CN108101090B

CN108101090B - Preparation method of needle-shaped precipitated calcium carbonate

Info

Publication number: CN108101090B
Application number: CN201711449913.1A
Authority: CN
Inventors: 王中华; 郑岳军; 陈刚
Original assignee: Shanghai Calcium Carbonate Factory Co ltd
Current assignee: Shanghai Calcium Carbonate Factory Co ltd
Priority date: 2017-12-27
Filing date: 2017-12-27
Publication date: 2020-04-28
Anticipated expiration: 2037-12-27
Also published as: CN108101090A

Abstract

The invention relates to a preparation method of needle-shaped precipitated calcium carbonate, which comprises the following steps: (1) adding quicklime into warm water, stirring, filtering, and discharging residue to obtain calcium hydroxide slurry; (2) adding the calcium hydroxide slurry into a reaction vessel provided with a dispersing paddle; and filling carbon dioxide, adding calcium hydroxide slurry at proper time according to the carbonization rate, and adjusting the rate of filling carbon dioxide to obtain the aqueous slurry of the needle-shaped precipitated calcium carbonate. The method adopts a multi-stage carbonization method, when the carbonization rate of the previous stage reaction is less than 100%, the next stage reaction is started, and the filling rate of carbon dioxide gas is adjusted, so that the needle-shaped calcium carbonate is obtained; the preparation process is simple, the cost is low, and the application prospect is good.

Description

Preparation method of needle-shaped precipitated calcium carbonate

Technical Field

The invention relates to the field of calcium carbonate, in particular to a preparation method of needle-shaped precipitated calcium carbonate.

Background

Precipitated calcium carbonate may be prepared by charging carbon dioxide gas into a reaction vessel containing a calcium hydroxide slurry. The precipitated calcium carbonate crystals have a spindle shape, a cubic shape, a needle shape, a chain shape, a spherical shape, a plate shape and a quadrangular prism shape. These different crystalline forms of calcium carbonate can be produced by controlling the reaction conditions. The carbonization process generally gives a spindle shape. If a multi-stage carbonization method is adopted, namely when the carbonization rate of the previous stage reaction is 100 percent, the next stage reaction is started, and the obtained product is also in a spindle shape.

The spindle-shaped calcium carbonate is not regular in shape and uniform, and is mainly used in industries such as papermaking and the like.

Disclosure of Invention

The main object of the invention is to provide a method for preparing needle-shaped precipitated calcium carbonate, which adopts a multi-stage carbonization method, when the carbonization rate of the previous stage reaction is less than 100 percent, the next stage reaction is started, and the filling rate of carbon dioxide gas is adjusted, so as to obtain needle-shaped calcium carbonate; the preparation process is simple, the cost is low, and the application prospect is good.

The invention relates to a preparation method of needle-shaped precipitated calcium carbonate, which comprises the following steps:

(1) adding quicklime into warm water, stirring, filtering, and discharging residue to obtain calcium hydroxide slurry; dividing the calcium hydroxide slurry into five equal volumes, and adding one volume into a reaction vessel provided with a dispersing paddle;

(2) reaction in the 1 st stage: starting the dispersing paddle and filling carbon dioxide;

reaction in the 2 nd stage: when the carbonization rate of the slurry in the reaction container is 20% -30%, adding a part of calcium hydroxide slurry, and filling carbon dioxide for the second time;

reaction in the 3 rd stage: when the carbonization rate of the slurry in the reaction container is 45% -65%, adding a part of calcium hydroxide slurry, and filling carbon dioxide for the third time;

reaction in the 4 th stage: when the carbonization rate of the slurry in the reaction container is 45% -65%, adding one part of calcium hydroxide slurry, and filling carbon dioxide for the fourth time;

reaction in the 5 th stage: when the carbonization rate of the slurry in the reaction container is 62.21% -65%, adding one part of calcium hydroxide slurry, and filling carbon dioxide for the fifth time; until the carbonization rate of the slurry in the reaction vessel is 100%, and obtaining aqueous slurry of the needle-shaped precipitated calcium carbonate after the reaction is finished;

wherein, the carbonization rates of the reaction slurry of the 3 rd stage reaction and the 5 th stage reaction are increased in sequence.

Further, the concentration of the calcium hydroxide slurry in the step (1) is 200-210 g/L.

Further, the linear speed of the dispersing blade in the step (2) when being opened is 2-3 m/s.

Further, the rate of the first carbon dioxide charging in the step (2) is 0.004 liter/min based on each gram of dry calcium hydroxide added; the rate of the second carbon dioxide injection was 0.008 l/min per gram of dry calcium hydroxide added; the rate of the third carbon dioxide injection was 0.012 l/min per gram of dry calcium hydroxide added; the rate of the fourth carbon dioxide injection was 0.016 liters per minute per gram of dry calcium hydroxide added; the rate of the fifth carbon dioxide sparge was 0.020 liters per minute per gram of dry calcium hydroxide added.

