Method for recovering oil content in lithium extraction raffinate

Abstract

The invention discloses a method for recovering oil in lithium extraction raffinate, and relates to the technical field of waste recovery. Demulsification is realized by adjusting the pH value of the oil-containing raffinate to be acidic, so that more oil is enriched on the surface of the water phase A, the oil can be sufficiently and quickly enriched on the upper layer or the surface of the water phase B through aeration treatment, and the upper-layer water phase of the water phase B is taken for extraction separation, so that the oil can be enriched in a second organic phase to be recycled. By adopting the method provided by the invention, the oil removal rate is very high, the treatment cost of the raffinate as industrial wastewater can be reduced, and the loss of the extracting agent is also reduced, so that the economic benefit is increased.

Description

Technical Field

[0001] The invention relates to the technical field of waste material recovery, and in particular to a method for recovering oil from lithium extraction raffinate. Background Art

[0002] In the process of extracting metals from the aqueous phase, the organic phase contacts the aqueous phase and extracts the metals from the aqueous phase into the organic phase. At the same time, the organic phase also enters the aqueous phase to form an oily raffinate. The oily raffinate is a common industrial wastewater that is difficult to degrade. When it enters the environment, it will cause serious pollution to plants, soil, water bodies, etc. In addition, the price of the extractant in the oily raffinate of lithium extraction is relatively expensive. If it can be recycled, it can not only reduce the consumption of lithium extractant, but also reduce the degradation cost of treating such industrial wastewater.

[0003] At present, the industry mainly uses ultrasonic method, flotation method, fiber ball and activated carbon adsorption and other oil removal methods for extract liquid to reduce the oil in the extract liquid to industrial emission standards. However, no matter which method is used, the fixed oil needs to be further degraded and treated, and these traditional methods require high industrial costs. There is currently no effective way to recycle and reuse these oils.

[0004] Therefore, there is an urgent need to develop a new raffinate treatment process to recover the oil in the lithium extraction raffinate and reuse it while reducing industrial costs.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a method for recovering oil from lithium extraction raffinate, aiming to efficiently recover the oil from lithium extraction raffinate while reducing industrial costs.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides a method for recovering oil from lithium extraction raffinate, comprising:

[0009] Adjusting the pH value of the oil-containing raffinate to acidic to obtain aqueous phase A;

[0010] Aeration treatment is performed on the aqueous phase A to obtain aqueous phase B;

[0011] The upper aqueous phase of aqueous phase B is mixed with the first organic phase, and separated by extraction to obtain a second organic phase and aqueous phase C.

[0012] In an optional embodiment, the pH value of the oil-containing raffinate is adjusted to 1-4, preferably 2-3, using a mineral acid.

[0013] In an optional embodiment, the inorganic acid is selected from at least one of sulfuric acid and hydrochloric acid.

[0014] In an optional embodiment, a nano bubble disk is used to aerate the aqueous phase A, and the ventilation volume is controlled to be 0.5m 3 / h-6.0m 3 / h, aeration time is 0.5h-6.0h;

[0015] Preferably, the ventilation volume is controlled to be 2.0 m 3 / h-3.0m 3 / h, aeration time is 1h-3h.

[0016] In an optional embodiment, the second organic phase and the aqueous phase C are prepared by multi-stage countercurrent extraction and phase separation;

[0017] Preferably, the number of extraction stages is 2-10.

[0018] In an optional embodiment, in the process of obtaining the second organic phase and the aqueous phase C, the extraction phase ratio O / A is controlled to be 1:(0.3-3.0), preferably 1:(0.5-2.0).

[0019] In an optional embodiment, the extraction temperature is controlled to be 20°C-70°C, and the single-stage extraction time is 0.05h-0.50h;

[0020] Preferably, the rotation speed during the extraction process is 150 rpm-450 rpm.

[0021] In an optional embodiment, the ratio of the volume of the upper aqueous phase of aqueous phase B to the total volume of aqueous phase B is 1:(2-20).

[0022] In an optional embodiment, the first organic phase contains a diluent, and the diluent is selected from alkanes;

[0023] Preferably, the first organic phase further contains at least one of an extractant and a phase modifier; the extractant is selected from at least one of LiSX and HBL121; the phase modifier is selected from at least one of isooctyl alcohol and trioctylphosphine oxide.

[0024] In an optional embodiment, the method further comprises: mixing the aqueous phase C with the aqueous phase A of the next stage and subjecting the mixture to aeration treatment to obtain the aqueous phase B of the next stage;

[0025] The upper aqueous phase of the aqueous phase B of the next stage is mixed with the second organic phase, and separated by extraction to obtain the second organic phase and aqueous phase C of the next stage;

[0026] The aqueous phase C and the second organic phase are circulated to perform the above steps until the oil content in the obtained second organic phase no longer increases, and then a new first organic phase is replaced to enter the cycle, and the finally obtained second organic phase is sent to the lithium extraction section for recycling.

