阅读说明：本技术 一种焦炉烟气脱硫副产物脱硫灰的回收方法 (Method for recovering desulphurization ash of coke oven flue gas desulphurization by-product ) 是由 高翔 于 2019-11-05 设计创作，主要内容包括：本发明公开了一种焦炉烟气脱硫副产物脱硫灰的回收方法,属于焦炉烟气治理技术领域。一种焦炉烟气脱硫副产物脱硫灰的回收方法,步骤为：(1)按照质量比为1：6.5-7.5脱硫灰：水混合,搅拌均匀,过滤得清液Ⅰ；(2)对清液Ⅰ进行吸附脱色,过滤得清液Ⅱ；(3)将清液Ⅱ中加入酸性溶液,调PH值至5.5～7.5,然后加入氧化剂,控制溶液中游离氯值为零,获得调节液；(4)采用纳滤膜对调节液液进行分离,分别回收清水侧溶液和浓水侧溶液；(5)将浓水侧溶液处理,得到硫酸钠。本发明可广泛应用于以碱金属盐类为脱硫剂的脱硫灰的处理,工艺简单,成本低廉,易于操作,可实现脱硫灰变废为宝,降低环境压力的目的。(The invention discloses a method for recovering desulfurization ash which is a byproduct of coke oven flue gas desulfurization, and belongs to the technical field of coke oven flue gas treatment. A method for recovering desulfurization ash of a byproduct of coke oven flue gas desulfurization comprises the following steps: (1) according to the mass ratio of 1: 6.5-7.5 desulfurized fly ash: mixing water, stirring uniformly, and filtering to obtain clear liquid I; (2) adsorbing and decoloring the clear liquid I, and filtering to obtain a clear liquid II; (3) adding an acidic solution into the clear liquid II, adjusting the pH value to 5.5-7.5, then adding an oxidant, and controlling the free chlorine value in the solution to be zero to obtain a regulating solution; (4) separating the regulating solution by adopting a nanofiltration membrane, and respectively recovering a clear water side solution and a concentrated water side solution; (5) the concentrated aqueous side solution was treated to obtain sodium sulfate. The method can be widely applied to the treatment of the desulfurization ash which takes alkali metal salts as a desulfurizer, has simple process, low cost and easy operation, and can realize the purposes of changing the desulfurization ash into valuables and reducing the environmental pressure.)

1. A method for recovering desulfurization ash of a byproduct of coke oven flue gas desulfurization is characterized by comprising the following steps:

(1) dissolving and filtering: according to the mass ratio of 1: 6.5-7.5 desulfurized fly ash: mixing water, stirring uniformly, and filtering to obtain clear liquid I;

(2) adsorption: adsorbing and decoloring the clear liquid I, and filtering to obtain a clear liquid II;

(3) adjusting: adding an acidic solution into the clear liquid II, adjusting the pH value to 5.5-7.5, then adding an oxidant, and controlling the free chlorine value in the solution to be zero to obtain a regulating solution;

(4) separation: separating the regulating solution by adopting a nanofiltration membrane, and respectively recovering a clear water side solution and a concentrated water side solution;

(5) recovering sodium sulfate: the concentrated aqueous side solution was treated to obtain sodium sulfate.

2. The method for recovering the desulfurization ash as the byproduct of coke oven flue gas desulfurization according to claim 1, wherein the adsorptive decolorization is performed by using fiber or activated coke.

3. The method for recovering the desulfurization ash as the byproduct of coke oven flue gas desulfurization according to claim 1 or 2, wherein the acidic solution is dilute sulfuric acid or hydrochloric acid.

4. The method for recovering the desulfurization ash produced by the desulfurization of the coke oven flue gas according to claim 1 or 2, wherein the oxidant is sodium hypochlorite.

5. The method for recovering the desulfurization ash as the byproduct of coke oven flue gas desulfurization according to claim 1 or 2, wherein the nanofiltration membrane is used for separating substances in the solution, wherein the clear water side is NaCl solution, and the concentrated water side is Na₂SO₄And (3) solution.

6. The method for recovering the desulfurization ash as the byproduct of coke oven flue gas desulfurization according to claim 1 or 2, wherein a sodium sulfate finished product can be obtained after evaporation treatment of the concentrated aqueous solution.

7. The method for recovering the desulfurization ash as the byproduct of the coke oven flue gas desulfurization according to claim 1 or 2, wherein the concentrated aqueous side solution is subjected to freezing treatment to obtain a finished product of sodium sulfate.

8. The method for recovering the desulfurization ash as the byproduct of coke oven flue gas desulfurization according to claim 7, wherein the concentrated aqueous side solution is subjected to low-temperature freezing treatment at 0-5 ℃.

Technical Field

The invention belongs to the technical field of coke oven flue gas treatment, relates to coke oven flue gas desulfurization, and particularly relates to a method for recovering desulfurization ash which is a byproduct of coke oven flue gas desulfurization.

Background

Along with the increasing severity of haze, the state requires that flue gas generated by coke oven production is treated. The emission standard of pollutants for the coking chemical industry (GB16171-2012) specifies: from 1 month and 1 day of 2015, SO in coal charging and coke pushing flue gas of new and old coke ovens in general areas₂Emission concentration limit of 50mg/Nm³The special limit area is 30mg/Nm³Even less than 15mg/Nm occurs in individual regions³Ultra-low emission requirements. The existing coke oven flue gas desulfurization technology depends on the type and the operation characteristics of a desulfurizing agentGenerally, wet, semi-dry and dry desulfurization can be classified.

