Method for removing oil from raffinate by means of steam

Abstract

The present application relates to the technical field of hydrometallurgy, and provides a method for removing oil from a raffinate by means of steam. The method comprises: introducing a medium-temperature circulating waste gas into a raffinate, and separating and filtering same to obtain a which has been subjected to first-stage coalescence; introducing high-temperature steam into the effluent which has been subjected to first-stage coalescence so as to perform demulsification and inactivation, and separating and filtering same to obtain an effluent which has been subjected to second-stage coalescence; making the effluent which has been subjected to second-stage coalescence sequentially flow through a first metal-fiber filter layer into which high-temperature steam is introduced and a second metal-fiber filter layer into which low-temperature air is introduced, and performing two-stage filtration to obtain an effluent which has been subjected to second-stage filtration; and performing activated-carbon adsorption and removal on the effluent which has been subjected to second-stage filtration, so as to obtain an effluent from which oil is removed. In the present application, by means of a multi-stage combined treatment process consisting of sequential gas flotation and coalescence using a medium-temperature gas, demulsification using high-temperature steam, metal fiber coalescence and filtration using high-temperature steam and low-temperature air, activated-carbon adsorption, etc., the removal rate of an oil phase from the raffinate is higher, no impurities are introduced, heat recycling is achieved, and continuous production can be realized.

Description

A method for steam deoiling of raffinate

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202410338627.1, filed with the Patent Office of China on March 25, 2024, entitled “A method for steam deoiling of raffinate”; the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of hydrometallurgy, and in particular to a method for steam deoiling of raffinate. Background Art

[0004] Extraction is a very effective separation method for metal separation in hydrometallurgy. It uses the different distribution abilities of metal ions (such as Cu, Co or Ni) between the organic phase (such as P204-kerosene, P507-kerosene or C272-kerosene) and the aqueous phase to achieve the purpose of separation and enrichment. The aqueous phase remaining after extraction is the raffinate. Due to the strong mixing of the organic phase and the aqueous phase during the extraction process, the organic phase inevitably dissolves or remains in the aqueous phase. The organic phase remaining in the raffinate will cause a series of problems for subsequent processes.

[0005] Domestic and foreign scholars have conducted extensive research on the removal of oil from raffinate, mainly including the following methods: ultrasonic method, flotation method, fiber ball filtration / fiber aggregation method, membrane separation method, resin adsorption method, activated carbon adsorption method, coagulation method, advanced oxidation method and other technical methods. Although these methods can remove part of the oil, they all have various problems. For example, ultrasonic oil removal is costly and has poor oil removal effect; although flotation oil removal is simple to operate and low in cost, it has poor oil removal effect and requires multiple processes for combined treatment; activated carbon oil removal is effective, but the amount of activated carbon used is large and the operating cost is high, and it is only suitable for removing low-content oil; adsorption method is costly, and the adsorbent is difficult to handle after use, causing secondary pollution; advanced oxidation method converts oil into small molecular carbon and nitrogen oxides, and is currently limited to laboratory research.

[0006] In existing research, researchers have designed a cyclone flotation oil-water separation device and flotation generator to address the limited oil concentration range of flotation treatment. Similarly, researchers have developed a cold air flotation oil removal method and device. By introducing cold air into the solution, dissolved oil is precipitated and removed by flotation. This method is simple, economical, and highly efficient. However, these methods are only suitable for deoiling water or dilute solutions during crude oil extraction, and are not suitable for deoiling high-concentration salt solutions.

[0007] Some researchers have proposed a method for deep COD removal from nickel-cobalt raffinate. This method first subjects the wastewater to coagulation and demulsification treatment, converts the emulsified oil into suspended oil, and then enters flotation deoiling treatment to remove the suspended oil. It then undergoes adsorption treatment for deep oil removal, and further undergoes ozone catalytic oxidation for deep treatment. Although the deoiling effect is good, the treatment cost is too high. In addition, researchers have proposed a method for treating cobalt-nickel raffinate. This method includes three steps: flotation deoiling - coagulation and sedimentation deoiling - activated carbon adsorption to remove COD and P. It can reduce the COD in the cobalt-nickel raffinate to below 100 mg / L, the P content to below 3 mg / L, and the oil content to below 20 mg / L. However, this method requires the pH of the extract to be adjusted to 7-8, and is not suitable for acidic systems.

