RU2489355C2 - Method for synthesis of finely dispersed calcium carbonate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. The method for synthesis of finely dispersed calcium carbonate involves reaction of calcium hydroxide with carbon dioxide in an aqueous medium. Before reacting with carbon dioxide, calcium hydroxide is dispersed in a solution containing either ammonium salts selected from a group comprising ammonium chloride, ammonium nitrate, or saccharose with concentration of 4-30% and surfactants in amount of 0.01-5% per mass of the starting calcium hydroxide.

EFFECT: invention enables to obtain finely dispersed calcium carbonate.

12 tbl, 12 ex

Description

The invention relates to chemical technology, in particular to the production of highly dispersed calcium carbonate CaCO ₃ , calcium carbonate, which is an extremely important intermediate for various chemical and other industries.

In particular, these are:

1) the basis for white oil paint and other types of oil paints;

2) filler for paper, linoleum, rubber;

3) filler for thermoplastic plastics - the basis for the production of soft containers;

4) the necessary component is a combustion retardant and an element of heat-shielding coatings in the production of pyroxylin, ballistic powders, mixed solid rocket fuels and other special-purpose products;

5) the basis for whitewashing, tinting in the construction business.

Today, there are two main sources of calcium carbonate:

1) natural calcium carbonate obtained from Cretaceous quarries;

2) calcium carbonate - a by-product in the production of mineral fertilizers. In particular, calcium carbonate, being a by-product of a number of production of complex mineral fertilizers (Kirovo-Chepetsk chemical plant, Rossoshansky chemical plant, Akron plant), today without movement lies in the territories and landfills of dumps of these enterprises, littering the surrounding Wednesday

However, calcium carbonate, both “quarry” and “by-product” of mineral fertilizer plants, has too large a source particle size of 100-200 microns. In view of this, its use is limited, since the above industries in paragraphs 1-5 cannot use such a product due to too large particles. As a result, a competitive level of quality is not achieved above the specified types of products and substances.

Therefore, calcium carbonate is subject to grinding from particles with a diameter of 200-200 microns to 4-5 microns, in some cases up to 1-0.8 microns.

Various methods are known for producing finely divided calcium carbonate. So, 1960, pp. 8-18) there is a known method [1] (A.G. Kasatkin. The main processes and apparatuses of chemical technology. M .: consisting in the fact that calcium carbonate is milled in mills of various designs. The disadvantages of this method is a large energy consumption, the unevenness of the obtained product according to particle size distribution.In addition, when implementing this method, all extraneous cations and anions contained in the original natural calcium carbonate, or in calcium carbonate - waste in the production of mineral fertilizers, stored, which negatively affects the whiteness and other product characteristics desired product - finely divided calcium carbonate.

The known method [2] (Yu.V. Koryakin, II Angelov. Pure chemicals. M: 1971, p.152-153), which consists in mixing solutions of ammonium carbonate and calcium nitrate followed by filtering the precipitate. The precipitate of calcium carbonate obtained in this way is sucked off in a Buchner funnel and washed on the filter with a slow stream of water. The disadvantage of this method is the production of calcium carbonate with different particle diameters from 50 μm to 5 μm, smaller particles cannot be obtained.

A known method of complex processing of gypsum waste [3] (V. A. Kolokolnikov, V. M. Titov, A. A. Shatov. RF patent №2258036, 06/09/2004 - Method for the complex processing of phosphogypsum), the execution of which yields calcium carbonate. However, when implementing this method, it is not possible to obtain highly dispersed calcium carbonate, the method is extremely cumbersome and expensive to perform.

The most closely posed problem meets the method of producing calcium carbonate by reacting calcium hydroxide in an aqueous solution with carbon dioxide [4] (ME Pozin. Technology of mineral salts. 1960, p. 530-532). According to the known method, calcium hydroxide is dispersed in water and carbon dioxide is bubbled into this dispersion until the pH of the reaction medium changes from very alkaline to neutral. Next, the suspension of calcium carbonate is filtered off and dried. However, when implementing this method, coarse calcium carbonate is formed.

