阅读说明：本技术 一种资源化利用半干法脱硫灰制备含硫化工产品的方法 (Method for preparing sulfur-containing chemical products by resource utilization of semi-dry desulfurization ash ) 是由 甘敏 刘林程 刘琪英 范晓慧 严泽凡 季志云 孙增青 陈许玲 黄晓贤 袁礼顺 于 2021-07-14 设计创作，主要内容包括：本发明公开了一种资源化利用半干法脱硫灰制备含硫化工产品的方法,该方法是将半干法脱硫灰与钾长石混合均匀后进行低温焙烧,得到二氧化硫气体和混合固体；将混合固体进行高温焙烧,得到含硫酸钾的固体；将含硫酸钾的固体通过湿法浸出,得到浸出液和浸出渣；浸出液通过蒸发结晶得到硫酸钾产品,浸出渣作为建筑材料或耐火材料原料。该方法实现了半干法脱硫灰的全组分资源化利用,可以获得硫酸以及高附加值的硫酸钾产品,且浸出渣可作为建筑材料或耐火材料的原料,且无有害的气体、固体和液体产生,实现半干法脱硫灰的大宗化、无害化、高质化利用。(The invention discloses a method for preparing a sulfur-containing chemical product by resource utilization of semi-dry desulfurized fly ash, which comprises the steps of uniformly mixing the semi-dry desulfurized fly ash and potassium feldspar, and then roasting at a low temperature to obtain sulfur dioxide gas and mixed solids; roasting the mixed solid at high temperature to obtain a solid containing potassium sulfate; leaching a solid containing potassium sulfate by a wet method to obtain a leaching solution and leaching residues; and (3) evaporating and crystallizing the leaching solution to obtain a potassium sulfate product, wherein leaching residues are used as building materials or refractory materials. The method realizes the full component resource utilization of the semi-dry desulfurized fly ash, can obtain sulfuric acid and potassium sulfate products with high added values, can use the leached slag as a raw material of building materials or refractory materials, does not generate harmful gas, solid and liquid, and realizes the large-scale, harmless and high-quality utilization of the semi-dry desulfurized fly ash.)

1. A method for preparing a sulfur-containing chemical product by resource utilization of semi-dry desulfurization ash is characterized by comprising the following steps: the method comprises the following steps:

1) uniformly mixing the semidry desulfurization ash and potassium feldspar, and then roasting at low temperature to obtain sulfur dioxide gas and mixed solids;

2) roasting the mixed solid at high temperature to obtain a solid containing potassium sulfate;

3) leaching the solid containing potassium sulfate by a wet method to obtain a leaching solution and leaching residues; and evaporating and crystallizing the leaching solution to obtain a potassium sulfate product, wherein the leaching slag is used as a building material or refractory material raw material.

2. The method for preparing the sulfur-containing chemical product by resource utilization of the semidry desulfurization ash according to claim 1, characterized in that: the semi-dry desulfurized fly ash is a byproduct of semi-dry desulfurization of flue gas of a steel plant or a power plant.

3. The method for preparing the sulfur-containing chemical product by resource utilization of the semidry desulfurization ash according to claim 1, characterized in that: the mass ratio of the semi-dry desulfurization ash to the potassium feldspar is 1-4: 1.

4. The method for preparing the sulfur-containing chemical products by resource utilization of the semidry desulfurization ash according to claim 1 or 3, wherein the method comprises the following steps: the potassium feldspar contains 8-15% of potassium oxide by mass percent.

5. The method for preparing the sulfur-containing chemical product by resource utilization of the semidry desulfurization ash according to claim 1, characterized in that: the low-temperature roasting conditions are as follows: the roasting temperature is 900-950 ℃, and the roasting time is 0.5-4 h.

6. The method for preparing the sulfur-containing chemical product by resource utilization of the semidry desulfurization ash according to claim 1, characterized in that: the sulfur dioxide gas is used for preparing acid.

7. The method for preparing the sulfur-containing chemical product by resource utilization of the semidry desulfurization ash according to claim 1, characterized in that: the high-temperature roasting conditions are as follows: the roasting temperature is 1000-1300 ℃, and the roasting time is 0.5-4 h.

