阅读说明：本技术 一种高密度碳酸钙粉体的制备方法 (preparation method of high-density calcium carbonate powder ) 是由 颜培刚 于 2019-10-07 设计创作，主要内容包括：本发明公开了一种高密度碳酸钙粉体的制备方法,步骤如下：将氧化钙和热水混合搅拌制备成氢氧化钙浆料,调整好浆料的浓度和温度,并去除杂质；在碳化罐中加入氢氧化钙浆料,启动搅拌器,通入二氧化碳气体,使氢氧化钙和二氧化碳发生合成反应；进行分步留浆碳化,直至生浆全部合成碳酸钙粒子后,切断二氧化碳气体导入；停止搅拌,移出碳酸钙浆料；将碳酸钙浆料用离心机进行脱水,形成滤饼；将滤饼烘干；将干燥好的滤饼用解聚机打成粉体,包装,制成高密度碳酸钙粉体。本发明通过用氧化钙和二氧化碳为原料,采用分步留浆碳化合成的工艺,制备振实密度可达到1.1～1.3克/毫升的高密度碳酸钙粉体,保证产品密度,降低制备成本。(The invention discloses a preparation method of high-density calcium carbonate powder, which comprises the following steps: mixing and stirring calcium oxide and hot water to prepare calcium hydroxide slurry, adjusting the concentration and temperature of the slurry, and removing impurities; adding calcium hydroxide slurry into a carbonization tank, starting a stirrer, and introducing carbon dioxide gas to enable calcium hydroxide and carbon dioxide to generate a synthetic reaction; carrying out step-by-step slurry retention and carbonization until the raw slurry is completely synthesized into calcium carbonate particles, and cutting off the introduction of carbon dioxide gas; stopping stirring, and removing the calcium carbonate slurry; dehydrating the calcium carbonate slurry by using a centrifugal machine to form a filter cake; drying the filter cake; and (4) beating the dried filter cake into powder by using a depolymerizer, and packaging to prepare the high-density calcium carbonate powder. According to the invention, calcium oxide and carbon dioxide are used as raw materials, and a step-by-step slurry-remaining carbonization synthesis process is adopted to prepare the high-density calcium carbonate powder with the tap density of 1.1-1.3 g/ml, so that the product density is ensured, and the preparation cost is reduced.)

1. a preparation method of high-density calcium carbonate powder is characterized by comprising the following steps: the method comprises the following steps:

1) mixing and stirring calcium oxide and hot water to prepare calcium hydroxide slurry, adjusting the concentration and temperature of the slurry, and removing impurities;

2) adding calcium hydroxide slurry with adjusted concentration and temperature into a carbonization tank, wherein the liquid level of the slurry is 20-50% of the height of the carbonization tank, starting a stirrer, introducing carbon dioxide gas to enable the calcium hydroxide and the carbon dioxide to generate a synthetic reaction, and gradually reducing the pH value of the slurry;

3) When the reaction is finished and the pH value of the slurry reaches 7, adding the calcium hydroxide slurry into the carbonization tank again until the pH value of the slurry reaches more than 13, stopping adding the calcium hydroxide slurry, uniformly stirring, and continuing the carbonization reaction to return the pH value of the calcium carbonate slurry to 7;

4) Continuously repeating the operation of the step 3) until the material level in the carbonization tank reaches 100 percent;

5) Starting a slurry outlet pump to move the slurry with the pH value of 7 out of the carbonization tank until the slurry liquid level in the carbonization tank is 20-70%, and continuing the operation of the step 3);

6) continuously repeating the step 5) under the condition that the calcium hydroxide slurry is enough until the pH value is 7 after the raw slurry is completely synthesized into the calcium carbonate particles, and cutting off the introduction of carbon dioxide gas; stopping stirring, and removing the calcium carbonate slurry;

7) Dehydrating the calcium carbonate slurry by using a centrifugal machine to form a filter cake with 20-22% of water; the density of the filter cake is 2.3-2.5 g/ml;

8) drying the filter cake until the water content is below 0.5%;

9) And beating the dried filter cake into powder by using a depolymerizer, and packaging to prepare the high-density calcium carbonate powder with the tap density of 1.1-1.3 g/ml.

