A treatment method for desulfurization waste liquid of coke oven gas

Abstract

The present invention relates to the technical field of coking, and particularly to a method for treating waste liquid from coke oven gas desulfurization, which includes: A) mixing the waste liquid from coke oven gas desulfurization with sulfur dioxide gas until the pH value is 6.0 - 6.2, reacting, and filtering to obtain a first filtrate and a sulfur-containing precipitate; B) the first filtrate enters a micro-electrolysis reactor filled with iron-carbon active raw materials for catalytic oxidation reaction; C) mixing the reaction product liquid with hydrogen peroxide solution and filtering to obtain Fe4[Fe(CN)6]3 crystals, Fe(OH)3 precipitate and a second filtrate; D) detecting the content of SCN ‑ in the second filtrate. When the content is less than 180 g / L, the pH value is adjusted to 10 - 10.5 with sodium hydroxide solution and recycled to the coke oven gas desulfurization system; when it is above 180 g / L, it is mixed with ammonia water solution and filtered to obtain NH4SCN solid and treated water body. The method can effectively purify the waste liquid from coke oven gas desulfurization.

Description

Technical Field

[0001] The present invention relates to the technical field of coking, and in particular to a method for treating waste liquid from coke oven gas desulfurization. Background Art

[0002] Wet oxidation method and chemical absorption method are often used in coke oven gas desulfurization. In the wet oxidation method, with the catalytic action of the oxygen carrier in the absorption solution, the absorbed H2S is oxidized into sulfur, so that the absorption solution can be regenerated. The chemical absorption method uses a weakly alkaline solution as the absorbent to chemically react with H2S to form a compound. When the temperature of the rich absorption liquid rises and the pressure drops, the compound decomposes to release H2S, mainly the vacuum carbonate process. The vacuum carbonate process is used for coke oven gas desulfurization in Pangang. During operation, due to the presence of thiocyanide in the gas, it cannot be removed in time when entering the desulfurization liquid, resulting in problems such as equipment blockage, reduced desulfurization effect, and high cost. At present, although iron salts are added for removal, the effect is poor, and only CN - can be removed, and the solution cannot be purified, showing black-red color, which is easy to cause system blockage, and further deteriorates the desulfurization effect. Therefore, it is urgent to study a removal process that is highly efficient, economical, short-process, circularly removes, recovers and utilizes resources, and has low investment. Summary of the Invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a method for treating waste liquid from coke oven gas desulfurization, which can effectively purify the waste liquid from coke oven gas desulfurization.

[0004] The present invention provides a method for treating waste liquid from coke oven gas desulfurization, including the following steps:

[0005] A) Mix the waste liquid from coke oven gas desulfurization with sulfur dioxide gas until the pH value is 6.0 - 6.2, react, and filter the obtained reaction feed liquid to obtain a first filtrate and a sulfur-containing precipitate;

[0006] B) The first filtrate enters a micro-electrolysis reactor for catalytic oxidation reaction; the micro-electrolysis reactor is filled with iron-carbon active raw materials;

[0007] C) Mix the product feed liquid after the catalytic oxidation reaction with hydrogen peroxide solution, filter to obtain Fe4[Fe(CN)6]3 crystals, Fe(OH)3 precipitate and a second filtrate;

[0008] D) Detect the content of SCN - in the second filtrate;

[0009] When the content of SCN - in the second filtrate is less than 180 g / L, adjust the pH value of the second filtrate to 10 - 10.5 with sodium hydroxide solution and reuse it in the coke oven gas desulfurization system;

[0010] When the content of SCN - in the second filtrate is above 180 g / L, it is mixed with an ammonia water solution, and after filtration, NH4SCN solid and treated water body are obtained.

