CN214736971U

CN214736971U - White liquid production system and filtering mechanism, chemi-mechanical pulp papermaking system thereof

Info

Publication number: CN214736971U
Application number: CN202022599463.8U
Authority: CN
Inventors: 曹建初
Original assignee: Guangxi App Paper Co ltd
Current assignee: Guangxi App Paper Co ltd
Priority date: 2020-11-10
Filing date: 2020-11-10
Publication date: 2021-11-16
Anticipated expiration: 2030-11-10

Abstract

The application discloses white liquid production system and filtering mechanism, chemi-mechanical pulp papermaking system thereof. The filtering mechanism comprises a first clarifier, a filter and a plurality of pipelines; the first clarifier includes a clear liquid outlet; the filter comprises a white liquid outlet and a first channel, and the white liquid outlet is used for discharging filtered white liquid; the first channel is communicated with the clear liquid outlet through a pipeline; the filter further comprises a second channel, the first clarifier further comprising a lime mud inlet; the filtering mechanism also comprises a cache slot; wherein, the buffer tank is connected with the second channel and the lime mud inlet through pipelines respectively. Through the scheme, the suspension in the lower layer of the filter can be conveyed to the first clarifier for recycling, so that the liquid recovery efficiency of the liquid to be filtered can be improved.

Description

White liquid production system and filtering mechanism, chemi-mechanical pulp papermaking system thereof

Technical Field

The application belongs to the technical field of chemi-mechanical pulp papermaking, and particularly relates to a white liquid production system, a filtering mechanism of the white liquid production system and a chemi-mechanical pulp papermaking system.

Background

In the existing chemi-mechanical pulp papermaking process, pulp is usually washed, and the washing liquid after washing needs to be discharged after treatment so as to avoid the pollution problem. Wherein, after a series of treatments, the washing liquid, such as: evaporating, concentrating, burning, dissolving and causticizing to obtain mixed emulsion containing sodium hydroxide, sodium sulfide and calcium carbonate as main components.

In the prior art, after the mixed emulsion is filtered by a clarifier and a filter, white liquid and white mud are generated for recycling. Specifically, the supernatant in the clarifier is introduced into a filter for filtering, the supernatant in the filter can be discharged to form white liquid, and the lower-layer turbid liquid in the filter can be discharged for recovering white mud. However, the lower layer of turbid liquid in the filter also comprises white liquid which is not completely settled, which causes waste of the white liquid, namely, the alkali loss is increased, and further, the recovery rate of alkaline substances is low. In addition, the lower layer turbid liquid needs to be washed by a washer to obtain the white mud, the alkali content in the lower layer turbid liquid is increased, and the load of the white mud washer is also increased.

SUMMERY OF THE UTILITY MODEL

The application provides a white liquid production system and filtering mechanism, chemi-mechanical pulp papermaking system thereof to solve foretell technical problem.

In order to solve the technical problem, the application adopts a technical scheme that: there is provided a filter mechanism comprising:

a first clarifier comprising a clear liquid outlet;

the filter comprises a white liquid outlet and a first channel, and the white liquid outlet is used for discharging filtered white liquid; and

a plurality of tubes, wherein the first channel and the clear liquid outlet are in communication through the tubes; the filter further comprises a second channel, the first clarifier further comprising a lime mud inlet;

the filtering mechanism further comprises a cache slot;

wherein, the buffer tank passes through the pipeline and connects the second passageway with white mud entry respectively.

Optionally, a first liquid conveying device is arranged on the pipeline between the buffer tank and the lime mud inlet.

Optionally, a first switch is further disposed on the pipeline between the filter and the buffer tank, and the first switch is used for controlling on-off of the second channel.

Optionally, the device further comprises an intermediate tank, wherein the clear liquid outlet is communicated with the first channel through the pipeline.

Optionally, a second liquid conveying device is arranged between the middle tank and the filter, and the second liquid conveying device is used for guiding the liquid to be filtered in the middle tank into the filter.

Optionally, the first clarifier further comprises a white mud outlet, and the filtering mechanism further comprises a slag settling tank; the white mud outlet is communicated with the slag settling tank through the pipeline.

