CN1285436A - Method and equipment for treating black liquor into boil solution - Google Patents
Method and equipment for treating black liquor into boil solution Download PDFInfo
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- CN1285436A CN1285436A CN 00129510 CN00129510A CN1285436A CN 1285436 A CN1285436 A CN 1285436A CN 00129510 CN00129510 CN 00129510 CN 00129510 A CN00129510 A CN 00129510A CN 1285436 A CN1285436 A CN 1285436A
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Abstract
The method for treating pulping black liquor and making one into cooking liquor to prevent black liquor pollution includes the following steps: 1. making solid-state substance in black liquor react with calcium ions being in lime, gypsum or calcium chloride to produce solid precipitate which is insoluble in water; 2. solid-liquid separation; 3. drying the above-mentioned solid precipitate and incinerating; and 4. supplementing alkali quantity in separated clear liquor, and making it into cooking liquor for reuse. Said invented method is simple in equipment, reliable, and easy to operate, etc.
Description
The present invention relates to black liquor of pulp making is processed into the method and apparatus of cooking liquor.More particularly, the present invention relates to black liquor and lime, gypsum or calcium chloride reaction that slurrying is produced, with the most of soluble solids in the calcium ion precipitation black liquor, after the Separation of Solid and Liquid, supply alkali number for the clear liquid of separating, remove the method and apparatus of slurrying again as cooking liquor with it.With the cooking liquor pulping by cooking that deals by the present invention, obtain the paper pulp of commercial pulp quality equally.
Process with the cellulose in the plant is separated is referred to as slurrying; The crude fibre of separating is referred to as slurry.Slurry is the raw material of papermaking and spinning artificial fibre.Industrial, with the plant of soda lye boiling rich cellulose, produce chemical pulp.The aqueous solution of caustic soda is called cooking liquor; The instantiation of rich cellulose plant has timber, bamboo wood, wheat straw, straw, bagasse, cotton linter, Chinese alpine rush, reed and awns bar etc.In digestion process, complicated chemical reaction takes place in alkali in the cooking liquor and plant tissue, and the result is: destroyed the structure of plant tissue, its non-cellulose composition is dissolved in the cooking liquor.After the boiling, cooking liquor becomes black, is to extrude the cellulosic slurry it from main component, and the liquid of extruding is called " black liquor "; To extrude with the black liquor that the low amounts of water pulp washing floods out again, also claim " black liquor "; Again the black liquor of extruding is combined, be called " the black liquor of extraction." process of this collection black liquor, be called " extraction black liquor ".In the black liquor that extracts, the organic matter beyond dewatering and the summation of inorganic matter are called " solid content ", and general solid content accounts for the black liquor about 12% of extraction.Solid content accounts for the percentage that removes the solid content starching in the black liquor after the boiling in the black liquor that extracts, and is called " extraction rate of black liquor." be the product of slurrying with the clean slurry of massive laundering again, black liquor is a refuse; The solid content in extracting black liquor when starching with massive laundering, is not distributed in the pulp washing water, becomes the part of middle section water.
Except that a large amount of water, the main organic principle of black liquor has lignin, polysaccharide and other boiling product on a small quantity; Inorganic constituents mainly is the sodium that exists with multi-form, and the inorganic impurity that brings of raw material.To straw pulping black liquor, the inorganic impurity attack that silicon content is high.
Industrial use evaporation burning method is handled pulp black liquor, and mature and reliable constitutes the part of traditional pulping process.This method is, after black liquor is concentrated with multi-effect evaporator, sprays into incinerator, burns organic matter, utilizes heat energy; Sodium in the black liquor is transformed into sodium carbonate, and it and inorganic impurity are stayed in the slag, use the water retting slag, and the solution that dissolves sodium carbonate claims " green liquor "; Again with green liquor with lime causticization after, Separation of Solid and Liquid, the soda bath that is commonly called as " white liquid " is used to prepare cooking liquor; " white clay " of precipitation is transformed into quick lime through calcining, in the reuse of causticization operation.To large-scale wood pulp factory, its caustic soda rate of recovery can reach more than 95%, and that reclaims alkali overbalances day-to-day operation expense and depreciation of equipment, does not have the black liquor pollution environment.
The shortcoming of this method is, process route is oversize, complicated operation, and equipment investment is too big.Another shortcoming is that evaporation capacity is too big.1 ton of slurry of every production produces the black liquor of 10 tons of extractions; Solid content is about 12% in the black liquor; The content that is sprayed onto the concentrated black liquor solid content in the incinerator is higher than 60%; Just, 1 ton of slurry of every production will evaporate about 8 tons of water.Produce the pulp mill of 30,000 tons of slurries per year, 100 tons in daily output slurry extracts 1000 tons of black liquor, evaporates about 800 tons of moisture every day.Also have, be ejected into the moisture in the concentrated black liquid in the incinerator, also will in incinerator, evaporate.In fact, this is the method that the moisture in the black liquor that will extract all evaporates.
China's timber resource shortage, straw pulp accounts for main flow, and middle small straw plant accounts for the main flow of straw pulp again.When applying mechanically this method straw pulping black liquor, meet difficulty.Be financial difficulty on the surface, this method equipment investment is too big, and to any enterprise, raising the funds all is difficulty.In fact, expose the other shortcoming of this method.Use the draft raw pulp, the silicone content in the black liquor exceeds an order of magnitude than timber black liquor, and lignin content is more much lower than pulp black liquor.Silicon and other impurity content height in the straw pulp black liquor, viscosity is big.Extract the black liquor operation and be difficult to accomplish, the recovery rate height, extracted amount is few; Extraction rate of black liquor is low, increases the processing load of middle section water; Extracted amount is many, increases the load of evaporation.
