KR20000021019A - Preparation method of zinc sulfate and(or) ferrous sulfate without containing chlorine from electric furnace dust or zinc ash - Google Patents

Abstract

PURPOSE: A preparation method of zinc sulfate and(or) ferrous sulfate without containing a chlorine component by treating dust of electric furnace or zinc ash with zinc sulfate in the presence of a reducing agent and apparatus thereof are provided which can produce easily and economically and reduce waste for dust of electric furnace. CONSTITUTION: A process for producing zinc sulfate and(or) ferric sulfate without containing a chlorine component comprises: (a)mixing electric dust or zinc ash and zinc scrap with a reducing agent selected from mineral oil, heavy oil, bunker C oil, lubricating oil, and waste oil and crushing; (b)reacting with concentrated sulfuric acid at 300°C; (c)exhausting produced hydrogen chloride, aqueous vapor, hydrogen gas etc.; (d)producing zinc sulfate and ferric sulfate; (e)precipitating FeSO4.7H2O by adding with water; and (f)separating zinc sulfate by filtering.

Description

PROCESS FOR PRODUCING CHLORINE-FREE ZINC SULFATE AND FERROUS SULFATE FROM DUST OF ELECTRIC FURNACE OR ZINC DUST

The present invention relates to a method for producing zinc sulfate and ferrous sulfate, which do not contain a chlorine component, from an electric dust or zinc material with high purity. In more detail, zinc sulfate and / or sulfuric acid containing no chlorine components are treated with zinc sulfate and zinc sulfate in the presence of a reducing agent by treating raw materials such as zinc and zinc scrap generated in the furnace and zinc plating by-product generated during melting of scrap metal. It relates to a method of producing iron.

Up to now, large amounts of electricity, such as dung or zinc, cannot be used as it is, so they have been disposed of through special industrial waste companies or mixed with asphalt mortar. However, due to various heavy metals from leachate, the soil is depleted. When the solution containing the leached heavy metal is dried, the fine powder is scattered and adversely affects the human body, which is a social problem.

Furnace Dast is produced by the evaporation of scrap metals such as scrap cars in a high-temperature electric furnace at 1800 ℃. The components of the furnace vary depending on the type of scrap metal and the processing company. I knew that.

Iron (Fe): 20-30%, Zinc (Zn): 15-30%, Chlorine (Cl): 2-6%,

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

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

In order to solve this problem, the present inventors have applied for a number of patents relating to a method for recovering zinc from electric dust or zinc (see Patent Application Nos. 98-12296, 98-15857, etc.). However, the present invention can produce expensive metal zinc or zinc compound by treating the blast furnace with electricity, but it is difficult to carry out when the most expensive equipment is required or when various processes are required and it is economically difficult. have.

However, according to a recent investigation, even if it is intended to produce zinc sulfate for use in electroplating of the furnace or zinc material, or to recover zinc by electrolysis, the amount of chlorine contained in the furnace or zinc material is increased. Should be less than 0.1%, it was found that the removal of this chlorine is not easy to use it.

That is, until now, zinc materials and the like generated during dry plating have been heated at a high temperature of 1,000 to 1,300 ° C. to remove chlorine components contained in zinc materials by pyrolysis and evaporation with zinc chloride, ammonium chloride and the like.

In addition, since most of the chlorine components contained in the electric furnace are present in sodium chloride, potassium chloride, etc., the high temperature pyrolysis method has been used, but it is not possible to make the chlorine residual less than 0.1% which is the standard of the residual amount of chlorine.

In the electric furnace, a large amount of zinc and iron are contained, and the zinc component (25% in average) in the electric furnace is converted into zinc sulfate, followed by electrolysis of zinc sulfate to obtain zinc with high purity. However, when sulfuric acid is directly reacted with a blast furnace or zinc material in order to obtain zinc sulphate, in the case of an electric furnace, iron is present as ferric oxide (Fe ₂ O ₃ ) and ferric oxide. This sulfuric acid reacts to form ferric sulfate [Fe ₂ (SO ₄ )]. That is, since the furnace raw material component exists in the state of a zinc iron ferrite compound, zinc oxide, and ferric oxide, the reaction of the electric furnace with concentrated sulfuric acid causes zinc sulfate, ferric sulfate [Fe ₂ ( SO ₄ ) ₃ ] and a mixture of molecules in the state of the iron sulfate polymer [Fe ₂ (SO ₄ ) .Fe (OH) ₂ .X _n ] state, and since the mixture is in a gel state, purification of the solution is very difficult to treat. Is almost impossible, and even if possible, separate processes and costs were enormous and could not be actually processed.

