RU2797807C1 - Packaged adsorbent for sorption of substances from oil-, fat-, oil-contaminated water - Google Patents

Abstract

FIELD: mineral processing.

SUBSTANCE: invention relates to methods for the complex processing of hydro-mineral raw materials, such as natural brines, wastewater, process solutions or associated water from oil fields, with the production of compounds of lithium, rubidium, magnesium, iodine, bromine and other substances. It can be used in oil, chemical, petrochemical, biochemical and other industries. A packaged adsorbent for sorption of substances from oil-, fat-, oil-contaminated water consists of a closed water-permeable package with a finely dispersed adsorbent placed inside it. The package is made of a material whose surface is non-wettable for oil, fat, oil products, and the hydraulic size of the package with the adsorbent is greater than the hydraulic size of the adsorbent particles of the maximum size. The package can be made of a material, the surface of which is non-wettable for oil, fat, oil products after impregnation of the package with water. The package is made of a filter cloth formed by filaments (fibres) wetted by water and having a developed surface or a solid material with a specified porosity and also having a developed surface. The adsorbent particles are selective for lithium ions. The adsorbent particles are based on a chlorine-containing variety of aluminium and lithium double hydroxide.

EFFECT: increased efficiency of adsorption of substances from oil-, grease-, oil-contaminated water by preventing contamination of adsorbent packages and adsorbent particles with oil-, grease-, oil contamination; increasing the adsorption rate due to a decrease in the particle size of the adsorbent with a simultaneous increase in the porosity of the bag material; expanding the range of filtration speed.

11 cl, 6 dwg, 5 ex

Description

The proposed solution relates to methods for the complex processing of hydro-mineral raw materials, for example, natural brines, wastewater, process solutions or associated water from oil fields, with the production of compounds of lithium, rubidium, magnesium, iodine, bromine and other substances. Can be used in oil, chemical, petrochemical, biochemical and other industries.

A method is known for the sorption extraction of lithium from lithium-containing chloride brines (RF patent No. 2688593, IPC C02F 1/28, 2018), in which the original lithium-containing chloride brine is filtered from bottom to top through a layer of granular sorbent based on a chlorine-containing variety of aluminum and lithium double hydroxide ( DHAL-Cl). The disadvantages of this solution are:

• Low brine filtration rate through the granular sorbent bed, which is set to prevent the sorbent granules from being carried away by the brine flow. The low adsorption rate and entrainment of adsorbent particles have a particularly negative effect on the efficiency of the process due to the high cost of the adsorbent. Larger granules are not used, since in this case the working surface area of the adsorbent decreases and the internal diffusion resistance to the adsorption process increases.

• Erosion and destruction of sorbent particles by brine flows and their entrainment by brine flow.

• Contamination of sorbent particles with oil, fat, oil products contained in the brine, which reduces the capacity of the adsorbent.

• High cost of the adsorbent.

The closest to the proposed solution is a method for purifying aqueous solutions (RF patent No. 2640244, IPC C02F 1/28, 2016) by static sorption (with stirring of the solution) on adsorbent powder particles up to 5 mm in size, previously placed in closed permeable bags, made from a track membrane based on polyethylene terephthalate. The disadvantage of the known invention is the low efficiency of the adsorption process.

• Contamination of bags with adsorbent contained in the treated water oil, fat, oil products, which, by blocking the pores in the bag, first hinder, and then completely stop the access of the solution to the adsorbent.

• Low adsorption rate due to the large size (up to 5 mm) of adsorbent particles and (or) low permeability of the bag material, which has a particularly negative effect when the cost of the adsorbent is high.

• Large variation in the hydraulic size (resistance) of the bags with adsorbent, which leads to a decrease in the filtration rate.

The technical result of the proposed solution is to increase the efficiency of the process of adsorption of substances from oil-, fat-, oil-contaminated water due to:

• prevention of pollution of adsorbent packages and particles of adsorbent oil-, fat-, oil pollution:

• increasing the adsorption rate due to a decrease in the size of adsorbent particles with a simultaneous increase in the porosity of the bag material;

• expanding the range of filtration speed.