When evaporation and concentration, silicon and impurity are deposited on the tubulation wall and the heat transfer wooden partition of evaporimeter, influence heat transfer efficiency, even cause evaporimeter not work.Even taked to give the silica removal measure, the frequent parking of still having to removed the fouling of evaporimeter, improved operating cost.
In incinerator, the calorific value that concentrates straw pulp black liquor is lower than the wood pulp, and impurity is more than wood pulp, causes easily and burns instability.Or burn insufficiently, and or cause alkali loss when burning, make alkali recovery be lower than the burning pulp black liquor.The large-scale straw pulp black liquor firing method soda recovery unit of present operation, alkali recovery is far below pulp black liquor.Can the value that reclaim alkali offset with running cost and depreciation of equipment, and confirmation also needs to be in operation.
To middle-size and small-size straw pulp mill, apply mechanically this method and handle black liquor, reclaim the not nearly enough equipment depreciation of value and the daily expenditure of alkali, reduced economic benefit of enterprises significantly, even loss; Enterprise does not have enthusiasm.Therefore cause the process of administering the straw pulp black liquor pollution slow, black liquor continues contaminated environment.State Environmental Protection Administration and light industrial bureau be for protection broad masses of the people's fundamental interests, to serious pollution straw pulp mill, take time limit control, stop, close, also, the policy of commentaries on classics.
Need at reality, we have studied with chemical method black liquor have been transformed into the technology of cooking liquor, fundamentally eliminate black liquor pollution, do not damage the existing economic interests of straw pulp mill again.Therefore, the objective of the invention is to, provide a kind of black liquor of pulp making is processed into the cooking liquor that boiling is once more used, to prevent the method for black liquor pollution.Compare with traditional evaporation burning method, method provided by the invention, technology is reliable, equipment is simple, processing ease, the saving energy, small investment, effective.
Use method of the present invention, black liquor is processed into cooking liquor, the moisture of black liquor all need not be evaporated, save the energy; Water resource is saved in the reuse of part water.Do not need the evaporation and concentration black liquor, do not have the problem of silicon fouling.Organic matter in the black liquor precipitates into solid earlier, and drying incinerates again, and incinerator is simple, burns stable.
Another object of the present invention provides employed decanter type solid-liquid separation tank in the method for the present invention.
Method of the present invention is summarized as follows:
Black liquor of pulp making is processed into the cooking liquor that boiling is once more used, prevents the method for black liquor pollution, it is characterized in that comprising the steps:
(1) solid content and the calcium ion in lime, gypsum or the calcium chloride in the black liquor of pulp making are reacted, generate the water-insoluble solid precipitation;
(2) Separation of Solid and Liquid;
Burn the dry back of aqueous solid precipitation of (3) separating;
(4) after the clear liquid of separating is supplied alkali number, become the cooking liquor that boiling is once more used.
By method of the present invention, all black liquor that slurrying produces are all handled, make it be transformed into enough cooking liquors, this has just eliminated black liquor up hill and dale, has prevented black liquor pollution.
Solid content in the black liquor is, because the effect of alkali (NaOH) is dissolved from the raw material grass or is shed to organic matter and inorganic matter in the liquid.Its composition can't represent that its overwhelming majority can and be added to the calcium ion combination that lime, gypsum or calcium chloride in the black liquor dissociate out one by one with chemical formula accurately, generates the water-insoluble solid precipitation, and sodium ion simultaneously dissociates.Black liquor and lime reaction, the sodium ion that dissociates becomes NaOH; Black liquor and gypsum reaction, the sodium ion that dissociates out becomes sodium sulphate; Black liquor and calcium chloride reaction, the sodium ion that dissociates out becomes sodium chloride.
To a certain amount of black liquor, lime, gypsum or calcium chloride are pressed the chemical reaction metering, and consumption should be suitable, perhaps excessive a little with the NaOH that this black liquor amount of generation is consumed.Lime is cheap, handles black liquor with it, outside the decapacitation chemical reaction, also has suction-operated, can be more excessive, in addition excessive 100～200%, still not very abuse lime.
During pulping by cooking, the amount of simple NaOH that dissolved lignin consumes only accounts for the sub-fraction of whole consumption amount of sodium hydroxide, and most of NaOH is consumed in the dissolving polysaccharide.Calcium chloride easily with black liquor in lignin reaction, so simple for precipitating lignin, the amount of the NaOH that dissolved lignin is consumed when the consumption of calcium chloride and boiling is suitable, and is perhaps excessive a little.During practical operation, the consumption of calcium chloride be, and the amount of NaOH that dissolved lignin consumes quite and with whole consumption amount of sodium hydroxide quite between.
Black liquor and lime reaction need heating; Below 80 ℃, reaction speed is too slow, does not have practical significance; More than 80 ℃, temperature is high more, and reaction speed is fast more; Temperature commonly used is a boiling temperature.Black liquor and gypsum or calcium chloride just can react at normal temperatures smoothly; Reasonably reaction temperature is the temperature of black liquor itself.
Black liquor is a liquid phase, and lime, gypsum and calcium chloride all are solid phases, for reacting smoothly, should fully stir.
Before the reaction, with the prior blowing air oxidation of black liquor, perhaps limit border ring blowing air oxidation helps to precipitate the organic matter of being with aldehyde radical.When the oxidation-reduction quality carrier of oxygen is arranged in the system, as quinones, blowing air effective.
