CN100532266C - Technique for producing hydrate alumina and silicic acid with coal ash - Google Patents

Technique for producing hydrate alumina and silicic acid with coal ash Download PDF

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CN100532266C
CN100532266C CNB2007101332165A CN200710133216A CN100532266C CN 100532266 C CN100532266 C CN 100532266C CN B2007101332165 A CNB2007101332165 A CN B2007101332165A CN 200710133216 A CN200710133216 A CN 200710133216A CN 100532266 C CN100532266 C CN 100532266C
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CN101172634A (en
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刘成长
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Xinyang Green Beijing Energy Technology Co ltd
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Abstract

A process method of utilizing pulverized coal to produce aluminium hydroxide and silicic acid belongs to the field of developing and utilizing method of aluminium silicate mineral in chemical industry. The invention aims at solving the defects of the prior methods, including mere utilization of the alumina component in the pulverized coal, low extraction yield of 60 to 85 percent, abandon of the main component silicon dioxide, high energy consumption, high cost, deprecation of main component and secondary pollution caused by undone recycling of the washing liquid after water washing for multiple times. The invention relies on the principle of pure alkali and sodium hudroxide recirculation and adopts sintering technique. After resolving the pure alkali, resolving the sodium hudroxide, hydrolyzing, carbonizing and causticizing, the alumina of 95 percent and the silicon dioxide of 90 percent are extracted at the same time to produce aluminium hydroxide, silicic acid and calcium carbonate. The technique processes are simple and the production period of the products is short. The carbon dioxide in the raw material pure alkaline, the sodium hudroxide and the fume in the flue, as well as the residual heat and the washing liquid are recycled and reused, in order to bring down the production cost. The product produced by the invention is applicable for the industries such as paper making, printing ink, printing and dyeing as well as medicine, and the further-developed product can be used in the industries of petrochemicity, rubber and plastic, etc.

Description

Utilize flyash to produce aluminium hydroxide and silicic acid processing method
Utilize flyash to produce aluminium hydroxide and silicic acid processing method.
Technical field:
The method that the present invention relates to utilize the chemical development of aluminium silicate mineral to utilize, particularly a kind of processing method of utilizing flyash to produce aluminium hydroxide and silicic acid.
Background technology:
According to the limit bright prosperous, separate strong, Zhao Youcai and in " coal solid changing waste into resources technology " (Chemical Industry Press's in May, 2005 first version) book, claim: national flyash output was 1.6 hundred million tons in 2000, take up an area of 500,000 mu, add 1,100,000,000 tons of flyash of stock over the years, national flyash in 2000 accumulates total amount and reaches 12.5 hundred million tons.Since the increase of thermal power output, by the end of the end of the year 2006, nearly 2,000,000,000 tons in the flyash that whole nation accumulative total is accumulated.The essentially consist of flyash is an aluminosilicate, mainly be aluminum oxide and silicon-dioxide, two components total accounts for 75-92%, wherein aluminum oxide accounts for 23-38%, silicon-dioxide generally accounts for more than 50%, other contains the oxide compound of elements such as small amounts of iron, calcium, magnesium, and each components contents is different because of the place of production of coal.Extracting Chemicals from trade waste flyash, turn waste into wealth, improve environment, is countries in the world, the important industry policy of China especially.
People such as Sun Yazhen CN1095689.1994 and Chen Jianlin the 14th page of 1994 the 4th phase " environment Leader " publish the article (documents 1) propose with 50-60% sulfuric acid immersion flyash 12-14 hours, 100 ℃ of heating 2-4 hours, filtered while hot, the repetitive scrubbing filter cake is to neutral, discard filter cake, the filtrate heating is concentrated into 15-20 degree Beaume crystallisation by cooling again, and suction filtration obtains the Tai-Ace S 150 crystal.This documents 1 adopts acidleach flyash technology to obtain the Tai-Ace S 150 product, and the extraction yield of aluminum oxide has only 60-65%, and the main components silica of the another kind in the flyash is not utilized, and the economic worth of technology is not high.
