SU142837A1 - Soda-lime method for obtaining calcium chlorate-calcium defoliant (HHCD) - Google Patents

Description

The method for producing calcium chlorate-calcium defoliant (HHCD) by chlorinating soda-lime mixture with separating the precipitate of calcium carbopate is known and used in industry. The main disadvantage of the process is the production of a calcium carbonate by-product, the amount of which reaches 1.5 g per ton of CCD.

A method for the preparation of HXDs is proposed, in which the soda solution and milk of lime are subjected to separate or sequential chlorination, followed by evaporation of the mixture and separation of sodium chloride from the precipitated precipitate.

New in the proposal of the applicants is the replacement of the simultaneous chlorination of soda-lime mixture with separate or sequential chlorination of soda solution and milk of lime, followed by evaporation and separation of the sodium chloride precipitate.

The proposal is useful because it frees the process from calcium carbonate ballast and drastically reduces lime consumption and filtration losses.

According to the proposed method, a soda solution with a content of 105-PO of normal divisions of Ma2COz and lime milk with a content of 90-105 normal divisions of CaO is chlorinated in the x-chlorinators tower separately or sequentially in one chlorinator before the formation of chlorate.

In the case of separate chlorination, the chlorate liquors obtained from the chlorination of soda solution and milk of lime, after their preliminary neutralization (decomposition of the remaining hypochlorite) and filtration of calcium chlorate liquors, are mixed at a specific dosage.

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When this solution is evaporated, it is enriched with chlorate kg-inorganic for loss of sodium chloride. Calcium chloride has. a squeezing effect on sodium chloride, as a result of the end of evaporation, 98% of Na is released and remains

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mother liquor, available the ratio of pH is not less than 1.5 when the content

Ca (C1Oz) 2 not less than 420 g / l, which is responsible for the technical specifications of the drug HHKD.

To obtain a solution that meets the specifications for HHKD, an appropriate dosage of the initial solutions must be observed. The dosage of chlorate solutions is carried out according to the following equation:

1.7 / Caca1O ,,, g ,,

 - where: 1 / sa and l / f.g. - Volumes (m) of calcium and sodium chlorate liquors to be shifted; NaClOs, CaCi, (С10з) 2, content of NaUcSa, CaClF and Ca (C103) 2

in the original liquors, g / l

When sequentially chlorinating in one chlorinator, soda solution is first chlorinated and then milk of lime mixed with previously chlorinated lye. At the end of the chlorination, the schlobs are neutralized, filtered and evaporated to form a preparation. For this case, apply the following equation for dosage and components:

(OH -0.59. 1 / ,,,

where 1 / ca (OH) 2 NaoCO., are the volumes of the initial solutions of soda and ..CO. Ca (OH) -, - the concentration of soda and lime in the normalized method of HHCD production, using the same raw materials as the existing method - soda solution and milk of lime - eliminates the formation of calcium carbonate. This allows production with a very small amount of insoluble sludge (a certain amount of sludge is applied only with viskum milk) 15–20 kg per 1 m of weak liquor versus 300 kg per 1 m using the existing method. This dramatically reduces labor costs for filtration of liquor and loss of chlorate at the filtration stage.

The soda consumption in the new method is theoretically equal to the soda consumption in the old method, but reducing chlorate losses reduces soda consumption.

Lime consumption in the new method is three times less than in the old one.

Example. Sequential chlorination.

A 1 liter soda solution containing 105 normal divisions per liter of KA2SO3 (280 g / l) is poured into the chlorinator flask, which is chlorinated to obtain chlorate. The outward sign-disappearance of the sodium bicarbonate precipitate, which is formed as a result of the interaction of COj released from decomposition of soda soda with still not decomposed soda.

After the bicarbonate precipitate disappears, 690 ml of milk of lime containing 90 normal CaO 166 g / l Ca (OH) 2 divisions are added to the flask and continue to be chlorinated until the temperature rises. The solution becomes pink. lead (m); maximum divisions.

Chlorinated without cooling the reaction mass. Chlorinated liquors are treated with a small amount of sodium sulfide to decompose the remaining hypochlorite (1.5-2 g / l) and filter. Transparent, bleached liquors evaporated.

The filtered liquors contain: Ca (C103) 2-77 g1l, CaCI-55 g / l, NaCl-162g / l.

In the process of evaporation of such a solution, 158 g1 l of sodium chloride is liberated and a solution containing: Ca (C1O3) 2 not less than 420 g / l, CaCl-ZOOg / l, NaCl-25-30 g / l is obtained. СЮ-з / С --1,6, df -1,5, which answers the technical specifications for the drug HHKD.

Subject invention

The soda-lime method according to pupils of calcium chlorate-calcium defoliant (HHCD) by chlorination using evaporation, characterized in that the soda solution and lime milk are subjected to separate or sequential chlorination, followed by evaporation and separation of the precipitated sodium chloride precipitate.

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