KR100996472B1 - Method for manufacturing high purity aluminium trihydroxide - Google Patents

Abstract

PURPOSE: A producing method of high-purity aluminum hydroxide is provided to optimize a weight ratio, the amount of an adsorbent, stirring speed, adhesion time, and the precipitation temperature time of a base liquid for securing high quality. CONSTITUTION: A producing method of high-purity aluminum hydroxide comprises the following steps: forming a base liquid by dissolving aluminum hydroxide in a liquid with a weight ratio of 0.68~0.72(S110); aging impurities inside the base liquid(S120); adsorbing the impurities with an adsorbent formed with a pulp material(S200); separating the pulp material, and firstly filtering the base liquid before transferring the liquid to a precipitation tank(S310); applying an aluminum hydroxide seed to the liquid and segregating the aluminum hydroxide(S320); dividing the outcome by particle size(S330); secondly filtering the base liquid including the segregated material with a big particle size(S340); and washing and drying the result(S350).

Description

Method for manufacturing high purity aluminum trihydroxide

The present invention relates to a method for producing high purity aluminum hydroxide, and more specifically, before the Bayer process, general aluminum hydroxide is dissolved in a caustic soda (NaOH) solution to ripen the dissolved liquid, and then a small amount of adsorbent is used. By selectively removing only the impurities in the aged solution to produce a high purity aluminum hydroxide, the coprecipitation step of co-precipitating the impurities present in the dissolved solution with aluminum hydroxide before using a conventional Bayer revolver, aluminum hydroxide A method of manufacturing high purity aluminum hydroxide that can solve the difficulties of commercialization due to excessive loss of products, waste generation, and inefficiency while reducing costs and producing high quality high purity aluminum hydroxide in an eco-friendly way. It is about.

High purity aluminum hydroxide is recently used in special ceramics, high purity glass for producing IC, optical glass, high purity aluminum compound and high purity alumina raw material. Recently, it is also a compound that is in the spotlight in connection with LED products such as LED TV.

In order to manufacture such high-purity aluminum hydroxide, a Bayer process is essential in the process of preparing a compound, which is a caustic soda (NaOH) to extract aluminum hydroxide present in the bauxite ore. A method of depositing aluminum hydroxide dissolved in the caustic soda after dissolving aluminum hydroxide by dissolving aluminum hydroxide by heating the bauxite in a solution (dissolution step).

The aluminum hydroxide produced by the Bayer process contains a large amount of impurities by the impurities introduced from the bauxite introduced in the melting process and the residues of the subsidiary materials used in the Bayer process.

Therefore, the general Bayer process alone could not produce high purity aluminum hydroxide above a certain purity. Accordingly, some methods of removing metal ions using an organic solvent such as Isodecanol and Kerosene after dissolving aluminum hydroxide in acid to remove impurities have been mobilized. However, such an impurity removal method is difficult to operate, and expensive solvent extractants have to be used as well as problems such as environmental pollution.

In addition, the manufacturing method using aluminum (Al) metal is also used, but also because of the high manufacturing cost, it is not clear whether to commercialize. In practice, high-purity aluminum hydroxide manufacturing method is a private know-how, commercialized only by one or two companies worldwide. It is a situation.

The present invention has been made to solve the above technical problem, and after dissolving the general aluminum hydroxide using a caustic soda (NaOH) solution, the dissolved liquid is aged (in the term used herein, "maturation" This refers to growing particles in a dissolved state) to activate impurities and to adsorb impurities present in the dissolved liquid using an adsorbent made of pulp material, and then to purify the dissolved liquid effectively by filtering. It is an object of the present invention to provide a high purity aluminum hydroxide production method capable of mass-producing high purity aluminum hydroxide in a low cost and environmentally friendly manner by depositing a high purity aluminum hydroxide using a Bayer process.

In addition, the present invention has developed the optimum conditions such as the weight ratio of the process mother liquor, the maturation time, the amount of the adsorbent, the stirring speed, the adsorption time, the precipitation temperature and the precipitation time, which is an important condition required for the production of high purity aluminum hydroxide, having a purity of 99.9 or more. It is an object of the present invention to provide a method for producing high purity aluminum hydroxide.

