KR19990080650A - Recovery method of zinc carbonate and sodium carbonate - Google Patents

Abstract

The present application removes water-soluble components from electric furnace dust, which is a large amount of industrial waste generated in water, and then reacts the remaining iron and zinc components with concentrated sodium hydroxide, and reacts the resulting sodium zincate with carbon dioxide gas. After the complex salt is formed, the separation of high purity zinc carbonate and sodium carbonate is started therefrom.

Since the installation cost for carrying out the present invention is inexpensive, even in small and medium-sized companies, zinc carbonate can be recovered very economically from the electric furnace Dast without significant burden.

In addition, the high purity zinc carbonate thus obtained can be converted into zinc oxide, zinc chloride or the like by a further known method and used as a main raw material for various products.

Description

Process for simultaneous recovering zinc carbonate and sodium carbonate from iron dust

The present invention relates to a method for the simultaneous recovery of zinc carbonate (ZnCO ₃ ) and sodium carbonate in an electric furnace.

Recently, the electric furnace Dast is a company that produces rebar and iron materials using various scrap metals.In particular, in Korea, companies that produce rebars are mainly made from scrap metals such as Incheon Steel, Dongkuk Steel, Kangwon Industrial, Hanbo Steel, etc. As a byproduct, its amount exceeds about 200,000 tons per year, but it cannot be recycled and is entirely buried. Such treatment costs exceed 20 billion won / year, polluting the environment such as soil, which is becoming a serious social problem.

These furnaces are generated by the evaporation of scrap iron, such as scrap cars, in a high-temperature furnace at 1800 ℃. The composition of the furnace varies depending on the type of scrap metal and the processing company. I knew I had

Iron (Fe): 20-30%, Zinc (Zn): 15-30%, Chlorine (Cl): 0.5-2.5%,

Lead (Pb): 1-8%, copper (Cu): 0.2-0.4%, fluorine (F): 0.2-0.4%,

Sodium oxide (Na2O): 2-4%, manganese (Mn): 1.5-2.5%, other impurities 5-10%.

On the other hand, if zinc carbonate and sodium carbonate among the components can be separated with high purity, expensive soft ferrites (main components: MnO, Fe ₂ O ₃ and ZnO, reference: US Patent No. 5,629,100) used in various electronic components or semiconductor components , Copper 5,698,145, copper 5,688,430, 5,200,159 and the like, and additives such as main components of hard ferrite, pesticides, detergents and the like. Particularly, since zinc compounds depend entirely on imports, providing high-purity separation of zinc carbonate and sodium carbonate from zinc and iron containing a large amount of constituents of the furnace is not only an import substitution effect, but also an industrial waste electricity. Recycling the furnace will economically benefit and preserve the environment.

Among the main components of the electric furnace, economical recoverable components are iron and zinc. The iron or zinc is converted to iron chloride (FeCl ₂ , FeCl ₃ ) and zinc chloride (ZnCl ₂ ) when dissolved with hydrochloric acid, and converted to iron sulfate [FeSO ₄ , Fe 2 (SO ₄ ) ₃ ] when dissolved with sulfuric acid. However, it is almost impossible to recover and recover pure zinc oxide and iron oxide from iron and zinc compounds of chlorides and sulfates. Therefore, the method of recovering zinc or iron was not successful. Therefore, in steel mills and the like, the electricity is oxidized and discarded as oxides. Since these wastes are oxides, the leakage of heavy metals can be prevented. However, when the wastes are disposed of in the soil or landfills due to the amount of discharged, the amount of metal oxides is relatively high compared to the soil components, which causes the soil to be desolated. The cost is not small either.

The present inventors earnestly researched to solve the above problems, and in order to separate and recover zinc and iron, which are the main components in the electric furnace, iron and zinc in the electric furnace are dissolved with nitric acid and iron nitrate [Fe ( NO ₃ ) ₂ , Fe (NO ₃ ) ₃ ] and zinc nitrate [Zn (NO ₃ ) ₂ ], and these nitrates are reduced at low temperature using organic hydrocarbon as a reducing agent to recover pure iron oxide and zinc oxide. The patent application regarding the method was filed (patent application No. 98-12296). However, this method is very satisfactory in the recovery rate of iron oxide and zinc oxide or their purity, but the oxidation and acid resistance of the inner wall of the gas delivery pipe to recycle and recycle the nitrogen oxide gas discharged during the large-scale facility, i.e. It can be useful to large companies because it requires a large amount of cost, such as the need for treatment and the need for a recovery tower to absorb the collected nitric oxide into water and convert it to nitric acid. There is a problem that is difficult to implement in reality.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve the said problem, the electric solid is first put into constant or hot water, stirred, eluted and removed the water-soluble component, the solid obtained is put into a concentrated aqueous sodium hydroxide solution, and heated, Water was added to the mixture, the carbon dioxide gas was injected to form a carbonate, ammonia water was added thereto to separate the zinc compound and a small amount of the copper compound into a complex salt, and then zinc powder was added to remove the copper compound to obtain a zinc complex compound. It was discovered that zinc can be obtained by heating it to form ammonia, thus completing the present invention.

