CN102476820B - Method for extracting alumina from coal ash through wet process - Google Patents
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Abstract
The invention provides a method for extracting alumina from coal ash through a wet process. The method comprises the following steps: 1, mixing the coal ash, calcium oxide and an alkaline solution, reacting, carrying out flash evaporation, and filtering to obtain an alkaline solution containing sodium aluminate and aluminum removed slag; 2, cooling and crystallizing the alkaline solution obtained in step 1 to obtain a coarse hydrated sodium aluminate crystal and a crystallization mother solution; 3, circulatingly applying the crystallization mother solution obtained in step 2 to a leaching reaction, dissolving the coarse hydrated sodium aluminate crystal with water or a diluted alkaline solution, carrying out silicon removal and seed decomposition to obtain aluminum hydroxide, and calcining aluminum hydroxide to obtain alumina; 4, evaporating the seed-decomposed mother solution, and mixing the evaporated seed-decomposed mother solution with the alkaline solution obtained in the step 1; and 5, carrying out hydrolysis sodium removal on the aluminum removed slag obtained in the step 1 in the diluted alkaline solution, filter-separating, and carrying out multistage countercurrent washing on the sodium removed slag. According to the method, the dissolving-out temperature and the dissolving-out pressure are low, the dissolving-out rate of alumina can reach above 90%, and the content of sodium oxide in the sodium removed slag is less than 1%.
Description
Technical field
A method of extracting aluminum oxide from flyash, particularly a kind of wet method reclaims the method for aluminum oxide from flyash.
Background technology
At present, the production of aluminum oxide mainly be take bauxite as raw material adopts alkaline process production, comprises Bayer process, sintering process and integrated process.China has become alumina producing big country, but bauxite resource degree of protection is low, and resource problem has become the Main Bottleneck of China's sustainable development of alumina industry.
Flyash is one of solid waste producing after coal burning, adds up at present volume of cargo in storage and has reached 2,000,000,000 tons.Develop flyash and produce aluminum oxide, to solving China's bauxite resource problem of environmental pollution in short supply and coal-fired, all have great importance undoubtedly.
The technology that the flyash of take is raw material extraction aluminum oxide has series of patents application.These technology are broadly divided into two classes, one class is alkaline process high-temperature roasting activation, if a kind of coal ash for manufacturing that utilizes of Mengxi Hi-Tech Group Corp., Ltd., Inner Mongolia's invention is for the method (patent No. ZL03131079.6) of aluminum and coproducing cement grog, sintering temperature is more than 1300 ℃, therefore energy consumption is very high, and when sintering, also need to add a large amount of calcium oxide, cause the level of residue extracting after aluminum oxide large.Another kind of is acid system pyrolytic decomposition, if a kind of coal ash for manufacturing that utilizes of Shenyang Aluminium Magnesium Design & Research Inst's invention is for the method (number of patent application 200810011311.2) of Tai-Ace S 150, after flyash mechanical activation, adopt the vitriol oil to decompose, 200 ℃ of left and right of decomposition temperature.The subject matter of acidic process flyash is that corrosive medium is strong, high to equipment material requirement, and spent acid recovery difficulty, easily causes secondary pollution.Just because of the existence of the problems referred to above, restricted the commercial application of flyash extraction aluminum oxide technology.So far not yet find to prepare about flyash alkaline process low temperature document and the granted patent of aluminum oxide series compound.
Summary of the invention
High-temperature operation while the object of the invention is to overcome high-temperature sintering process treated coal ash and the energy consumption that causes is high, operational difficulty and acid system equipment corrosion is serious, the defect that has secondary pollution hidden danger, provide Low Temperature Wet method under a kind of alkaline medium from aluminous fly-ash, to extract the novel method of aluminum oxide, digesting efficiency of alumina is high, level of residue is little, and residue detrimental impurity content is low, easily realize the recycling of waste.
