Composite filter material and oil removal method for removing oil from extraction system

Abstract

This invention provides a composite filter media and oil removal method for removing oil from an extraction system. The composite filter media comprises a layered quartz sand filter layer and an activated carbon filter layer, with the activated carbon filter layer located at the bottom of the quartz sand filter layer. The volume ratio of the quartz sand filter layer to the activated carbon filter layer is (1-3):1. The quartz sand filter layer contains quartz sand material with a SiO2 content ≥98wt%. The activated carbon filter layer contains activated carbon material with an iodine value ≥800mg / g. This invention's composite filter media, by employing a layered structure of upper quartz sand and lower activated carbon, and by controlling the filter layer volume ratio, the SiO2 content in the quartz sand material, and the iodine value of the activated carbon material, achieves graded interception and deep adsorption of floating oil, emulsified oil, and dissolved oil in the extraction system.

Description

Technical Field

[0001] This invention belongs to the field of extraction process wastewater treatment technology, and relates to a composite filter material and oil removal method for removing oil from extraction systems. Background Technology

[0002] In the field of hydrometallurgy, extraction is a core step in the separation and purification of valuable metals, widely used in the extraction of key metals such as lithium, nickel, and cobalt, and particularly suitable for mainstream processes such as the recycling of waste ternary batteries and the processing of laterite nickel ore. During extraction, the organic phase (extractant, diluent, etc.) comes into full contact with the aqueous phase (lithium sulfate solution, nickel-cobalt leaching solution, etc.), which easily leads to emulsification and entrainment, resulting in a large amount of organic oil remaining in the raffinate and back-extraction solution. This residual oil not only causes extractant loss and reduces metal extraction rate and back-extraction efficiency, but also causes scaling and pipe blockage in subsequent processes. If the oily raffinate and back-extraction solution are directly discharged or enter the deep impurity removal stage, the oil will be adsorbed onto some core processing units, causing surface oil contamination, scaling, and blockage, significantly shortening equipment lifespan, increasing maintenance costs, and interfering with the removal of other impurity ions, thus restricting the preparation of high-purity products. Ultimately, this has become one of the core bottlenecks restricting the high efficiency and clean production of hydrometallurgical processes.

[0003] Existing technologies avoid interference from oil in subsequent processes by removing oil. For example, CN121288418A discloses a method for removing impurities and oil from filter rods used in hydrometallurgical processes for laterite nickel ore: first, a first cleaning solution containing alkaline reagents and surfactants is used to dynamically clean and remove oil stains; then, a second cleaning solution containing acidic reagents and fluorides is used to dynamically clean and remove metallic impurities such as nickel, cobalt, and lead. This step-by-step strategy of "oil removal + impurity removal" achieves deep regeneration of the filter rods, resulting in excellent oil and impurity removal and regeneration performance. However, the alkaline and acidic cleaning systems used in this method are highly corrosive and easily damage the filter rod substrate, requiring high-quality equipment. The fluorine-containing wastewater can easily cause environmental pollution and requires additional treatment. Furthermore, the step-by-step cleaning process is long and the reagent costs are high. At the same time, fluorine metal complexes increase the difficulty of subsequent wastewater treatment.

[0004] Based on the above research, there is a need to provide a composite filter material and oil removal method for removing oil from extraction systems, in order to solve the problems of poor oil removal effect, rapid filter material wear and high operating costs in extraction systems. Summary of the Invention

[0005] The purpose of this invention is to provide a composite filter material and oil removal method for removing oil from an extraction system. The composite filter material adopts a layered structure of upper quartz sand and lower activated carbon, and by controlling the filter layer volume ratio, the SiO2 content in the quartz sand material and the iodine value of the activated carbon material, it achieves graded interception and deep adsorption of floating oil, emulsified oil and dissolved oil in the extraction system.

