SU1046346A1 - Method for regenerating waste fluorinaceous solutions - Google Patents

Abstract

A METHOD FOR THE REGENERATION OF FINISHED FLUORO-CONTAINING TRACULAR PLANTS, including the introduction of acetone, the separation of sediment and distillation of acetone, characterized in that, in order to increase the efficiency of the regeneration process, before the introduction of acetone, phosphoric acid in a ratio of 1-1.5 to iron is introduced into the solution, and acetone administered in a ratio of 2: 1 to 4tl to the volume of the solution. Cl

Description

The invention relates to the processing of fluorine-containing etching solutions of metallurgical production and can also be used in the engineering industry.

The known method, according to which the spent fluorine-containing solutions are neutralized with lime or lime milk 1.

However, all valuable components of the pickling solution are completely lost, as the sediment enters the dump,

The closest to the proposed technical essence is the method, which consists in introducing acetone, methanol, or their mixture at 40 s into the aqueous solution obtained, for example, during hydrometallurgical processes and containing soluble sulfates. These substances reduce the activity of water as a solvent, with the result that heavy metals precipitate as salts 2.

The disadvantages of this method are the low degree of regeneration of fluorine and the insufficient efficiency of removing iron from spent solutions.

The object of the invention is to increase the efficiency of the regeneration process.

The goal is achieved. According to the method of regeneration of spent fluorine-containing etching solutions, including the introduction of acetone, the separation of the precipitate and the distillation of acetone, before the introduction of acetone, phosphoric acid is introduced in a ratio of 1 to 1.5 to iron, and acetone is introduced in a ratio of 2: 1 - 4: 1 by volume of solution.

The method is carried out as follows. .

Phosphoric acid in the amount of 1-1.5 of stoichiometry calculated for iron is introduced into the spent fluorine-containing pickling solution, then the solution is treated with acetone in a ratio of 2: 1 - 4: 1 v / v of pickling solution at a temperature of 50 ° C. The resulting suspension is settled for several hours, usually from 1 to 5 hours, after which the clarified layer of the solution is drained. The wet phosphates and metal fluorides separated in this way are filtered and dried at vlpS C.

Acetone is then distilled from the solution at 56-70 ° C, which is condensed and reused. The regenerated solution is adjusted for acids and returned to the pickling bath.

Preliminary introduction in phosphoric acid solution

followed by treatment with acetone leads to an increase in the degree of fluorine regeneration and an increase in the effect of iron removal.

The introduction of phosphoric acid in the spent fluoroso5 solution leads to the binding of iron ions with phosphate ions to the formation of iron phosphate precipitate. As a result, iron fluoride

0 and fluoride ions are released. But these processes, in the absence of acetone, are inactive due to the high strength of the fluorocomplexes of iron and the high activity of water as a solvent. The addition of acetone in the amount of 2: 1 - 4: 1 with respect to the volume of the solution leads to a sharp decrease in water activity as a solvent, i.e. causes salting out effect. Phosphates and fluorides of iron, chromium and nickel precipitate.

Example 1. .50 ml of the spent solution of the composition with the acidity of 0.79 g - eq / l, containing, g / l:. Fe3 + 43.4; , 4:, 4; Fe 57, l

with a temperature of 20 ° C is treated

100 ml of acetone with vigorous stirring for 10 minutes and assert within 4 hours. The clarified layer of the solution is drained and the wet

0 the precipitate is filtered off from the remnants of the mother liquor and dried at. The moisture content of the precipitate is 40%. Acetone g is distilled from the solution at 56-70 s. The degree of distillation 98%.

5 Get 47.5 ml of regenerate. The composition of the regenerate with an acidity of 0.6 g equ. / L contains, g / l:, 3; C g 0.43; , 43; , 7. The degree of fluorine regeneration is 24.5%, the degree of iron removal is 90.6%.

Example 2. In 50 ml of the spent solution of the same composition as in example 1, with a temperature of 40 ° C, 2.5 ml con was added with stirring. centered phosphoric acid, which is the stoichiometrically necessary amount by reaction with iron; then treated with 100 ml of acetone with vigorous stirring for 10 minutes and settled for 4 hours. The clarified layer of the solution is drained, and the wet sediment is filtered from the residual mother liquor and dried at 105 C. The humidity of the precipitate is 39%.

5 solutions of acetone are distilled off at t 56-70 ° C. Steppe otgonk 96.5%. Get 48 ml of the regenerate. The composition of the regenerate with an acidity of 0.9 g - eq / l contains, g / l:, 6; C, 9; ,;

0, 4. The degree of fluorine regeneration is 73%, the degree of iron removal is 96.5%.

Example 3.K 50 ml of the spent solution of the same composition as in example 1, with a temperature of 20 ° С

