RU2547105C2 - Method of joint obtaining calcium chloride and carbon dioxide - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. Method of joint obtaining calcium chloride and carbon dioxide includes interaction of calcium-containing raw material, including calcium carbonate, with 20-36% hydrochloric acid, supplied in doses. Formed solution of calcium chloride CaCl₂ is passed through calcium carbonate CaCO₃ and/or limestone flour, with formed carbon dioxide being passed through CaCO₃ or limestone flour and CaCl₂. Calcium-containing raw material is subjected to interaction with 20-36% hydrochloric acid first at temperature 20-40°C with the following increase of temperature to 55-70°C. Molar ratio CaCO₃ : HCl constitutes 1 : (1.8-2.2). Molar ratio of CaCO₃ or limestone flour and CaCl₂ constitutes 1 : (1-3).

EFFECT: invention makes it possible to increase process productivity, reduce release of harmful substances into atmosphere and sewage waters.

11 cl, 2 dwg, 3 tbl, 10 ex

Description

The invention relates to the production of calcium chloride and carbon dioxide for the production of sodium carbonate, which are widely used in the chemical, oil and chemical pharmaceutical industries, specifically in the production of barium chloride, drying gases, soaps and other detergents, when cooking pulp, for processing bauxite in aluminum production and as a charge in glass production, etc.

A known method of producing calcium chloride from a distillation liquid of soda production in adiabatic evaporators (SU 842024, publ. 30.06.1981).

The disadvantages of this method are high energy costs, the product contains a significant amount of sodium chloride, impurities and other metals.

A known method of producing calcium chloride by the interaction of hydrochloric acid with solid calcium carbonate in a closed lined vertical cylindrical reactor (FR 2446255, publ. 08.08.1980).

The disadvantages of this method are the low quality of the finished product, the lack of specific process parameters.

The closest in technical essence to the claimed method for producing calcium chloride is a method for producing calcium chloride (RU 2291109, publ. 10.01.2007), which includes the interaction of calcium-containing raw materials with hydrochloric acid at 20-50 ° C, 20-37% are dosed to calcium-containing raw materials hydrochloric acid at a molar ratio of CaCO ₃ : HCl = 1: 2, followed by passing the resulting acidic CaCl ₂ solution through CaCO ₃ and the resulting acidic carbon dioxide through CaCO ₃ and CaCl ₂ , taken in a 1-4: 1 molar ratio.

The disadvantage of this method is the low productivity in the production of both calcium chloride and carbon dioxide. Other disadvantages of this method are flooding the reactor with the supply of hydrochloric acid from the bottom up, increased foaming and delayed release of CO ₂ .

The objective of the present invention is to develop a method for the joint production of calcium chloride and carbon dioxide for the production of sodium carbonate and a technological scheme, increasing the productivity of the technological process, utilization of all types of gas and technical hydrochloric acids, the possibility of using all types of natural calcium-containing raw materials, calcium-containing waste and sludge, a significant reduction emission of harmful substances into the atmosphere and wastewater.

The above technical result of obtaining calcium chloride (hereinafter - CaCl ₂ ) and carbon dioxide (hereinafter - carbon dioxide, CO ₂ ) is achieved by the fact that calcium-containing raw materials (for example, natural calcium-containing raw materials selected from calcite, aragonite), including calcium carbonate, are subjected to interaction with 20-36% hydrochloric acid (hereinafter referred to as HCl) supplied in dosage, followed by passing the formed acidic solution of calcium chloride CaCl ₂ through calcium carbonate CaCO ₃ and / or limestone flour and the resulting carbonic acid gas through CaCO ₃ or limestone flour and CaCl ₂ taken in a molar ratio of 1: 1-3, respectively, the interaction is carried out for 1.5-2.5 hours, first at a temperature of 20-40 ° C, followed by a temperature increase to 55-70 ° C in two or more heated reactors with or without a mixing device. The molar ratio of CaCO ₃ : HCl is taken to be 1: 1.8-2.2, and the interaction may be carried out in the presence of an acid corrosion inhibitor. The supply of aqueous solutions of hydrochloric acid with a concentration of less than 25% or more than 32% is mainly carried out in the lower part of the reactors, and the supply of aqueous solutions of inhibited hydrochloric acid with a concentration of 25-32% is in the upper part of the reactors.