Xie Ying the 54th page of 1992 the 3rd phase " total utilization of PCA " publish the article (documents 2) propose flyash is mixed stirring and is heated to boiling with caustic soda soln, insulated and stirred for some time again, filter, discard filter cake, filtrate is added water or feed carbonic acid gas, add volatile salt, obtain aluminum hydroxide precipitation, more after filtration, filter cake oven dry is obtained aluminium hydroxide.The wet processing that this documents 2 adopts, the extraction yield of aluminum oxide also has only about 70%, and another main components silica is not utilized yet in the flyash.
Han Huaiqiang, Jiang Tingda are in the 177-179 page of proposition lime sinter process of " utilization of fly ash technology " (Chemical Industry Press's first version in January calendar year 2001) (documents 3), flyash is mixed the back to be burnt till at 1320-1400 ℃ with limestone powder, make aluminum oxide change into sodium aluminate and calcium aluminate, through grog from efflorescence, yellow soda ash stripping, milk of lime desiliconization waste, carbon dioxide carbonization, extract aluminium hydroxide, again with aluminium hydroxide 1200 ℃ of calcinings, obtain aluminum oxide.The waste residue that discards during desiliconization is used to produce cement.It is 80-85% that Liu Xiaobo proposes the rational alumina extraction ratio of lime sinter process technology the 210-213 page of 1999 the 2nd phase " ACTA Scientiae Circumstantiae ".This documents 3 adopts lime sinter process, and the extraction yield of aluminum oxide is greatly improved in the powdered coal ash, but also can only reach 85%; Simultaneously, in the flyash another more main ingredient silicon-dioxide just be used to produce cement still not by high value added utilization as waste residue, the economic worth of silica component is underutilized.
In sum, there is following deficiency in documents 1,2,3:
1, all only the alumina component in the flyash is utilized, also can only reach 60-85% to the extraction yield of aluminum oxide, so the utilization ratio of resource is all lower, only has been equivalent to utilize about 20-30% of powdered coal ash total amount; When alumina content in the raw material powder coal ash is low, the raw material powder coal ash can not utilize.
2, to another the main components silica in the flyash, abandoned in the documents 1,2, just be used for the cement of production low value in the documents 3 as waste residue, silica component does not obtain high value added utilization.
3, all occurred in utilizing the flyash process because of the energy consumption height, life cycle of the product is long, and the powdered coal ash utilization ratio is lower in addition, makes the cost of unit output product increase the problem that production cost is difficult to reduce.
4, all need in the production technique repeatedly to wash with water, and washings fails to be recycled, and has not only expended a large amount of valuable water resourcess, add the abandoning of main component silicon-dioxide of flyash in the documents 1,2, all cause second environmental pollution.
This shows that studying a kind of resource utilization height, utilization of resources added value height, production cost is low, production process does not have secondary pollution fly ash development, to utilize method be necessary.
Summary of the invention:
The objective of the invention is to overcome the deficiencies in the prior art, develop that a kind of resource utilization height, utilization of resources added value height, production cost are low, production process does not have the fly ash development of secondary pollution to utilize method again, particularly a kind of processing method of utilizing flyash to produce aluminium hydroxide and silicic acid.
The object of the present invention is achieved like this: a kind of processing method of utilizing flyash to produce aluminium hydroxide and silicic acid, be characterised in that utilization soda ash and caustic soda round-robin principle, adopt sintering process technology, melt-caustic soda alkali fusion-hydrolysis-carbonization-causticization by soda ash alkali, realize extracting simultaneously aluminum oxide and silicon-dioxide in the flyash, produce aluminium hydroxide and silicic acid and lime carbonate.
Description of drawings:
Fig. 1 is a technological principle synoptic diagram of the present invention, and Fig. 2 is the concrete Production Flow Chart synoptic diagram of implementing of the present invention.
As shown in fig. 1:
1, soda ash alkali melts: flyash and light ash in the circulation are carried out alkali after mixing melt processing.
2, shrend: alkali melted handle the molten mass grog obtain and take advantage of high temperature and carry out shrend rapidly, obtain the solid fine grain material.Shrend liquid is used to dissolve the slurry that road wet-milling operation in back obtains.
3, wet-milling: the solid fine grain material that shrend is obtained carries out wet-milling, obtains dense thick slurry.
