阅读说明：本技术 一种硫酸厂动力波稀酸的回收处理方法 (Recovery processing method of dynamic wave dilute acid in sulfuric acid plant ) 是由 曾小林 王国锋 卢慧军 鞠浩 朱先念 于 2020-12-17 设计创作，主要内容包括：本发明公开了一种硫酸厂动力波稀酸的回收处理方法,属于硫酸生产副产动力波稀酸的回收利用技术领域,包括如下步骤：(1)取车间动力波稀酸,采用膜过滤去除动力波稀酸中的杂质,除杂后动力波稀酸中的铁含量低于500ppm；(2)过滤除杂后的稀酸质量百分数提浓至10％以上；(3)提浓后的稀酸用于钛白粉生产过程中的偏钛酸漂白。本发明通过浓缩和膜过滤后,酸浓能达到16％,Fe含量0.02％以下,用以漂白偏钛酸,漂后料浆经二洗后Fe含量在30ppm内,煅烧后的窑下物亮度≥93.8,其他杂质含量也在正常水平,对产品质量无影响,因此本发明提供的技术方案能有效利用动力波稀酸,并减少98％硫酸的使用量,达到副废回收利用、节能减排的目的。(The invention discloses a recovery processing method of dynamic wave dilute acid in a sulfuric acid plant, belonging to the technical field of recovery and utilization of by-product dynamic wave dilute acid in sulfuric acid production, comprising the following steps: (1) taking the power wave dilute acid between the vehicles, removing impurities in the power wave dilute acid by adopting membrane filtration, wherein the iron content in the power wave dilute acid after impurity removal is lower than 500 ppm; (2) concentrating the filtered and impurity-removed dilute acid to over 10 percent by mass; (3) the concentrated dilute acid is used for bleaching metatitanic acid in the production process of titanium dioxide. After concentration and membrane filtration, the acid concentration can reach 16 percent, the Fe content is below 0.02 percent, the bleaching is used for bleaching metatitanic acid, the Fe content of the bleached slurry is within 30ppm after the slurry is subjected to secondary washing, the brightness of calcined kiln waste is more than or equal to 93.8, the content of other impurities is also at a normal level, and the product quality is not influenced, so the technical scheme provided by the invention can effectively utilize dynamic wave dilute acid, reduce the use amount of 98 percent sulfuric acid, and achieve the purposes of recycling side waste, saving energy and reducing emission.)

1. A recovery processing method of power ripples acid of a sulfuric acid plant is characterized by comprising the following steps:

(1) taking the power wave dilute acid between the vehicles, removing impurities in the power wave dilute acid by adopting membrane filtration, wherein the iron content in the power wave dilute acid after impurity removal is lower than 500 ppm;

(2) the diluted acid after impurity removal is used for bleaching metatitanic acid in the production process of titanium dioxide.

2. The method for recovering and treating the dynamic wave dilute acid of the sulfuric acid plant as claimed in claim 1, wherein in the step (1), the membrane used for membrane filtration is an inorganic ceramic membrane.

3. The method for recovering dilute acid according to claim 1, wherein in the step (2), the dilute acid is H₂SO₄:TiO₂Adding a bleaching process according to the mass ratio of 1: 5-1: 8.

4. The method for recovering and treating the dynamic wave dilute acid in the sulfuric acid plant as claimed in claim 3, wherein in the step (2), the iron content in the metatitanic acid before bleaching is 2000-3000 ppm.

5. The method for recovering and treating the dynamic wave dilute acid of the sulfuric acid plant as claimed in claim 4, wherein in the step (2), the content of the trivalent titanium is 0.3-0.8 g/L.

6. The method for recovering and treating dynamic wave dilute acid in a sulfuric acid plant as claimed in claim 5, wherein in the step (2), the bleaching and curing are carried out for 90 minutes, and then washing is carried out, wherein the washing water consumption is not less than 20 times of the total titanium content.

Technical Field

The invention belongs to the technical field of recycling of by-product dynamic wave dilute acid in sulfuric acid production, and particularly relates to a recycling method of dynamic wave dilute acid in a sulfuric acid plant.