Inhibitors based on polyamines and benzyl chloride or based on polyamines (polypropylenepolyamines), carboxylic acids and benzyl chloride or imidazoline obtained by the reaction of polyamines with monocarboxylic acids, followed by its interaction with benzyl chloride in the presence of alcohol or acid amides are used as acid corrosion inhibitors. obtained from polyamines, oleic acid and benzyl chloride (RU 2350689, publ. 03/27/2009, RU 2347853, publ. 02/27/2009, RU 2357006, publ. 05/27/2009, RU 2347852, publ. 02/27/2009) in the amount of 0 , 01-0.1% by weight of calcium carbonate contained in calcium-containing raw materials.

Figure 1 shows a schematic diagram of reactors 1 and 2, where:

12 - a cover; 13 - heating tubes; 14 - a glass; 15 - mixer; 16 - fittings loading raw materials; 17 - fittings for unloading; 18 - thermocouple; 19 - case; 20, 21 - direction of flows.

I - calcium-containing raw materials; II - inhibited hydrochloric acid solution; III - weakly concentrated or concentrated inhibited hydrochloric acid; V is an insoluble precipitate; VI - CaCl ₂ + H ₂ O + HCl.

In figure 2. depicts a schematic diagram of the production of calcium chloride and carbon dioxide, where:

1-3 - reactors; 4 - a collection of insoluble precipitate; 5, 7 - capacity for CaCl ₂ ; 6 - column for the purification of CO ₂ ; 8 - pump; 9 - droplet eliminator; 10 - fan; 11 - desiccant with fused CaCl ₂ for drying CO ₂ .

I - natural calcium-containing raw materials, secondary calcium-containing raw materials or calcium-containing waste; II - inhibited hydrochloric acid solution; III - concentrated or concentrated inhibited hydrochloric acid; V is an insoluble precipitate; VI - CaCl ₂ + H ₂ O + HCl; VII - calcium carbonate or limestone flour; VIII - CO ₂ + HCl; IX - an aqueous solution of CaCl ₂ ; X - CaCl ₂ for evaporation, drying or in the granulator; XI is CO ₂ ; XII - CO ₂ to the atmosphere; XIII - СО ₂ for the production of soda ash; XIV - CO ₂ for the production of sodium carbonate from caustic soda; XV - CO ₂ for the production of chalk.

The proposed method is carried out by the interaction of calcium-containing raw materials (all types of natural limestone: calcite, aragonite, etc., limestone flour, calcium-containing waste and sludge) with hydrochloric acid in the reactors (1-3), a glass 14 is mounted inside the reactors (1,2) , in the lower part of which a grating is placed - a sieve (not indicated in the drawing), designed to hold solid particles of calcium carbonate. Raw materials are loaded into reactor 1 and 2, hydrochloric acid is metered into the upper part of the reactors. With this flow, the reaction (temperature 20-40 ° C) proceeds smoothly, and the formation of calcium chloride CaCl ₂ and the evolution of carbon dioxide. As the reaction proceeds, the resulting CaCl ₂ solution gradually moves down and CO ₂ is easily removed from above. The CaCl ₂ solution flows down, and the stirrer 15 (propeller) is turned on and heating to a temperature of 55-70 ° C is carried out. The resulting aqueous solution of CaCl ₂ with a small content of HCl is transferred from reactors 1 and 2 to a column reactor of type 3 (volume 5 l), filled with calcium carbonate (limestone flour), intended for additional production of calcium chloride and carbon dioxide.

