) 5 was obtained. The conditions such as temperature in the zinc extraction step 101 of this experimental example were the same as those of experimental example 1.

Next, in the replacement step 105, 5 g of powdered zinc particles 11 having an average particle diameter of about 6 μm are added to the zinc-containing alkaline agent aqueous solution 5 and then heated and stirred, and the stirred product is filtered with a filtration accuracy of 0.1 μm. The mixture was sucked and filtered with a filter to obtain a zinc-containing alkaline agent aqueous solution 13 as a filtrate. Further, what was separated from the solid content on the membrane filter was a mixture of the metal powder 12 reduced and precipitated by the dissolution of the zinc particles 11 and the powdery zinc remaining undissolved.

Next, the zinc carbonate separation step 102 following the replacement step 105 was carried out using the zinc-containing alkaline agent aqueous solution 13 with the same contents as those of Experimental Example 1, and the separated zinc carbonate 7 was used as it was as a product. The composition of zinc carbonate 7 obtained in this experimental example is as shown in Table 2, and the metal impurity components such as copper, lead, and cadmium were reduced as compared with those in experimental example 1. The value of zinc carbonate 7 is an analytical value obtained by converting it into zinc oxide during heating and drying for convenience.

Then, in the alkali regeneration step 103, when the calcium hydroxide 9 is brought into contact with the filtrate 8 after the zinc carbonate 7 is separated, and the carbon dioxide 6 is blown into the zinc-containing alkaline agent aqueous solution 5 in the zinc carbonate separation step 102. The by-produced Na ₂ CO ₃ and NaOH ₃ were converted to NaOH, and this NaOH was sent to the zinc extraction step 101 as an alkaline agent 3 and used repeatedly for zinc extraction. The calcium hydroxide 9 was a calcium component derived from the secondary dust 2 used in the zinc extraction step 101, and was obtained by using the calcium component contained in the residue 4 of the zinc extraction step 101.

(Experimental Example 3)
This experimental example is an experimental example corresponding to the third embodiment of the present invention, and the results are shown in Table 3 of FIG.

First, in the zinc extraction step 101, the secondary dust (crude zinc hydroxide sample) 2 having a weight of 300 g derived from the electric furnace dust 1 and the NaOH aqueous solution having a concentration of 16.5% as the aqueous solution of the alkaline agent 3 are brought into contact with each other. After stirring, the whole amount was filtered to obtain a zinc extract (zinc-containing alkaline agent aqueous solution) 5 having a volume of 1800 ml as the remaining liquid from which the solid content insoluble in the aqueous solution of the alkaline agent 3 was separated. Next, the solid content that was not dissolved in the aqueous solution of the alkaline agent 3 and the NaOH aqueous solution having a concentration of 16.5% as a new aqueous solution of the alkaline agent 3 were brought into contact with each other, stirred, and then the whole amount was filtered to make the alkali. The solid content insoluble in the aqueous solution of the agent 3 was separated by filtration to obtain a residue 2 having a weight of 161 g. The conditions in the zinc extraction step 101 of this experimental example were the same as those of experimental example 1.

Next, in the iron removal and manganese removal step 106 following the zinc extraction step 101, the brown precipitate deposited by blowing air as the oxidizing agent 11 into the zinc-containing alkaline agent aqueous solution 5 under heating has a filtration accuracy of 0.1 μm. A filtrate (deironated and demangalated zinc-containing alkaline agent aqueous solution 16) was obtained by suctioning and filtering with a membrane filter. As a solid content on the filter paper, 263 mg by weight of deironized demanganese sludge 17 was obtained.

Next, the replacement step 103 following the iron removal and demanganese removal step 106 is carried out using the zinc-containing alkaline agent aqueous solution 16 with the same contents as those of Experimental Example 2, and the zinc carbonate separation step 102 and the alkali regeneration step 103 are performed. The same content as that of Experimental Example 2 was carried out, and the zinc carbonate 7 separated in the zinc carbonate separation step 102 was used as it was as a product. The composition of zinc carbonate 7 obtained in this experimental example is as shown in Table 3, and the metal impurity components such as iron and manganese were reduced as compared with those in experimental example 2. The value of zinc carbonate 7 is an analytical value obtained by converting it into zinc oxide during heating and drying for convenience.

The present invention is not limited to the above-described embodiment in terms of the shape, arrangement, number, etc. of the constituent elements, and deviates from the gist of the invention, such as appropriately substituting such constituent elements with those having the same effect. Of course, it can be changed as appropriate as long as it is not.

