RU2110480C1 - Method for purification of technological solutions and sewage against organic materials - Google Patents

Abstract

FIELD: purification of technological solutions and sewage against organic materials which takes place with the help of adsorbents. SUBSTANCE: technological solutions and sewage obtained by hydrometallurgical production of heavy nonferrous metals are purified against organic materials, porous synthetic carbon material being used as adsorbent. Proposed adsorbent may be regenerated by various means. Proposed carbon material represents carbon black being covered with carbon layer having thickness in 100-10000

. Radius of curve of the layer is 100-10000

, its actual density is 1.8-2.1 g/cm³, its X-ray density being 2.112-2.236 g/cm³. EFFECT: improved efficiency of the method. 2 cl, 2 dwg, 4 tbl

Description

 The invention relates to hydrometallurgy of heavy non-ferrous metals in terms of the use of liquid extraction processes for the extraction of metals and can be used in other areas of metallurgy, chemical industry, utilities and other industries related to the problem of cleaning aqueous solutions from organic contaminants.

 The use of organic reagents for the extraction of metals from aqueous solutions is associated with pollution of the aqueous phase with organic impurities, which determines the environmental hazard of extraction production and is a factor in the cost of metal production due to loss of reagents.

 Therefore, the development of extraction technologies is inextricably linked with the prevention of environmental pollution by technological solutions, extractants, modifiers, diluents [1]. For this, on the one hand, organic reagents less soluble in the aqueous medium are used; on the other hand, methods for purifying aqueous solutions of organic impurities are being improved. Physicochemical methods for trapping organic substances, such as coalescence, coagulation, flotation and coprecipitation, are widely used [2].

 The most effective method of purification of aqueous solutions from organic impurities is sorption on porous materials. A large number of such materials are known, among which carbon adsorbents — activated carbons — stand out [3]. As noted in the review [1], processes using active carbons in the adsorption – desorption – regeneration cycles require an additional stage — the stage of periodic reactivation of activated carbon. This need arises due to a drop in the sorption capacity of coal and leads to a significant increase in the cost of the entire sorption purification process. The complexity and high cost of regeneration and reactivation processes led to attempts to use powdered carbon sorbents without their regeneration [4]. Such adsorbents, after a single adsorption, are burned as fuel, which leads to both the loss of the sorbent and trapped organic compounds, among which are expensive reagents.

 The granular carbon materials used for sorption wastewater treatment should have not only acceptable sorption properties, but also high operational characteristics, such as mechanical strength, thermal stability, ease of desorption of organic impurities.

 In domestic practice, the use of batch processes, including the regeneration stage for cleaning solutions of hydrometallurgical production, is not widely used, largely due to the lack of carbon adsorbents with the necessary properties. Known work on the purification of raffinates from petroleum sulfoxides using active carbons BAU and AG-3 [5], however, the issues of regeneration and the cyclic mode of operation of adsorbents are practically not developed.

 A known method of purification of raffinates of the hydrometallurgical production of copper, nickel, uranium [6] using activated carbon Filtrasorb company "Atlas" (USA), followed by regeneration of the sorbent with superheated water vapor.

The closest technical solution adopted for the prototype is a method of adsorption purification of solutions from organic impurities on activated carbon [7]. Wastewater containing volatile phenols was subjected to purification. The regeneration of the adsorbent was carried out in two stages: the isolation of the adsorbed phenols with an alkali solution and reactivation by evacuation at 150 - 500 ^o C, followed by treatment with a gas-vapor mixture at 800 ^o C. This regeneration method is typical for activated carbons. Moreover, as noted in [7], the final stage of the reactivation process is accompanied by the appearance (due to burning, the degree of which is 25%) of carbon, which does not have sorption properties and an increase in the ash content of the adsorbent.

 As noted in [1], the proportion of activated carbon lost during thermal regeneration, including high-temperature reactivation, can reach 30% in one cycle, and softening the parameters of the carbon adsorbent regeneration process (lowering temperature, decreasing time) reduces adsorbent losses and the cost of the entire sorption process cleaning up.