5, while pouring over 3.8 ml of concentrated phosphoric acid, which is 150% of the stoichiometrically required amount in the calculation for iron; then treated with 100 ml of acetone with intensive stirring for 10 minutes. The suspension is settled for 4 hours. The clarified solution is drained, the wet precipitate is filtered off and dried. Sediment humidity 39.1%. Acetone is distilled from the solution, the degree of distillation is 98.2%. 46.8 ml of regenerate is obtained. The composition of the regenerate acidity. 1.15 g-eq / l contains, g / l:, 76; C g 3 2/3; Ni 2.5; Fe 45.2. The degree of regeneration of fluorine is 74.1%, the degree of iron removal is 98.4%. Example 4. 50 ml of the spent solution, of the same composition as in example 1, are treated with temperature with stirring 3.8 ml of co-centric phosphoric acid and 200 ml of acetone. The suspension is settled for 4 hours. The clarified solution is drained, the wet precipitate is filtered off and dried. Sediment humidity 38.8%. Acetone is distilled from the solution. The degree of distillation, acetone 95.1. Receive 47 ml of the regenerate acid with 1.1 k - eq / l of the following composition, g / l: Fe 3 0.56; C, 8; Mi 1.9; ,eight. The degree of fluorine regeneration is 73.8%, the degree of iron removal is 98.8%. Example 5. 50 ml of the treated solution of the same composition as in example 1, with a temperature of 20 ° C, are treated with stirring with 2.3 ml of concentrated phosphoric acid — 90 ml of acetone. The suspension is settled for 4 hours. The clarified solution is drained, the precipitate is filtered off. and dried. Sediment humidity is 39.4%. Acetone is distilled from the solution. The degree of distillation of 96%, get 48.5 ml of regenerate. The composition of the regenerate with an acidity of .81 g - eq / l contains, g / l:, 7; , 0; , 3; p-39.2. The degree of regeneration of fluorine is 66.6%, the degree of iron removal is 94%. Approx. 6. 50 ml of the spent solution of the same composition as in example 1, with temperature. During the mixing, 4 mp of concentrated phosphoric acid and 210 ml of acetone are processed. Suspension defend 4h. The clarified solution is drained, the wet precipitate is filtered off and dried. Sediment humidity 38.6%. Acetone is distilled from the solution. The degree of distillation of 92%. 48.5 g / l of regenerate are obtained. The composition of the regenerate acidity of 1.2 g - eq / l contains, g / l:, 52; , 75; ,eight; , 7. The degree of regeneration of fluorine is 74.2%, the degree of iron removal is 98.8%. The test results are presented in the table.

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The degree of fluorine regeneration during the treatment of the solution with acetone is 24.5%, with the preliminary amount of phosphoric acid being 7374%, the degree of iron removal is 90.6% and 96.5-98.8%, respectively.

The introduction of phosphoric acid in a quantity less than stoichiometrically necessary results in a low degree of fluorine regeneration (1–7%) and an insufficient degree of removal of iron I4%.

The introduction of phosphoric acid in the amount of. stoichiometrically necessary for the formation of iron phosphate, leads to a high degree of regeneration; fluorine and to an increase in the degree of iron removal. The degree of fluorine regeneration is 73%, the degree of iron removal is 96.5%. With a one-and-a-half excess of phosphoric acid, the degree of fluorine regeneration is 74%, the degree of iron deposition is 98.4-98.8%.

With the introduction of phosphoric acid in an amount in excess of 1.5 stoichiometries, the degree of fluorine regeneration increases slightly (up to 74.2%), and the degree of iron removal remains at the same level (i.e. 98.8%). Therefore, the introduction of phosphoric acid in an amount exceeding 1.5 from the stoichiometry is inappropriate.

With the introduction of acetone in the amount of two volumes to one volume of pickling solution, a high degree of regeneration-fluorine reagent is not achieved and the degree of iron removal is sufficient.

In the range of ratios of volumes of acetone and pickling solution 2: 1 4: 1, a significant degree of regeneration of fluorine-reagent (73-74%) is achieved and the degree of iron removal is sufficient (98.4-98.8%).

The addition of acetone in an amount greater than four volumes to one volume of the pickling solution is impractical because it leads to an increase in the energy consumption for the distillation of significant quantities of acetone and slightly affects the degree of fluorine regeneration.

and does not affect the degree of iron removal.

Pretreatment of the pickling solution with phosphoric acid leads to a slight decrease in the degrees of precipitation of chromium and nickel, which is insignificant. Chroma and nickel ions do not have a noticeable effect on the subsequent metal etching process in the regenerated solution, because of its low concentration compared to iron, the etching process is hampered by the accumulation of iron in the etching solution.

According to the proposed method, the degree of iron removal is.

The use of the proposed method makes it possible, using a relatively simple technology, to regenerate expensive fluorine reagent from spent fluorine-containing pickling solutions and return it to the etching cycle.

Thus, as a result of the combined action of phosphoric acid and acetone, it is possible to significantly increase the degree of regeneration of the expensive fluorine reagent, as well as (TO ENHANCE the efficiency of removing iron from the spent pickling solution.

The precipitate of iron phosphate with an admixture of chromium fluoride and nickel can be used in metallurgical production.

Lcetone is easily distilled from the mixture with the solution at low temperatures (56-70 ° C) and reused for the regeneration of α-fluorine. At the same time, losses of acetone are insignificant, they do not exceed 5%. The proposed method is easy to operate, does not require significant costs and provides a high degree of regeneration of the scarce and expensive fluorine reagent.

When treating the pickling solution with acetone, the degree of fluorine regeneration does not exceed 25%. With the introduction of phosphoric acid, followed by treatment of the solution with acetone, the degree of fluorine regeneration reaches 74%.

Claims (1)

METHOD OF REGENERATION FROM WORK- secret fluorine-containing pickling SOLUTIONS, including the introduction of acetone, separation of the precipitate and distillation of acetone, characterized in that, in order to increase the efficiency of the regeneration process, phosphoric acid in the ratio of 1-1.5 to iron is introduced into the solution before acetone is introduced and acetone is introduced in a ratio of 2: 1 - 4: 1 to the volume of the solution.