Titanium dioxide slurry stepped concentration washing device

Abstract

The utility model discloses a titanium dioxide slurry cascade concentrating and washing device, which comprises a slurry washing unit, which sequentially comprises a slurry washing tank and a primary membrane mechanism; the slurry concentration unit sequentially comprises a slurry concentration tank and a secondary membrane mechanism; the low-salt water recovery unit sequentially comprises a reverse osmosis mechanism and a low-salt water recovery tank II; the slurry concentration unit is connected to the downstream of the slurry washing tank, the low-salt water recovery unit is connected to the downstream of the primary membrane mechanism, and the low-salt water recovery tank II is also connected to the downstream of the secondary membrane mechanism; and the secondary membrane mechanism is a rotary membrane device provided with a recoil mechanism. The scheme has the beneficial effects that the concentration efficiency is high, the concentration membrane flux attenuation is reduced, the service life of the membrane is prolonged, the process can be simplified, the water resource is saved, the energy consumption is reduced, low-salt water discharged by washing and concentration is subjected to gradient collection and cyclic utilization, and both economic benefits and environmental benefits are considered.

Description

TECHNICAL FIELD

[0001] The utility model relates to the production field of titanium dioxide, and specifically relates to a titanium dioxide slurry step-by-step concentration and washing device. BACKGROUND

[0002] Synthetic fibers have the characteristics of structural regularity, high crystallinity, orientation and smooth surface, and are prone to mirror reflection, resulting in strong fiber luster, so different refractive extinction agents need to be added to reduce the fiber luster. Titanium dioxide is the most common fiber extinction agent at present due to its high refractive index, good dispersibility, safety, non-toxicity and low price, and is widely used in polyester, nylon and cation production processes. The preparation of traditional titanium dioxide extinction agent needs to go through processes such as grinding, inorganic coating, washing, concentration and drying into powder, and the product is supplied in the form of powder, and the downstream manufacturers need to add water to prepare slurry before use, which increases the cost and is complicated. To solve this problem, concentration-adjustable titanium dioxide extinction agent slurry products appear on the market. To prepare conventional high-concentration titanium dioxide slurry, if traditional concentration methods such as heating concentration or reduced pressure concentration are used, there are problems such as high energy consumption, slow concentration efficiency and serious waste of water resources; if a membrane filtration device is used for pressure concentration, there are problems such as the influence of high-pressure environment on the service life of the membrane device and the recovery of membrane flux.

[0003] Chinese patent document CN101080263A disclosed on November 28, 2007, "Improved method and apparatus for concentrating slurry", the applicant introduced that the improved filter set includes a series of parallel arranged filter discs and shunt discs. The invention improves the existing filter set by using a basic whole welding to fix the shunt plate to the shunt disc. The invention also provides an improved method for pre-treating the filter set. The improved method is used to pre-treat and gradually prepare the filter set for producing the required titanium dioxide slurry. Further, the invention provides an improved process for preparing and transporting titanium dioxide slurry. Finally, the invention also provides a method for extending the service life of the filter set. This method for extending the service life of the filter set continuously monitors the flow rate and specific gravity of the fluid produced by the filter set and sends a signal to flush the filter set. This scheme improves the concentration efficiency of titanium dioxide and prolongs the service life of the filter set, but the concentration efficiency is still low for preparing high-concentration titanium dioxide slurry.

[0004] The Chinese patent document CN218290789U disclosed on January 13, 2023, a "titanium dioxide inorganic coated slurry washing and concentrating system", the applicant introduces that the scheme aims at the problem of difficult recovery of titanium dioxide in the suspension, and provides a titanium dioxide inorganic coated slurry washing and concentrating system, which comprises a centrifugal separation device, an ultrasonic device and a ceramic membrane filtration device. The titanium dioxide inorganic coated slurry is separated into light components and heavy components by the centrifugal separation device. The inlets of the ultrasonic device and the ceramic membrane filtration device are communicated with the centrifugal separation device, and the outlets are communicated with the finished product tank. The heavy components flow to the ultrasonic device, and a beater tank is arranged between the ultrasonic device and the finished product tank. The light components flow to the ceramic membrane filtration device, and an intermediate tank is arranged on the pipeline of the ceramic membrane filtration device. The communication valve between the ceramic membrane filtration device and the intermediate tank is a first three-way valve and a third three-way valve. The utility model uses centrifugal and ceramic membrane filter to distinguish the heavy and light components in the slurry, respectively washes and concentrates, avoids the defects of centrifugal and filtration, efficiently and quickly washes the titanium dioxide slurry, and removes inorganic salt ions. Although the concentration efficiency is improved to be used for preparing high-concentration titanium dioxide slurry, the primary membrane flux decays rapidly, the use period is shortened, and the membrane recovery process is complex.