The method of extracting aluminum oxide from flyash provided by the invention, its step is as follows:
(1) batching: the NaOH alkaline solution that is 30%-50% by flyash, calcium oxide and mass percent concentration mixes and joins in reactor, alkaline solution and flyash quality proportioning (8-25): 1, the mass ratio of calcium oxide and flyash is (0.35-0.50): 1;
(2) reaction: the material that step (1) is obtained carries out Leaching reaction in reactor, and temperature is 180-300 ℃, extraction time 0.2-10h, leaches pressure 0.4-6.2MPa, after Leaching reaction completes, obtains slip; By this slurry filtration, obtain alkali lye and dealuminzation slag containing sodium aluminate;
(3) crystallization: the alkali lye containing sodium aluminate adds crystal seed crystallization at 50-100 ℃, obtains aluminate hydrates sodium coarse-grain and crystalline mother solution, and crystalline mother solution is cycled to used in Leaching reaction;
(4) purify and decompose: the aluminate hydrates sodium coarse-grain water that step (3) is obtained or sig water dissolve, and then through desiliconization, seed operation splitting, obtain aluminium hydroxide, then by the aluminium hydroxide calcining obtaining, just making aluminum oxide;
(5) evaporative crystallization: it is 520-600g/L that the seed decomposition nut liquid that step (4) is obtained is evaporated to sodium oxide concentration, then add crystal seed at 50-100 ℃, to carry out crystallization reaction, or join in step (2) gained sodium aluminate solution and carry out together crystallization reaction, crystalline mother solution is for Leaching reaction; Sodium aluminate crystallization mixes with step (4) gained desiliconization sodium aluminate solution after dissolving, and carries out seed decomposition;
(6) de-sodium: the dealuminzation slag that step (2) is obtained joins in dilute alkaline soln, add calcium oxide to take off sodium reaction simultaneously, sig water concentration is 0-80g/L, calcium oxide add-on is the 0-30% of dealuminzation slag amount, liquid-solid mass ratio is (6-10): 1, de-sodium temperature is 80-180 ℃, and the reaction times is 0.5-10h;
(7) washing: de-sodium slag water carries out repeatedly countercurrent washing, and wash temperature is 50-95 ℃, its washings is for the dissolving of step (3) or step (5) aluminate hydrates sodium coarse-grain, and after washing, de-sodium slag is as the raw material of producing material of construction;
Described alkaline solution is the NaOH aqueous solution;
The extraction time of described Leaching reaction is that 0.5-3h is good;
The concentration of lye of described de-sodium reaction is that 40-70g/L is good;
It is good that the temperature of reaction of described de-sodium reaction is 80-95 ℃.
In recovery flyash provided by the invention, the method for aluminum oxide has following obviously superiority:
(1) the present invention adopts low temperature alkaline process treated coal ash, and extraction temperature is 180-300 ℃, and higher temperatures sintering process reduces 900-1000 ℃, and leaching process is carried out under mesolow, can significantly reduce energy consumption; Compared with acid system, significantly reduce the corrodibility to equipment;
(2) Leaching reaction digesting efficiency of alumina of the present invention is up to more than 95%, and resource utilization is high;
(3) high high alkali liquid circulation in the present invention, purify, there is not a large amount of concentration and evaporations in the process such as separated, greatly reduces production energy consumption, simplified production technique, reduced equipment investment, improved industrial operability, reduced production cost;
(4) reaction conditions of the present invention is gentle, and industry is workable.
Accompanying drawing explanation
Fig. 1 has provided the alumina technology route map in low temperature hydrometallurgic recovery flyash.
Embodiment
Embodiment 1
With the aluminum oxide in low temperature hydrometallurgic recovery flyash provided by the invention, somewhere, the Inner Mongol flyash of take is example, and the percentage composition of this flyash principal element oxide compound is as follows:
Al
2o
3siO
2fe
2o
3caO TiO
2na
2o H
2o igloss A/S
41.41 39.54 2.40 3.67 1.38 0.21 6.1 2.81 1.05
Its recycling step is:
The NaOH solution that is 50% with mass percent by flyash mixes and is placed in reactor, alkaline solution and flyash quality proportioning are 10.3: 1, calcium oxide addition is 50% of flyash quality, be warming up to 260 ℃, under 1.6MPa, react 1h, obtain containing the alkali lye of sodium aluminate and the reaction product mixture of dealuminzation slag, reaction product to be mixed is filtered after being cooled to 100 ℃, separation obtains alkaline solution and the dealuminzation slag containing sodium aluminate, now in dealuminzation slag A/S=0.23 (A is quality of alumina per-cent, S is siliconoxide mass per-cent), in flyash, the rate of recovery of aluminum oxide is 81.82%.