In other words, it is an object of the present invention to provide a method for recovering zinc from a blast furnace by electricity.

Another object of the present invention is to provide a method for simultaneously recovering sodium carbonate by the above method.

Hereinafter, the present invention will be described in detail.

1 is a side view of an apparatus for producing zinc oxide and iron oxide of the present invention.

Figure 2 is a front view of Figure 1

First of all, the water is evaporated to remove the water-soluble component by adding the dar in a constant or hot water, and then filtered to obtain a solid. Concentrated sodium hydroxide, preferably 50% aqueous sodium hydroxide solution, is added to this solid in equivalent or slightly excess equivalent to the zinc oxide, iron oxide, aluminum oxide, aluminum to be reacted and stirred. The obtained solution is heated in a kiln at 150 to 170 ° C to obtain a concentrate of about 80%. This is reacted in a rotating drum of 350 to 500 ° C., preferably 400 to 500 ° C. The result of this reaction, sodium zincate (Na _{2 2} ZnO), sodium aluminate (NaAlO _2), sodium iron (NaFeO _2), iron oxide, such as sodium silicate (Na ₂ SiO ₃₎ is obtained. This solid is poured into water and carbon dioxide gas is injected while stirring. In this case, commercially available carbon dioxide may be used, but it is economical to filter and purify the gas generated in the process combustion chamber. Reaction with this carbon dioxide gas forms zinc carbonate, sodium carbonate, copper carbonate and the like. This is represented by the following scheme.

Na ₂ ZnO ₂ + 2CO ₂ → Na ₂ CO ₃ + ZnCO ₃

When ammonia water, preferably 15-25% of ammonia water, is added, zinc carbonate and a small amount of copper carbonate form Zn (NH ₃ ) ₄ CO ₃ and Cu (NH ₃ ) ₄ CO ₃ , which are ammonia complex salts. Becomes

Therefore, the ammonia complex salt and sodium carbonate are present in the solution, and the remaining components are precipitated as insoluble matters. The solution is centrifuged to remove the precipitate and only the mother liquor is collected.

In order to remove a small amount of copper ammonium complex salt from the mother liquor, a small amount of zinc powder is added, and copper precipitates as a single metal copper. The precipitate is filtered to remove the precipitate, and when the solution containing zinc complex salt and sodium carbonate is heated at 80 to 110 ° C, preferably 100 to 105 ° C, the zinc complex salt is converted to zinc carbonate and the ammonia water is evaporated. The evaporated ammonia water and water aggregate in a cooling tower and are recovered as ammonia water. At this time, if the amount of evaporation is equivalent to 1/5 of the solution, all ammonia in the complexed compound in the solution is removed.

When all pH-controlled ammonia in the solution is evaporated, zinc carbonate precipitates in the solution, and sodium carbonate is in solution. The solution is filtered to obtain zinc carbonate, which is washed with water and dehydrated to obtain high purity zinc carbonate. At this time, sodium carbonate is obtained in an amount of about 20% increase than sodium hydroxide initially introduced for reaction induction.

The zinc carbonate obtained above is obtained by a known method, that is, high purity zinc oxide when heated, and zinc chloride can be obtained when treated with hydrochloric acid.

EMBODIMENT OF THE INVENTION Hereinafter, the manufacturing apparatus of the iron oxide and zinc oxide of this invention is demonstrated in detail by an accompanying drawing.

1 is a front view of the apparatus of the present invention, and FIG. 2 is a side view thereof. 1 and 2 are longitudinal and transverse cross-sectional views of the device of the invention, with reference numeral 2 designating a rotating drum.

The rotary drum 2 is rotatably supported on the support 6 by one side rotating shaft 4, the rotating shaft 4 of which is connected to a motor 8 as a power source, the motor 8 of which has a built-in reducer It is made in the form of a gear or chain transmission is made with the rotary shaft (4).

