CN1266334C - Cotton pulp black liquor treating method nad electrolysis apparatus thereof - Google Patents
Cotton pulp black liquor treating method nad electrolysis apparatus thereof Download PDFInfo
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- CN1266334C CN1266334C CN 03134928 CN03134928A CN1266334C CN 1266334 C CN1266334 C CN 1266334C CN 03134928 CN03134928 CN 03134928 CN 03134928 A CN03134928 A CN 03134928A CN 1266334 C CN1266334 C CN 1266334C
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Abstract
The present invention relates to a method for disposing cotton pulp black liquor, which belongs to the technical field of sewage disposal, and the present invention is used for solving the problems that the discharge of terminal water can not reach the standard by recovering alkali and lignin in black liquor. The technical scheme comprises the following steps: a. filtration washing procedure: squeezing, filtering and washing cotton pulp and black liquor generated by steaming and pulping to obtain black liquor; b. a black liquor electrolyte procedure: after washing the squeezed and filtered original black liquor and the cotton pulp by one step, merging thick black liquor obtained by squeeze and filtration into anolyte, using clear water or very diluted alkali solutions as catholyte, introducing the anolyte and the catholyte into an electrolytic device to carry out electrolyte, recovering hydrogen gas by a cathode, and returning the alkali solutions to a pulping and alkali confecting procedure. The present invention disposes all cotton pulp black liquor, and reaches the standard of discharge. Alkali recovery rate is higher than the traditional method, the recovered hydrogen gas and lignin can be incinerated, and recycling heat energy can be further developed and utilized to obtain new economic benefit.
Description
Technical field
The present invention relates to a kind of processing method of black liquor, particularly the processing method of the black liquor of giving birth in the alkaline process pulp-making of cotton linter process belongs to technical field of sewage.
Background technology
Pulp-making of cotton linter is one of important channel that obtains the high-quality artificial fibre.The soda pulping process technologies that adopt in the paper industry, pulp-making of cotton linter also adopts soda pulping process technology more.No matter be that wood pulp, straw pulp or cotton pulp all can produce a large amount of black liquor in digestion process, contain organic substance such as lignin, hemicellulose, fiber degradation product in the black liquor, also contain inorganic substances such as various sodium salt, free NaOH etc.Black liquor is alkalescence, and the pH value is about 9～14, handles arbitrarily discharging as not adding, and can cause serious environmental to pollute, and also can cause the raising of production cost because alkali lye runs off simultaneously.Up to now, both at home and abroad comparative maturity and industrialized already black liquor processing method are black liquor vaporizing burning causticizing process, and the method is suitable for wood pulp, straw pulp, and in the cotton pulp since content of lignin far below wood pulp, straw pulp, and alkali content is high, uses said method obviously improper.At present, have lignin acidizing separation to add biochemical treatment process for the processing method of cotton pulp black liquor, chemical precipitation, coagulation add biochemical treatment process or the like.These methods are still not mature enough at aspects such as technology, equipment, technology, production costs, will add acid during as lignin acidizing separation in a large number, and the sedimentation and filtration process is serious to equipment corrosion, and the acid solution that filters out need be handled again, and technological process is long, alkali can not reclaim.At present, the cotton pulp black liquor of most of manufacturer can not be realized real qualified discharge, causes environmental pollution.Therefore, the new technology of the processing cotton pulp black liquor of exploitation practicality is crucial and has realistic meaning.
Summary of the invention
Problem to be solved by this invention is to overcome the defective of existing treatment technology and a kind of processing method that can fully reclaim the cotton pulp black liquor of alkali in the cotton pulp black liquor and lignin, realization terminal qualified discharge is provided.
Another problem to be solved of the present invention provides the used electrolysis unit of this processing method.
Problem of the present invention is solved by following technical scheme:
A kind of processing method of cotton pulp black liquor, it comprises following operation:
A. filter and cleaning process
Cotton pulp and black liquor that pulping by cooking is produced push, filter, wash, and obtain black liquor; Filtering, extrusion process, what squeeze out is raw black liquid;
Described washing procedure adopts three washings:
Cotton pulp after the extruding is carried out the washing first time, and washing back press filtration goes out concentrated black liquid;
Cotton pulp after the washing is for the first time carried out the washing second time, and washing back press filtration goes out rare black liquor;
Cotton pulp after the washing is for the second time washed for the third time, and washing back press filtration goes out extremely rare black liquor;
In above-mentioned steps, what cotton pulp carried out washing use for the first time is that last time cotton pulp carried out rare black liquor that the second time, filtration washing went out; Cotton pulp carries out that washing for the second time uses is that last time cotton pulp carried out extremely rare black liquor that filtration washing for the third time goes out; What cotton pulp washed use for the third time is clear water;
B. black liquor electrowinning process
The raw black liquid that the cotton pulp press filtration is gone out and the concentrated black liquid of cotton pulp press filtration behind once washing merge as anolyte, with clear water or extremely rare aqueous slkali as catholyte, introduce respectively carry out electrolysis in the electrolysis unit after, negative electrode recover hydrogen and aqueous slkali are recycled to aqueous slkali slurrying then and join the alkali operation.