[0008] Therefore, there is an urgent need to research and develop a new oil removal method that is configured to remove the oil phase remaining in the raffinate.

[0009] Application Contents

[0010] The purpose of the present application is to provide a method for steam deoiling of raffinate, by using medium-temperature circulating gas for flotation and coalescence - high-temperature steam is used to modify, demulsify and inactivate the oil particles in the raffinate, and then through hot / cold two-stage coalescence and solidification filtration, the oil particles are floated and coalesced under the action of bubbles, and solidified and coalesced under the action of the fiber layer to achieve oil removal.

[0011] To achieve the above objectives, the technical solutions of this application are as follows:

[0012] The present application provides a method for steam deoiling of raffinate, comprising:

[0013] S1: introducing medium-temperature circulating waste gas into the raffinate, separating and filtering to obtain the first-stage coalesced liquid;

[0014] S2: passing high-temperature steam into the first-stage coalesced liquid to demulsify and inactivate the liquid, and then separating and filtering to obtain the second-stage coalesced liquid;

[0015] S3: passing the secondary coalesced liquid through a first metal fiber filter layer into which high-temperature steam is passed and a second metal fiber filter layer into which low-temperature air is passed, performing two-stage filtration to obtain a secondary filtered liquid;

[0016] S4: The secondary filtered liquid is subjected to activated carbon adsorption removal to obtain a deoiled liquid.

[0017] Preferably, the temperature of the medium-temperature circulating exhaust gas is 45°C-115°C.

[0018] Preferably, the temperature of the high-temperature steam is 115°C-450°C.

[0019] Preferably, the temperature of the low-temperature air is -25°C-32°C.

[0020] Preferably, the medium-temperature circulating exhaust gas comes from the secondary gas recovered from S2 and S3.

[0021] Preferably, the material of the first metal fiber filter layer and the second metal fiber filter layer independently includes at least one of titanium and stainless steel;

[0022] And / or, the metal fibers in the first metal fiber filter layer and the second metal fiber filter layer are each independently in a felt shape or formed by stacking small balls;

[0023] And / or, the high-temperature steam is introduced from the bottom of the first metal fiber filter layer from bottom to top, and the low-temperature air is introduced from the bottom of the second metal fiber filter layer from bottom to top.

[0024] Preferably, the introduction rate of high-temperature steam in S2 is higher than the introduction rate of high-temperature steam in the first metal fiber filter layer in S3.

[0025] Preferably, when the secondary coalesced liquid flows through the first metal fiber filter layer and the second metal fiber filter layer in sequence, the oil particles in the secondary coalesced liquid undergo hot interface coalescence at the gas-liquid-solid interface of the first metal fiber filter layer and undergo sudden cooling and solidification coalescence at the gas-liquid-solid interface of the second metal fiber filter layer. After the two-stage filtration, the oil particles are respectively attached to the surface of the first metal fiber filter layer and the surface of the second metal fiber filter layer to form oil-containing metal fibers.

[0026] Further preferably, the oil-containing metal fibers are regenerated by high-temperature thermal decomposition to form oil-free metal fibers, and the temperature of the high-temperature thermal decomposition is 230°C-850°C.

[0027] Preferably, the thickness of the first metal fiber filter layer and the second metal fiber filter layer are independently 100 mm to 250 mm.

[0028] Beneficial effects of this application:

[0029] In the method for steam deoiling of raffinate provided in the present application, the raffinate is first preheated and heated by medium-temperature exhaust gas, and the oil particles are subjected to a first-stage medium-temperature flotation and agglomeration; then, the oil particles are denatured, demulsified, inactivated, and flotation and agglomeration are performed by high-temperature steam; and then, the oil particles are filtered by a two-stage filtration process of a first-stage high-temperature fiber agglomeration and a first-stage quenching, oil separation, solidification, and agglomeration. This achieves deep removal of the oil phase in the raffinate, and no new impurities are introduced during the entire treatment process, which has no impact on the system and is easy to industrialize.

[0030] At the same time, the present application adopts a multi-stage combined treatment process by sequentially performing steam demulsification, high-temperature steam-low-temperature air metal fiber agglomeration filtration, and activated carbon adsorption, so that the removal rate of the oil phase in the raffinate is higher and continuous process production can be achieved.