Background

At present, a small part of 98% sulfuric acid used in the production process of titanium dioxide of a company is produced by the company, and when 98% acid is produced, flue gas can be generated in the combustion process of raw materials such as sulfur and the like, and the flue gas is generally purified by spraying water. The flue gas contains a small amount of SO₃SO after being sprayed with water₃Will dissolve in water to form dilute sulfuric acid, which is known as kinetic wave dilute acid. Because the spray water is recycled, the concentration of the final dilute sulfuric acid can reach 10-20%. However, the raw material sulfur is often impure and contains impurities, and the sulfur enters dilute sulfuric acid along with flue gas after combustion, so that the acid cannot be directly used for industrial production and can only be sent to a sewage station for treatment. The sulfuric acid consumption is in the forefront of the world every year in China, and the amount of dilute acid generated by producing the sulfuric acid is also large. The method not only brings great pressure to the environmental protection aspect, but also can cause great waste of resources, recycles the dynamic wave dilute acid, produces products with higher added value, and has important influence on the sustainable development of China.

Disclosure of Invention

The invention aims to provide a recovery treatment method of dynamic wave dilute acid in a sulfuric acid plant, which aims to solve the technical problems of great waste of the existing dynamic wave dilute acid and large load of subsequent sewage treatment.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a recovery processing method of power wave dilute acid in a sulfuric acid plant comprises the following steps:

(1) taking the power wave dilute acid between the vehicles, removing impurities in the power wave dilute acid by adopting membrane filtration, wherein the iron content in the power wave dilute acid after impurity removal is lower than 500 ppm;

(2) the diluted acid after impurity removal is used for bleaching metatitanic acid in the production process of titanium dioxide.

Preferably, in step (1), the membrane used for membrane filtration is an inorganic ceramic membrane.

Preferably, in step (2), the dilute acid is H₂SO₄:TiO₂A substance of 1:5 to 1:8The amount ratio is added to the bleaching process.

Preferably, in the step (2), the iron content of the metatitanic acid before bleaching is 2000-3000 ppm.

Preferably, in the step (2), the content of the trivalent titanium is 0.3-0.8 g/L.

Preferably, in the step (2), the bleaching and curing are carried out for 90 minutes, and then washing is carried out, wherein the washing water consumption is not less than 20 times of the total titanium content.

A metatitanic acid bleaching section is a process of reducing impurities such as Fe and the like in metatitanic acid slurry by using trivalent titanium under an acidic condition and then washing the reduced impurities to remove the impurities, 98 percent sulfuric acid is added at present to ensure an acidic environment, but in actual production, a company finds that the concentration of the added acid is not strictly required as long as the total acid amount and the acid purity are enough, and if dynamic wave dilute acid generated by sulfuric acid production of the company is preliminarily purified and then bleached by replacing 98 percent sulfuric acid in combination with the existing production condition, the cost is greatly reduced.

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

1. the method is used for bleaching metatitanic acid after concentration and membrane filtration, the Fe content of the bleached slurry is within 30ppm after the slurry is washed twice, the brightness of calcined kiln waste is more than or equal to 93.8, the content of other impurities is also at a normal level, and the product quality is not influenced, so that the technical scheme provided by the invention can effectively utilize dynamic wave dilute acid, reduce the use amount of 98% sulfuric acid, achieve the purposes of recycling side waste, saving energy and reducing emission, and expect to bring about 26 ten thousand yuan of economic benefit every year;

2. the method recycles the dynamic wave dilute acid, produces products with higher added value, and has important influence on the sustainable development of China;

3. the invention provides a new idea for the whole chemical production industry in the aspects of waste utilization and environmental protection.

Detailed Description

The present invention is further illustrated by the following examples, which include, but are not limited to, the following examples.

Example 1

In the embodiment, by recycling the side waste kinetic wave dilute sulfuric acid generated in the sulfuric acid production process of the titanium dioxide factory, the side waste kinetic wave dilute sulfuric acid is filtered and purified to replace concentrated sulfuric acid to be used in the bleaching process in the titanium dioxide production.

