阅读说明：本技术 一种脱硫灰还原-氧化两段处理的方法 (Reduction-oxidation two-stage treatment method for desulfurized fly ash ) 是由 毛瑞 茅沈栋 王飞 苏航 于 2019-10-23 设计创作，主要内容包括：本发明提供一种脱硫灰还原-氧化两段处理的方法,本方法先将脱硫灰送入一段高温反应器,控制适宜的温度、气氛,将脱硫灰中的亚硫酸钙和硫酸钙还原为硫化钙,再进入二段高温反应器,控制适宜的温度、气氛,使硫化钙转变为二氧化硫和氧化钙,产生含硫烟气和残渣。本发明将脱硫灰转变为富SO<Sub>2</Sub>的烟气和含钙、铁的残渣,富SO<Sub>2</Sub>的烟气可通过除尘、净化、催化氧化、吸收工艺制备硫酸,残渣可按一定比例配入铁矿烧结替代部分含铁原料和熔剂或用于炼钢脱硫,使脱硫灰得到充分的资源化利用,经济效益和环境效益显著。(The invention provides a method for two-stage treatment of reduction-oxidation of desulfurized fly ash, which comprises the steps of firstly feeding desulfurized fly ash into a first-stage high-temperature reactor, controlling proper temperature and atmosphere, reducing calcium sulfite and calcium sulfate in desulfurized fly ash into calcium sulfide, and then feeding into a second-stage high-temperature reactorAnd the reactor is controlled to have proper temperature and atmosphere, so that the calcium sulfide is converted into sulfur dioxide and calcium oxide to generate sulfur-containing flue gas and residues. The invention converts the desulfurized fly ash into rich SO 2 The flue gas and the residue containing calcium and iron are rich in SO 2 The flue gas can be used for preparing sulfuric acid by dedusting, purifying, catalytic oxidation and absorption processes, and the residues can be mixed with iron ore according to a certain proportion to be sintered to replace part of iron-containing raw materials and flux or be used for steel-making desulphurization, so that the desulphurization ash is fully recycled, and the economic benefit and the environmental benefit are obvious.)

1. A method for reducing-oxidizing two-stage treatment of desulfurized fly ash is characterized by comprising the following steps:

(1) sending the pretreated desulfurization ash into a first-stage high-temperature reactor, introducing a reducing atmosphere, wherein the reducing atmosphere comprises carbon monoxide, oxygen and inert gas, the volume fraction of the carbon monoxide is 5-15%, the volume fraction of the oxygen is less than 2%, and the pretreated desulfurization ash is subjected to a reduction reaction in the first-stage high-temperature reactor at a temperature of 800-1000 ℃ until calcium sulfite and calcium sulfate in the desulfurization ash are reduced into calcium sulfide;

(2) feeding the reduced desulfurized ash into a second-stage high-temperature reactor, introducing an oxidizing atmosphere, wherein the oxidizing atmosphere comprises carbon monoxide, oxygen and inert gas, the volume fraction of the oxygen is 5-10%, the volume fraction of the carbon monoxide is less than 1%, and performing oxidation reaction on the reduced desulfurized ash in the second-stage high-temperature reactor at the temperature of 1000-1200 ℃ until calcium sulfide in the desulfurized ash is converted into sulfur dioxide and calcium oxide;

(3) and (3) after the reaction in the step (2) is finished, gas-solid separation is carried out, and then smoke and solid residues are collected.

2. The method of claim 1, wherein the two-stage reduction-oxidation treatment of desulfurized fly ash comprises: the pretreated desulfurization ash is obtained by grinding dry desulfurization ash.

3. The method of claim 1, wherein the two-stage reduction-oxidation treatment of desulfurized fly ash comprises: the pretreated desulfurization ash is obtained by drying, crushing and grinding wet desulfurization ash.

4. The method of claim 1, wherein the two-stage reduction-oxidation treatment of desulfurized fly ash comprises: the inert gas in the reducing atmosphere in the step (1) is nitrogen, carbon dioxide or a mixed gas of the nitrogen and the carbon dioxide.

5. The method of claim 1, wherein the two-stage reduction-oxidation treatment of desulfurized fly ash comprises: and (3) the inert gas in the oxidizing atmosphere in the step (2) is nitrogen, carbon dioxide or a mixed gas of the nitrogen and the carbon dioxide.

Technical Field

The invention belongs to the field of comprehensive utilization of metallurgical solid waste resources, and relates to a desulfurization ash reduction-oxidation two-stage treatment method.