[0027] The present invention has the following beneficial effects: demulsification is achieved by adjusting the pH value of the oil-containing raffinate to acidity, so that the oil is more enriched on the surface of the water phase A, and the oil can be fully and quickly enriched to the upper layer or surface of the water phase B through aeration treatment, and the upper water phase of the water phase B is extracted and separated, so that the oil can be enriched in the second organic phase for recovery. The method provided by the present invention has a high oil removal rate, which can reduce the treatment cost of the raffinate as industrial wastewater, and also reduce the loss of the extractant, thereby increasing economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A process flow chart for recovering oil from lithium extraction raffinate provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0031] The extractant in the oil-containing extract obtained after lithium extraction is relatively expensive. The present invention effectively recovers this part of oil through a unique recovery process, which can significantly reduce industrial processing costs and improve economic benefits.

[0032] The present invention provides a method for recovering oil from lithium extraction raffinate. Figure 1 , the steps are as follows:

[0033] S1. Adjust pH

[0034] The oil content in the lithium extraction raffinate is initially evenly distributed. By adjusting the pH value of the oil-containing raffinate to acidic, the oil content is concentrated more on the surface through demulsification to obtain the aqueous phase A.

[0035] Specifically, the lithium extraction raffinate (i.e., oily raffinate) comes from the oily wastewater generated during the metal recovery process of the ternary battery powder. The metal recovery process of the ternary battery powder can refer to the existing technology, where the lithium-containing solution is mixed with the organic phase to extract lithium, the lithium enters the organic phase, and the obtained aqueous phase is the raffinate.

[0036] In some embodiments, the pH value of the oil-containing raffinate is adjusted to 1-4, preferably 2-3, by using an inorganic acid. Within this pH range, the oil can be better enriched on the surface of the water phase. Specifically, the pH value of the obtained water phase A can be 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, etc.

[0037] In some embodiments, the inorganic acid is selected from at least one of sulfuric acid and hydrochloric acid. The inorganic acid can be any one or more of the above. The raw materials of the above inorganic acids are easily available and have low cost.

[0038] S2. Aeration

[0039] The water phase A is aerated to allow the oil to be fully enriched in the upper layer or surface of the water phase to obtain the water phase B.

[0040] In some embodiments, a nano bubble disk can be used to aerate the aqueous phase A. The nano bubble disk generates bubbles with a diameter of nanometers through a microporous structure. These bubbles have the characteristics of high specific surface area, long residence time, high dissolution efficiency, etc., and can enrich the oil in the aqueous phase A. Specifically, the nano bubble disk is a commercially available device with a pore diameter of less than 50 microns. The bubble disk is generally made of steel sand, and can produce nanometer-level bubbles by squeezing air and cutting the gas.

[0041] Furthermore, when the nano bubble disk is used to aerate the water phase A, the ventilation volume is controlled to be 0.5m 3 / h-6.0m 3 / h, such as 0.5m 3 / h、1.0m 3 / h、2.0m 3 / h、3.0m 3 / h、4.0m 3 / h、5.0m 3 / h、6.0m 3 / h, etc.; the aeration time is 0.5h-6.0h, such as 0.5h, 1.0h, 2.0h, 3.0h, 4.0h, 5.0h, 6.0h, etc. In a preferred embodiment, the ventilation volume is controlled to be 2.0m 3 / h-3.0m 3 / h, and the aeration time is 1h-3h. By adjusting the ventilation volume and aeration time within the optimal range, it is beneficial to reduce the process energy consumption while ensuring the oil enrichment effect.

[0042] S3. Extraction

[0043] The upper aqueous phase of aqueous phase B is mixed with the first organic phase, and subjected to extraction and separation, so that the oil content enters the organic phase, thereby obtaining a second organic phase loaded with oil content and aqueous phase C.

[0044] In some embodiments, multi-stage countercurrent extraction and phase separation are performed at a certain reaction temperature, rotation speed and time to obtain the second organic phase and aqueous phase C. The number of extraction stages can be 2-10, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0045] Furthermore, in the process of obtaining the second organic phase and the aqueous phase C, the extraction phase ratio O / A is controlled to be 1:(0.3-3.0), such as 1:0.3, 1:0.5, 1:1.0, 1:2.0, 1:3.0, etc., preferably 1:(0.5-2.0). The extraction phase ratio O / A refers to the volume ratio of the organic phase to the aqueous phase. The extraction phase ratio O / A is controlled within the above range for each stage of extraction to improve the extraction effect of the oil.