Preferred embodiment of the high-purity aluminum hydroxide manufacturing method according to the present invention, the mother liquor preparation step of dissolving and aging the general aluminum hydroxide, and after the mother liquor preparation step, a purifying step of adsorbing impurities from the mother liquor prepared by the addition of pulp, After the refining step, after the seed is added to the mother liquor to precipitate, and obtaining a high-purity aluminum hydroxide for filtering, washing and drying the precipitated material.

Here, the mother liquor preparation step, the general aluminum hydroxide and caustic soda (NaOH) in the dissolution tank to dissolve the general aluminum hydroxide to form a mother liquor, and the temperature of the mother liquor dissolved through the dissolution step a predetermined aging time It may include a aging process to mature the impurities while slowly lowering.

Another embodiment of the high-purity aluminum hydroxide manufacturing method according to the present invention, by adding a sodium hydroxide solution (NaOH) and a general aluminum hydroxide in a dissolution tank to dissolve the general aluminum hydroxide to form a mother liquor, and after a predetermined time after the dissolution step Aging process of slowly lowering the temperature of the mother liquor to mature the impurities, purifying the adsorbent of pulp material to the mother liquor aged through the aging process to disperse the impurities in the mother liquor to the adsorbent, and after the purification process is completed The first filtration step of separating the pulp adsorbed with impurities, filtering the mother liquor and sending it to the precipitation tank, and the precipitation step of depositing aluminum hydroxide by administering aluminum hydroxide seed to the mother liquor of the precipitation tank after the first filtration step. And, after the precipitation step to separate the precipitate having a small particle size and the precipitate having a large particle size A second filtration step of filtering the mother liquor containing precipitates having large particles in the polarization step and the polarization step, and recycling the filtrate to the caustic soda solution; and washing the precipitates filtered through the second filtration step to remove water. It includes a drying step.

)가 0.68∼0.72이다.Here, the dissolution step is a weight ratio of aluminum oxide to sodium hydroxide of the dissolved mother liquid (

) Is 0.68 to 0.72.

)을 기준으로 270g/l 이상이다.In addition, the concentration of caustic soda (NaOH) in the dissolution step is sodium carbonate (

) Is greater than or equal to 270 g / l.

In addition, the maturing temperature of the mother liquid in the aging step can be maintained at 130 ℃ to 90 ℃ or more for a predetermined time.

In addition, the aging time for aging the impurities in the aging process may be 1 hour or more.

In addition, the precipitation process may be performed at an initial temperature of 85 ℃ or more.

In addition, in the precipitation process, the precipitation time for depositing aluminum hydroxide may be performed for 72 hours or more.

)는 0.36 이하일 수 있다.
In addition, the weight ratio of aluminum oxide to sodium hydroxide finally obtained in the precipitation step (

) May be less than or equal to 0.36.

The method for producing high purity aluminum hydroxide according to the present invention has an effect of producing environmentally friendly high purity aluminum hydroxide by adsorbing impurities using an adsorbent such as pulp.

In addition, the high-purity aluminum hydroxide manufacturing method according to the present invention not only suggests important precipitation conditions accompanying various processes in addition to the refining process, but also eliminates difficult and expensive processes such as coprecipitation process, and thus high purity aluminum hydroxide. It can be produced at low cost.

1 is a block diagram showing a sequential manufacturing process of a high-purity aluminum hydroxide manufacturing method according to the present invention.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of a high-purity aluminum hydroxide manufacturing method according to the present invention will be described in detail.

1 is a block diagram showing a sequential manufacturing process of a high-purity aluminum hydroxide manufacturing method according to the present invention.

) 과포화 용액을 만든다.In general, in order to manufacture aluminum hydroxide, bauxite is dissolved in a high concentration of caustic soda (NaOH) solution in a heated and pressurized state, and sodium aluminate,

) Make a supersaturated solution.

After the sodium aluminate thus made is left to pass through a filtration step to remove undissolved impurities (S210), the purified sodium aluminate solution is slowly cooled down for a long time to start precipitation at a high temperature. As a method of descending, the precipitation process is performed to finally produce the desired aluminum hydroxide. Here, in order to manufacture high purity aluminum hydroxide with high purity, a purification process (S210) for removing impurities in the process is very important, and recent research in the related industry also focuses on the purification process (S210), which is a process for increasing purity. It is a fact.

One preferred embodiment of the high purity aluminum hydroxide manufacturing method according to the present invention, as shown in Figure 1, provides a variety of experimental processes for increasing the purity of the finally obtained aluminum hydroxide.

