CN118373436A - Preparation method and system of oxalate remover for aluminum oxide - Google Patents

Preparation method and system of oxalate remover for aluminum oxide Download PDF

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CN118373436A
CN118373436A CN202410327697.7A CN202410327697A CN118373436A CN 118373436 A CN118373436 A CN 118373436A CN 202410327697 A CN202410327697 A CN 202410327697A CN 118373436 A CN118373436 A CN 118373436A
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oxalate
remover
alumina
preparing
slurry
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罗春
成林娟
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Shandong Hannodi New Materials Co ltd
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Shandong Hannodi New Materials Co ltd
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Abstract

The invention provides a preparation method and a system of an oxalate remover for alumina, and belongs to the technical field of removers. According to the method, firstly, benzenesulfonic acid solution and yttrium hydroxide slurry are subjected to an aging reaction to obtain solid yttrium benzenesulfonate, then tetrabutylammonium chloride ethanol and sodium hydroxide are subjected to a heat preservation reaction, the mixture is concentrated to obtain crystalline tetrabutylammonium hydroxide, and tetrabutylammonium hydroxide crystals and yttrium benzenesulfonate solids are mixed to obtain the oxalate remover for aluminum oxide. The oxalate remover prepared by the invention can effectively remove oxalate, and can be used for keeping the concentration of oxalate existing in a system within a controllable range, thereby limiting harmful effects and balancing the input of oxalate in bauxite.

Description

Preparation method and system of oxalate remover for aluminum oxide
Technical Field
The invention relates to the technical field of removers, in particular to a preparation method and a system of an oxalate remover for alumina.
Background
The organic matters in the alumina production flow are mainly from bauxite and process organic additives such as flocculating agents, defoamers, crystallization aids, dehydrating agents and the like. In general, about 95% of the organic matters in bauxite are the main sources. Bauxite in different regions have different organic matter contents, and the Total Organic Carbon (TOC) in the ore is generally between 0.04 and 0.4 percent. Oxalate is produced during digestion by conversion of bauxite and organic compounds in the circulating mother liquor. Of the oxalate produced in the bauxite degradation product of the circulating mother liquor, 20% came from the organics in the circulating mother liquor and 80% came from the organics in the bauxite.
Oxalate is continuously gathered in the Bayer cycle process, and can be periodically and explosive separated out to form 'oxalate rain'. Because the fine needle-like oxalate forms a "cheese-like" foam with the sodium aluminate solution and the air therein. The foam of the decomposing tank can reach several meters or even more than ten meters, so that a decomposing area forms a foam waterfall, and serious potential safety hazards and environmental accidents are caused. The tank top discharging system (such as middle temperature reduction, grader and seed filtration) is completely paralyzed. The seed filtration productivity is severely reduced, the productivity may be reduced by 60-70%, and finally the dissolution yield is reduced or the production is stopped. The foam in the decomposing mother solution tank flows transversely in full, so that environmental accidents are caused.
The presence of crystalline sodium oxalate during the decomposition of aluminum hydroxide increases the rate of formation of fines, resulting in product refinement. The presence of crystalline oxalate on the seed can interfere with agglomeration. The presence of crystalline sodium oxalate adversely affects seed fractionation. The presence of crystalline sodium oxalate causes an increase in product sodium. In summary, the presence of oxalate crystals can result in reduced product quality.
The periodic precipitation of oxalate rain, which is similar to the sudden drop in the production flow of alumina by the Bayer process, can cause scab on the seed crystal tank, the decomposition tank, the vertical disc filter, the evaporator and the like.
Therefore, when the oxalate amount brought in when the bauxite with high organic matters is used for producing alumina exceeds the self-balancing capacity of an alumina factory, the problems of production reduction, quality reduction, safety, environmental protection and the like of the alumina are caused. To solve the problems associated with oxalate, excess oxalate must be removed.
Disclosure of Invention
In view of the above, the present invention is directed to a method for producing an oxalate remover for alumina. The oxalate remover prepared by the method has high removal rate which is up to more than 52%, and good filtering performance, and solves the problem that the conventional method has extremely poor filtering performance and cannot normally run.
