CN111017969A - Crystallization auxiliary agent for decomposing sodium aluminate seed crystal and preparation method of aluminum hydroxide - Google Patents
Crystallization auxiliary agent for decomposing sodium aluminate seed crystal and preparation method of aluminum hydroxide Download PDFInfo
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- CN111017969A CN111017969A CN201911327219.1A CN201911327219A CN111017969A CN 111017969 A CN111017969 A CN 111017969A CN 201911327219 A CN201911327219 A CN 201911327219A CN 111017969 A CN111017969 A CN 111017969A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/14—Aluminium oxide or hydroxide from alkali metal aluminates
- C01F7/144—Aluminium oxide or hydroxide from alkali metal aluminates from aqueous aluminate solutions by precipitation due to cooling, e.g. as part of the Bayer process
- C01F7/145—Aluminium oxide or hydroxide from alkali metal aluminates from aqueous aluminate solutions by precipitation due to cooling, e.g. as part of the Bayer process characterised by the use of a crystal growth modifying agent other than aluminium hydroxide seed
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Abstract
The invention discloses a crystallization auxiliary agent for decomposing sodium aluminate seed crystals and a preparation method of aluminum hydroxide, which comprises the following components in percentage by weight: and (2) component A: 5-30%, 5-50% of component B and component C: 10-60%, wherein the sum of the weight of the three components is 100%; wherein, the component A is phenolic resin, the component B is polyethylene glycol fatty acid ester, and the component C is biodiesel. The phenolic resin in the crystallization auxiliary agent can be adsorbed on the surface of the aluminum hydroxide crystal, hydrocarbon chain association is easy to occur due to large molecular association energy of the phenolic resin, so that false macromolecules are formed, a bridging effect can be realized among fine aluminum hydroxide particles by using the false macromolecules, the fine aluminum hydroxide particles are promoted to agglomerate and grow, the formation of product fine particles is reduced, and the average particle size of the aluminum hydroxide is increased.
Description
Technical Field
The invention relates to a Bayer process for producing aluminum hydroxide crystals, in particular to a crystallization auxiliary agent for decomposing sodium aluminate crystal seeds and a preparation method of aluminum hydroxide.
Background
Along with the rapid development of electrolytic aluminum, ceramic, medicine, electronics, machinery and other industries in China, the market demand of aluminum oxide is more and more large. The data show that China is the biggest alumina producing country in the world, but the quality and physical properties of alumina still have a large space for improvement. The Bayer Process is one of the major recognized production methods of aluminum hydroxide on an industrial scale, with most Al2O3Is produced from bauxite by the Bayer process. The Bayer process is Karl Bayer 1 by German scientistThe invention in 888 is specifically divided into the following 4 main processes: 1. dissolution-Al in 20% caustic high temperature solution2O3Dissolving out from the ore; 2. settling-separating the solid sludge from the liquid stream; 3. decomposition-crystal seed decomposition of sodium aluminate solution, precipitation of aluminum hydroxide crystals and fractional recovery; 4. roasting-decomposing aluminum hydroxide crystal to remove water and convert into Al2O3. Wherein, the crystal seed decomposition of the sodium aluminate solution is a key process for producing the aluminum hydroxide by the Bayer process, and in the process, Al2O3With Al (OH)3The crystalline form crystallizes out of solution. The supersaturated sodium aluminate solution is cooled from about 100 c to 60 c and the supersaturated solution containing fine particles of aluminum hydroxide seeds is passed through a series of agitated decomposers for decomposition. The solution temperature, the seed size and the seed amount, the solution concentration, the decomposition time and the like are regulated and controlled to control the particle size of the formed aluminum hydroxide crystals and the aluminum hydroxide yield of the solution.