In more detail, in the method for producing high purity aluminum hydroxide according to the present invention, after the aging of the sodium aluminate supersaturated solution, the sodium aluminate solution is purified using an adsorbent adsorbing impurities, and impurities are adsorbed. In addition to removing a small amount of pulp, the purified sodium aluminate solution is slowly lowered the temperature over a long time to start precipitation at a high temperature to complete the precipitation at a low temperature to produce a high purity aluminum hydroxide.

More generally, when describing a high-purity aluminum hydroxide manufacturing method according to the present invention, as shown in Figure 1, the present invention, the mother liquor preparation step (S100) and the mother liquor preparation step (S100) for aging after dissolving the general aluminum hydroxide ( S100), after purifying the adsorbed impurities from the mother liquor prepared by adding the pulp (S200), and after the purification step (S200), after the seed is added to the mother liquor to precipitate, the precipitated material is filtered, washed and dried An acquisition step (S300) of acquiring high purity aluminum hydroxide is included.

In particular, the purification step (S200) is unique in that it adsorbs impurities using an adsorbent such as pulp instead of the coprecipitation method of coprecipitation of impurities in the mother liquor with conventional aluminum hydroxide seeds.

Here, the mother liquor preparation step (S100), by dissolving the general aluminum hydroxide and sodium hydroxide (NaOH) in the dissolution tank to dissolve the general aluminum hydroxide to make a mother liquor, and dissolution through the dissolution step (S110) Aging process (S120) for aging the impurities while slowly lowering the temperature of the prepared mother liquor for a predetermined aging time.

In the method of manufacturing high purity aluminum hydroxide according to the present invention, in addition to the refining step (S200), important conditions are suggested in the manufacturing process, and thus the scope of the present invention is not limited by the embodiments as described above. Be careful.

For example, another embodiment of the high-purity aluminum hydroxide manufacturing method according to the present invention, under more precise conditions, can be obtained in a more detailed process than the above-described embodiment to obtain the final aluminum hydroxide.

That is, another embodiment of the high-purity aluminum hydroxide manufacturing method according to the present invention, as shown in Figure 1, in order to prepare a sodium aluminate supersaturated solution, the caustic soda solution (NaOH) and a general aluminum hydroxide in a dissolution tank general Melting step (S110) of dissolving aluminum hydroxide to form a mother liquor, aging step (S120) of slowly lowering the temperature of the mother liquor over a predetermined time after the dissolving step (S110) to mature impurities, and the aging step (S120) By separating and dispersing the adsorbent of the pulp material in the mother liquor through the refining step (S210) for adsorbing the impurities in the mother liquor to the adsorbent, and separating the pulp to adsorb the impurities after the refining step (S210) is completed, After filtering the mother liquor, the first filtration step (S310) sent to the precipitation tank, and after the first filtration step (S310) by administering aluminum hydroxide seed to the mother liquor of the precipitation tank The precipitation step of precipitation of aluminum oxide, and the precipitates which are less grown after the precipitation process, i.e., the precipitates which are completely grown, that is, the precipitates which are grown completely, that is, the particles having large particle size are separated, are used as the aluminum hydroxide seeds of the precipitation process. A second filtration step (S340) and a second filtration step of filtering the mother liquor containing the precipitate having a large particle in the polarization step (S330) and the polarization step (S330) and recycling the filtrate to the caustic soda solution. It includes a drying step (S340) for removing the water after washing the precipitate filtered through (S340).

Referring to the high-purity aluminum hydroxide manufacturing method according to the present invention configured as described above in more detail.

)을 기준으로 210∼280g/l 로 만들어 넣고, 수분이 함유된 일반수산화알루미늄을

의 중량비(A/C : weight ratio)가 0.60∼0.72가 되도록 일반수산화알루미늄을 첨가한 후, 수산화알루미늄을 분산시키기 위하여 교반속도를 30RPM으로 교반하면서 온도를 120∼130℃로 상승시킨 후, 10분 정도 유지(용해공정(S110)시킨 결과, 표 1 및 표 2에서 알 수 있는 바와 같이

의 중량비(A/C)가 0.68 내지 0.72이고, 가성소다(NaOH) 용액을 탄산나트륨(

)를 기준으로 270g/l 및 280g/l, 즉 270g/l이상으로 한 경우 불순물이 최소화 되었다.First, a solution of caustic soda (NaOH) was added to a sodium carbonate solution to prepare a sodium aluminate process mother liquor in a melting tank made of stainless steel (Sus 316L) that can raise the temperature.

