Summary of the invention:
The object of the present invention is to provide a kind of method for preparing bleach chemical pulp by cotton stalk.
The method of the invention is a soda pulping process.
The method of the invention is, with the processing of getting the raw materials ready of above-mentioned cotton stalk, impregnation process by once boiling or secondary boiling, is slightly starched, and through pulp washing, bleaching makes finished paper.
The described processing of getting the raw materials ready is that cotton stalk should be removed root before use, and carries out conquassation or break process.
Above-mentioned getting the raw materials ready handled after conquassation or break process, preferably further skin separated with bar, and skin and bar are carried out slurrying production respectively.
Because the difference of constituent structure, the alkali charge that uses cotton stalk bark is less than the alkali charge that uses the peeling cotton stalk separately, thereby separating treatment can be avoided because of the two difference on composition, and the one-tenth pulp yield that causes is low; Do not remove the peel cotton stalk when boiling, bigger than cotton stalk bark alkali charge, so, being regardless of defection and causing the serious or peeling cotton stalk steaming of cotton stalk bark degraded itself to separate deficiency, the one-tenth pulp yield that these all can cause is low.
Described impregnation process is that the cotton stalk after will get the raw materials ready handling floods with maceration extract, makes liquor ratio reach 1: (4-5.5), under normal pressure in insulation more than 85 degrees centigrade and mix more than 10 minutes, wherein in the condition insulation of 85-95 degree with mix 10-40 minute for well.
The content of alkali is the 25-35 grams per liter in the described maceration extract, and the weight ratio of over dry material quantity and the total liquid measure of maceration extract is 1: 2.5-3.6; The used black liquid consistency of impregnation process is 11-14 ° of Be ' (20 ℃ time), is preferably 12-14 ° of Be ' (20 ℃ time), and solid concentration 14-20% is preferably 16-20%.Said maceration extract is to contain the dense black liquor of certain alkali, is the mixed liquor of alkali and black liquor, and the Controllable Temperature of black liquor is between 80-95 ℃, and the alkali that adds in the black liquor can be caustic soda (NaOH), and addition is controlled at the 25-36 grams per liter, is preferably the 28-32 grams per liter.Black liquor can directly adopt the waste liquid that produces in the digestion process of preparation straw pulp, (liquor ratio reaches 1: 4-5.5) repetitive cycling is used the black liquor that produces in the preparation straw pulp under the condition of big liquor ratio like this, improve the extraction concentration of black liquor, reduce the discharge capacity of black liquor, thereby reach to concentrate and administer, alleviate the purpose of environmental pollution and water saving, also guaranteed simultaneously liquid phase cooking, the realization of circulation in the pot, displacement and heat washing.
The concentration of the used black liquor of this stage impregnation process is 11-14 ° of Be ' (20 ℃ time), is preferably 12-14 ° of Be ' (20 ℃ time), and solid concentration 14-20% is preferably 16-20%.Wherein, pH value is 11-14, preferred 11.8-13.3, and residual alkali number is the 8-12 grams per liter, is preferably the 8-10 grams per liter, COD is 150000-180000mg/l, is preferably 160000-180000mg/l.
Above-mentioned is 60-70% through holocellulose weight percentage in the cotton haulm raw material of dipping, and total lignin weight percentage is 12-20%, and the poly-pentose weight percentage is 20-25%, and yield is by 86-92%.
Said yield is by after the 100 gram fibrous raw material impregnation process, dries the ratio of weighing with 100 gram raw materials again.
The inventive method can use the once boiling method to realize.
The process of once boiling is: cotton haulm raw material is put into boiling vessel, caustic soda concentration 400g/L, join alkali concn 65-90g/L, preferred 78.8g/L, behind the preceding running of the once boiling 20min, in boiling vessel, feed water vapour, the 40min that once heats up, make pressure in the boiling vessel reach 0.3-0.4Mpa after, little pressure of exitting to boiling vessel is 0-0.02Mpa, feed steam once more, make the pressure in the rotary spherical digester reach 0.3-0.4Mpa, under the pressure condition of 0.3-0.4Mpa, carry out secondary temperature elevation, the secondary temperature elevation time is 40 minutes, temperature retention time 75-95min under the pressure of 0.3-0.4Mpa spurts 25min, discharge opeing then.
Behind the once boiling, the residual alkali 14.88-16.43g/L of black liquor that extracts, starch degree K value is 10.5-12.7, slurry is 23-26 ° of SR of beating degree when the horizontal belt wash engine, the weight in wet base 2.0-2.5g of this moment, level band hardness 14, residual alkali 0.08g/L when starching out the horizontal belt wash engine, beating degree 25-28 ° SR when decker, weight in wet base 1.9-2.0g, hardness 12.6-13.
