WO2013020431A1

WO2013020431A1 - Method for recycling concentrate residues of titanium dioxide waste acid

Info

Publication number: WO2013020431A1
Application number: PCT/CN2012/078213
Authority: WO
Inventors: 何刚; 蔡平雄; 文军; 谭明红; 李伟; 朱全芳
Original assignee: 四川龙蟒钛业股份有限公司
Priority date: 2011-08-11
Filing date: 2012-07-05
Publication date: 2013-02-14
Also published as: CN102372306A

Abstract

Provided is a method for recycling concentrate residues of a titanium dioxide waste acid, comprising the steps of: pulping the concentrate residues of the waste acid, adding an excess of iron thereto so as to convert the sulphuric acid in the concentrate residues into ferrous sulphate and convert the ferric iron in the concentrate residues into ferrous iron so as to form ferrous sulphate; cooling and crystallizing the reacted slurry, rapidly separating same to obtain a mixture of ferrous sulphate heptahydrate and ferrous sulphate monohydrate; mixing the above mixture with at least one of sulphur and iron pyrite, controlling the ratio of iron and sulphur, calcinating at 600°C - 900°C, and controlling the oxygen content; subjecting the flue gas generated during calcination to procedures such as washing, dedusting, and demisting, so as to obtain pure sulphur dioxide for preparing sulphuric acid; washing and separating the cinder during calcination to obtain iron trioxide residues of high quality.

Description

Method for recycling and utilizing titanium white powder waste acid concentrated slag

3⁄4 ^ field

The invention relates to a "three wastes" treatment method for titanium white powder and sulfuric acid industry, in particular to a method for preparing sulfuric acid and high-grade iron oxide slag by pretreating titanium white waste acid concentrated slag.

Background technique

The production of titanium dioxide is generally divided into a sulfuric acid process and a chloride process. Due to the limitations of raw materials and technology, most of the titanium dioxide production enterprises currently use the sulfuric acid process.

In the production process of sulfuric acid titanium dioxide, the hydrolyzed metatitanic acid slurry is filtered to obtain a large amount of impurities, and the waste sulfuric acid contains 20-30% of dilute sulfuric acid. For the treatment of waste acid, the sulfuric acid method titanium dioxide manufacturers generally use concentration or acid distribution to enhance the concentration of sulfuric acid and reduce impurities in the acid, which facilitates the recycling of waste acid. At present, most factories increase the concentration of spent acid to 50 to 55% to precipitate most impurities, and then remove the precipitate by solid-liquid separation. The recovered sulfuric acid can be further utilized, for example, the patent of CN101214931, which describes a titanium white hydrolysis waste acid concentration process and the quality and use of concentrated sulfuric acid. The precipitates precipitated by the recovery of concentrated sulfuric acid are commonly referred to as concentrated slag. The main components of the concentrated slag are sulfates of various metals. The typical components (in terms of oxide mass ratio) are: free H ₂ S0 ₄ 10-30%, T1O2 1.0-2.5%, AI2O3 0.15-0.35%, Fe ₂ 0 ₃ 20-28.6% MgO 1.7-3.0%, H ₂ 0 15-25%. The concentrated slag contains some useful ingredients, such as ferrous sulfate, but due to concentrated slag It contains a large amount of impurities and sulfuric acid. It is difficult to recycle. At present, alkaline materials are generally used for stacking and neutralizing. Due to the large amount of treatment, it will occupy a huge pile slag site and have certain impact on the environment. At present, in addition to the use of concentrated slag to produce a feed ferrous iron in the patent No. 200910312742.7, the inventor is further developing other application fields of concentrated slag.