[0005] Therefore, the main problem of the traditional scheme is that high concentration efficiency and reduced concentration membrane flux decay and prolonged service life of the membrane cannot be considered at the same time. In order to pursue high concentration efficiency, the membrane flux must be allowed to decay rapidly and the service life must be shortened. In order to pursue reduced flux decay and prolonged service life of the membrane, satisfactory concentration efficiency cannot be obtained. SUMMARY

[0006] Based on the above problems, the utility model provides a titanium dioxide slurry step-by-step concentrating and washing device, which can have high concentration efficiency, reduced concentration membrane flux decay, prolonged service life of the membrane, simplified process, saved water resources, reduced energy consumption, gradiently collected and circularly used low-salt water discharged in washing and concentrating, and considered economic benefit and environmental benefit.

[0007] In order to achieve the purpose of the application, the utility model adopts the following technical scheme: a titanium dioxide slurry step-by-step concentrating and washing device, comprising:

[0008] A slurry washing unit comprises a slurry washing tank and a primary membrane mechanism in sequence.

[0009] A slurry concentrating unit comprises a slurry concentrating tank and a secondary membrane mechanism in sequence.

[0010] A low-salt water recovery unit comprises a reverse osmosis mechanism and a low-salt water recovery tank II in sequence.

[0011] The slurry concentration unit is connected downstream of the slurry washing tank, the low-salinity water recovery unit is connected downstream of the primary membrane mechanism, and the low-salinity water recovery tank II is also connected downstream of the secondary membrane mechanism.

[0012] The secondary membrane mechanism is a rotary membrane device equipped with a backflush mechanism.

[0013] Preferably, the low-salinity water recovery unit further comprises a low-salinity water recovery tank I connected downstream of the primary membrane mechanism.

[0014] Preferably, an on-line conductivity meter is arranged between downstream of the primary membrane mechanism and upstream of the low-salinity water recovery tank I; an electrically-controlled valve is arranged upstream of the reverse osmosis mechanism and the low-salinity water recovery tank I; and the on-line conductivity meter signal is associated with the two electrically-controlled valves.

[0015] Preferably, a high-salinity water recovery tank is arranged immediately upstream of the reverse osmosis mechanism.

[0016] Preferably, a filter is connected between the slurry concentration tank and the secondary membrane mechanism.

[0017] Preferably, the backflush mechanism of the secondary membrane mechanism is an air backflush mechanism.

[0018] Preferably, a high-shear stirring mechanism is arranged on the slurry washing tank.

[0019] Preferably, a densimeter is arranged on the slurry washing tank.

[0020] Preferably, a liquid level meter is arranged on the slurry washing tank.

[0021] Preferably, a high-shear stirring mechanism is arranged on the slurry concentration tank.

[0022] Preferably, the system further comprises a finished slurry storage unit; and the finished slurry storage unit is connected downstream of the slurry concentration tank.

[0023] Preferably, the finished slurry storage unit comprises a finished slurry tank.

[0024] Preferably, a high-shear stirring mechanism is arranged on the finished slurry tank.

[0025] Preferably, the conductivity of the water produced by the reverse osmosis mechanism is less than or equal to 20 us / cm.

[0026] The present application has the following advantages:

[0027] (1) The high-concentration titanium dioxide slurry with adjustable concentration can be washed and concentrated, the process of drying and powdering in the traditional titanium dioxide lightening agent production is simplified, water consumption and energy consumption are saved, and the downstream manufacturers can directly use the product, thereby reducing the process equipment and water consumption cost of the downstream manufacturers.

[0028] (2) The filtrate concentrated by washing is gradiently recycled, water resources are fully utilized, waste water discharge is reduced, and economic benefits and environmental benefits are considered;

[0029] (3) The secondary membrane is adopted to concentrate the slurry after washing at a high concentration, the slurry at an adjustable concentration can be concentrated efficiently, the backflushing device is used to relieve flux attenuation in the use process of the secondary membrane, and the use cycle of the secondary membrane is prolonged; compared with a traditional negative pressure and temperature increasing concentration equipment, the secondary membrane has small occupied area and low energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a connection relationship schematic view of the utility model.

