CN108726578B - Ferrous sulfate continuous crystallization process in sulfuric acid method titanium dioxide production - Google Patents
Ferrous sulfate continuous crystallization process in sulfuric acid method titanium dioxide production Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 96
- 230000008025 crystallization Effects 0.000 title claims abstract description 77
- 238000002425 crystallisation Methods 0.000 title claims abstract description 76
- 235000003891 ferrous sulphate Nutrition 0.000 title claims abstract description 55
- 239000011790 ferrous sulphate Substances 0.000 title claims abstract description 55
- 229910000359 iron(II) sulfate Inorganic materials 0.000 title claims abstract description 55
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 title claims abstract description 52
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 title claims abstract description 51
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 30
- 239000004408 titanium dioxide Substances 0.000 title claims abstract description 22
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 title claims abstract 13
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 65
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 65
- 239000010936 titanium Substances 0.000 claims abstract description 65
- 238000001816 cooling Methods 0.000 claims abstract description 45
- 238000007790 scraping Methods 0.000 claims abstract description 24
- 239000002245 particle Substances 0.000 claims abstract description 17
- 239000007788 liquid Substances 0.000 claims description 59
- 239000013078 crystal Substances 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 238000007710 freezing Methods 0.000 claims description 15
- 230000008014 freezing Effects 0.000 claims description 15
- 239000000498 cooling water Substances 0.000 claims description 12
- 239000002826 coolant Substances 0.000 claims description 8
- 230000001105 regulatory effect Effects 0.000 claims description 7
- 230000001276 controlling effect Effects 0.000 claims description 5
- 235000010215 titanium dioxide Nutrition 0.000 abstract description 24
- 238000005265 energy consumption Methods 0.000 abstract description 8
- 239000006227 byproduct Substances 0.000 abstract description 4
- 238000007599 discharging Methods 0.000 abstract description 3
- 238000000926 separation method Methods 0.000 abstract description 3
- 239000012535 impurity Substances 0.000 abstract description 2
- 239000000463 material Substances 0.000 abstract 1
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 44
- 238000003756 stirring Methods 0.000 description 7
- 239000012065 filter cake Substances 0.000 description 5
- 238000001914 filtration Methods 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000005086 pumping Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000012595 freezing medium Substances 0.000 description 1
- 239000005457 ice water Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/14—Sulfates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0004—Crystallisation cooling by heat exchange
- B01D9/0013—Crystallisation cooling by heat exchange by indirect heat exchange
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0059—General arrangements of crystallisation plant, e.g. flow sheets
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a continuous crystallization process of ferrous sulfate in the production of titanium white by a sulfuric acid method, which relates to the related technical field of impurity removal in the production of titanium white by the sulfuric acid method, wherein in the continuous crystallization process of ferrous sulfate in the production of titanium white by the sulfuric acid method, a material titanium solution passes through a tubular heat exchanger and an overhead tank and then enters a wall-scraping type hollow plate cooling continuous crystallizer to realize continuous crystallization through continuous feeding and discharging; the process simplifies the crystallization process, reduces the investment on equipment and reduces the energy consumption, the wall-scraping type hollow plate cooling continuous crystallizer realizes the continuous crystallization and large-scale use of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method, the particle size of ferrous sulfate particles as a byproduct is controlled by adjusting the spiral rotating speed of the crystallizer, the operation of the next separation procedure is facilitated, and the quality of the ferrous sulfate as the byproduct and the yield of the titanium dioxide are improved.
Description
The technical field is as follows:
the invention relates to the technical field related to impurity removal in titanium dioxide production by a sulfuric acid method, in particular to a continuous crystallization process of ferrous sulfate in titanium dioxide production by a sulfuric acid method.
Background art:
at present, the separation of ferrous sulfate in the sulfuric acid method titanium dioxide industry basically adopts vacuum evaporation crystallization, a steam ejector is utilized to form negative pressure in a crystallizer, at the moment, moisture in titanium liquid is evaporated due to the reduction of a boiling point, heat is taken away, and the temperature of the titanium liquid is reduced. The temperature of the titanium liquid system is controlled to reduce the solubility of the ferrous sulfate, so that the ferrous sulfate is crystallized and separated out, and then the filtration is carried out. The method has the advantages of simple operation and wide applicability, but has the defects of long crystallization time, large steam consumption, uneven ferrous sulfate crystal particle size and the like, the titanium liquid (commonly called as crystallized titanium liquid) containing ferrous sulfate crystals is obtained after vacuum crystallization is finished, disc filtration is adopted, and because the ferrous sulfate heptahydrate particles in the filter cake are small and uneven, the titanium liquid is easily wrapped in the ferrous sulfate crystals, the yield of total titanium is reduced, and the free water content of ferrous sulfate is increased.