The main raw material for the production of titanium dioxide by sulfuric acid method is titanium concentrate and sulfuric acid, so the titanium dioxide factory is generally equipped with a sulfuric acid workshop. The raw material for the preparation of sulfuric acid in the industry is one or more of sulfur, pyrite and pyrite, which is burned or calcined in the air to obtain sulfur dioxide fumes. It is then passed through a purification device such as a cyclone. After purification by electrostatic precipitator, pure sulfur dioxide is obtained, then sulfur dioxide is catalytically oxidized to sulfur trioxide, and two turns and two suctions are used to obtain concentrated sulfuric acid. Chinese Patent Application No. 03119051.0 discloses a method for preparing sulfuric acid by mixing calcination of low-grade sulfur and pyrite; and Chinese patent application No. 200910042741.5 also uses sulfur in order to improve the grade of burned residue after roasting. , pyrite, pyrrhotite, sulfur-containing magnetite roasting to prepare sulfuric acid. The raw materials for the preparation of sulfuric acid in the above two patents are all grades of pyrite, sulfur, etc., and various ores require cost. From the composition analysis of titanium dioxide waste acid concentrated slag, it is mainly iron and sulfur two elements, and the main components of the ore, so that the concentrated slag can be considered to be used in the preparation of sulfuric acid, on the one hand, waste utilization, Obtain high value-added products, but need to overcome the influence of other impurities such as waste acid and moisture in the concentrated slag. For example, the higher the acid content in the concentrated slag, the more the amount of sulfur trioxide is decomposed during calcination. The sulfur trioxide can not only be used, but also needs to be washed and removed, otherwise it will corrode the equipment; the higher the water content, the more acid it combines, and the higher the water vapor, the more the drying and purification load of the subsequent process is added, so The lower the acid and water content, the better.

Summary of the invention

4: ^^::^ 3 is: In response to the above problems, a method for recycling and utilizing titanium dioxide waste acid concentrated slag is provided.

The technical solution adopted by the present invention is as follows: A method for recycling and utilizing titanium white powder waste acid concentrated slag, comprising the following process steps:

Concentrated slag pretreatment

(1) mixing the titanium dioxide waste acid concentrated slag and the ferrous sulfate heptahydrate into the mother liquor produced by the ferrous sulfate monohydrate crystal (the main components are iron, sulfuric acid and water), mixing and beating to obtain a slurry, and controlling the specific gravity of the slurry to be 1.2. ~1.4, calculate the amount of iron powder according to the mass of free sulfuric acid 50~100%, and slowly add iron powder, react at temperature of 50 °C ~ 90 °C for l~3h, adjust the mass content of acid 4~10%, The iron content in the pulp is 10~30% _;

(2), cooling crystallization, separation:

The slurry after the above reaction is transferred into a cooler, and the temperature is slowly lowered at a rate of 1 to 3 ° C/min, and the crystal is cooled for 1 to 2 hours, and the final temperature is cooled to 10 to 25 ° C, and then rapidly separated to obtain a heptahydrate sulfate. a mixture of iron and ferrous sulfate monohydrate;

(3), mixing ratio, roasting:

Mixing the ferrous sulfate heptahydrate and the ferrous sulfate monohydrate obtained in the step (2) with at least one of sulfur and pyrite, and controlling the ratio of iron and sulfur in the mixed material, and then calcining, and the calcination temperature is 600-900 ° C, the control oxygen content during roasting is 4-8%;

(4), washing, purification:

The flue gas obtained during the calcination in the step (3) is subjected to washing, dust removal, defogging, and the like to obtain pure sulfur dioxide for preparing sulfuric acid. Preferably, the calcined slag obtained after the calcination in the step (3) is washed and separated to obtain a high-grade iron oxide slag. The high-grade iron oxide slag has an iron content of more than 65% and is suitable as a raw material for steel mills.

Preferably, the acid content in the slurry in the step (1) is 6 to 8%, and the iron content is 15 to 25%.

Preferably, the acid content of the ferrous sulfate heptahydrate and the ferrous sulfate monohydrate obtained in the step (2) is 6 to 8%, and the moisture content is 4 to 10%, that is, the control acid and water contents are not exceeded, which is favorable for subsequent baking.

Preferably, in step (3), the ratio of iron and sulfur in the mixture of the mixture of ferrous sulfate heptahydrate and ferrous sulfate monohydrate and at least one of sulfur and pyrite is 1:4~1:8.

Preferably, the calcination described in the step (3) is carried out in a boiling furnace, and the calcination strength is 10 to 14 tons/(m ² .h; >, the operating gas velocity at the time of roasting is 10-15 m/s, and the residence time is 8 -15s. At present, the general boiling furnace ^ ^^ :::, the tonnage of roasting ore per square meter area is 17~20 tons / (m ² .h), and the patent application reduces the roasting strength by increasing the roasting area. .

The inventor of the present patent first pretreated the concentrated slag based on the patent application No. 200910312742.7, and then improved and innovated in the process and equipment, and obtained better results.

In the FeS0 ₄ ~H ₂ S0 ₄ ~H ₂ 0 ternary system, when the temperature is constant, the solubility of ferrous sulfate decreases with the increase of sulfuric acid concentration; when the concentration of sulfuric acid is constant, the solubility increases with the increase of temperature. When the concentration of H ₂ S0 _{4 in the} solution is constant, the solubility of FeS0 ₄ has a maximum with the increase of temperature, and the temperature corresponding to the maximum decreases with the decrease of FeS0 ₄ content in the solution. It has already been explained in the patent application 200910312742.7.