This technical result is achieved by the fact that in a packaged adsorbent for sorption of substances from oil-, fat-, oil-contaminated water, consisting of a closed water-permeable package with a finely dispersed adsorbent placed inside it, the package is made of a material whose surface is impregnable for oil-, fat- , oil products. The package can be made of a material whose surface is non-wettable for oil, fat, oil products after impregnation of the package with water. The average particle size of the adsorbent does not exceed 2 mm, and the hydraulic size of the package with the adsorbent is greater than the hydraulic size of the adsorbent particles of the maximum size. The porosity of the package material is at least 20%. The package is made of a filter cloth formed by filaments (fibers) wetted by water and having a developed surface or a solid material with a specified porosity and also having a developed surface. The adsorbent particles are selective for lithium ions. The adsorbent particles are made on the basis of a chlorine-containing variety of aluminum and lithium double hydroxide. The package is made with the possibility of regulating its volume and contains a load-weighting agent, and as a load-weighting agent, connectors of the edges of the package or an additional load in the cavity of the package are used. In this case, at least part of the package is made of a transparent material.

The execution of the package from the material, the surface of which is not wetted by oil, fat, oil products, prevents contamination of the adsorbent packages and adsorbent particles and, accordingly. increases the efficiency of the process of adsorption of substances from oil-, fat-, oil-contaminated water. It is possible to achieve non-wetting of the surface of the package with oil, fat, oil products by making a package of woven and non-woven materials, such as cellulose, mixed cellulose ethers, glass fiber (etched to increase the hydrophilization of the surface), etc., the surface of which becomes impregnable for oil, fat -, oil products after its impregnation with water.

To increase the rate of filtration of purified water through the adsorbent layer, the average size of the adsorbent particles should not exceed 2 mm, and the hydraulic size of the bag with the adsorbent should be greater than the hydraulic size of the adsorbent particles of the maximum size. When using mineral or polymeric sorbent granules with sizes greater than 2 mm, the flow rate for fluidizing the bed (the flow is directed from bottom to top) becomes comparable to that for the packaged form. So for various sorbents (granule size 2 mm) with an apparent density of 1.5 to 2.4 g/cm ³ at a flow rate of 25 to 40 m/h (water, 20°C), a complete liquefaction of the layer is observed. When using the packaged form, the soaring of the packages with the sorbent occurs at the same parameters; accordingly, the technological benefit from using the packaged form is lost.

The use of an adsorbent with selectivity towards lithium ions increases the efficiency of the lithium adsorption process. In particular, the adsorbent particles may be based on a chlorine-containing variety of aluminum and lithium double hydroxide.

To ensure that the package is not wetted by oil, fat, oil products, the porosity of the package material must be at least 20%. The execution of the package from the filter cloth, formed by open-pore threads (fibers) or threads (fibers) with a developed surface, provides effective impregnation of the package with water, preventing its contamination with oil, fat, oil products.

The execution of the package with the ability to control its volume (for example, by twisting one of its sides), as well as the addition of a load-weighting agent to the package, allows you to expand the range of filtration speed. As a load-weighting agent, connectors of the edges of the package can be used. For operational visual control of the state of the adsorbent in the package, at least part of the package can be made of a transparent material.

Examples of specific implementation.

An experimental verification of the effectiveness of the proposed solution was carried out on an adsorption unit, which is a vertical transparent cylindrical container (hereinafter referred to as the sorption column - SC) made of polycarbonate (effective height 1000 mm, inner diameter 92 mm), divided by a distribution grid with a lower inlet and upper outlet fittings, and packaged adsorbent placed on the distribution grid.

As a raw material (brine No. 1) for the sorption extraction of lithium, a water-oil emulsion based on crude oil with a density of 0.936 g/cm ³ and an aqueous chloride solution of the following composition was used:

- Na ⁺ - 60 g/l

- K ⁺ - 10 g/l

- Ca ²⁺ - 5 g/l

- Mg ²⁺ - 2 g/l

- Li ⁺ - 40 mg/l

- Petroleum products (NP) - 232 mg/l

An oil-in-water emulsion was obtained by gradually introducing a calculated amount of crude oil into the inlet pipe of a centrifugal circulation pump. The intake and discharge of the pump were connected to a 30-liter tank. During the introduction of oil, it was emulsified, and further the maintenance of the emulsion in a stable state was carried out due to the constant operation of the centrifugal pump. The exact concentration of oil products in the resulting emulsion was determined by fluorimetry (Fluorat 02-5M) with the extraction of oil products from the aqueous phase with hexane.