To straw pulp black liquor, extraction rate of black liquor height again, the amount of extracting black liquor again is few, is very difficult.By method of the present invention, the black liquid extraction amount can be loosened to 12～16 tons of/ton slurries, even 12～18 tons of/ton slurries, can guarantee extraction rate of black liquor, alleviates the load of handling middle section water again.Before or after the additional alkali number of the clear liquid of separating, can increase evaporation-concentration step, make the amount of liquid balance of circulation.Evaporation and concentration does not herein have the problem of silicon fouling.
The amount of black liquor of pulp making is big, the ratio height of solid content, and the amount of solid precipitation is also very big.Implement when of the present invention, the work of Separation of Solid and Liquid is very arduous.For this reason, provide a kind of design of solid-liquid separation tank, for selecting for use.In order to accelerate solid precipitation sedimentation in solid-liquid separation tank, can in mixture, add flocculant commonly used and flocculation aid etc., as polyacrylamide and lime.
Can adopt the method and apparatus of any dry mud, the drying solid precipitation.The heat that can produce with incinerator, the drying solid precipitation.Certainly, make full use of solar energy, the energy is saved in air dry most.
In incinerator, the organic compound combustion in the solid precipitation is transformed into water and carbon dioxide.When solid precipitation contained sodium sulphate, the carbon that produces in the organic compound combustion process can reduce sulfate radical.The existence of an amount of calcium hydroxide makes reduzate be transformed into NaOH and calcium sulfide, and in high-temp combustion reaction subsequently, most of calcium sulfide is transformed into sulfur dioxide and calcium oxide.During the sulfate radical reduction, absorb big calorimetric, stablize, can not in solid precipitation, add too much sodium sulphate for guaranteeing to burn.Can only add an amount of sodium sulphate according to the requirement that replenishes alkali number.
Supplying the alkali source of alkali number, can be the alkali that oneself produces in the processing procedure; Also can be to replenish to add the sodium source alkali that in processing procedure, produces again.
Incineration ashes contains alkali, and the clear liquid dipping with separating dissolves alkali wherein, isolates then to contain the alkali clear liquid.With the clear liquid of separating or to contain the alkali clear liquid be solvent, comprise that the sodium source of trona and lime are raw material, successfully causticization goes out soda bath.Concentrate soda bath, dissolved impurity in the soda bath can be crystallized out.Prepare the cooking liquor that boiling is once more used with this soda bath and the clear liquid of separating.
The amount that contains the alkali clear liquid and its alkalinity according to slurry per ton produces add the lime of trona and respective amount, make causticizing reaction after, after the total alkali content in the clear liquid of separating by slurry per ton passes through following concentration at least, also enough boilings one ton of slurry that comes out.
The sodium chloride that black liquor and calcium chloride reaction produce is partly dissolved in the clear liquid, and part is dispersed in the solid precipitation.Product with part clear liquid dipping burning solid precipitation can be dissolved out sodium chloride wherein.In clear liquid, replenish and add proper amount of sodium chloride.To be dissolved in the sodium chloride electrolysis in the clear liquid again, and can directly produce NaOH, obtain containing the clear liquid of NaOH.Such clear liquid can directly use as cooking liquor; Also but evaporation and concentration after crystallization goes out inorganic impurity, is re-used as strong caustic, and the preparation cooking liquor uses.
The invention provides a specific embodiments is lime and black liquor reaction.
Four 25 cubic metres of rotary spherical digesters are arranged, produce the pulp mill of 20 tons of thick slurries every day.Extraction rate of black liquor 85%, 15 cubic metres of/ton slurries of extracted amount extract 300 cubic metres of black liquor every day.Solid content 7.7% in the black liquor; Total sodium content is amounted to into NaOH and is counted 1.7%; Inorganic content is 2.5%; Content of organics is 5.2%.
Extract the insulation storage tank that black liquor places 100 cubic metres of volumes, temperature can not be lower than 50.Black liquor is pumped into heat exchanger, use Steam Heating, 95 ℃ of heat exchanger outlet temperatures enter the reactor of four parallel connections in proper order by 12.5 cubic metres flow per hour.To each reactor, admit 25 cubic metres of black liquor with 2 hours, add 750 kilogram of raw lime after, the meter reaction time.Black liquor and lime is at boiling temperature, fully stirs reaction down after 4～5 hours, and product after reactor rest half an hour, is admitted the next round black liquor to solid-liquid separation tank with slush pump pump in half an hour again.Four reactor sequential workings are handled 300 cubic metres of black liquor every day.Like this, the black liquor treatment technology of just batch reactor being incorporated into continuous operation.
250 cubic metres of solid-liquid separation tank volumes, solidliquid mixture is advanced by the top of center inside groove, and through behind the settlement action, liquid is gone out by water jacket top circumference weir, and in conical lower portion, aqueous solid is extruded by rotary screw.The liquid that the weir goes out send evaporimeter after filtering, is evaporated to about 50% of original volume, and wherein alkali content is greater than 3%, behind the additional alkali number of producing with concentration 30% or more, mercury electrode or ion exchange electrode method of liquid caustic soda, uses as cooking liquor.
Aqueous solid, is made building materials and is used behind the elimination organic pollution through drying and incinerating.
In the above-described embodiment, alkali and organic content in the fluid sample after the analysis and filter: alkali content is greater than 1.7%; Content of organics is about 2%.Investigate the volume of raw black liquid and obtain the volume of liquid at last, calculate alkali recovery and be higher than 60%, organic removal rate is greater than 60%, and the lignin clearance is greater than 90%.
The invention provides another specific embodiments is black liquor and gypsum and calcium chloride reaction.