Inter-vehicle dynamic ripple acid, H₂SO₄The concentration is 17%, and elements such as iron and the like in the inorganic ceramic membrane are removed by an acid-resistant membrane after the inorganic ceramic membrane is used for filtration. The part of dilute acid is detected, the test result shows that the iron content is lower than 200ppm, and then the diluted acid is used for the bleaching process of metatitanic acid washing and beating slurry, and the iron content in the material before bleaching can reach about 2000-3000 ppm. The resultant product was washed with 20-fold desalted water, and then subjected to salt treatment and calcination to analyze changes in brightness and whiteness.

In this embodiment:

(1) purifying dynamic wave diluted acid: the result after the dynamic wave dilute acid inorganic ceramic membrane filtration shows that the impurity content in the dilute acid can be remarkably reduced to be within 500ppm, and the iron content in the material before bleaching can reach about 2000-3000 ppm, so the dilute acid can be used for the bleaching process;

(2) the dosage of diluted acid is as follows: controlling the acid content in bleaching with H₂SO₄:TiO₂Adding bleaching process in the ratio of 1:5, 1:6, 1:7 and 1:8, wherein the content of trivalent titanium is 0.3-0.6 g/L, bleaching and curing for 90 minutes, and then washing with water, wherein the amount of washing water is 20 times of the total titanium content. The result shows that the bleaching effect is better when the added acid amount is larger, and the iron content of the filter cake of the second washing can meet the index requirement.

Example 2

In this example, the purification effect of dynamic wave diluted acid membrane filtration was examined, and the purified diluted acid was added to a bleaching tank for bleaching, followed by two washes to examine the bleaching effect.

The treatment is carried out according to the operation specification, and the specific scheme is that the dilute acid is discharged to a dilute acid storage tank by dynamic wave washing and then is sent to a membrane filtration system to filter out impurities and iron. The removed clear acid is sent to a dilute acid finished product storage tank for standby, a large acid preparation tank is added because the power wave waste acid has low yield and large concentration fluctuation, and a small amount of finished product 98 acid is added to stabilize the concentration of the dilute acid to about 20 percent. And then adding 20% diluted acid into a bleaching tank for bleaching, wherein the diluted acid is obtained by adding the diluted acid into the bleaching tank according to the proportion of acid to titanium of 1:5, bleaching with the addition of the trivalent titanium of 0.63 g/L.

And after bleaching and curing for at least 90min, transferring the mixture to a two-washing filter press for washing, according to the prior art, testing the iron content after pulping, and performing salt treatment, calcination and other processes after the iron content is qualified.

In the embodiment, the effect of removing impurities in the dynamic wave dilute acid by membrane filtration is better, the dilute acid is completely clarified without solid impurities, the iron content in the dilute acid is obviously reduced, and the iron content of a plurality of batches of materials is lower than 2000 ppm. The concentration is regulated by concentrated sulfuric acid to be stabilized at about 20 percent, and the detected iron content is 1667 ppm. Adding the purified dilute acid into a bleaching tank, adding trivalent titanium and calcined seed crystals, curing for 120min, and transferring to a double-washing filter press for washing. The result shows that the secondary washing effect is unstable, the iron content of partial materials exceeds the standard, and the iron content introduced into the dynamic wave diluted acid is higher, so that the content of trivalent titanium is lower, and the metatitanic acid cannot be well bleached.

Example 3

This example examines the effect of the amount of added trivalent titanium on washing. In addition, the clear liquid flux during the filtration of dynamic wave diluted acid is planned to be reduced so as to improve the filtration effect, further reduce the iron content and reduce the influence of the iron content on bleaching.

Treating according to the operating specification, wherein the specific scheme is that the dilute acid is discharged to a dilute acid storage tank by dynamic wave washing, then the dilute acid is sent to a membrane filtration system to filter out impurities and iron, and the clear liquid flux is reduced to 15m³And about/h. The removed clear acid is sent to a dilute acid finished product storage tank for standby, a large acid preparation tank is added because the power wave waste acid has low yield and large concentration fluctuation, and a small amount of finished product 98 acid is added to stabilize the concentration of the dilute acid to about 20 percent. And then adding 20% diluted acid into a bleaching tank for bleaching, wherein the diluted acid is obtained by adding the diluted acid into the bleaching tank according to the proportion of acid to titanium of 1:5, bleaching with the addition of the trivalent titanium of 0.6, 0.8 and 1.0g/L respectively.