 The invention solves the problem of improving the efficiency of wastewater and process solutions from organic contamination by the sorption method with multiple operation of the adsorbent in the adsorption-regeneration mode.

при радиусе кривизны слоя 100-10000

; истинная плотность носителя составляет 1,8 - 2,1 г/см³, рентгеновская плотность 2,112 - 2,236 г/см³, распределение пор в слое углерода по размерам с одним или двумя максимумами: в области 40-2000

[8]. Регенерация адсорбента проводится перегретым водяным паром при 120-200^oC или термически, потоком воздуха при 100-500^oC. Структура носителя обуславливает высокую механическую прочность (до 300 кг/см³), термическую устойчивость и химическую инертность.The problem is solved in that carbon material is used as an adsorbent (called Sibunit, containing carbon black coated with a layer of pyrocarbon having a pore volume of 0.2 - 1.7 g / cm ³ and a carbon layer thickness of 100 - 10000

when the radius of curvature of the layer is 100-10000

; the true density of the carrier is 1.8 - 2.1 g / cm ³ , x-ray density of 2.112 - 2.236 g / cm ³ , the pore size distribution in the carbon layer with one or two maxima: in the region of 40-2000

[eight]. The adsorbent is regenerated by superheated water vapor at 120-200 ^o C or thermally, by air flow at 100-500 ^o C. The structure of the carrier determines high mechanical strength (up to 300 kg / cm ³ ), thermal stability and chemical inertness.

 A feature of this carbon material in comparison with active carbons is its structure: the granule frame is composed of graphite crystallite chains, which form an ordered rigid structure similar to the structure of polymer chains in synthetic resins. The texture of the sibunite material is mainly represented by meso- and macropores with a small specific micropore volume. In traditional sorbents, such as activated carbons, an increase in the proportion of micropores leads to an increase in the sorption capacity of the sorbent. However, the proposed material in terms of sorption capacity is not inferior to charcoal (having a microporous structure), and in its ability to regenerate significantly surpasses them, which significantly reduces the cost of adsorption purification processes using the sorption-regeneration cycle.

Samples of the carbon carrier are black spherical granules with a size of 0.5 - 4.0 mm, consisting of 99% carbon [8]. The specific surface of the material reaches 600 m ³ / g (according to phenol) with a bulk density of 0.4 - 0.6 g / cm ³ .

 In the work we used samples of sibunite with the characteristics given in table. one.

 The effectiveness of the proposed material in the processes of sorption purification from organic contaminants is demonstrated in the following examples.

 Example 1. Demonstrates the kinetic characteristics of the sorption of organic compounds by the proposed carbon sorbent in comparison with activated carbon.

In a glass beaker with a stirrer with a capacity of 0.3 dm ^3, 0.2 dm ^{3 of an} aqueous solution (120 mg / dm ³ ) of trioctylammonium carbonate (TOMAK), which is often used as an anion exchange extractant, is placed. 1 g of carbon adsorbent S1 is added to the glass with stirring and the residual TOMAK concentration is measured depending on the phase contact time. For the control experiment, BAU-B activated carbon (1 g) was used as a sorbent. The results of measuring the residual concentration are shown in FIG. 1.

 From FIG. 1 it follows that in order to achieve sorption equilibrium, the S1 sorbent takes approximately 0.5 hours (curve 1), which is half as much as for BAU-B coal (curve 2). Thus, the proposed carbon sorbent is superior in kinetic characteristics to activated carbon, which in practice means the possibility of increasing the productivity of sorption equipment by reducing the phase contact time.

 Example 2. Demonstrates a higher thermal stability compared to activated carbon of the proposed carbon adsorbent and the possibility of thermal removal of sorbed organic compounds from it.

Samples of the carbon material S2, which is initial and saturated in the aqueous phase with synthetic fatty acids (C ₇ -C ₉ fraction) of carbon material, are heated in air and a change in their weight is recorded using a Paulik-Hervey derivatograph. For comparison, the same derivatograms were obtained for DAC activated carbon.

 The measurement results are presented in FIG. 2.