[0006] To achieve this objective, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a composite filter material for removing oil from an extraction system, the composite filter material comprising a quartz sand filter layer and an activated carbon filter layer stacked together, the activated carbon filter layer being located at the bottom of the quartz sand filter layer;

[0008] The volume ratio of the quartz sand filter layer to the activated carbon filter layer is (1-3):1, for example, it can be 1:1, 1.5:1, 2:1, 2.5:1 or 3:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0009] The quartz sand filter layer includes quartz sand material, and the SiO2 content in the quartz sand material is ≥98wt%, for example, it can be 98wt%, 98.5wt%, 99wt% or 99.5wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0010] The activated carbon filter layer includes activated carbon material with an iodine value ≥800mg / g, such as 800mg / g, 820mg / g, 840mg / g, 860mg / g, 880mg / g or 900mg / g, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0011] The composite filter material of this invention is designed for the characteristics of oil components in the extraction system (mainly emulsified oil and dissolved oil, with few suspended solids). It adopts a layered structure of upper quartz sand and lower activated carbon, and the quartz sand filter layer and activated carbon filter layer are used in a specific volume ratio. This allows the quartz sand filter layer to intercept large droplets, flocculent organic phase and a small amount of suspended solids, and initially adsorb some emulsified oil. The activated carbon filter layer deeply adsorbs dissolved oil, fine emulsified oil and residual organic phase, achieving deep oil removal. This solves the problem that the existing technology does not remove oil thoroughly and cannot meet the requirements of subsequent processing in the extraction process.

[0012] Furthermore, the SiO2 content in the quartz sand material indicates the purity of the quartz sand. This invention uses high-purity quartz sand material, which can ensure the structural strength of the quartz sand filter layer, improve chemical corrosion resistance (for the back-extraction liquid environment), avoid impurities affecting the oil removal effect, and also facilitate the surface modification of the quartz sand. The iodine value of the activated carbon material reflects its micropore quantity and specific surface area. The higher the iodine value of the activated carbon material, the richer the microporous structure inside the activated carbon and the larger the specific surface area of ​​the material, thus the better the adsorption effect of oil. Therefore, this invention uses high-purity quartz sand material and high-iodine-value activated carbon material to specifically improve the oil removal effect of the extraction system.

[0013] Preferably, the particle size D50 of the quartz sand material is 0.5mm-1.2mm, for example, it can be 0.5mm, 0.7mm, 0.9mm, 1.0mm or 1.2mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the particle size D50 of the activated carbon material is 1mm-3mm, for example, it can be 1mm, 1.5mm, 2mm, 2.5mm or 3mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, a support layer is also provided at the bottom of the activated carbon filter layer.

[0016] Preferably, the material of the support layer includes quartz sand particles with a particle size D50 of 8mm-16mm, such as 8mm, 10mm, 12mm, 14mm or 16mm, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] The bottom of the activated carbon filter layer described in this invention is also provided with a support layer made of coarse quartz sand to prevent the filter media from being lost and to ensure the stability of filtration.

[0018] Preferably, the thickness of the support layer is 200mm-300mm, for example, it can be 200mm, 220mm, 240mm, 260mm, 280mm or 300mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the thickness of the quartz sand filter layer is 400mm-600mm, for example, it can be 400mm, 450mm, 500mm, 550mm or 600mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the thickness of the activated carbon filter layer is 200mm-300mm, for example, it can be 200mm, 220mm, 240mm, 260mm, 280mm or 300mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the surface of the quartz sand material is further coated with an oleophilic coating layer.

[0022] This invention modifies the oleophilic properties of quartz sand, forming a hydrophobic and oleophilic coating layer on the surface of the quartz sand, which can further improve the degreasing effect.

[0023] For example, the lipophilic modification method of the present invention includes the following steps:

[0024] Quartz sand material is sequentially acid-washed, water-washed, and dried. Then it is added to an alcohol solution of silane (silane in ethanol or isopropanol) for mixing, followed by filtration and drying to obtain quartz sand material coated with an oleophilic coating layer.

[0025] Preferably, the oleophilic coating layer comprises silane.

[0026] Preferably, the silane comprises alkylsilanes (e.g., octadecyltrichlorosilane) with ≥10 carbon atoms and / or fluorosilanes (e.g., 1H,1H,2H,2H-perfluorodecyltrimethoxysilane).

[0027] Preferably, the oleophilic coating layer is 0.8wt%-5wt% of the mass of the quartz sand material, for example, it can be 0.8wt%, 1.5wt%, 2wt%, 3wt%, 4wt% or 5wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the activated carbon material includes activated carbon material that has undergone activation treatment.