The existing crystallization process in the titanium dioxide production by the sulfuric acid method has two modes, wherein the mainstream process is a vacuum crystallization process, and the non-mainstream process is intermittent freezing crystallization.
The existing crystallization process principle is as follows: (1) vacuum crystallization: the vacuum crystallization is to reduce the temperature of the titanium liquid by the vacuum flash principle to reach the crystallization temperature of the ferrous sulfate so as to separate out the ferrous sulfate crystals. The prior art adopts a vacuum crystallization tank, and the process flow is as follows: after the titanium liquid enters the vacuum crystallization tank, the titanium liquid stays for about 2 hours, and the titanium liquid starts to be discharged when the titanium liquid is cooled to the required crystallization temperature. In order to achieve the process, a vacuum pump, a steam jet pump and a circulating water device for condensing steam are also required to be equipped. (2) Intermittent freezing and crystallizing: the process principle is that when the titanium liquid is subjected to heat transfer and temperature reduction through a freezing medium to reach a certain temperature, ferrous sulfate is crystallized and separated out. The process comprises the following steps: the titanium liquid enters a freezing crystallization tank, stays in the tank for about 6 hours through chilled water of a heat control coil pipe, and is cooled to a certain temperature, so that ferrous sulfate is crystallized and separated out.
The production processes of the two processes are discontinuous, the titanium liquid can not continuously enter and exit, the energy consumption is very high, the energy consumption of vacuum crystallization is the highest, the energy consumption of freezing crystallization is slightly low, but the freezing crystallization equipment can not be large-scale and only can be suitable for manufacturers with small production scale.
In patent CN 103708566, a method for improving the filtration performance of ferrous sulfate is disclosed, which comprises the following specific operations: taking a clear titanium solution obtained by a sulfuric acid method titanium dioxide production process, wherein the clear titanium solution contains ferrous sulfate, adding an accelerant into the clear titanium solution, and uniformly mixing; putting the clear titanium liquid mixed with the accelerant into ice water for crystallization, keeping stirring in the crystallization process, crystallizing until the temperature of the clear titanium liquid is less than or equal to 20 ℃, obtaining crystallized titanium liquid, and taking out the crystallized titanium liquid; filtering under the condition of negative pressure to obtain a filter cake containing ferrous sulfate crystals of the titanium liquid, and washing while filtering to wash out the titanium liquid in the filter cake. The invention adds an accelerant into the titanium-removing liquid, provides a crystallization center for ferrous sulfate crystallization, promotes the generation of ferrous sulfate heptahydrate, and greatly improves the crystallization speed of ferrous sulfate, thereby shortening the crystallization time. In addition, the ferrous sulfate crystal has uniform particle size and larger particle size, is beneficial to washing a filter cake, can reduce the content of residual titanium in the filter cake and improves the yield of titanium.
In patent CN201510864140.8, a device and a method for producing ferrous sulfate from titanium dioxide by a sulfuric acid process are disclosed, which comprises a device for producing ferrous sulfate from titanium dioxide by a sulfuric acid process, comprising a vacuum crystallization tank, a primary ejector, a secondary ejector, a primary condenser, a secondary condenser, a water ring vacuum pump, and a crystallized titanium liquid storage tank, which are connected in sequence, wherein the top of the vacuum crystallization tank is connected with the primary ejector, the primary ejector is connected with the primary condenser, the top of the primary condenser is connected with the secondary ejector, the secondary ejector is connected with the secondary condenser, the secondary condenser is connected with the water ring vacuum pump, the vacuum crystallization tank is also provided with a feed valve and a discharge valve, the discharge valve is connected with a crystallized titanium liquid storage tank, the method and the device realize the enlargement of the grain size of the ferrous sulfate finished product crystal, and the particle size is uniform, the washing effect of the ferrous sulfate crystal is ensured, and the content of residual titanium liquid in a ferrous sulfate finished product is reduced.