[0031] Furthermore, the method for steam deoiling of raffinate provided in the present application fully utilizes the medium-temperature waste gas formed after the steam is cooled and the cold air is heated, uses the heat of the medium-temperature waste gas to preheat the raffinate, and uses the medium-temperature waste gas for primary flotation aggregation, thereby improving gas utilization and energy utilization.

[0032] In addition, in the method for steam deoiling of raffinate provided in the present application, the oil-containing metal fibers obtained by the two-stage three-phase interface coalescence filtration of high-temperature metal fibers and low-temperature metal fibers can be regenerated and recycled, further reducing production costs and widening the scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0034] FIG1 is a schematic flow diagram of a process for steam deoiling of raffinate provided in Example 1;

[0035] FIG2 is a schematic diagram of solution filtration by the metal fiber filter layer in step (3) or step (4) of Example 1. DETAILED DESCRIPTION

[0036] As used herein:

[0037] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus. The conjunction "consisting of" excludes any unspecified element, step, or component.

[0038] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0039] In these examples, parts and percentages are by mass unless otherwise indicated.

[0040] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the mass of all components is not limited to 100 parts.

[0041] “And / or” is configured to mean that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0042] The present application provides a method for steam deoiling of raffinate, comprising:

[0043] S1: introducing medium-temperature circulating waste gas into the raffinate, separating and filtering to obtain the first-stage coalesced liquid;

[0044] S2: passing high-temperature steam into the first-stage coalesced liquid to demulsify and inactivate the liquid, and then separating and filtering to obtain the second-stage coalesced liquid;

[0045] S3: passing the secondary coalesced liquid through a first metal fiber filter layer into which high-temperature steam is passed and a second metal fiber filter layer into which low-temperature air is passed, performing two-stage filtration to obtain a secondary filtered liquid;

[0046] S4: The secondary filtered liquid is subjected to activated carbon adsorption removal to obtain a deoiled liquid.

[0047] In one embodiment of the present application, the temperature of the medium-temperature circulating exhaust gas in S1 is 45°C-115°C, for example, it can be 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 115°C or any value between 45°C and 115°C.

[0048] In one embodiment of the present application, the temperature of the high-temperature steam in S2 and S3 is 115°C-450°C, for example, it can be 115°C, 120°C, 150°C, 180°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C or any value between 115°C-450°C.

[0049] In one embodiment of the present application, the temperature of the low-temperature air introduced into S3 is -25℃-32℃, for example, it can be -25℃, -20℃, -10℃, 0℃, 5℃, 10℃, 20℃, 30℃, 32℃ or any value between -25℃-32℃.

[0050] In one embodiment of the present application, the medium-temperature circulating exhaust gas in S1 is derived from the secondary gases recovered in S2 and S3. Specifically, it includes the exhaust gas generated by the high-temperature steam in S2 passing through the solution and then cooling down, and the medium-temperature exhaust gas generated by the high-temperature steam in S3 cooling down and the low-temperature air heating up.

[0051] In one embodiment of the present application, the material of the first metal fiber filter layer and the second metal fiber filter layer independently includes at least one of titanium and stainless steel.

[0052] It is particularly noted that the metal fiber material selected is mainly a metal material that does not react with the raffinate.

[0053] In one embodiment of the present application, the metal fibers in the first metal fiber filter layer and the second metal fiber filter layer are each independently in the form of felt or stacked balls.

[0054] In one embodiment of the present application, high-temperature steam or low-temperature air is introduced from the bottom of the metal fiber filter layer from bottom to top.

[0055] In one embodiment of the present application, the high-temperature steam introduction rate in S2 is higher than the high-temperature steam introduction rate in the first metal fiber filter layer in S3. This is mainly because a large amount of high-temperature steam is required in S2 to demulsify and deactivate the raffinate.

[0056] In one embodiment of the present application, performing two-stage filtration in S3 to obtain a secondary filtered liquid specifically includes:

[0057] S301. Pass the secondary coalesced liquid into the first metal fiber filter layer, and at the same time, spray high-temperature steam into the first metal fiber filter layer to perform thermal coalescence and floating of the gas-liquid-solid three-phase interface of steam-solution-metal fiber. The oil phase particles coalesce and float under the action of the high-temperature steam. When passing through the first metal fiber filter layer, they adhere to the surface of the first metal fiber filter layer to form oil-containing metal fibers. At this time, the filtered solution is the primary filtered liquid.