8. The method for preparing the sulfur-containing chemical products by resource utilization of the semidry desulfurization ash according to claim 1 or 7, wherein the method comprises the following steps: and circulating the flue gas generated by the high-temperature roasting to the low-temperature roasting.

9. The method for preparing the sulfur-containing chemical product by resource utilization of the semidry desulfurization ash according to claim 1, characterized in that: the wet leaching is carried out by two-stage countercurrent leaching; the first-stage countercurrent leaching adopts leachate obtained by second-stage countercurrent to leach solids containing potassium sulfate, the leachate obtained by the first-stage countercurrent leaching is evaporated and crystallized to obtain a potassium sulfate product, and leaching residues obtained by the first-stage countercurrent leaching adopts water to carry out second-stage countercurrent leaching; and returning the leachate obtained by the second-stage countercurrent leaching to the first-stage countercurrent leaching, and taking the leaching slag obtained by the second-stage countercurrent leaching as a building material or a refractory material raw material.

10. The method for preparing sulfur-containing chemical products by resource utilization of semi-dry desulfurized ash according to claim 9, characterized by comprising the following steps:

the conditions of the first-stage countercurrent leaching are as follows: the temperature is 20-40 ℃, the solid-liquid mass ratio is 1: 3-6, and the time is 10-30 min;

the conditions of the second-stage countercurrent leaching are as follows: the temperature is 20-40 ℃, the solid-liquid mass ratio is 1: 3-6, and the time is 40-60 min.

Technical Field

The invention relates to a method for treating semidry desulfurized fly ash, in particular to a method for preparing sulfur-containing chemical products such as sulfuric acid, potassium sulfate and the like by recycling semidry desulfurized fly ash, belonging to the technical field of solid waste treatment.

Background

The semi-dry desulfurization process has the advantages of high desulfurization efficiency, short process flow, low investment, small occupied area and the like, and is widely applied to the industries of ferrous metallurgy, thermal power generation and the like. At present, projects adopting semi-dry desulphurization are increased day by day, the production amount of semi-dry desulphurization ash is increased year by year, and the semi-dry desulphurization ash produced in China is more than 1000 million tons every year. If waste residues such as industrial byproduct gypsum and the like cannot be comprehensively utilized according to the environmental protection tax Law specified in the environmental protection tax Law executed from 1 month and 1 day in 2018, the environmental protection tax is collected according to 25 yuan/ton. If the semi-dry desulfurized fly ash cannot be reasonably treated, enterprises pay a high additional cost.

The semi-dry desulfurization ash comprises the following main components: free calcium oxide, calcium sulfite, calcium hydroxide, calcium sulfate, a small amount of calcium carbonate and the like. The component characteristics of the semidry desulfurization ash greatly limit the utilization of the semidry desulfurization ash in the traditional fields of building materials, agriculture and the like. State Standard Regulation, SO in ordinary cement₃The content of the calcium sulfate is less than 3.5 percent, while the sulfur content in the semi-dry desulfurization ash is higher, the semi-dry desulfurization ash contains more free calcium oxide, and Ca (OH) is continuously generated in the long-term hydration process₂The volume is expanded continuously, which affects the stability of use, so the semi-dry desulfurized fly ash can not be directly used as cement or the use amount is less, which limits the resource utilization. All in oneIn the process, the hydration reaction of calcium sulfite is slow and is easy to decompose under heat, and if the calcium sulfite is not properly treated, a large amount of SO is generated₂Causing secondary pollution to the environment.

Therefore, only a small part of semi-dry desulfurized fly ash is primarily utilized at present, and the vast majority of desulfurized fly ash is treated in a stacking and burying manner, so that the environment is damaged and land resources are occupied. Meanwhile, a large amount of resources such as calcium, sulfur and the like in the semidry desulfurization ash are not utilized massively, so that the waste of resources is caused. Therefore, the development of the resource utilization technology of the semi-dry desulfurization ash has great significance.

