RU2481409C1 - Extraction of copper from aqueous solutions using plant oils - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of extracting copper from an aqueous solution involves bringing an extractant in form of plant oil into contact with the solution. The mixture is stirred, settled and subjected to phase separation. Extraction is carried out from an aqueous solution with copper concentration ≤5 g/dm³ with ratio of the aqueous phase to the organic phase A:O≤8, pH 5.5-6.5 and 8.5-10.5, wherein pH is controlled for not more than 30 minutes.

EFFECT: high efficiency of extracting copper from aqueous solutions with simultaneous cost-effectiveness and safety of the process.

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Description

The method of extraction of copper from aqueous solutions relates to the field of extraction of substances with organic extractants from aqueous solutions and can be used in non-ferrous and ferrous metallurgy, as well as for the treatment of industrial and domestic wastes.

Known methods for the extraction of copper by extraction with a mixture of unsaturated carboxylic acids of the composition, wt.%: 20-30 oleic, 20-40 linoleic, 40 erucic and 2-9 palmitic in the range of pH = 4-8 [Bubnov V.K. and others. Theory and practice of mining for combined leaching methods. Alma-Ata, 1992, p. 522].

The disadvantage of this method is the relative high cost of the extractants used.

The closest technical solution is the extraction of copper from aqueous solutions with a concentration of 500 mg / DM ³ vegetable oils at pH≥4, the ratio of organic and aqueous phases O: B = 1: 19 and regulation of the pH for no more than 4.5 [RF Patent No. 2155815 from 2000, IPC 7 С22В 3/26 // С22В 3/26 // С22 В 3/26 // С22В 15:00, BI No. 25].

The disadvantage of this method is the insufficient accuracy of the extraction conditions. It is known that at pH> 5.5, copper hydroxide is released from the aqueous solution. In addition, extraction from more concentrated aqueous solutions> 500 mg / dm ³ , other O: B ratios and extraction time was not studied, only 4 types of vegetable oils were studied for extraction.

The objective of the invention is to clarify the optimal parameters for the extraction of copper ions from aqueous solutions with vegetable oils (initial concentration, pH, the ratio of organic and aqueous phases O: B, time and temperature) using more types of vegetable oils.

The technical result that can be achieved by carrying out the invention consists in a high degree of efficiency of copper extraction from aqueous solutions with simultaneous economical and safe process.

This technical result is achieved by the fact that in the known method for extracting copper from an aqueous solution with vegetable oils, including contacting the extractant and the solution, mixing the mixture, settling and phase separation, the extraction is carried out from an aqueous solution with a concentration of ≤5 g / dm ³ for copper at B: O≤8, pH 5.5-6.5 and 8.5-10.5 and adjusting the pH for no more than 30 minutes.

The essence of the method is illustrated by the data of figures 1-6, which indicate the concentration of copper in the initial solutions, the extraction time at a given pH value, the copper concentration and pH in the clarified aqueous phase, the distribution coefficient, calculated as the ratio of the equilibrium copper concentrations in the organic and aqueous phases .

Stirring and maintaining the desired pH value was carried out until in the future, the acid-base characteristics of the system changed slightly. However, for a greater guarantee of achieving equilibrium, the contact of the organic and aqueous phases was carried out for at least a day. Upon reaching equilibrium between the organic and clarified aqueous phases, the organic phase was separated from the aqueous phase; in the latter, the pH value and residual copper concentration were determined. To maintain a given pH value of the solution during the extraction, alkali or acid solutions were used as neutralizers.

Using the values of the concentrations of copper in the aqueous solution, the initial one and after extraction, the distribution coefficient of copper between the organic and aqueous phases was calculated.

Examples of specific performance of the method.

Example 1 (FIG. 1)

Figure 1 shows the dependence of the residual concentration of copper ions on the pH of the solution. The extractant is olive oil, C ₀ = 1.2 g / dm ³ , the extraction time is 1 hour, O: B = 1: 3, t = 24 ° C. The best extraction results were obtained at pH 5.5-6.5 and 8.5-10.5. Probably, copper complexes of various compositions with extractant components are extracted: one at pH 6, the other at pH 10. Precipitation forms at pH≥11.