The water-oil emulsion was fed into the container through the lower fitting. Lithium was adsorbed from brine by bottom-up filtration through a packaged adsorbent.

As the initial solution for the sorption extraction of cesium (brine No. 2), a water-oil emulsion based on crude oil with a density of 0.936 g/cm ³ and an aqueous-salt solution based on metal chlorides of the following composition was used:

- Na+ - 5 g/l

- K+ - 1 g/l

- Ca2+ - 0.5 g/l

- Mg2+ - 0.1 g/l

- Cs+ - 10 mg/l

- NP - 210 mg/l

The cationic composition of brines after its purification from oil products by extraction with hexane was controlled by capillary electrophoresis (Kapel-105M).

The content of oil products in the bags sorbed by the material was also determined by fluorimetry with preliminary drying at room temperature to constant weight and subsequent extraction of NP with hexane.

The studies are illustrated by graphs, where in Fig. 1 shows the results for example 1; in fig. 2 - results for example 2; in fig. 3 - results for example 3 (without weighting agent); in fig. 4 - for example 3 (with a weighting agent); in fig. 5 - results for example 4; in fig. 6 - results for example 5.

Example 1

Granular adsorbent based on DHAL-Cl (a chlorine-containing variety of double aluminum and lithium hydroxide) fraction 0.1-0.3 mm was placed in 2 g flat round bags of two discs sewn along the edges with a diameter of 30 mm made of cotton fabric. Two types of packages were chosen with a pore size of 50 μm, but different porosity - 15% and 40% (according to the gas pycnometry method). Also, a glass ball with a diameter of 8 mm was placed in the package as a weight.

In the first test, the SC was filled with 100 bags with a porosity of 15%, which corresponds to 200 g of the sorbent. In the second test, packages with a porosity of 40% were used.

A water-oil emulsion (brine No. 1) was passed through the SC along a closed circuit with a linear velocity in the column equal to 32 m/h, which corresponded to the mode of intensive mixing of the packages inside the filter. The total brine volume was 20 L, corresponding to a total lithium content of 800 mg. The temperature of the brine was 20°C. At certain intervals from the beginning of filtration (10, 20, 30, 60, 90, 120, 180 min), water samples (1 ml each) were taken to control the cationic composition and evaluate the sorption rate. Based on the data obtained, an isotherm of the change in the lithium concentration in the brine versus the time of sorption was plotted (Fig. 1).

At the end of the experiment, the mass fraction of oil products in the package material was determined. To do this, after washing the SC with pure brine, the packages were taken out, dried in air to a constant weight, and the OP was extracted with hexane, followed by determination of the concentration and recalculation for the content of OP in the material of the packages.

The mass content of OP in CB filters with a porosity of 15% was 3.7%. Taking into account the difference in the true density of cellulose and oil products, the pore volume occupied by oil products can be estimated at approximately 30%. The mass content of OP in CB filters with a porosity of 40% was 5.1%. Accordingly, the pore volume occupied by oil products for this material is already 12%. The cumulative effect of oil contamination of the membrane of the filter material on the mass transfer between the internal volume of the package and the external liquid medium is clearly visible on the lithium sorption isotherms: less porosity - slower sorption rate.

Example 2

Granular adsorbent based on porous nickel hexacyanoferrate fraction 0.1-0.3 mm in the amount of 5 g was placed in a cylindrical bag of filter glass cloth. The glass cloth was preliminarily etched in a mixture of hydrofluoric and sulfuric acids to increase the surface roughness of the glass fibers. The resulting porosity of the material was 55% (according to the gas pycnometry method). Cylindrical package parameters: length - 40 mm, diameter 20 mm, fiberglass thickness 1 mm. The ends are compressed and connected by a molten polymer. Also, a glass ball with a diameter of 10 mm was placed in the package as a weight.

