JP3018018B2 - Metal chloride treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating chlorine from metal chlorides generated in a process of treating an etching waste liquid and independently recovering the separated substances.

[0002]

2. Description of the Related Art Generally, an etching waste liquid contains nickel, chromium,
It is regenerated as an etching solution by removing copper, iron and the like.
The metal chloride produced in this process is treated by diluting and stirring the metal chloride with 10 to 100 times the amount of water, followed by filtration to obtain a low chlorine precipitate. Further, in contrast to the above wet treatment, as disclosed in JP-A-50-38967, waste having a high salt content is supplied in a fluidized bed at a blowing speed of a fluidizing gas of 3 m / sec, and the fluidized bed is supplied. An incineration method and the like have been proposed in which the combustion temperature in the inside is maintained at a temperature equal to or higher than the melting point of the waste, and the main part of the salt is discharged together with the exhaust gas.

[0003]

However, the nickel deposit separated from the etching waste liquid is taken as an example.
In the above-mentioned dilution stirring filtration, insoluble iron chloride salts are formed from the deposits of nickel deposits, and chlorine is not completely removed. Also,
A large amount of wastewater containing FeCl ₂ is generated, and when the wastewater is treated, an iron hydroxide precipitate having poor filterability is generated. In addition, it is necessary to transport and discard the iron hydroxide deposit, and the total cost including the treatment is extremely high. On the other hand, waste having a high salt content is supplied in the fluidized bed at a blowing speed of the fluidizing gas of 3 m / sec to maintain the combustion temperature in the fluidized bed above the melting point of the waste, and the main part of the salt is discharged into the exhaust gas. In the method of discharging together with the waste, the combustion temperature in the fluidized bed is kept above the melting point of the waste, so that the consumption of industrial fossil fuel is extremely high, and the fluidization itself is not easy due to the high temperature. Further, when the combustion temperature in the fluidized bed is lowered, the temperature becomes low, and the insoluble iron chloride salt cannot be decomposed, so that the chlorine content in the product is high and the commercial value is low. In addition, this low-temperature processing method has disadvantages such as a high fuel consumption rate and an extremely large amount of exhaust gas even when the nickel deposit is treated with the same moisture. The present invention reliably removes chloride, which is a drawback of these conventional methods, and removes this chloride with low energy consumption, and furthermore, generates less exhaust gas and has a low processing cost. It is an object of the present invention to provide a method for treating a metal chloride which enables the following.

[0004]

According to the present invention, there is provided a method for treating a metal chloride, which comprises removing chlorine from a metal chloride produced as a precipitate in a process of treating an etching waste liquid. Is roasted in a fluidized roasting furnace using a hydrogen-containing fuel or an alkane-based gaseous fuel as a fuel at 500 to 700 ° C., an excess oxygen concentration of 0.5 to 5%, and a residence time in the furnace of 20 minutes or more. The overflow from the roasting furnace and the low iron chloride powder collected in the dust chamber are collected as products, and the gas from the fluidized roasting furnace is cooled and subjected to precipitation treatment with a thickener. Is configured to be collected. Here, the hydrogen-containing fuel refers to a gaseous fuel mixed with hydrogen gas, and the alkane-based gaseous fuel refers to, for example, propane, butane and the like.

[0005]

In the method for treating metal chlorides according to the present invention, the wet powdery sediment generated in the etching waste liquid treatment process is processed in a fluidized roasting furnace using a hydrogen-containing fuel or an alkane-based gaseous fuel as a fuel. ~ 700 ° C, excess oxygen concentration 0.
The roasting process is performed under the conditions of 5 to 5% and the residence time in the furnace is 20 minutes or more. Therefore, the water supplied from the wet powdered sediment and the water generated by the combustion of the hydrogen-containing fuel or the alkane-based gaseous fuel act on the metal chloride to generate HCl, whereby chlorine is separated from the metal chloride. Removed.
Since the combustion temperature is 500 to 700 ° C., the fuel cost and the roasting equipment are not soared, and the excess oxygen concentration is in an appropriate range. Excess oxygen does not promote metal oxidation.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will now be described with reference to the accompanying drawings to provide an understanding of the present invention. FIG. 1 shows a flow chart of a method for treating a metal chloride according to one embodiment of the present invention. As shown in the figure, Table 1 shows the components of the precipitate 10 generated in the treatment of the etching waste liquid as a raw material. .