Example 2 (figure 2)

Figure 2 shows the dependence of the residual concentration of copper ions on the extraction time. The extractant is olive oil. C ₀ = 3.21 g / dm ³ , pH 10, O: B = 1: 3, t = 24 ° C. It can be seen that the extraction time does not exceed 30 minutes

Example 3 (figure 3)

Figure 3 shows the dependence of the residual concentration of copper ions on the ratio B: O and extraction pH: graphs 1 — pH 6 and 2 — pH 10. Extractant — olive oil, C ₀ = 1.1 g / dm ³ , extraction time — day , t = 24 ° C. Extraction is carried out at B: O≤8. When B: O> 8 precipitation is formed.

Example 4 (figure 4)

Figure 4 shows the dependence of the residual concentration of copper ions on time and the initial concentration With ₀ , g / DM ³ : 1,1; 2.2; 3.2; 4,5. The extractant is olive oil, pH 10, O: B = 1: 3, t = 24 ° C. Extraction is carried out in a time not exceeding 30 minutes.

It was found that extraction is described by a first order equation of the form

where K is the rate constant of the process.

According to figure 4 calculated values of K in equation (I):

In the range of initial concentrations With ₀ = 1-3 g / DM ³ with increasing concentration, the speed of the process increases.

Example 5 (FIG. 5)

Figure 5 shows the dependence of the residual concentration of copper ions on the extraction time and temperature t = 18, 24, 30, 35 ° C. The extractant is olive oil, pH 10, C ₀ = 4.5 g / dm ³ , O: B = 1: 3. Extraction is carried out in a time not exceeding 30 minutes.

It has been established that extraction is described by a first order equation (1). According to figure 5 calculated values of K in equation (1):

In the temperature range t = 18-35 ° C, the speed of the process decreases.

Based on the kinetic analysis of the reaction, it can be assumed that the first order of the process — an increase in the rate of the process with an increase in the initial concentration — may indicate that the process is limited by the rate of external diffusion. A decrease in the extraction rate with increasing temperature may be due to coalescence (coalescence of drops of vegetable oil) inside the mobile solution with stirring. With increasing temperature, the coalescence rate increases, and therefore, the interfacial surface between the organic and aqueous phases decreases, which, according to Fick's first law, reduces the diffusion rate. In addition, the position of the double bond in oleic acid can change when heated and under various chemical influences. For example, heat treatment in an alkaline medium promotes the migration of a double bond to a position adjacent to the carboxyl group.

Example 6 (Fig.6)

Figure 6 shows the dependence of the distribution coefficient D on the type of vegetable oil: 1 - apricot, 2 - pumpkin, 3 - cedar, 4 - soybean, 5 - grape, 6 - corn, 7 - walnut, 8 - sunflower, 9 - linseed 10 - olive. O: B = 1: 6. t = 24 ° C.

Extraction conditions:

a - C ₀ = 1.1 g / dm ³ ; pH = 6 b - C ₀ = 1.1 g / dm ³ ; pH = 10

in - With ₀ = 5 g / DM ³ ; pH = 6 g - C ₀ = 5 g / dm ³ ; pH = 10

For apricot cedar, soybean and corn oils under extraction conditions “g”, when hydroxides precipitated upon neutralization to pH 10, neutralization with sulfuric acid was carried out, which was added portionwise until the hydroxides were dissolved (almost to pH 6.5).

High extraction rates were obtained for apricot, pumpkin, soy, walnut, sunflower and olive oils; grape and linseed oil are poorly extracted from copper ions.

High extraction rates were obtained, probably because vegetable oils contain oleic acid and other components that can extract heavy metal ions. Vegetable oils are saturated and unsaturated (with one, two and three double bonds) monobasic fatty acids with an unbranched carbon chain and an even number of carbon atoms (mainly C ₁₆ and C ₁₈ ). So, the content of oleic acid, wt.%: In sunflower oil 24-40, in corn oil - 30-49, in olive oil - about 80, in soybean oil - 23-29. In addition, fatty acids with an odd number of carbon atoms (from C ₁₅ to C ₂₃ ) were found in vegetable oils in small amounts.

Claims (1)

A method of extracting copper from an aqueous solution with vegetable oils, including contacting the extractant and the solution, mixing the mixture, settling and phase separation, characterized in that the extraction is carried out from an aqueous solution with a copper concentration of ≤5 g / dm ³ with the ratio of the aqueous and organic phases B: O ≤8, pH 5.5-6.5 and 8.5-10.5 and adjusting the pH for no more than 30 minutes.

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