4, slurry dissolving: the underflow material that wet-milling is obtained dilutes, dissolves, and obtains filter cake and filtrate.Filtrate input back road dilution hydrolyzing process is produced aluminium hydroxide, and filter cake enters down road caustic soda alkali fusion procedure.
5, caustic soda alkali fusion: the filter cake that the slurry dissolving is obtained dissolves with the concentrated caustic solution in the circulation, obtains the underflow material; The underflow material is carried out heat treated, obtain dry powder.
6, dry powder dissolving: the dry powder that the caustic soda alkali fusion is obtained dissolves.After the dissolving, filter, obtain filter cake and filtrate.Filtrate input back road dilution hydrolyzing process is produced aluminium hydroxide, and filter cake enters down road caustic soda stripping operation.
7, caustic soda stripping: the filter cake that the dry powder dissolving is obtained carries out stirring and dissolving with the concentrated caustic solution in the circulation.After the dissolving, filter, obtain filter cake and filtrate.Filtrate input back road dilution hydrolyzing process is produced aluminium hydroxide, and filter cake is through washing as filter residue.
8, dilution hydrolysis: the filtrate that the dissolving of front slurry, dry powder dissolving and caustic soda stripping are obtained merges, and dilutes hydrolysis.After the hydrolysis, filter, obtain filter cake and filtrate.Filter cake is aluminium hydroxide through washing, and the filtrate input is road first carbonation process down.
9, first carbonization: dilution water is separated the filtrate that obtains, carry out the carbonating processing first time with carbon dioxide.After first carbonization finishes, filter, obtain filter cake and filtrate.Filter cake is aluminium hydroxide through washing; The filtrate input is road second carbonation process down.
10, second carbonization:, carry out the carbonating processing second time with carbon dioxide with the filtrate that first carbonization obtains.After second carbonization finishes, filter, obtain filter cake and filtrate.Filter cake is silicic acid through washing; Filtrate is imported down road the 3rd carbonation process and causticization operation respectively.
11, the 3rd carbonization: with the filtrate that second carbonization obtains, get the amount that needs, carry out carbonating processing for the third time with carbon dioxide.After the 3rd carbonization finishes, filter, obtain filter cake and filtrate.Filtrate is used as the feed liquid of next batch the 3rd carbonization again; Filter cake is a sodium bicarbonate, enters down the road drying process.
12, drying: the filter cake sodium bicarbonate with the 3rd carbonization obtains, carry out drying treatment, obtain light ash and dust-laden tail gas.Dust-laden tail gas discharges through after the purifying treatment; The light ash circulation is melted operation for slubbing soda ash alkali and is used.
13, causticization: with the filtrate that second carbonization obtains, get the amount that needs, carry out causticization and handle.After causticization finishes, filter, obtain filter cake and filtrate.Filter cake is lime carbonate through washing; Filtrate is dilute solution of sodium hydroxide, obtains concentrated caustic solution through concentrating.The concentrated caustic solution circulated is used for front caustic soda alkali fusion, caustic soda stripping two procedures.
Embodiment:
In conjunction with Fig. 2, the present invention is so further realization:
Flyash among described Fig. 2 be meant with granularity be 100-200 purpose flyash dry ashes as the raw material powder coal ash, wherein aluminum oxide and dioxide-containing silica are all without limits.
Soda ash alkali among described Fig. 2 melts and is meant 100-200 purpose flyash and light ash according to quality than flyash: light ash=prepare burden at 1: 0.5-2.6, concrete consumption is according to mol ratio Al 2O 3: Na 2CO 3=1: 1 and SiO 2: Na 2CO 3=1: 0.4-2.3 sums are calculated, and react 40-60 minutes under 1050-1450 ℃ of temperature, keep drop temperature more than 1000 ℃.
As shown in Figure 2, the high-temperature flue gas that produces during soda ash alkali melts carries out heat exchange with clean normal temperature air and water at first respectively to be handled: high-temperature flue gas is through the air heat exchange, the normal temperature air of cleaning heated respectively obtain 400-780 ℃ of clean hot air with 300-400 ℃ of two kinds of temperature, the high-temperature flue gas temperature reduces, and becomes warm stack gas in 500-600 ℃; In the water heat exchange again of warm stack gas, obtain 60-80 ℃ hot water, middle temperature effluent gas temperature is reduced to below 200 ℃.Low temperature flue gas below 200 ℃ obtains carbonated normal temperature clean flue gas through washing, purifying treatment.