The ryegrass pulping factory that four 25 cubic metres of rotary spherical digesters are arranged produces 20 tons of thick slurries every day.Extraction rate of black liquor 85%, 14 cubic metres of/ton slurries of extracted amount produce 280 cubic metres of black liquor every day.The amount of solid content is 8.2% in the black liquor; Content of organics 5.5%; Inorganic content 2.7%; Amount to into total sodium content 1.82% of NaOH.
Swept volume 12 and 16 cubic metres, each two of the cylindrical stirred reactors of conical bottom, alternately continuous operation separately.In the black liquor that extracts, directly pump into the reactor of 12 cubic metres of volumes in the ratio of 6 tons of/ton slurries, behind enough 12 cubic metres of the black liquor, add 480 kilograms of gypsums, fully stir the decanter type solid-liquid separation tank that after 2～3 hours solidliquid mixture is pumped into 200 cubic metres of volumes from the conical bottom outlet.In the black liquor that extracts, directly pump into the reactor of 16 cubic metres of volumes in the ratio of 8 tons of/ton slurries, black liquor enough 16 cubic metres add after, add 400 kilograms in two hydration calcium chloride, fully stirred 2～3 hours, also mixture is pumped into the decanter type solid-liquid separation tank of 400 cubic metres of another volumes from the conical bottom outlet.Handle 280 cubic metres of black liquor every day with four reactors.
Solid-liquid separation tank also is the conical bottom cylindrical structural, and the bus of conical bottom and vertical direction angle are 50 degree.Mixture is advanced by the top of center inside groove, and through abundant sedimentation, more clear liquid goes out from water jacket top circumference weir.The liquid that the weir goes out filters with filter, obtains two kinds of clear liquids, goes into the clear liquid storage tank of oneself separately.Filter cake is incorporated solid precipitation into.
Aqueous solid precipitation in two solid-liquid separation tanks is extruded by the rotary screw of conical bottom setting respectively, combines.In the aqueous solid precipitation,, add 250 kilo sulfuric acid sodium by slurry per ton.Through super-dry, send into incinerator more again.Drying is utilized the heat of incinerator; In the season that temperature is higher, can utilize the solar energy air dry.Incinerator is with reference to the old-fashioned alkali recovery furnace of being made up of converter, combustion chamber and smelting furnace, and the boiler design of making fuel with the low heat value coal dust.The function of incinerator is to burn organic matter, reclaims heat energy, produces steam; In the burning, carbon reduces sodium sulphate, produces alkali.
Incineration ashes contains alkali.With the clear liquid that black liquor and gypsum reaction filter out, in the dipping dissolving tank, the alkali in the dissolving incineration ashes after fully stirring, filters out clear liquid.Sampling, titration alkali content wherein, the foundation of alkali number as a supplement.
Every day 280 cubic metres of black liquor, about 13 tons of deserved incineration ashes are with having dissolved from the clear liquid that the reaction of black liquor and gypsum obtains every day.
To contain the alkali clear liquid again and place causticization reactor, it is intact to contain alkali clear liquid causticization every day.Every day, causticization was used the amount of trona and lime, make the alkali number that causticization produces and contain alkali number in the alkali clear liquid to add and be in the same place, and through after the subsequent treatment, enough boiling uses every day.After the mixture Separation of Solid and Liquid after the causticization, with aqueous slkali evaporation and concentration to 350～400 grams per liter NaOH.The purpose that concentrates is for the sodium chloride in the solution, a spot of sodium sulphate and sodium carbonate are separated.Then, again the aqueous slkali that concentrates is added to black liquor and react in the clear liquid that filters out, be made into the cooking liquor that contains alkali 50 grams per liters, send the rotary spherical digester boiling with calcium chloride.Contain the sodium chloride that is lower than 12 grams per liters in the cooking liquor that is made into first, repeatedly circulation, the content of sodium chloride can increase, but never to 20 grams per liters.Experiment showed, that cooking liquor contains 12～24 grams per liter sodium chloride, the slurry quality that boiling goes out is unaffected.
After another embodiment provided by the invention is black liquor and calcium chloride reaction, be transformed into the concrete process program of cooking liquor.
Produce the paper mill of ten thousand tons of straw pulps per year, six 25 cubic metres rotary spherical digester is arranged, 30 tons in the thick slurry of daily output.Extraction rate of black liquor 85%, 14 cubic metres of/ton slurries of extracted amount extract 420 cubic metres of black liquor every day.The amount of solid content is 8.2% in the black liquor; Content of organics 5.5%; Inorganic content 2.7%; Total sodium content 1.82% in NaOH.
The black liquor of jetting storehouse and magma are sent pulp grinder to laundry and are extracted black liquor.Black liquor directly pumps into reactor from wash engine.30 cubic metres of reactor volumes, conical bottom, belt stirrer.Two continuous alternations of reactor.Per 30 cubic metres of black liquor add 750 kilograms in two hydration calcium chloride, fully stir 1～2 hour after, mixture is pumped into the decanter type solid-liquid separation tank from conical bottom outlet.
Solid-liquid separation tank also is the conical bottom cylindrical structural, and 10 meters of cylindrical part diameters, high 12 meters, the bus of conical bottom and vertical direction angle are 50 degree, about 1000 cubic metres of total measurement (volume).Mixture is advanced by the top of center inside groove, and through sedimentation in about 50 hours, more clear liquid went out from water jacket top circumference weir.
The liquid inflow filter that the weir goes out becomes clear liquid after filtration, goes into the clear liquid storage tank.
Aqueous solid is extruded by the rotary screw of conical bottom setting, sends to drying.