Optionally, comprising: a scrubber and a sediment filter;

the feed inlet of the washer is communicated with the sediment tank through the pipeline; the scrubber also comprises a dilute white liquid discharge port and a white mud discharge port; the dilute white liquid discharge port is used for discharging supernatant liquor of the washer, and the white mud discharge port is communicated with the sediment filter through the pipeline.

Optionally, a third liquid conveying device may be further disposed on the pipeline between the feed port of the scrubber and the slag settling tank.

In order to solve the technical problem, the application adopts a technical scheme that: there is provided a white liquor production system comprising a filter mechanism as hereinbefore described.

In order to solve the technical problem, the application adopts a technical scheme that: there is provided a chemi-mechanical pulp and paper making system comprising a white liquor production system as hereinbefore described.

The beneficial effect of this application is: this application embodiment is through setting up the second passageway on the filter, and is linked together the white mud entry of second passageway through buffer tank and first clarifier through the pipeline to can further carry out the circulating filtration processing in the first clarifier with the suspension of filter lower floor after discharging, can improve the liquid recovery efficiency in the white liquid that has the suspended particles, thereby can reduce the problem that leads to the white liquid waste when discharging the lower floor suspension of filter. In addition, the load of the lime mud scrubber can be reduced, and the reduction of the production efficiency of the causticizing station caused by the outflow of the white liquid mixed in the lime mud through the lime mud pipeline can be avoided. In addition, the waste of white liquor is avoided, so that the yield of the white liquor can be improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:

FIG. 1 is a schematic structural view of one embodiment of a filter mechanism provided herein;

fig. 2 is a schematic structural diagram of an embodiment of a white liquor production system provided by the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that if directional indications (such as up, down, left, right, front, and back … …) are referred to in the embodiments of the present application, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in the embodiments of the present application, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present application.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an embodiment of a filtering mechanism provided in the present application.

The filter mechanism 10 includes: a first clarifier 110, a filter 120, a buffer tank 130, and a plurality of pipes 101. Wherein the first clarifier 110 may comprise a receiving tank for receiving the suspension to be filtered. After the suspension to be filtered enters the accommodating groove, standing and precipitating can be carried out in the accommodating groove, so that solid suspended particles in the suspension to be filtered gradually precipitate to the lower layer of the accommodating groove, and clear liquid can be formed on the upper layer of the accommodating groove. The first clarifier 110 is also provided with a clear liquid outlet 111; the clear liquid outlet 111 may be communicated with the receiving tank, so that the clear liquid at the upper layer in the receiving tank may be discharged through the clear liquid outlet 111.

The filter 120 includes a white liquid outlet 121 and a first passage 122, the white liquid outlet 121 being for discharging filtered clear liquid; the first passage 122 and the clear liquid outlet 111 may communicate through the line 101. Accordingly, the clear liquid discharged from the clear liquid outlet 111 of the first clarifier 110 may be transferred to the filter 120 through the first passage 122 for filtration.

The filter 120 further comprises a second channel 123, the first clarifier 110 further comprises a lime mud inlet 112; the buffer tank 130 is connected to the second channel 123 and the lime mud inlet 112 through the pipe 101.

Therefore, the embodiment is characterized in that the second channel is arranged on the filter, and the second channel is communicated with the lime mud inlet of the first clarifier through the buffer tank by a pipeline, so that the suspension in the lower layer of the filter can be discharged and then further conveyed into the first clarifier for circular filtration treatment, the recovery efficiency of the liquid in the suspension with suspended particles can be improved, and the problem of liquid waste caused when the suspension in the lower layer of the filter is discharged can be reduced.

Alternatively, the filter 120 may be a pressure filter.

Specifically, in this embodiment, the filter sleeve 1201 is disposed in the filter 120, the first passage 122 may be connected to the middle of the filter 120 and communicated with the inner space of the filter 120, when the clear liquid enters the inner space of the filter 120 through the first passage 122, the inner space of the filter 120 may be gradually filled, and along with the increase of the liquid level of the clear liquid in the filter 120, the clear liquid may gradually contact and pass through the filter sleeve 1201, so that the clear liquid may be filtered. Thus, when the clear liquid passes through the filter sleeve 1201, it is shown that the filtration is complete and the desired liquid is formed.