And after bleaching and curing for at least 90min, transferring the mixture to a two-washing filter press for washing, according to the prior art, testing the iron content after pulping, and performing salt treatment, calcination and other processes after the iron content is qualified.

And (4) conclusion: the filtration effect of the dilute acid is improved after the flow of clear liquid is reduced during membrane filtration, the iron content is obviously reduced compared with that of the example 2, and the iron content reaches 640 ppm. Then concentrated sulfuric acid is adopted to adjust the concentration to be stabilized at about 20%. Adding the purified dilute acid into a bleaching tank, adding trivalent titanium and calcined seed crystals, curing for 120min, and transferring to a double-washing filter press for washing.

The purified dilute acid is sent to an acid preparation tank, concentrated sulfuric acid is added to adjust the concentration to be about 20% for a subsequent bleaching process, the dilute acid is transferred to a two-washing filter press for washing after bleaching and curing for about 120min, the iron content of part of two-washing pulping materials is 14ppm, 26ppm and 243ppm respectively, and the fact that the adding amount of the trivalent titanium has a certain influence on the whitening effect is proved.

Example 4

In the embodiment, the iron content of the dynamic wave diluted acid is adjusted by adjusting the membrane flux, and then the bleaching acid amount and the trivalent titanium amount are optimized.

Treating according to the operating specification, wherein the specific scheme is that the dilute acid is discharged to a dilute acid storage tank by dynamic wave washing, then the dilute acid is sent to a membrane filtration system to filter out impurities and iron, and the clear liquid flux of a new membrane skid block is reduced to 15m³And about/h. And adding 98 acid into the removed clear acid to adjust the concentration of the dilute acid to be stabilized to about 20 percent. And then adding 20% diluted acid into a bleaching tank for bleaching, wherein the bleaching is carried out according to the acid-titanium ratio of 1:5, 1:6 and 1:7 and the addition of the trivalent titanium is respectively 0.6, 0.7 and 0.8g/L according to the total titanium content of bleaching.

And after bleaching and curing for at least 90min, transferring the mixture to a two-washing filter press for washing, according to the prior art, testing the iron content after pulping, and performing salt treatment, calcination and other processes after the iron content is qualified.

And (4) conclusion: after the novel filtering membrane is replaced, the impurity removal effect is good, the transmembrane pressure difference is greatly increased, the obtained dilute acid is clear and free of impurities, and the iron content is 200-800 ppm. Regulating the concentration to be about 20% by concentrated sulfuric acid, adding the purified dilute acid into a bleaching tank, adding trivalent titanium, calcining seed crystals, curing for 120min, and transferring to a double-washing filter press for washing. The result shows that the second washing effect is better, and the bleaching effect has an obvious relation with the addition of the sulfuric acid. The smaller the amount of the diluted acid added, the less effective the sulfuric acid dissolves the iron hydroxide during bleaching, making it difficult to remove. The adding amount of the sulfuric acid during bleaching is determined to be the acid-titanium ratio of 1:6 in comprehensive consideration, so that the cost is saved, and the removal effect is basically stable.

The purified dilute acid is sent to an acid preparation tank, and concentrated sulfuric acid is added to adjust the concentration to be about 20 percent for the subsequent bleaching process. Bleaching process data are as follows:

total titanium before bleaching	Acid concentration before bleaching	Acid concentration after bleaching	Post-bleaching trivalent titanium
				304.3	29.42g/L	25.36g/L	0.28g/L
314.9	28.89g/L	24.59g/L	0.35g/L
				294.6	27.01g/L	23.39g/L	0.34g/L

After bleaching and curing for about 120min, the pulp is washed in a two-washing filter press, and the relationship between the iron content and the acid content of the two-washing pulping material is as follows:

bleaching acid titanium ratio	Amount of trivalent titanium added before bleaching	Content of iron washed two times
			1:5	0.6	18ppm
1:6	0.6	33ppm
			1:7	0.7	74ppm
1:6	0.7	14ppm
			1:6	0.8	22ppm

The above-mentioned embodiment is only one of the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, but all the insubstantial modifications or changes made within the spirit and scope of the main design of the present invention, which still solve the technical problems consistent with the present invention, should be included in the scope of the present invention.