[0058] S302. The primary filtered liquid obtained by filtration in S301 is passed into the second metal fiber filter layer. At the same time, low-temperature air is sprayed into the second metal fiber filter layer to perform rapid cooling, solidification and agglomeration of the three-phase interface of low-temperature air-solution-metal fiber. Oil phase particles are precipitated under the action of the cold air and eventually adhere to the surface of the second metal fiber filter layer to form oil-containing metal fibers. The solution obtained by filtration at this time is the secondary filtered liquid.

[0059] In one embodiment of the present application, the oil-containing metal fibers formed in S301 and S302 can be thermally decomposed at high temperature to regenerate into oil-free metal fibers.

[0060] Specifically, the temperature of high-temperature thermal decomposition is 230℃-850℃, for example, it can be 230℃, 250℃, 300℃, 350℃, 400℃, 500℃, 600℃, 700℃, 800℃, 850℃ or any value between 230℃-850℃.

[0061] In one embodiment of the present application, the thickness of the first metal fiber filter layer and the second metal fiber filter layer in S3 are independently 100 mm to 250 mm. For example, the thickness of the first metal fiber filter layer can be 100 mm and the thickness of the second metal fiber filter layer can be 200 mm, or the thickness of the first metal fiber filter layer can be 150 mm and the thickness of the second metal fiber filter layer can be 250 mm, or the thickness of the first metal fiber filter layer can be 200 mm and the thickness of the second metal fiber filter layer can be 200 mm. The thicknesses of the two metal fiber filter layers can be the same or different.

[0062] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are only configured to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0063] Example 1

[0064] As shown in FIG1 , this embodiment provides a process for steam deoiling of raffinate, which specifically includes the following steps:

[0065] (1) 10 L of zinc extraction raffinate from the P204 extraction process in zinc smelting, with an oil content of 140 mg / L, was taken. Medium-temperature circulating gas at a temperature of 95°C was introduced into the solution to preheat the raffinate to a temperature of above 70°C. The solution was vigorously stirred with the gas to flotate and aggregate the P204-kerosene particles contained in the solution. The reaction was terminated after 1.5 h. The oil phase suspended on the liquid surface was filtered and separated to obtain a first-stage aggregated liquid.

[0066] (2) Steam at 150°C was introduced into the first-stage coalesced liquid at high speed to perform high-temperature denaturation and demulsification of the P204-kerosene particles and coalescence and floating of microbubbles. The ventilation time was 2 h, and continuous stirring was performed to enhance the coalescence effect. After the ventilation was completed, the oil phase suspended on the liquid surface was filtered and separated to obtain the second-stage coalesced liquid.

[0067] (3) The secondary coalesced liquid is passed through a titanium wire ball filter layer with a thickness of 150 mm. At the same time, steam at 150°C is slowly sprayed upward from the bottom of the titanium wire ball filter layer for 40 minutes (as shown in Figure 2) to perform thermal coalescing and floating at the steam-metal fiber-solution three-phase interface. The P204-kerosene particles coalesce and float under the action of steam. When passing through the metal fiber filter layer, the P204-kerosene particles adhere to the surface of the metal fiber to form oil-containing metal fibers. The remaining solution is the primary filtered liquid.

[0068] (4) The first-stage filtered liquid obtained in step (3) is passed into a titanium wire spherical filter layer with a thickness of 200 mm, and at the same time, air at 5°C is slowly sprayed upward at the bottom of the titanium wire spherical filter layer for 2 hours to perform rapid cooling, solidification and agglomeration of the low-temperature air-metal fiber-solution three-phase interface. The P204-kerosene particles are further precipitated and agglomerated under the action of the cold air, and are stably solidified and attached to the titanium wire spherical filter layer under the action of microbubbles to form oil-containing metal fibers and filtered liquid, i.e., the second-stage filtered liquid.

[0069] (5) Add 50 g of porous activated carbon to the secondary filtered liquid obtained in step (4), stir for 2 h, and perform deep adsorption removal of the activated carbon. After solid-liquid separation, the activated carbon is returned for recycling. The adsorbed liquid obtained is the deoiled liquid, and the oil content is 0.48 mg / L.

