CN1103450A

CN1103450A - Straw pulp black liquor silicon removing method

Info

Publication number: CN1103450A
Application number: CN 93114946
Authority: CN
Inventors: 汪萍; 张珂; 邹培昌; 冯旭东
Original assignee: BEIJING LIGHT INDUSTRY COLLEGE
Current assignee: BEIJING LIGHT INDUSTRY COLLEGE
Priority date: 1993-12-01
Filing date: 1993-12-01
Publication date: 1995-06-07
Anticipated expiration: 2013-12-01
Also published as: CN1042964C

Abstract

The process for removing silicon from black liquor of straw pulp features that silicon remover is added in alkali lye tank before digestion or directly in digestion pot with amount of 10-50 kg per ton of black liquor. The slicon remover is a mixture of alumina or aluminium hydroxide containing by-product in aluminium refinery, leftover containing alkaline matter in alkali industry and lime stone.

Description

Straw pulp black liquor silicon removing method

The present invention is a kind of simple and easy new method of silica removal in the non-wood fibrous raw material alkaline pulp black liquor, particularly is suitable for having the occasion of waste liquid chemical recovery.Here said soda pulping process is refered in particular to the slurrying of the inferior sodium method of soda processes, sulfate process and alkali formula.

Adopt non-wood-fiber, making pulping raw material as straw, wheat straw, reed, reed reed, bagasse, bamboo etc. is very general in the third world, probably accounts for 60% of total slurry amount in China, wherein again based on wheat straw.Non-wood fibrous raw material has been drawn a certain amount of SiO from soil in growth course ₂, in alkaline boiling, most of silicon dissolves in black liquor, and black liquor silicone content and viscosity are raise.High silicon content, full-bodied black liquor enter the chemical recovery system, and easily fouling on evaporator surface reduces heat transfer efficiency greatly; Force the alkali stove to improve temperature during burning again, not only increase heat loss but also increase carry-over loss, and, owing to contain too much calcium silicates in the white clay, make white clay lose recovery value.

As far back as 1932, in Britain's application specification (GB381697), the researcher has just proposed can be before boiling or in the boiling, add one or more metal oxides or hydroxide in cooking liquor, be adsorbed on reduction black liquor silicon content on the slurry so that silicon forms insoluble matter, these metals can be aluminium, calcium, zinc, magnesium etc.The researcher also advises, can replace aluminium oxide to use by bauxite, do not use but will not hinder in the color and luster problem that bauxite brought under the purposes prerequisite of fiber.

US4331507 is an invention that relates to several black liquor silicon removing methods.They point out, bauxite is uniquely to be suitable for and to provide the source of aluminium oxide economically, although contain the coloring matter di-iron trioxide in the bauxite, the slurry look will be become to be increased.

This invention comprises three parts altogether, 1. after former alkali reclaims causticization, increases a reactor and a separator.White liquid and bauxite are reacted in reactor, after impurity (as di-iron trioxide) is removed in separation, remove digester then.2. to flow process improvement 1., the reactor in 1. and separator are moved to after the wash engine, before the evaporimeter.That is to say bauxite is added in rare black liquor of extraction, separate white residue and black liquor then.Because bauxite do not contact with black liquor, think that the color and luster to slurry does not have influence.3. to flow process improvement 1., reactor and separator are moved on to after one section evaporation, promptly bauxite is added in half concentrated black liquid after 1 section evaporation.It is difficult that 3. 2. flow process exist white residue to separate, the bulky problem of white residue, and also process is simple inadequately, and equipment investment, operating cost all are problems.1. flow process also exists liquid-slag to separate, but is not white residue but insoluble matter in white clay and the bauxite.This patent does not show any mask data about bauxite insoluble matter and di-iron trioxide and white liquid, and therefore, the removal effect of relevant iron oxide also is a unknown number.In addition, dissolution velocity is unhappy at normal temperatures and pressures owing to bauxite, have the enough reaction time will increase reactor volume, otherwise bauxite can not total number be used, and makes separation slag volume lose alkali number greatly.

Find also in the experiment that the silicon that contains in the bauxite also can be dissolved in the alkali lye along with the prolongation of the time of staying in reactor, so the high bauxite of silicone content causes the silica removal effect significantly to reduce.

The object of the present invention is to provide the extremely simple and boiling of a kind of silica removal process to carry out synchronously, need not to add the efficient silica removal new method of any new equipment.