Use two kinds of drying modes simultaneously.A kind of is the drying room drying, utilizes between the tail gas stream super-dry of incinerator dry aqueous solid.Another kind is to utilize solar energy, air dry.Be dried to moisture content 10～15%, send incinerator to burn.Incinerator is burnt organic matter, produces steam.Product after the burning, promptly slag contains sodium chloride, calcium oxide and other inorganic impurity.
At the dipping dissolving tank,, dissolve sodium chloride wherein, again with the mixture Separation of Solid and Liquid with part clear liquid dipping slag.After the clear liquid of separating replenishes proper amount of sodium chloride, send electrolytic tank electrolysis.Through electrolysis, the sodium chloride in the clear liquid is transformed into NaOH, obtains chlorine simultaneously, and chlorine send bleaching process, and unnecessary chlorine is sold.The clear liquid that contains NaOH send evaporimeter, and the content that is evaporated to NaOH is about 400 grams per liters, and crystallization goes out the sodium chloride of not electrolysis.Strong caustic and clear liquid are mixed with cooking liquor, send the rotary spherical digester boiling again.
In above-mentioned three kinds of embodiments provided by the invention, do not use the too high vacuum pulp washing machine of cost, quintuple effect evaporator and alkali to reclaim and spray stove, reduce investment outlay significantly, eliminated black liquor pollution equally, reclaimed alkali.
The present invention also provides, and separates the solid-liquid separation tank of black liquor and lime, gypsum or the calcium chloride reaction mixture that produces, and its structural representation as shown in drawings.
Among the figure, the wall on sequence number 1 expression separating tank drum shape top; The wall of 2 expression conical bottom; 3 expressions are assembled in the screw rod that the conical bottom bottom can be extruded solid precipitation; The motor of 4 expression drive screws; 5 expression solid precipitation outlets; Precipitation in the 6 expression grooves; 7 expressions contain amount of solid liquid and weir seldom; The outlet of 8 express liquids; 9 expression solidliquid mixture inlets; The inner tube wall of 10 expression separating tanks.
The mixture that contains a large amount of solids descends by gravity from 9 inner cores that enter separating tank that enter the mouth.Outside the separating tank inner core, liquid rises, and solid precipitation descends.The solid precipitation that descends focuses on conical bottom, and the mixture of the total liquid level of separating tank causes big static pressure for the conical bottom lowest part, makes the solid precipitation moisture content less.With motor 4 drive screws 3 solid precipitation is extruded into outlet 5, leaves separating tank.The liquid that rises 7 flows to outlet 8 from the weir, leaves separating tank.
Above-mentioned solid-liquid separation tank is fit to separation and contains a large amount of solid precipitations and large numbers of solidliquid mixture.
Embodiment 1
Lime and the reaction of Xingtai black liquor.The black liquor sample, color is dark brown, and is opaque, and interior deposit-free, pH value are 9.Because of it is rarer, concentrate 2 times after, test with it again.
(1) basis analysis
1. pipette is got 10 milliliters of black liquor, records total sodium with the sulfated ash method: 0.09551 gram, count 16.60 grams per liters with NaOH.
2. pipette is got 10 milliliters of black liquor, after sulfuric acid and nitric acid acidifying, filters with ashless filter paper, after the calcination, records SiO
20.06301 gram is amounted to into 6.301 grams per liters.
3. pipette is got 10 milliliters of black liquor, places in the crucible of weighing with analytical balance, through 105 ℃ oven for drying, after the constant weight, records and contains solid content 0.7913 gram, amounts to into 79.13 grams per liters.
4. pipette is got 10 milliliters of black liquor, place weigh in the balance heavily, in the stainless steel crucible of an amount of quartz sand of interior dress, evaporation, calcination records total inorganic matter 0.3654 gram to constant weight again, amounts to into 36.54 grams per liters.
5. calculating 10 milliliters of content of organics in the black liquor is:
(79.13-36.54=42.59 grams per liter).Organic amount is on the low side in the black liquor, and the amount of inorganic matter is higher, may be the too much result of wheat straw dust.
(2) lime and black liquor reaction
In four-necked bottle, 3 liters of black liquor add 75 gram quick limes and a small amount of anthraquinone, feed compressed air, add thermal agitation, keep the temperature near boiling.When lime and black liquor reaction, want transpiring moisture inevitably.In order to compare with raw black liquid more exactly, experiment has been adopted to wait and has been held approximation method.Before evaporating off water divides, measure the cumulative volume of reactor internal reaction thing; When reaction, drip distilled water to reactor, keep cumulative volume constant.After reaction is carried out finishing in 2 hours.
(3) Separation of Solid and Liquid
Vacuum filtration is isolated liquid phase and precipitation.Liquid phase accounts for 75% of cumulative volume, and aqueous precipitate accounts for 25%.Liquid phase sample is the brownish red transparency liquid, and pH value is near 14; Solid precipitation is dark-brown.
(4) liquid phase sample
1. calcium ion in the detection liquid phase sample.After sample boils, add the capacity ammonium oxalate solution, do not observe white precipitate and produce.Conclusion is: liquid phase is calcium ions not substantially.
2. total alkali and NaOH in the mensuration liquid phase sample.
(1) be hydrochloric acid solution titration 5 ml samples that 0.1090mol/ rises with having demarcated concentration, count directing terminal with PH, be titrated to pH value=7 o'clock, with 19.2 milliliters of hydrochloric acid solutions, neutralization bases 0.4207mol/ liter, the total alkali of amounting to into NaOH is 16.6 grams per liters.
(2) earlier 20 milliliters of liquid phase samples are handled with barium chloride solution, got solution after the processing of suitable 5 milliliters of former liquid phase sample sizes again, with same hydrochloric acid solution titration, when being titrated to pH value 7, with 17.27 milliliters of hydrochloric acid solutions, in and NaOH 0.3786mol/ liter, close 15.13 grams per liters.