[0046] Further, during the extraction process, the extraction temperature is controlled to be 20°C-70°C, the single-stage extraction time is 0.05h-0.50h, and the rotation speed is 150rpm-450rpm. It is appropriate to control the extraction temperature, time and rotation speed within the above range, and the extraction conditions of each stage can be consistent, so that the oil is better enriched in the second organic phase. Specifically, the extraction temperature can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, etc., the single-stage extraction time can be 0.05h, 0.10h, 0.20h, 0.30h, 0.40h, 0.50h, etc., and the rotation speed can be 150rpm, 200rpm, 250rpm, 300rpm, 350rpm, 400rpm, 450rpm, etc.

[0047] In some embodiments, the ratio of the volume of the upper aqueous phase of aqueous phase B to the total volume of aqueous phase B is 1:(2-20), such as 1:2, 1:5, 1:8, 1:10, 1:13, 1:15, 1:18, 1:20, etc. It is advisable to operate according to the above ratio when taking the upper aqueous phase of aqueous phase B, so that the oil can be fully recovered.

[0048] In some embodiments, the first organic phase contains a diluent, which can be a single-component diluent selected from alkanes, such as 260# kerosene.

[0049] In another embodiment, the first organic phase further contains at least one of an extractant and a phase modifier, that is, the first organic phase can be a combination of a diluent and an extractant, a combination of a diluent and a phase modifier, or a combination of a diluent, an extractant and a phase modifier. Among them, the extractant is selected from at least one of LiSX and HBL121, and the extractant can be any one or more of the above, and LiSX and HBL121 are both commercially available raw materials. The phase modifier is selected from at least one of isooctyl alcohol and trioctylphosphine oxide, and the phase modifier can be any one or more of the above.

[0050] It should be noted that the components of the first organic phase used in the whole process are one or more of the organic phase components of the lithium extraction stage, so the organic phase can be recycled multiple times, and the whole process is simple to operate and easy to industrialize.

[0051] S4. Loop

[0052] After obtaining the aqueous phase C and the second organic phase in step S3, the two phases can be recycled. The specific steps are as follows:

[0053] The aqueous phase C is mixed with the aqueous phase A of the next stage for aeration treatment to obtain the aqueous phase B of the next stage; the upper aqueous phase of the aqueous phase B of the next stage is mixed with the second organic phase, extracted and separated to obtain the second organic phase and the aqueous phase C of the next stage; by continuously circulating the aqueous phase C and the second organic phase, the oil content in the obtained second organic phase no longer increases (that is, when it cannot absorb more oil), the fresh first organic phase is replaced to enter the circulation, and the finally obtained second organic phase is re-entered into the lithium extraction section for recycling by adding an extractant or a diluent.

[0054] During the circulation process, the parameter control of aeration treatment is the same as that of step S2; the extraction ratio, temperature, rotation speed, reaction time and extraction stage are the same as those of step S3.

[0055] It should be noted that through steps S1-S4, the expensive oil in the raffinate can be recovered and recycled. The pH of the raffinate is first adjusted to acidic by inorganic acid to enrich the oil in the aqueous phase, and then the oil in the water is enriched to the upper layer or surface of the aqueous phase by small air bubbles, and then the second organic phase and aqueous phase C loaded with oil are obtained by multi-stage countercurrent extraction. The method provided by the present invention has a high oil removal rate, which can reduce the treatment cost of the raffinate as industrial wastewater, and also reduce the loss of the extractant, thereby increasing economic benefits. In addition, when the second organic phase cannot absorb more oil, the second organic phase can be reused by adding other components required by the organic phase of the lithium extraction section into the lithium extraction section.

[0056] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0057] It should be noted that the lithium extraction raffinate treated in the following examples and comparative examples is derived from the oily wastewater generated during the metal recovery process of ternary battery powder. The specific process is as follows: (1) Leaching: Waste ternary battery powder is leached using sulfuric acid and hydrogen peroxide to obtain a solution containing nickel, cobalt, manganese, lithium, copper, aluminum, calcium and magnesium. (2) Impurity removal: First use iron powder, followed by sodium carbonate and sodium fluoride to remove copper, aluminum, calcium and magnesium in the solution as well as the introduced iron; (3) Extraction of nickel, cobalt and manganese: Use the extractant P507 to extract the nickel, cobalt and manganese in the solution. At this time, there are still lithium and sodium in the solution, as well as a little nickel, cobalt, manganese and calcium and magnesium remaining in the solution in the two steps of extracting nickel, cobalt and manganese and removing calcium and magnesium. After the previous steps (1)-(3), the components in the solution are the components before extraction; (4) Extraction of lithium: Use lithium extractant LiSX or HB121 to extract the lithium in the solution to obtain a raffinate containing a large amount of sodium.