The processing method of above-mentioned cotton pulp black liquor, after described black liquor electrowinning process, set up coagulation, solid-liquid separation process, this operation with electrolysis after anode generation partial oxidation, pH value be neutral or acid black liquor, introduce in the reactor and add precipitating agent and coagulant, filter the reaction back, burn the air-dry back of filter cake, and filtrate is recycled to slurrying and joins the alkali operation.
The processing method of above-mentioned cotton pulp black liquor, electrolysis temperature is 30-95 ℃ in the described electrowinning process, current density is 100-1000A.m
-2, electrolysis time is 1～4 hour.
A kind of cotton pulp black liquor is handled electrolysis unit, described electrolytic cell is a diaphragm electrolytic cell, used barrier film 1 is asbestos diaphragm or bique barrier film or cation-exchange membrane, described electric tank cathode 2 adopts iron net, iron plate, stainless (steel) wire, corrosion resistant plate or scribbles the negative electrode of stainless steel active coating, and anode electrolytic cell 4 adopts iron plate, copper coin, graphite cake, TiO
2-RuO
2/ Ti or IrO-Ta
2O
5/ Ti plate.
Above-mentioned cotton pulp black liquor is handled electrolysis unit, is parallel connection, series connection or series-parallel connection between described each electrolytic cell, and the bottom of electrolyzer anode chamber and cathode chamber is provided with inlet, and top is provided with liquid outlet.
The present invention compares with existing cotton pulp black liquor processing method has following advantage:
1. can come out black liquid extraction in the cotton pulp to greatest extent by the press filtration of washing several times, thereby residual black liquor is few when making thick slurry enter subsequent processing, makes the discharging of terminal water up to standard fully to cotton pulp.
2. realized the partially recycled of alkali by the black liquor electrolysis.
3. the black liquor after the electrolysis can more easily be realized Separation of Solid and Liquid, filtrate recycle slurrying, and filter cake burns and reclaims heat energy, and all black liquor is handled.
4. alkali of Hui Shouing and hydrogen can be offset the expense of electric energy basically, and the heat energy that the burning lignin produces can further develop, and obtains new economic benefit.
Description of drawings
Fig. 1 is the electrolysis unit structural representation.
The specific embodiment
The invention will be further described below in conjunction with drawings and Examples.
The method of the invention is made up of the washing of cotton pulp press filtration, black liquor electrolysis, three master operations of black liquor precipitation coagulation Separation of Solid and Liquid.Wherein, the cotton pulp filter and cleaning process is the important step of administering black liquor pollution, will as far as possible the black liquor in the cotton pulp be cleaned in this link and extrude, and makes black liquor residual quantity pettiness in the thick slurry that enters next process, guarantees terminal water emission compliance.Cotton pulp after the boiling and black liquor are formed the outstanding absurd creature of liquid state system, and the black liquor major part is distributed in the space between the cotton pulp fiber, and small part is present in the lumen, extracts the abundant press filtration that black liquor need rely on external force.Three washing press filtration methods that the present invention adopts can make extraction rate of black liquor in the cotton pulp greater than 95%, the high recovery rate 80% that usefulness method occurs far away.In washing process, rare black liquor or extremely rare black liquor that once washing liquid, secondary washing liquid use washing and filtering last time to go out respectively, what this method can realize water source in the washing process recycles the pollution-free discharging.Press master can use equipment such as acroll press washer, net formula press master, vacuum press master.