Dry and semi-dry desulfurization, which is a desulfurization production process using alkali metal salts as a desulfurizing agent, is widely applied to flue gas desulfurization engineering at present due to the advantages of short process flow, small occupied area, investment saving, simple control, low water consumption, no chimney rain and the like, and the desulfurized ash is a byproduct generated by the semi-dry flue gas desulfurization process and mainly comprises the following components: free calcium oxide, calcium sulfite, calcium carbonate, calcium sulfate, calcium hydroxide and the like.

Because the desulfurized fly ash is unstable, alkalescent and easy to decompose, the comprehensive utilization of the desulfurized fly ash is very difficult. At present, most enterprises adopt a centralized accumulation mode to treat desulfurized fly ash, however, the treatment mode has inherent defects that the accumulated desulfurized fly ash storage cost and the environmental protection treatment are increased along with the continuous production, and meanwhile, the risk of causing environmental pollution is also increased, and the method inevitably becomes a great burden of the enterprises. Because the yield of the byproduct desulfurized fly ash generated by dry and semi-dry desulfurization is high, the requirements for separating and recycling the desulfurized fly ash are urgent.

The invention discloses a method for separating and recovering a byproduct desulfurized ash of coke oven flue gas desulfurization, aiming at solving the problem of byproduct solid waste desulfurized ash generated in dry and semi-dry desulfurization processes.

Disclosure of Invention

The invention aims to provide a method for recovering desulfurization ash which is a byproduct of coke oven flue gas desulfurization.

The invention is realized by the following technical scheme:

a method for recovering desulfurization ash of a byproduct of coke oven flue gas desulfurization comprises the following steps:

(1) dissolving and filtering: according to the mass ratio of 1: 6.5-7.5 desulfurized fly ash: mixing water, stirring uniformly, and filtering to obtain clear liquid I;

(2) adsorption: adsorbing and decoloring the clear liquid I, and filtering to obtain a clear liquid II;

(3) adjusting: adding an acidic solution into the clear liquid II, adjusting the pH value to 5.5-7.5, then adding an oxidant, and controlling the free chlorine value in the solution to be zero to obtain a regulating solution;

(4) separation: separating the regulating solution by adopting a nanofiltration membrane, and respectively recovering a clear water side solution and a concentrated water side solution;

(5) recovering sodium sulfate: the concentrated aqueous side solution was treated to obtain sodium sulfate.

Furthermore, the adsorption decoloration is to use fiber or active coke to carry out adsorption decoloration so as to achieve the purpose of removing colored substances such as carbon black and the like.

The acid solution is dilute sulfuric acid or hydrochloric acid, the pH value is adjusted to 5.5-7.5, and CO3 in the solution is added^2-Is CO₂。

The oxidant is sodium hypochlorite, and the adding amount of NaClO is determined by SO in the actual material₃ ^2-Content determination, NaClO will lower valence ion SO₃ ^2-Conversion to higher valent ions SO₄ ^2-Metering in Na₂SO₃Free chlorine in the hypochlorous acid is reduced, and the value of the free chlorine is controlled to be zero.

The nanofiltration membrane separates substances in the solution, the clear water side is NaCl solution, and the concentrated water side is Na₂SO₄And (3) solution.

After the solution on the concentrated water side is evaporated, a finished product of sodium sulfate can be obtained, and the detection shows that every 1Kg of desulfurized fly ash can obtain 530-580g of sodium sulfate, and the yield is about 85%.

After the concentrated water side solution is subjected to freezing treatment, a finished sodium sulfate product can be obtained, and 600-630g of Na can be obtained by detecting each 1Kg of desulfurized fly ash₂SO₄·10H₂O, the yield is about 95 percent.

And freezing the concentrated water side solution at a low temperature of 0-5 ℃ to obtain a finished sodium sulfate product.

The method is used for treating the solid waste desulfurization ash generated by treating the coke oven flue gas by using alkali metal salts as a desulfurizing agent, wherein the component of the desulfurization ash is NaCO₃Dissolving desulfurized ash in water, and primarily filtering to remove insoluble substances such as dust particles and the like; then adsorbing and decoloring by using fibers or active coke to remove colored substances such as carbon black and the like; then adjusted using a reagent to whichConversion of CO by hydrochloric or sulfuric acid₃ ^2-Is CO₂Adding sodium hypochlorite NaClO serving as an oxidant, and adding low-valence ions SO₃ ^2-Conversion to higher valent ions SO₄ ^2-Reducing the components of the solution without introducing new components, freezing or evaporating to separate out sodium sulfate, and centrifuging to obtain Na₂SO₄·10H₂And (4) O, finishing.

The method can be widely applied to the treatment of the desulfurization ash which takes alkali metal salts as a desulfurizer, has simple process, low cost and easy operation, and can realize the purposes of changing the desulfurization ash into valuables and reducing the environmental pressure.

Detailed Description

The present invention is further described below with reference to specific examples, but it should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. Various changes or modifications of the present invention based on the present invention should be made by those skilled in the art within the scope of the present invention.