The curves show that at temperatures above 500 ^o C the sample of sorbent S2, saturated with organic matter, shows the dependence of weight loss on temperature (curve 2), similar to the dependence of the original sample (line 1). Weight changes up to 500 ^o C (curve 2) due to the removal of sorbed organics and is evidence of the possibility of thermal regeneration of the sorbent. Since the weight loss of the initial sorbent is invisible to 500 ^o C, but observed at higher temperatures, the temperature range of desorption of organic compounds in an oxidizing atmosphere should not exceed this value. Curve 3 shows the change in the weight of the active carbon DAC. It is seen that the intensive destruction of the sorbent begins at temperatures below 200 ^o C, which makes the process of thermal regeneration of coal in an atmosphere of air unsuitable. Note that at a temperature of 500 ^o C there was a complete destruction of activated carbon.

 Example 3. Demonstrates the advantages of the proposed sorbent during its operation in cyclic (sorption-regeneration) mode of operation.

The object of sorption purification is a cobalt electrolyte containing 40 g / dm ³ CoSO ₄ and 0.3 - 0.5 g / dm ³ synthetic fatty acids, which are used as a diluent in the process of extraction purification of electrolyte from nickel. The adsorbent cycle consists of the processes of sorption of organic impurities and regeneration of the adsorbent.

Sorption is carried out under static conditions similar to those described in example 1. The phase contact time was 1 hour. As an object of comparison, DAC activated carbon is used. The regeneration of sorbents saturated with organic matter is carried out with superheated steam at a temperature of 125 - 130 ^o C.

 In the table. Figure 2 shows the exchange capacity of the carbon sorbent S3 and activated carbon in ten consecutive sorption - regeneration cycles.

 From the above data it follows that the sorption characteristics of the proposed material practically do not change during 10 cycles of adsorption - regeneration, while the sorption capacity of active carbon DAC is significantly reduced.

 Example 4. Demonstrates the effectiveness of the carbon sorbent treatment of wastewater from the hydrometallurgical production of tungsten from organic contaminants - trialkylamine (TAA) and isooctanol (IO) under dynamic conditions.

Wastewaters of the current tungsten production are subjected to purification, containing 15–40 mg / dm ³ TAA, 50–100 mg / dm ³ IO, 40–60 g / dm ³ sodium chloride, pH 7.0. An adsorber with a fixed layer of carbon material S4 with a volume of 6 dm ³ and a ratio of height: diameter of 8: 1 is used. The feed rate of the pores to be cleaned is 2 to 3 specific volumes per hour. The content of organic impurities is measured at the inlet and outlet of the adsorber. The performance of the adsorbent S4 are presented in table. 3.

From the data table. 3 it follows that the “slip” of organic contaminants is due to the presence of an ionic discharge at the adsorber outlet in the range of 560–600 specific volumes. To the desired degree of wastewater treatment (95% of AI and 97% by TAA) adsorbent S4 of 6 dm ³ of purified 3,5 m ³ wastewater.

To regenerate the adsorbent, superheated steam under a pressure of 3 ATM is used (regeneration temperature 120 - 130 ^o C), the total flow rate of which was 15 kg / kg of sibunit. In this case, organic substances are released into the condensate as a separate phase and were suitable for reuse. After regeneration of the adsorbent, its sorption characteristics were completely restored.

 Example 5. Demonstrates the possibility of regeneration of the proposed adsorbent in various ways.

 Adsorbent S2 is preliminarily saturated with organic compounds (quaternary ammonium salts and oleic acid) so that their sample content is 15 wt.%, After which the regeneration process is carried out chemically or thermally. The chemical method of regeneration consists in washing the sorbent with organic solvents at elevated temperature, and the thermal method in calcining in air. In the table. 4 shows the conditions and degree of regeneration of the sorbent, as well as its loss. The degree of regeneration in the case of chemical regeneration is determined by the loss in weight of the sample. For the thermal regeneration method, the degree of regeneration was 100%, and weight loss is caused not only by the removal of sorbed organic compounds, but also by the combustion of part of the adsorbent.

 Tab. 4 shows the possibility of varying the methods and parameters of the regeneration process of the sibunite adsorbent over a wide range.