Purification of the solution of calcium chloride from the residual content of hydrochloric acid as a result of the secondary reaction of calcium carbonate with hydrochloric acid is carried out in the reactor 3. In addition, CO ₂ and calcium chloride are additionally formed. The flow of CO ₂ and HCl from reactor 3 is combined with the flow of CO ₂ and HCl from the reactors (1, 2) and enters column 6 filled with calcium carbonate (limestone or limestone flour) and a solution of calcium chloride (26-32% concentration) in a ratio of 1: 1-3, respectively. In the production of soda ash (Na ₂ CO ₂ ), carbon dioxide (CO ₂ ) is obtained by decomposing limestone into calcium oxide (CaO) and carbon dioxide in kilns at a temperature of 900-1200 ° C.

In nature, there are several varieties of limestone: the most common are aragonite and calcite (Icelandic spar).

Aragonite in its structure is softer, and its decomposition temperature is 900-1200 ° С, and calcite decomposition temperature is 1600 ° С and more. There is a crushing and screening plant at Sterlitamak OJSC Soda where limestone is crushed and separated (Shah-Tau deposit ~ 6 km from Sterlitamak OJSC Soda). A fraction (50-150 mm) is used to produce carbon dioxide in kilns (45-50% of the total volume of limestone). The remaining part (50-55%) after sieving (calcite) is used as crushed stone in the construction of roads and as raw materials for cement production. When firing aragonite, carbon dioxide of only 37-39% concentration is formed.

The proposed method gives high-quality CO ₂ (its concentration is 95-98%) with 100% use of raw materials.

To protect the equipment, acid corrosion inhibitors can be used that protect the metal (equipment, apparatus, pipelines, etc.) obtained on the basis of polyamines and benzyl chloride (RU 2350689, publ. 03/27/2009), on the basis of polyamines (polypropylene-polyamines) , carboxylic acids and benzyl chloride (RU 2347853, publ. February 27, 2009), based on imidazolines obtained by the reaction of polyamines with monocarboxylic acids, followed by the interaction of the resulting imidazoline with chloride in the presence of alcohol (RU 2357006, publ. 27.05.2009), based amido in acids derived from polyamines, oleic acid and benzyl chloride (RU 2347852, publ. 02.27.2009) with a protective effect of 98.5-99.8%.

At a concentration of hydrochloric acid of 20% or lower, a supply of gaseous hydrogen chloride is provided together with hydrochloric acid to reinforce the resulting weak solution of calcium chloride.

The method is illustrated by the following examples.

Example 1. In reactors 1 and 2 (the volume of each reactor is 5 l), in the lower part of which there is a sieve designed to hold solid particles of limestone, the calculated amount of limestone is loaded through their upper part, then 30% is dosed into the upper part of the reactors aqueous solution of HCl. The molar ratio of CaCO ₃ : HCl = 1: 2. The dosed supply of hydrochloric acid provides a relatively quiet interaction of the feed with hydrochloric acid. In case of violent reaction of CaCO ₃ with HCl, the acid supply is temporarily stopped, and in the normal course of the process, the acid supply is resumed. The reaction mixture is heated first at a temperature of 20 ° C for 1 hour, then at 55 ° C for 1.5 hours

At the end of the reaction of CaCO ₃ with HCl, a liquid stream (CaCl ₂ + H ₂ O + HCl solution) flows down from the top of the reactor glasses 1, 2, after which the stirrer 15 (400 rpm) is turned on and the reactors are heated to 55 ° C. When this occurs, the averaging of CaCl ₂ solutions and intensive removal of the residual amount of CO ₂ . Reactors 1, 2 can operate independently, of course this ensures not only a continuous process for producing CaCl ₂ and CO ₂ , but, if necessary, a stop for repair of the reactor. The cascade of reactors of type 1 and 2 can be more than two in case of an increase in the production capacity of CaCl ₂ and carbon dioxide.

A stream of CaCl ₂ solution with a small content of hydrochloric acid from reactors 1 and 2 enters a column type reactor 3 filled with calcium carbonate or limestone flour, where CaCO ₃ reacts with a residual amount of HCl, resulting in additional formation of CaCl ₂ and CO _2, respectively. In reactor 3, the reaction rate of CaCO ₃ with HCl is accelerated by the use of limestone powder, because a small amount of HCl is contained in the CaCl ₂ solution stream and when using calcium carbonate (limestone), the reaction slows down.