[0029] Preferably, the activation treatment method includes superheated steam activation (medium-low temperature superheated steam activation).

[0030] The superheated steam activation method described in this invention operates as follows: Without the need for inert gas protection or acid / alkali chemical reagents, relying on the factory's common steam medium (mainly water vapor), superheated steam is continuously purged for 2-3.5 hours (e.g., 2 hours, 2.5 hours, 3.0 hours, or 3.5 hours) at 350-550℃ (e.g., 350℃, 450℃, or 550℃). This efficiently removes organic pollutants such as extractants and emulsified oil from the carbon pores, clearing blockages. This process is simple to operate, has low activated carbon burn-off and pulverization rates, low operating costs, and no secondary pollution. It is suitable for oil removal from wet metallurgical extraction residues and allows for long-term recycling of activated carbon.

[0031] Secondly, the present invention provides an oil removal method using the composite filter media described in the first aspect, the oil removal method comprising the following steps:

[0032] An oily solution (such as raffinate or washing water) is passed into the composite filter media as described in the first aspect, so that the oily solution passes through a quartz sand filter layer and an activated carbon filter layer in sequence to obtain an oil-removed liquid.

[0033] The composite filter media of the present invention is filled into the filtration device. The filler consists of a quartz sand filter layer, an activated carbon filter layer and a support layer from top to bottom. The oily solution passes through the composite filter media from top to bottom.

[0034] Preferably, the oil-containing solution is pretreated before being introduced into the composite filter material to remove particles with a particle size D50 ≥ 5 mm, such as 5 mm, 6 mm, 7 mm, 8 mm or 9 mm, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the filtration rate of the oil-containing solution is 6m / h-8m / h, for example, it can be 6m / h, 6.5m / h, 7m / h, 7.5m / h or 8m / h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the oil concentration in the oil-containing solution is 50 mg / L-500 mg / L, for example, it can be 50 mg / L, 100 mg / L, 200 mg / L, 300 mg / L, 400 mg / L or 500 mg / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] This invention allows for adjustment of the volume ratio of quartz sand to activated carbon for different working conditions: when the emulsified oil content in the extraction system is high and the oil concentration is >300mg / L, the volume ratio is adjusted to 1:1; when the oil content in the extraction system is low (<100mg / L) and contains a small amount of suspended matter, the volume ratio is adjusted to 3:1.

[0038] Preferably, the residual oil content in the degreased liquid is ≤5mg / L, for example, it can be 5mg / L, 4mg / L, 3mg / L, 2mg / L or 1mg / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] This invention can treat oily wastewater with oil concentrations of 50-500 mg / L to an effluent residual oil concentration of ≤5 mg / L, and has outstanding advantages such as high oil removal efficiency, long filter media life, low operating cost, and no secondary pollution.

[0040] Preferably, the composite filter material undergoes a backwashing step after oil removal.

[0041] Preferably, the backwashing method includes combined air-water backwashing.

[0042] This invention periodically uses a combined air-water backwash to restore the quartz sand filter layer's interception capacity.

[0043] Preferably, the backwashing air washing intensity is 10 L / (m²). 2 ·s)-15L / (m 2 ·s), for example, could be 10L / (m 2 ·s), 11L / (m 2 ·s), 12L / (m 2·s), 13L / (m 2 ·s), 14L / (m 2 ·s) or 10L / (m 2 ·s), washing strength is 5L / (m 2 ·s)-8L / (m 2 ·s), for example, could be 5L / (m 2 ·s), 6L / (m 2 ·s), 7L / (m 2 ·s) or 8L / (m 2 •s), but not limited to the listed values, other unlisted values ​​within the range also apply.

[0044] Preferably, the backwashing time is 5-10 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes, and the backwashing cycle is 7-10 days (the backwashing cycle can be adjusted according to the influent water quality), for example, 7 days, 8 days, 9 days or 10 days, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Preferably, when the residual oil content of the degreased liquid is >5 mg / L, the activated carbon filter layer in the composite filter material is replaced.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) Highly targeted and efficient in removing oil: The composite filter material described in this invention is specifically adapted to the characteristics of oil in the extraction system (mainly emulsified oil and dissolved oil with few suspended solids). Through a specific volume ratio, it achieves the synergistic effect of "quartz sand coarse filtration and demulsification + activated carbon deep adsorption", which can stably control the residual oil content in the effluent to ≤5mg / L, thus solving the problem that the existing technology does not remove oil thoroughly and does not meet the requirements of subsequent treatment in the extraction process.