[0011] Preferably, in step A), in the coke oven gas desulfurization waste liquid, the content of K + is 500 - 900 mg / L, the content of Na + is 25 - 80 g / L, the content of S 2- is 10 - 15 g / L, the content of S2O3 2- is 6 - 15 g / L, the content of SCN- is 140 - 240 g / L, the content of CN - is 500 - 4000 mg / L, the content of Fe 2+ is 20 - 100 mg / L, the content of Mn 2+ is < 10 mg / L, the content of COD is 2000 - 5000 mg / L, and the content of ammonia nitrogen is < 500 mg / L.

[0012] Preferably, in step A), the temperature of the reaction is 20 - 30 °C and the time is 68 - 76 h.

[0013] Preferably, in step A), the filtration method is plate and frame filtration, and the filtration accuracy is 0.5 - 1 μm.

[0014] Preferably, in step B), the iron-carbon active raw material includes blast furnace waste pig iron blocks and columnar activated carbon; or the iron-carbon active raw material includes ellipsoidal iron-carbon material;

[0015] The mass content of Fe in the blast furnace waste pig iron blocks is 93% - 94%;

[0016] The mass content of C in the columnar activated carbon is 4% - 5%;

[0017] In the iron-carbon active raw material, the mass ratio of Fe to C is 8.8 - 9.2:1.

[0018] Preferably, in step B), the residence time of the first filtrate in the micro-electrolysis reactor is 20 - 25 min;

[0019] The temperature of the catalytic oxidation reaction is 25 - 30 °C.

[0020] Preferably, in step B), the mass ratio of the first filtrate to the iron-carbon active raw material is 80 - 100:1.

[0021] Preferably, in step C), the concentration of the hydrogen peroxide solution is 0.05 - 0.1 g / L;

[0022] The molar ratio of the hydrogen peroxide to Fe in the product liquid material 2+ is 0.15 - 0.3:1.

[0023] Preferably, in step D), the aqueous ammonia solution is the ammonia-containing wastewater discharged from the ammonia distillation system;

[0024] The concentration of the aqueous ammonia solution is 1% - 3%;

[0025] The molar ratio of NH in the aqueous ammonia solution 4+ to SCN in the second filtrate - is 1.0 - 1.2:1;

[0026] The temperature of the aqueous ammonia solution is 50 - 60 °C.

[0027] Preferably, in step D), the filtration precision is 0.1 - 0.2 μm.

[0028] The present invention provides a method for treating the desulfurization waste liquid of coke oven gas, comprising the following steps: A) Mixing the desulfurization waste liquid of coke oven gas with sulfur dioxide gas until the pH value is 6.0 - 6.2, reacting, filtering the obtained reaction liquid material to obtain a first filtrate and a sulfur-containing precipitate; B) Feeding the first filtrate into a micro-electrolysis reactor for catalytic oxidation reaction; the micro-electrolysis reactor is filled with iron-carbon active raw materials; C) Mixing the product liquid material after the catalytic oxidation reaction with a hydrogen peroxide solution, filtering to obtain Fe4[Fe(CN)6]3 crystals, Fe(OH)3 precipitate and a second filtrate; D) Detecting the content of SCN in the second filtrate - When the content of SCN in the second filtrate - is less than 180 g / L, adjusting the pH value of the second filtrate to 10 - 10.5 with sodium hydroxide solution and recycling it to the coke oven gas desulfurization system; when the content of SCN in the second filtrate - is above 180 g / L, mixing it with an aqueous ammonia solution, filtering to obtain NH4SCN solid and treated water body. The treatment method provided by the present invention can effectively purify the desulfurization waste liquid of coke oven gas, and effectively solve the problems of difficult external discharge treatment, high cost and high risk of the desulfurization waste liquid. Specific Embodiments

[0029] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] The present invention provides a method for treating waste liquid from coke oven gas desulfurization, comprising the following steps:

[0031] A) Mix the waste liquid from coke oven gas desulfurization with sulfur dioxide gas until the pH value is 6.0 - 6.2, carry out a reaction, filter the obtained reaction liquid to obtain a first filtrate and a sulfur-containing precipitate;