That is, in this embodiment, the white liquid outlet 121 may be specifically opened at a position near the top of the filter 120. When the white liquid level on the upper side of the filter sleeve 1201 is continuously raised and reaches the position of the white liquid outlet 121, the white liquid on the upper side of the filter sleeve 1201 can be discharged from the filter 120 through the white liquid outlet 121 and then enter the subsequent processing treatment process. Specifically, the upper side of the filter casing 1201 can form the desired white liquid, and the lower side of the filter casing 1201 can form a suspension with suspended solid particles, wherein the suspended solid particles are sediment which cannot pass through the filter casing 1201. The second channel 123 may be in communication with a space below the filter sleeve 1201, so that the suspension below the filter sleeve 1201 may be discharged into the buffer tank 130 through the second channel 123, and the suspension entering the buffer tank 130 may be further transferred from the lime mud inlet 112 to the first clarifier 110 through the pipeline 101, so as to perform the circulating sedimentation filtration process.

Therefore, the suspension on the lower side of the filter sleeve 1201 in the filter 120 is discharged into the buffer tank 130, and then the suspension in the buffer tank 130 is conveyed into the first clarifier 110 from the white mud inlet 112, so that the suspension can be subjected to multiple times of circulating sedimentation filtration, the problem of white liquor waste can be avoided, and the yield of the white liquor can be improved.

In this embodiment, the clear liquid outlet 111 may be disposed near the upper end of the first clarifier 110, and when the liquid level in the first clarifier 110 reaches the clear liquid outlet 111, the clear liquid on the upper layer of the first clarifier 110 may flow out from the clear liquid outlet 111 and be further transmitted to the filter 120 through the pipeline 101.

Alternatively, in other embodiments, a liquid pump may be provided, the liquid pump line 101 of which may extend to a predetermined height of the first clarifier 110, and by means of which the clear liquid in the first clarifier 110 above the predetermined height may be pumped and transferred via the line 101 to the filter 120.

Referring to fig. 1, in the present embodiment, a first liquid delivery device 141 is disposed on the pipeline 101 between the buffer tank 130 and the lime mud inlet 112. The first liquid feeding means 141 may draw the suspension from the buffer tank 130 and feed the suspension to the first clarifier 110 through the lime mud inlet 112. The first liquid delivery device 141 aims to increase the power for delivering the buffer liquid in the buffer tank 130 to the lime mud inlet 112, so that the delivery of the buffer liquid is smoother. It will be appreciated that the first fluid delivery device 141 may be a fluid pump.

In this embodiment, a first switch 131 is further disposed on the pipeline 101 between the filter 120 and the buffer tank 130, and the first switch 131 is used for controlling the on/off of the second channel 123. When the filtration in the filter 120 is completed for a preset time so that the suspension on the lower side of the filter sleeve 1201 reaches a certain concentration, the first switch 131 may be turned on, so that the suspension on the lower side of the filter sleeve 1201 is discharged through the second channel 123 and into the buffer tank 130 through the pipeline 101; the clear liquid can be further transported through the first passage 122 into the middle filter 120, and after a certain amount of suspension has been discharged, the first switch 131 can be closed, so that the filtering operation can be further continued. The advantage of this scheme lies in, can then open first switch 131 and carry out flowing back once through setting up certain flowing back time at the time of filtering operation at every interval this flowing back time to can avoid appearing the concentration of the suspension of filter sleeve 1201 downside too high and lead to the filter sleeve 1201 to change the problem that the frequency is high. The liquid discharge time can be set according to actual conditions, and is not limited herein.

The first switch 131 may be a manual valve, and a person manually performs a switching operation to notify on/off of the pipeline 101 between the second channel 123 and the buffer tank 130; alternatively, the first switch 131 may be an automatic valve such as a solenoid valve, the first switch 131 may be automatically opened every preset draining time to transfer the lower suspension of the filter 120 into the buffer tank 130, and after the preset draining time is drained, the first switch 131 may be automatically closed to allow the filter 120 to continue the filtering operation.