The SC was filled with 40 bags of adsorbent, which corresponds to 200 g of sorbent. Brine No. 2 was passed through the SC in a closed loop with a linear velocity in the column equal to 57 m/h, which corresponded to the regime of intensive mixing of the packages inside the filter. The total brine volume was also 20 liters, which corresponds to a total cesium content of 200 mg. The temperature of the brine was 20°C. At certain intervals from the beginning of filtration (10, 20, 30, 60, 90, 120, 180 min), water samples (1 ml each) were taken to control the cationic composition and evaluate the sorption rate (Fig. 2).

The content of NPs in the filter material made of treated glass cloth is minimal among all the studied materials and is 0.2% due to the pronounced oleophobicity of the surface after etching with hydrofluoric acid.

Example 3

A granulated selective sorbent for the extraction of heavy metals based on a strongly acidic cation exchanger KU-2x8-GO modified with tin (IV) hydroxide 0.5-1.0 mm in an amount of 5 g was placed in a cylindrical bag of filter glass cloth. The glass cloth was preliminarily etched in a mixture of hydrofluoric and sulfuric acids to increase the surface roughness of the glass fibers. The resulting porosity of the material was 50% (according to the gas pycnometry method). Cylindrical package parameters: length - 40 mm, diameter 20 mm, fiberglass thickness 1 mm. The ends are compressed and connected by a molten polymer (polyethylene). Two types of bags of 40 pieces were made: with a weighting agent in the form of a glass ball (10 mm) and without.

Testing packages without weighting agent.

The SC was filled with 40 bags of adsorbent, which corresponds to 200 g of sorbent. A solution (chloride) of the following composition was passed through the SC along a closed circuit:

- Na+ - 100 mg/l

- K+ - 10 mg/l

- Ca2+ - 40 mg/l

- Mg2+ - 5 mg/l

- Cu2+ - 50 mg/l

- Pb2+ - 10 mg/l

NP - 100 mg/l

with a linear velocity in the column equal to 18 m/h, at which the rise and hovering of the packages with the sorbent in the volume of the column were observed. The total volume of the solution was 20 liters, which corresponds to a total copper content of 1000 mg and lead of 200 mg. The temperature of the brine was 20°C. At certain intervals from the beginning of filtration (10, 20, 30, 60, 90, 120, 180 min), water samples (1 ml each) were taken to control the content of copper and lead and evaluate the sorption rate (Fig. 3).

Weight pack testing.

The SC was filled with 40 bags of adsorbent, which corresponds to 200 g of sorbent. A solution of the same composition was passed through the SC along a closed circuit with a linear velocity in the column equal to 55 m/h, at which the packages with the sorbent were lifted and hovered in the volume of the column. The total volume of the solution was 20 liters, which corresponds to a total copper content of 1000 mg and lead of 200 mg. The temperature of the brine was 20°C. At certain intervals from the beginning of filtration (10, 20, 30, 60, 90, 120, 180 min), water samples (1 ml each) were taken to control the content of copper and lead and evaluate the sorption rate (Fig. 4).

In the general case, the sorption rate will be determined either by the rate of diffusion (mass transfer) between the external brine and the internal volume of the package, or between the internal volume of the package and diffusion into the granules (particles) of the sorbent. In this example, a strongly acidic sorbent KU-2x8-GO was used, which has a high sorption rate, so the limiting stage of sorption is the mass exchange between the internal volume of the package and the solution outside, since with an increase in the flow rate, a significant increase in the sorption rate of copper and lead is observed. Accordingly, for sorbents with a high sorption rate (high specific surface area, small particle size), it is advisable to use bagging with a weighting agent to increase the operating flow rate without removing bags with sorbent from the filter volume.

Example 4

Granular adsorbent based on DHAL-Cl fraction 0.1-0.3 mm in the amount of 1 g was placed in two types of bags.

- packages 2.2×2.5(×0.3) cm, material - track membrane made of lavsan 75 µm thick with a pore size of 0.1 µm (material and dimensions are similar to packages from RF patent No. 2640244). The porosity of the material is 10-12% (according to the gas pycnometry method).

- packages 2.2 × 2.5 ( × 0.3) cm, material - filter glass cloth treated with a mixture of acids as in example 2.