[0032] B) The first filtrate enters a micro-electrolysis reactor for catalytic oxidation reaction; the micro-electrolysis reactor is filled with iron-carbon active raw materials;

[0033] C) Mix the product liquid after the catalytic oxidation reaction with hydrogen peroxide solution, and after filtration, obtain Fe4[Fe(CN)6]3 crystals, Fe(OH)3 precipitate and a second filtrate;

[0034] D) Detect the content of SCN - in the second filtrate;

[0035] When the content of SCN - in the second filtrate is less than 180 g / L, adjust the pH value of the second filtrate to 10 - 10.5 with sodium hydroxide solution and reuse it in the coke oven gas desulfurization system;

[0036] When the content of SCN - in the second filtrate is above 180 g / L, mix it with ammonia water solution, and after filtration, obtain NH4SCN solid and treated water body.

[0037] The present invention first mixes the waste liquid from coke oven gas desulfurization with sulfur dioxide gas until the pH value is 6.0 - 6.2, carries out a reaction, and filters the obtained reaction liquid to obtain a first filtrate and a sulfur-containing precipitate.

[0038] In certain embodiments of the present invention, the waste liquid from coke oven gas desulfurization is the waste liquid from the vacuum carbonate desulfurization process. In certain embodiments of the present invention, in the waste liquid from coke oven gas desulfurization, the content of K + is 500 - 900 mg / L, the content of Na + is 25 - 80 g / L, the content of S 2- is 10 - 15 g / L, the content of S2O3 2- is 6 - 15 g / L, the content of SCN - is 140 - 240 g / L, the content of CN - is 500 - 4000 mg / L, the content of Fe 2+ is 20 - 100 mg / L, the content of Mn 2+ is < 10 mg / L, the content of COD is 2000 - 5000 mg / L, and the content of ammonia nitrogen is < 500 mg / L.

[0039] In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of K + is 620 mg / L or 761 mg / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of Na + is 27 g / L or 64 g / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of S 2- is 14 g / L or 12 g / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of S2O3 2- is 7.3 g / L or 11.4 g / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of SCN - is 160 g / L or 240 g / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of CN - is 2500 mg / L or 3850 mg / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of Fe 2+ is 22 mg / L or 42 mg / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of Mn 2+ is 2 mg / L or 1 mg / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of COD is 4200 mg / L or 4800 mg / L. In certain embodiments, in the coking coal gas desulfurization waste liquid, the content of ammonia nitrogen is 212 mg / L or 320 mg / L.

[0040] In certain embodiments of the present invention, the temperature of the reaction is 20 to 30 °C, and the time is 68 to 76 h. In certain embodiments, the temperature of the reaction is 25 °C or 27 °C. In certain embodiments, the time of the reaction is 72 h or 68 h.

[0041] In the present invention, the coking coal gas desulfurization waste liquid is mixed with sulfur dioxide gas. The sulfur dioxide gas can react with H2S in the desulfurization waste liquid to generate S and H2O; metal impurity ions (such as Fe 2+ , Mn 2+ ) can react with S 2- in the desulfurization waste liquid to generate FeS and MnS; if there is oxygen mixed in the sulfur dioxide gas, then S2O3 2- can react with O2 to generate S and SO4 2- .

[0042] In the present invention, the coking coal gas desulfurization waste liquid is mixed with sulfur dioxide gas, and the pH value is controlled to be 6.0 to 6.2, which is beneficial to the removal of S 2- , and does not damage the solution buffer system.

[0043] In certain embodiments of the present invention, the sulfur dioxide gas may be pure SO2 gas, or SO2 gas generated during the acid-making conversion process, or acid-making tail gas. The acid-making tail gas may be the acid-making tail gas generated after sulfuric acid preparation, containing SO2, SO3, etc.