[0070] (6) The oil-containing metal fibers obtained in step (3) and step (4) are calcined at 325° C. for 4 h for thermal decomposition, and the obtained fibers are regenerated oil-free metal fibers.

[0071] (7) After the secondary gases in step (2), step (3) and step (4) are recovered and combined, they are sent to step (1) for use as medium-temperature circulating gas.

[0072] Example 2

[0073] This embodiment provides a process for steam deoiling of raffinate, which is the same as that of Example 1, except that the temperature of the steam introduced in steps (2) and (3) is 300°C, the remaining steps remain unchanged, and the oil content of the deoiled liquid in step (5) is less than 0.21 mg / L.

[0074] Example 3

[0075] This embodiment provides a process for steam deoiling of raffinate, which is the same as that of embodiment 1, except that mechanical stirring is performed after the medium-temperature circulating gas is introduced in step (1) and after the steam is introduced in step (2) to enhance the contact between the gas and the solution. The stirred solution flows into a standing tank for standing clarification, and the oil particles float to the surface. The oil phase suspended on the surface of the liquid is filtered and separated to obtain the corresponding coalesced filtered liquid.

[0076] The oil content in the deoiled liquid finally obtained in this embodiment is less than 0.46 mg / L.

[0077] Example 4

[0078] This embodiment provides a process for steam deoiling of raffinate, which is the same as that of Example 1, except that the thickness of the titanium wire ball filter layer in step (3) is 250 mm.

[0079] The oil content in the deoiled liquid finally obtained in this embodiment is less than 0.38 mg / L.

[0080] Example 5

[0081] This embodiment provides a process for removing oil from raffinate by steam, which specifically includes:

[0082] (1) A medium-temperature circulating gas (secondary gas recovered from subsequent processes) with a temperature of 75°C-92°C was introduced into the P507 nickel extraction residual liquid (oil content 237 mg / L) in the ternary battery waste recycling workshop to perform heating flotation agglomeration to agglomerate the oil particles remaining in the extraction process. After reacting for 0.5 h, the oil phase was filtered and separated to obtain a first-level agglomerated liquid.

[0083] (2) Steam at 240°C is introduced into the first-stage coalesced liquid for strong stirring to denature the residual oil particles at high temperature, i.e., demulsify and inactivate them. After reacting for 1.4 hours, the oil phase is filtered and separated to obtain the second-stage coalesced liquid.

[0084] (3) The secondary coalesced liquid is then passed through a 200 mm thick steel ball filter layer, and steam at 240°C is slowly sprayed into the steel ball filter layer for 30 minutes. When the treated solution slowly flows through the steel fiber filter layer, the deformed and inactivated organic matter solidifies and adheres to the steel ball filter layer, forming oil-containing metal fibers and the primary filtered liquid.

[0085] (4) The first-stage filtered liquid is continued to be passed into a steel ball filter layer with a thickness of 200 mm. At the same time, cold air at -10°C is slowly sprayed into the steel ball filter layer for 15 minutes. The pores of the steel ball filter layer are quenched, solidified, and agglomerated. The oil particles are further stably solidified in the pores of the steel ball filter layer to form oil-containing metal fibers and filtered liquid, i.e., the second-stage filtered liquid.

[0086] (5) Porous activated carbon particles are sprinkled into the secondary filtered liquid to perform deep adsorption removal of the activated carbon. After solid-liquid separation, the adsorbed liquid obtained is the deoiled liquid, and the oil content is less than 0.64 mg / L.

[0087] (6) The oil-containing metal fiber is baked in a furnace at 280°C for 30 minutes, and the dust is washed to obtain the regenerated oil-free metal fiber.

[0088] Comparative Example 1

[0089] This comparative example provides a process for steam deoiling of raffinate, which specifically comprises the following steps:

[0090] (1) 10 L of zinc extraction raffinate from the P204 extraction process in zinc smelting, with an oil content of 140 mg / L, was taken and a medium-temperature circulating gas (from secondary gas recovered after use in subsequent processes) at a temperature of 95°C was introduced into the solution. The raffinate was preheated and subjected to primary flotation and coalescence, and then filtered to obtain a primary coalescence liquid.