The rotating drum 2 has a cover 10 which is a fixed body disposed in an opening opposite to the rotation shaft 4 to cover and protect the inside thereof, and an outer wall made of a firebrick 12 at a predetermined interval on the outer circumferential side thereof. It is enclosed by (14). In addition, it is preferable to form the see-through window 19 in a part of the cover 10, and the see-through window may be any of a known detachable type or a removable type.

The space portion formed between the rotary drum 2 and the refractory brick 12 is a heat passage 17 so that the rotary drum 2 can be heated by a flame generated by the burner 16 disposed at one side thereof. do.

In addition, a wide hopper (I) is disposed below the inner middle portion of the rotating drum (2) and concentrated at about 80% supplied from the supply pipe 20 (in this case, Na ₂ Zn (OH) ₄ ). State), sodium hydroxide, iron hydroxide, aluminum hydroxide, sodium aluminate, NaFeO ₂ , silica, etc. Through the outlet hole 22 is discharged to the inner surface of the rotating drum (2).

In addition, a scraper 24 is disposed on the inner upper side of the rotating drum 2 to scrape and recover the iron oxide and zinc oxide produced by the reaction on the inner wall of the rotating drum, and a scraper below the scraper 24. A recovery container 26 for recovering zinc oxide and iron oxide scraped and dropped by 24 is disposed, and below the recovery container 26, the recovered sodium zincate (Na ₂ ZnO ₂ ) and sodium aluminate (NaAlO _2), sodium iron (NaFeO _2), iron oxide, sodium silicate (Na ₂ SiO _3), the conveyor system 28 in a mixture of such can be sent to the outside are disposed.

In the above, the scraper 24 is rotatably disposed by a lower shaft 30, and a connecting rod 34 having a mass body 32 formed at an end thereof is connected to the shaft 30, and the mass of the mass body 32 is connected thereto. The mass normally remains in a state in which the scraper 24 is in contact with the inner surface of the rotating drum 2, reaches a predetermined amount of zinc oxide and iron oxide recovered by the scraper 24, and falls downward by weight. Should be enough to return to the initial state.

In addition, the conveyor system 28 in the above, but there are a number of types, in the present invention is shown as using a screw conveyor, but is not limited thereto.

In the figure, reference numeral 36 is a chimney, and 38 is a transfer pipe for transferring gas generated in the drum to a known collecting tower (not shown). Numeral 40 denotes a oh collection tank, such as operation of sodium (Na _{2 2} ZnO), sodium aluminate (NaAlO _2), sodium iron (NaFeO _2), iron oxide, sodium silicate (Na ₂ SiO _3).

Referring to the action of the reaction portion of the metal component in the sodium hydroxide and the rust in the present invention is as follows.

Concentrated by about 80% sodium zincate (presumably present in the state of Na ₂ Zn (OH) ₄ ), sodium silicate, iron hydroxide, aluminum hydroxide, sodium aluminate, NaFeO ₂ , silica, etc. The mixed solution of sodium hydroxide and the reaction product and the unreacted product of the metal in the stratum is stored in the hopper I through the supply pipe 20. The stored mixed solution comes into contact with the inner wall of the rotating drum 2 through the outlet hole 22. On the other hand, the heat of the burner 16 flows to the heat passage 17 through the combustion chamber I, and the inner wall of the rotating drum 2 is heated to 400-500 degreeC. On the heated inner wall, the mixed liquid diffuses on the inner surface of the drum 2 by the rotational force of the rotating drum 2 and ascends in the direction of rotation, reacting with sodium hydroxide by heat to heat sodium zincate (Na ₂ ZnO ₂ ) and aluminum. such as sodium (NaAlO _2), sodium iron (NaFeO _2), iron oxide, sodium silicate (Na ₂ SiO ₃₎ is generated. The mixture thus converted is collected downwards by the scraper 24 into the collecting container 26, and the collected iron oxide and zinc oxide are collected in the collecting tank 40 through a conveyor system 28 with a rotating screw. Used for reaction.

On the other hand, the upper portion of one side of the rotating drum is a water gas generated during the reaction, a small amount of sodium hydroxide gas is transferred to the outside through the gas discharge pipe (38). The water gas thus obtained is circulated and reused.

One end of the heat passage 17 is connected to the communication is to control the combustion and temperature.

The rotational speed of the rotating drum 2 is not particularly limited, and depends on the reaction temperature. However, when the reaction temperature is 400 to 500 ° C, a speed of generally 2 to 3 rpm / minute is preferable.

Meanwhile, the cover 10 of FIG. 2 is fixed, and the supply pipe 20, the water gas discharge pipe 38, and the recovery container 26 are fixed to a part of the cover, and the cover is 3 mm or less with the rotating drum 2. You may have a break.