[0044] In certain embodiments of the present invention, mixing the coking wastewater desulfurization waste liquid with sulfur dioxide gas includes:

[0045] Introducing sulfur dioxide gas into the coking wastewater desulfurization waste liquid; or spraying the acid-making tail gas containing sulfur dioxide gas with the coking wastewater desulfurization waste liquid. The tail gas containing sulfur dioxide gas is the acid-making tail gas.

[0046] In certain embodiments of the present invention, the filtering method is plate-and-frame filtering, and the filtering precision is 0.5 - 1 μm. In certain embodiments of the present invention, the filtering uses the fully automatic square plate-and-frame filter of Jingjin Environmental Protection, with a filtering precision of 0.5 μm and a material of 304 stainless steel. In certain embodiments of the present invention, the filtering uses the fully automatic square plate-and-frame filter of Changjie Filter Equipment, with a filtering precision of 0.5 μm and a material of 304 stainless steel.

[0047] After filtering, a first filtrate and a sulfur-containing precipitate are obtained.

[0048] In certain embodiments of the present invention, the sulfur-containing precipitate can be mixed with acid-making after drying. Specifically, the sulfide is mixed into the pyrite or sulfur raw material to jointly prepare sulfuric acid.

[0049] The first filtrate enters the micro-electrolysis reactor for catalytic oxidation reaction; the micro-electrolysis reactor is filled with iron-carbon active raw materials.

[0050] In certain embodiments of the present invention, the iron-carbon active raw materials include blast furnace waste pig iron blocks and columnar activated carbon; or the iron-carbon active raw materials include ellipsoidal iron-carbon materials. In certain embodiments, the columnar activated carbon is coconut shell activated carbon.

[0051] In certain embodiments of the present invention, the mass content of Fe in the blast furnace waste pig iron blocks is 93% - 94%.

[0052] In certain embodiments of the present invention, the mass content of C in the columnar activated carbon is 4% - 5%.

[0053] In certain embodiments of the present invention, in the iron-carbon active raw materials, the mass ratio of Fe to C is 8.8 - 9.2:1. In certain embodiments, in the iron-carbon active raw materials, the mass ratio of Fe to C is 9.2:1 or 9.0:1.

[0054] In certain embodiments of the present invention, the residence time of the first filtrate in the micro-electrolysis reactor is 20 to 25 minutes. In certain embodiments, the residence time of the first filtrate in the micro-electrolysis reactor is 23 minutes or 25 minutes.

[0055] In certain embodiments of the present invention, the temperature of the catalytic oxidation reaction is 25 to 30 °C. In certain embodiments, the temperature of the catalytic oxidation reaction is 25 °C or 28 °C.

[0056] In certain embodiments of the present invention, the mass ratio of the first filtrate to the iron-carbon active raw material is 80 to 100:1. In certain embodiments, the mass ratio of the first filtrate to the iron-carbon active raw material is 90:1 or 85:1.

[0057] In the present invention, during the catalytic oxidation reaction, most of the Fe generated in the micro-electrolysis process 2+ complexes with CN in the coking gas desulfurization waste liquid - to form a precipitate of Fe2[Fe(CN)6].

[0058] After the catalytic oxidation reaction is completed, the product liquid after the catalytic oxidation reaction is mixed with a hydrogen peroxide solution, and after filtration, Fe4[Fe(CN)6]3 crystals, Fe(OH)3 precipitate, and a second filtrate are obtained.

[0059] In certain embodiments of the present invention, the concentration of the hydrogen peroxide solution is 0.05 to 0.1 g / L.

[0060] In certain embodiments of the present invention, the molar ratio of hydrogen peroxide to Fe in the product liquid 2+ (including Fe in the Fe2[Fe(CN)6] precipitate 2+ and a small amount of Fe in the product liquid 2+ ) is 0.15 to 0.3:1. In certain embodiments, the molar ratio of hydrogen peroxide to Fe in the product liquid 2+ is 0.15:1 or 0.3:1.