[0031] Among them: 1 slurry washing tank, 101 titanium dioxide slurry inlet, 102 pure water inlet, 103 low salt water inlet, 104 online density meter, 105 liquid level meter, 2 high shear stirring mechanism, 3 primary membrane mechanism, 301 primary membrane mechanism slurry inlet, 302 primary membrane mechanism slurry outlet, 303 high salt water filtrate outlet, 304 low salt water filtrate outlet, 305 online conductivity meter, 4 high salt water recovery tank, 5 reverse osmosis mechanism, 6 low salt water recovery tank I, 7 low salt water recovery tank II, 8 slurry concentration tank, 9 secondary membrane mechanism, 901 secondary membrane mechanism slurry inlet, 902 secondary membrane mechanism slurry outlet, 903 filtrate outlet, 10 filter, 11 finished slurry tank. DETAILED DESCRIPTION

[0032] The application will be further described below in combination with the drawings and specific embodiments.

[0033] Embodiment 1

[0034] Embodiment 1 is a titanium dioxide slurry step-by-step concentration and washing device, which is applied to a certain chemical fiber production enterprise. Figure 1 As shown in the figure, the titanium dioxide slurry step-by-step concentration and washing device of the embodiment mainly comprises a slurry washing unit, a slurry concentration unit and a low salt water recovery unit.

[0035] Among them, the slurry washing unit comprises a slurry washing tank 1 and a primary membrane mechanism 3. The slurry concentration unit comprises a slurry concentration tank 8 and a secondary membrane mechanism 9. The low salt water recovery unit comprises a reverse osmosis mechanism 5 and a low salt water recovery tank II 7.

[0036] The slurry washing tank 1 is used to contain the titanium dioxide slurry to be treated.

[0037] The primary membrane mechanism 3 is a ceramic membrane device, and a publicly traded product same as or similar to CN218290789U can be selected.

[0038] The slurry concentration tank 8 is used to store the titanium dioxide slurry after the first stage concentration.

[0039] The secondary membrane mechanism 9 is a rotating membrane device, and a publicly available product can also be selected. A reverse flushing mechanism is provided, and a similar combination can be seen in the disclosure of Chinese Patent Document CN110871033A. Those skilled in the art can also combine to form a device with the same technical effect according to actual design needs.

[0040] The reverse osmosis mechanism 5 is used to treat high-concentration brine. After reverse osmosis treatment, salt can be precipitated, and the concentration of the brine can be reduced. The reverse osmosis mechanism 5 uses a publicly available product commonly used in the water treatment field. During implementation, it is recommended to control the conductivity of the water produced by the reverse osmosis mechanism 5 to be less than or equal to 20 us / cm.

[0041] The low-salinity brine recovery tank II 7 is used to collect low-concentration brine obtained after treatment by the reverse osmosis mechanism 5.

[0042] The layout of each part of the device in this example is as follows:

[0043] The slurry washing tank 1 is located at the most upstream, and the downstream is divided into two branches, one of which is connected to the primary membrane mechanism 3, and the other is connected to the slurry concentration tank 8.

[0044] The downstream of the primary membrane mechanism 3 is also divided into two branches, one of which is returned to the slurry washing tank 1, and the other is directed to the low-salinity brine recovery unit.

[0045] The low-salinity brine recovery unit is in turn the reverse osmosis mechanism 5 and the low-salinity brine recovery tank II 7.

[0046] The downstream of the aforementioned slurry concentration tank 8 is directed to the secondary membrane mechanism 9, and the downstream of the secondary membrane mechanism 9 is also divided into two branches, one of which is connected to the low-salinity brine recovery tank II 7, and the other is returned to the slurry concentration tank 8.