The aluminum hydroxide crystal structure has a strong correlation with the roasting damage rate and the strength of the aluminum oxide particles, each aluminum hydroxide particle can be regarded as a coarse crystal formed by agglomeration of a plurality of aluminum trihydrate single crystals, and the aluminum trihydrate single crystals are in a pseudo hexagonal shape. The structure of the aluminum hydroxide particles is complicated and can be divided into the following types: aluminum hydroxide single crystals, hybrid aluminum hydroxide crystals, and radial aluminum hydroxide crystals. In the bayer process, there are 3 major mechanisms of crystal growth: nucleation; crystal/crystal nucleus growth; aggregation, these mechanisms essentially determine the size and number of crystals.
The decomposition yield is mainly dependent on the production of new fine particles rather than the growth of coarse particles. Thus, (two-hydroxy-Al (OH)3) The quality control is important to the alumina industry. Particles with a radius of 100nm or less are not visible to most detection devices and few mechanisms are known to date regarding nucleation. The currently accepted mechanism is that Al is expressed as Al (OH)3In Bayer solution, and also in polymeric form [ (OH)3Al-O-Al(OH)3]2－And [ Al (OH) ]24]6－Are present.
For hydrogenIn terms of the quality of the alumina, there are two mutually opposing effects in the "agglomeration" process: 1) agglomeration binds the fine particles, coarsening the product particles; 2) the accumulation causes the pockets to become enclosed in the accumulation (when closed), which reduces the purity of the product and increases the alkali content, which in turn affects the cell. Decomposition experiments performed in pure synthetic solution showed that: initially in (By-Al (OH)3) There is a strong repulsive force between the particles and the colloidal crystals and no significant agglomeration occurs. As the pure synthesis solution continued to age, the formation of crystal interfaces and network formation began to be evident, with agglomeration between coarse particles being visible due to particle gluing and intergrowth. Due to (two-alkyl-Al (OH)3) The movement of crystal growth is slow and therefore, the production of commercially valuable coarse crystals is largely dependent on the aggregation mechanism.
Subsequent processing to produce aluminum metal and the like, generally requires obtaining aluminum hydroxide product of larger crystal size, however, generally results in smaller particles of aluminum hydroxide being produced due to limitations imposed by the processing conditions under which crystallization and decomposition occur (e.g., temperature profile, seed charge, seed surface area, carbon dioxide or flue gas cleanup, liquid loading and liquid purity, etc.). It is currently the main content of the craftsman how to produce the maximum possible yield from aluminate process liquors while achieving a given crystal size distribution of the aluminium hydroxide product. However, since the processing conditions vary from plant to plant, finding chemical additives and methods to improve the seed decomposition process of sodium aluminate solution is one of the best ways to improve the particle size of the product and increase the decomposition rate. This process provides a reduced percentage of small size crystals and increases the yield of coarser aluminum hydroxide crystals by adding surfactant dissolved in oil to the solution during the precipitation stage. The research on the strengthening decomposition of the sodium aluminate solution is one of the hot directions of the seed precipitation process research of the sodium aluminate solution. The method for strengthening the decomposition of the sodium aluminate solution by adopting the Crystalline Growth Modifier (CGM) has the advantages of simple operation, low cost and the like, and the Crystalline Growth Modifier (CGM) can reduce ultrafine particles and increase the particle strength, so that the method is a strengthening method which is deeply researched and has an industrial application prospect. The crystallization auxiliary agent can reduce the generation of the superfine aluminum hydroxide particles to the maximum extent, ensure that more uniform seed crystal particles with consistent sizes are produced, and reduce the sensitivity of the Bayer process decomposition process to Bayer cycle process parameters.
At present, the electrolytic bath in the electrolytic aluminum industry in China has obvious heavy current trend, the demand on sandy alumina is strong day by day, and the crystallization auxiliary agent is the most effective means for helping alumina factories to produce sandy alumina at present. However, the crystallization aid produced in China at present is low in quality and mainly depends on import, so that the crystallization aid with the quality comparable to that of European and American chemical industry can have great market potential if the crystallization aid can be developed.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. To this end, the present invention provides a crystallization aid for the decomposition of sodium aluminate seeds, which is capable of reducing the formation of product fines while increasing the average particle size of aluminum hydroxide.