[0061] The first filtrate is pumped in from the upper part of the filler (iron-carbon active raw material) of the micro-electrolysis reactor, passes through the iron-carbon active raw material, and then flows out from the upper part of the iron-carbon active raw material, ensuring a full and efficient reaction in the micro-electrolysis reaction system, and breaking the chains of macromolecular organic pollutants such as cyclic ones into small molecules. The Fe generated in the micro-electrolysis process 2+ complexes with CN in the coking gas desulfurization waste liquid - to form a precipitate of Fe2[Fe(CN)6], and then hydrogen peroxide solution is added to oxidize Fe 2+ to Fe 3+, the precipitate is further converted into Fe4[Fe(CN)6]3 crystals, and a small amount of Fe(OH)3 precipitate is generated at the same time.

[0062] Detect the content of SCN - in the second filtrate;

[0063] When the content of SCN - in the second filtrate is less than 180 g / L, adjust the pH value of the second filtrate to 10 - 10.5 with sodium hydroxide solution and reuse it in the coke oven gas desulfurization system;

[0064] When the content of SCN - in the second filtrate is above 180 g / L, mix it with ammonia water solution, and after filtration, obtain solid NH4SCN and treated water body.

[0065] In some embodiments of the present invention, when the content of SCN - in the second filtrate is less than 180 g / L, pump it into the lean liquid tank, and adjust the pH value of the second filtrate to 10 - 10.5 with sodium hydroxide solution. At this time, the buffer system HCO3 - in the solution is converted into CO3 2- , which can fully absorb H2S, HCN, etc. in the coke oven gas. Therefore, it can be reused in the coke oven gas desulfurization system. After absorption, desorption is carried out. After desorption, the lean liquid is then introduced with SO2 gas until the pH value is 6.0, and then left to stand for precipitation.

[0066] In some embodiments of the present invention, the mass concentration of the sodium hydroxide solution is 30%.

[0067] When the content of SCN - in the second filtrate is above 180 g / L, mix it with ammonia water solution, and after filtration, obtain solid NH4SCN and treated water body.

[0068] In some embodiments of the present invention, the ammonia water solution is the ammonia-containing wastewater discharged from the ammonia distillation system.

[0069] In some embodiments of the present invention, the mass concentration of the ammonia water solution is 1% - 3%. In some embodiments, the mass concentration of the ammonia water solution is 3%.

[0070] In some embodiments of the present invention, the NH 4+ in the ammonia water solution and the SCN - in the second filtrate have a molar ratio of 1.0 - 1.2:1. In some embodiments of the present invention, the NH 4+ in the ammonia water solution and the SCN - in the second filtrate have a molar ratio of 1.0:1 or 1.2:1.

[0071] In some embodiments of the present invention, the temperature of the aqueous ammonia solution is 50 to 60 °C. In some embodiments, the temperature of the aqueous ammonia solution is 50 °C or 60 °C.

[0072] In some embodiments of the present invention, the filtration is carried out using a microfilter, the filtration accuracy is 0.1 to 0.2 μm, and the material is 316L stainless steel. In some embodiments, the filtration accuracy is 0.1 μm or 0.2 μm.

[0073] In some embodiments of the present invention, after obtaining the NH4SCN solid, it further includes: washing with water and drying.

[0074] In some embodiments of the present invention, the treated water body can be directly discharged to the regulation tank of the biochemical wastewater treatment system for further treatment.

[0075] The present invention places no special restrictions on the sources of raw materials used above, and they can be commercially available generally.

[0076] The treatment method of coke oven gas desulfurization waste liquid provided by the present invention not only meets the requirement of recycling desulfurization waste liquid, but also recovers pollutants such as CN - , SCN - in the waste liquid, and reduces the treatment load of the biochemical system, having good environmental and social benefits.

[0077] To further illustrate the present invention, the following examples are used to describe in detail a treatment method of coke oven gas desulfurization waste liquid provided by the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0078] The raw materials used in the following examples are all commercially available generally.