The released carbon dioxide from reactor 3 is combined with a stream of CO ₂ from reactors 1, 2, then it enters column 6 (sanitary column) filled with calcium carbonate and 32% aqueous CaCl ₂ solution, taken in a 1: 1 molar ratio for guaranteed cleaning CO ₂ from HCl.

The experimental results are shown in table 1.

Example 2. Under the conditions of example 1, the calculated amounts of CaCO ₃ , 0.01% by weight of CaCO ₃ acid corrosion inhibitor are loaded into reactor 1 and 2, 31.5% hydrochloric acid are metered into the upper part of reactors 1 and 2 and after the overflow of the solution CaCl ₂ from the beaker into the reactor, the temperature of the reaction mixture was raised to 65-70 ° C and include a stirrer 15 (600 rpm). In this case, CO ₂ emission is enhanced and CaCl ₂ solution is taken from reactors 1 and 2 to reactor 3. The reaction mass in reactors 1 and 2 takes ~ 1.5–2.0 hours. After that, the slightly acidic CaCl ₂ solution passes through reactor 3 filled with CaCO ₃ or limestone flour (for quick reaction of CaCO ₃ with HCl).

To purify CO ₂ from HCl in column 6, a mixture of CaCO ₃ and 26% calcium chloride CaCl ₂ in a column in a molar ratio of CaCO ₃ : CaCl ₂ = 1: 2 are used.

The results of the experiments are given in table 1.

Example 3. Under the conditions of example 1, raw materials and 0.02% by weight of CaCO ₃ acid corrosion inhibitor are loaded into reactors 1 and 2, 36% hydrochloric acid is metered into the lower part of reactors 1 and 2, and a stirrer (800 rpm) is turned on. and heating to 60-65 ° C. The experiment time is 1.5 hours. A solution of CaCl ₂ from reactors 1 and 2 enters reactor 3 filled with limestone flour. Purification of CO ₂ occurs in column 6, filled in a molar ratio of CaCO ₃ : CaCl ₂ = 1: 3.

The experimental results are shown in table 1.

Example 4. Under the conditions of example 1, the calculated amounts of raw materials, an acid corrosion inhibitor (0.015% by weight of CaCO ₃ ) are loaded into reactors 1 and 2, and 27.5% hydrochloric acid is dosed. The reaction mass travels for 1.5 hours, then the reaction mass enters reactor 3 filled with CaCO ₃ , carbon dioxide is purified in column 6 (see Table 1).

Example 5. Under the conditions of example 1, the calculated amount of raw material, an acid corrosion inhibitor (0.02% of the mass of CaCO ₃ ), the molar ratio of CaCO ₃ : HCl = 1: 1.8, are loaded into reactors 1 and 2, dosed through the top of the reactors 25 % aqueous solution of hydrochloric acid HCl. They turn on the heating of reactors 1 and 2, the stirrer 15 (1000 rpm) and the reaction mixture is heated first at 40 ° C for 1 h, then at 70 ° C for 0.5 h, with a copious release of CO ₂ without noticeable foaming. The reaction time is 1.5 hours. After which, a solution of CaCl ₂ with a small amount of HCl enters the reactor 3 filled with CaCO ₃ , and the CO ₂ is purified in column 6.

The results of the experiments are given in table 1.

Example 6. Under the conditions of example 1, limestone (calcite, unsuitable for the production of soda ash), an acid corrosion inhibitor (0.015% by weight of CaCO ₃ contained in limestone) is loaded into reactors 1 and 2, a 34% aqueous HCl solution is dosed into the lower part of reactors 1 and 2, molar ratio of CaCO ₃ : HCl = 1: 2. In this case, a slight foaming occurs, but the dosage of hydrochloric acid does not stop. After heating is turned on, the reaction mixture is heated at 40 ° C for 1 hour, then at 70 ° C for 1 hour. The reaction time is 2 hours. Then, a stirrer 15 (800 rpm) is turned on and heating to 65-70 ° C. A solution of CaCl ₂ + HCl (slightly acidic) enters reactor 3, filled with CaCO ₃ and limestone flour (1: 1). Purification of CO _{2 is} carried out in column 6 filled with CaCO ₃ and CaCl ₂ in a molar ratio of CaCO ₃ : CaCl ₂ = 1: 1.5 (see table 1).