Further, in the present embodiment, the filter mechanism 10 further includes an intermediate tank 150, wherein the intermediate tank 150 communicates the clear liquid outlet 111 with the first channel 122 through the pipeline 101. Specifically, the inner space of the intermediate tank 150 may communicate with the clear liquid outlet 111 through at least one pipe 101, and the inner space of the intermediate tank 150 may also communicate with the first passage 122 through at least one pipe 101. Therefore, the clear liquid discharged from the clear liquid outlet 111 can be transferred to the intermediate tank 150 through the pipe 101, and the clear liquid in the intermediate tank 150 can be further transferred to the filter 120 through the pipe 101 and the first channel 122.

A second liquid delivery device 142 may be further disposed on the pipeline 101 between the intermediate tank 150 and the first passage 122, and the second liquid delivery device 142 may draw out the clear liquid in the intermediate tank 150 and deliver the clear liquid to the filter 120 for filtering. The second liquid delivery device 142 is used to increase the power for delivering the buffer liquid in the intermediate tank 150 to the first channel 122, so that the delivery of the buffer liquid is smoother. Similarly, the second liquid delivery device 142 may be a liquid pump.

Please further refer to fig. 1. In this embodiment, the filtering mechanism 10 of the present application further includes a sediment treatment mechanism. The sludge treatment mechanism may be used to collect the bottom sediment in the first clarifier 110.

Specifically, the sludge treatment mechanism includes a sludge tank 160.

The slag settling tank 160 can be communicated with the first clarifier 110 through a pipeline 101, wherein the first clarifier 110 can be further provided with a white mud outlet 113; the sludge tank 160 may be in communication with the white mud outlet 113 via a line 101 for receiving the sediment at the bottom of the first clarifier 110, i.e. the white mud clarified by the first clarifier 110 is discharged to the sludge tank 160. A pump may be disposed in the pipe 101 between the sludge tank 160 and the first clarifier 110, and the sediment at the bottom of the first clarifier 110 may be pumped out and transported into the sludge tank 160 by the pump.

Further, since the white mud can be recycled, in this embodiment, in order to facilitate the recycling of the white mud, the sludge treatment mechanism further includes a scrubber 170 and a sludge filter 180 to treat the initial white mud in the sludge tank 160 frequently. Specifically, the scrubber 170 is configured to receive the sediment in the sediment tank 160 and clean the sediment, for example, the sediment may be cleaned by injecting clean water, so that a suspension with a low concentration may be obtained. The scrubber 170 may also include a material inlet and a material outlet, and the material inlet of the scrubber 170 may be communicated with the sediment tank 160 through the pipeline 101. The outlets of the scrubber 170 may include a dilute white liquid outlet 171 and a white mud outlet 172. The dilute white liquid outlet 171 can discharge the supernatant in the scrubber 170; the lime mud outlet 172 may be in communication with the sediment filter 180 via a line 101 to deliver the lower layer of low concentration suspension to the sediment filter 180. Wherein, on the pipeline 101 between the feed inlet of the scrubber 170 and the sediment tank 160, a third liquid conveying device 143 can be further arranged, and the third liquid conveying device 143 can extract the suspension of the sediment in the sediment tank 160 and convey the suspension into the scrubber 170.

The sediment filter 180 is used for receiving the low-concentration suspension, and filtering the low-concentration suspension, and the solid suspension in the low-concentration suspension can be filtered out through the sediment filter 180. Wherein, the filtered fixed suspended matters can be recovered; after the fixed suspended matters are filtered out, a solution with low concentration can be obtained for subsequent use.

In this embodiment, the sediment filter 180 may be a pre-suspended filter, and the low-concentration suspension is filtered by the pre-suspended filter, so that the liquid content of the filtered fixed suspension is low, and the recovery effect of the white liquid can be improved. Alternatively, in other embodiments, the sediment filter 180 may be other filtering devices, and is not further limited herein.

On the other hand, this application still provides a white liquid production system. Please refer to fig. 2. Fig. 2 is a schematic structural diagram of an embodiment of a white liquor production system provided by the present application. The white liquor production system 20 of the present application is a system for treating a stock liquor, i.e. washing liquor (i.e. black liquor) of pulp.