The method for preparing the oxalate remover for alumina comprises the following steps:
(1) Mixing benzenesulfonic acid with deionized water, and dissolving to form benzenesulfonic acid solution with the mass concentration of 50-55%; mixing and grinding yttrium hydroxide with deionized water for 3-5 hours to prepare yttrium hydroxide slurry with the mass concentration of 10-20%;
(2) Slowly adding yttrium hydroxide slurry into benzenesulfonic acid solution according to the molar ratio of 1.05-0.95:0.95-1.05, stirring at 75-80 ℃ at constant temperature, and aging for 10-20 hours;
(3) Carrying out flash evaporation concentration on the solution obtained after the ageing reaction in the step (2) to obtain solid yttrium benzenesulfonate, drying the yttrium benzenesulfonate at 140-180 ℃, and recycling condensed water as deionized water;
(4) Adding ethanol into a reaction kettle, adding tetrabutylammonium chloride under stirring, then adding solid powder sodium hydroxide, and reacting for 10-20 hours at 25-50 ℃; wherein the weight ratio of the ethanol to the tetrabutylammonium chloride is 2.5-4.0: 1.0, the molar ratio of tetrabutylammonium chloride to sodium hydroxide is 1.0:0.9-1.1;
(5) Centrifugally filtering the slurry after the reaction in the step (4) to obtain filtrate;
(6) Distilling the filtrate obtained in the step (5) at 80 ℃, crystallizing the obtained concentrated solution to obtain tetrabutylammonium hydroxide crystals, condensing ethanol and recycling the condensed ethanol;
(7) Mixing the solid in the step (3) and the crystal in the step (6) according to the weight ratio of 0.1-0.9:0.9-0.1 to obtain the oxalate remover for alumina.
Preferably, the temperature of the deionized water in the step (1) is 80-85 ℃.
Preferably, the yttrium hydroxide particles in the slurry of step (1) have a size D90 of 3 to 5 microns.
Preferably, the ethanol concentration in step (4) is greater than 97%.
It is another object of the present invention to provide a system for preparing an oxalate remover for alumina, comprising, in order, a dissolution tank, a grinder, a slurry tank, a reaction vessel I, a flash evaporator, a gas stream dryer, a reaction vessel II, a centrifuge, a filtrate tank, a distiller, a crystallizer, and a mixer.
Preferably, the dissolving tank is provided with a stirring device. The dissolving tank is made of strong acid and alkali resistant stainless steel, and the stirring paddle can be inclined paddle type, anchor type, frame type, propelling type, single screw type or double screw type.
Preferably, the grinding machine is a sand mill or a stirring mill, and the lining material is alumina or zirconia.
Preferably, the slurry tank is provided with stirring paddles;
preferably, a stirring device is arranged in the reaction kettle I. The reaction kettle I is electrically heated and steam heated, is jacketed, is made of strong acid and alkali resistant stainless steel, and can be inclined paddle type, anchor type, frame type, propelling type, single screw type or double screw type.
Preferably, a stirring device is arranged in the reaction kettle II. The reaction kettle II is electrically heated and steam heated, is jacketed and is made of strong acid and alkali resistant stainless steel, and the stirring paddles can be inclined paddles, anchor paddles, frame paddles, propelling paddles, single screw paddles or double screw paddles.
The system is used for preparing the oxalate remover for alumina, and the specific reaction process is as follows:
firstly adding benzenesulfonic acid and deionized water into a dissolving tank to form benzenesulfonic acid solution; simultaneously adding yttrium hydroxide and deionized water into a sand mill for grinding, and placing the obtained yttrium hydroxide slurry into a slurry tank;
Then adding benzenesulfonic acid solution into a reaction kettle I, and slowly adding yttrium hydroxide slurry into the reaction kettle I for aging reaction; carrying out flash evaporation concentration on the reacted solution in a flash evaporation evaporator, and drying the obtained solid in an airflow dryer;
Adding ethanol into a reaction kettle II, starting stirring, and then sequentially adding tetrabutyl ammonium chloride and solid powder sodium hydroxide for reaction; centrifugally filtering the reacted slurry in a centrifugal separator, and enabling the obtained filtrate to enter a filtrate tank; distilling the filtrate in distiller to obtain concentrated solution, and crystallizing in crystallizer;
and finally, feeding the solid in the airflow dryer and the crystal in the crystallizer into a mixer for mixing to obtain the oxalate remover for alumina.