The heating that 400-780 ℃ clean hot air is used for caustic soda alkali fusion technology concentrates and cures drying;
300-400 ℃ clean hot air is used for the natrii bicarbonas filter cake drying process;
60-80 ℃ hot water is used for the filter cake washing of each corresponding technology;
Carbonated normal temperature clean flue gas is used for first carbonization, second carbonization, the 3rd carbonization technique.
By to heat exchange utilization and purifying treatment in the stack gas, realized the utilization again of used heat and waste gas.
Shrend among described Fig. 2 is meant melts the high-temperature fusion body grog that technology generates with alkali, melts the furnace discharge mouth from alkali and flows out automatically, enters cooling suddenly in the water quenching pool that fills washings, and high temperature chamotte is fragmented into 1-5 millimeters fine particle.Shrend liquid is used for road, back slurry dissolution process.
Wet-milling among described Fig. 2 is meant that the fine granules that the water quenching technology section is obtained takes out from water quenching pool, add washings and carry out wet-milling, is ground to more than fineness 100 orders, obtains dense thick slurry.
Slurry dissolving among described Fig. 2 is meant that the dense thick slurry of solid phase fineness more than 100 orders that wet-milling is obtained dilutes with shrend liquid and washings.During dilution, active Na in the control solution 2O 〉=200 grams per liters stirred 20-30 minutes under natural temperature, filtered as early as possible in 2 hours.Active Na 2The Na that the O amount drops into when melting according to alkali 2CO 370-75% of amount is calculated.
Caustic soda alkali fusion among described Fig. 2 is meant that slurry dissolution process section is filtered the filter cake that obtains dissolves with the concentrated caustic solution stirring of concentration more than 50%; After the dissolving, with mixing solutions with 400-780 ℃ the clean hot air that obtains through the stack gas heat exchange heat concentrated, cure drying, become dry powder until material.The caustic soda alkali fusion time is 40-60 minutes.During stirring and dissolving, the concentrated caustic solution amount of adding is mixed SiO in the solution of back according to filter cake with caustic soda 2: Na 2O=1: 1.2-1.5 calculate.
Dry powder dissolving among described Fig. 2 is meant that the dry powder that will obtain through caustic soda alkali fusion process section dissolves with washings.During the dry powder dissolving, Na in the solution of control dissolving back 2Soluble SiO in O 〉=300 grams per liters, the dry powder 2Theoretical Calculation concentration after dissolving≤200 grams per liters, dissolution time are 20-30 minutes.After the dry powder dissolving, at 4 hours inner filtrations.
Caustic soda stripping among described Fig. 2 is meant filtering the filter cake that obtains through dry powder dissolution process section, uses the concentrated caustic stirring and dissolving of concentration more than 50% again.During the filter cake dissolving, Na in the control solution 2O 〉=390 grams per liters, about 20-30 minutes of dissolution time.After the filter cake dissolving, filter, the filter cake that obtains with through in 60-80 ℃ of hot washes obtaining of warm stack gas heat exchange to PH=8-9, washings is concentrated to be used for recycle.Filter cake after the washing merges with the causticization residue as filter residue, is used for that the sewage after the washing stack gas is carried out flocculating and purifying and handles.
Dilution hydrolysis among described Fig. 2 is meant filtrate that the slurry dissolution process after the wet-milling of front, dry powder dissolution process and upper track caustic soda stripping operation after-filtration are obtained concentrating, with washings dilute, heating hydrolysis.During hydrolysis, total Na in the control solution 2O% 〉=8.5%; SiO 2Theoretical Calculation concentration≤65 grams per liters; NaAlO 2Theoretical Calculation concentration≤0.5M; 85-87 ℃ of hydrolysis temperatures, 20-30 minutes time.After the hydrolysis, filter, 60-80 ℃ of hot washes that the filter cake that obtains obtains with warm stack gas heat exchange in passing through obtain aluminium hydroxide to PH=7; Washings is concentrated and is used for recycle.Filtrate enters down road first carbonation process.