[0079] Example 1

[0080] In the coke oven gas desulfurization waste liquid, the content of K + is 620 mg / L, the content of Na + is 27 g / L, the content of S 2- is 14 g / L, the content of S2O3 2- is 7.3 g / L, the content of SCN - is 160 g / L, the content of CN - is 2500 mg / L, the content of Fe 2+ is 22 mg / L, the content of Mn 2+ is 2 mg / L, the content of COD is 4200 mg / L, and the content of ammonia nitrogen is 212 mg / L;

[0081] 1) Sulfur dioxide gas is introduced into the coking wastewater desulfurization waste liquid until the pH value reaches 6.0, and the reaction is carried out at 25 °C for 72 h. The obtained reaction feed liquid is filtered through a fully automatic square plate and frame filter (Jingjin Environmental Protection, with a filtration accuracy of 0.5 μm and a material of 304 stainless steel) to obtain a first filtrate and a sulfur-containing precipitate; the sulfur-containing precipitate can be mixed and burned to produce sulfuric acid after drying;

[0082] 2) The first filtrate enters a micro-electrolysis reactor and undergoes a catalytic oxidation reaction at 25 °C; the micro-electrolysis reactor is filled with iron-carbon active raw materials; the iron-carbon active raw materials include ellipsoidal iron-carbon materials; the mass ratio of the first filtrate to the iron-carbon active raw materials is 90:1, and the mass ratio of Fe to C in the iron-carbon active raw materials is 9.2:1; the residence time of the first filtrate in the micro-electrolysis reactor is 23 min; the first filtrate is pumped into the upper part of the filler (iron-carbon active raw materials) of the micro-electrolysis reactor, passes through the iron-carbon active raw materials, and then flows out from the upper part of the iron-carbon active raw materials; during the catalytic oxidation reaction, most of the Fe generated during the micro-electrolysis process 2+ complexes with CN in the coking wastewater desulfurization waste liquid - to form a precipitate of Fe2[Fe(CN)6];

[0083] 3) After the catalytic oxidation reaction is completed, the product feed liquid after the catalytic oxidation reaction is mixed with a hydrogen peroxide solution (concentration of 0.08 g / L), and after filtration, Fe4[Fe(CN)6]3 crystals, Fe(OH)3 precipitate and a second filtrate are obtained; the molar ratio of hydrogen peroxide to Fe in the product feed liquid 2+ (including the slightly soluble Fe in the Fe2[Fe(CN)6] precipitate 2+ and a small amount of Fe in the product feed liquid 2+ ) is 0.15:1;

[0084] 4) The content of SCN in the second filtrate is detected - ;

[0085] When the content of SCN in the second filtrate - is less than 180 g / L, the pH value of the second filtrate is adjusted to 10 with sodium hydroxide solution and reused in the coking wastewater desulfurization system;

[0086] When the content of SCN in the second filtrate - is above 180 g / L, it is mixed with an ammonia water solution (mass concentration of 3%), and after filtration, NH4SCN solid and treated water body are obtained; the ammonia water solution is the ammonia-containing wastewater discharged from the ammonia distillation system; the NH in the ammonia water solution 4+ and the SCN in the second filtrate - have a molar ratio of 1.0:1; the temperature of the ammonia water solution is 50 °C;

[0087] The filtration is carried out using a microporous filter with a filtration accuracy of 0.2 μm and a material of 316L stainless steel;

[0088] After obtaining the NH4SCN solid, it further includes: washing with water and drying.

[0089] In this embodiment, the yield and purity of the dried NH4SCN solid are detected. The experimental results show that the purity of the NH4SCN solid is 85.2%.

[0090] In this embodiment, the treated water body is detected. The experimental results show that in the treated water body, S 2- has a removal efficiency of 95.7%, CN - has a removal efficiency of 90%, and SCN - has a removal efficiency of 72%.