In the first test, the SC was filled with 100 lavsan bags with an adsorbent, which corresponds to 100 g of the sorbent. In the second test, glass fiber bags were used. Brine was passed through the SC in a closed loop at a linear velocity in the column equal to 32 m/h, which corresponded to the mode of intensive mixing of the packages inside the filter. The total brine volume was 10 L, corresponding to a total lithium content of 400 mg. The temperature of the brine was 20°C. At certain intervals from the beginning of filtration (10, 20, 30, 60, 90, 120, 180 min), water samples (1 ml each) were taken to control the cationic composition and evaluate the sorption rate. Based on the data obtained, isotherms of changes in the lithium concentration in the brine versus the time of sorption were plotted (Fig. 5).

The content of NP in the material of the packages after sorption:

- lavsan - 3.9%

- fiberglass - 0.25%.

Insignificant mass transfer when using lavsan bags is more associated with the smallest pore size among all materials with relatively low porosity. In addition to this, the lavsan surface was visually covered with a thin film of petroleum products at the end of the experiment.

Example 5

Granular adsorbent based on DHAL-Cl fraction 0.1-0.3 mm in the amount of 5 g was placed in a cylindrical bag of cotton fabric (similar to example 1) with a pore size of 50 μm and a total porosity of 40%. Parameters of a cylindrical package: length - 40 mm, diameter 20 mm. The end face on one side is compressed into a cone and fixed with a copper wire with a varnish coating with a diameter of 2 mm and a mass of 5 g (as a weighting agent). In five packages, a transparent disk made of polyethylene terephthalate (PET) was glued into the opposite end of the cylinder for visual control of the state of the sorbent.

The SC was filled with 40 bags of adsorbent, which corresponds to 200 g of sorbent. Brine No. 1 was passed through the SC in a closed loop with a linear velocity in the column equal to 70 m/h, which corresponded to the regime of intensive mixing of the packages inside the filter. The total brine volume was also 20 L, corresponding to a total lithium content of 800 mg. The temperature of the brine was 20°C. At certain intervals from the beginning of filtration (10, 20, 30, 60, 90, 120, 180 min), water samples (1 ml each) were taken to control the cationic composition and evaluate the sorption rate (Fig. 6).

The content of oil products in the bag material after the sorption cycle was 6.8%, which is most likely due to the presence of PET elements that have oleophilic properties and are well wetted by oil products under experimental conditions.

The conducted studies show that the application of the proposed solution increases the efficiency of the process of adsorption of substances from oil-, grease-, oil-contaminated water by preventing contamination of the adsorbent packages and adsorbent particles, increasing the adsorption rate and expanding the filtration rate range.

Studies have shown that with an increase in the particle size of the adsorbent, its hydraulic fineness also increases, but at the same time, the sorption rate decreases due to the weakening of the diffusion of the target components into the granules. Therefore, when using sorbent granules larger than 2 mm in combination with the "protective" material of the bags, the rate of extraction of the target components from the solution decreases sharply.

Claims (11)

1. A packaged adsorbent for sorption of substances from oil, fat, oil-contaminated water, consisting of a closed permeable package with a fine adsorbent placed inside it, characterized in that the package is made of a material whose surface is impregnable for oil, fat, oil products , and the hydraulic fineness of the bag with the adsorbent is greater than the hydraulic fineness of the adsorbent particles of the maximum size. 2. The packaged adsorbent according to claim 1, characterized in that the package is made of a material whose surface is impregnable for oil, fat, oil products after impregnation of the package with water. 3. Packaged adsorbent according to claim 1, characterized in that the average particle size of the adsorbent does not exceed 2 mm. 4. Packaged adsorbent according to claim 1, characterized in that the porosity of the package material is at least 20%. 5. A packaged adsorbent according to claim 4, characterized in that the package is made of a filter cloth formed by porous filaments or filaments with a developed surface. 6. The packaged adsorbent according to claim 1, characterized in that the adsorbent particles have selectivity with respect to lithium ions. 7. The packaged adsorbent according to claim 6, characterized in that the adsorbent particles are based on a chlorine-containing variety of aluminum and lithium double hydroxide. 8. Packaged adsorbent according to claim. 1, characterized in that the package is made with the ability to control its volume. 9. Packaged adsorbent according to claim 1, characterized in that the package contains a load-weighting agent. 10. Packaged adsorbent according to claim 1, characterized in that connectors of the edges of the package are used as a load-weighting agent. 11. The packaged adsorbent according to claim 1, characterized in that at least part of the package is made of a transparent material.

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