According to the above mechanism, the present invention beats the waste acid concentrated slag, and under the premise of cost, excessive iron powder or iron skin is added to the concentrated slag after beating, and the reaction is carried out at a temperature of 50 ° C to 90 ° C. 3h, the sulfuric acid in the concentrated slag is converted into ferrous sulfate, and the ferric iron which may be present in the concentrated slag is converted into ferrous iron to form ferrous sulfate, thereby removing not only the residual sulfuric acid and ferric iron in the concentrated slag. Moreover, the content of ferrous sulfate in the concentrated slag is greatly increased, and the proportion of iron is also greatly increased. The slurry after the above reaction is slowly cooled at a rate of 1 to 3 ° C/min, and the crystals are cooled to promote the conversion of the ferrous sulfate monohydrate having a particle diameter of 2 to 20 μm in the waste acid concentrate to a particle size of 200~500 μm of ferrous sulfate heptahydrate is then separated by centrifugation to obtain concentrated slag with low acid and low water content, which ensures the subsequent process to reduce the production of sulfur trioxide.

Mixing the mixture of heptahydrate and ferrous sulfate monohydrate obtained in the previous step with one or more of sulfur and pyrite to ensure the mass ratio of iron and sulfur after mixing is 1:4~1:8, the proportion of sulfur It is relatively high, on the one hand, it ensures that the decomposition of ferrous sulfate and water increases enough heat, and also ensures that the content of S0 ₂ in the obtained flue gas is high. Conducive to the subsequent acid production process. In view of the relatively slow calcination reaction of the concentrated slag, after extensive experimentation, the inventors made innovative innovations on the boiling furnace, which reduced the calcination strength of the boiling furnace. The roasting strength of the general boiling furnace was 17-20 tons/(m ² .h). The boiling furnace has a calcining strength of 10 to 14 tons/(m ² .h). The boiling furnace improved by the patent application mainly increases the baking area, and can increase the roasting area by increasing the area of the boiling furnace bed. Reducing the calcination strength, thereby reducing the gas velocity, increasing the reaction time of the material, fully decomposing the acid in the concentrated slag, facilitating subsequent purification and improving the grade of the slag, reducing the calcination strength, and the gas velocity is the conventional gas velocity. 30%-50%, increase the reaction residence time of the mixed ore in the furnace, find the best roasting temperature of 600-900 ° C, control the oxygen content of 4-8%, so that the calcined product is as much as possible , inhibits the production of sulfur trioxide and reduces the acid content in the washing wastewater. In::::,::;:) reduction and subsequent suitable iron-sulfur ratio, to ensure that the slag is washed and separated to obtain high-grade iron oxide slag, iron content greater than 65%, suitable for steel mill raw materials .

Compared with the prior art, the technical effect of the invention: The invention pre-processes the waste acid concentrated slag into high value-added sulfuric acid and high-grade ferric oxide slag, turning waste into treasure and protecting the environment, Saved resources. The pretreatment of titanium white waste acid concentrated slag to produce sulfuric acid can fully utilize the production and distribution of sulfuric acid titanium dioxide, reduce equipment investment, and achieve the goal of circular economy, energy saving and emission reduction.

Specific 3⁄461 way

The invention will now be described in detail.

In order to make the objects, the technical solutions and the advantages of the present invention more comprehensible, the present invention will be further described in detail below with reference to the embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting

Wei case 1

This embodiment includes the following process steps:

(1) Pretreatment of concentrated slag:

In the FRP reactor, the mother liquor produced by 8m ³ -water ferrous sulfate (iron content 7.23%, acid content 2.45%) was added, and 12 tons of titanium white waste acid concentrate was added under stirring (Fe mass content 18.2) %, H ₂ S0 ₄ mass content 14.3%), the concentrated slag and the mother liquor are mixed and beaten, the specific gravity of the slurry is controlled to 1.3, the temperature is raised to 70 ° C, the fan is turned on, and then 750 kg of iron powder is slowly added, and the iron powder is added for 1 hour. After the iron powder reaction was completed, 4 m ^{3 of the} wet ferrous sulfate monohydrate mother liquor was added and maintained at this temperature. At this time, the mass of the slurry iron is 15.89%, and the acid content is 4.56%; (2), cooling crystallization, separation:

The acid-reduced slurry is transferred to a vacuum cooler, slowly cooled at a rate of rC/min, and the slurry is cooled to 20 ° C for 2 hours to obtain a seven-water and a crystal having a crystal particle size of about 0.23 mm. A mixture of ferrous sulfate and water; selected for rapid centrifugation to obtain 16.5 tons of heptahydrate and ferrous sulfate monohydrate (iron content 19.43%, water content 6.9%), turbid filtrate containing metatitanic acid 11.3 tons, filtrate iron content 6.09% , obtaining metatitanic acid and clear liquid for reuse or for other purposes;

(3), mixing ratio, roasting:

The obtained ferrous sulfate heptahydrate was 16.5 tons, and the ratio of iron to sulfur was 16.2 tons of sulfur in a ratio of 1:4. In the improved boiling furnace, the calcination strength was 10 tons/(m ² .h), and the calcination gas velocity was 10 m/ s, the residence time is 15s roasting, the control oxygen content is 6%;

(4), washing, purification:

The flue gas obtained in (3) is subjected to washing, dust removal, defogging and the like to obtain pure sulfur dioxide to prepare sulfuric acid, thereby obtaining 98% concentrated sulfuric acid 50.5 tons; and the obtained calcined residue is washed and separated to obtain high grade. The iron oxide slag is 6.4 tons, the iron content is 65.4%, and the raw materials of the steel mill are sent.

Wei case 2

This embodiment includes the following process steps:

(1) Pretreatment of concentrated slag:

In the FRP reactor, the mother liquor produced by 8m ³ -water ferrous sulfate (iron content 7.23%, acid content 2.45%) was added, and 12 tons of titanium white waste acid concentrate was added under stirring (Fe mass content 18.2) %, H ₂ S0 ₄ mass content 14.3%), mixing the concentrated slag with the mother liquor, controlling the specific gravity of the slurry to 1.3, heating up to 70 ° C, turning on the fan, then slowly adding 750 kg of iron powder, iron powder addition time 2 hours, iron After the completion of the powder reaction, 4 m ^{3 of the} wet ferrous sulfate monohydrate mother liquor was added and maintained at this temperature. At this time, the mass of the slurry iron is 16.51%, and the acid content is 3.15%;

The other steps are the same as those in the first embodiment, and finally 98% of concentrated sulfuric acid is obtained, which is 51.7 tons. The slag obtained by (3) is washed and separated to obtain 6.6 tons of high-grade iron oxide slag, and the iron content is 66.0%. raw material. Male case 3

This embodiment includes the following process steps:

(1) Pretreatment of concentrated slag:

In the FRP reactor, the mother liquor produced by adding 8m ³ -water ferrous sulfate (iron content 7.23%, acidity) The content of 2.45%), under stirring, add 12 tons of titanium white waste acid concentrate (Fe mass content 18.2%, H ₂ S0 ₄ mass content 14.3%), mix the concentrated slag with the mother liquor and beat to control the specific gravity of the slurry. 1.3 Warm up to 70 °C, turn on the fan, then slowly add 750kg of iron powder, iron powder for 3 hours, after the iron powder reaction is finished, add 4 m ^{3 of} wet ferrous sulfate mother liquor and maintain the temperature. At this time, the mass of the slurry iron is 16.51%, and the acid content is 3.15%;

The other steps are the same as in the first embodiment, obtaining 98% concentrated sulfuric acid 52.8 tons; the (3) obtained slag is washed and separated to obtain high-grade iron oxide slag 6.7 tons, iron content 66.2%, raw materials for the steel mill . Male case 4

This embodiment includes the following process steps:

\丄

In the FRP reactor, 8 m ³ - water ferrous sulfate production mother liquor (iron content 7.23%, acid content 2.45%) was added, and 12 tons of titanium white waste acid concentrate (Fel 8.2 ° /, H ₂ S04l4.3%), the concentrated slag is mixed with the mother liquor to be beaten, the specific gravity of the slurry is controlled to 1.3, the temperature is raised to 70 ° C, the fan is turned on, then 1000 kg of iron powder is slowly added, the iron powder is added for 3 hours, and the iron powder reaction ends. Thereafter, 4 m ^{3 of} wet ferrous sulfate monohydrate mother liquor was added and maintained at this temperature. At this time, the iron content of the slurry is 19.01%, and the acid content is 3.12%;

(2), cooling crystallization, separation:

The acid-reduced slurry is transferred to a vacuum cooler, slowly cooled at a rate of rC/min, and the slurry is cooled to 20 ° C for 2 hours to obtain a seven-water and a crystal having a crystal grain size of about 0.34 mm. A mixture of water ferrous sulfate. Choose fast centrifugation. Obtained 16.8 tons of ferrous sulfate heptahydrate and ferrous sulfate monohydrate (iron content 21.2%, water content 5.1%), 11.6 tons of turbid filtrate containing metatitanic acid, and 6.31% iron content of filtrate, obtaining metatitanic acid and clear liquid back Use or for other purposes;

(3), mixing ratio, roasting:

The obtained heptahydrate and ferrous sulfate monohydrate mixture 16.8 tons of iron: sulfur ratio of 1:6 added sulfur tons of 24.2 tons, in the modified boiling furnace according to the roasting strength of 10 / (m2.h; > roasting, The calcination gas velocity is 10 m/s, the residence time is 15 s, the calcination temperature is 750 ° C, and the controlled oxygen content is 6%;

(4), washing, purification:

The flue gas obtained in (3) is subjected to washing, dust removal, defogging and the like to obtain pure sulfur dioxide to prepare sulfuric acid to obtain 98.8% of sulfuric acid; and the obtained calcined residue is washed and separated to obtain high-grade three. The iron oxide slag is 7.5 tons, and the iron content is more than 66.8%. Example 5

Step (1) (2) of the embodiment is the same as the embodiment 4

(3), mixing ratio, roasting:

The obtained 16.8 tons of ferrous sulfate heptahydrate is added to the pyrite of 20.1 tons and 8.2 tons of sulfur by a ratio of iron to sulfur of 1:6, and calcined at a torrefaction intensity of 10 / (m2.h) in a modified boiling furnace. , the calcination gas velocity is 10m / s, the residence time is 15s, the calcination temperature is 800 ° C, the control oxygen content is 8%;

(4), washing, purification:

The flue gas obtained in (3) is subjected to washing, dust removal, defogging and the like to obtain pure sulfur dioxide to prepare sulfuric acid to obtain 74.5 tons of 98% sulfuric acid; and the calcined residue obtained in (3) is washed and separated to obtain high-grade three two. :: ', II.:, iron content 67.5%, raw materials for steel mills.

Example 6

This embodiment includes the following process steps:

(1) (2) Steps are the same as in the example 4.

The obtained heptahydrate and ferrous sulfate monohydrate mixture 16.8 tons of iron: sulfur ratio of 1:6 added sulfur tons of 24.2 tons, in the modified boiling furnace according to the roasting strength of 14 / (m2.h; > roasting, The calcination gas velocity is 14m/s, the residence time is lis, the calcination temperature is 750 ° C, and the controlled oxygen content is 6%;

(4), washing, purification:

The flue gas obtained in (3) is subjected to washing, dust removal, defogging and the like to obtain pure sulfur dioxide to prepare sulfuric acid to obtain 98.3% of sulfuric acid; and the obtained calcined residue is washed and separated to obtain high-grade three. 7.4 tons of iron oxide slag, iron content greater than 66.5%, raw materials for steel mills.

Comparative example 1

This comparative example 1 directly combines the untreated concentrated slag with sulfur, including the following process steps:

(1), mixing ratio, roasting:

12 tons of concentrated slag according to iron: sulfur ratio of 1:4 added sulfur tonnage 15.8 tons, in a modified boiling furnace according to the roasting strength of 10 tons / (m2.h) roasting, roasting temperature of 750 ° C, control of oxygen The content is 6%;

(2), washing, purification:

The flue gas obtained in (1) is subjected to washing, dust removal, defogging and the like to obtain pure sulfur dioxide to prepare sulfuric acid, thereby obtaining 98% concentrated sulfuric acid of 50.2 tons; and the calcined residue obtained in (1) is washed and separated to obtain high grade. 5.6 tons of iron oxide slag, iron content of 60.1%, raw materials for steel mills. Comparative example 2

This comparative example 2 directly uses sulfur to produce acid, including the following process steps:

(1), mixing ratio, roasting:

15.8 tons of sulfur to be calcined in a modified boiling furnace at a calcination strength of 10 tons / (m2.h), a calcination temperature of 750 ° C, a controlled oxygen content of 6%;

(2), washing, purification:

The flue gas obtained in (1) is subjected to washing, dust removal, defogging and the like to obtain pure sulfur dioxide to prepare sulfuric acid, thereby obtaining 98% concentrated sulfuric acid of 47.8 tons.