The inventors have investigated the amount and quality of zinc compounds required in the industry, and there is a great demand for zinc sulfate, but despite the shortage of supply, chlorine content in the recovered zinc sulfate is 0.1 by the known method. The rule below% was not satisfied. In other words, it is confirmed that it cannot be prepared by directly reacting the mist with concentrated sulfuric acid, and zinc sulfate can be easily prepared by constructing hydrogen chloride gas by reacting the mist or zinc material with concentrated sulfuric acid by adding a high-temperature pyrolytic reducing agent. It has been found that the present invention has been completed.

That is, an object of the present invention is to provide a method for recovering zinc sulfate and / or ferrous sulfate, which do not contain a chlorine component, from an electric dust or zinc material.

Hereinafter, the present invention will be described in detail.

Fig. 1 shows an apparatus for producing ferrous sulfate and / or zinc sulfate which does not contain chlorine components from a dust or zinc material according to the present invention.

2 is a plan view of the diaphragm of FIG.

Chlorine components present in the electric furnaces and zinc materials include compounds such as zinc chloride (ZnCl ₂ ), ammonium chloride (NH ₄ Cl), sodium chloride (NaCl), potassium chloride (KCl), and iron chloride (FeCl ₂ ) as described above. It is impossible to remove chlorine completely from heat treatment at 1,000 ~ 1,300 ℃ because

Therefore, concentrated sulfuric acid is directly stirred and mixed with these materials, and heated at about 300 ° C. to discharge anhydrous hydrochloric acid gas. In particular, electric furnace dust contains 20 to 35% by weight of zinc and 20 to 30% by weight of iron. In addition, 1 to 8% by weight of lead, 0.1 to 0.4% by weight of copper, 0.01 to 0.1% by weight of cadmium, 0.01 to 0.5% by weight of nickel, and 2 to 6% by weight of chlorine, Concentrated sulfuric acid alone in the material of this configuration can not be removed chlorine completely. Therefore, when a high-temperature pyrolytic reducing agent is added to these materials and reacted with concentrated sulfuric acid, the chlorine component is converted into hydrochloric acid gas and discharged.

In addition, since the iron component is present in the state of ferric oxide (Fe ₂ O ₃ ) during the reaction of sulfuric acid, it is converted into the state of ferric sulfate [Fe ₂ (SO ₄ )] when reacted with sulfuric acid. Water was added to the prepared raw material and dissolved with water, residue, and the resultant filterability was poor at the time of separation, and the elution solution could not be separated because of no filtering, and crystal separation of zinc sulfate and ferric sulfate salt was impossible even if separated. Done.

In order to improve the reactivity and physical properties of these materials, a high temperature pyrolytic reducing agent, for example, a material capable of generating hydrogen during high temperature reaction, more specifically mineral oil such as mineral oil, heavy oil, bunker C oil, lubricating oil, waste oil, etc. When 1-15% by weight is uniformly mixed with the raw material of the furnace, and concentrated sulfuric acid is added thereto while stirring, the reaction temperature is about 300 ° C. by exothermic reaction. Decomposed carbon and hydrogen are combined with oxygen in the reactor and converted into carbon monoxide, carbon dioxide and water, and some of them remain, and the ferric sulfate oxygen and hydrogen are converted to ferrous sulfate salts. It reacts with chlorine to form hydrogen chloride gas and is released.

The reaction is represented by the following scheme.

2C + O ₂ → 2CO

2CO + O ₂ → 2CO ₂

3Fe ₂ O ₃ + 2H ₂ + 6H ₂ SO ₄ → 6FeSO ₄ + 9H ₂ O

ZnO + H ₂ SO ₄ → ZnSO ₄ + H ₂ O

2NaCl + H ₂ SO ₄ → Na ₂ SO ₄ + 2HCl

2KCl + H ₂ SO ₄ → K ₂ SO ₄ + 2HCl

FeCl ₂ + H ₂ SO ₄ → FeSO ₄ + 2HCl

The zinc sulfate and ferrous sulfate obtained in the above reaction have good filterability and are very good in workability when eluted with water, filtered and separated and purified. In addition, the synthesized zinc sulfate and ferrous sulfate are separated by precipitation of ferrous sulfate in the form of a hexate salt, that is, FeSO ₄ · 7H ₂ O at 25 ° C. in an aqueous solution at a concentration of 45% by weight.

