JPS636767B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a method for completely detoxifying and burning cyanide-containing waste liquid from Metsuki factories and coke factories, and more specifically, by mixing cyanide-containing waste liquid and liquid fuel and spraying and burning it as an emulsion fuel, the cyanide component is completely thermally decomposed. It relates to a processing method for detoxification and detoxification. Conventional methods for treating cyanide-containing waste liquid include (1) decomposition through chemical reactions in an aqueous solution such as the alkali chlorine method, thermal hydrolysis method, navy blue method, impact method, and electrolysis method, and (2) boiling and high-temperature combustion. There is a method of decomposition treatment using heat, such as a heat oxidation method and a heating oxidation method. The method (1) using an aqueous solution requires special chemicals and the equipment is large and complicated, making complete treatment difficult. A two-step treatment process called combustion is required, and the equipment is complicated and complete treatment is difficult, so a large amount of fuel is required and it is uneconomical.Also, cyanide-containing waste liquid is not sprayed into the flame or heated in the incinerator. The hot incineration method is uneconomical, requiring complicated conditions and requiring a large amount of fuel, and is difficult to achieve complete treatment in reality. In contrast, in the present invention, the fuel and cyanide-containing waste liquid are sprayed and burned in the form of a uniform emulsion from a burner, so all the cyanide-containing waste liquid is burned in the flame, making it possible to completely incinerate the cyanide component. Since the process can be carried out using a burner, the apparatus is simple and easy to carry out, the use of less fuel is economical, and complete detoxification treatment is possible. That is, the present invention uses (a) 99 to 50% by volume of liquid fuel and (b) 1
and a waste liquid containing ~50% by volume of cyanide,
Complete detoxification treatment of cyanide-containing waste liquid that completely thermally decomposes cyanide components and renders them harmless by spraying and burning water-in-oil emulsion fuel with a viscosity of 50cps or less and an average particle size of 30μ or less at 90℃. It is related to the method. The liquid fuel used in the present invention is, for example, a substance that is difficult to miscible with water and belongs to Class 4 of the Fire Service Act, and representative examples include gasoline, kerosene, light oil, heavy oil, lubricating oil, animal and vegetable oils, and coal tar. Can be done. As the cyanide-containing wastewater, various kinds of wastewater containing CN ions can be used, and typical examples include wastewater containing metal cyanides such as NaCN. From the viewpoints of stability, low viscosity, complete combustibility, etc. of the emulsion to be produced, the ratio of liquid fuel to cyanide-containing wastewater is preferably 50-99% by volume for the former and 1-50% by volume for the latter.
When the moisture content exceeds 50% by volume, cyanide is detected in the exhaust gas. In the present invention, an emulsion fuel is created from the above liquid fuel and cyanide-containing wastewater. In order to create an emulsion, both of the above may be emulsified using a suitable emulsifying device. Examples of emulsifying devices include ultrasonic mixers, dissolvers, motionless mixers,
An appropriate one may be selected from homomixers, gear pumps, turbine pumps, orifices, etc. depending on the state of the fuel and wastewater. The type of emulsion fuel of the present invention is a water-in-oil type from the viewpoint of safety, ignition during combustion, and combustibility. It is essential that the viscosity of the emulsion fuel be 50 cps or less at 90°C. If the viscosity is higher than 50 cps, incomplete combustion occurs and the cyanide cannot be completely processed, resulting in cyanide being detected in the exhaust gas. It is also important that the average particle diameter of the emulsion is 30μ or less.