First carbonization among described Fig. 2 is meant the filtrate that dilution hydrolysis after-filtration is obtained, and carries out the carbonating processing first time with carbonated normal temperature clean flue gas.During carbonization, gas concentration lwevel 〉=18%, 60-80 ℃ of starting temperatures; Pressure 0.25-0.3MPa; 40 ℃ of terminal temperatures, PH=10.8-11; Carbonization time 1 hour.After first carbonization finished, at normal pressure, 20 minutes after-filtration of about 40 ℃ of following ageings, 60-80 ℃ of hot washes that the filter cake that obtains obtains with warm stack gas heat exchange in passing through obtained aluminium hydroxide to PH=7; Washings is concentrated and is used for recycle.Filtrate enters down road second carbonation process.
Second carbonization is meant the filtrate that the first carbonization after-filtration is obtained among described Fig. 2, carries out the carbonating processing second time with carbonated normal temperature clean flue gas again.During carbonization, gas concentration lwevel 〉=18%, 60-80 ℃ of starting temperatures; Pressure 0.25-0.3MPa; 40 ℃ of terminal temperatures, PH=8.7-9; Carbonization time 1 hour.Second carbonization at normal pressure, 20 minutes after-filtration of about 40 ℃ of following ageings, obtains filter cake and yellow soda ash filtrate after finishing.Filter cake with through in 60-80 ℃ of hot washes obtaining of warm stack gas heat exchange to the PH=7, obtain silicic acid; Washings is concentrated and is used for recycle.A yellow soda ash filtrate part enters down road the 3rd carbonation process, and another part enters the causticization operation of back.
The 3rd carbonization among described Fig. 2 is meant that the yellow soda ash filtrate that the second carbonization after-filtration is obtained gets the amount that needs and carry out carbonating processing for the third time with carbonated normal temperature clean flue gas again.During carbonization, CO 2〉=18%, stock liquid Na 2CO 3Concentration=20%～22%, density d=1.19-1.21g/cm 370-80 ℃ of starting temperatures; Pressure 0.25-0.3MPa; 39-50 ℃ of carbonization terminal temperatures, terminal point solution density d=1.099-1.107g/cm 3, carbonization time is 1.5-2 hours.After the 3rd carbonization finished, with water quench crystallization and filtration under the normal temperature, filter cake was a sodium bicarbonate crystal, enters down the road drying process under normal pressure.
Filtrate being contained the saturated solution of sodium bicarbonate of yellow soda ash, is used for earlier the dried tail gas of sodium bicarbonate in the following road drying process is carried out spray washing, removes the sodium carbonate dust in the tail gas.Solution behind the spray merges with the yellow soda ash filtrate that the next batch second carbonization after-filtration obtains again, is reused for the 3rd carbonization of next batch; Tail gas behind the spray washing directly discharges.
Drying among described Fig. 2 is meant the filter cake sodium bicarbonate that the 3rd carbonization after-filtration is obtained, and carries out drying treatment with 300-400 ℃ the clean hot air that obtains through the stack gas heat exchange, obtains the circulation of soda ash yellow soda ash dry powder and is used for soda ash alkali and melts process section.
Causticization among described Fig. 2 is meant that the yellow soda ash filtrate that the second carbonization after-filtration is obtained gets the amount that needs and carry out causticization with unslaked lime and handle, and obtains caustic soda sodium hydroxide, and by-product goes out lime carbonate.During causticization, Na 2CO 3Concentration=14%～16%, 90-105 ℃ of temperature, 1-2 hours causticization time.After causticization finishes, filter, obtain filter cake and sodium hydroxide filtrate.Filter cake with through in 60-80 ℃ of hot washes obtaining of warm stack gas heat exchange to PH=7, obtain lime carbonate; Washings is concentrated and is used for recycle.After the sodium hydroxide filtrate evaporation concentration to 50%, use for caustic soda alkali fusion and caustic soda dissolving-out process section as the concentrated caustic circulation.
The filter residue that obtains after the waste residue of causticization and the front caustic soda dissolving-out process section filter cake washing merges, and is used for that the sewage after the washing stack gas is carried out flocculating and purifying and handles.The clear water circulation that obtains after the purifying treatment is used for follow-up flue gas scrubbing, has realized the washes circulation.