That is, the iron component contained in the raw material of zinc in a large amount of zinc is converted to ferrous sulfate, water is added thereto, crystallized into ferric sulfate hexate, separated from the zinc sulfate solution, and zinc sulfate and iron sulfate are highly purified. It can be obtained easily.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a schematic view showing an apparatus for recovering zinc sulfate and ferrous sulfate from an electric furnace rust or zinc material according to the present invention.

The apparatus of the present invention relates to an apparatus for recovering zinc sulfate or ferrous sulfate that does not contain a chlorine component from an electric dust or zinc material.

A hopper 21 for storing electric furnace dust or zinc material as a raw material, a reducing agent tank 22, and a transfer screw 24 for introducing the electric furnace dust or zinc material and the reducing agent into the reaction kiln 1;

Rollers 12 and 12 'for supporting the reaction kiln 1 on the support 11, support shafts 13 and 13' of the rotary reaction kiln 1, and a driving device 17 for rotating the reaction kiln 1; ;

It is connected to the conveying screw 24 and has a plurality of compartments 16, 16 ′,... Partitioned inside by a plurality of diaphragms 14, 14 ′. Sulfuric acid supply pipe 32 extending from the sulfuric acid tank 30 and spraying concentrated sulfuric acid into the second compartment 16 'and the third compartment 16 ", for mixing and grinding the raw materials introduced into the first reaction kiln 1 A first reaction kiln (1) consisting of an iron ball (15);

Connection pipe 41 and the exhaust gas absorption tower for transferring the gas discharged from the first reaction kiln (1);

A pipe 42 and a transfer screw 23 'connecting to a collection tank 40 and a second reaction kiln 1' containing a reaction mixture containing an unreacted mixture discharged from the first reaction kiln 1;

A discharge port 918 which is connected to the conveying screw 23 'and has a plurality of compartments 16 and 16' inside which are partitioned by a plurality of diaphragms 14, 14 '... ) And a second reaction kiln 1 'consisting of iron balls 15 for mixing and pulverizing the raw materials introduced into the reaction kiln;

Storage tank 60 for recovering the reaction product in the second reaction kiln 1 '

It consists of a device for recovering zinc sulfate or ferrous sulfate that does not contain a chlorine component.

Hereinafter, the operation of the apparatus according to the present invention will be described in detail.

In the hopper 21, the raw material of the electric furnace, a rust or zinc material, is transferred from the reducing agent storage tank 11 to the first compartment 16 of the reaction kiln 1 through the screw 24. The hopper and the reducing agent tank is attached to the valve 23 so that the required amount. In addition, when the reaction is a continuous reaction, the raw material and the reducing agent can be attached to the automatic controller. At the rear end of the screw 6, a driving device 25 for operating the screw 24 is attached. The first reaction kiln 1 is rotated by a motor 17 connected to the drive device 24, and the reaction kiln is supported on the support rollers 12, 12 ′ on the support 11. 13 ') to be rotationally supported. The interior of the first reaction kiln (1) consists of at least two, preferably three or more compartments (16) (16 ') 16 "', which compartments (14) (14 '). .. are attached along the inner circumference of the reaction kiln by welding or the like to form a compartment, and the diaphragm 14, 14 ", ..., as shown in Figure 2, a plurality of crescent or rectangular, square, etc. 14H (14H ') ..... is formed in the shape of a. Each compartment 16 (16 ') .... contains a plurality of steel balls (15). Here, the iron ball is an iron sphere, preferably 5 to 10 cm in diameter, and the number of iron balls accommodated in the reaction kiln is smaller in number than the central axis of the reaction kiln. Allow only up to a centimeter drop. The reason is that when the reaction kiln rotates, the iron ball 15 accommodated inside the kiln by the rotation does not damage the sulfuric acid pipe 32 extending into the reaction kiln 1 by the dropping of the iron ball. .