Example 7. Under the conditions of example 1, the calculated amount of feedstock, an acid corrosion inhibitor (0.01% by weight of CaCO ₃ in the feed) are loaded into reactors 1 and 2, 30% hydrochloric acid is dosed (molar ratio of CaCO ₃ : HCl = 1: 2.2) and at the end of the reaction include a stirrer 15 (1000 rpm) and heating to 65 ° C. The reaction time is 1.5 hours. After that, the slightly acidic CaCl ₂ solution enters the reactor 3 filled with CaCO ₃ . Purification of CO _{2 is} carried out in column 6 (see table 1).

Example 8. Under the conditions of example 1, the calculated amount of raw materials, a corrosion inhibitor (0.1% by weight of CaCO ₃ ) are loaded into reactors 1 and 2, 27% hydrochloric acid is metered into the upper part of reactors 1 and 2 (molar ratio of CaCO ₃ : HCl = 1: 2), include a stirrer 15 (1200 rpm) and heating to 65 ° C. The reaction time is 1.5 hours. Then, the slightly acidic CaCl ₂ solution enters the reactor 3 filled with CaCO _3.

The results are shown in table 1.

Example 9. Under the conditions of example 1, the calculated amount of calcium-containing secondary raw materials (CaCO ₃ content of 88%), an acid corrosion inhibitor (0.08% by weight of CaCO ₃ ) are charged into reactors 1 and 2, 12% hydrochloric acid is dosed, include stirrer 15 (1000 rpm). The reaction time is 8 hours. After which the weakly acidic solution enters the reactor 3 filled with CaCO ₃ . Purification of CO _{2 is} carried out in column 6.

The results of the experiments are shown in table 1

Example 10. Under the conditions of example 1, the calculated amount of calcium-containing raw materials, an acid corrosion inhibitor (1.0% of the mass of CaCO ₃ ), 36% HCl without a dosed feed are loaded into reactors 1 and 2 (flooding of the reactor was observed, and then a further supply of hydrochloric acids stopped, then switched to a dosed supply of hydrochloric acid). After the reaction mixture entered the reactor 3. Purification of CO _{2 is} carried out in column 6.

The experimental results are shown in table 1.

Examples 1-8, provided that the process parameters are maintained, give a high result.

Examples 9, 10 indicate that a deviation from the stated process parameters leads to an increase in the duration of the process (8 hours) or to choking reactors, etc.

Description of the technological scheme for producing calcium chloride and carbon dioxide (figure 2).

In the reactors 1 and 2, limestone or calcium-containing secondary raw materials (waste, sludge, etc.) are fed from above via line I.

25-32% aqueous solutions of HCl II are metered into the upper part of reactors 1 and 2. To obtain more concentrated solutions of CaCl ₂ or when using hydrochloric acid of less than 25% concentration, it is provided to be supplied to the lower part of reactors 1 and 2, which also occurs in the case of a more concentrated solution of inhibited acid (> 32% concentration) III. A solution of CaCl ₂ VI, containing a small amount of HCl and a small amount of CO ₂ , is continuously fed into reactor 3 filled with CaCO ₃ and / or limestone flour VII. In reactor 3, the residual content of hydrochloric acid is neutralized:

CaCO ₃ + 2 HCl = CaCl ₂ + CO ₂ + H ₂ O.

As a result of this reaction, an additional amount of CaCl ₂ and CO _{2 are formed} . Insoluble sediment V - silicon compounds and mechanical impurities contained in limestone, and which can be used in road construction, are removed from the lower parts of reactors 1-3 to collector 4.