The inventive method also can use the secondary boiling method to realize.
Adding alkali is operating as: caustic soda concentration 400g/L, join alkali concn 40-60g/L, and preferred 47.2-51.6g/L, it is 17% that one-level is boiled alkali charge, pressure black liquor amount 5-7m
3, secondary boils and adds alkali number 0.8-0.95m
3, secondary boils alkali charge 10%;
The boiling operating process is: cotton haulm raw material is packed in the boiling vessel, running 10min before one-level is boiled, add steam and carry out once boiling, behind the heating-up time 30min, once little venting 10min, add the steam 40min that heats up for the second time again, pressure black liquor 90min carries out secondary again and boils and add alkali, carries out intensification 40-60min behind the 20min three times, secondary boils temperature retention time 100-130min, spurts 15-20min.
The residual alkali 17.8-21.21g/L of boiling, hardness K value is 12.2-15, slurry is 22-25 ° of SR of beating degree when the horizontal belt wash engine, weight in wet base 2.1-2.7g, hardness 10.5-13.3, residual alkali 0.04-0.2g/L when starching out the horizontal belt wash engine, slurry beating degree 24-25 ° SR before floating, weight in wet base 2.0-2.7g, hardness 10.1-11.7.
The black digestion liquid index is:
The COD that extracts black liquor at the horizontal belt wash engine behind the once boiling is 144530mg/L, and the pH value is 13, Baume degrees (15 ℃ time) 11.604, and solid content is 14.57%, viscosity is 5.4cps/19.2 ℃, acid non-soluble substance 51700mg/L;
The COD of the one-level row black liquor of secondary boiling is 181390-187210mg/L, the pH value is 13.05-13.44, Baume degrees (15 ℃) 14.078-14.656, and solid content is 18.55-19.19%, viscosity is 7.7-8.5cps/ (18.3-19.0 ℃), acid non-soluble substance 66000-78700mg/L;
COD at horizontal belt wash engine extraction black liquor after the secondary boiling is 154230-157140mg/L, the pH value is 13.11-13.15, Baume degrees (15 ℃) 12.052-12.078, and solid content is 15.61-16.09%, viscosity is 4.7-5.5cps/18.0 ℃, acid non-soluble substance 64700-70000mg/L;
It is 853.6mg/L that one-level is boiled middle section water COD, and SS is 530mg/L;
It is 582-853.6mg/L that secondary boils middle section water COD, and SS is 450-460mg/L.
The bleaching of cotton stalk pulp: pipeline floats logical chlorine dose 60-80kg/ ton slurry, and pipeline floats logical alkali number 9-13kg/ ton slurry, and hardness was 4.1-5.0K before the H section was floated, the dense 4.5-5.0% of slurry before floating, and bleaching concentration is 30g/L, the bleaching liquor addition 0.06-0.1m of every side's slurry
3, bleaching time 130-210min, bleachability is 3.0-7.0%, floats pond whiteness 74.6-78.5%, floats the residual chlorine 0.17-0.31g/L in back, final whiteness is 78.9-82.0%.
The cotton stalk pulp intensity index:
The once boiling making beating: beating degree is 31-47 ° of SR, weight in wet base 1.6-2.6g, quantitatively 59.3-60.1g/m
2, bulk 1.871-2.248cm
3/ g, fracture length 3.768-4.986Km, folding strength 11-22 time, tearability 742-774mN.
Secondary boiled making beating: beating degree is 29-46 ° of SR, weight in wet base 1.6-2.7g, quantitatively 58.5-60.3g/m
2, bulk 1.800-2.193cm
3/ g, fracture length 3.529-5.320Km, folding strength 5-20 time, tearability 225-286mN.
Beneficial effect:
1, traditional view is thought, undesirable with the slurry quality that cotton stalk makes, pulp yield is low, and alkali charge is big, and the finished paper that makes is of low quality; The present invention has abandoned and has thought that cotton stalk can not make traditional prejudice of slurry, by raw material being carried out preliminary treatment, conditions of cooking, conditions of bleaching being improved, has obtained the desirable cotton stalk chemical pulp of performance indications.
2, use the cotton stalk chemical pulp of the inventive method preparation, bleachability is good, can reach the index of wheat straw bleached pulp, satisfies the preparation requirement of bleach chemical pulp fully.
3, the chemical pulp of the inventive method preparation, washing easily, the extraction rate of black liquor height, middle section water COD index is very low, has reduced the clear water consumption when extracting black liquor.
4, the cotton stalk chemical pulp of the inventive method preparation is used to join and copies finished paper, and every index does not have significant change, can be used for substituting the poplar slurry fully, has alleviated the shortage of timber resources, provides valuable method to effective utilization of cotton stalk resource.