When the reaction kiln (1) is rotated, the iron ball 15 is lowered by gravity to rotate the charged mixture is pulverized and mixed, the iron ball 15 is maintained as it is. The mixture pulverized in the first compartment 16 is transferred to the second compartment 16 'through the small holes 16H, 16H' of the diaphragm, and the second compartment 16 'and the third compartment. In 16 ″, the second compartment 16 ′ and the first compartment of the first reaction kiln 1 are connected via a pipe 32 connected through a valve 31 in the sulfuric acid tank 30 installed outside the reaction kiln 1. The ends of the pipes 32 are closed so that they are sprayed from the three compartments 16 ", and a plurality of spray holes 32 'and 32" are provided in the portions extending to the second compartment 16' and the third compartment 16 ". ) Is excreted. In the first reaction kiln, when the mixed pulverized product of the darst or the zinc material and the reducing agent is reacted with concentrated sulfuric acid, the temperature of the reaction kiln is increased to about 300 ° C. by exothermic reaction. It should be made of material that can be used, for example Inconal, stainless steel, etc.

The reaction product in which the reaction is completed in the first reaction kiln 1 is discharged through the reaction kiln outlet 18 and transferred to the collection tower 40. In the product mixture, gaseous components such as hydrogen chloride gas, carbon monoxide, carbon dioxide, water vapor, etc. are neutralized by a sodium hydroxide sprayed through an absorption fan 43 via a pipe 41 connected to an upper portion of the collection tower 40. Is processed in The neutralization tower 50 is a solution such as sodium hydroxide is sprayed through a sprayer 52 through a transfer pump 51 and processed, and the treated liquid and gas are transferred to an external storage tank (not shown). Meanwhile, zinc sulfate and ferrous sulfate transferred to the collection tank 40 are transferred to the second reaction kiln 1 'through the screw 23'. The structure of the second reaction kiln 2 is the same as that of the first reaction kiln 1 except that sulfuric acid is induced in the first reaction kiln 1 and sprayed to the reaction kiln is not installed. The reaction product mixture from the outlet 18 'of the second reaction kiln 1' is transferred to the collection tank 40, and the collection tank 40 has a gas mixture such as hydrogen chloride gas and steam at the top of the pipe. Discharge treatment is carried out through a pipe 42 connected to 41, and the reaction product zinc sulfate and ferrous sulfate are transferred to the lower storage tank 60. In order to make the reaction more complete, it is preferable to have two or more reaction kilns identical to the second reaction kilns. Moreover, it is preferable to provide a well-known cyclone and a fractionation tower in the discharge pipe 41 and 42, and since this technique is a conventional technique, description is abbreviate | omitted about installation of such a tower in this invention.

The size of the reaction kiln is not particularly limited, and for example, the ratio of diameter and length is preferably about 1.2: 3.0.

The rotational speed of the first reaction kiln is not particularly limited, but if it is too fast, the reaction may not be performed smoothly. If it is too slow, the reaction may be well performed, but it may not be economical. In addition, in the case where a plurality of second reaction kilns are installed, the rotation speed may be increased. It is also affected by the size of each reaction kiln. In general, the rotational speed of the reaction kiln is preferably about 15 to 20 rpm according to the inventors' experience. The reaction time depends on the rotational speed of the reaction kiln, but in general, when the rotational speed of the first reaction kiln is within the above range, the reaction time is sufficient to be about 15 to 20 minutes, and the reaction of the second reaction kiln is initiated. It is preferable to start from the point where the mixture of the reaction mixture and the unreacted substance is transferred to the second reaction kiln.

When water is added so that the zinc sulfate and ferrous sulfate obtained in the reaction are 45 wt% at about 25 ° C. as described above, the ferrous sulfate becomes ferrous sulfate heptahydrate and precipitates and is separated from zinc sulfate. To obtain zinc sulfate and ferrous sulfate.

Hereinafter, an Example is given and this invention is demonstrated concretely. However, the present invention is not limited by these examples.

Example 1

1 kg of the sample containing 25% of zinc, 30% of iron, 5% of lead, 5% of chlorine, and 70 g of waste lubricating oil in the raw material electric furnace, the hopper 21 and the reducing agent of FIG. The storage tank 22 was placed in the first reaction kiln 1 containing a plurality of iron balls through the screw 24, and the reaction kiln 1 was rotated at 17 rpm for 5 minutes. While continuously rotating the reaction kiln 1, 1 kg of 97% concentrated sulfuric acid stored in the sulfuric acid tank 30 is connected to the second compartment 16 'and the third deletion 16 "in the first reaction kiln. The reaction temperature was maintained at 300 ° C. for 20 minutes while the reaction temperature was maintained at 300 ° C. The second reaction kiln (1 ′) was operated about 10 minutes after the start of the reaction of the first reaction kiln (1), The reaction was terminated after about 15 minutes.