The flue gas components of the above examples and comparative examples are shown in Table 1.

Table 1 different «Example smoke component quality «

Table 2 The quality of sulfuric acid prepared in different examples and the iron content of tailings - -. τ _; mass (ton) tail cut mass (ton) tail slag total e% comparative example i 50. 2 5. 6 60. 1

Comparative copper 2 47. 8

Buying a pour 1 50. 5 6, 4 65. 4

Example BL 7 6, 6 66. 0

Real deletion 3 _t < p 6. 7 66. 2

Implementation 75. g 7. 5 66. 8

Example 5 74. 5 12. 1 67. 5

3⁄43⁄4 6 75. 3 7. 4 66. 5

Analysis of the results of the examples:

(1) As seen from Comparative Examples 1, 2 and all of the examples, the method for recycling concentrated slag by the present application can increase the yield of sulfuric acid and obtain high-grade iron oxide slag;

(2) Comparative Example 1-3 It was found that the reaction time of adding iron powder is a key parameter, which has an important influence on improving the quality of the slurry iron and reducing the acid content.

(3) Comparing the results of Examples 1-3 and Example 4, it is found that the amount of iron powder added to the pre-treatment of the concentrated slag is increased, and the grade of the iron slag slag can be improved, and the iron and sulfur ratio of the mixture can be kept unchanged. Increase the production of sulfuric acid;

(4) Comparing the results of Example 4 and Example 5, it was found that one or both of the sulfur and the pyrite can be used for the calcination, and the sulfur can be used to increase the yield of sulfuric acid, and the addition of pyrite can be improved. Grade of iron oxide slag;

In Comparative Example 4 and Example 6, it was found that the strength at the time of calcination was relatively low, the calcination gas velocity was low, and the residence time was long, which was favorable for increasing the yield of sulfuric acid and the grade of iron oxide slag.

Claims

A method for recycling and utilizing titanium white powder waste acid concentrated slag, comprising the following process steps:

(1) Pretreatment of concentrated slag:

The titanium dioxide waste acid concentrated slag and the ferrous sulfate heptahydrate are converted into the mother liquor produced by the ferrous sulfate monohydrate crystal to be mixed and beaten to obtain a slurry, and the specific gravity of the slurry is controlled to be 1.2 to 1.4, calculated according to the mass of the free sulfuric acid of 50 to 100%. The amount of iron powder, and slowly add iron powder, react at a temperature of 50 ° C ~ 90 ° C for 1 ~ 3h, adjust the mass content of acid 4 ~ 10%, the iron content of the slurry is 10 ~ 30%;

(2), cooling crystallization, separation:

The slurry after the above reaction is transferred into a cooler, slowly cooled at a rate of 1 to; TC/min, cooled for 1 to 2 hours, cooled to a final temperature of 10 to 25 ° C, and then rapidly separated to obtain ferrous sulfate heptahydrate. And sulfuric acid monohydrate

(3), mixing ratio, roasting:

(4), washing, purification:

The flue gas obtained in the step (3) is subjected to washing, dust removal, defogging, and the like to obtain pure sulfur dioxide for preparing sulfuric acid.

The method for recycling and utilizing titanium ash waste acid concentrated slag according to claim 1, wherein the slag obtained after the calcination in the step (3) is washed and separated to obtain high-grade iron oxide slag.

The method for recycling and utilizing titanium white powder waste acid concentrated slag according to claim 1, wherein the acid content in the slurry in the step (1) is 6 to 8%, and the iron content is 15 to 25%.

The method for recycling and utilizing titanium ash waste acid concentrated slag according to claim 1, characterized in that the acid content of the ferrous sulfate heptahydrate and the ferrous sulfate monohydrate obtained in the step (2) is 6 to 8%, and the moisture content is 4 ~10%.

The method for recycling and utilizing titanium dioxide waste acid concentrated slag according to claim 1, wherein in the step (3), the mixture of ferrous sulfate heptahydrate and ferrous sulfate monohydrate and at least one of sulfur and pyrite is controlled. The ratio of iron and sulfur in the mixed material is 1:4 to 1:8.

6. The method for recycling and utilizing titanium dioxide waste acid concentrated slag according to claim 1, wherein the calcination in the step (3) is carried out in a boiling furnace, and the calcination strength is 10 to 14 tons/(m ² .h). ), the operating gas velocity during calcination is 10_15m/s, and the residence time is 8_15s.