The method that the present invention proposes adopts a kind of cheap desiliconizing agent, and it is made up of pair product A, chlorine industry leftover bits and pieces H, the lime stone M of aluminum smelting industry, and mixing ratio (weight ratio, down together) is A: H: M=100: 0-10: 0-5.Aluminum smelting industry has multiple by product, wherein contains the present invention that may be used to of aluminium oxide or aluminium hydroxide.The leftover bits and pieces that is used for chlorine industry of the present invention should contain alkaline matter.Composition Main Ingredients and Appearance of the present invention is the oxide of aluminium, sodium, potassium, calcium, magnesium etc., contains iron oxide hardly.This mixture is soluble in hot alkaline solution after pulverizing, so the desiliconizing agent that proposes of the present invention can be added in joining the alkali groove or directly be added in the digester before the boiling.As be added in and join in the alkali groove, needing to stir and heating, heating-up temperature is more than 80 ℃, to promote dissolving.Non-wood-fiber per ton need add desiliconizing agent 10-50 kilogram approximately.The alkali for preparing is added to boiling in the rotary spherical digester simultaneously together with desiliconizing agent.Pulping process can adopt the inferior sodium method of sulfate process, soda processes or alkali formula.Because this desiliconizing agent fine solubility, it is few to cause colored foreign, and need not the impurity separation means, and by boiling, the insoluble matter that aluminium and silicon generate just is adsorbed on the slurry.In washing process, slurry and black liquid separation make silicon leave black liquor naturally, and reach the purpose that reduces silicone content in the black liquor.

On the small-sized electric steamer of the 15l of laboratory, adopt not silica removal sulfate pulping (as example 1) of wheat straw standard, 5 averages of the black liquor silicon content that obtains are 3.54g/l, and are as shown in table 1.Adopt identical pulping process, (desiliconizing agent mixing ratio A: in the time of H: M=100: 10: 5), silica removal efficient reaches 55-97%, can reach best silica removal effect when wheat straw per ton adds 25kg mixing desiliconizing agent, sees Table 2 to add the different desiliconizing agents of measuring.

Table 1 does not add silicon content in the desiliconizing agent ryegrass pulping black liquor

12345 is average

PH 11.08 11.52 11.22 11.29 11.12 11.25

Be'(20℃) 8.7 8.6 9.5 8.6 10.32 9.14

Silicon content (g/l) 3.92 3.73 3.92 3.07 3.08 3.54

Table 2 adds silicon content in the different amount desiliconizing agent ryegrass pulping black liquor

1 2 3 4 5 6

PH 11.58 11.86 12.04 11.03 12.44 10.98

Be'(20℃) 8.9 10.0 9.0 8.4 7.7 8.2

Desiliconizing agent consumption (‰) 10 15 17.5 25 30 50

Silicon content (g/l) 1.34 1.59 0.41 0.12 0.15 0.35

Desiliconizing agent of the present invention is formed by an industry pair product, and cheap, the silica removal process is simple, its essence is in digestion process the dissolves silicon in the black liquor is transferred on the slurry, no white residue separation problem.One of potential advantages of the present invention are that desiliconizing agent contains a certain amount of Na ₂O and K ₂O helps boiling joint alkali; Another prior potential advantages of the present invention are to be not enough to keep out a series of screening-washing process that slurry also need experience attached to the absorption affinity of the siallitization thing on the slurry before manufacturing paper with pulp.Through washing and screening several times, the silicone content on the slurry moves closer to again in the slurry silicon content of silica removal process gained not.

Embodiment 1: 1. standard sulphate cook condition

Add 1 kilogram of over dry wheat straw in 15lZQS type electric cooking pot, alkali charge 15%(is in NaOH), sulphidity 15%, liquor ratio 1: 6.Cooking liquor preparation: earlier with 132 gram NaOH and 67.5 gram Na ₂S9HO is dissolved in the 2700ml hot water, and rare then cooking liquor that extremely needs is made a gesture of measuring.Temperature control program: idle running 5min; Be warming up to pressure 2kg/cm with 133 ℃/hr speed ², little steam bleeding to 105 ℃ continues to be warming up to 155 ℃ with 33-40 ℃/hr speed, is incubated 2 hours.