At present, the research at home and abroad mainly comprises oxidizing calcium sulfite in semi-dry desulfurization ash into calcium sulfate by a high-temperature oxidation method, a low-temperature catalysis method, an electrochemical oxidation method and the like, so that the semi-dry desulfurization ash is converted into desulfurization gypsum. The methods have high oxidation cost and low product economy, do not have proper oxidation process equipment, and are not suitable for industrial production. In the process of recycling the desulfurized gypsum, the content of CaO and calcium carbonate in the semi-dry desulfurized fly ash is high, so that the CaSO of the semi-dry desulfurized fly ash is high₄Is much lower than that of wet desulfurization, and its subsequent utilization remains difficult. Therefore, the search for a utilization technology of semidry desulfurized fly ash, which is efficient, low in consumption, economical and feasible, is particularly urgent.

At present, China consumes a great amount of potash fertilizer, the consumption of the potash fertilizer exceeds 40% of the world consumption, and at present, over 40% of potash fertilizer is imported from abroad, so that the price of the potash fertilizer is high. With the continuous improvement of the requirement of the land output capacity, how to reduce the production cost of the potash fertilizer is more and more important to the agricultural development of China.

Disclosure of Invention

The invention aims to provide a method for preparing sulfuric acid, potassium sulfate and other sulfur-containing chemical products by using semi-dry desulfurized ash as a main raw material to realize resource utilization of the semi-dry desulfurized ash, and the method utilizes the semi-dry desulfurized ash as the main raw material and adds potassium feldspar as a potassium source to obtain sulfur dioxide for preparing sulfuric acid and obtain a potassium sulfate product with high added value for preparing a potassium fertilizer through high-temperature calcination, so that the high-efficiency resource utilization of the desulfurized ash is realized, and the leached residues can be used as raw materials of building materials or refractory materials, so that harmful gas, solid and liquid are not generated, and the large-scale, harmless and high-quality utilization of the semi-dry desulfurized ash is realized.

In order to realize the technical purpose, the invention provides a method for preparing a sulfur-containing chemical product by resource utilization of semi-dry desulfurized fly ash, which comprises the following steps:

1) uniformly mixing the semidry desulfurization ash and potassium feldspar, and then roasting at low temperature to obtain sulfur dioxide gas and mixed solids;

2) roasting the mixed solid at high temperature to obtain a solid containing potassium sulfate;

3) leaching the solid containing potassium sulfate by a wet method to obtain a leaching solution and leaching residues; and evaporating and crystallizing the leaching solution to obtain a potassium sulfate product, wherein the leaching slag is used as a building material or refractory material raw material.

The invention takes semidry desulfurization ash and potash feldspar as raw materials, the semidry desulfurization ash is decomposed at low temperature, calcium sulfite in the semidry desulfurization ash is mainly decomposed at low temperature, and SO is recovered in the form of sulfur dioxide₂The gas is used for preparing acid, and simultaneously high-activity calcium oxide components are obtained, the low-temperature roasting solid-phase product and the potassium feldspar are subjected to high-temperature roasting, the high-temperature solid-phase reaction is carried out on the active components such as calcium sulfate, calcium oxide and the like in the low-temperature roasting solid-phase product and the potassium feldspar, the potassium ions in the potassium feldspar can be converted into potassium sulfate components which are easy to leach out by water by utilizing the calcium sulfate, the calcium oxide, the silicon-aluminum components and the like, and the potassium sulfate components can be converted into stable slag phases which can be used as refractory materials or building materials, and the main chemical reactions involved in the two-stage roasting processes of the low-temperature roasting and the high-temperature roasting are as follows:

low-temperature roasting in the first stage:

CaSO₃(s)＝CaO(s)+SO₂(g)；

and (3) second-stage high-temperature roasting:

2KAlSi₃O₈+CaSO₄+6CaO＝Ca₂Al₂SiO₇+K₂SO₄+5CaSiO₃；

2KAlSi₃O₈+CaSO₄+11CaO＝Ca₂Al₂SiO₇+K₂SO₄+5Ca₂SiO₄。

as a preferable scheme, the semidry desulfurized ash is a byproduct of semidry desulfurization of flue gas of a steel plant or a power plant. The semi-dry desulfurization ash is common solid waste in the industry, and mainly comprises calcium sulfite, calcium oxide and calcium hydroxide, and also comprises a small amount of calcium sulfate, calcium carbonate and the like.