Be the principles of chemistry in each technical process among Fig. 1, Fig. 2 below:
Soda ash alkali melts:
Na 2CO 3+SiO 2→Na 2SiO 3+CO 2↑
Na 2CO 3+Al 2O 3→NaAlO 2+CO 2↑
NaAlO 2+Na 2SiO 3→Na 2O·Al 2O 3·2SiO 2
Na 2CO 3+Fe 2O 3→NaFeO 2+CO 2↑
NaFeO 2+Al 2O 3→NaAlO 2+Fe 2O 3
CaO+SiO 2→2CaO·SiO 2
CaO+Al 2O 3→CaO·Al 2O 3
CaO+Fe 2O 3→2CaO·Fe 2O 3
CaO+TiO 2→CaO·TiO 2
Na 2CO 3+TiO 2→Na 2O·TiO 2+CO 2↑
Na 2CO 3+SiO 2+CaO→Na 2O·CaO·SiO 2+CO 2↑
CaO+Na 2O·Al 2O 3·2SiO 2→NaAlO 2+2CaO·SiO 2
2CaO·SiO 2+TiO 2→CaO·TiO 2+SiO 2
MgO+SiO 2→MgO·SiO 2
MgO+TiO 2→MgO·TiO 2
MgO+CaO+Fe 2O 3→MgO·2CaO·Fe 2O 3
The slurry dissolving:
NaAlO 2+2H 2O→Al(OH) 3↓+NaOH
NaFeO 2+2H 2O→Fe(OH) 3↓+NaOH
Na 2O·Al 2O 3·2SiO 2+NaOH→NaAlO 2+Na 2SiO 3+H 2O
The caustic soda alkali fusion:
Na 2O·Al 2O 3·2SiO 2+NaOH→NaAlO 2+Na 2SiO 3+H 2O
Al(OH) 3+NaOH→NaAlO 2+H 2O
Fe(OH) 3+NaOH→NaFeO 2+2H 2O
The dry powder dissolving:
NaAlO 2+2H 2O→Al(OH) 3↓+NaOH
NaFeO 2+2H 2O→Fe(OH) 3↓+NaOH
The caustic soda stripping:
Al(OH) 3+NaOH→NaAlO 2+H 2O
The dilution hydrolysis:
NaAlO 2+2H 2O→Al(OH) 3↓+NaOH
First carbonization:
2NaOH+CO 2→Na 2CO 3+H 2O
NaAlO 2+CO 2+H 2O→Na 2CO 3+Al(OH) 3↓
2Na 2SiO 3+CO 2+H 2O→Na 2CO 3+2NaHSiO 3
Second carbonization:
2NaHSiO 3+CO 2+H 2O→Na 2CO 3+2H 2SiO 3↓
The 3rd carbonization:
Na 2CO 3+CO 2+H 2O→2NaHCO 3↓
Dry:
NaHCO 3→Na 2CO 3+CO 2↑+H 2O↑
Causticization:
Na 2CO 3+CaO+H 2O→CaCO 3↓+2NaOH
The present invention has received following effect through practical probation:
1, the resource utilization height of flyash. Compare with documents 1,2,3, the present invention has not only utilized and has accounted for flyash The aluminium oxide of raw material total amount about 30%, and utilized simultaneously and account for the silica component of powdered coal ash more than 50%, be suitable for Exploitation in various fly ash; More than the extraction rate reached to 95% of aluminium oxide, more than the extraction rate reached to 90% of silica.
2, the added value height of the utilization of resources. Compare with documents 1,2,3, use the molten and molten technology of alkali of known acid, Carry out further deep processing by aluminium hydroxide and the silicic acid that the present invention is obtained, be easy to obtain A wide selection of colours and designs, specification is various The various aluminium salt of high added value and the chemical products such as silicate and aluminium oxide, aluminate, precipitated silica, silica gel. Skill The commercial value height that art is used.
3, product cost is low.Compare with documents 1,2,3, the present invention adopts alkali process, and technical process is succinct, and life cycle of the product is short, as long as 4-6 hours; Product yield height; The recycle and reuse of raw material soda ash and caustic soda, and to the recycling of the carbonic acid gas in the stack gas, waste heat, washings makes resulting aluminium hydroxide and silicic acid cost all reduce significantly than other processing method production costs both at home and abroad.