By what obtain, containing sodium aluminate alkali solution (filtrated stock), put into crystallization reactor, at 50 ℃, crystallization 6h add 5% crystal seed in the situation that, the crystalline mother solution causticity ratio that filtration obtains is elevated to 28, the causticity ratio of aluminate hydrates sodium crystal is 1.35, then to aluminate hydrates sodium crystal dissolve, desiliconization, kind divide, calcine and can make sandy alumina.
Dealuminzation slag adds water and at 150 ℃, carries out dealkalize, and liquid-solid mass ratio is 10: 1, does not add calcium oxide, reaction 10h, and after dealkalize, solid phase is through countercurrent washing, and wash temperature is 90 ℃.In residue, sodium oxide content is 0.86%.
Embodiment 2
The flyash of embodiment 1 is mixed and is placed in reactor with crystalline mother solution in embodiment 1, mother liquor and flyash quality proportioning are 12.98: 1, calcium oxide addition is 35% of flyash quality, be warming up to 300 ℃, reaction 2h, obtain containing alkali lye, the reaction product mixture of sodium aluminate and dealuminzation slag, after being cooled to 100 ℃, reaction product to be mixed carries out suction filtration, separation obtains alkaline solution and the dealuminzation slag containing sodium aluminate, now in dealuminzation slag A/S=0.02 (A is quality of alumina per-cent, S is siliconoxide mass per-cent), in flyash, the rate of recovery of aluminum oxide is 98%.
By what obtain, containing sodium aluminate alkali solution (filtrated stock), put into crystallization reactor, at 100 ℃, crystallization 10h add 8% crystal seed in the situation that, the crystalline mother solution causticity ratio that filtration obtains is elevated to 25, the causticity ratio of aluminate hydrates sodium crystal is 1.58, then to aluminate hydrates sodium crystal dissolve, desiliconization, kind divide, calcine and can make sandy alumina.
Dealuminzation slag joins in the sodium hydroxide solution of 40g/L, carries out dealkalize at 80 ℃, and liquid-solid mass ratio 6: 1, adds 10% calcium oxide, reaction 10h, and after dealkalize, solid phase is through countercurrent washing, and wash temperature is 90 ℃.In residue, sodium oxide content is 0.98%.
The NaOH solution that is 30% with mass percent by the flyash of embodiment 1 mixes and is placed in reactor, alkaline solution and flyash quality proportioning are 17.45: 1, calcium oxide addition is 60% of flyash quality, be warming up to 300 ℃, under 6.2MPa, react 0.5h, obtain containing the alkali lye of sodium aluminate and the reaction product mixture of dealuminzation slag, after being cooled to 100 ℃, reaction product to be mixed carries out suction filtration, separation obtains alkaline solution and the dealuminzation slag containing sodium aluminate, now in dealuminzation slag A/S=0.35 (A is quality of alumina per-cent, S is siliconoxide mass per-cent), in flyash, the rate of recovery of aluminum oxide is 66.67%.
By what obtain, containing sodium aluminate alkali solution (filtrated stock), put into crystallization reactor, 60 ℃, add 5% crystal seed in the situation that after crystallization 3h, the crystalline mother solution causticity ratio that filtration obtains is elevated to 25, the causticity ratio of aluminate hydrates sodium crystal is 1.60, then to aluminate hydrates sodium crystal dissolve, desiliconization, kind divide, calcine and can make sandy alumina.
Dealuminzation slag joins in the sodium hydroxide solution of 60g/L, carries out dealkalize at 80 ℃, and liquid-solid mass ratio 10: 1, adds 30% calcium oxide, reaction 10h, and after dealkalize, solid phase is through countercurrent washing, and wash temperature is 90 ℃.In residue, sodium oxide content is 0.98%.