) Of 210-280 g / l based on the standard, and the water containing ordinary aluminum hydroxide

Aluminum hydroxide was added so as to have a weight ratio of 0.60 to 0.72, and then the temperature was raised to 120 to 130 DEG C with stirring at a stirring speed of 30 RPM to disperse the aluminum hydroxide, (The dissolution step (S110), as shown in Tables 1 and 2,

(A / C) of 0.68 to 0.72, and the caustic soda (NaOH) solution is added to a solution of sodium carbonate

) Was 270 g / l and 280 g / l, that is, 270 g / l or more, the impurities were minimized.

의 중량비(A/C)를 아래의 표 1에 기재된 중량비인 0.68과 0.70의 중간수치인 0.69인 상태에서 상기 수산화알루미늄을 완전히 용해시킨 공정모액을 만들기 위하여, 상기 가성소다 농도는

를 기준으로 270g/l 이 되도록 하여 용해조에 넣고 온도를 125℃까지 승온시킨 후 그 상태에서 10분간 유지하였다.Applicant, among the above rough conditions,

(A / C) was completely dissolved in the state of 0.69, which is an intermediate value between 0.68 and 0.70, shown in Table 1 below, and the caustic soda concentration was

To 270g / l based on the temperature was put in the dissolution tank and the temperature was raised to 125 ℃ and maintained for 10 minutes in that state.

In this way, in the state where the aluminum hydroxide is completely dissolved so that the A / C of the process mother liquor is 0.69, the stirrer is slowly operated at a speed of about 3 RPM to stir the process mother liquor, and the mother liquor temperature is maintained for 1 hour or more. Aged slowly by lowering to 100 ℃. Here, the reason for aging the process mother liquor is to increase the particle size of the impurities so as to easily remove the impurities contained in the process mother liquor as described above. (Maturation process (S120))

A / C
Ingredient 0.60 0.62 0.64 0.66 0.68 0.70 0.72 Remarks Fe (ppm) 15 11 8 6 5 5 5 Ca (ppm) 10 7 5 4 4 4 4

Effect of product on weight ratio of process mother liquor

g/l
제품성분

g / l
Ingredient 210 220 230 240 250 260 270 280 Fe (ppm) 15 13 12 10 8 5 4 4 Ca (ppm) 7 7 6 5 4 4 4 4 Na (%) 0.11 0.08 0.06 0.04 0.03 0.02 0.02 0.02

Effect of Products on Caustic Soda Concentration

Meanwhile, as shown in Table 3, the applicant found that the A / C of the mother liquor of the process was 0.69, the concentration of the caustic soda was 270 g (based on sodium carbonate) / l, we found that the most suitable aging time should last more than one hour. In particular, there is an advantage in manufacturing a high-purity aluminum hydroxide that can be used in LED products that are recently attracting attention only if the content of Fe is less than 5ppm, the maturing time of the process mother liquor should be maintained for at least 1 hour. desirable.

Aging time (minutes)
ingredient 30 60 120 180 240 300 Fe (ppm) 15 4 4 4 4 4 Ca (ppm) 6 4 4 4 4 4

Impurity Contents of High Purity Products According to Aging Time of Process Mother Solution

Next, as shown in Table 4 and Table 5 in the process mother liquor well aged to remove impurities contained in the process mother liquor, which corresponds to 1 g per liter, which is the condition that the highest production rate of impurities and the highest impurities removal rate are shown. The pulp was added, and the stirrer speed was raised to 5 RPM as shown in Table 6 to disperse the pulp in the mother liquor for 10 minutes to adsorb impurities (purification step (S210)).