[0091] In the treated water body, the contents of COD and ammonia nitrogen are 3930 mg / L and 122 mg / L respectively, and it can be discharged to the regulation tank of the biochemical wastewater treatment system for further treatment.

[0092] Example 2

[0093] In the coking gas desulfurization waste liquid, the content of K + is 761 mg / L, the content of Na + is 64 g / L, the content of S 2- is 12 g / L, the content of S2O3 2- is 11.4 g / L, the content of SCN - is 240 g / L, the content of CN - is 3850 mg / L, the content of Fe 2+ is 42 mg / L, the content of Mn 2+ is 1 mg / L, the content of COD is 4800 mg / L, and the content of ammonia nitrogen is 320 mg / L;

[0094] 1) Sulfur dioxide gas is introduced into the coking gas desulfurization waste liquid until the pH value reaches 6.0, and the reaction is carried out at 27 °C for 68 h. The obtained reaction feed liquid is filtered through a full-automatic square plate-frame filter (Changjie filtration equipment, with a filtration accuracy of 0.5 μm and a material of 304 stainless steel) to obtain a first filtrate and a sulfur-containing precipitate; the sulfur-containing precipitate can be mixed with coal for sulfuric acid production after drying;

[0095] 2) The first filtrate enters a micro-electrolysis reactor for catalytic oxidation reaction at 28°C; the micro-electrolysis reactor is filled with iron-carbon active raw materials; the iron-carbon active raw materials include ellipsoidal iron-carbon materials; the mass ratio of the first filtrate to the iron-carbon active raw materials is 85:1, and the mass ratio of Fe to C in the iron-carbon active raw materials is 9.0:1; the residence time of the first filtrate in the micro-electrolysis reactor is 25 min; the first filtrate is pumped into the micro-electrolysis reactor from the upper part of the filler (iron-carbon active raw materials), passes through the iron-carbon active raw materials, and then flows out from the upper part of the iron-carbon active raw materials; during the catalytic oxidation reaction, most of the Fe 2+ complexes with CN - in the coking gas desulfurization waste liquid to form a precipitate of Fe2[Fe(CN)6];

[0096] 3) After the catalytic oxidation reaction is completed, the product liquid after the catalytic oxidation reaction is mixed with a hydrogen peroxide solution (concentration: 0.08 g / L), and after filtration, Fe4[Fe(CN)6]3 crystals, Fe(OH)3 precipitate, and a second filtrate are obtained; the molar ratio of hydrogen peroxide to Fe 2+ (including the slightly soluble Fe 2+ in the Fe2[Fe(CN)6] precipitate and a small amount of Fe 2+ in the product liquid) is 0.3:1;

[0097] 4) Detect the content of SCN - in the second filtrate;

[0098] When the content of SCN - in the second filtrate is less than 180 g / L, the pH value of the second filtrate is adjusted to 10 with sodium hydroxide solution and reused in the coking gas desulfurization system;

[0099] When the content of SCN - in the second filtrate is 180 g / L or more, it is mixed with an ammonia water solution (mass concentration: 3%), and after filtration, NH4SCN solid and treated water body are obtained; the ammonia water solution is the ammonia-containing wastewater discharged from the ammonia distillation system; the molar ratio of NH 4+ in the ammonia water solution to SCN - in the second filtrate is 1.2:1; the temperature of the ammonia water solution is 60°C;

[0100] The filtration is carried out using a microporous filter, the filtration accuracy is 0.1 μm, and the material is 316L stainless steel;

[0101] After obtaining the NH4SCN solid, it also includes: washing and drying.

[0102] In this embodiment, the yield and purity of the dried NH4SCN solid were detected. The experimental results showed that the purity of the NH4SCN solid was 87%.

[0103] In this embodiment, the treated water body was detected. The experimental results showed that in the treated water body, S - had a removal efficiency of 92%, CN - had a removal efficiency of 84.5%, and SCN - had a removal efficiency of 78.3%.