Embodiment 4
By low temperature wet method of the present invention, from flyash, extract the method for aluminum oxide, another the regional flyash of Inner Mongol of take carries out the extraction of aluminum oxide as raw material, and the percentage composition of this flyash principal element oxide compound is as follows:
Al
2o
3siO
2fe
2o
3caO TiO
2na
2o H
2o igloss A/S
48.02 36.38 1.05 2.56 1.40 0.16 5.9 2.57 1.32
The NaOH solution that is 45% with mass percent by flyash mixes and is placed in reactor, alkaline solution and flyash quality proportioning are 8: 1, calcium oxide addition is 40% of flyash quality, be warming up to 300 ℃, under 3.1MPa, react 0.5h, obtain containing the alkali lye of sodium aluminate and the reaction product mixture of dealuminzation slag, reaction product to be mixed is cooled to after 100 ℃, carry out suction filtration, separation obtains alkaline solution and the dealuminzation slag containing sodium aluminate, now in dealuminzation slag A/S=0.08 (A is quality of alumina per-cent, S is siliconoxide mass per-cent), in flyash, the rate of recovery of aluminum oxide is 93.94%.
By what obtain, containing sodium aluminate alkali solution (filtrated stock), put into crystallization reactor, 60 ℃, add 5% crystal seed in the situation that after crystallization 6h, the crystalline mother solution causticity ratio that filtration obtains is elevated to 26, the causticity ratio of aluminate hydrates sodium crystal is 1.36, then to aluminate hydrates sodium crystal dissolve, desiliconization, kind divide, calcine and can make sandy alumina.
Dealuminzation slag adds water and at 180 ℃, carries out dealkalize, and liquid-solid mass ratio 10: 1, does not add calcium oxide, reaction 0.5h, and after dealkalize, solid phase is through countercurrent washing, and wash temperature is 90 ℃.In residue, sodium oxide content is 0.93%.
Embodiment 5
The flyash of embodiment 4 is mixed and is placed in reactor with embodiment 4 crystalline mother solution, mother liquor and flyash quality proportioning are 25: 1, calcium oxide addition is 35% of flyash quality, be warming up to 180 ℃, under 0.4MPa, react 10h, obtain containing the alkali lye of sodium aluminate and the reaction product mixture of dealuminzation slag, reaction product to be mixed is cooled to after 100 ℃, carry out suction filtration, separation obtains alkaline solution and the dealuminzation slag containing sodium aluminate, now in dealuminzation slag A/S=0.07 (A is quality of alumina per-cent, S is siliconoxide mass per-cent), in flyash, the rate of recovery of aluminum oxide is 94.66%.
By what obtain, containing sodium aluminate alkali solution (filtrated stock), put into crystallization reactor, 60 ℃, add 5% crystal seed in the situation that after crystallization 6h, the crystalline mother solution causticity ratio that filtration obtains is elevated to 24, the causticity ratio of aluminate hydrates sodium crystal is 1.30, then to aluminate hydrates sodium crystal dissolve, desiliconization, kind divide, calcine and can make sandy alumina.
Dealuminzation slag adds in the sodium hydroxide solution of 40g/L, carries out dealkalize at 150 ℃, and liquid-solid mass ratio 10: 1, does not add calcium oxide, reaction 6h, and after dealkalize, solid phase is through countercurrent washing, and wash temperature is 90 ℃.In residue, sodium oxide content is 0.89%.