Treat that slurry is cool slightly, separate black liquor and slurry, get black liquor 2.21, sample analysis with cloth bag.Black liquor PH11.29,20 ℃ of Be ' 8.65, TS140.86g/l; Sulfate ash 39.11g/l, total alkali 36.04g/l, SiO ₂3.07g/l, CaO+MgO 7.93mg/l, total iron 13.7mg/l, Al0.18mg/l, VIE value 4.07mg/l, 29 ℃ of viscosity 6.15Cp, calorific value 3650kCal/kg.

The slurry that cloth bag separates is taken a sample and is surveyed unscreened yield, after further washing and screening (water consumption is controlled at 50 liters), and sampling survey sundry item.Pulp yield 54.5%, permanganate number 10.0,16.6 ° of SR of beating degree, ash 9.38%, SiO ₂5.69%, CaO+MgO 0.214%, total iron 0.056%, Al0.038%.

2. the synchronous silica removal process of sulfate

The cooking liquor preparation is dissolved in the mixing desiliconizing agent (mixing ratio A: H: M=100: 4: 2) below 25 grams, 30 orders in the cooking liquor then with example 1, and other conditions of cooking, temperature control, sampling control are all with example 1.The black liquor PH11.80 that obtains, 20 ℃ of Be ' 8.64, TS142.76g/l, sulfate ash 34.28g/l, total alkali 33.96g/l, SiO ₂0.32g/l, CaO+MgO 22.24mg/l, total iron 17.5mg/l, Al0.37mg/l, VIE value 5.088mg/l, 29 ℃ of viscosity 6.00Cp, calorific value 3775kCal/kg.

Unscreened yield 56.5%, sieve back slurry permanganate number 8.77,19.0 ° of SR of beating degree, ash 10.53%, SiO ₂5.51%, CaO+MgO 0.136%, total iron 0.038%, and Al 0.844%.

Embodiment 2: the 1. inferior sodium method of standard base (SB) formula conditions of cooking

Cooking liquor preparation: with 132 gram NaOH, 40 gram Na ₂S9H ₂O and 14.5 gram sodium sulfites are dissolved in the 2700ml hot water, and rare then cooking liquor that extremely needs is made a gesture of measuring.Obtain like this add alkali number and sulphidity still for 15%(in NaOH).

Other conditions of cooking are constant.

The black liquor PH11.29 that obtains, 20 ℃ of Be ' 9.2, sulfate ash 40.35g/l, total alkali 36.09g/l, SiO ₂4.26g/l, CaO+MgO 10.66mg/l, total iron 26.5mg/l, Al0.19mg/l, VIE value 2.13mg/l, 29 ℃ of viscosity 5.15Cp, calorific value 3558kCal/kg.

Unscreened yield 50.0%, sieve back slurry permanganate number 13.67,18.5 ° of SR of beating degree, ash 10.78%, SiO ₂7.17%, CaO+MgO 0.194%, total iron 0.059%, Al0.088%.

2.: the synchronous silicon removing process of the inferior sodium method of alkali formula

Add 30 grams and mix desiliconizing agent, mixing ratio A: H: M=100: 0: 0, other conditions were with example 3.

The black liquor PH11.30 that obtains, 20 ℃ of Be ' 9.3, sulfate ash 36.72g/l, total alkali 35.88g/l, SiO ₂0.84g/l, CaO+MgO 16.13mg/l, total iron 27.5mg/l, Al0.41mg/l, VIE value 3.47mg/l, 29 ℃ of viscosity 6.10Cp, calorific value 3749kCal/kg.

Unscreened yield 56.3%, sieve back slurry permanganate number 13.79,18.0 ° of SR of beating degree, ash 13.49%, SiO ₂7.79%, CaO+MgO 0.148%, total iron 0.058%, Al0.425%.

Claims

1, a kind of non-wood fibrous raw material alkaline pulping black liquor silicon removing method, it is characterized in that adopting the leftover bits and pieces, the C lime stone that contain paying of aluminium oxide or aluminium hydroxide in the A aluminum smelting industry and contain alkaline matter in product, the B chlorine industry to mix and make desiliconizing agent, the mixing ratio of three kinds of materials (weight ratio) is A: H: M=100: 0-10: 0-5, desiliconizing agent is added in joining the alkali groove or directly be added in the digester before the boiling, and non-wood-fiber per ton adds desiliconizing agent 10-50 kilogram.

2, non-wood-fiber alkaline pulping black liquor silicon removing method according to claim 1 is characterized in that it is more than 80 ℃ that desiliconizing agent is added in the heating-up temperature of joining in the alkali groove.