[0048] (2) Long service life of filter media and low operating cost: The quartz sand filter layer intercepts the filter media in the front, effectively preventing large oil droplets and suspended matter from clogging the micropores of activated carbon and extending the saturation cycle of activated carbon adsorption. Compared with single activated carbon adsorption, the frequency of activated carbon replacement is reduced by 30%-50%. At the same time, the quartz sand can be backwashed and reused, further reducing the cost of filter media wear.

[0049] (3) Simple process and strong practicality: The filter media is layered and filled, with a simple structure that is easy to fill and replace; the application method is convenient to operate, and the parameters such as filtration rate and backwashing are optimized and reasonable. No complicated equipment is required, and it can be directly applied to the existing extraction process wastewater treatment system. The modification difficulty is low and it is easy to promote industrialization.

[0050] (4) Wide adaptability: It takes into account both oil removal effect and operating economy, and is suitable for oily wastewater treatment in different fields such as hydrometallurgy (nickel, cobalt, copper, etc.) and chemical extraction. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the device after the composite filter material is filled according to Embodiments 1-3 of the present invention.

[0052] Among them, 1-quartz sand filter layer, 2-activated carbon filter layer, 3-support layer, 4-inlet, 5-outlet. Detailed Implementation

[0053] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0054] Example 1

[0055] This embodiment provides a composite filter material for removing oil from an extraction system. The composite filter material includes a quartz sand filter layer, an activated carbon filter layer, and a support layer stacked together. The activated carbon filter layer is located at the bottom of the quartz sand filter layer, and the support layer is located at the bottom of the activated carbon filter layer.

[0056] The volume ratio of the quartz sand filter layer to the activated carbon filter layer is 2:1, the thickness of the quartz sand filter layer is 500 mm, and the thickness of the activated carbon filter layer is 250 mm.

[0057] The quartz sand filter layer includes quartz sand material, the SiO2 content of the quartz sand material is 98.5 wt%, and the particle size D50 of the quartz sand material is 0.8 mm;

[0058] The activated carbon filter layer includes activated carbon material (coal-based granular activated carbon), the iodine value of the activated carbon material is 850 mg / g, and the particle size D50 of the activated carbon material is 2 mm;

[0059] The thickness of the support layer is 250 mm, and the material of the support layer includes quartz sand particles with a particle size D50 of 10 mm.

[0060] This embodiment also provides a degreasing method, which includes the following steps:

[0061] (1) The composite filter material described in this embodiment is filled into the filtration device. The structural diagram after filling is shown in the figure below. Figure 1 As shown, the upper end is provided with an inlet 4, the bottom is provided with an outlet 5, and the interior is filled from top to bottom with a quartz sand filter layer 1, an activated carbon filter layer 2 and a support layer 3.

[0062] (2) The raffinate (containing 200 mg / L of oil, mainly emulsified oil and P204 extractant) produced by the wet metallurgical cobalt extraction process is filtered to remove large particulate impurities;

[0063] (3) The raffinate is passed through the composite filter media from top to bottom at a filtration rate of 7 m / h to remove oil in stages, and the oil-removed liquid is obtained.

[0064] (4) The composite filter media shall be backwashed with a combination of air and water every 8 days (the air washing intensity is 12L / (m)). 2 ·s), washing strength 5L / (m 2 (·s), backwashing time 8min), after 30 days of long-term operation, the residual oil content in the effluent is still ≤4mg / L, the activated carbon has not reached adsorption saturation, and the quartz sand filter layer has good interception capacity.

[0065] In this embodiment, the residual oil content in the effluent is stable at 3-4 mg / L, which meets the influent requirements of the subsequent resin adsorption process. The activated carbon replacement cycle can reach more than 60 days, which reduces the replacement frequency by 40% compared with single activated carbon adsorption.