Then, the mixture containing zinc sulfate, ferrous sulfate and a small amount of residue recovered in the storage tank 60 was taken out and placed in a separate container, and water was poured while stirring slowly to obtain an average concentration of 45%. After about 20 minutes, ferrous sulfate precipitated and separated into its seven hydrochloride, and zinc sulfate remained as a filtrate. This was filtered to separate zinc sulfate and ferrous sulfate. The zinc sulfate solution was dried to obtain 1100 g of zinc sulfate hexahydrate and 1520 g of ferrous sulfate.

As a result of analyzing the obtained zinc sulfate, the purity was 99.95% and the chlorine content was 0.03%.

Comparative Example 1

Zinc sulfate and ferric sulfate were obtained in the same manner as in Example 1, except that mineral oil as a reducing agent was not used in Example 1. This mixture could not be separated and analyzed, and the chlorine content was 0.5%.

Example 2

Using the same apparatus as in Example 1, 1 kg of zinc material containing 60% of zinc, 2% of iron, 3% of ammonium chloride, 1.98% of chlorine, etc., 50 g of bunker C oil, and 1.2 Kg of concentrated sulfuric acid were added. The reaction was carried out in the same manner as in Example 1 except that it was used.

Then, the mixture containing zinc sulfate, ferrous sulfate and a small amount of residue recovered in the storage tank 60 was taken out and placed in a separate container, poured with water while gradually stirring to an average concentration of 45%, and filtered. A filtrate was obtained. 40 g of potassium permanganate and 10 g of potassium chlorate were added to the obtained filtrate, and the mixture was slowly stirred for about 10 minutes, and then filtered to obtain a filtrate, which was dried to give 2649 g of zinc sulfate hexahydrate.

As a result of analyzing the obtained zinc sulfate, the purity was 99.95% and the chlorine content was 0.05%.

As described above, according to the present invention, zinc sulfate and / or ferrous sulfate, which do not contain expensive chlorine components, can be easily and economically obtained by treating the dar and zinc materials with electricity that has not been treated so far. In addition, the present invention provides a revolutionary effective invention that significantly reduces the waste amount of the electric furnace.

Claims (4)

In the method for recovering zinc sulfate or ferrous sulfate containing no chlorine component from electric dust or zinc material, the reducing agent selected from electric dust or zinc material and mineral oil, heavy oil, bunker C oil, lubricating oil and waste oil. The mixture was pulverized, and concentrated sulfuric acid was added to react with the mixture at about 300 ° C., and the resulting hydrogen chloride, water vapor, hydrogen gas, and the like were discharged, and the resulting zinc sulfate and ferrous sulfate were collected. A method for recovering zinc sulfate and ferrous sulfate containing no chlorine, characterized by depositing ferrous iron, filtering and drying the filtrate zinc sulfate solution. In the apparatus for recovering zinc sulfate or ferrous sulfate containing no chlorine component from the darst or zinc material by electric, A transfer screw for introducing a reducing agent into a reaction kiln from a hopper for introducing a raw material of a dart or zinc material as a raw material, a reducing agent tank for introducing a reducing agent; A roller and a rotation support shaft for supporting rotation of the reaction kiln on the support, and a driving device for rotating the reaction kiln; A sulfuric acid supply pipe connected to the transfer screw and having a plurality of compartments defined by a plurality of diaphragms therein, extending from an external sulfuric acid tank to spray sulfuric acid into a second compartment and a third compartment, a raw material introduced into a reaction kiln A first reaction kiln composed of iron balls for mixed grinding; A connecting pipe and an exhaust gas absorption tower for transferring the gas discharged from the first reaction kiln; A pipe and a transfer screw connected to a collection tank and a second reaction kiln for transferring a reaction mixture containing an unreacted mixture discharged from the first reaction kiln; A second reaction kiln connected to the transfer screw and having a plurality of compartments defined by a plurality of diaphragms therein, the outlet for transferring the reactants and an iron ball for mixing and grinding the raw materials introduced into the reaction kiln; Reservoir tank to recover reaction products from the second reaction kiln Apparatus for recovering zinc sulfate or ferrous sulfate that do not contain a chlorine component consisting of. The device of claim 2, wherein there are at least two second reaction kilns. 4. An apparatus according to claim 2 or 3, wherein there are three or more diaphragms in the reaction kiln.