Preferably, the mass ratio of the semi-dry desulfurization ash to the potassium feldspar is 1-4: 1.

Preferably, the potassium feldspar contains 8 to 15 mass percent of potassium oxide.

As a preferred scheme, the low-temperature roasting conditions are as follows: the roasting temperature is 900-950 ℃, and the roasting time is 0.5-4 h. Under the optimized low-temperature roasting condition to realize the high-efficiency decomposition of the calcium sulfite in the semi-dry desulfurization ash.

As a preferred embodiment, the sulfur dioxide gas is used for acid production.

As a preferred scheme, the high-temperature roasting conditions are as follows: the roasting temperature is 1000-1300 ℃, and the roasting time is 0.5-4 h. Under the optimized high-temperature roasting condition, the solid-phase reaction of potassium feldspar and a low-temperature roasting product containing calcium oxide, calcium sulfate and other components is mainly realized, the crystal structure of the potassium feldspar is destroyed by utilizing active components such as calcium oxide, and the potassium in the potassium feldspar is converted into water-soluble potassium sulfate, and the slag phase is high-stability potassium aluminosilicate, calcium silicate and the like.

As a preferable scheme, flue gas generated by high-temperature roasting is recycled to low-temperature roasting. The heat in the high-temperature roasting process can be recovered through flue gas circulation, the energy consumption loss is reduced, and meanwhile, the sulfur dioxide component in the flue gas is recovered, and the emission is reduced.

As a preferred scheme, the wet leaching is performed by two-stage countercurrent leaching; the first-stage countercurrent leaching adopts leachate obtained by second-stage countercurrent to leach solids containing potassium sulfate, the leachate obtained by the first-stage countercurrent leaching is evaporated and crystallized to obtain a potassium sulfate product, and leaching residues obtained by the first-stage countercurrent leaching adopts water to carry out second-stage countercurrent leaching; and returning the leachate obtained by the second-stage countercurrent leaching to the first-stage countercurrent leaching, and taking the leaching slag obtained by the second-stage countercurrent leaching as a building material or a refractory material raw material. By adopting two-stage countercurrent leaching, the higher leaching rate of potassium sulfate can be ensured, and the leaching rate is more than 90 percent.

As a preferred scheme, the conditions of the first stage countercurrent leaching are as follows: the temperature is 20-40 ℃, the solid-liquid mass ratio is 1: 3-6, and the time is 10-30 min.

As a preferred scheme, the conditions of the two-stage countercurrent leaching are as follows: the temperature is 20-40 ℃, the solid-liquid mass ratio is 1: 3-6, and the time is 40-60 min.

Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:

the invention uses semidry desulfurization ash and potash feldspar as main raw materials to prepare sulfur-containing chemical products. The method decomposes calcium sulfite to generate SO in the first stage of roasting by a two-stage roasting mode₂And high-activity calcium oxide, which solves the problem that the semi-dry desulfurization ash is difficult to utilize due to unstable property of calcium sulfite; in the second stage of roasting, potassium feldspar reacts with calcium sulfate and calcium oxide to produce potassium sulfate. The method can fully recover sulfur and calcium resources in the semi-dry desulfurization ash to obtain SO₂And potassium sulfate with high added value to obtain SO₂Can be used for preparing industrial sulfuric acid, and the potassium sulfate can be used as a chemical raw material for producing a potash fertilizer, thereby realizing multi-aspect recycling of resources.

At present, the semi-dry desulfurized fly ash is mainly utilized to oxidize calcium sulfite in the desulfurized fly ash into calcium sulfate, namely, the semi-dry desulfurized fly ash is converted into desulfurized gypsum and then is further treated. Regarding the current situation of utilization of semidry desulfurized fly ash, the method has the advantages of short flow, simple operation, large utilization amount, high resource utilization rate, high added-value product generation, high economic benefit and easy realization of industrial application.