3. get 10 milliliters of liquid phase samples with pipette, after evaporation and the constant weight, record its solid content 0.441 gram in the baking oven, can amount to into 44.1 grams per liters.
4. get 10 milliliters of liquid phase samples with pipette, behind the pre-burn, recording inorganic content is 0.2709 gram, can amount to into 27.09 grams per liters.
5. content of organics in the liquid phase sample: 44.10-27.09=17.01 (grams per liter).Liquid phase sample is removed organic amount: 42.59-17.01=25.58 (grams per liter).
Liquid phase organic removal rate: remove organic amount in organic amount/black liquor
=25.58/42.59×％=60.06％
6. lignin: the experiment direct visual comparison, check the amount of removal lignin.
The black liquor of two cuvette cartridge same amounts and liquid phase sample, the abundant acidifying of hydrochloric acid with same amount is precipitated out lignin fully.Observe: after the black liquor acidifying, a large amount of brown lignin precipitations are arranged; And after the liquid phase sample acidifying, yellow mercury oxide is arranged, and deposit at the bottom of the test tube after leaving standstill, become brownly, its amount is less, after the not enough black liquor acidifying, be settled out 10% of lignin.
(5) burn solid phase
The dark brown solid precipitation is the mixture of lignin calcium, poly-Calciofon, calcium silicates, excessive hydrogen calcium oxide and other inorganic impurity.After burning in Muffle furnace, to become mainly be white, also a small amount of greyish black solid is arranged, and its main component is CaO, NaOH, SiO
2With other impurity, as iron, aluminium etc.
(6) slurrying experiment
The about 5 centimeter length wheat straws of 500 grams are placed in the boiling vessel, have 100 grams to wrap in the cotton gauze pocket; Add again from 4 and go up the solution of stating after the liquid phase sample evaporation and concentration to 2.7 that suction filtration comes out liter, add 0.3 gram anthraquinone and 9.1 gram caustic soda again.After fastening, heated 1.2 hours, Pressure gauge indication 0.3Mp, 135 ℃ of thermometer indications, little steam bleeding 5 minutes after Pressure gauge is reduced to 0.5Mp, stops steam bleeding.Continue heating 2 hours, Pressure gauge indication 0.6Mp, 160 ℃ of thermometer indications were incubated after 40 minutes, stopped heating.After the cooling, open boiling vessel, pour out dark brown slurry.Behind the extruding black liquor, add 0.5 liter of hot water and soak into, squeeze the secondary black liquor again; Heat water infiltration again, squeeze black liquor, 3 liters of coextrusion black liquor again.Straw pulp is made the sample oven dry after washing with a large amount of clear water.Sample and commodity Straw Pulp indifference.Weigh after the straw pulp oven dry in the cotton yarn cloth bag, calculating unscreened yield is 48.5%.
(7) repeat
The black liquor of extruding with oneself again with lime reaction, through finishing reaction in 2 hours; Isolate the solid-liquid two-phase, the outward appearance of solid-liquid two-phase is with last time identical.The liquid product that takes a morsel behind hcl acidifying, has only a small amount of lignin.
(8) brief summary
Experiment confirm: the direct and black liquor reaction of lime.In the liquid product of reaction, removed 90% lignin.This liquid is supplied alkali number, use, can boiling go out high-quality paper pulp as pulping and digesting liquid.The black liquor that boiling produces can be once more and lime reaction.
Embodiment 2
Paper mill, Linqing, Shandong continuously cooking send evaporation black liquor and gypsum reaction
(1) basis of black liquor is not analyzed in experiment.This is because Linqing factory provides, extraction rate of black liquor 85%, and solid content accounts for 12% in the black liquor, and basis is identical with black liquor composition in the textbook.
(2) gypsum and black liquor reaction
Add the gypsum (calcium sulphate dihydrate) of 180 grams with the mortar pulverize in 3 liters of black liquor, fully stir and be heated to 60 ℃, stir after 2 hours, reaction finishes.
(3) Separation of Solid and Liquid
Through long-time suction filtration, isolate 1.5 liters of clear liquids, the clear liquid brownish red, after lime and black liquor reaction, the clear liquid look of separating is shallow.Equally, estimate wherein to remain the content of lignin to be lower than 5% of raw black liquid with the hcl acidifying method.
(4) solid precipitation
The aqueous solid of separating is brown, in other words dark-brown.After being dried, be placed on the sheet iron, place on the 2KV electric furnace and heat, can oneself burn.Place Muffle furnace to burn, temperature is controlled at 1000 degree C, and incineration ashes is for mainly being white, also the solid of a small amount of grey black being arranged.
(5) alkali in the recovery incineration ashes
Get 10 gram incineration ashes, place 100 ml distilled waters, after fully stirring, go out clear liquid with funnel and filter paper filtering, the clear liquid water white transparency.The main component of filter residue is calcium oxide, a spot of calcium sulfide and other inorganic impurity.Get 5 milliliters of clear liquids with pipette, place conical flask, rise the salt acidometric titration with 0.109mol/, when being titrated to PH=9, consume 26 milliliters of hydrochloric acid, the clear liquid alkalinity is 22.6 grams per liters.
Illustrate: in the present embodiment, handle 3 liters of black liquor, can access the solid precipitation that how much restrains over dry, can burn out how much restrain incineration ashes, fail to provide data accurately and reliably.This be because, in the suction filtration process, change filter paper several times and cause filter cake loss too many, the result can't be quantitative.