2. The method for preparing high-density calcium carbonate powder according to claim 1, wherein the method comprises the following steps: the temperature of the hot water in the step 1) is 50-70 ℃, the concentration range of the calcium hydroxide slurry is 10-20 Baume degrees, and the temperature is 20-70 ℃.

3. The method for preparing high-density calcium carbonate powder according to claim 1, wherein the method comprises the following steps: the density of the filter cake prepared in the step 7) is 2.4 g/ml, and the density of the high-density calcium carbonate powder prepared in the step 9) is 1.2 g/ml.

4. the method for preparing high-density calcium carbonate powder according to claim 1, wherein the method comprises the following steps: the density of the filter cake prepared in the step 7) is 2.3 g/ml, and the density of the high-density calcium carbonate powder prepared in the step 9) is 1.1 g/ml.

5. The method for preparing high-density calcium carbonate powder according to claim 1, wherein the method comprises the following steps: the density of the filter cake prepared in the step 7) is 2.5 g/ml, and the density of the high-density calcium carbonate powder prepared in the step 9) is 1.3 g/ml.

Technical Field

the invention belongs to the field of high-density powder preparation, and particularly relates to a preparation method of high-density calcium carbonate powder.

Background

the theoretical density of calcium carbonate powder is 2.93, the tap density of calcium carbonate existing in a powder state is far lower than the theoretical density due to the existence of a stacking space, wherein the density of heavy calcium powder obtained by grinding calcite is 1.15-1.3 g/ml, but the cost is high, while calcium carbonate particles can form a lot of cavities due to the rapid generation and stacking growth of crystals in the carbonization synthesis process of common light calcium carbonate, so that the tap density of the calcium carbonate particles is far lower than the theoretical density of the calcium carbonate, generally only 0.6-0.7 g/ml, but for some special industries, the tap density of the calcium carbonate needs to be improved to the maximum extent.

disclosure of Invention

in order to solve the defects and shortcomings in the prior art, the invention provides the preparation method of the high-density calcium carbonate powder, which is used for preparing the high-density calcium carbonate powder with the tap density of 1.1-1.3 g/ml by taking calcium oxide and carbon dioxide as raw materials and adopting a step-by-step slurry retention carbonization synthesis process, ensures the product density and reduces the preparation cost.

The technical scheme of the invention is as follows: a preparation method of high-density calcium carbonate powder comprises the following steps:

1) mixing and stirring calcium oxide and hot water to prepare calcium hydroxide slurry, adjusting the concentration and temperature of the slurry, and removing impurities;

2) adding calcium hydroxide slurry with adjusted concentration and temperature into a carbonization tank, wherein the liquid level of the slurry is 20-50% of the height of the carbonization tank, starting a stirrer, introducing carbon dioxide gas to enable the calcium hydroxide and the carbon dioxide to generate a synthetic reaction, and gradually reducing the pH value of the slurry;

3) when the reaction is finished and the pH value of the slurry reaches 7, adding the calcium hydroxide slurry into the carbonization tank again until the pH value of the slurry reaches more than 13, stopping adding the calcium hydroxide slurry, uniformly stirring, and continuing the carbonization reaction to return the pH value of the calcium carbonate slurry to 7;

4) Continuously repeating the operation of the step 3) until the material level in the carbonization tank reaches 100 percent;

5) starting a slurry outlet pump to move the slurry with the pH value of 7 out of the carbonization tank until the slurry liquid level in the carbonization tank is 20-70%, and continuing the operation of the step 3);

6) Continuously repeating the step 5) under the condition that the calcium hydroxide slurry is enough until the pH value is 7 after the raw slurry is completely synthesized into the calcium carbonate particles, and cutting off the introduction of carbon dioxide gas; stopping stirring, and removing the calcium carbonate slurry;