The traditional potassium sulfate preparation method mainly comprises a Mannheim production method, a mirabilite production method and the like. The Mannheim production method has the advantages of high product quality, simple production flow, high investment and corrosion and damage of production equipment by generated hydrochloric acid. The mirabilite production method has high conversion rate and small damage degree to equipment, but the process is too complex and is not beneficial to industrial application. Compared with the traditional potassium sulfate preparation method, the method has the advantages of simple flow, high efficiency, green and environment-friendly whole process, no pollutant emission, strong treatment capacity and easy popularization in industrial application.

In conclusion, the method realizes the full resource utilization of the semi-dry process desulfurized fly ash and the clean and efficient treatment of the semi-dry process desulfurized fly ash.

Drawings

FIG. 1 is a process flow diagram for preparing sulfur-containing chemical products from semi-dry desulfurized fly ash.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by those skilled in the art without any creative work based on the embodiments of the present invention belong to the protection scope of the present invention.

Example 1

Adding K into semi-dry desulfurized ash of a certain steel plant₂Potassium feldspar with 8.6% of O content, wherein the ratio of potassium feldspar: the mass ratio of the desulfurized fly ash is 1: mixing the raw materials in proportion 4, performing primary roasting at 900 ℃, wherein the roasting time is 4h, roasting flue gas is used for producing industrial sulfuric acid by an acid making process, performing secondary roasting on the primary roasted product at 1000 ℃, wherein the roasting time is 2h, the second-stage roasting flue gas is circulated to the first-stage roasting, performing two-stage countercurrent leaching on the secondary roasted product, the first-stage leaching temperature is 20 ℃, and the solid-liquid mass ratio is 1:3, the leaching time is 10 min. The second-stage leaching temperature is 20 ℃, and the solid-liquid mass ratio is 1:3, the leaching time is 40 min. The leaching rate of the potassium sulfate of the obtained product is 92 percent, and the main component of leaching residue is Ca₂Al₂SiO₇、Ca₂SiO₄And CaSiO₃As a fire-resistant material or a building material.

Example 2

Adding K into semi-dry desulfurized ash of a certain steel plant₂Potassium feldspar with 10.6% of O content, wherein the ratio of potassium feldspar: the mass ratio of the desulfurized fly ash is 1:3, mixing in proportion, performing primary roasting at 925 ℃, wherein the roasting time is 4h, roasting flue gas is used for producing industrial sulfuric acid by an acid making process, performing secondary roasting on the primary roasted product at 1100 ℃, the roasting time is 1h, circulating the second-stage roasting flue gas to the first-stage roasting, performing two-stage countercurrent leaching on the secondary roasted product, wherein the primary leaching temperature is 30 ℃, and the solid-liquid mass ratio is 1: 6, the leaching time is 20 min. The second-stage leaching temperature is 30 ℃, and the solid-liquid mass ratio is 1: 6, the leaching time is 50 min. The leaching rate of the obtained product potassium sulfate is 94 percent, and the main component of leaching residue is Ca₂Al₂SiO₇、Ca₂SiO₄And CaSiO₃As a fire-resistant material or a building material.

Example 3

Adding K into semi-dry desulfurized ash of a certain steel plant₂Potassium feldspar with 13.4% of O content, wherein the ratio of potassium feldspar: the mass ratio of the desulfurized fly ash is 1: 1, mixing in proportion, performing primary roasting at 950 ℃, wherein the roasting time is 0.5h, roasting flue gas is used for producing industrial sulfuric acid by an acid making process, performing secondary roasting on a primary roasted product at 1200 ℃, wherein the roasting time is 0.5h, the second-stage roasting flue gas is circulated to the first-stage roasting, performing two-stage countercurrent leaching on the secondary roasted product, the primary leaching temperature is 40 ℃, and the solid-liquid mass ratio is 1: 6, the leaching time is 30 min. The second-stage leaching temperature is 40 ℃, and the solid-liquid mass ratio is 1: 6, the leaching time is 60 min. The leaching rate of the obtained product potassium sulfate is 95 percent, and the main component of leaching residue is Ca₂Al₂SiO₇、Ca₂SiO₄And CaSiO₃As a fire-resistant material or a building material.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-described embodiments. Modifications and variations that may occur to those skilled in the art without departing from the spirit and scope of the invention are to be considered as within the scope of the invention.