阅读说明：本技术 一种α相超细低钠氧化铝粉体的制备方法 (Preparation method of alpha-phase superfine low-sodium alumina powder ) 是由 熊林 徐强 吴海文 杨辉 张正林 李冬云 覃剑 于铁妮 于 2019-09-23 设计创作，主要内容包括：本发明公开一种α相超细低钠氧化铝粉体的制备方法,包括以下步骤：A、将工业氢氧化铝与去离子水混合后,用砂磨机研磨30-120min,获得固相质量分数为35-50%的悬浮液；B、在悬浮液中添加除钠剂,在超声作用下反应,再用去离子水清洗,获得氢氧化铝细粉；C、将氢氧化铝细粉在1150-1350℃下煅烧1-6h,获得α相超细低钠氧化铝粉体。本发明具有工艺过程简单,步骤紧凑,投资少,成本低,可以较快制备α相超细低钠氢氧化铝粉体,具有推广意义。(The invention discloses a preparation method of alpha-phase superfine low-sodium alumina powder, which comprises the following steps: A. mixing industrial aluminum hydroxide and deionized water, and grinding for 30-120min by using a sand mill to obtain a suspension liquid with the solid phase mass fraction of 35-50%; B. adding a sodium removing agent into the suspension, reacting under the action of ultrasound, and then cleaning with deionized water to obtain aluminum hydroxide fine powder; C. calcining the aluminum hydroxide fine powder at 1150-gradient 1350 ℃ for 1-6h to obtain alpha-phase ultrafine low-sodium alumina powder. The method has the advantages of simple process, compact steps, less investment and low cost, can quickly prepare the alpha-phase superfine low-sodium aluminum hydroxide powder, and has popularization significance.)

1. The preparation method of the alpha-phase superfine low-sodium alumina powder is characterized by comprising the following steps of:

A. mixing industrial aluminum hydroxide and deionized water, and grinding for 30-120min by using a sand mill to obtain a suspension liquid with the solid phase mass fraction of 35-50%;

B. adding a sodium removing agent into the suspension, reacting under the action of ultrasound, and then cleaning with deionized water to obtain aluminum hydroxide fine powder;

C. calcining the aluminum hydroxide fine powder at 1150-gradient 1350 ℃ for 1-6h to obtain alpha-phase ultrafine low-sodium alumina powder.

2. The method for preparing alpha-phase ultrafine low-sodium alumina powder according to claim 1, wherein the method comprises the following steps: the adding amount of the deionized water in the step A is equal to 100-185% of the weight of the industrial aluminum hydroxide.

3. The method for preparing alpha-phase ultrafine low-sodium alumina powder according to claim 1, wherein the method comprises the following steps: and the sodium removing agent in the step B is at least one of hydrochloric acid, acetic acid, citric acid and the like.

4. The method for preparing alpha-phase ultrafine low-sodium alumina powder according to claim 1, wherein the method comprises the following steps: and in the step B, the addition amount of the sodium removing agent is 0.2-3% of the weight of the suspension.

5. The method for preparing alpha-phase ultrafine low-sodium alumina powder according to claim 1, wherein the method comprises the following steps: the pH value of the solution after cleaning in the step B is 6-7, and Na in the aluminum hydroxide fine powder₂The content of O is less than or equal to 0.1 percent.

6. The method for preparing alpha-phase superfine low-sodium alumina powder according to claim 1, wherein the frequency of ultrasonic action in the step B is 20-120kHz, the temperature is 40 ℃ and ~ 70 ℃ and the time is 20-120 min.

7. The method for preparing alpha-phase ultrafine low-sodium alumina powder according to claim 1, wherein the method comprises the following steps: the aluminum hydroxide fine powder in the step B is powder with the particle size less than or equal to 5 mu m.

Technical Field

The invention belongs to the technical field of chemistry, and particularly relates to a preparation method of alpha-phase superfine low-sodium alumina powder.

Background

The high-quality superfine alumina has a series of excellent characteristics of high whiteness, fine granularity, uniform particle size distribution, perfect crystal form, high strength, corrosion resistance, high temperature resistance and the like, can be used for preparing products such as refractory materials, transparent ceramics, lithium battery diaphragm materials, high-performance ceramics, artificial gems, precision polishing materials, semiconductor materials and the like, and is one of new materials which are rapidly developed in the world at present. However, the high-quality alumina produced in China has a larger gap compared with the foreign well-known companies (such as Japanese Sumitomo, Japanese Mingming chemical and French Baikowski, etc.), and the purity, granularity and dispersity of the product in China can not meet the market demand. Therefore, the preparation technology of high-quality ultrafine alumina powder with proprietary intellectual property rights is very urgent.