Background

The semi-dry desulfurization process has the advantages of high desulfurization efficiency, short process flow, small occupied area, investment saving and the like, and is widely applied to flue gas desulfurization engineering of small and medium-sized generating sets and sintering plants of part of steel enterprises in China. The raw material of the semi-dry desulfurization process adopts quicklime to prepare slurry, and the slurry is fully contacted and reacted with sulfur-containing flue gas in an absorption tower to achieve the aim of removing SO2 in the flue gas. The major disadvantage of the semi-dry desulfurization process is that a large amount of byproducts, called desulfurization ash, are generated after the flue gas is desulfurized, and belong to metallurgical solid wastes. The main components of the desulfurized fly ash are as follows: free calcium oxide, calcium sulfite, calcium carbonate, calcium sulfate, calcium hydroxide, ferric trioxide, and the like. Because the desulfurized fly ash has the characteristics of unstable components, alkalinity, easy decomposition, easy water absorption, easy expansion and the like, the comprehensive utilization of the desulfurized fly ash is very difficult, and the common treatment mode of the desulfurized fly ash at present is stacking and landfill, thereby not only polluting the environment and occupying the land, but also having great potential safety hazard.

In recent years, many researches on the utilization of desulfurized fly ash resources are carried out, but the desulfurized fly ash resources are not mature in practical application and have many problems, such as the use of desulfurized fly ash in sintering ore blending affects the operation stability rate of a sintering machine and deteriorates the quality of sintered ore; the desulfurized ash is used for preparing various brick products and concrete, and can generate volume expansion to cause cracking; the desulfurized fly ash is used for soil remediation, and causes the problems of secondary pollution and the like, so that the development of a high-efficiency, harmless, stable and feasible resource utilization technology of the desulfurized fly ash has great significance.

Disclosure of Invention

The technical problem to be solved is as follows: aiming at the technical problem that the comprehensive treatment of the desulfurized fly ash is difficult, the invention provides a method for reducing-oxidizing two-stage treatment of the desulfurized fly ash, and the method is used for solving the problem of the comprehensive treatment of the desulfurized fly ash.

The technical scheme is as follows: the invention provides a method for reduction-oxidation two-stage treatment of desulfurized fly ash, which comprises the following steps:

(1) sending the pretreated desulfurization ash into a first-stage high-temperature reactor, introducing a reducing atmosphere, wherein the reducing atmosphere comprises carbon monoxide, oxygen and inert gas, the volume fraction of the carbon monoxide is 5-15%, the volume fraction of the oxygen is less than 2%, and the pretreated desulfurization ash is subjected to a reduction reaction in the first-stage high-temperature reactor at a temperature of 800-1000 ℃ until calcium sulfite and calcium sulfate in the desulfurization ash are reduced into calcium sulfide;

(2) feeding the reduced desulfurized ash into a second-stage high-temperature reactor, introducing an oxidizing atmosphere, wherein the oxidizing atmosphere comprises carbon monoxide, oxygen and inert gas, the volume fraction of the oxygen is 5-10%, the volume fraction of the carbon monoxide is less than 1%, and performing oxidation reaction on the reduced desulfurized ash in the second-stage high-temperature reactor at the temperature of 1000-1200 ℃ until calcium sulfide in the desulfurized ash is converted into sulfur dioxide and calcium oxide;

(3) and (3) after the reaction in the step (2) is finished, gas-solid separation is carried out, and then smoke and solid residues are collected.

Further, the pretreated desulfurization ash is obtained by grinding dry desulfurization ash.

Further, the pretreated desulfurization ash is obtained by drying, crushing and grinding wet desulfurization ash.

Further, the inert gas in the reducing atmosphere in the step (1) is nitrogen, carbon dioxide or a mixed gas of the nitrogen and the carbon dioxide.

Further, the inert gas in the oxidizing atmosphere in the step (2) is nitrogen, carbon dioxide or a mixed gas of the nitrogen and the carbon dioxide.

Has the advantages that: the invention is characterized in that the desulfurized fly ash is converted into rich SO by a reduction-oxidation two-stage treatment process₂The flue gas and the residue containing calcium and iron are rich in SO₂The flue gas is used for preparing sulfuric acid through processes of dust removal, purification, catalytic oxidation and absorption, and residues can be mixed with iron ore according to a certain proportion to be sintered to replace part of iron-containing raw materials and flux or be used for steel-making desulfurization, so that desulfurized ash is fully recycled, and the economic benefit and the environmental benefit are obvious.

Drawings

FIG. 1 is a process flow diagram of a method of the present invention for reduction-oxidation two-stage treatment of desulfurized fly ash.

Detailed Description