The white liquor production system 20 of the present application comprises, among other things, the filtration means 10 and the raw liquor treatment means as described hereinbefore. The raw liquid treatment mechanism is connected with the filtering mechanism 10. The raw liquid treatment mechanism comprises a black liquid treatment unit and a green liquid treatment unit, and the original white liquid treated by the green liquid treatment unit flows into the filtering mechanism 10 to be filtered to form white liquid and white mud meeting preset conditions. The filter mechanism 10 may be configured to filter white liquid with suspended particles generated after the green liquid treatment unit. The filtering mechanism 10 provided by the scheme can improve the liquid recovery efficiency of the white liquid with suspended particles and can reduce the problem of alkali waste in the production process.

In particular, in the field of chemi-mechanical pulp papermaking, especially in the process of making pulp by using a sulfate method or a soda method, the washing liquid of the pulp is black liquor. The black liquor needs to be disposed of after treatment to avoid pollution problems. In this embodiment, the black liquor treatment unit includes an evaporation concentrator, a burner and a dissolving tank, and the black liquor passes through the evaporation concentrator and the burner in sequence, so as to evaporate and concentrate the black liquor first and then burn the black liquor. Wherein the heat generated by the combustion is recovered in the form of steam. Most inorganic matters in the black liquor become molten state in the combustion process, and the molten state substances are mixed and dissolved with water or dilute white liquor in a dissolving tank to form green liquor (green liquor). The green liquor is treated by a green liquor treatment unit and becomes original white liquor (white liquor) after clarification. The original white liquor is filtered by the filtering mechanism 10 to form white liquor and white mud which meet the preset conditions, wherein the white liquor can be used for preparing cooking liquor to prepare paper pulp. The white mud, namely the precipitated calcium carbonate after the white liquor is clarified, is sent to a white mud warehouse of a thermal power plant for storage and recycling.

In this embodiment, the green liquor treatment unit treats lime milk as causticizing. Specifically, the green liquor treatment unit includes a feed tank 210, a second clarifier 220, a water eliminator 230, and a causticizing mechanism 240. The feeding tank 210 comprises a containing tank for storing green liquor, the feeding tank 210 can also be communicated with the second clarifier 220 through a pipeline 101, and the second clarifier 220 can receive the green liquor in the feeding tank 210 so as to perform standing precipitation. The second clarifier 220 also includes a green liquor outlet, which may be used to discharge the supernatant in the second clarifier 220, and the green liquor outlet of the second clarifier 220 may be in communication with a slaker 230 via line 101.

The water eliminator 230 comprises a green liquid inlet, a lime inlet and a liquid outlet, wherein the green liquid inlet of the water eliminator 230 is communicated with the green liquid outlet of the second clarifier 220 through a pipeline 101 and is used for inputting green liquid into the water eliminator 230; the lime inlet is used for inputting lime emulsion into the water treatment machine 230, and the lime emulsion is mixed with the green liquor.

A feed inlet of the causticizing mechanism 240 is communicated with a liquid outlet of the water eliminator 230 through a pipeline 101; the mixed solution in the water slaker 230 further enters the causticizing mechanism 240 through the feeding port of the causticizing mechanism 240 to perform a causticizing reaction, and the mixed solution can form a mixed solution of white liquid and white mud through the causticizing reaction.

Wherein, in order to ensure the reaction rate of the causticization reaction, the green liquor output from the green liquor outlet of the second clarifier 220 can be heated. Specifically, a heating device 250 can be arranged on the pipeline 101 between the green liquor outlet of the second clarifier 220 and the green liquor inlet of the water eliminator 230 through the pipeline 101; the green liquor output from the green liquor outlet of the second clarifier 220 may flow through the heating device 250, be heated by the heating device 250, and then further enter the water eliminator 230.

After the causticization reaction is completed, the mixed solution of the white liquor and the white mud can be discharged through a discharge hole of the causticizing mechanism 240.