The invention also provides a method for producing aluminum hydroxide by using the sodium aluminate.
The crystallization aid according to an embodiment of the first aspect of the present invention is composed of the following components in percentage by weight: and (2) component A: 5-30%, 5-50% of component B and component C: 10-60%, wherein the sum of the weight of the three components is 100%; wherein, the component A is phenolic resin, the component B is polyethylene glycol fatty acid ester, and the component C is biodiesel.
According to some embodiments of the invention, the content of component a is 10% to 20%; more preferably 15%.
According to some embodiments of the invention, the content of component B is 20% to 40%; more preferably 25% to 35%.
According to some embodiments of the invention, the content of component C is 20% to 50%; more preferably 35% to 45%.
According to some embodiments of the invention, the component a is a cresol-formaldehyde resin; preferably, the component A is
n is the degree of polymerization; preferably, then is 2-10; more preferably 5 to 7.
According to some embodiments of the invention, the polyethylene glycol fatty acid ester is a polyalkylene glycol ester of a fatty acid; preferably, the raw material for preparing the polyethylene glycol fatty acid ester contains 1 to 20 moles of ethylene oxide per mole of polyethylene glycol fatty acid ester; preferably, the fatty acid is oleic acid, tall oil or stearic acid; more preferably, the monomer of the polyethylene glycol fatty acid ester is a monoester or a diester; more preferably, the polymerization degree of the polyethylene glycol fatty acid ester is 200 to 800.
The crystallization aid provided by the embodiment of the invention has at least the following beneficial effects: the phenolic resin in the crystallization aid can be adsorbed on the surface of an aluminum hydroxide crystal, hydrocarbon chain association is easy to occur due to large molecular association energy of the phenolic resin, so that false macromolecules are formed, a bridging effect can be realized among fine aluminum hydroxide particles by using the false macromolecules, the agglomeration and the growth of the fine aluminum hydroxide particles are promoted, the formation of product fine particles is reduced, and the average particle size of the aluminum hydroxide is increased; according to the crystallization auxiliary agent, biodiesel and polyethylene glycol fatty acid ester have a dispersing and emulsifying effect on the component A, and further have a synergistic effect on the component A; compared with the prior art, the crystallization aid is more effective, has more excellent performance and is low in cost.
A method for producing aluminum hydroxide according to an embodiment of the second aspect of the present invention includes the steps of: adding the crystallization aid into the sodium aluminate solution to prepare the aluminum hydroxide through a Bayer process, wherein the crystallization aid is used for helping to control the nucleation of the aluminum hydroxide, and the final concentration of the crystallization aid in the sodium aluminate solution is not more than 50 ppm.
According to some embodiments of the invention, the crystallization aid has a final concentration in the sodium aluminate solution of (5-30) ppm; preferably (7 to 20) ppm; more preferably 8 ppm. According to some embodiments of the present invention, the crystallization aid is added after fine filtration of the sodium aluminate solution before decomposition. Or may be added in a seed decomposing tank or a decomposing tank.
The preparation method provided by the embodiment of the invention has at least the following beneficial effects: according to the technical scheme, the crystallization auxiliary agent is used in the crystal seed decomposition process, so that the problem that the nucleation of the aluminum hydroxide is controlled in the crystal seed decomposition process of the sodium aluminate solution is effectively solved, the formation of fine particles of the product is reduced, and the average particle size of the aluminum hydroxide is increased.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Detailed Description
In order to explain the technical content, the objects and the effects of the present invention in detail, the following description will be given with reference to the embodiments.
The first embodiment of the invention is as follows: a crystallization aid for decomposing sodium aluminate seed crystals consists of the following components: a:
n is 4; b; polyethylene glycol distearate (400); c: biodiesel; wherein the mass ratio of the component A is 15 percent; the weight ratio of the component B is 25 percent; the weight ratio of the component C is 60 percent.