Compared with the prior art, the invention has the following beneficial effects: the invention provides a method for preparing an oxalate remover for aluminum oxide, which comprises the steps of respectively preparing solid yttrium benzenesulfonate and crystalline tetrabutylammonium hydroxide, and then mixing to obtain the oxalate remover. The oxalate remover prepared by the invention can effectively remove oxalate, and can be used for keeping the concentration of oxalate existing in a system within a controllable range, thereby limiting harmful effects and balancing the input of oxalate in bauxite.
Adding an oxalate remover into the supersaturated sodium aluminate solution, and staying in a reaction tank for a certain time to promote the precipitation of oxalate, inhibit the needle growth of oxalate, promote the growth, the coarseness and the agglomeration of oxalate and ensure that the oxalate slurry can be subjected to very easy solid-liquid separation.
The oxalate remover prepared by the method has high removal rate which is up to more than 52%, and good filtering performance, and solves the problem that the conventional method has extremely poor filtering performance and cannot normally run.
Drawings
FIG. 1 is a schematic diagram of a system for preparing an oxalate remover for alumina according to the present invention;
FIG. 2 is an SEM of the crystal structure of oxalate in experiment 3;
FIG. 3 is a SEM of hollow white oxalate crystal growth of experiment 1;
FIG. 4 is an SEM of oxalate crystal growth in experiment 3;
Fig. 5 is a system state diagram between oxalate and sodium hydroxide NT in a sodium aluminate solution.
In FIG. 1, 1-dissolution tank, 2-grinder, 3-slurry tank, 4-reaction vessel I, 5-flash evaporator, 6-air dryer, 7-reaction vessel II, 8-centrifuge, 9-filtration tank, 10-distiller, 11-crystallizer, 12-mixer.
Detailed Description
The invention is further illustrated below with reference to examples.
Example 1
A method for preparing an oxalate remover for alumina, comprising the following steps:
(1) Mixing benzenesulfonic acid with deionized water at 80 ℃ and dissolving to form benzenesulfonic acid solution with the mass concentration of 50%; mixing and grinding yttrium hydroxide with deionized water at 80 ℃ for 3 hours to prepare yttrium hydroxide slurry with the mass concentration of 10%, wherein the granularity D90 of the yttrium hydroxide in the slurry is 3-5 microns;
(2) Slowly adding yttrium hydroxide slurry into benzenesulfonic acid solution according to the molar ratio of 1.0:1.05, stirring at constant temperature of 80 ℃, and aging for 20 hours;
(3) Carrying out flash evaporation concentration on the solution obtained after the ageing reaction in the step (2) to obtain solid yttrium benzenesulfonate, drying the yttrium benzenesulfonate at 150 ℃, and recycling condensed water as deionized water;
(4) Adding 99% ethanol into a reaction kettle, adding tetrabutylammonium chloride under stirring, and then adding solid powder sodium hydroxide, wherein the weight ratio of the ethanol to the tetrabutylammonium chloride is 2.5:1.0, the molar ratio of tetrabutylammonium chloride to sodium hydroxide is 1.0:1.0, and the reaction is carried out for 20 hours at the temperature of 40 ℃;
(5) Centrifugally filtering the slurry after the reaction in the step (4) to obtain filtrate;
(6) Distilling the filtrate obtained in the step (5) at 80 ℃, crystallizing the obtained concentrated solution to obtain tetrabutylammonium hydroxide, condensing ethanol and recycling;
(7) Mixing the solid in the step (3) and the crystal in the step (6) according to the mass ratio of 0.8:0.2 to obtain the oxalate remover for alumina.
Embodiments of the present invention are particularly carried out in a system for preparing an oxalate remover for alumina, comprising, in order, a dissolution tank (1), a grinder (2), a slurry tank (3), a reaction vessel I (4), a flash evaporator (5), a gas stream dryer (6), a reaction vessel II (7), a centrifuge (8), a filtrate tank (9), a distiller (10), a crystallizer (11), and a mixer (12).
In the system, the specific reaction process is as follows:
Firstly, adding benzenesulfonic acid and deionized water into a dissolving tank (1), and starting stirring to form benzenesulfonic acid solution; simultaneously adding yttrium hydroxide and deionized water into a sand mill (2) for grinding, and placing the obtained yttrium hydroxide slurry into a slurry tank (3) for stirring;
Then adding benzenesulfonic acid solution into a reaction kettle I (4), slowly adding yttrium hydroxide slurry into the reaction kettle I, heating and stirring at constant temperature, and carrying out aging reaction; carrying out flash evaporation concentration on the reacted solution in a flash evaporation evaporator (5), and drying the obtained solid in an airflow dryer (6);
Adding ethanol into a reaction kettle II (7), starting stirring, and then sequentially adding tetrabutylammonium chloride and solid powder sodium hydroxide for heat preservation reaction; centrifugally filtering the reacted slurry in a centrifugal separator (8), and enabling the obtained filtrate to enter a filtrate tank (9); delivering the filtrate into a distiller (10) for distillation, and delivering the obtained concentrated solution into a crystallizer (11) for crystallization;
finally, the solid in the air dryer and the crystal in the crystallizer are sent into a mixer (12) to be mixed together, and the oxalate remover for alumina is obtained.