The specific embodiment:
Embodiment 1
Cotton stalk pulp boiling cost analysis:
7 balls are produced in test altogether, 11.0644 tons of output, 29.32 tons of consumption over dry cotton stalk amounts, yield rate 37.74%.
Experimental example 1
Cotton stalk once boiling record data table:
Cotton stalk secondary boiling record data table:
The cotton stalk bark fibre average length is 2.0mm, average diameter 20um; The average length of wooden core fibre is 0.74mm, and average diameter is 16um; It is more that the cotton stalk bast contains pectic substance, can find out during the course, and the pectic substance degradation product is present in the slurry in a large number, need not add starch indicator when detecting hardness; Therefore, cotton stalk preferably stores more than half a year before using, and in order to spontaneous fermentation, saves boiling alkali.
Alkali lye is difficult for infiltration during the direct boiling of cotton stalk, and raw material preferably carries out conquassation or break process, helps improving the penetrating power of alkali lye, makes boiling more even, also will significantly reduce thick slag or fibre bundle.Test with cotton stalk fully conquassation smash, so the alkali lye dipping effect is good, laboratory test is with the raw material weak effect of getting the raw materials ready, the alkali charge of formulating is also high, and therefore, the pilot plant test alkali charge is higher, the residual alkali height of black liquor, part material may steam, and the slurry beating degree is also higher; Can find out that by current test cotton stalk is got the raw materials ready pulp quality is had very big influence; The difficult steaming of cotton stalk root separated, and improving alkali charge can not pulping, removes at the big sieve place of jumping substantially, and cotton stalk bark etc. easily steam to be separated component and then degrade seriously, is lowered into pulp yield, and this can hang down from the pulping weight in wet base and embody; Therefore, for guaranteeing stock quality and yield, can suitably reduce alkali charge.
Experimental example 2
The bleaching data:
No. 1 pond is the once boiling slurry, and all the other are secondary boiled slurry, stablizes for guaranteeing pulp brightness, form and aspect, and several ponds, back bleaching liquor consumption increases to some extent; Under laboratory condition, floating disposed slurry has a large amount of dust, and therefore, bleaching is the emphasis of this test, also has a mind to reduce hardness when boiling, and from the result, cotton stalk pulp is than easily floating of estimating, after logical chlorine was handled, final whiteness can reach more than 78%.
Experimental example 3
Cotton rod boiling black liquor index detects table:
Black liquor:
Middle section water:
Indexs such as cotton stalk black liquor of pulp making COD, Baume degrees, solid content are all than giantreed, wheat straw index height, and middle section water COD, SS are very low, illustrate that the cotton stalk pulp black liquid extraction is effective, help black liquid extraction and reduce the clear water consumption.
Experimental example 4
The intensity index data:
The making beating of once boiling laboratory:
The making beating of secondary boiling laboratory:
The fibre analysis tables of data:
1, frequency of fibers distributes (%), cotton stalk once boiling slurry laboratory defibrination
Length of interval |
(31,2.6) |
(35,2.2) |
(40,2.2) |
(47,1.6) |
0.07~0.42 |
66.30 |
65.78 |
68.68 |
68.99 |
0.42~0.82 |
27.85 |
27.75 |
25.35 |
24.28 |
0.82~1.22 |
4.85 |
4.90 |
4.53 |
4.85 |
1.22~1.62 |
0.75 |
1.03 |
0.93 |
0.83 |
1.62~2.02 |
0.30 |
0.33 |
0.20 |
0.30 |
2.02 more than |
0.23 |
0.23 |
0.33 |
0.20 |
2, fibre morphology analysis
3, the secondary boiled slurry of frequency of fibers distribution (%) 3# workshop cotton stalk laboratory defibrination
Length of interval |
(29.0,2.7) |
(34.5,2.6) |
(43.0,1.7) |
(46.5,1.6) |
0.07~0.42 |
64.33 |
64.35 |
65.25 |
65.45 |
0.42~0.82 |
29.23 |
29.65 |
28.70 |
29.05 |
0.82~1.22 |
5.03 |
4.90 |
4.82 |
4.43 |
1.22~1.62 |
0.90 |
0.43 |
0.75 |
0.68 |
1.62~2.02 |
0.30 |
0.15 |
0.40 |
0.18 |
2.02 more than |
0.23 |
0.23 |
0.08 |
0.23 |
4, fibre morphology analysis
Analyze from the fibre analysis data: the cotton stem pulp of once boiling is after beating degree reaches 40 ° of SR, 0.42mm following fiber content obviously increases, 0.42-0.82mm between fiber content obviously reduce, after this pull an oar the cutting action of fiber is strengthened, the intensity index of slurry descends, in the making beating curve same result is arranged also, slurry intensity index when 40 ° of SR left and right sides of beating degree is best.In low beating degree scope, the fibre length fall of slurry is less, can find out also that from the making beating curve weight in wet base of slurry changes not obvious, this illustrates that also the cotton stalk slurry easily pulls an oar, the suction swollen performance of fiber is good, the easy wire-dividing broom purification of fiber, and the intensity index of slurry is better.