Pulp consumption g / l after filtration
Process mother liquor component 0 0.2 0.4 0.6 0.8 1.0 1.5 2 3

0.69 0.69 0.69 0.69 0.69 0.69 0.69 0.69 0.69 Fe (ppm) 11 8 5 4 3 2 2 2 2 Ca (ppm) 5 One One One One One One One One

Effect of process mother liquor on the amount of adsorbent pulp to remove impurities in process mother liquor (preparation mother liquor temperature 100 ℃, stirring speed 5RPM. Stirring time 10 minutes)

Stirring speed
ingredient 0 rpm 2 rpm 4 rpm 6 rpm 8 rpm 10 rpm 12 rpm A / C of mother liquor 0.69 0.69 0.69 0.69 0.69 0.69 0.69 Fe (ppm) content of process mother liquor after pulp administration 11 6 2 2 2 2 2

Change of process mother liquor according to stirrer speed (RPM) during 10 min reaction time

Response time (minutes)
ingredient 0 5 10 15 20 25 Mother liquor A / C after filtration 0.69 0.69 0.69 0.69 0.69 0.69 Fe (ppm) 11 2 2 2 2 2 Ca (ppm) 5 One One One One One

Change of process mother liquor according to adsorption time (temperature 95 ℃, pulp consumption 1g / l, stirring speed 5RPM)

당 가로 및 세로 25cm×25cm 여과 면적의 폴리에틸렌(Poly ethylene) 재질의 여포를 부착한 필터 여과기(Filter press)를 이용하여 2기압 압력으로 여과하여 불순물이 제거된 깨끗한 공정모액은 그 다음 공정인 석출공정을 위해 석출조로 보내고, 불순물을 흡착시킨 상기 펄프는 세척 후 재활용 폐기물로 처리한다.(제1여과공정(S310))On the other hand, the pulp adsorbed impurities from the process mother liquor is removed in the next step of the first filtration process (S310), where the mother liquor 1 to remove the pulp

The clean process mother liquor was removed by filtration at 2 atmospheres using a filter press with a polyfoam of 25 cm x 25 cm filtration area. The pulp is sent to the precipitation tank for adsorption, and the pulp adsorbed with impurities is treated as recycled waste after washing (first filtration step S310).

의 중량비가 0.69이고, 온도는 90℃로 유지된 상태다. 상기 석출공정은 석출물과 종자가 부상될 수 있도록 교반기의 속도를 15RPM으로 증가시키고, 석출을 돕기 위해 수산화알루미늄 종자(평균입도 30um)를 모액 1L당 40g을 넣어 표 7에 나타나 있는 바와 같이 90℃ 이상에서 석출을 시작하고, 표 8에 나타난 바와 같이 그 석출시간은 72시간 이상으로 유지시킨다.(석출공정)
As such, the purified process mother liquor from which impurities are removed is subjected to a precipitation process next. At this time, the process mother liquor

The weight ratio of is 0.69, and the temperature is maintained at 90 ° C. The precipitation process is to increase the speed of the stirrer to 15RPM so that the precipitates and seeds can be floated, and 40g per 1L of the mother hydroxide seed (average particle size 30um) to aid precipitation, as shown in Table 7 above 90 ℃ Precipitation is started at, and the precipitation time is maintained at 72 hours or more as shown in Table 8.

Initial precipitate
Temperature
ingredient 90 ° C 85 ℃ 80 ℃ 75 ℃ 70 ℃ 65 ℃ Na wt% in the precipitate 0.02 0.02 0.04 0.08 0.15 0.30

Na% content of precipitate according to initial precipitation temperature (precipitation time 72 hours)

Hour (hr)
ingredient 48 60 72 84 96 108 120 132 Final process weight ratio 0.38 0.36 0.34 0.34 0.33 0.33 0.33 0.32 Na% in precipitate 0.21 0.10 0.02 0.02 0.02 0.02 0.02 0.02

중량비(최종 석출온도 40℃, 초기 석출온도 90℃, 종자 65g/l, 평균입도 40um)
Na content of precipitate according to precipitation time and final process solution after precipitation

Weight ratio (final precipitation temperature 40 ℃, initial precipitation temperature 90 ℃, seed 65g / l, average particle size 40um)

의 중량비(A/C)가 0.34 이하로 됨을 알 수 있었다. 이처럼, 최종 석출액의 중량비(A/C)가 0.34 이하일 경우에는 품질과 경쟁성을 갖추는 조건이 된다.The precipitate precipitated through the precipitation process becomes high purity aluminum hydroxide having a smaller impurity content ratio as the content of the caustic soda (NaOH) is minimized. As the precipitation conditions such that the content of the caustic soda can be minimized, Applicants, as shown in Tables 7 and 8, the initial precipitation temperature 90 ℃, the final precipitation temperature 40 ℃, the precipitation time was 72 hours or more Case, the final precipitate

It was found that the weight ratio (A / C) of became 0.34 or less. As such, when the weight ratio (A / C) of the final precipitate is 0.34 or less, it is a condition of having quality and competitiveness.