[0007]

[Table 1]

As shown in Table 1, the precipitate 10 contains Ni powder,
It contains a considerable amount of ferrous chloride powder in addition to iron powder. The sediment 10 is put into a fluidized roasting furnace 12 via a table feeder 11. The fluidized roasting furnace 12 uses propane, which is an example of an alkane-based gaseous fuel, as fuel, and supplies air by a compressor. The propane supply was 0.209 Nm ³ and the air supply was 5.
Excess oxygen is set as 97 Nm ³ , and gas fuel is directly injected into the fluidized bed. And the superficial tower speed is 30-2
At a rate of 00 cm / sec, the precipitate 10 can be roasted at a temperature of 500 to 700 ° C. for 20 to 120 minutes. As a result, the generated moisture and iron chloride react with each other to generate hydrogen chloride and also generate metallic iron. The fluidized roasting furnace 1
2 and the dust collected by the dust chamber 13 consist of dry metal powder 14. The components of the dry metal powder 14 are shown in Table 2, and it can be seen that the chlorine content is extremely small.

[0009]

[Table 2]

The air flow from the dust chamber 13 is cooled and washed by a cooling tower 15 and a washing tower 16, and the cooling liquid and the washing liquid and the dust collected by an electric dust collector 17 in the next step are put into a thickener 18. The supernatant and the sediment are separated. Since the supernatant contains about 15% hydrochloric acid, this is recovered as a resource. The water containing hydrochloric acid can also be used as a replenishing source in the ferrous salt treatment process for producing high-concentration FeCl ₃ from FeCl ₂ , whereby resources can be used more effectively. The gas generated from the electrostatic precipitator 17 contains unrecovered hydrochloric acid. If the gas is diffused into the atmosphere as it is, it will cause pollution. Therefore, the hydrochloric acid is added to the caustic soda aqueous solution (or calcium hydroxide solution) by the detoxification tower 19. The gas that has been absorbed and converted into salt and made harmless is sucked by the blower 20 and released into the atmosphere. Reference numeral 21 denotes a circulation pump. Accordingly, air from which chlorine content has been completely removed is discharged into the atmosphere.

[0011]

As is clear from the above description, the method for treating metal chlorides according to the present invention has almost complete removal of chlorides, so that the method has a great value as a metal resource. Since chlorine is also recovered as hydrochloric acid, resources can be effectively used. Since the processing temperature is relatively low at 500 to 700 ° C., the fuel cost and the cost of the roasting furnace and its accompanying equipment can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart of a method for treating a metal chloride according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Deposit 11 Table feeder 12 Fluid roasting furnace 13 Dust chamber 14 Dry metal powder 15 Cooling tower 16 Washing tower 17 Electric dust collector 18 Thickener 19 Detoxification tower 20 Blower 21 Circulation pump

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Seiichi Kurisu 1-1, Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation Inside Yawata Works (72) Inventor Hideyoshi Sasahara Toba-ku, Tobata-ku, Kitakyushu-shi, Fukuoka No. 1-1, Nippon Steel Corporation Yawata Works (56) References JP-A-50-38967 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23F 1 / 46 F23G 7/00 F27B 15/00

Claims (1)

(57) [Claims] 1. A method for removing chlorine from a metal chloride produced as a deposit in a process of treating an etching waste liquid, wherein the deposit is subjected to a fluid roasting furnace using a hydrogen-containing fuel or an alkane-based gas fuel as a fuel. ~ 700 ° C, excess oxygen concentration 0.5 ~
5%, a roasting treatment at a furnace stay time of 20 minutes or more, the overflow portion of the fluidized roasting furnace and the low iron chloride powder collected in the dust chamber are recovered as products, and the fluidized roasting furnace is recovered. Cooling the gas and precipitating with a thickener and recovering a chlorine-containing liquid from the thickener.