When the average particle size is larger than 30 μ, cyan content is detected in the exhaust gas. When preparing the emulsion fuel of the present invention, it may not be necessary to use a surfactant, but when a surfactant is used, the stability of the emulsion can be further improved. It is important to use a nonionic surfactant; other anionic or cationic surfactants are not preferred because of poor emulsion stability.
In addition, non-ionic surfactants contain metals that cause ash content when burned, S atoms that cause sulfur oxides, and N atoms that cause nitrogen oxides (NOx). Nonionic surfactants are also unsuitable for such metals,
It is suitable because it does not contain S, N, etc. Furthermore, in preparing the emulsion of the present invention, stabilizers such as polyvinyl alcohol, starch, casein, gelatin, etc., rust preventive agents such as aliphatic phosphoric acid esters, ester amine salts, etc. may be added.
From the viewpoint of pollution control, it is desirable that these additives do not contain sulfur or metals. In the present invention, it is possible to completely thermally decompose the cyan component by spraying and burning the emulsion fuel. As a combustion machine, it can be used in external combustion machines such as boilers and industrial furnaces, and internal combustion machines such as diesels, but it is preferable to use it in external combustion machines. The principle of the complete detoxification treatment of cyanide-containing waste liquid according to the present invention is that, for example, emulsion fuel containing NaCN (sodium cyanide) is completely combusted to produce Na ₂ O, CO ₂ , and NOx.
It is at the point where the cyanide content is completely thermally decomposed. Furthermore, the method of the invention can be carried out easily and inexpensively, without for example changes in the furnace temperature, increases in NOx, hydrocarbons, CO, reductions in efficiency, _negative effects on the burner furnace, etc. The increase in vidine does not contain cyanide, so the exhaust gas can be treated with various dust collectors. According to the treatment method of the present invention, it is possible to almost completely treat the cyan component, and cyan gas is hardly detected in the exhaust gas after combustion, or even if it is detected, it is at most 0.5 to 1 PPM or less. In addition, although the method of the present invention burns cyanide components, the amount of NOx generated is much lower than the amount equivalent to combustion of cyanide components.If you want to further reduce NOx, you can use the two-stage combustion method or the exhaust gas circulation combustion method. Can be used together. Examples of the present invention will be described below. All blending ratios of liquid fuel and cyanide-containing wastewater or water are volume %, and CN is used as cyanide-containing wastewater.
Wastewater containing 1500 PPM (PH=10) was used.
In addition, the analysis methods for cyanide include the JIS K0109 pyridine pyrazolone method for analyzing wastewater, the JIS K0102 detection tube method or JIS K0102 pyridine pyrazolone method for analyzing exhaust gas, and the JIS K0102 pyridine pyrazolone method for analyzing waste gas.
A method was used in which cyanide was extracted using the JIS K0097 nitric acid method and measured using the Corning ion electrode method. Example 1 Kerosene containing 0.3% by weight of the nonionic surfactant sorbitan monostearate and cyanide-containing wastewater were continuously supplied to a pipeline homomixer in the proportions shown in Table 1, and oil with an average particle size of 3.5μ was supplied. A water droplet type emulsion fuel was obtained. This fuel was sprayed in an uncooled furnace equipped with a pressure spray burner at a spray pressure of 5 to 10 kg/cm ² and a spray temperature of 20 to 30 kg/cm 2 .
°C, combustion oil amount 5-7/H, combustion air ratio 1.2-2.0
The results of combustion are shown in Table 1. For comparison, instead of using emulsion combustion, we incinerated cyanide by injecting cyanide-containing wastewater into a kerosene combustion flame, which is one of the conventional methods (hereinafter referred to as cyanide wastewater injection combustion method).
The results for cases (Nos. 5 and 6) are also listed. From Table 1, according to the method of the present invention, cyanide is CO ₂ and NOx.
It can be seen that cyanide is completely decomposed and no cyanide is detected in the combustion waste gas. Also, no cyanide was observed in the vizine.