At present, the conventional alumina powder crushing process in China usually adopts a ball milling process, but the problems of coarse particle size, long crushing time and the like still exist. In the sodium removing process, simple mechanical stirring is mostly adopted, so that the sodium removing times are more, the time is longer, and the sodium removing effect is limited. The CN104229844B patent does not add external force and only uses sodium removing agent to wash simply, the sodium removing effect is limited, and the number of times of sodium removing is more. In the patent CN108675327A, aluminum hydroxide is calcined into aluminum oxide and then sodium removal is carried out, the hydration activity of the aluminum hydroxide is not utilized, and the comprehensive sodium removal effect is reduced. In the patent CN102320638A, the aluminum hydroxide powder is directly subjected to hydrothermal sodium removal, and internal sodium ions are released without ball milling crushing, so that the sodium removal effect is limited.

From the view of the subsequent preparation process of alumina calcination, the smaller the aluminum hydroxide powder particles are, the lower the alumina calcination temperature can be moderately reduced. Therefore, the aluminum hydroxide is considered to be an effective method for preparing high-quality superfine alumina through grinding, external force sodium removal and low-temperature calcination.

Disclosure of Invention

The invention provides a preparation method of alpha-phase superfine low-sodium alumina powder aiming at the problems.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the preparation method of the alpha-phase superfine low-sodium alumina powder comprises the following steps:

A. mixing industrial aluminum hydroxide and deionized water, and grinding for 30-120min by using a sand mill to obtain a suspension liquid with the solid phase mass fraction of 35-50%;

B. adding a sodium removing agent into the suspension, reacting under the action of ultrasound, and then cleaning with deionized water to obtain aluminum hydroxide fine powder;

C. calcining the aluminum hydroxide fine powder at 1150-gradient 1350 ℃ for 1-6h to obtain the superfine low-sodium alumina powder.

Further, the amount of the deionized water added in the step A is equal to 100-185% of the weight of the industrial aluminum hydroxide.

Further, the sodium removing agent in the step B is at least one of hydrochloric acid, acetic acid, citric acid and the like.

Furthermore, the addition amount of the sodium removing agent in the step B is 0.2-3% of the weight of the suspension.

Further, the pH value of the solution after cleaning in the step B is 6-7, and Na in the aluminum hydroxide fine powder₂The content of O is less than or equal to 0.1 percent.

Further, the frequency of the ultrasonic action in the step B is 20-120kHz, the temperature is 40-70 ℃, and the time is 20-120 min.

Further, the fine aluminum hydroxide powder in the step B is powder with the particle size less than or equal to 5 mu m.

The invention has the beneficial effects that:

for 50 μm powder, mechanical stirring can reduce part of the impurity content, but for ultra-fine particles, the traditional mechanical stirring has limited sodium removal effect. The invention forms acting force on the particle surface by means of the action of ultrasonic external force, so that impurities such as sodium salt and the like attached to the surface are stripped, meanwhile, the solid-liquid contact surface is improved, and the dissolution of the sodium removing agent to soluble substances is accelerated. Proper ultrasonic frequency, temperature and time are selected, so that the sodium removal effect of the alumina superfine impurities can be improved, and the purity of the alumina powder is improved.

The invention uses the sand mill to replace the ball mill in the prior art, can reduce the particle size of the powder from 50 mu m to about 2 mu m in a short time,thereby releasing a large amount of sodium ions in the industrial aluminum hydroxide, combining ultrasonic treatment to provide external force action, adding the acid sodium removing agent to remove sodium, and quickly and efficiently reducing the sodium content (namely Na) of the aluminum hydroxide₂O content is less than or equal to 0.1 percent), the sodium removing times are reduced, finer aluminum hydroxide particles are obtained, and then the finer aluminum hydroxide particles are used for calcination, so that the calcination temperature can be properly reduced, the calcination time can be shortened, and the alpha phase transformation rate can be improved.

The method has the advantages of simple process, no need of complex equipment, convenient operation, no need of pressurized hydrothermal reaction, short time consumption, low energy consumption, less investment and low cost, can prepare the alpha-phase superfine low-sodium aluminum hydroxide powder which fully meets the actual requirement, has lower cost of the prepared product, and has popularization significance.

Detailed Description

The present invention will be described in detail below with reference to specific examples.