Black liquor electrowinning process of the present invention is the key link that reclaims alkali in the black liquor.The raw black liquid of press filtration and the concentrated black liquid of once washing merge the anode that enters electrolytic cell, and the negative electrode of electrolytic cell is water or extremely rare alkali lye (pH value 7.5～8).70～80 ℃ of preferred electrolysis temperatures, preferred current density 400～600A.m
-2, electrolysis time 1～3 hour.Negative electrode recover hydrogen in the electrolytic process, the electrolysis negative electrode alkali lye enrichment that finishes reclaims most of NaOH, and this aqueous slkali promptly can be used as the usefulness that alkali is joined in next slurrying.Oxidation reaction takes place in the anode black liquor after electrolysis, the pH value of black liquor reduces to 5～6, is introduced into and enters next step in the reactor.Diaphragm for electrolytic cell preferred cationic exchange membrane in this step, the preferred stainless (steel) wire of negative electrode, plate or stainless steel active coating electrode, anode preferably are the electrode of matrix band catalyst coatings with the titanium.Accompanying drawing 1 has provided the structural representation of electrolytic cell, and 1 is diaphragm for electrolytic cell in the drawings, and 2 is negative electrode, and 3 is cloudy chamber, and 4 is anode, and 5 is that positive chamber 6,7,8 is seal.Cloudy chamber and positive chamber respectively are provided with inlet and liquid outlet, can a plurality of electrolytic cell series, parallel or series-parallel connection be used by pipeline.
Coagulation of the present invention, solid-liquid separation process can extract lignin the black liquor after electrolysis.Be acid or neutral through the black liquor after the electrolysis, add small amount of precipitate agent and coagulant and can easier be settled out lignin, hemicellulose to handle a little, realize Separation of Solid and Liquid.The air-dry back of solid filter cake is burned and is reclaimed heat energy, and COD content degraded about 70% in the surplus liquid can be as in the slurrying dosing next time.So far, the whole processing and utilizing of cotton pulp black liquor.
Under the laboratory implementation of processing method of the present invention for example:
With volume is that cotton pulp is produced in 5 liters rotary spherical digester boiling.Add the air-dry cotton linter of 500 grams in the rotary spherical digester, amount to the over dry cotton linter 450 grams, NaOH 120 grams, 2700 milliliters in clear water.Be heated to 180 ℃, be incubated 330 minutes, naturally cool to about 50 ℃, take out the mixture of cotton pulp and black liquor, 3270 grams of weighing.With the manual press filtration of polyester filter screen, extrude 1800 milliliters of raw black liquids, add 1400 milliliters of hot water, carry out once washing.Fully mixing washing back press filtration goes out 1400 milliliters of dense nights, adds hot water again and carries out secondary washing for 1400 milliliters.Fully mixing washing back press filtration goes out 1400 milliliters of rare black liquor, adds 1400 milliliters of hot water for the third time and carries out three washings.Fully mixing washing back press filtration goes out 1400 milliliters of extremely rare nights.Be thick slurry through three washing gained slurries, 332 grams of weighing after the oven dry.Amount to merge 1400 milliliters of dense nights of leaching behind 1800 milliliters of raw black liquids and the once washing to 3200 milliliters, enter anode electrolytic cell, negative electrode adds 1000 milliliters in water, at 60 ℃, current density 400A.m
-2Electrolysis finished in 2.9 hours under the condition.Negative electrode residue 700 milliliters of aqueous slkalis (evaporating 300 milliliters), the dense 2.25mol.L of alkali
-1, reclaim alkali 63 grams.2800 milliliters of anolyte residues add the CaO14 gram, FeCl
3Gram reacts after 20 minutes and filters, and gets 1950 milliliters of filtrates.Filter cake is dried 86 grams of weighing.
Make second ball slurry, the air-dry cotton linter of 500 grams, adds 50 milliliters in water, adds alkali 57 grams, the identical boiling with first ball of temperature and time 1950 milliliters of anode filtrates, catholyte 700 milliliters (containing alkali 63 grams).Take out cotton pulp and black liquor mixture after the boiling, 3272 grams of weighing, basic identical with first ball.With the manual press filtration of polyester filter screen, extrude 1800 milliliters of raw black liquids.The rare black liquor that filters out with the secondary pulp washing of first ball carries out washing first time to second ball slurry then, and washing afterwards, press filtration goes out 1400 milliliters of concentrated black liquids.The extremely rare black liquor that goes out with three washing and filterings of first ball carries out secondary washing to second ball slurry, washes the back press filtration and goes out 1400 milliliters of rare black liquor.With 1400 milliliters of hot water second ball slurry is carried out three washings at last, wash the back press filtration and go out 1400 milliliters of extremely rare black liquor.Gained is slightly starched and is dried 342 grams of weighing.The raw black liquid, the concentrated black liquid that merge the second ball slurrying gained amount to 3200 milliliters and carry out electrolysis, and electrolytic condition is identical with last time, reclaim alkali 66 grams.
Make the 3rd ball slurry, the air-dry cotton linter of 500 grams, the anode filtrate of electrolysis for the second time adds that catholyte adds low amounts of water totally 2700 milliliters of liquid again, replenishes alkali to total amount 120 grams.With the temperature identical, time boiling with first ball.The washing methods of slurry is identical with second ball slurry.Gained is slightly starched and is dried 343 grams of weighing, and electrolyte reclaims 68 grams.