[0047] The treatment process is as follows:

[0048] The titanium dioxide slurry to be treated is preloaded in the slurry washing tank 1, and then pumped to the primary membrane mechanism 3 through the primary membrane mechanism slurry inlet 301. The first-stage concentration is performed in the primary membrane mechanism 3. One branch of the downstream of the primary membrane mechanism 3 is the concentrated semi-finished titanium dioxide slurry, which is punched back into the slurry washing tank 1 through the primary membrane mechanism slurry outlet 302 for cyclic treatment until the semi-finished titanium dioxide slurry in the slurry washing tank 1 reaches the predetermined index parameters. The other branch is the brine precipitated in the primary membrane mechanism 3, which is sent to the reverse osmosis mechanism 5 through the high-salinity filtrate outlet 303 for treatment, and the low-concentration brine obtained after the salt is precipitated is directed to the low-salinity brine recovery tank II 7.

[0049] When the semi-finished titanium dioxide slurry in the slurry washing tank 1 reaches the predetermined index parameters, the semi-finished titanium dioxide slurry is pumped into the slurry concentration tank 8.

[0050] The slurry concentration tank 8 pumps the semi-finished titanium dioxide slurry to the secondary membrane mechanism 9 through the secondary membrane mechanism slurry inlet 901 for secondary concentration. Downstream of the secondary membrane mechanism 9, one branch of the concentrated semi-finished titanium dioxide slurry is pumped back to the slurry concentration tank 8 through the secondary membrane mechanism slurry outlet 902 for recycling until the titanium dioxide slurry in the slurry concentration tank 8 reaches the required concentration. The other branch is the concentrated brine in the secondary membrane mechanism 9, which is guided to the low-salinity brine recovery tank II 7 through the filtrate outlet 903. The low-salinity brine collected in the low-salinity brine recovery tank II 7 can be used after measurement and proportioning, which can reduce pollution emissions and save water.

[0051] This embodiment is the basic version of the scheme, and subsequent embodiments will be optimized on the basis of this embodiment.

[0052] Embodiment 2

[0053] Embodiment 2 is another titanium dioxide slurry step-by-step concentration and washing device. Referring to Figure 1 The embodiment adds a low-salinity brine recovery tank I 6 as part of the low-salinity brine recovery unit.

[0054] Specifically, the low-salinity brine recovery tank I 6 is arranged side by side with the reverse osmosis mechanism 5, both downstream of the primary membrane mechanism 3.

[0055] When the slurry washing tank 1 and the primary membrane mechanism 3 are circulated and concentrated for a period of time, the brine concentrated from the primary membrane mechanism 3 has a concentration lower than the design parameter, and the brine at this time can be directly used. Therefore, the low-concentration brine from the primary membrane mechanism 3 can be guided to the low-salinity brine recovery tank I 6 for collection to reduce water resource waste.

[0056] The same as embodiment 1.

[0057] Embodiment 3

[0058] Embodiment 3 is another titanium dioxide slurry step-by-step concentration and washing device. Referring to Figure 1 The embodiment sets a brine concentration detection and flow control mechanism downstream of the primary membrane mechanism 3.

[0059] The salt water concentration detection and flow direction control mechanism includes an on-line conductivity meter 305 close to the downstream of the first membrane mechanism 3, and downstream of the on-line conductivity meter 305, the flow is divided into two branches, one branch flows to the low-salt water recovery tank I6, and the other branch flows to the reverse osmosis mechanism 5. At the same time, electric control valves are arranged on the two branches. The on-line conductivity meter 305 can detect the concentration of the salt water in the pipeline at any time, and transmit the signal to the control center, such as PLC, etc., and the control center compares the real-time value with the preset value to determine whether the salt water in the pipeline is high-concentration salt water or low-concentration salt water; if it is high-concentration salt water, the signal controls the electric control valve on the branch where the reverse osmosis mechanism 5 is located to be opened, and the reverse osmosis is performed before collection; if it is low-concentration salt water, the signal controls the electric control valve on the branch where the low-salt water recovery tank I6 is located to be opened, and the low-salt water is directly collected into the low-salt water recovery tank I6.

[0060] The rest is the same as in Example 2.

[0061] Example 4

[0062] Example 4 is another kind of titanium dioxide slurry step-by-step concentration and washing device. Referring to Figure 1 , in this example, a high-salt water recovery tank 4 is additionally arranged in the low-salt water recovery unit, and the specific position is close to the upstream of the on-line conductivity meter 305 and the downstream of the electric control valve on the branch.

[0063] The rest is the same as in Example 3.

[0064] Example 5

[0065] Example 5 is another kind of titanium dioxide slurry step-by-step concentration and washing device. Referring to Figure 1 , in this example, a filter 10 is additionally arranged in the slurry washing unit, and the specific position is between the slurry concentration tank 8 and the second membrane mechanism 9.