A schematic of the system is shown in fig. 1.
The process of the invention can also be carried out in conventional laboratory apparatus.
The oxalate removal test was performed using the oxalate remover for alumina prepared in example 1, and the specific method was as follows:
(1) Preparing a sodium aluminate solution: a certain amount of decomposing mother liquor of a certain factory is taken and added into a beaker, and the mixture is heated, boiled, evaporated and concentrated on an electric furnace, and the concentrated sodium aluminate solution obtained after concentration has the components shown in Table 1:
TABLE 1
Composition of the components Na2OT Na2Ok Al2O3 Rp C2O4 2-
Concentration/g. L -1 196.6 185.7 88.8 0.478 3.74
Na 2OT and Na 2Ok represent all sodium hydroxide and caustic sodium hydroxide, respectively
(2) Taking 900ml of the sodium aluminate solution, dividing into 6 equal parts, respectively filling the equal parts into 6 plastic bottles of 250ml, respectively adding the sodium oxalate remover according to 0, 5, 10 and 10g/L (experiments 1-6), screwing a cover, uniformly stirring, putting into a 60 ℃ constant-temperature water bath oscillator for preserving heat and vibrating, carrying out suction filtration on all slurries after 4 hours, recording the suction filtration time, simultaneously taking filtrate to measure the concentration of filtrate C 2O4 2-, and taking filter cakes for SEM analysis (as shown in figure 2).
The oxalate removal rate calculation method is shown as the formula (1)
ηa=(1-Cn/C0)×100 (1)
Wherein, C 0 -initial C 2O4 2- concentration of solution; c n -concentration of sample solution C 2O4 2- after incubation.
The initial C 2O4 2- concentration of the sodium aluminate solution was measured to be 3.74g, L -1, and the residual C 2O4 2- concentration of the blank and the sample solution added with the oxalate remover were measured by shaking at a constant temperature for 4 hours, respectively, and the removal rate was calculated, and the results are shown in Table 2.
TABLE 2
Fig. 2-4 are SEM images of different oxalate crystals. Wherein FIG. 2 shows the SEM of the crystal structure of oxalate in experiment 3 (5 g/L of the oxalate remover of example 1 was added), FIG. 3 shows the SEM of the growth of the crystal of white oxalate in experiment 1 (no oxalate remover was added), and FIG. 4 shows the SEM of the growth of the crystal of oxalate in experiment 3 (5 g/L of the oxalate remover of example 1 was added). As can be seen from SEM, the oxalate crystals grow in needle form along {001} planes without the remover, and the crystals are thin and long needle-like crystals, whereas the oxalate crystals propagate along {200} planes to form coarse crystals after the remover is added. Thus, it is possible to obtain: adsorption of oxalate remover molecules on the surface of Na 2C2O4 crystals and their subsequent incorporation into the crystal matrix of Na 2C2O4 crystals. The {001} plane preferentially adsorbed on the top of the needle shape is then incorporated into the crystal matrix, induces internal stress (defect) of the crystal, and promotes propagation of the base {200} twin plane to form a coarse crystal.
Preparing 50-300 g/L sodium hydroxide NT concentration test solution from a certain alumina factory industrial sodium aluminate solution through evaporation or dilution, heating the test solution to 100 ℃, adding excessive sodium oxalate to dissolve for 24 hours, and filtering to analyze the concentration of oxalate in a liquid phase; and cooling the test solution to 60 ℃, adding a certain amount of activated carbon adsorbent to remove humic acid substances (the main cause of supersaturation of sodium oxalate) in the test solution, stirring for 10 minutes, filtering to remove the activated carbon adsorbent, and preserving the temperature of the filtered solution at 60 ℃ for 48 hours to obtain the concentration of oxalate in the filtered solution, so as to obtain a system state diagram between the oxalate and sodium hydroxide NT in the sodium aluminate solution, as shown in figure 5.