Hereinafter, the present invention will be described more specifically as examples. However, the present invention is not limited to these examples.

Example 1

100 kg of the sample containing 30% of the zinc component in the raw material electric furnace was put in water, sufficiently stirred to elute the water-soluble component, centrifuged to discard the filtrate, and the precipitate was collected. A 50% aqueous sodium hydroxide solution (amount converted into 99% sodium hydroxide: 36 kg) was added thereto, stirred, and concentrated in a kiln at 150 to 160 ° C. so as to have a concentration of about 80%. This solution was used in the apparatus of FIG. 1 to maintain the inner surface temperature of the rotating drum 2 made of Inconel material having a diameter of 3 m, a width of 1.5 m, and a thickness of 8 mm at a temperature of 450 to 500 ° C., and a rotation speed of 2 m. The mixture was reacted while flowing at the speed of 36.5 kg / min through the outlet hole 22 to the inner surface of the rotating drum 2 while maintaining the rpm / min at a rate of 36.5 kg / min. During rotation, it was taken out of the scraper 24 and collected in the collecting container 26 and collected in the collecting tank 40 through the conveyor system 28 with the rotating screw. The resultant zincate mixture of sodium (Na ₂ ZnO _2), sodium aluminate (NaAlO _2), iron sodium (NaFeO _2), iron oxide, sodium silicate (Na ₂ SiO _3), where the reaction heat generated put in 300 liters of water It heats up to high temperature by this. It was stirred sufficiently. After sufficiently injecting carbonic acid gas to convert all of the sodium zincate to carbonate, 50 liters of 20% aqueous ammonia was added and stirred. The reaction solution was collected by filtration to remove the mother solution. A small amount of zinc powder (amount reacting with a small amount of copper salt) is added to the obtained solution, filtered to discard the precipitate, and the solution is heated at 100 ° C to concentrate about 1/5 of the mother liquor. The produced precipitate was collected, washed with water and dried to obtain 54 kg of sodium carbonate. Furthermore, when the residual solution was concentrated under heating at 100 ° C, it became saturated and began to precipitate to obtain 45 kg of sodium carbonate.

The zinc carbonate obtained in this way was analyzed and its purity was 98.5%.

Example 2

The amount of sodium hydroxide in Example 1 was reacted in the same manner as in Example 1 except that 26 kg was used. As a result, 36 kg of zinc carbonate was obtained.

This indicates that sodium hydroxide should be used in an amount corresponding to the amount of zinc.

Example 3

The reaction was carried out in the same manner as in Example 1 except that the temperature of the rotating drum was set at 150 ° C, resulting in 37.8 kg of zinc carbonate.

This indicates that the bonding temperature of sodium hydroxide in the components of the furnace with iron-zinc ferrite should be at least 300 ° C.

Example 4

The carbon dioxide gas injection used in Example 1 was carried out in the same manner except that 10% and 20% of the carbon dioxide was injected. As a result, the recovery rate of zinc carbonate was reduced by the amount of carbon dioxide reduction.

This means that the carbon dioxide gas lacking sodium zincate is not converted to zinc carbonate and is lost.

The present invention is to remove the water-soluble components of the electric furnace Dast, which is a large amount of industrial waste generated by water, and then to react the remaining iron and zinc components with concentrated sodium hydroxide, and to react the resulting sodium zincate with carbon dioxide gas, After forming a complex salt with ammonia water and separating high purity zinc carbonate and sodium carbonate therefrom, the installation cost is low, and even small and medium-sized companies can recover zinc carbonate from the electric furnace daast very economically. In addition, the high purity zinc carbonate thus obtained can be converted into zinc oxide, zinc chloride or the like by a further known method and used as a main raw material for various products.

By the method of the present invention, not only a high value-added zinc compound can be obtained by recycling waste resources, but also a useful invention for preserving the environment.

Claims (4)

The reaction mixture was dissolved in water with dextrose and high concentration of sodium hydroxide in water, and then reacted by adding carbonic acid gas, followed by reaction with ammonia water to obtain a complex of zinc and a solution of sodium carbonate. A high purity zinc carbonate recovery method characterized in that the separation. The method of claim 1 wherein the sodium hydroxide is at a high concentration of at least 50%. 2. The process according to claim 1, wherein the electric mixture of dastro and high concentration of sodium hydroxide and the reaction mixture is concentrated in a kiln of 150 to 170 DEG C, and the concentration is 80% or more. 5. Process according to claim 1 or 4, characterized in that the concentrated reaction mixture is heated at 400 to 500 < 0 > C.