[0091] (2) Steam at 150°C is then introduced into the first-stage coalesced liquid at high speed to perform high-temperature denaturation and demulsification of the P204-kerosene particles and coalescence and floating of microbubbles. The ventilation time is 2 hours, and continuous stirring is performed to enhance the coalescence effect. After the ventilation is completed, the oil phase suspended on the liquid surface is filtered and separated to obtain the second-stage coalesced liquid.

[0092] (3) Add 50g of porous activated carbon to the secondary coalescence liquid and stir for 2h to perform deep adsorption removal of activated carbon. After solid-liquid separation, the activated carbon is returned for recycling. The adsorbed liquid obtained is the deoiled liquid with an oil content of 95.43mg / L.

[0093] Compared to Example 1, the raw material used was the same solution, differing only in that this comparative example performed medium-temperature gas preheating flotation, high-temperature steam demulsification and coalescence, and activated carbon adsorption, but did not perform hot filtration at the steam-metal fiber-solution three-phase interface or quench filtration at the low-temperature air-metal fiber-solution three-phase interface. Sampling analysis after the reaction revealed an oil content of 95.43 mg / L in the deoiled solution. Compared to the raw material, the oil content in the deoiled solution obtained in this comparative example was still relatively high, resulting in a low oil removal rate.

[0094] Comparative Example 2

[0095] This comparative example provides a process for steam deoiling of raffinate, which is the same as that of Example 1, except that: after step (3), 50 g of porous activated carbon is directly added to the obtained primary filtered liquid, and the mixture is stirred for 2 h to perform deep adsorption removal by the activated carbon. After solid-liquid separation, the activated carbon is returned for recycling, and the obtained adsorbed liquid is the deoiled liquid, and the oil content is 35.62 mg / L.

[0096] Compared with Example 1, this comparative example did not perform quench filtration at the low-temperature air-metal fiber-solution three-phase interface. Sampling analysis after the reaction showed that the oil content in the deoiled solution was 35.62 mg / L, indicating a low oil removal rate.

[0097] Comparative Example 3

[0098] This comparative example provides a process for steam deoiling of raffinate, which is the same as Example 1, except that: in step (3), the secondary coalesced liquid is passed into a titanium wire spherical filter layer with a thickness of 200 mm, and at the same time, air at 5°C is slowly sprayed into the titanium wire spherical filter layer for 2 hours to perform cold coalescence at the low-temperature air-metal fiber-solution three-phase interface. The P204-kerosene particles are further precipitated and coalesced under the action of the cold air, and are stably attached to the titanium wire spherical filter layer under the action of microbubbles to form oil-containing metal fibers and the primary filtered liquid.

[0099] Then, 50g of porous activated carbon was added to the first-stage filtered liquid and stirred for 2h for deep adsorption and removal of activated carbon. After solid-liquid separation, the activated carbon was returned for recycling. The filtrate obtained was the deoiled liquid with an oil content of 52.43mg / L.

[0100] Compared with Example 1, this comparative example did not perform hot filtration at the high-temperature steam-metal fiber-solution three-phase interface. Sampling analysis after the reaction showed that the oil content in the deoiled solution was 52.43 mg / L, indicating a low oil removal rate.

[0101] Comparative Example 4

[0102] This comparative example provides a process for steam deoiling of raffinate, which is the same as Example 1, except that: in step (3), the secondary condensed liquid is passed through titanium wire ball filter layers with a thickness of 150 mm and a thickness of 200 mm in sequence, and high-temperature steam and low-temperature air are not introduced into the two filter layers. After filtration, the secondary filtered liquid is obtained.

[0103] Then, 50g of porous activated carbon was added to the secondary filtered liquid and stirred for 2h for deep adsorption and removal of activated carbon. After solid-liquid separation, the activated carbon was returned for recycling. The filtrate obtained was the deoiled liquid with an oil content of 59.04mg / L.

[0104] Compared to Example 1, the solution in this comparative example did not undergo the corresponding high-temperature steam and low-temperature air when passing through the metal fiber filter layer. In other words, no gas-liquid-solid three-phase interface coalescing filtration was performed, and only liquid-solid two-phase filtration was involved. Sampling analysis after the reaction concluded that the oil content in the deoiled solution was 59.04 mg / L, indicating a low oil removal rate.