From fig. 5, it can be derived that: the oxalate exists in the sodium aluminate solution in a solubility curve and a supersaturation curve, and the state of the oxalate in the sodium aluminate solution is divided into three regions. The area A is an oxalate stabilizing area, so that oxalate is very stable in sodium aluminate solution and cannot be separated out; the area B is an oxalate metastable area, and the area between the solubility curve and the critical concentration curve can not be automatically separated out if no external inducement exists; the area C is an unstable area, and the area above the critical concentration curve can automatically separate out the oxalate, and the oxalate must be removed to reduce the concentration of the oxalate, so that the concentration of the oxalate is controlled in the area B or the area A. When the oxalate remover is added into a sodium aluminate solution, a plurality of very fine yttrium hydroxide colloid particles are generated in the process, the particles have a structure like a plurality of gaps of zeolite, the surface activity is very high, and organic matters such as humic acid and the like (such matters cause oxalate supersaturation) can be adsorbed, so that sodium oxalate crystallization is induced.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (10)

1. A method of preparing an oxalate remover for alumina, comprising the steps of:
(1) Mixing benzenesulfonic acid with deionized water, and dissolving to form benzenesulfonic acid solution with the mass concentration of 50-55%; mixing and grinding yttrium hydroxide with deionized water for 3-5 hours to prepare yttrium hydroxide slurry with the mass concentration of 10-20%;
(2) Slowly adding yttrium hydroxide slurry into benzenesulfonic acid solution according to the molar ratio of 1.05-0.95:0.95-1.05, stirring at 75-80 ℃ at constant temperature, and aging for 10-20 hours;
(3) Carrying out flash evaporation concentration on the solution obtained after the ageing reaction in the step (2) to obtain solid yttrium benzenesulfonate, drying the yttrium benzenesulfonate at 140-180 ℃, and recycling condensed water as deionized water;
(4) Adding ethanol into a reaction kettle, adding tetrabutylammonium chloride under stirring, then adding solid powder sodium hydroxide, and reacting for 10-20 hours at 25-50 ℃; wherein the weight ratio of the ethanol to the tetrabutylammonium chloride is 2.5-4.0: 1.0, the molar ratio of tetrabutylammonium chloride to sodium hydroxide is 1.0:0.9-1.1;
(5) Centrifugally filtering the slurry after the reaction in the step (4) to obtain filtrate;
(6) Distilling the filtrate obtained in the step (5) at 80 ℃, crystallizing the obtained concentrated solution to obtain tetrabutylammonium hydroxide crystals, condensing ethanol and recycling the condensed ethanol;
(7) Mixing the solid in the step (3) and the crystal in the step (6) according to the weight ratio of 0.1-0.9:0.9-0.1 to obtain the oxalate remover for alumina.
2. The method for preparing an oxalate remover for alumina according to claim 1, wherein the temperature of deionized water in the step (1) is 80-85 ℃.
3. The method of preparing an oxalate remover for alumina according to claim 1, wherein the yttrium hydroxide in the slurry in step (1) has a particle size D90 of 3-5 microns.
4. The method for producing an oxalate remover for alumina according to claim 1, wherein the concentration of ethanol in step (4) is more than 97%.
5. A system for preparing oxalate remover for alumina is characterized by sequentially comprising a dissolving tank, a grinding machine, a slurry tank, a reaction kettle I, a flash evaporation evaporator, an airflow dryer, a reaction kettle II, a centrifugal separator, a filtrate tank, a distiller, a crystallizer and a mixer.
6. The system for preparing an oxalate remover for alumina according to claim 5, wherein the dissolution tank is provided with a stirring device.
7. The system for preparing an oxalate remover for alumina according to claim 5, wherein the grinder is a sand mill or a stirring mill, and the lining material is alumina or zirconia.
8. The system for preparing an oxalate remover for alumina according to claim 5, wherein the slurry tank has a stirring slurry therein.
9. The system for preparing an oxalate remover for alumina according to claim 5, wherein the reaction kettle I is provided with a stirring device.
10. The system for preparing an oxalate remover for alumina according to claim 5, wherein the reaction kettle II is provided with a stirring device.
CN202410327697.7A 2024-03-21 2024-03-21 Preparation method and system of oxalate remover for aluminum oxide Pending CN118373436A (en)

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