The invention content is as follows:
aiming at the problems, the invention provides a continuous crystallization process of ferrous sulfate in the production of titanium white by a sulfuric acid method. The continuous crystallization process and the equipment used in the process greatly reduce the energy consumption and the economic investment, simplify the process flow and save the resources.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
a continuous crystallization process of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method comprises the following steps:
in the continuous crystallization process of ferrous sulfate in the production of titanium white by a sulfuric acid method, titanium liquid is sent into a tube type heat exchanger; pre-cooling the titanium liquid to 38-45 ℃ in a shell and tube heat exchanger; then the titanium liquid enters a head tank through a conveying pipeline and is continuously metered into a wall scraping type hollow plate cooling continuous crystallizer; the titanium liquid is continuously pushed by a screw in a wall-scraping type hollow slab cooling continuous crystallizer, is cooled by a cooling medium in the hollow slab, is continuously cooled to 12-14 ℃, and the titanium liquid containing ferrous sulfate crystals continuously flows into the next procedure through an outlet, so that the continuous crystallization of ferrous sulfate is realized.
In the process production, the ferrous sulfate crystal particle size is controlled by regulating and controlling the spiral rotating speed of the wall scraping type hollow plate cooling continuous crystallizer, wherein the spiral rotating speed is 10-30 rpm/min.
Wherein the temperature of the circulating cooling water of the shell and tube heat exchanger is controlled to be 25-35 ℃.
Wherein the temperature of the cooling medium of the wall scraping type hollow plate cooling continuous crystallizer is controlled to be 10-20 ℃ below zero.
Wherein the wall-scraping type hollow plate cooling continuous crystallizer inputs and outputs freezing circulating water through a refrigerator, and the temperature of the freezing circulating water is 5-40 ℃ below zero.
Wall scraping type hollow plate cooling continuous crystallizer: multiple rows of hollow cooling plate sheets are combined and arranged in a U-shaped horizontal long groove container, a central stirring shaft penetrates through all the cooling plate sheets, a flow-blocking type separating disc and a plurality of pushing wall-scraping type stirring devices are arranged between every two cooling plate sheets, wall-scraping stirring is carried out to ensure that all cooling surfaces play a wall-cleaning role, the heat transfer and cooling effects are greatly improved, the crystallized titanium liquid enters from one end and is slowly pushed forwards to the other end to overflow and discharge, the titanium liquid is fully contacted with a large number of cooling surfaces and is rapidly cooled, and real rapid continuous crystallization is realized; (1) because a large number of hollow cooling plates are combined and arranged in a U-shaped horizontal long groove-shaped container, the cooling area of the hollow cooling plates is generally 5 to 20 times that of a kettle-type crystallizer with the same volume, and the cooling area is very large; (2) all the spaces in the crystallizer are provided with cooling surfaces at short intervals, so that no cooling dead angle exists, and the crystallization of the titanium liquid is uniform; (3) all the surfaces are provided with wall-cleaning stirring push type scrapers, so that the cooling efficiency of the titanium liquid in the crystallization process is greatly improved, the real rapid cooling crystallization is realized, and one crystallizer can replace dozens or even more kettle type crystallizers; (4) the method realizes real continuous crystallization, and because the wall scraping and cleaning function is always realized in any crystallization process, the heat transfer coefficient and the cooling efficiency of the crystallizer can be always kept unchanged, which cannot be realized by other crystallizers; (5) also can be used for quick batch crystallization; (6) the crystal grain size can be controlled by controlling the stirring speed and the cooling speed.
The invention has the beneficial effects that:
(1) the continuous crystallization process of ferrous sulfate in the sulfuric acid method titanium dioxide production simplifies the crystallization process, reduces the investment equipment and reduces the energy consumption;
(2) in the continuous crystallization process of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method, the particle size of a crystallization byproduct ferrous sulfate can be regulated, the operation of the next separation procedure is facilitated, the quality of the byproduct ferrous sulfate can be improved, and the yield of a main product titanium dioxide is improved;
(3) the method has the advantages that the wall-scraping type hollow plate cooling continuous crystallizer is used in the process flow, so that the continuous crystallization and large-scale use of ferrous sulfate in the production of titanium white by a sulfuric acid method are realized, and the defects that the ferrous sulfate crystallization is discontinuous, the titanium liquid can not continuously enter and exit, the equipment can not be large-sized and the method can only be suitable for manufacturers with small production scale in the traditional and the existing processes are changed.
Description of the drawings:
FIG. 1: a vacuum crystallization process flow diagram;
FIG. 2: a flow chart of a freezing and crystallizing process;
FIG. 3: a flow chart of a continuous freezing crystallization process;
the specific implementation mode is as follows:
in order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
Example 1
A continuous crystallization process of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method comprises the following steps: the method comprises the following steps:
(1) opening a feeding valve of the tube type heat exchanger, starting a feeding pump, and feeding the titanium liquid with the temperature of 55-68 ℃ into the tube type heat exchanger;
(2) pre-cooling the titanium liquid to 37-45 ℃ in a shell and tube heat exchanger;
(3) when the temperature of the titanium liquid in the shell and tube heat exchanger reaches 38-40 ℃, the titanium liquid enters an elevated tank through a conveying pipeline and is continuously metered and enters a scraped-wall hollow sheet cooling continuous crystallizer;
(4) and starting a cooling water refrigerator, opening a cooling water regulating valve, and pumping circulating cooling water into the wall scraping type hollow plate cooling continuous crystallizer, wherein the temperature is controlled to be 10-20 ℃ below zero.