To obtain CaCl ₂ and СО ₂ , hydrochloric acid is used according to STP 6-01-08-105-96 “Hydrochloric acid from the exhaust gases of organochlorine production” 31.5% (premium), 30.5% (first grade), 27.5 % (second grade), as well as concentrated hydrochloric acid with a concentration of 36%, gas and technical hydrochloric acids with a concentration below 27.5%.

After rector 3, a solution of CaCl ₂ IX is fed into a container 5, after which a solution of CaCl ₂ X is fed for evaporation and drying, and then, if necessary, to a granulator.

Table 2 shows the dependence of the concentration of calcium chloride on the concentration of the initial hydrochloric acid.

Table 3 shows the requirements of STP 6-01-08-105-96 for hydrochloric acid.

Carbon dioxide VIII from reactors 1-3 enters a sanitary column 6 filled with calcium carbonate (limestone or limestone flour) and a solution of CaCl ₂ (26-32% concentration) VII in a molar ratio of CaCO ₃ : CaCl ₂ = 1: 1- 3 respectively.

Calcium chloride with traces of HCl and CO ₂ VI from the bottom of the column 6 enters the tank 7 or into the reactor 3.

Container 7 is provided with CaCl ₂ IX solution. The purified carbon dioxide is passed through a droplet eliminator 9 and a desiccant 11 with fused CaCl ₂ .

Carbon dioxide can be used in the production of soda ash XIII according to the ammonia method, sodium carbonate from caustic soda XIV or chemically precipitated chalk XV. If necessary (emergency stop, repair of technological devices, etc.) carbon dioxide is emitted by the fan 10 into the atmosphere.

Claims (11)

1. The method of co-production of calcium chloride and carbon dioxide by the interaction of calcium-containing raw materials, including calcium carbonate, with 20-36% hydrochloric acid supplied dosed, followed by passing the resulting acidic solution of calcium chloride CaCl ₂ through calcium carbonate CaCO ₃ and / or limestone flour and carbon dioxide formed through CaCO ₃ or limestone flour and CaCl ₂ , characterized in that the calcium-containing raw materials are reacted with 20-36% hydrochloric acid first at a temperature of 20-40 ° C followed by they increase the temperature to 55-70 ° C, while the molar ratio of CaCO ₃ : HCl is 1: (1.8-2.2), and the molar ratio of CaCO ₃ or limestone flour and CaCl ₂ is 1: (1-3) respectively. 2. The method according to p. 1, characterized in that the interaction is carried out in two or more reactors with heating. 3. The method according to p. 2, characterized in that the supply of aqueous solutions of hydrochloric acid with a concentration of less than 25% and more than 32% is mainly carried out in the lower part of the reactors. 4. The method according to p. 2, characterized in that the reactors are equipped with a mixing device. 5. The method according to p. 1, characterized in that the interaction of calcium-containing raw materials with 20-36% hydrochloric acid is carried out for 1.5-2.5 hours 6. The method according to p. 1, characterized in that use gas or technical hydrochloric acid. 7. The method according to p. 1, characterized in that as the calcium-containing raw materials use natural calcium-containing raw materials selected from calcite, aragonite, limestone flour, calcium-containing waste and sludge. 8. The method according to p. 7, characterized in that as the calcium-containing raw materials, mainly calcite is used. 9. The method according to p. 1, characterized in that it is possible to use acid corrosion inhibitors. 10. The method according to p. 9, characterized in that the inhibitors obtained are based on polyamines and benzyl chloride, or based on polyamines (polypropylene polyamines), carboxylic acids and benzyl chloride, or imidazoline obtained by the reaction of polyamines with monocarboxylic acid as inhibitors of acid corrosion. acids, followed by its interaction with benzyl chloride in the presence of alcohol or acid amides derived from polyamines, oleic acid and benzyl chloride. 11. The method according to p. 9 or 10, characterized in that the use of acid corrosion inhibitors in an amount of 0.01-0.1% by weight of calcium carbonate contained in the calcium-containing raw materials.

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