[0105] Comparative Example 5

[0106] This comparative example provides a process for steam deoiling of raffinate, which specifically comprises the following steps:

[0107] (1) 10 L of zinc extraction residual solution from the P204 extraction process in zinc smelting was taken, with an oil content of 140 mg / L. Steam at 150°C was introduced into the solution at high speed to perform high-temperature denaturation and demulsification of P204-kerosene particles and agglomeration and floating of microbubbles. The aeration time was 2 h, and continuous stirring was performed to enhance the agglomeration effect. After the aeration was completed, the oil phase suspended on the liquid surface was filtered and separated to obtain a first-stage agglomerated liquid.

[0108] (2) The first-stage coalesced liquid is passed into a titanium wire ball filter layer with a thickness of 150 mm. At the same time, steam at 150°C is slowly sprayed into the titanium wire ball filter layer for 40 minutes to perform thermal coalescing and floating at the steam-metal fiber-solution three-phase interface. The P204-kerosene particles coalesce and float under the action of steam. When passing through the metal fiber filter layer, the P204-kerosene particles adhere to the surface of the metal fiber to form oil-containing metal fibers and the first-stage filtered liquid.

[0109] (3) The first-stage filtered liquid is passed into a titanium wire spherical filter layer with a thickness of 200 mm, and at the same time, air at 5°C is slowly sprayed into the titanium wire spherical filter layer for 2 hours to perform rapid cooling, solidification and agglomeration of the low-temperature air-metal fiber-solution three-phase interface. The P204-kerosene particles are further precipitated and agglomerated under the action of the cold air, and are stably solidified and attached to the titanium wire spherical filter layer under the action of microbubbles to form oil-containing metal fibers and filtered liquid, i.e., the second-stage filtered liquid.

[0110] (4) Add 50 g of porous activated carbon to the secondary filtered liquid obtained in step (3), stir for 2 h, and perform deep adsorption removal of the activated carbon. After solid-liquid separation, the activated carbon is returned for recycling. The adsorbed liquid obtained is the deoiled liquid, and the oil content is 45.43 mg / L.

[0111] Compared with Example 1, this comparative example did not perform preheating flotation with medium-temperature circulating gas. After the reaction, sampling and analysis showed that the oil content in the deoiled liquid was 45.43 mg / L, indicating a low oil removal rate.

[0112] Comparative Example 6

[0113] This comparative example provides a process for steam deoiling of raffinate, which specifically comprises the following steps:

[0114] (1) 10 L of zinc extraction raffinate from the P204 extraction process in zinc smelting, with an oil content of 140 mg / L, was taken. Medium-temperature circulating gas at a temperature of 95°C was introduced into the solution. The raffinate was preheated and subjected to primary flotation and coalescence, and then filtered to obtain a primary coalescence liquid.

[0115] (2) The first-stage coalesced liquid is passed into a titanium wire ball filter layer with a thickness of 150 mm. At the same time, steam at 150°C is slowly sprayed into the titanium wire ball filter layer for 40 minutes to perform thermal coalescing and floating at the steam-metal fiber-solution three-phase interface. The P204-kerosene particles coalesce and float under the action of steam. When passing through the metal fiber filter layer, the P204-kerosene particles adhere to the surface of the metal fiber to form oil-containing metal fibers and the first-stage filtered liquid.

[0116] (3) The first-stage filtered liquid is passed into a titanium wire spherical filter layer with a thickness of 200 mm, and at the same time, air at 5°C is slowly sprayed into the titanium wire spherical filter layer for 2 hours to perform rapid cooling, solidification and agglomeration of the low-temperature air-metal fiber-solution three-phase interface. The P204-kerosene particles are further precipitated and agglomerated under the action of the cold air, and are stably solidified and attached to the titanium wire spherical filter layer under the action of microbubbles to form oil-containing metal fibers and filtered liquid, i.e., the second-stage filtered liquid.

[0117] (4) Add 50 g of porous activated carbon to the secondary filtered liquid obtained in step (3), stir for 2 h, and perform deep adsorption removal of the activated carbon. After solid-liquid separation, the activated carbon is returned for recycling. The adsorbed liquid obtained is the deoiled liquid, and the oil content is 61.85 mg / L.

[0118] Compared with Example 1, this comparative example did not perform high-temperature steam demulsification polymerization. After the reaction, sampling and analysis showed that the oil content in the deoiled liquid was 61.85 mg / L, indicating a low oil removal rate.