As described above, in the present invention, the zinc component in the zinc-containing aqueous solution generated from the electric furnace dust or the secondary dust generated when the electric furnace dust is reduced in the reduction furnace as a raw material is used as an extraction solvent using an alkaline hydroxide aqueous solution. When zinc carbonate is produced by selectively extracting and using the extracted zinc component as a zinc-containing compound in the form of a carbonate, an alkali carbonate component or an alkali hydrogen carbonate component produced as a by-product is contained in a zinc-containing aqueous solution. Since it is possible to provide a method for producing zinc carbonate that can be converted into an alkaline component that can extract the zinc component of zinc, it is one of the widespread iron making processes due to its general-purpose universal nature. According to the method, it can be applied to the method for producing zinc carbonate using the secondary dust generated in the reduction furnace when recycling the electric furnace dust generated during the melting and smelting of scrap or a part of the electric furnace dust as the raw material for iron making. Be expected.

1 ... Electric furnace dust 2 ... Secondary dust 3 ... Alkaline agent 4 ... Residue 5 ... Zinc-containing alkaline agent aqueous solution 6 ... Carbon dioxide 7 ... Zinc carbonate 8 ... Filter 9 ... Calcium hydroxide 10 ... Calcium carbonate 11 ... Zinc particles 12 ... Metal impurity component 13 ... Zinc-containing alkaline agent aqueous solution 15 ... Oxidizing agent 16 ... Zinc-containing alkaline agent aqueous solution 17 ... Sludge 101 ... Zinc-containing aqueous solution generation step 101 ... Zinc extraction step 102 ... Zinc carbonate separation step 103 ... Alkaline regeneration step 104 ...? Baking step 105 ... Replacement step 106 ... Deironing and demangaling step

Claims (5)

Using the electric furnace dust or the secondary dust generated when the electric furnace dust is reduced in the reduction furnace as a raw material, zinc in the raw material is selectively extracted to generate a zinc-containing aqueous solution containing the zinc component. The process of producing the contained aqueous solution and
A zinc carbonate separation step of separating the zinc component in the zinc-containing aqueous solution as zinc carbonate to obtain the zinc carbonate as a product.
It is a manufacturing method of zinc carbonate provided with
An alkaline hydroxide aqueous solution is used as an extraction solvent for selectively extracting the zinc component in the zinc-containing aqueous solution generation step.
Further comprising an alkali regeneration step of converting the by-product alkaline component produced in the zinc carbonate separation step into an alkali hydroxide component and sending the alkali hydroxide component into the alkali hydroxide aqueous solution in the zinc-containing aqueous solution producing step. How to make zinc carbonate. In the zinc carbonate separation step, the zinc carbonate is separated by bringing carbon dioxide into contact with the zinc-containing aqueous solution, and an alkali carbonate component or an alkali hydrogen carbonate component is generated as the by-product alkaline component.
The carbonic acid according to claim 1, wherein the alkali hydroxide component is produced by contacting the alkali carbonate component or the alkali hydrogen carbonate component produced as a by-product in the zinc carbonate separation step with calcium hydroxide in the alkali regeneration step. How to make zinc. The claim that the calcium hydroxide to be brought into contact with the alkali carbonate component or the hydrogen carbonate alkali component in the alkali regeneration step is obtained by using the calcium component in the residue obtained in the zinc-containing aqueous solution generation step. 2. The method for producing zinc carbonate according to 2. Further comprising a substitution step of bringing metallic zinc into contact with the zinc-containing aqueous solution produced in the zinc-containing aqueous solution generation step to reduce and precipitate a metal impurity component nobler than zinc in the zinc-containing aqueous solution.
The method for producing zinc carbonate according to any one of claims 1 to 3, wherein the zinc carbonate separation step separates the zinc component in the zinc-containing aqueous solution that has undergone the replacement step as the zinc carbonate. A deironing and demanganese step of contacting an oxidizing agent with the zinc-containing aqueous solution produced in the zinc-containing aqueous solution generation step to separate iron components and manganese components in the zinc-containing aqueous solution.
A replacement step of bringing metallic zinc into contact with the zinc-containing aqueous solution that has undergone the iron-removing and manganese-removing step to reduce and precipitate a metal impurity component that is nobler than zinc in the zinc-containing aqueous solution.
Further have
The method for producing zinc carbonate according to any one of claims 1 to 3, wherein the zinc carbonate separation step separates the zinc component in the zinc-containing aqueous solution that has undergone the replacement step as the zinc carbonate.

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