This is tested secondary boiled slurry and compares with the once boiling slurry, and tearability changes greatly, and is different with the result that pulled an oar for several times in the past, and these group data await further checking.
Comparative example 1-3 is that cotton stalk pulp is joined and copied art paper experiment, in process of the test, has carried out joining of 20%, 30%, 40% 3 proportioning of cotton stalk pulp copying test, stablize the consumption of needle slurry 31%, straw pulp 29% simultaneously, cotton stalk pulp and poplar is starched compare; Starch, CaCO in the slurry
3And other various auxiliary dosages remain unchanged.
Comparative example 1
Production technology is according to 128g/m
2Art paper carries out, and wet end furnish is:
Project |
Unit |
1 |
2 |
3 |
4 |
Needle slurry consumption |
% |
31 |
31 |
31 |
31 |
Poplar slurry consumption |
% |
40 |
20 |
10 |
0 |
The cotton stalk pulp consumption |
% |
0 |
20 |
30 |
40 |
The straw pulp consumption |
% |
29 |
29 |
29 |
29 |
Starch consumption in the slurry |
Kg/ ton slurry |
18.8 |
18.8 |
18.8 |
18.8 |
The retention agent consumption |
ppm |
500 |
500 |
500 |
500 |
Auxiliary dosage |
Kg/ ton slurry |
140 |
140 |
140 |
140 |
Beating process requires:
Testing result:
Can know according to above result, because the cotton stalk pulp fiber is soft, making beating easily.
Learn that from the making beating curve cotton stalk pulp easily divides silk, brooming, bond strength is good between the fiber, beating degree about 40 ° of SR in, cotton stalk pulp has best intensity index; So when the control refining pulp quality, will select the making beating of moderate strength, guarantee that fiber well divides silk, brooming, and too do not cut off; Microscopic examination after the production process making beating, the cotton stalk pulp fiber produces a desired effect.
Comparative example 2
Paper machine technological parameter:
Index |
Unit |
No cotton stalk pulp |
20% cotton stalk pulp |
30% cotton stalk pulp |
40% cotton stalk pulp |
The speed of a motor vehicle |
m/min |
186 |
186 |
189.9 |
190.9 |
Couch roll vacuum |
MPa |
0.08 |
0.08 |
0.075 |
0.076 |
Suction moves roller vacuum |
MPa |
0.06 |
0.06 |
0.06 |
0.06 |
One pressure pressure |
MPa |
0.45/0.46 |
0.45/0.46 |
0.46/0.45 |
0.46/0.45 |
Two pressure pressures |
MPa |
0.45/0.45 |
0.45/0.45 |
0.45/0.45 |
0.45/0.45 |
Positive pressure pressure |
MPa |
0.48/0.48 |
0.48/0.48 |
0.48/0.44 |
0.48/0.45 |
Optical pressure pressure |
MPa |
0.05/0 |
0.05/0 |
0.04/0 |
0.05/0 |
Coating vapour pressure the last period |
MPa |
0.281 |
0.333 |
0.313 |
0.336 |
Be coated with the first two section vapour pressure |
MPa |
0.074 |
0.124 |
0.101 |
0.112 |
Be coated with back one section vapour pressure |
MPa |
0.302 |
0.312 |
0.301 |
0.336 |
Become the paper achievement data:
By last table data as seen, after slurry partly replaces the poplar slurry, become the paper folding strength to improve, all the other indexs change little, and page tries seal on four look Heidelberg printing machines respond well, do not have bad effect and produce, and printed patterns is clear.
Comparative example 3
Cotton stalk is joined and is copied electro-photographic paper, and production technology is according to 60 gram/m
2Electro-photographic paper carries out.
Batching:
Cationic starch (KG/T slurry): 8
AKD (KG/T slurry): 10-12
Calcium carbonate (KG/T slurry): 150
During experiment, the cotton stalk pulp with 66% replaces the poplar slurry fully, and straw pulp is from slurrying three workshops, and other production technologies remain unchanged, and paper machine speed is controlled at 138-140m/min, the one-tenth paper index before and after the contrast experiment.Become paper to refer to
Mark as following table:
After cotton stalk pulp was used for electro-photographic paper and replaces poplar slurry fully, it was little to become the paper index to change.