4, cleaner production.Compare with documents 1,2,3, technological process of the present invention has realized the material closed cycle, and production process does not have secondary pollution to environment.
The aluminium hydroxide that the invention process obtains, silicic acid and calcium carbonate product and use various aluminium salt, aluminate, aluminum oxide, silicate, white carbon black, the silica gel product that known acid is molten, the molten technology of alkali obtains by aluminium hydroxide and silicic acid can be that industries such as printing ink, papermaking, printing and dyeing, weaving, medicine, grease, catalyzer, plastics, rubber, daily use chemicals, oil are used.

Claims (9)

1, a kind of processing method of utilizing flyash to produce aluminium hydroxide and silicic acid, it is characterized in that using soda ash and caustic soda round-robin principle, adopt sintering process technology, melt-caustic soda alkali fusion-hydrolysis-carbonization-causticization by soda ash alkali, realize extracting simultaneously aluminum oxide and silicon-dioxide in the flyash, produce aluminium hydroxide and silicic acid and lime carbonate:
(1) soda ash alkali melts: flyash and light ash in the circulation are carried out alkali after mixing melt processing;
(2) shrend: alkali melted handle the molten mass grog obtain and take advantage of high temperature and carry out shrend rapidly, obtain the solid fine grain material; Shrend liquid is used to dissolve the slurry that road wet-milling operation in back obtains;
(3) wet-milling: the solid fine grain material that shrend is obtained carries out wet-milling, obtains dense thick slurry;
(4) slurry dissolving: the underflow material that wet-milling is obtained dilutes, dissolves, and after the dissolving, filters, and obtains filter cake and filtrate, and filtrate input back road dilution hydrolyzing process is produced aluminium hydroxide, and filter cake enters down road caustic soda alkali fusion procedure;
(5) caustic soda alkali fusion: the filter cake that the slurry dissolving is obtained dissolves with the concentrated caustic solution in the circulation, obtains the underflow material; The underflow material is carried out heat treated, obtain dry powder;
(6) dry powder dissolving: the dry powder that the caustic soda alkali fusion is obtained dissolves, and after the dissolving, filters, and obtains filter cake and filtrate, and filtrate input back road dilution hydrolyzing process is produced aluminium hydroxide, and filter cake enters down road caustic soda stripping operation;
(7) caustic soda stripping: the filter cake that the dry powder dissolving is obtained carries out stirring and dissolving with the concentrated caustic solution in the circulation; After the dissolving, filtration obtains filter cake and filtrate, and filtrate input back road dilution hydrolyzing process is produced aluminium hydroxide, and filter cake is through washing as filter residue;
(8) dilution hydrolysis: the filtrate that the dissolving of front slurry, dry powder dissolving and caustic soda stripping are obtained merges, and dilutes hydrolysis; After the hydrolysis, filter, obtain filter cake and filtrate, filter cake is aluminium hydroxide through washing, and the filtrate input is road first carbonation process down;
(9) first carbonizations: dilution water is separated the filtrate that obtains, carry out the carbonating processing first time with carbon dioxide; After first carbonization finishes, filter, obtain filter cake and filtrate, filter cake is aluminium hydroxide through washing, and the filtrate input is road second carbonation process down;
(10) second carbonizations:, carry out the carbonating processing second time with carbon dioxide with the filtrate that first carbonization obtains; After second carbonization finishes, filter, obtain filter cake and filtrate, filter cake is silicic acid through washing, and filtrate is imported down road the 3rd carbonation process and causticization operation respectively;
(11) the 3rd carbonizations: with the filtrate that second carbonization obtains, get the amount that needs, carry out carbonating processing for the third time with carbon dioxide; After the 3rd carbonization finishes, filter, obtain filter cake and filtrate, as the feed liquid of next batch the 3rd carbonization, filter cake is a sodium bicarbonate to filtrate, enters down the road drying process again;
(12) drying: the filter cake sodium bicarbonate with the 3rd carbonization obtains, carry out drying treatment, obtain light ash and dust-laden tail gas; Dust-laden tail gas discharges through after the purifying treatment, and the light ash circulation is melted operation for slubbing soda ash alkali and used;
(13) causticization: with the filtrate that second carbonization obtains, get the amount that needs, carry out causticization and handle; After causticization finishes, filter, obtain filter cake and filtrate, filter cake is lime carbonate through washing, and filtrate is dilute solution of sodium hydroxide, obtains concentrated caustic solution through concentrating, and circulation is used for front caustic soda alkali fusion, caustic soda stripping two procedures.