The task of the invention is to obtain highly dispersed calcium carbonate. The goal is achieved as described below: including the interaction of calcium hydroxide with carbon dioxide in an aqueous medium, characterized in that before the interaction with carbon dioxide, calcium hydroxide is dispersed in a solution containing either ammonium salts from the group - ammonium chloride, ammonium nitrate, or sucrose in concentration from 4% to 30% and surfactants in an amount of from 0.01% to 5%, based on the weight of the initial calcium hydroxide.

Dispersion of calcium hydroxide in the inventive salt solutions: ammonium chloride or ammonium nitrate and / or in a sucrose solution and the introduction of surfactants when implementing the proposed method before reacting the reactants in the claimed quantitative ratios is a hallmark of the claimed invention.

Thanks to the implementation of this method, it is possible to synthesize highly dispersed calcium carbonate, which has very large and demanded sales segments. The essence of the claimed invention is presented in the examples of specific performance.

Example 1. A portion of calcium hydroxide is dispersed in a solution of ammonium chloride NH ₄ Cl in the claimed concentrations, based on the weight of the source of calcium hydroxide. After dispersion, an anionic surfactant, alkyl sulfonate, is introduced into the pulp — a mixture of sodium salts of alkyl sulfonic acids obtained from n-paraffins at a concentration of 2.5% based on the weight of the initial calcium hydroxide. Table 1 presents information on the implementation of experiments in the claimed concentrations of ammonium chloride. The same table provides the results of the experiment - the properties of calcium carbonate according to the prototype and the claimed method.

Table 1 The concentration of the solution of ammonium chloride NH ₄ Cl,% Prototype without NH ₄ Cl 3% four% 17% thirty% 32% Indicators 1. Conversion,% 91 91 93 95 98 98 2. White,% 90 90 91 93 95 95 3. The average particle size, microns fourteen fourteen 4.3 1,5 1.4 1.4

Analysis of the obtained data allows us to state that in the synthesis of calcium carbonate by the proposed method, finely dispersed calcium carbonate is obtained, superior to the product obtained by the prototype. When using ammonium chloride when using a concentration of ammonium chloride above 30% there is no advantage in the characteristics of calcium carbonate, and the efficiency of the synthesis process is reduced; when using a concentration of less than 4%, the properties of calcium carbonate and its degree of dispersion deteriorate.

Example 2. A portion of calcium hydroxide is dispersed in an aqueous solution of ammonium nitrate in the claimed concentrations and the prototype. A surfactant is introduced cationic bis-quaternary ammonium derivative of an aliphatic structure at a concentration of 2.5% by weight of the original calcium hydroxide. Table 2 presents the experimental results depending on the dispersion of calcium hydroxide in aqueous solutions with different concentrations of ammonium hydroxide.

table 2 The concentration of the solution of ammonium nitrate NH ₄ NO ₃ ,% Prototype without dispersion in the inventive solution 3% four% 17% thirty% 32% Indicators 1. Conversion,% 90 90 92 97 98 98 2. White,% 89 90 95 96 96 96 3. The average particle size, microns eighteen eighteen 12 3 1,1 1,1

Analysis of the obtained data allows us to state that when implementing the conversion of calcium hydroxide by the proposed method, finely dispersed calcium carbonate is obtained that is superior to the product of the prototype. As in the case of Example 1, going beyond the stated concentration limits leads to a deterioration: above 30% NH ₄ NO ₃ in an aqueous solution there are no advantages in the characteristics of calcium carbonate and the efficiency of the process decreases, below 4%, the properties of calcium carbonate deteriorate.

Example 3. A portion of calcium hydroxide is dispersed in an aqueous solution of sucrose in the claimed concentrations and the prototype. A nonionic surfactant is introduced - ethoxylated monoalkylphenols at a concentration of 2.5% by weight of the initial calcium hydroxide. Table 3 presents the experimental results depending on the dispersion of calcium hydroxide in aqueous solutions with different concentrations of ammonium hydroxide.