Advantageous effects

The method adopts a multi-stage carbonization method, when the carbonization rate of the previous stage reaction is less than 100%, the next stage reaction is started, and the filling rate of carbon dioxide gas is adjusted, so that the needle-shaped calcium carbonate is obtained, the preparation process is simple, the cost is low, and the method has a good application prospect; the acicular nano calcium carbonate has the advantages of high whiteness, low production cost, high strength, good filling performance and the like, is expected to replace fiber materials such as glass, asbestos and the like and expensive whisker materials such as potassium titanate, titanium carbide (TiC) and the like, and is widely used in industrial fields such as papermaking, plastics, rubber, paint and the like.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is an SEM micrograph of the slurry in the reaction vessel after the reaction of the 1 st stage in example 1;

FIG. 2 is an SEM micrograph of the slurry in the reaction vessel after the reaction of stage 2 in example 1;

FIG. 3 is an SEM micrograph of the slurry in the reaction vessel after the reaction of stage 3 in example 1;

FIG. 4 is an SEM micrograph of the slurry in the reaction vessel after the reaction of stage 4 in example 1;

FIG. 5 is an SEM micrograph of the slurry in the reaction vessel after the stage 5 reaction of example 1.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions.

Example 1

(1) Adding 10892 g of quicklime into 40L of water with the temperature of 40 ℃ and stirring for 30 minutes to prepare calcium hydroxide slurry; the calcium hydroxide slurry was passed through a 200 mesh standard sieve at a concentration of 200 g/l. Calcium hydroxide slurry 8 liters was added to the reaction vessel.

(2) Reaction in the 1 st stage: the dispersing blade was started (line speed 2.5 m/s), carbon dioxide was charged (rate 6.4 l/min), and a micrograph of the reaction product is shown in FIG. 1. from FIG. 1, a prototype of needle-shaped calcium carbonate was obtained, but the aspect ratio was still small; when the carbonization rate of the slurry in the reaction vessel was 26.1%,

reaction in the 2 nd stage: then, calcium hydroxide slurry 8 was added thereto, the rate of carbon dioxide introduction was adjusted to 12.8 liters/min, and a photomicrograph of the reaction product is shown in FIG. 2, from which it is understood that needle-like calcium carbonate had appeared; when the carbonization rate of the slurry in the reaction vessel was 47.4%,

reaction in the 3 rd stage: then adding calcium hydroxide slurry 8L to the reaction vessel, the carbon dioxide charging rate was adjusted to 19.2L/min, and the microphotograph of the reaction product is shown in FIG. 3. As can be seen from FIG. 3, the length-diameter ratio of the needle-like calcium carbonate is very large, and the point length can reach several micrometers. When the carbonization rate of the slurry in the reaction vessel is 59.5%,

reaction in the 4 th stage: then, calcium hydroxide slurry 8 was added thereto, the rate of carbon dioxide introduction was adjusted to 25.6 liters/min, and a photomicrograph of the reaction product was shown in FIG. 4, from which it was found that needle-like calcium carbonate gradually grew. When the carbonization rate of the slurry in the reaction vessel is 62.21%,

reaction in the 5 th stage: then adding 8 liters of calcium hydroxide slurry into the reaction vessel, and adjusting the rate of filling carbon dioxide to 32 liters/minute; until the carbonization rate of the slurry in the reaction vessel is 100 percent. After the reaction, an aqueous slurry of needle-shaped precipitated calcium carbonate was obtained, and a micrograph of the reaction product was shown in FIG. 5. As can be seen from FIG. 5, the needle-shaped calcium carbonate had a large and uniform aspect ratio.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing needle-shaped precipitated calcium carbonate, comprising:

wherein, the carbonization rates of the 3 rd stage reaction-5 th stage reaction slurry are increased in sequence;

the rate of the first carbon dioxide charging in the step (2) is 0.004 liter/min based on each gram of dry calcium hydroxide added; the rate of the second carbon dioxide injection was 0.008 l/min per gram of dry calcium hydroxide added; the rate of the third carbon dioxide injection was 0.012 l/min per gram of dry calcium hydroxide added; the rate of the fourth carbon dioxide injection was 0.016 liters per minute per gram of dry calcium hydroxide added; the rate of the fifth carbon dioxide sparge was 0.020 liters per minute per gram of dry calcium hydroxide added.

2. The process for the preparation of needle-shaped precipitated calcium carbonate according to claim 1, characterized in that: the concentration of the calcium hydroxide slurry in the step (1) is 200-210 g/L.

3. The process for the preparation of needle-shaped precipitated calcium carbonate according to claim 1, characterized in that: the linear speed of the dispersing paddles in the step (2) is 2-3 m/s when the dispersing paddles are started.