[0104] In the treated water body, the contents of COD and ammonia nitrogen were 3100 mg / L and 145 mg / L respectively, and it could be discharged to the regulation tank of the biochemical wastewater treatment system for further treatment.

[0105] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for treating coking wastewater desulfurization waste liquid, comprising the following steps: A) Mix the coking wastewater desulfurization waste liquid with sulfur dioxide gas until the pH value is 6.0 - 6.2, carry out a reaction, filter the obtained reaction feed liquid to obtain a first filtrate and a sulfur-containing precipitate; In the coke oven gas desulfurization waste liquid, the content of K + is 500 - 900 mg / L, the content of Na + is 25 - 80 g / L, the content of S 2- is 10 - 15 g / L, the content of S2O3 2- is 6 - 15 g / L, the content of SCN - is 140 - 240 g / L, the content of CN - is 500 - 4000 mg / L, the content of Fe 2+ is 20 - 100 mg / L, the content of Mn 2+ is < 10 mg / L, the content of COD is 2000 - 5000 mg / L, and the content of ammonia nitrogen is < 500 mg / L; B) The first filtrate enters a micro-electrolysis reactor for a catalytic oxidation reaction; the micro-electrolysis reactor is filled with an iron-carbon active raw material; C) Mix the product feed liquid after the catalytic oxidation reaction with a hydrogen peroxide solution, and after filtration, obtain Fe4[Fe(CN)6]3 crystals, Fe(OH)3 precipitate and a second filtrate; D) Detect the content of SCN in the second filtrate - ; When the content of SCN - in the second filtrate is less than 180 g / L, the pH value of the second filtrate is adjusted to 10 - 10.5 with sodium hydroxide solution and recycled to the coke oven gas desulfurization system; When the content of SCN - in the second filtrate is above 180 g / L, it is mixed with an ammonia water solution, and after filtration, NH4SCN solid and treated water are obtained.

2. The processing method according to claim 1, characterized in that, In step A), the temperature of the reaction is 20 - 30 °C and the time is 68 - 76 h.

3. The processing method according to claim 1, characterized in that, In step A), the filtration method is plate-and-frame filtration, and the filtration accuracy is 0.5 - 1 μm.

4. The processing method according to claim 1, characterized in that In step B), the iron-carbon active raw material includes blast furnace waste pig iron blocks and columnar activated carbon; or the iron-carbon active raw material includes ellipsoidal iron-carbon materials; The mass content of Fe in the blast furnace waste pig iron blocks is 93% - 94%; The mass content of C in the columnar activated carbon is 4% - 5%; In the iron-carbon active raw material, the mass ratio of Fe to C is 8.8 - 9.2:

1.

5. The processing method according to claim 1, characterized in that, In step B), the residence time of the first filtrate in the micro-electrolysis reactor is 20 - 25 min; The temperature of the catalytic oxidation reaction is 25 - 30 °C.

6. The processing method according to claim 1, characterized in that, In step B), the mass ratio of the first filtrate to the iron-carbon active raw material is 80 - 100:

1.

7. The processing method according to claim 1, characterized in that In step C), the concentration of the hydrogen peroxide solution is 0.05 - 0.1 g / L; The molar ratio of the hydrogen peroxide to Fe in the product liquid material is 2+ 0.15 to 0.3:

1.

8. The processing method according to claim 1, wherein In step D), the ammonia water solution is the ammonia-containing wastewater discharged from the ammonia distillation system; The concentration of the ammonia water solution is 1% - 3%; The NH in the aqueous ammonia solution 4+ and the SCN in the second filtrate - have a molar ratio of 1.0 to 1.2:1; The temperature of the ammonia water solution is 50 - 60 °C.

9. The processing method according to claim 1, characterized in that, In step D), the filtration accuracy is 0.1 - 0.2 μm.