[0066] Example 2

[0067] This embodiment provides a composite filter material for removing oil from an extraction system. The composite filter material includes a quartz sand filter layer, an activated carbon filter layer, and a support layer stacked together. The activated carbon filter layer is located at the bottom of the quartz sand filter layer, and the support layer is located at the bottom of the activated carbon filter layer.

[0068] The volume ratio of the quartz sand filter layer to the activated carbon filter layer is 1:1, the thickness of the quartz sand filter layer is 300mm, and the thickness of the activated carbon filter layer is 300mm.

[0069] The quartz sand filter layer includes quartz sand material, the SiO2 content of the quartz sand material is 99wt%, and the particle size D50 of the quartz sand material is 1mm;

[0070] The activated carbon filter layer includes activated carbon material (coconut shell granular activated carbon), the iodine value of the activated carbon material is 900 mg / g, and the particle size D50 of the activated carbon material is 1.5 mm;

[0071] The thickness of the support layer is 200 mm, and the material of the support layer includes quartz sand particles with a particle size D50 of 12 mm.

[0072] This embodiment also provides a degreasing method, which includes the following steps:

[0073] (1) The composite filter material described in this embodiment is filled into the filtration device. The structural diagram after filling is shown in the figure below. Figure 1As shown, the upper end is provided with an inlet 4, the bottom is provided with an outlet 5, and the interior is filled from top to bottom with a quartz sand filter layer 1, an activated carbon filter layer 2 and a support layer 3.

[0074] (2) The oily wastewater (with an oil concentration of 400 mg / L, severe emulsification, and a small amount of kerosene diluent) generated by the chemical copper extraction process is filtered to remove large particulate impurities;

[0075] (3) The raffinate is passed through the composite filter media from top to bottom at a filtration rate of 6 m / h to remove oil in stages, and the oil-removed liquid is obtained.

[0076] (4) The composite filter media shall be backwashed with a combination of air and water every 7 days (the air washing intensity is 15L / (m)). 2 ·s), washing strength 8L / (m 2 (·s), backwash time 10min), long-term operation for 25 days, residual oil content in effluent ≤5mg / L, activated carbon adsorption is close to saturation, can continue to operate after replacing activated carbon.

[0077] This embodiment targets extraction wastewater with high oil content and high emulsification. By using a 1:1 filter media ratio, the deep adsorption effect is enhanced, and the residual oil content in the effluent meets the discharge standards, thus solving the problem of difficult removal of highly emulsified oil.

[0078] Example 3

[0079] This embodiment provides a composite filter material for removing oil from an extraction system. The composite filter material includes a quartz sand filter layer, an activated carbon filter layer, and a support layer stacked together. The activated carbon filter layer is located at the bottom of the quartz sand filter layer, and the support layer is located at the bottom of the activated carbon filter layer.

[0080] The volume ratio of the quartz sand filter layer to the activated carbon filter layer is 3:1, the thickness of the quartz sand filter layer is 600mm, and the thickness of the activated carbon filter layer is 200mm.

[0081] The quartz sand filter layer includes quartz sand material, the SiO2 content of the quartz sand material is 98wt%, and the particle size D50 of the quartz sand material is 0.5mm;

[0082] The activated carbon filter layer includes activated carbon material (coal-based granular activated carbon), the iodine value of the activated carbon material is 800 mg / g, and the particle size D50 of the activated carbon material is 3 mm;

[0083] The thickness of the support layer is 300 mm, and the material of the support layer includes quartz sand particles with a particle size D50 of 8 mm.

[0084] This embodiment also provides a degreasing method, which includes the following steps:

[0085] (1) The composite filter material described in this embodiment is filled into the filtration device. The structural diagram after filling is shown in the figure below. Figure 1 As shown, the upper end is provided with an inlet 4, the bottom is provided with an outlet 5, and the interior is filled from top to bottom with a quartz sand filter layer 1, an activated carbon filter layer 2 and a support layer 3.

[0086] (2) Filter the washing water (containing 80 mg / L of oil and a small amount of suspended solids) generated from the nickel extraction process to remove large particulate impurities;

[0087] (3) The raffinate is passed through the composite filter media from top to bottom at a filtration rate of 8 m / h to remove oil in stages, and the oil-removed liquid is obtained.