(5) Under the continuous spiral pushing of the scraped-wall hollow slab cooling continuous crystallizer, the titanium liquid is cooled by a cooling medium in the hollow slab in the flowing process, is continuously cooled to 12-14 ℃, and continuously flows into a titanium liquid storage tank in the next process through a discharge port;
in the process production, the ferrous sulfate crystal particle size is controlled by regulating and controlling the spiral rotating speed of the wall scraping type hollow plate cooling continuous crystallizer, wherein the spiral rotating speed is 10-30 rpm/min.
Wherein the temperature of the circulating cooling water of the tubular heat exchanger is controlled to be 25-35 ℃.
Wherein the temperature of the cooling medium of the wall scraping type hollow plate cooling continuous crystallizer is controlled to be 10-20 ℃ below zero.
Wherein the wall-scraping type hollow plate cooling continuous crystallizer inputs and outputs freezing circulating water through a refrigerator, and the temperature of the freezing circulating water is 5-40 ℃ below zero.
Example 2
A continuous crystallization process of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method comprises the following steps: the method comprises the following steps:
(1) opening a feeding valve of the tube type heat exchanger, starting a feeding pump, and feeding the titanium liquid with the temperature of 53-65 ℃ into the tube type heat exchanger;
(2) pre-cooling the titanium liquid to 38-45 ℃ in a shell and tube heat exchanger;
(3) when the temperature of the titanium liquid in the shell and tube heat exchanger reaches 38-45 ℃, the titanium liquid enters an elevated tank through a conveying pipeline and is continuously metered and enters a scraped-wall hollow sheet cooling continuous crystallizer;
(4) and starting a cooling water refrigerator, opening a cooling water regulating valve, and pumping circulating cooling water into the wall scraping type hollow plate cooling continuous crystallizer, wherein the temperature is controlled to be 10-15 ℃.
(5) Under the continuous spiral pushing of the scraped-wall hollow slab cooling continuous crystallizer, the titanium liquid is cooled by a cooling medium in the hollow slab in the flowing process, is continuously cooled to 12-13 ℃, and continuously flows into a titanium liquid storage tank in the next process through a discharge port;
in the process production, the size of ferrous sulfate crystal particles is adjusted by controlling the spiral rotating speed of a crystallizer, wherein the spiral rotating speed is 20-30 rpm/min.
Wherein the temperature of the circulating cooling water of the shell and tube heat exchanger is controlled to be 25-35 ℃.
Wherein the temperature of the cooling medium of the wall scraping type hollow plate cooling continuous crystallizer is controlled to be 10-20 ℃ below zero.
Wherein the wall-scraping type hollow plate cooling continuous crystallizer inputs and outputs freezing circulating water through a refrigerator, and the temperature of the freezing circulating water is 5-40 ℃ below zero.
Comparative example 1 vacuum crystallization process:
the existing vacuum crystallization process comprises the following steps:
1) opening a feed valve of the vacuum crystallization tank, starting a feed pump, and sending the precipitated titanium liquid with the temperature of 45-55 ℃ into the vacuum crystallization tank;
2) after feeding for 5 minutes, starting the stirrer for stirring, and allowing the titanium liquid to stay in the vacuum crystallization tank for 120-130 min;
3) when the titanium liquid flow meter is accumulated to reach the set volume of the crystallization tank, stopping feeding, and closing a feeding valve of the crystallization tank;
4) starting a water ring vacuum pump, opening a cooling water regulating valve, and pumping circulating cooling water into a vacuum crystallization tank;
5) when the absolute pressure meets the requirement of vacuum degree, a condenser and an ejector are started, when the temperature of the titanium liquid reaches 40 ℃, an ejector steam valve is started, the ejector steam valve is arranged on a steam pipeline connected with the ejector, when the temperature reaches 34-38 ℃, a vacuum crystallization tank feeding valve is opened, and 3-6 m of titanium liquid is pumped into the vacuum crystallization tank3Precipitating titanium liquid, closing a feed valve, opening a condenser and an ejector, automatically adjusting an ejector steam valve according to a preset program, wherein the steam pressure is less than or equal to 20KPa, the ejector steam valve is arranged on a steam pipeline connected with the ejector, and after the temperature is kept at 34-38 ℃ for 15-30 min, the temperature is reduced to the end point temperature of 12-15 ℃;
6) when the temperature of the titanium liquid reaches the set temperature, closing the steam valves of the ejectors in sequence;
7) closing the water ring vacuum pump and the condenser to cool and feed water;
8) and opening an emptying valve, reducing the pressure to about 30kPa, opening a discharge valve of the vacuum crystallization tank, discharging to a crystallized titanium liquid storage tank, and stopping the stirrer after discharging to obtain crystallized slurry.