Next, when the precipitation process is completed, the polarization process (S330) is started. In the polarization step (S330), precipitates having less growth are separated as precipitates having an average particle size of 30 μm or less using a cyclone polarizer, and are used as aluminum hydroxide seeds administered during the precipitation process, and particles having a well-grown precipitate (average) Particle size 60um) is subjected to the second filtration process (S340) to be continued. (Polarization process (S330))

After the polarization step (S330), the well-grown precipitate having an average particle size of 60um is separated into a solid and a filtrate by using a filter, and the filtrate is recycled to the use of caustic soda solution required for the dissolution step (S110) and recycled, and high purity hydroxide. The precipitate, which is aluminum, is a fluidizing blower type dryer that can minimize contamination after washing with clean water of 80 ° C. or higher and dried within 130 minutes at 130 ° C. to remove moisture without causing a phase transition. Filtration process (S340) and drying process (S340))

The high purity aluminum hydroxide obtained by drying in this way is finally packaged through the packaging process (S360) is completed (packaging process (S360)).

Kinds
ingredient High Purity Aluminum Hydroxide Prepared By The Invention Conventional High Purity Aluminum Hydroxide Conventional Generalized Aluminum

％

% > 99.9 > 99.9 > 99.7 Na% 0.02 0.04 0.15 Fe ppm <3 <5 100 Si ppm <2 <5 65 Ti ppm <3 <3 40 Mg ppm <1 <1 30 Ca ppm <1 <1 7

Comparison between high purity aluminum hydroxide prepared by the production method according to the present invention and conventional aluminum hydroxide

Or more, with reference to the accompanying drawings, a preferred embodiment and another embodiment of a high-purity aluminum hydroxide manufacturing method according to the present invention has been described in detail. However, embodiments of the present invention are not necessarily limited thereto, and it is obvious that various modifications or other embodiments falling within the scope equivalent to the present invention may be implemented by those skilled in the art. Therefore, the true scope of the present invention will be defined by the claims below.

S100: mother liquor preparation step S110: dissolution process
S120: aging process S200: purification step
S210: Refining Process S300: Acquisition Step
S310: first filtration process S320: precipitation process
S330: polarization step S340: second filtration step
S350: drying process S360: packaging process

Claims (7)

The weight ratio of aluminum oxide to sodium hydroxide in the mother liquor in which caustic soda solution (NaOH) and aluminum hydroxide were added to a dissolution tank was dissolved.

) Is in the range of 0.68 to 0.72, thereby producing a mother liquor;
A aging step of slowly lowering the temperature of the mother liquor over a predetermined time after the dissolution step to mature impurities;
A purifying step of adding and dispersing an adsorbent made of pulp material to the mother liquor aged through the aging step to adsorb impurities in the mother liquor to the adsorbent;
A first filtration step of separating the pulp to which the impurities are adsorbed after the purification step is completed, and filtering the mother liquor and then sending it to a precipitation tank;
A precipitation step of depositing aluminum hydroxide by administering aluminum hydroxide seed to the mother liquor of the precipitation tank after the first filtration step;
A polarization step of separating the precipitate having a small particle size and the precipitate having a large particle size after the precipitation process;
A second filtration step of filtering the mother liquor containing the large precipitate in the polarization step and recycling the filtrate to the caustic soda solution;
It includes a drying step of removing water after washing the precipitate filtered through the second filtration process,
The concentration of caustic soda (NaOH) in the dissolution step is sodium carbonate (

) Of not less than 270 g / l.
delete The method according to claim 1,
Method of producing a high purity aluminum hydroxide to maintain the aging temperature of the mother liquor in the aging step at 130 ℃ to 90 ℃ over a predetermined time.
The method according to claim 3,
The aging time for the maturation of impurities in the aging step is 1 hour or more.
The method according to claim 1,
The precipitation process is a high purity aluminum hydroxide manufacturing method is carried out at an initial temperature of 85 ℃ or more.
The method according to claim 1,
The precipitation step is a high-purity aluminum hydroxide manufacturing method in which the precipitation time for depositing aluminum hydroxide is performed for 72 hours or more.
The method according to claim 1,
The weight ratio of aluminum oxide to sodium hydroxide finally obtained in the precipitation step (

) Is a method of producing high purity aluminum hydroxide less than 0.36.

Images