Continuous slurrying to the 7 balls as stated above, the thick slurry of every ball is basicly stable at 345 grams, and alkali reclaims and is stabilized in about 70 grams.The overall recovery of alkali is near 60%.Calculating electrolysis energy consumption by the alkali yield is about 4.5KWh/Kg.
The said precipitating agent of the present invention can adopt calcium hydroxide or calcium oxide, and coagulant can use aluminium chloride or iron chloride.
Claims (5)
1. the processing method of a cotton pulp black liquor, it is characterized in that: it comprises following operation:
A. filter and cleaning process
Cotton pulp and black liquor that pulping by cooking is produced push, filter, wash, and obtain black liquor; Filtering, extrusion process, what squeeze out is raw black liquid;
Described washing procedure adopts three washings:
Cotton pulp after the extruding is carried out the washing first time, and washing back press filtration goes out concentrated black liquid;
Cotton pulp after the washing is for the first time carried out the washing second time, and washing back press filtration goes out rare black liquor;
Cotton pulp after the washing is for the second time washed for the third time, and washing back press filtration goes out extremely rare black liquor;
In above-mentioned steps, what cotton pulp carried out washing use for the first time is that last time cotton pulp carried out rare black liquor that the second time, filtration washing went out; Cotton pulp carries out that washing for the second time uses is that last time cotton pulp carried out extremely rare black liquor that filtration washing for the third time goes out; What cotton pulp washed use for the third time is clear water;
B. black liquor electrowinning process
The raw black liquid that the cotton pulp press filtration is gone out and the concentrated black liquid of cotton pulp press filtration behind once washing merge as anolyte, with clear water or extremely rare aqueous slkali as catholyte, introduce respectively carry out electrolysis in the electrolysis unit after, negative electrode recover hydrogen and aqueous slkali are recycled to aqueous slkali slurrying then and join the alkali operation.
2. the processing method of cotton pulp black liquor according to claim 1, it is characterized in that: after the black liquor electrowinning process, set up coagulation, solid-liquid separation process, this operation with electrolysis after anode generation partial oxidation, pH value be neutral or acid black liquor, introduce in the reactor and add precipitating agent and coagulant, filter the reaction back, burn the air-dry back of filter cake, and filtrate is recycled to slurrying and joins the alkali operation.
3. the processing method of cotton pulp black liquor according to claim 1 and 2, it is characterized in that: electrolysis temperature is 30-95 ℃ in the described electrowinning process, current density is 100-1000A.m
-2
4. a cotton pulp black liquor is handled electrolysis unit, it is characterized in that: described electrolytic cell is a diaphragm electrolytic cell, used barrier film (1) is asbestos diaphragm or bique barrier film or cation-exchange membrane, described electric tank cathode (2) adopts iron net, iron plate, stainless (steel) wire, corrosion resistant plate or scribbles the negative electrode of stainless steel active coating, and anode electrolytic cell (4) adopts iron plate, copper coin, graphite cake, TiO
2-RuO
2/ Ti or IrO-Ta
2O
5/ Ti plate.
5. cotton pulp black liquor according to claim 4 is handled electrolysis unit, it is characterized in that: be parallel connection, series connection or series-parallel connection between described each electrolytic cell, the bottom of electrolyzer anode chamber and cathode chamber is provided with inlet, and top is provided with liquid outlet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03134928 CN1266334C (en) | 2003-09-30 | 2003-09-30 | Cotton pulp black liquor treating method nad electrolysis apparatus thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03134928 CN1266334C (en) | 2003-09-30 | 2003-09-30 | Cotton pulp black liquor treating method nad electrolysis apparatus thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1528976A CN1528976A (en) | 2004-09-15 |
| CN1266334C true CN1266334C (en) | 2006-07-26 |
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ID=34286219
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 03134928 Expired - Fee Related CN1266334C (en) | 2003-09-30 | 2003-09-30 | Cotton pulp black liquor treating method nad electrolysis apparatus thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102277591B (en) * | 2011-08-02 | 2014-03-05 | 北京化工大学 | Method for electrochemically degrading lignin |
| CN107986492A (en) * | 2017-12-01 | 2018-05-04 | 东华大学 | A kind of method that cotton pulp black liquor out-phase class Fenton oxidation processing improves biodegradability |
| CN113563605A (en) * | 2021-08-07 | 2021-10-29 | 木质素重庆科技有限公司 | Papermaking black liquor lignin separation and alkali recovery device and method |
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