 Example 6. Demonstrates the choice of the temperature range of regeneration of the proposed adsorbent with superheated water vapor.

A sample of adsorbent S1 is used to purify cobalt electrolyte from synthetic fatty acids (FFA) under dynamic conditions during operation in the adsorption-regeneration cycles. Sorption is carried out in an adsorber with a fixed adsorbent layer with a volume of 3 dm ³ . The transmission rate of solutions is 2.5 specific volumes per hour. After saturation of the adsorbent, defined as a “breakthrough” of organic compounds, the sorbent layer is purged with superheated steam and the amount of desorbed organic compounds in the condensate is determined. The quantity of organic compounds desorbed from 1 dm ^{3 of the} sorbent is taken as the exchange capacity of the adsorbent. In all cases, the regeneration time was 0.5-1.5 hours, while the moment of completion of the regeneration is determined by reaching the content of FFA in the condensate of less than 0.2 g / cm ³ . The regeneration temperature is controlled by changing the pressure of the supplied steam, and a superheater is used to reach temperatures above 150 ^o C. The data obtained exchange capacity are given in table. 5.

The data table. 5 show that the most effective regeneration of the proposed sorbent with water vapor occurs at temperatures of 120 -200 ^o C. The decrease in the exchange capacity at temperatures above 200 ^o C is associated with the decomposition of organic compounds. It should be noted that a wide range of organic compounds used in hydrometallurgy, by their properties (boiling point, thermal stability) is close to FFA, therefore, the selected sorbent regeneration interval by superheated steam (120 - 200 ^o C) can be used to regenerate other reagents (extractants , modifiers, thinners).

 Thus, as shown in the examples, the proposed material has demonstrated high efficiency in the processes of sorption purification of solutions of hydrometallurgical plants from organic compounds. The use of material instead of activated carbons can reduce the consumption of reagents, energy resources during the regeneration of the sorbent, return organic matter for reuse, which leads to increased economic indicators of the entire hydrometallurgical production.

 Sources of information.

 1. Grebenkin S.A., Meretukov M.A. Decrease in losses of solvents in the conditions of extraction production of non-ferrous metallurgy. Review TsNIIEITSM, ser. Production of heavy non-ferrous metals., M. 1985, issue 5.

 2. Koganovsky A. M., Klimenko N. A., Levchenko T. M., Marutovsky R. M., Roda I. G. Wastewater treatment and use in industrial water supply. M.: Chemistry, 1983, 288 p.

 3. Smirnov A.D. Sorption water purification. L .: Chemistry, 1982, 168 p.

 4. Podlesnyuk V.V., Klimenko V.A. Extraction methods for the regeneration of adsorbents. -Chemistry and technology of water., 1988, v. 10, N4, p. 303-311.

 5. Vax G. L., Kozhemyakin V.A., Yesenina I.V., Toronatskaya N.P. Wastewater treatment from petroleum sulfoxides. Non-ferrous metals., 1985, N 5, p. 70-72.

 6. Ritchie G.M., Ashbrook A.V. Extraction. Principles and application in metallurgy. M .: Metallurgy, 1983, 407 p.

 7. Kazakov V.A., Surinova S.I. The reaction of carbon sorbents after wastewater treatment. -Coke and Chemistry., 1982, N 4, p. 49.

 8. US patent N 4978649, MKI C 01 B 31/10, 1990.

Claims (1)

1. The method of purification of technological solutions and wastewater from organic substances, including adsorption on a porous carbon material with subsequent regeneration, characterized in that the adsorbent is a carbon material with a pore volume of 0.2 - 1.7 cm ³ / g, containing carbon black coated with a layer of carbon with a thickness of 100 - 10,000

when the radius of curvature of the layer is 100 - 10000

true density of 1.8 - 2.1 g / cm ³ , x-ray density of 2.112 - 2.236 g / cm ³ and pore size distribution in the carbon layer with one or two maxima in the region of 40 - 2000

2. The method according to p. 1, characterized in that the regeneration of the adsorbent is carried out with superheated steam at 120 - 200 ^o C or thermally heated to 500 ^o C.

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