2, method according to claim 1, it is characterized in that describedly flyash and light ash in the circulation are carried out alkali after mixing melting processing, be with 100-200 purpose flyash and light ash according to quality than flyash: light ash=prepare burden at 1: 0.5-2.6, under 1050-1450 ℃ of temperature, reacted 40-60 minutes, keep drop temperature more than 1000 ℃.
3, method according to claim 1, it is characterized in that described slurry dissolving: the underflow material that wet-milling is obtained dilutes, dissolves, and after the dissolving, filters, be meant that the dense thick slurry of solid phase fineness more than 100 orders that wet-milling is obtained dilutes, active Na in the control solution 2O 〉=200 grams per liters was at 2 hours inner filtrations.
4, method according to claim 1 is characterized in that described caustic soda alkali fusion: the filter cake that the slurry dissolving is obtained dissolves with the concentrated caustic solution in the circulation, obtains the underflow material; The underflow material is carried out heat treated, obtain dry powder, be meant that slurry dissolution process section is filtered the filter cake that obtains dissolves with the concentrated caustic solution stirring of concentration more than 50%, the caustic soda soln consumption mixes SiO in the solution of back according to filter cake with caustic soda 2: Na 2O=1: 1.2-1.5 calculate; After the dissolving, mixing solutions is carried out heat treated at 400-780 ℃, become dry powder until material.
5, method according to claim 1, it is characterized in that described dry powder dissolving: the dry powder that the caustic soda alkali fusion is obtained dissolves, and after the dissolving, filters, and is meant that the dry powder that will obtain through the caustic soda alkali fusion dissolves, Na in the control solution 2Soluble SiO in O 〉=300 grams per liters, the dry powder 2Theoretical Calculation concentration after dissolving≤200 grams per liters, dry powder dissolving back was at 4 hours inner filtrations.
6, method according to claim 1, it is characterized in that described caustic soda stripping: the filter cake that the dry powder dissolving is obtained carries out stirring and dissolving with the concentrated caustic solution in the circulation, is meant to use the concentrated caustic stirring and dissolving of concentration more than 50% again with filtering the filter cake that obtains through the dry powder dissolution process; During the filter cake dissolving, Na in the control solution 2O 〉=390 grams per liters.
7, method according to claim 1, it is characterized in that described dilution hydrolysis: the filtrate that the dissolving of front slurry, dry powder dissolving and caustic soda stripping are obtained merges, dilute hydrolysis, be meant and concentrate, dilute, heating hydrolysis filtering the filtrate obtain in front slurry dissolution process, dry powder dissolution process and the caustic soda stripping operation; During hydrolysis, total Na in the control solution 2O% 〉=8.5%, SiO 2Theoretical Calculation concentration≤65 grams per liters, NaAlO 2Theoretical Calculation concentration≤0.5M, 85-87 ℃ of hydrolysis temperatures.
8, method according to claim 1, it is characterized in that described first carbonization: dilution water is separated the filtrate that obtains, carry out the carbonating processing first time with carbon dioxide, be meant when filtrate that dilution hydrolysis after-filtration is obtained is carried out first time carbonating processing with carbon dioxide, gas concentration lwevel 〉=18%, 60-80 ℃ of starting temperatures, pressure 0.25-0.3MPa, 40 ℃ of terminal temperatures, PH=10.8-11.
9, method according to claim 1, it is characterized in that described second carbonization: the filtrate that first carbonization is obtained, carry out the carbonating processing second time with carbon dioxide, be meant the filtrate that the first carbonization after-filtration is obtained, when carrying out with carbon dioxide that the second time, carbonating was handled again, gas concentration lwevel 〉=18%, 60-80 ℃ of starting temperatures, pressure 0.25-0.3MPa; 40 ℃ of terminal temperatures, PH=8.7-9.
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