[0119] Comparative Example 7

[0120] This comparative example provides a process for steam deoiling of raffinate, which is the same as that of Example 1, except that after step (4), the secondary filtered liquid obtained is directly used as the deoiled liquid without activated carbon adsorption, wherein the oil content of the deoiled liquid is 25.82 mg / L.

[0121] Compared to Example 1, this comparative example did not perform activated carbon adsorption. Sampling and analysis after the reaction revealed an oil content of 25.82 mg / L in the deoiled liquid. Compared to the raw material, the oil content in the deoiled liquid was still higher, indicating a lower oil removal rate.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0123] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and to form different embodiments. For example, any of the above-described claimed embodiments may be used in any combination. The information disclosed in this background section is intended solely to enhance understanding of the overall background of this application and should not be construed as an admission or any form of implication that such information constitutes prior art known to those skilled in the art. Industrial Applicability

[0124] In summary, the present application provides a method for steam deoiling of raffinate, by using medium-temperature circulating gas for flotation and coalescence - high-temperature steam is used to modify, demulsify and inactivate the oil particles in the raffinate, and then through hot / cold two-stage coalescence and solidification filtration, the oil particles are floated and coalesced under the action of bubbles, and solidified and coalesced under the action of the fiber layer to achieve oil removal.

Claims

1. A method for steam deoiling of raffinate, characterized in that: include: S1: introducing medium-temperature circulating waste gas into the raffinate, separating and filtering to obtain the first-stage coalesced liquid; S2: passing high-temperature steam into the first-stage coalesced liquid to demulsify and inactivate the liquid, and then separating and filtering to obtain the second-stage coalesced liquid; S3: passing the secondary coalesced liquid through a first metal fiber filter layer into which high-temperature steam is passed and a second metal fiber filter layer into which low-temperature air is passed, performing two-stage filtration to obtain a secondary filtered liquid; S4: The secondary filtered liquid is subjected to activated carbon adsorption removal to obtain a deoiled liquid.

2. The method for deoiling raffinate by steam as claimed in claim 1, wherein: The temperature of the medium-temperature circulating exhaust gas is 45°C-115°C.

3. The method for deoiling raffinate by steam according to claim 1 or 2, wherein: The temperature of the high-temperature steam is 115°C-450°C.

4. The method for steam deoiling of raffinate according to any one of claims 1 to 3, wherein: The temperature of the low-temperature air is -25°C to 32°C.

5. The method for deoiling raffinate by steam according to any one of claims 1 to 4, characterized in that: The medium-temperature circulating waste gas comes from the secondary gas recovered from S2 and S3.

6. The method for steam deoiling of raffinate according to any one of claims 1 to 5, wherein: The material of the first metal fiber filter layer and the second metal fiber filter layer includes at least one of titanium and stainless steel; And / or, the metal fibers in the first metal fiber filter layer and the second metal fiber filter layer are each independently in a felt shape or formed by stacking small balls; And / or, the high-temperature steam is introduced from the bottom of the first metal fiber filter layer from bottom to top, and the low-temperature air is introduced from the bottom of the second metal fiber filter layer from bottom to top.

7. The method for steam deoiling of raffinate according to any one of claims 1 to 6, wherein: The introduction rate of high-temperature steam in S2 is higher than the introduction rate of high-temperature steam in the first metal fiber filter layer in S3.

8. The method for deoiling raffinate by steam according to any one of claims 1 to 7, wherein: When the secondary coalesced liquid flows through the first metal fiber filter layer and the second metal fiber filter layer in sequence, the oil particles in the secondary coalesced liquid undergo hot interface coalescence at the gas-liquid-solid interface of the first metal fiber filter layer and undergo sudden cooling and solidification coalescence at the gas-liquid-solid interface of the second metal fiber filter layer. After the two-stage filtration, the oil particles adhere to the surface of the first metal fiber filter layer and the surface of the second metal fiber filter layer, respectively, to form oil-containing metal fibers.

9. The method for deoiling raffinate by steam as claimed in claim 8, wherein: The oil-containing metal fiber is regenerated into oil-free metal fiber by high-temperature thermal decomposition, and the temperature of the high-temperature thermal decomposition is 230°C-850°C.

10. The method for deoiling raffinate by steam according to any one of claims 1 to 9, characterized in that: The thickness of the first metal fiber filter layer and the second metal fiber filter layer are independently 100 mm to 250 mm.

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