Table 3 The concentration of sucrose solution,% Prototype without dispersion in the inventive solution 3% four% 17% thirty% 32% Indicators 1. Conversion,% 89 89 91 95 98 98 2. White,% 90 90 94 96 97 97 3. The average particle size, microns fourteen fourteen 9 2 0.8 0.8

Analysis of the obtained data also allows us to ascertain the presence of positive effects in comparison with the prototype. Going beyond the declared limits of the concentration of an aqueous solution of sucrose results in a loss of positive effects.

Example 4. A portion of calcium hydroxide is dispersed in an aqueous solution of ammonium chloride at a concentration of 17%. Anionic surfactant is introduced, as in example 1, in amounts from 0.01% to 5%, based on the weight of the initial calcium hydroxide. Table 4 presents the experimental results depending on the concentration of calcium hydroxide in a solution of NH ₄ Cl 17% concentration.

Table 4 The concentration of the introduced anionic surfactant,% on the initial Ca (OH) ₂ Prototype without surfactant 0.005% 0.01% 2.5% 5% 5.2% Indicators 1. Conversion, 88 90 96 97 98 98 % 90 92 95 96 96 96 2. White,% 13 10 four 1.3 0.9 0.9 3. The average particle size, microns

Example 5. A portion of calcium hydroxide is dispersed in an aqueous solution of ammonium chloride at a concentration of 17%. A surfactant is introduced, a cationic bis-quaternary ammonium derivative of an aliphatic structure as in Example 2, in amounts from 0.01% to 5%, based on the weight of the initial calcium hydroxide. Table 5 presents the experimental results depending on the concentration of calcium hydroxide in a solution of NH ₄ Cl 17% concentration.

Table 5 The concentration of the introduced anionic surfactant,% on the source Ca (OH) ₂ Prototype without
Surfactant 0.005% 0.01% 2.5% 5% 5.2% Indicators 1. Conversion,% 89 90 97 97 98 98 2. White,% 90 93 94 95 96 96 3. The average particle size, microns fifteen fourteen 9 2,5 1,0 1,0

Example 6. A portion of calcium hydroxide is dispersed in an aqueous solution of ammonium chloride at a concentration of 17%. The surfactant is introduced nonionic hydroxyethylated monoalkylphenols as in example 2, in amounts from 0.01% to 5%, based on the weight of the source of calcium hydroxide. Table 6 presents the experimental results depending on the concentration of calcium hydroxide in a solution of NH ₄ Cl 17% concentration.

Table 6 Concentration Prototype without 0.005% 0.01% 2.5% 5% 5.2% introduced anionic surfactant,% of the original Ca (OH) ₂ Surfactant Indicators 1. Conversion,% 88 89 94 95 96 96 2. White,% 90 90 95 97 97 97 3. The average particle size, microns twenty 19 7.5 3.0 0.7 0.7

Example 7. A portion of calcium hydroxide is dispersed in an aqueous solution of ammonium nitrate at a concentration of 17%. A nonionic surfactant is introduced, ethoxylated monoalkylphenols as in Example 2, in amounts from 0.01% to 5%, based on the weight of the starting calcium hydroxide. Table 7 presents the experimental results depending on the concentration of calcium hydroxide in a solution of NH ₄ Cl 17% concentration.

Table 7 The concentration of the introduced anionic surfactant,% on the initial Ca (OH) ₂ Prototype without surfactant 0.005% 0.01% 2.5% 5% 5.2% Indicators 1. Conversion,% 88 89 94 96 98 98 2. White,% 89 90 93 96 97 97 3. The average particle size, microns 12 10 four 1.3 0.8 0.8

Example 8. A portion of calcium hydroxide is dispersed in an aqueous solution of ammonium nitrate at a concentration of 17%. A surfactant is introduced anionic alkyl sulfonate — a mixture of sodium salts of alkyl sulfonic acids obtained from n-paraffins as in Example 1, in amounts of from 0.01% to 5%, based on the weight of the initial calcium hydroxide. Table 8 presents the experimental results depending on the concentration of calcium hydroxide in a solution of NH ₄ Cl 17% concentration.