Claims (2)
1. wet method is extracted a method for aluminum oxide from flyash, comprises the following steps:
(1) batching: the NaOH alkaline solution that is 30%-50% by flyash, calcium oxide and mass percent concentration mixes and joins in reactor, alkaline solution and flyash quality proportioning (8-25): 1, the mass ratio of calcium oxide and flyash is (0.35-0.50): 1;
(2) reaction: the material that step (1) is obtained carries out Leaching reaction in reactor, and temperature is 180-300 ℃, extraction time 0.2-10h, leaches pressure 0.4-6.2MPa, after Leaching reaction completes, obtains slip; By this slurry filtration, obtain alkaline solution and dealuminzation slag containing sodium aluminate;
(3) crystallization: the alkaline solution containing sodium aluminate that step (2) is obtained is cooling, adds crystal seed crystallization at 50-100 ℃, obtains aluminate hydrates sodium coarse-grain and crystalline mother solution, and crystalline mother solution is cycled to used in Leaching reaction;
(4) purify and decompose: the aluminate hydrates sodium coarse-grain water that step (3) is obtained or sig water dissolve, and then through desiliconization, seed operation splitting, obtain aluminium hydroxide, then by the aluminium hydroxide calcining obtaining, just making aluminum oxide;
(5) evaporative crystallization: it is 520-600g/L that the seed decomposition nut liquid that step (4) is obtained is evaporated to sodium oxide concentration, then add crystal seed at 50-100 ℃, to carry out crystallization reaction, or join in step (2) gained sodium aluminate solution and carry out together crystallization reaction, crystalline mother solution is for Leaching reaction; Sodium aluminate crystallization mixes with step (4) gained desiliconization sodium aluminate solution after dissolving, and carries out seed decomposition;
(6) de-sodium: the dealuminzation slag that step (2) is obtained joins and take off sodium in dilute alkaline soln and reacts, sig water concentration is 0-80g/L, calcium oxide add-on is the 0-30% of dealuminzation slag amount, liquid-solid mass ratio is (6-10): 1, temperature of reaction 80-180 ℃, reaction times 0.5-10h;
(7) washing: de-sodium slag water carries out repeatedly countercurrent washing, and wash temperature is 50-95 ℃, its washings is for the dissolving of step (3) or step (5) aluminate hydrates sodium coarse-grain, and after washing, de-sodium slag is as the raw material of producing material of construction.
2. method according to claim 1, is characterized in that, the reaction pressure of de-sodium reaction is 0-0.9MPa.
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| CN103663516B (en) * | 2012-09-26 | 2015-08-19 | 中国科学院过程工程研究所 | A kind of method utilizing aluminous fly-ash to prepare aluminium hydroxide |
| CN103803613A (en) * | 2012-11-06 | 2014-05-21 | 贵阳铝镁设计研究院有限公司 | Method using high temperature activation-high pressure water chemical method to treat fly ash to produce alumina |
| CN104140121A (en) * | 2013-05-09 | 2014-11-12 | 中国科学院过程工程研究所 | Method for preparing sodium aluminate solution from coal-series kaolinite or coal gangue used as raw material |
| CN104445310A (en) * | 2013-09-25 | 2015-03-25 | 贵阳铝镁设计研究院有限公司 | Novel process for treating middle-low bauxite in complete wet method alkali system |
| CN103553100B (en) * | 2013-11-19 | 2015-04-01 | 南京天华化学工程有限公司 | Method for extracting aluminum oxide from coal ash through hot-wall reaction |
| CN106145169B (en) * | 2015-04-09 | 2018-02-13 | 中国科学院过程工程研究所 | A kind of method of the wet underwater welding aluminum oxide from aluminous fly-ash |
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| CN108622920A (en) * | 2018-05-30 | 2018-10-09 | 大唐国际发电股份有限公司高铝煤炭资源开发利用研发中心 | A kind of method of aluminous fly-ash extraction aluminium oxide |
| CN108529658B (en) * | 2018-07-05 | 2020-08-07 | 郑州中科新兴产业技术研究院 | Method for recovering aluminum hydroxide from aluminum ash |
| CN109369286B (en) * | 2018-09-18 | 2021-09-21 | 华南理工大学 | Method for producing medium trace element acid soil conditioner by using fly ash and product |
| CN112573552B (en) * | 2020-12-27 | 2022-02-01 | 中南大学 | Method for preparing boehmite by using high-silicon aluminum-containing material |
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| CN1240617C (en) * | 2003-06-24 | 2006-02-08 | 中国科学院过程工程研究所 | Normal pressure low temperature leaching production method for alumina |
| CN101857250A (en) * | 2009-04-09 | 2010-10-13 | 刘庆玲 | Process for producing aluminium hydroxide, silicic acid and sodium carbonate by utilizing fly ash |
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