The second embodiment of the invention is as follows: a crystallization aid for decomposing sodium aluminate seed crystals consists of the following components: a:
n is 6; b; polyethylene glycol distearate (400); c: biodiesel; wherein, the mass ratio of the component A is 20 percent; the weight proportion of the component B is 30 percent; the weight ratio of the component C is 50 percent.
The third embodiment of the invention is as follows: a crystallization aid for decomposing sodium aluminate seed crystals consists of the following components: a:
n is 8; b; polyethylene glycol distearate (400); c: biodiesel; wherein, the mass ratio of the component A is 30 percent; the weight ratio of the component B is 15 percent; the weight ratio of the component C is 55 percent.
The crystallization aid in the above examples 1 to 3 was used for the effect test, and the test process was as follows:
taking a sodium aluminate solution of a certain factory and an aluminum hydroxide seed crystal of the factory for testing, wherein the sodium aluminate solution comprises the following components: total alkalinity (NK) 160g/l, and the mass ratio of alumina to caustic (Rp) 1.05.
A 6-head 125ml steel bomb test kettle with a temperature controller is used for carrying out a decomposition experiment, the decomposition temperature is 65 ℃, the decomposition time is 16h, and the decomposition solid content is 400 g/L; specifically, heating the test kettle to 65 ℃, keeping the temperature constant, respectively adding about 100ml of semen into 6 beakers, heating to 70 ℃, adding a crystallization aid, uniformly stirring, adding seed crystals, uniformly stirring, and simultaneously, rapidly transferring to a steel bomb; starting a reaction kettle rotating device, and decomposing for 16 hours at constant temperature; after 16h, the decomposed slurry was discharged and filtered through slow filter paper to analyze the particle size of the aluminum hydroxide in the filter cake.
As a control, a control test was carried out under the same conditions (30 ppm in all the amounts) using a commercially available crystallization aid.
The above operations were tested in parallel twice, and the particle size of the aluminum hydroxide in the filter cakes obtained in the above examples and comparative examples was counted, and the results are shown in the following table 1:
TABLE 1
As can be seen from the above table, the addition of the crystallization aid in the examples to the sodium aluminate solution reduced the formation of fines in the product relative to the existing commercial maturation agents, with the sample in example 2 being the most reduced.
The particle size statistics of the aluminum hydroxide in the filter cake obtained after 16h of isothermal decomposition, which were tested with different dosages of commercially available products and crystallization aid in example 2, are shown in table 2 below:
TABLE 2 influence of different dosages on the particle size of aluminium hydroxide results table
As can be seen from Table 2, the addition of various amounts of the crystallization aid of the examples of the present invention reduced the production of fine-grained aluminum hydroxide to various degrees, with the greatest reduction being around 30ppm, relative to the commercial product.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent modifications made by the present invention in the specification or directly or indirectly applied to the related technical field are included in the scope of the present invention.
Claims (10)
1. A crystallization auxiliary agent for decomposing sodium aluminate seed crystals is characterized in that: the composition comprises the following components in percentage by weight: and (2) component A: 5-30%, 5-50% of component B and component C: 10-60%, wherein the sum of the weight of the three components is 100%; wherein, the component A is phenolic resin, the component B is polyethylene glycol fatty acid ester, and the component C is biodiesel.
2. The crystallization aid for sodium aluminate seed decomposition according to claim 1, characterized in that: the content of the component A is 10 to 20 percent; preferably 15%.
3. The crystallization aid for sodium aluminate seed decomposition according to claim 1, characterized in that: the content of the component B is 20 to 40 percent; preferably 25% to 35%.
4. The crystallization aid for sodium aluminate seed decomposition according to any one of claims 1 to 3, characterized in that: the content of the component C is 20-50%; preferably 35 to 45%.
5. The crystallization aid for sodium aluminate seed decomposition according to claim 1, characterized in that: the component A is cresol-formaldehyde resin.
6. The crystallization aid for sodium aluminate seed decomposition according to claim 1, characterized in that: the component A is
n is the degree of polymerization; preferably, n is 2-10; more preferably 5 to 7.