Can estimate the amount of solid precipitation according to the amount of solid content in the black liquor and interpolation gypsum roughly; Estimate the amount of incineration ashes roughly according to the amount of inorganic content in the black liquor and interpolation gypsum.The amount of estimation incineration ashes should that is to say about 150 grams, can reclaim 33 gram alkali from incineration ashes, surpasses 40% of black liquor total alkali.
(6) use the brownish red clear liquid as cooking liquor
Handle 3 liters of black liquor with gypsum once more.Collect 3100 milliliters of clear liquids for twice altogether, incineration ashes 230 grams.With the alkali in 1500 milliliters of clear liquid dissolvings, the 230 gram incineration ashes, after the filtration, with remaining 1600 milliliters of clear liquids washing filter residue.Filtrate and cleaning solution are merged, amount to 2600 milliliters.To wherein adding 100 ml waters, gather into 2700 milliliters again.
Rise 5 milliliters of samples of salt acidometric titration with 0.109mol/, 21 milliliters of consumption acid, the sample alkalinity is 19.2 grams per liters.Claim 16 gram caustic soda, add in above-mentioned 2700 solution, be made into the cooking liquor of 25 grams per liter caustic soda.
In 5 milliliters of above-mentioned cooking liquor samples, add 45 ml distilled waters, drip the barium chloride solution that 0.1mol/ rises then, till no longer producing white precipitate.After the ashless filter paper filtration, the abundant washing precipitation of distilled water.Filter paper and precipitation are placed calcination in the crucible of having weighed, behind the weight, claim to such an extent that barium sulfate weighs 0.344 gram.The content of sodium sulphate is 42.2 grams per liters in the cooking liquor.
(7) pulping by cooking
Except that using above-mentioned cooking liquor, the boiling step as hereinbefore.Oven dry back Straw Pulp sample is compared with the commodity Straw Pulp, has than big difference, and color jaundice blackout, and many slurries of giving birth to are arranged.
(8) brief summary
Experimental results show that: gypsum can be removed most of lignin and organic principle in the black liquor under the normal temperature.Contains sodium sulfate has harmful effect to the boiling delignification more for a long time in the cooking liquor.
Embodiment 3
Handle the Linqing black liquor with calcium chloride
Add 100 grams, two hydration calcium chloride in (one) 3 liter of black liquor, fully stir 1 hour after, pour in the filter cloth pocket natural filtration into.Leach 1500 milliliters of clear liquids, it is faint yellow that clear liquid is.Check there is not the lignin that obviously exists in the clear liquid with the hcl acidifying method.
(2) with behind the filtration cakes torrefaction, place on the electric furnace and heat, filter cake can burn.Incineration ashes mainly is lime, sodium chloride, calcium silicates and other impurity on a small quantity.
(3) simulation trona causticization is that 10 to 1 mixture adds in 1500 milliliters of clear liquids with the weight ratios of 250 gram sodium carbonate and sodium sulphate, adds 150 again and restrains quick limes.Fully stir, be heated to and boil, keep boiling after 1 hour, Separation of Solid and Liquid.Isolate 1200 milliliters of clear liquids, 5 milliliters of clear liquids of titration wherein contain alkali 120 grams per liters.
(4) in 560 milliliters of described clear liquids, add the clear liquid that leaches in the step (), to cumulative volume be 2700 milliliters, as cooking liquor, carry out slurrying experiment by above-mentioned.The Straw Pulp sample of making and other sample compare, and color is slightly white.
(5) conclusion
Experimental results show that: handle black liquor with calcium chloride, with the clear liquid pulping by cooking that leaches, can obtain the high-quality Straw Pulp again.
Embodiment 4
Electrolysis is reacted the sodium chloride-containing clear liquid that filters out from calcium chloride and black liquor
(1) press step among the embodiment three, the clear liquid of preparation sodium chloride-containing, the content of sodium chloride is 40 grams per liters in the clear liquid.
(2) 2 liters of clear liquids are placed the cathodic region of electrolytic cell, make negative electrode with stainless (steel) wire.
(3) isolating with biscuit ware between cathodic region and anode are got, be full of saturated aqueous common salt in the anode region, is anode with the titanium electrode, and about 1.5 square decimeters of annode area adds 6.8 volts of voltages between anode and the negative electrode, and the ammeter indication has 6 Ampere currents.
(4) electrolysis was taken out the salt acidometric titration that 5 milliliters of cathodic region solution rise with 0.1055mol/ after 6 hours, and the solution alkalinity is 25.5 grams per liters; The anode region has chlorine to overflow during electrolysis.
(5) solution that contains alkali 25.5 grams per liters that electricity consumption separates out carries out the pulping by cooking experiment as cooking liquor, and the Straw Pulp sample of making is compared with other sample, does not have significant difference.
The foregoing description just further specifies design of the present invention.Can not be interpreted as that the present invention is only limited to the scope of the foregoing description.
Claims (8)
1. black liquor of pulp making is processed into the cooking liquor that boiling is once more used, prevents the method for black liquor pollution, it is characterized in that comprising the steps:
(1) solid content and the calcium ion in lime, gypsum or the calcium chloride in the black liquor of pulp making are reacted, generate the water-insoluble solid precipitation;
(2) Separation of Solid and Liquid;
Burn the dry back of aqueous solid precipitation of (3) separating;
(4) after the clear liquid of separating is supplied alkali number, become the cooking liquor that boiling is once more used.
2. the described method of claim 1 is characterized in that, wherein the described alkali source of supplying alkali number of step (4) comprises:
(1) be solvent with the clear liquid separated, comprise that the sodium source of trona and lime are raw material, the caustic soda that causticization produces and
(2) be solvent with the clear liquid of separating, black liquor and calcium chloride reaction sodium chloride that produced and that replenish interpolation is raw material, the caustic soda that electrolysis produces.