[0066] The filter 10 is arranged to prevent the large particles from the slurry in the slurry concentration tank 8 from blocking the membrane circulation in the second membrane mechanism 9, thereby prolonging the service life of the membrane. The filter 10 can also use commercially available conventional types and specifications.

[0067] The rest is the same as in Example 4.

[0068] Example 6

[0069] Example 6 is another kind of titanium dioxide slurry step-by-step concentration and washing device. Referring to Figure 1 , in this example, the backflush mechanism on the second membrane mechanism 9 is defined as an air backflush mechanism. The impact force of the air backflush mechanism on the membrane is relatively gentle compared with the same volume and flow rate of water, and under the premise of ensuring the backflush effect, the air backflush can better prolong the service life of the membrane.

[0070] The rest is the same as in Example 5.

[0071] Example 7

[0072] Example 7 is another kind of step-by-step concentration and washing device for titanium dioxide slurry. Referring to Figure 1 As shown, in this example, a finished slurry storage unit is also included, which is a slurry finished product tank 11, and a pipeline is connected downstream of the slurry concentration tank 8 in parallel with the secondary membrane mechanism 9.

[0073] After the slurry is concentrated to the required concentration by the secondary membrane mechanism 9, the slurry concentration tank 8 can pump the finished titanium dioxide slurry into the slurry finished product tank 11 for production use or another filling and storage. The slurry concentration tank 8 can be emptied for the next round of washing and concentration.

[0074] The rest is the same as Example 6.

[0075] Example 8

[0076] Example 8 is another kind of step-by-step concentration and washing device for titanium dioxide slurry. Referring to Figure 1 As shown, in this example, high-shear stirring mechanisms are added to the slurry washing tank 1, the slurry concentration tank 8, and the slurry finished product tank 11 in order to stir evenly and avoid the titanium dioxide slurry from clumping and caking, which affects the washing and concentration effect and also affects the subsequent use.

[0077] The rest is the same as Example 7.

[0078] Example 9

[0079] Example 9 is another kind of step-by-step concentration and washing device for titanium dioxide slurry. Referring to Figure 1 As shown, in this example, a titanium dioxide slurry inlet 101, a pure water inlet 102, and a low-salt water inlet 103 are added above the slurry washing tank 1. The titanium dioxide slurry inlet 101 is used to add the titanium dioxide slurry to be treated into the slurry washing tank 1, the pure water inlet 102 is used to add pure water into the slurry washing tank 1, and the low-salt water inlet 103 is used to add low-concentration salt water into the slurry washing tank 1, such as the low-concentration salt water collected by the low-salt water recovery tank I6 in Example 2.

[0080] In specific settings, the titanium dioxide slurry inlet 101 and the pure water inlet 102 are introduced by different pipelines, and before entering the slurry washing tank 1, they are connected in parallel into the same pipeline, while the low-salt water pipeline is a separate pipeline that enters the slurry washing tank 1.

[0081] In this example, an online densitometer 104 and a liquid level meter 105 are also provided on the slurry washing tank 1 to measure the actual concentration and quality of the titanium dioxide slurry in the slurry washing tank 1.

[0082] The applicant makes a simple effect comparison. The traditional plate filter is used to concentrate and wash the titanium dioxide slurry. Since the filtrate contains a large amount of titanium dioxide, the filtrate drainage appears milky white, which is not conducive to the recycling of waste water and is easy to pollute the environment. In addition, the loss rate of titanium dioxide is large, about 3% to 10%, and the titanium dioxide slurry cannot be filtered and concentrated at a high concentration. After the concentration treatment of the present embodiment, only a small amount of ultra-high concentration brine is precipitated from the reverse osmosis mechanism 5. This part can be recycled in the factory. The low-concentration brine in the low-salt water recovery tank I 6 can be directly introduced into the slurry washing tank 1 for recycling. The low-concentration brine collected in the low-salt water recovery tank II 7 can also be used after measurement and proportioning. Therefore, almost no waste liquid is generated in the whole treatment process, and the economic benefit and environmental benefit are very high.

[0083] The remainder is the same as in Example 8.

[0084] In the above examples, appropriate valves, pumps, temperature controls, pressure controls and other components should be provided on the pipeline system at appropriate positions. This can be set by the person skilled in the art according to the actual needs and industry common sense, and will not be specifically shown in the figure and will not be described in detail herein.