Index detection and examination are respectively carried out in the examples provided by the invention, energy consumption and crystal particles are examined through the methods of examples 1 and 2 and the crystallization process of the comparative example, and the results are shown in table 1:
TABLE 1
According to pilot plant data, taking a certain plant in Zhejiang as an example, the vacuum crystallization process is carried out, and the energy consumption of the two processes is as follows:
according to the titanium white yield calculation of 10 ten thousand tons/year of the plant, only 15 ten thousand tons of steam are saved per year, and the cost can be saved by 3000 ten thousand yuan per year according to the price of 200 yuan/ton of steam. (the steam selling price is more than 200 yuan/ton at present). The electricity saving is about 150 ten thousand degrees each year.
At present, the domestic yield of titanium dioxide produced by a sulfuric acid process is over 300 million tons per year, and the benefit is 10 million yuan per year according to 300 million tons per year.
The particle size of ferrous sulfate particles in the continuous ferrous sulfate crystallization in the embodiment of the invention can be controlled, crystallization can be carried out according to the requirement, and the particle size obtained by the process method is more beneficial to the next process compared with the particle size obtained by a vacuum crystallization process.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (4)
1. A continuous crystallization process of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method is characterized in that: sending the titanium liquid into a tube type heat exchanger; pre-cooling the titanium liquid to 38-45 ℃ in a shell and tube heat exchanger; then the titanium liquid enters a head tank through a conveying pipeline and is continuously metered into a wall scraping type hollow plate cooling continuous crystallizer; the titanium liquid is continuously pushed by a screw in a wall-scraping type hollow slab cooling continuous crystallizer, is cooled by a cooling medium in a hollow slab, is continuously cooled to 12-14 ℃, and the titanium liquid containing ferrous sulfate crystals continuously flows into the next procedure through an outlet to realize the continuous crystallization of ferrous sulfate;
in the process production, the ferrous sulfate crystal particle size is controlled by regulating and controlling the spiral rotating speed of the wall scraping type hollow plate cooling continuous crystallizer, wherein the spiral rotating speed is 10-30 rpm.
2. The continuous crystallization process of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method according to claim 1, characterized in that: wherein the temperature of the circulating cooling water of the shell and tube heat exchanger is controlled to be 25-35 ℃.
3. The continuous crystallization process of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method according to claim 1, characterized in that: wherein the temperature of the cooling medium of the wall scraping type hollow plate cooling continuous crystallizer is controlled to be 10-20 ℃ below zero.
4. The continuous crystallization process of ferrous sulfate in the production of titanium dioxide by a sulfuric acid method according to claim 1, characterized in that: wherein the wall-scraping type hollow plate cooling continuous crystallizer inputs and outputs freezing circulating water through a refrigerator, and the temperature of the freezing circulating water is 5-40 ℃ below zero.
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| WO2022094780A1 (en) * | 2020-11-04 | 2022-05-12 | 成都千砺金科技创新有限公司 | Method for crystallizing ferrous sulfate heptahydrate during sulfuric-acid-method-based titanium dioxide production process |
| CN113044880B (en) * | 2021-03-23 | 2023-01-10 | 江苏勃仑化学有限公司 | Production process for increasing whiteness of titanium dioxide |
| CN115159566B (en) * | 2022-06-29 | 2024-12-06 | 杭州安永环保科技有限公司 | A method for integrating crystallization and concentration of black titanium liquid |
| CN115448375B (en) * | 2022-09-13 | 2023-11-07 | 攀钢集团攀枝花钢铁研究院有限公司 | Method and device for continuous crystallization of ferrous sulfate in titanium dioxide liquid using sulfuric acid method |
| CN115465897B (en) * | 2022-10-13 | 2025-02-07 | 攀枝花市海峰鑫化工有限公司 | A method for concentrating ferrous sulfate heptahydrate and titanium dioxide waste acid |
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