3. the described method of claim 1 is characterized in that, wherein also comprises, before burning solid precipitation, adds the step of sodium sulphate.
4. the described method of claim 1 is characterized in that, wherein also comprise, and with the clear liquid separated dipping incineration ashes, the step that wherein alkali or sodium chloride are dissolved out.
5. the described method of claim 1 is characterized in that, black liquor and lime reaction, and concrete processing step comprises:
(1) extract black liquor by 12～18 tons of/ton slurries, the black liquor of extraction and lime fully stir at 80 ℃～boiling temperature, have under the condition of a small amount of quinones existence and bubbling air to react;
(2) Separation of Solid and Liquid is that the first using right profit requires 8 described solid-liquid separation tanks to separate, and with isolated liquid filtering, obtains clear liquid again;
(3) behind the heated drying of the aqueous solid of separating with the incinerator generation, burn with incinerator again;
(4) clear liquid of separating makes the amount of liquid balance that recycles earlier through evaporation and concentration, supplies alkali number again, becomes the cooking liquor that boiling is once more used.
6. the described method of claim 1 is characterized in that, black liquor reacts with gypsum and calcium chloride respectively, and concrete processing step comprises:
(1) extract black liquor by 12～18 tons of/ton slurries, the part of extraction black liquor and calcium chloride, remainder and gypsum react under the well-beaten condition in the temperature of black liquor itself;
(2) separate the solidliquid mixture that the reaction of black liquor and gypsum and calcium chloride produces respectively, obtain two kinds of clear liquids;
(3) before burning, the solid precipitation of separating is respectively combined, burn again;
(4) use the clear liquid dipping incineration ashes that obtains from the reaction of black liquor and gypsum, dissolving alkali wherein, Separation of Solid and Liquid goes out to contain the alkali clear liquid again;
(5) amount that contains the alkali clear liquid and its alkalinity that produces according to slurry per ton adds the lime of trona and respective amount, make causticizing reaction after, after separating total alkali content in the clear liquid and pass through following step process at least by slurry per ton, also enough boilings go out 1 ton of slurry;
(6) with the clear liquid evaporation and concentration of separating after the causticization, except that NaOH, other solute can crystallize out in solution, isolates strong caustic again;
(7) react the clear liquid preparation cooking liquor that obtains with the strong caustic of separating with from black liquor and calcium chloride.
7. the described method of claim 1 is characterized in that, black liquor and calcium chloride reaction, and after the Separation of Solid and Liquid, the clear liquid of electrolysis sodium chloride-containing again, concrete processing step comprises:
(1) presses 12～18 tons of/ton slurries and extract black liquor, extract black liquor and calcium chloride and under black liquor self-temperature and abundant stirring condition, react;
(2) Separation of Solid and Liquid goes out the clear liquid of aqueous solid and sodium chloride-containing;
(3) behind the heated drying of the aqueous solid of separating with the incinerator generation, burn with incinerator again;
(4) the part clear liquid dipping incineration ashes that obtains with step (2), dissolving sodium chloride wherein, Separation of Solid and Liquid goes out clear liquid again;
(5) replenish sodium chloride, clear liquid is placed the electrolytic cell electrolysis again, the sodium chloride that dissolves in the clear liquid is transformed into NaOH;
(6) after evaporation and concentration contains the clear liquid of NaOH, prepare cooking liquor with it.
8. the decanter type solid-liquid separation tank of being made up of cylindrical upper section 1 and conical bottom 2 is characterized in that, separating tank also comprises the screw rod that is assembled in the conical bottom bottom, and drive screw can be expressed to solid precipitation outlet 5, leaves separating tank.
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| CN 00129510 CN1285436A (en) | 2000-09-29 | 2000-09-29 | Method and equipment for treating black liquor into boil solution |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104032612A (en) * | 2014-06-17 | 2014-09-10 | 毛林涛 | Method for extracting lignin from alkaline straw pulp black liquor |
| CN104594089A (en) * | 2014-12-22 | 2015-05-06 | 金东纸业（江苏）股份有限公司 | Chemi-mechanical pulp preparing method and device |
| CN105044784A (en) * | 2015-08-14 | 2015-11-11 | 河海大学 | Dual-probe-rod submarine cable detection system and detection method thereof |
| CN110054334A (en) * | 2018-01-18 | 2019-07-26 | 金东纸业（江苏）股份有限公司 | A kind of pretreatment system of pulping waste liquor |
-
2000
- 2000-09-29 CN CN 00129510 patent/CN1285436A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104032612A (en) * | 2014-06-17 | 2014-09-10 | 毛林涛 | Method for extracting lignin from alkaline straw pulp black liquor |
| CN104594089A (en) * | 2014-12-22 | 2015-05-06 | 金东纸业（江苏）股份有限公司 | Chemi-mechanical pulp preparing method and device |
| CN104594089B (en) * | 2014-12-22 | 2017-05-17 | 金东纸业（江苏）股份有限公司 | Chemi-mechanical pulp preparing method and device |
| CN105044784A (en) * | 2015-08-14 | 2015-11-11 | 河海大学 | Dual-probe-rod submarine cable detection system and detection method thereof |
| CN110054334A (en) * | 2018-01-18 | 2019-07-26 | 金东纸业（江苏）股份有限公司 | A kind of pretreatment system of pulping waste liquor |
| CN110054334B (en) * | 2018-01-18 | 2021-11-23 | 金东纸业（江苏）股份有限公司 | Pretreatment system of pulping waste liquid |
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