[0088] (4) The composite filter media shall be backwashed with a combination of air and water every 10 days (the air washing intensity is 10L / (m)). 2 ·s), washing strength 5L / (m 2 With a backwashing time of 5 minutes (·s), after 40 days of long-term operation, the residual oil content in the effluent is ≤3mg / L, and both the quartz sand filter layer and the activated carbon filter layer maintain good treatment effect.

[0089] This embodiment targets extraction wastewater with low oil content and a small amount of suspended solids. By using a 3:1 filter media ratio, the interception effect is enhanced, activated carbon consumption is reduced, and operating costs are further reduced, while ensuring the oil removal effect.

[0090] Example 4

[0091] This embodiment provides a composite filter material for removing oil from an extraction system. Except for the quartz sand material being coated with a 1H,1H,2H,2H-perfluorodecyltrimethoxysilane coating layer (the coating layer is 2 wt% of the mass of the quartz sand material), the composite filter material is the same as in Example 1.

[0092] This embodiment also provides an oil removal method, which is the same as that in Embodiment 1 except that it uses the composite filter material of this embodiment.

[0093] The oil removal method described in this embodiment operates for 30 days, and the residual oil content in the effluent is within the range of 2-4 mg / L.

[0094] Example 5

[0095] This embodiment provides a composite filter material for removing oil from an extraction system. Except for the quartz sand material being coated with an octadecyltrichlorosilane coating layer (the coating layer is 5 wt% of the mass of the quartz sand material), the composite filter material is the same as in Example 1.

[0096] This embodiment also provides an oil removal method, which is the same as that in Embodiment 1 except that it uses the composite filter material of this embodiment.

[0097] The oil removal method described in this embodiment operates for 30 days, and the residual oil content in the effluent is in the range of 2-3 mg / L. Therefore, as can be seen from the comparison between Example 1 and Examples 4-5, the oleophilic coating layer on the surface of the quartz sand material described in this invention can further improve the oil removal efficiency.

[0098] Comparative Example 1

[0099] This comparative example provides a composite filter material for removing oil from an extraction system. The composite filter material is the same as in Example 1, except that the volume ratio of the quartz sand filter layer to the activated carbon filter layer is 0.5:1, the thickness of the quartz sand filter layer is 250 mm, and the thickness of the activated carbon filter layer is 500 mm.

[0100] This comparative example also provides an oil removal method, which is the same as that in Example 1 except that it uses the composite filter material of this comparative example.

[0101] The oil removal method described in this comparative example operated for 30 days, and the residual oil content in the effluent was in the range of 10-15 mg / L.

[0102] Comparative Example 2

[0103] This comparative example provides a composite filter material for removing oil from an extraction system. The composite filter material is the same as in Example 1, except that the volume ratio of the quartz sand filter layer to the activated carbon filter layer is 4:1, the thickness of the quartz sand filter layer is 600 mm, and the thickness of the activated carbon filter layer is 150 mm.

[0104] This comparative example also provides an oil removal method, which is the same as that in Example 1 except that it uses the composite filter material of this comparative example.

[0105] The oil removal method described in this comparative example operated for 30 days, and the residual oil content in the effluent was within the range of 20-30 mg / L. A comparison of Example 1 and Comparative Examples 1-2 shows that this invention, by controlling the volume ratio of the quartz sand filter layer and the activated carbon filter layer in the composite filter media, can leverage the synergistic effect of coarse filtration and demulsification by quartz sand and deep adsorption by activated carbon, achieving a deep oil removal effect.

[0106] Comparative Example 3

[0107] This comparative example provides a composite filter material for removing oil from an extraction system. Except for the SiO2 content of the quartz sand material being 97wt% and the iodine value of the activated carbon material being 750mg / g, the composite filter material is the same as that in Example 1.

[0108] This comparative example also provides an oil removal method, which is the same as that in Example 1 except that it uses the composite filter material of this comparative example.

[0109] The oil removal method described in this comparative example operated for 30 days, and the residual oil content in the effluent was within the range of 10-20 mg / L. A comparison between Example 1 and Comparative Example 3 shows that the present invention, by using high-purity quartz sand and high-iodine-value activated carbon, can enhance the interception and adsorption effect of quartz sand and strengthen the adsorption capacity of activated carbon for dissolved and emulsified oil, thereby improving the oil removal effect.