The discharge port of the causticizing mechanism 240 may be connected to a mixed solution inlet (not shown) provided on the first clarifier 110 of the filtering mechanism 10 through a pipeline 101, so that the mixed solution of the white liquid and the white mud may be conveyed into the first clarifier 110 for subsequent filtering treatment. The embodiment of the filter mechanism 10 of the present application, in which the specific filtering process is as described above, will not be described in detail herein.

The second clarifier 220 may further comprise a green mud outlet, wherein the sediment at the bottom of the second clarifier 220 may be discharged through the green mud outlet for subsequent recovery treatment, and similarly, the sediment at the bottom of the second clarifier 220 may be washed and filtered by using the sediment treatment mechanism as described above, so as to recover the sediment at the bottom of the second clarifier 220, thereby obtaining green mud.

In yet another aspect, the present application further provides a chemi-mechanical pulp and paper making system. Wherein the chemi-mechanical pulp and paper making system comprises a pulp washing mechanism and a white liquor production system 20 as described hereinbefore.

Wherein, the pulp washing mechanism can be used for washing the pulp, and the liquid outlet of the pulp washing mechanism can discharge the washing liquid of the pulp, and the washing liquid is the black liquor as described above. The liquid outlet of the pulp washing mechanism can be communicated with the feed inlet of the black liquor treatment unit of the white liquor production system 20, and the black liquor is introduced into the black liquor treatment unit for treatment, so that green liquor can be obtained; the green liquor outlet of the black liquor treatment unit may be in communication with the feed tank 210 of the green liquor treatment unit of the white liquor production system 20, so that the formed green liquor may be transported into the feed tank 210 for storage. The initial white liquor treated by the green liquor treatment unit is filtered by the filtering mechanism 10 to form white liquor and white mud meeting preset conditions. The white liquor can be used for preparing the cooking liquor to prepare paper pulp. The white mud can be recycled.

In summary, those skilled in the art can easily understand that the beneficial effects of the present application are: through set up the second passageway on the filter, and be linked together the white mud entry of second passageway through buffer tank and first clarifier through the pipeline to can further carry out the circulation filtration processing in the first clarifier with the suspension of filter lower floor after discharging, can improve the liquid recovery efficiency in the white liquid that has the suspended particles, thereby can reduce the problem that leads to the white liquid waste when discharging the lower floor suspension of filter. In addition, the load of the lime mud scrubber can be reduced, and the reduction of the production efficiency of the causticizing station caused by the outflow of the white liquid mixed in the lime mud through the lime mud pipeline can be avoided. In addition, the waste of white liquor is avoided, so that the yield of the white liquor can be improved.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.

Claims

1. A filter mechanism comprising:

a first clarifier comprising a clear liquid outlet;

a plurality of tubes, wherein the first channel and the clear liquid outlet are in communication through the tubes; characterized in that the filter further comprises a second channel, the first clarifier further comprising a lime mud inlet;

the filtering mechanism further comprises a cache slot;

2. A filter mechanism according to claim 1, wherein a first liquid delivery means is provided in the conduit between the buffer tank and the lime mud inlet.

3. The filter mechanism of claim 2,

and a first switch is further arranged on the pipeline between the filter and the cache groove and used for controlling the on-off of the second channel.

4. The filter mechanism of claim 1, further comprising an intermediate tank communicating the clear liquid outlet with the first channel via the conduit.

5. The filter mechanism of claim 4,

a second liquid conveying device is arranged between the middle groove and the first channel and is used for guiding the liquid to be filtered in the middle groove into the filter.

6. The filter mechanism of claim 1, wherein the first clarifier further comprises a lime mud outlet, the filter mechanism further comprising a sludge chute; the white mud outlet is communicated with the slag settling tank through the pipeline.

7. The filter mechanism of claim 6, further comprising a scrubber and a sediment filter;

8. A filter mechanism according to claim 7, wherein a third liquid delivery means is provided in the conduit between the washer inlet and the grit chamber.

9. A white liquor production system comprising a stock solution treatment means, characterized in that it further comprises a filter means according to any one of claims 1 to 8, said stock solution treatment means being connected to said filter means.

10. A chemi-mechanical pulp and paper making system comprising the white liquor production system of claim 9.