[0085] In summary, the advantages of the present scheme are:

[0086] The titanium dioxide slurry after inorganic coating is washed and pre-concentrated by the first membrane mechanism. The uncoated inorganic salt ions in the titanium dioxide slurry are removed by washing to improve the dispersibility of titanium dioxide and reduce the influence of inorganic salt ions on fiber polymerization. Then the washed titanium dioxide slurry is pre-concentrated, and the low-salt water collected by washing and concentration is collected by gradient and recycled. The pre-concentrated slurry is further concentrated by the second membrane mechanism to become a titanium dioxide finished slurry with adjustable concentration. The low-salt water collected by concentration is recycled;

[0087] The discharge amount of the first membrane mechanism is controlled by adjusting the membrane flux of the discharge liquid to realize the low-concentration concentration of the titanium dioxide slurry. On the one hand, the pressure of the second membrane concentration in the subsequent process is reduced, and on the other hand, the flux decay of the first membrane is delayed, and the service life of the first membrane is improved. The filtrate with high concentration of ions of the washed slurry is collected into the high-salt water recovery tank, and the filtrate with low concentration of ions of the washed slurry is collected into the low-salt water recovery tank I to realize the collection of waste water with different ion concentrations;

[0088] By adjusting the discharge liquid membrane flux of the secondary membrane mechanism to control the drainage amount, high concentration regulation of the titanium dioxide slurry is realized, the titanium dioxide slurry with adjustable concentration can be prepared, directly supplied to the downstream use, and the process equipment and water consumption cost of the downstream manufacturer are reduced; the backflush mechanism and the flux recovery process of the secondary membrane mechanism delay the attenuation of the secondary membrane flux; meanwhile, the low-salinity water concentrated can be collected to the low-salinity water recovery tank II, and the low-salinity water can be recycled to the subsequent slurry washing, so that the water resources are fully utilized, and the wastewater treatment cost is reduced.

Claims

1. A slurry concentration cascade washing apparatus for titanium dioxide slurry, characterized by, The application relates to a slurry production system. The slurry production system comprises: a slurry washing unit sequentially comprising a slurry washing tank (1) and a primary membrane mechanism (3); a slurry concentration unit sequentially comprising a slurry concentration tank (8) and a secondary membrane mechanism (9); a low-salinity water recovery unit sequentially comprising a reverse osmosis mechanism (5) and a low-salinity water recovery tank II (7); the slurry concentration unit is connected downstream of the slurry washing tank (1), the low-salinity water recovery unit is connected downstream of the primary membrane mechanism (3), and the low-salinity water recovery tank II (7) is also connected downstream of the secondary membrane mechanism (9); 2. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 1, characterized in that the secondary membrane mechanism (9) is a rotary membrane device provided with a backflush mechanism.

3. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 2, characterized in that The low-salinity water recovery unit further comprises a low-salinity water recovery tank I (6) connected downstream of the primary membrane mechanism (3).

4. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 1 or 2 or 3, characterized in that An on-line conductivity meter (305) is arranged between the downstream of the primary membrane mechanism (3) and the upstream of the low-salinity water recovery tank I (6); electric control valves are arranged upstream of the reverse osmosis mechanism (5) and the low-salinity water recovery tank I (6); and the on-line conductivity meter (305) is signal-associated with the two electric control valves.

5. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 1 or 2 or 3, characterized in that A filter (10) is connected between the slurry concentration tank (8) and the secondary membrane mechanism (9).

6. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 1 or 2 or 3, characterized in that The backflush mechanism of the secondary membrane mechanism (9) is an air backflush mechanism.

7. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 1 or 2 or 3, characterized in that A high-shear stirring mechanism (2) is arranged on the slurry washing tank (1).

8. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 1 or 2 or 3, characterized in that A densimeter (104) is arranged on the slurry washing tank (1).

9. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 1 or 2 or 3, characterized in that A liquid level meter (105) is arranged on the slurry washing tank (1).

10. A device for stepwise concentration and washing of a titanium dioxide slurry according to claim 1 or 2 or 3, characterized in that The conductivity of the water produced by the reverse osmosis mechanism (5) is below 20 us / cm. The application further relates to a finished slurry storage unit; the finished slurry storage unit is connected downstream of the slurry concentration tank (8).

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