[0110] Comparative Example 4

[0111] This comparative example provides a composite filter material for removing oil from an extraction system. The composite filter material is the same as in Example 1, except that the positions of the quartz sand filter layer and the activated carbon filter layer are interchanged.

[0112] This comparative example also provides an oil removal method, which is the same as that in Example 1 except that it uses the composite filter material of this comparative example.

[0113] The oil removal method described in this comparative example operated for 30 days, and the residual oil content in the effluent was in the range of 8-15 mg / L. A comparison between Example 1 and Comparative Example 4 shows that the activated carbon filter layer of this invention is located at the bottom of the quartz sand filter layer. The oily solution needs to first pass through the quartz sand filter layer to intercept large droplets, flocculent organic phases, and a small amount of suspended matter, initially adsorbing some of the emulsified oil, before undergoing deep oil removal through the activated carbon filter layer to achieve deep oil removal.

[0114] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A composite filter media for removing oil from an extraction system, characterized in that, The composite filter media includes a quartz sand filter layer and an activated carbon filter layer stacked together, with the activated carbon filter layer located at the bottom of the quartz sand filter layer; The volume ratio of the quartz sand filter layer to the activated carbon filter layer is (1-3):1; The quartz sand filter layer includes quartz sand material, wherein the SiO2 content of the quartz sand material is ≥98wt%; The activated carbon filter layer includes activated carbon material, and the iodine value of the activated carbon material is ≥800mg / g.

2. The composite filter media for removing oil from an extraction system according to claim 1, characterized in that, The particle size D50 of the quartz sand material is 0.5mm-1.2mm; Preferably, the particle size D50 of the activated carbon material is 1mm-3mm.

3. The composite filter media for removing oil from an extraction system according to claim 1 or 2, characterized in that, The bottom of the activated carbon filter layer is also provided with a support layer; Preferably, the material of the support layer comprises quartz sand particles with a particle size D50 of 8mm-16mm; Preferably, the thickness of the support layer is 200mm-300mm.

4. The composite filter media for removing oil from an extraction system according to claim 1 or 2, characterized in that, The thickness of the quartz sand filter layer is 400mm-600mm; Preferably, the thickness of the activated carbon filter layer is 200mm-300mm.

5. The composite filter media for removing oil from an extraction system according to claim 1 or 2, characterized in that, The surface of the quartz sand material is also coated with an oleophilic coating layer; Preferably, the lipophilic coating layer comprises silane; Preferably, the silane comprises alkylsilanes and / or fluorosilanes with ≥10 carbon atoms; Preferably, the oleophilic coating layer is 0.8wt%-5wt% of the mass of the quartz sand material.

6. The composite filter media for removing oil from an extraction system according to claim 1 or 2, characterized in that, The activated carbon material includes activated carbon material that has undergone activation treatment; Preferably, the activation treatment method includes superheated steam activation.

7. An oil removal method using the composite filter media as described in any one of claims 1-6, characterized in that, The degreasing method includes the following steps: An oily solution is passed through the composite filter media as described in any one of claims 1-6, so that the oily solution passes through a quartz sand filter layer and an activated carbon filter layer in sequence to obtain an oil-removed liquid.

8. The degreasing method according to claim 7, characterized in that, Before the oil-containing solution is introduced into the composite filter media, it is pretreated to remove particles with a particle size D50 ≥ 5 mm. Preferably, the filtration rate of the oil-containing solution is 6 m / h-8 m / h; Preferably, the oil concentration in the oil-containing solution is 50 mg / L-500 mg / L; Preferably, the residual oil content in the degreased liquid is ≤5mg / L.

9. The degreasing method according to claim 7 or 8, characterized in that, The composite filter media underwent a backwashing step after oil removal; Preferably, the backwashing method includes combined air-water backwashing; Preferably, the backwashing air washing intensity is 10 L / (m²). 2 ·s)-15L / (m 2 ·s), washing strength is 5L / (m 2 ·s)-8L / (m 2 ·s); Preferably, the backwashing time is 5-10 minutes, and the backwashing cycle is 7-10 days.

10. The degreasing method according to claim 7 or 8, characterized in that, When the residual oil content of the degreased liquid is >5 mg / L, replace the activated carbon filter layer in the composite filter material.

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