Table 8 The concentration of the introduced anionic surfactant,% on the initial Ca (OH) ₂ Prototype without surfactant 0.005% 0.01% 2.5% 5% 5.2% Indicators 1. Conversion,% 90 90 94 96 98 98 2. White,% 89 90 92 96 97 97 3. The average particle size, microns fifteen fifteen 6 2 0.7 0.7

Example 9. A portion of calcium hydroxide is dispersed in an aqueous solution of ammonium nitrate at a concentration of 17%. A cationic surfactant is introduced as in Example 2, in amounts from 0.01% to 5%, based on the weight of the starting calcium hydroxide. Table 9 presents the experimental results depending on the concentration of calcium hydroxide in a solution of NH ₄ Cl 17% concentration.

Table 9 The concentration of the introduced anionic surfactant,% on the initial Ca (OH) ₂ Prototype without surfactant 0.005% 0.01% 2.5% 5% 5.2% Indicators 1. Conversion, 89 89 92 95 97 97 % 90 91 92 95 96 96 2. White,% 16 16 8 3 0.7 0.7 3. The average particle size, microns

Example 10. A portion of calcium hydroxide is dispersed in an aqueous solution of sucrose at a concentration of 17%. A cationic surfactant is introduced as in Example 2, in amounts from 0.01% to 5%, based on the weight of the starting calcium hydroxide. Table 10 presents the experimental results depending on the concentration of calcium hydroxide in a solution of NH ₄ Cl 17% concentration.

Table 10 The concentration of the introduced anionic surfactant,% on the initial Ca (OH) ₂ Prototype without surfactant 0.005% 0.01% 2.5% 5% 5.2% Indicators 1. Conversion,% 88 89 94 98 98 98 2. White,% 87 88 95 96 96 96 3. The average particle size, microns fifteen 13 3,5 1,5 0.7 0.7

Example 11. A portion of calcium hydroxide is dispersed in an aqueous solution of sucrose at a concentration of 17%. Anionic surfactant is introduced as in Example 1, in amounts from 0.01% to 5%, based on the weight of the initial calcium hydroxide. Table 11 presents the experimental results depending on the concentration of calcium hydroxide in a sucrose solution of 17% concentration.

Table 11 The concentration of the introduced anionic surfactant,% on the initial Ca (OH) ₂ Prototype without surfactant 0.005% 0.01% 2.5% 5% 5.2% Indicators 1. Conversion,% 88 89 94 95 97 97 2. White,% 90 90 93 95 96 97 3. The average particle size, microns 16 fifteen 5 1,5 0.8 0.8

Example 12. A portion of calcium hydroxide is dispersed in an aqueous solution of sucrose at a concentration of 17%. A nonionic surfactant is introduced as in Example 3, in amounts from 0.01% to 5%, based on the weight of the starting calcium hydroxide. Table 12 presents the experimental results depending on the concentration of calcium hydroxide in a sucrose solution of 17% concentration.

Table 12 The concentration of the introduced anionic surfactant,% on the initial Ca (OH) ₂ Prototype without surfactant 0.005% 0.01% 2.5% 5% 5.2% Indicators 1. Conversion,% 89 90 94 95 96 96 2. White,% 90 90 93 93 95 95 3. The average particle size, microns fifteen fourteen four 1,5 0.7 0.7

Thus, from the presented examples, it is obvious that a positive effect is obtained in the synthesis of finely divided calcium carbonate according to the claimed method. The implementation of the proposed method will allow to obtain a valuable and sought-after product for various industries. The economic efficiency of this method consists in the fact that for 1 ton of the initial calcium hydroxide, the sales amount obtained when selling highly dispersed calcium carbonate is at least 15 thousand rubles. per ton.

Claims (1)

A method of synthesizing highly dispersed calcium carbonate, comprising reacting calcium hydroxide with carbon dioxide in an aqueous medium, characterized in that before reacting with carbon dioxide, calcium hydroxide is dispersed in a solution containing either ammonium salts from the group of ammonium chloride, ammonium nitrate, or sucrose in a concentration of 4 % to 30% and surface-active substances (surfactants) in an amount of from 0.01% to 5%, based on the weight of the initial calcium hydroxide.