7) dehydrating the calcium carbonate slurry by using a centrifugal machine to form a filter cake with 20-22% of water; the density of the filter cake is 2.3-2.5 g/ml;

8) Drying the filter cake until the water content is below 0.5%;

9) and beating the dried filter cake into powder by using a depolymerizer, and packaging to prepare the high-density calcium carbonate powder with the tap density of 1.1-1.3 g/ml.

preferably, the temperature of the hot water in the step 1) is 50-70 ℃, the concentration range of the calcium hydroxide slurry is 10-20 Baume degrees, and the temperature is 20-70 ℃.

preferably, the density of the filter cake prepared in the step 7) is 2.4 g/ml, and the density of the high-density calcium carbonate powder prepared in the step 9) is 1.2 g/ml.

Preferably, the density of the filter cake prepared in the step 7) is 2.3 g/ml, and the density of the high-density calcium carbonate powder prepared in the step 9) is 1.1 g/ml.

preferably, the density of the filter cake prepared in the step 7) is 2.5 g/ml, and the density of the high-density calcium carbonate powder prepared in the step 9) is 1.3 g/ml.

according to the invention, calcium oxide and carbon dioxide are used as raw materials, and a step-by-step slurry-remaining carbonization synthesis process is adopted to prepare the high-density calcium carbonate powder with the tap density of 1.1-1.3 g/ml, so that the product density is ensured, and the preparation cost is reduced.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

the present invention will be described in further detail with reference to the following drawings and examples, but the scope of the present invention is not limited thereto.

As shown in fig. 1, a method for preparing high-density calcium carbonate powder comprises the following steps:

1) Mixing and stirring calcium oxide and hot water to prepare calcium hydroxide slurry, adjusting the concentration and temperature of the slurry, and removing impurities;

2) Adding calcium hydroxide slurry with adjusted concentration and temperature into a carbonization tank, wherein the liquid level of the slurry is 20-50% of the height of the carbonization tank, starting a stirrer, introducing carbon dioxide gas to enable the calcium hydroxide and the carbon dioxide to generate a synthetic reaction, and gradually reducing the pH value of the slurry;

3) When the reaction is finished and the pH value of the slurry reaches 7, adding the calcium hydroxide slurry into the carbonization tank again until the pH value of the slurry reaches more than 13, stopping adding the calcium hydroxide slurry, uniformly stirring, and continuing the carbonization reaction to return the pH value of the calcium carbonate slurry to 7;

4) Continuously repeating the operation of the step 3) until the material level in the carbonization tank reaches 100 percent;

5) starting a slurry outlet pump to move the slurry with the pH value of 7 out of the carbonization tank until the slurry liquid level in the carbonization tank is 20-70%, and continuing the operation of the step 3);

6) continuously repeating the step 5) under the condition that the calcium hydroxide slurry is enough until the pH value is 7 after the raw slurry is completely synthesized into the calcium carbonate particles, and cutting off the introduction of carbon dioxide gas; stopping stirring, and removing the calcium carbonate slurry;

7) Dehydrating the calcium carbonate slurry by using a centrifugal machine to form a filter cake with 20-22% of water; the density of the filter cake is 2.3-2.5 g/ml;

8) Drying the filter cake until the water content is below 0.5%;

9) and beating the dried filter cake into powder by using a depolymerizer, and packaging to prepare the high-density calcium carbonate powder with the tap density of 1.1-1.3 g/ml.

In the step 1), the temperature of the hot water is 50-70 ℃, the concentration range of the calcium hydroxide slurry is 10-20 Baume degrees, and the temperature is 20-70 ℃.

The density of the filter cake prepared in the step 7) is 2.4 g/ml, and the density of the high-density calcium carbonate powder prepared in the step 9) is 1.2 g/ml.

According to the invention, calcium oxide and carbon dioxide are used as raw materials, and a step-by-step slurry-remaining carbonization synthesis process is adopted to prepare the high-density calcium carbonate powder with the tap density of 1.1-1.3 g/ml, so that the product density is ensured, and the preparation cost is reduced.