7. The crystallization aid for sodium aluminate seed decomposition according to claim 1, characterized in that: the polyethylene glycol fatty acid ester is polyalkylene glycol ester of fatty acid; preferably, the fatty acid is oleic acid, tall oil or stearic acid; more preferably, the monomer of the polyethylene glycol fatty acid ester is a monoester or a diester; more preferably, the polymerization degree of the polyethylene glycol fatty acid ester is 200 to 800.
8. A preparation method of aluminum hydroxide is characterized by comprising the following steps: the method comprises the following steps: aluminum hydroxide is prepared by the bayer process by adding a crystallization aid according to any one of claims 1 to 7 to a sodium aluminate liquor, said crystallization aid serving to help control aluminum hydroxide nucleation, said crystallization aid having a final concentration in the sodium aluminate liquor of not more than 50 ppm.
9. The method for producing aluminum hydroxide according to claim 8, characterized in that: the final concentration of the crystallization auxiliary agent in the sodium aluminate solution is (5-30) ppm; preferably (7 to 20) ppm; more preferably 8 ppm.
10. The method for producing aluminum hydroxide according to claim 8, characterized in that: the crystallization aid is added after the fine filtration of the sodium aluminate solution and before the decomposition.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111717938A (en) * | 2020-06-22 | 2020-09-29 | 华友新能源科技（衢州）有限公司 | Narrowly distributed small-particle-size nickel-cobalt-aluminum hydroxide and preparation method thereof |
| CN111717939A (en) * | 2020-06-22 | 2020-09-29 | 华友新能源科技（衢州）有限公司 | Narrowly distributed large-particle-size nickel-cobalt-aluminum hydroxide and preparation method thereof |
| CN112194157A (en) * | 2020-10-29 | 2021-01-08 | 武汉工程大学 | Alumina crystallization auxiliary agent and preparation method thereof |
| CN112194158A (en) * | 2020-10-29 | 2021-01-08 | 武汉工程大学 | Crystallization auxiliary agent used in alumina production process and preparation method thereof |
| CN115281187A (en) * | 2022-08-11 | 2022-11-04 | 北京广源益农化学有限责任公司 | Stable pesticide synergist and preparation method thereof |
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| CN105050956A (en) * | 2013-03-14 | 2015-11-11 | 艺康美国股份有限公司 | Crystallization aids for bayer aluminum hydroxide |
Non-Patent Citations (1)
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| 毕见强: "《特种陶瓷工艺与性能》", 31 December 2018 * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111717938A (en) * | 2020-06-22 | 2020-09-29 | 华友新能源科技（衢州）有限公司 | Narrowly distributed small-particle-size nickel-cobalt-aluminum hydroxide and preparation method thereof |
| CN111717939A (en) * | 2020-06-22 | 2020-09-29 | 华友新能源科技（衢州）有限公司 | Narrowly distributed large-particle-size nickel-cobalt-aluminum hydroxide and preparation method thereof |
| CN111717938B (en) * | 2020-06-22 | 2022-10-14 | 华友新能源科技（衢州）有限公司 | Narrowly distributed small-particle-size nickel-cobalt-aluminum hydroxide and preparation method thereof |
| CN111717939B (en) * | 2020-06-22 | 2022-10-14 | 华友新能源科技（衢州）有限公司 | Narrowly distributed large-particle-size nickel-cobalt-aluminum hydroxide and preparation method thereof |
| CN112194157A (en) * | 2020-10-29 | 2021-01-08 | 武汉工程大学 | Alumina crystallization auxiliary agent and preparation method thereof |
| CN112194158A (en) * | 2020-10-29 | 2021-01-08 | 武汉工程大学 | Crystallization auxiliary agent used in alumina production process and preparation method thereof |
| CN115281187A (en) * | 2022-08-11 | 2022-11-04 | 北京广源益农化学有限责任公司 | Stable pesticide synergist and preparation method thereof |
| CN115281187B (en) * | 2022-08-11 | 2023-11-24 | 北京广源益农化学有限责任公司 | Stable pesticide synergist and preparation method thereof |
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