[Table] Example 2 Stable water-in-oil emulsion fuel was prepared by adding oil and cyanide wastewater in various blending ratios as shown in Table 2, and nonionic surfactants and rust preventives as necessary to a mixer. It was created. In the table, A is sorbitan monooleate, B is polyoxyethylene lauryl ether (HLB = 12), C is aliphatic phosphate ester,
D is an ester amine salt of octylic acid and dipropanolamine, A and B are nonionic surfactants, and C and D are rust preventives. The stability of the emulsion was expressed by the period of time during which it remained stable when the kerosene emulsion was left at room temperature and the C heavy oil emulsion was left at a temperature of 70°C.

[Table] Example 3 A kerosene water-in-oil emulsion fuel (particle size 2 to 5μ) as shown in Table 3 was prepared in the same manner as in Example 1, and it was atomized using the same combustion machine as in Example 1. Temperature 20~30℃, combustion oil amount 5~7/H, combustion air ratio
It was burned at 1.2 to 2.0. From the table, a large amount of cyan gas is observed in the exhaust gas when the moisture content exceeds 50%.

[Table] Example 4 Water-in-oil emulsion fuel (average particle size 2 to 5μ) of heavy oil A as shown in Table 4 was prepared in the same manner as in Example 1.
It was created. This emulsion fuel was heated in the same combustion machine as in Example 1, at a spray temperature of 20 to 30°C and a combustion oil amount of 5 to 50°C.
7/H and combustion air ratio of 1.2 to 1.7, no cyanide was detected in the combustion exhaust gas. Furthermore, no cyanide was observed in the vizine.

【table】

[Table] Example 5 In the same manner as in Example 1, water-in-oil emulsion fuels of kerosene having different average particle sizes as shown in Table 5 were prepared, and they were used in the same combustor and combustion conditions as in Example 1. When the emulsion was burned, even if the viscosity of the emulsion was low, if the average particle size exceeded 30μ, cyan gas was observed to be generated in the exhaust gas.

[Table] Example 6 Water-in-oil emulsion fuel was prepared by adding 30 parts of cyan waste water or water and various surfactants to 70 parts of the fuel listed in Table 6 using a mixer, and its stability was investigated. The stability of kerosene and heavy oil A is determined by leaving it at room temperature, and the stability of heavy oil B is determined by leaving it at room temperature.
It was left at a temperature of 50°C and examined. In the stability evaluation, an x indicates that the product immediately separated into two layers: an oil layer and an aqueous layer. Table 6 shows that when nonionic surfactants are used, the emulsion stability is better than that of cyanide wastewater and fuel, but when cationic and anionic surfactants are used, the emulsion stability is better than that of cyanide wastewater and fuel. turns out to be bad.

[Table] Example 7 Heavy oil C (15 cps/90°C, sulfur content = 2.5%, nitrogen content 0.23%) heated to about 50°C and cyanide wastewater at about 30°C were fed into a propeller agitator (variable rotation speed). The mixture was mixed to obtain water-in-oil emulsion fuels having various particle sizes as shown in the table below. This water-in-oil emulsion fuel was used in the same combustion machine as in Example 1 at a spray temperature of 90 to 100°C and a combustion oil amount of 5.
~7/H and combustion air ratio of 1.2 to 1.7, cyan gas was observed in the combustion exhaust gas when the average particle size of the emulsion exceeded 30μ. For comparison, the results obtained when cyanide wastewater was combusted by the same cyanide wastewater injection combustion method as in Example 1 are also shown.

[Table] Example 8 A water-in-oil emulsion fuel was prepared in the same manner as in Example 7 using C heavy oil and/or machine oil, cyan waste water, and nonionic surfactant (sorbitan sesquistearate) at 0.03% per oil. was prepared and burned in the same combustion machine as in Example 1 at a spray temperature of 90 to 100°C, a combustion oil amount of 5 to 7/H, and a combustion air ratio of 1.2 to 1.7. Cyan gas was detected in the combustion exhaust gas when the fuel consumption exceeded 50 cps. The results are shown in Table 8.

[Table] Example 9 In the same manner as in Example 7, oil mixed with heavy oil A and heavy oil B, cyan waste water, and a nonionic surfactant (sorbitan sesquistearate) were added per oil.
A water-in-oil emulsion fuel was prepared using 0.05%. The ratio of heavy oil A to heavy oil B was adjusted so that the viscosity of the resulting emulsion would be the value shown in Table 9. Table 9 shows the results of burning the obtained emulsion fuel in the same combustor as in Example 1 under the same conditions. When the viscosity of emulsion fuel is 90℃
Cyan gas was observed in the combustion exhaust gas when it exceeded 50 cps.

【table】

[Table] Comparative example 1 Nonionic surfactant (polyethylene oxide nonyl phenyl ether HLB=14) 0.3% by weight
Continuously feed cyanide-containing wastewater and A heavy oil containing
A 4.8μ oil-in-water emulsion fuel was obtained. This oil-in-water type emulsion fuel was used in Example 1.
When it was burned in the same combustion machine under the same conditions, a small amount of cyanide was detected. The results are shown in Table 10.

【table】

Claims (1)

[Scope of Claims] 1 (a) A liquid fuel containing 99 to 50% by volume of liquid fuel and (b) a waste liquid containing 1 to 50% by volume of cyanide, with a viscosity of 50 cps or less at 90°C and an average A method for completely detoxifying cyanide-containing waste liquid, which is characterized by thermally decomposing cyanide components by spraying and burning a water-in-oil emulsion fuel with a particle size of 30μ or less.