CS240523B1 - The method of producing the leaching solution - Google Patents

Abstract

From a solution of a calcium salt of an inorganic and/or organic acid (calcium chloride, calcium nitrate, calcium formate, calcium acetate, etc., but also wastewater containing the above salts), calcium carbonate is precipitated with a solution of an organic nitrogenous base carbonate and/or a solution of an organic nitrogenous base while simultaneously feeding carbon dioxide into the reaction system containing the above components. The method is suitable for the production of pure calcium carbonate from raw materials, including industrial waste, containing calcium oxide or hydroxide as the main component.

Description

SUMMARY OF THE INVENTION The present invention provides a process for the production of a leaching solution for the production of calcium carbonate from calcium oxide and / or hydrate products thereof, optionally using waste salts containing calcium salts. .

For leaching of calcium oxide and / or calcium hydroxide, it is preferred from low-grade calcium raw materials, e.g. from the carbide lime or the dusts and flakes containing at least the calcium oxide and / or calcium hydroxide, a salt or salts of inorganic and / or organic acids forming soluble calcium salts, preferably of hydrochloric acid (saline), nitric acid, formic acid and acetic acid, with an organic nitrogen base or bases, which preferably contain at least one hydroxyl group bonded to a carbon atom. These salts are conveniently prepared by standard procedures by neutralizing an inorganic and / or organic acid with an organic nitrogen base. However, this procedure requires the use of inorganic or organic acids, which necessitates special precautions from the point of view of occupational safety and breakdowns of the production facilities caused by the corrodes. -

According to the invention, there is provided a process for the production of a leaching solution consisting of salts of inorganic and / or organic acids forming soluble calcium salts with organic nitrogen bases for the production of calcium carbonate from raw materials and / or industrial wastes containing oxide and / or calcium hydroxide, is effected by precipitating calcium carbonate from a solution of an inorganic and / or organic acid calcium salt with a solution of an organic nitrogenous base carbonate and / or an organic nitrogenous base solution while feeding the carbon dioxide in a gaseous, dissolved or solid state to a reaction system containing said components.

An advantage of the process for producing the leaching solution of the present invention is the possibility of using calcium salts thereof in place of pure inorganic and / or organic acids which are corrosive, volatile and poisonous liquids. These are practically neutral, low corrosive, nonvolatile and nontoxic substances, technically readily available in solid form or in solution, often in the form of industrial wastes or by-products of various chemical products such as e.g. calcium chloride from trichlorethylene production by dehydrochlorination of tetrachloroethane, from propylene oxide production by the chlorohydrin process, calcium formate from pentaerythritol production and i.

Another advantage is the possibility of utilizing a wide variety of technically readily available nitrogen bases such as alkylamines and derivatives thereof, e.g. ethylenediamine (1,2-diaminoethane) Hanchi ₂ CH _{2 and} NH, piperidine C _g H ₁₀ NH, alkanolamines, and derivatives thereof, e.g. monoethanolamine {2-aminoethanol, 2-hydroxyaminoethane, 2-hydroxyethylamine) HOCH ₂ CH ₂ NH 2, diethanolamine (iminobis {2-ethanol)}, 1-amino-2-propanol (2-hydroxypropylamine, 2-hydroxyaminopropane) CH ₃ CH ( OH) CH 2 NH 2, 1,3-diamino-2-propanol (2-hydroxytrimethylenediamine)

H ₂ NCH ₂ CH (OH) CH ₂ NH 2 and i.

According to the invention, not only the intentionally produced compounds formed e.g. by the action of inorganic and / or organic acids on calcium compounds, in particular 0xid, calcium hydroxide or carbonate and the like, but also calcium salts of inorganic or organic acids, which are formed as by-products or industrial waste in various chemical processes, also in the presence of dissolved but mainly dispersed calcium hydroxide as well as admixtures of other inorganic and organic compounds.

The carbon dioxide for carrying out the process according to the invention can be supplied either in a pure state or in a mixture with other gases such as air, nitrogen, hydrogen, carbon monoxide, methane and the like, but also in the form of a saturated aqueous solution or solid carbon dioxide (so-called dry ice).

The process according to the invention can be carried out in a particularly discontinuous manner, but also in the form of a saturated aqueous solution or in the form of solid carbon dioxide (so-called dry ice).

The process according to the invention can be carried out in a particularly discontinuous, but also semi-continuous and continuous manner. Further details of the production process are apparent from the examples.

EXAMPLE

100 wt. parts of solid calcium formate are dissolved in 750 wt. parts of an aqueous solution containing 100 wt. parts of monoethanolamine. Carbon dioxide is added to the solution at 40 ° C until precipitation of calcium carbonate is complete, which is separated from the monoethanolamine formate solution by filtration. The monoethanolamine carbonate present in the solution is determined analytically and converted to monoethanolamine by adding a calculated amount of calcium oxide.

Example 2

Up to 100 wt. parts of an aqueous solution containing 17 wt. parts of calcium nitrate and 18 wt. Carbon dioxide (60% by volume mixed with air) is introduced at 30 ° C in portions of piperidine until the calcium carbonate is completely precipitated, which is separated from the piperidine nitrate solution by filtration. The piperidine carbonate present in the solution is determined analytically and removed by adding the calculated amount of calcium nitrate.

EXAMPLE 1 a d 3

Up to 100 wt. parts of an aqueous solution containing 26 wt. parts of monoethanolamine saturated with carbon dioxide (pH of solution 7.5) is added at 20 ° C with stirring of 100 wt. % of calcium chloride (24% CaCl ₂ content). The precipitated calcium carbonate solution is separated from the resulting monoethanolamine chloride solution by filtration.

Example 4

100 wt. parts of solid calcium acetate are dissolved in 300 wt. parts of water 25 ° C warm and to this solution is added, under stirring, a solution prepared by reacting diethanolamine (125 parts by weight) dissolved in water (150 parts by weight) with solid carbon dioxide (final pH of solution 8) until complete precipitation of calcium carbonate which is separated from the solution of the resulting diethanolamine acetate by filtration.

Example 5

Up to 100 wt. parts of an aqueous solution containing 37.7% by weight monoethanolamine saturated with carbon dioxide (pH of solution 7.5) are added at 25 ° C with stirring, 652% by weight. parts of waste water from propylene oxide production by the chlorohydrin process comprising 3.68% by weight of calcium chloride, 0.80% by weight of calcium hydroxide, and 0.145 pens. weight of propylene glycol together with 16 weight parts of industrial hydrochloric acid at a concentration of 31% / weight of HCl.

A mixture of carbon dioxide (70% by volume) and carbon monoxide was added to the resulting solution until the calcium carbonate precipitated completely. The precipitated calcium carbonate solution is separated from the resulting monoethanolamine chloride solution with the addition of propylene glycol by filtration.

Claims (1)

A process for the production of a leaching solution consisting of salts of inorganic and / or organic acids forming soluble calcium salts with organic nitrogen bases for the production of calcium carbonate from raw materials and / or industrial wastes containing as main constituent calcium and / or calcium hydroxide, that OF THE INVENTION calcium carbonate is precipitated from a solution of an inorganic and / or organic acid calcium salt with a solution of an organic nitrogenous base, while feeding the carbon dioxide in gas, but dissolved. or solid state into a reaction system containing said components.