[0058] Due to different processing parameters, the compositions of the raffinate treated in the following examples and comparative examples are slightly different, but the main components are as follows: Li: 2.6-4.3 g / L, Na: 40-46 g / L, Ni+Co+Mn about 0.1 g / L, Mg 0.05 g / L, COD content of 1000-2000 mg / L, and oil content of about 50-100 mg / L.

[0059] Example 1

[0060] This embodiment provides a method for recovering oil from lithium extraction raffinate, the steps are as follows:

[0061] (1) Adjusting the pH: Using sulfuric acid (mass fraction 98%), the pH of 1 L of the raffinate is adjusted to 3 to obtain an aqueous phase A.

[0062] (2) Aeration treatment, using a ventilation volume of 2m 3 / h nano bubble disk was used to aerate water phase A for 3 h to obtain water phase B.

[0063] (3) Extraction, using 260# solvent oil (i.e., 260# kerosene) as the first organic phase to perform three-stage countercurrent mixing with the upper aqueous phase B, the extraction phase ratio O / A=1:1, the single-stage extraction time is 5 min, the extraction temperature is 25°C, the mixing speed is 300 rpm, and the second organic phase and aqueous phase C are obtained. The upper aqueous phase B, i.e., the upper layer of aqueous phase B, has a volume ratio of 1:3 to the total volume of aqueous phase B.

[0064] (4) Circulation, mixing the aqueous phase C with the aqueous phase A of the next stage and subjecting it to aeration treatment to obtain a new aqueous phase B, and if the second organic phase is not saturated, it is mixed with the new upper aqueous phase B as the first organic phase, and if the second organic phase is saturated, it enters the lithium extraction section after treatment. The parameters of aeration treatment and extraction refer to steps (2) and (3).

[0065] Example 2

[0066] This embodiment provides a method for recovering oil from lithium extraction raffinate, the steps are as follows:

[0067] (1) Adjusting the pH: Using sulfuric acid (mass fraction 98%), the pH of 1 L of the raffinate is adjusted to 2 to obtain an aqueous phase A.

[0068] (2) Aeration treatment, using a ventilation volume of 3m 3 / h nano bubble disk was used to aerate water phase A for 6 h to obtain water phase B.

[0069] (3) Mixing: using 260# solvent oil as the first organic phase to perform three-stage countercurrent mixing on the upper aqueous phase B, the extraction phase ratio O / A=1:1, the single-stage extraction time is 5 min, the extraction temperature is 25°C, and the mixing speed is 300 rpm to obtain a second organic phase and an aqueous phase C. The upper aqueous phase B, i.e., the upper layer of the aqueous phase B, has a volume ratio of 1:5 to the total volume of the aqueous phase B.

[0070] (4) Circulation, mixing the aqueous phase C with the aqueous phase A of the next stage and subjecting it to aeration treatment to obtain a new aqueous phase B, and if the second organic phase is not saturated, it is mixed with the new upper aqueous phase B as the first organic phase, and if the second organic phase is saturated, it enters the lithium extraction section after treatment. The parameters of aeration treatment and extraction refer to steps (2) and (3).

[0071] Example 3

[0072] This embodiment provides a method for recovering oil from lithium extraction raffinate, the steps are as follows:

[0073] (1) Adjusting the pH: Using sulfuric acid (mass fraction 98%), the pH of 1 L of the raffinate is adjusted to 3 to obtain an aqueous phase A.

[0074] (2) Aeration treatment, using a ventilation volume of 2m 3 / h nano bubble disk was used to aerate water phase A for 3 h to obtain water phase B.

[0075] (3) Mixing: using a mixture of 260# solvent oil and 10% lithium extractant (the lithium extractant is LiSX, and the volume ratio of the lithium extractant to 260# solvent oil is 1:9) as the first organic phase to perform three-stage countercurrent mixing on the upper aqueous phase B, the extraction phase ratio O / A=2:1, the single-stage extraction time is 10 min, the extraction temperature is 55°C, and the mixing speed is 350 rpm to obtain a second organic phase and an aqueous phase C. The upper aqueous phase B, i.e., the upper layer of the aqueous phase B, has a volume ratio of 1:2 to the total volume of the aqueous phase B.

[0076] (4) Circulation, mixing the aqueous phase C with the aqueous phase A of the next stage and subjecting it to aeration treatment to obtain a new aqueous phase B, and if the second organic phase is not saturated, it is mixed with the new upper aqueous phase B as the first organic phase, and if the second organic phase is saturated, it enters the lithium extraction section after treatment. The parameters of aeration treatment and extraction refer to steps (2) and (3).

[0077] Example 4

[0078] This embodiment provides a method for recovering oil from lithium extraction raffinate, the steps are as follows:

[0079] (1) Adjusting the pH: Using sulfuric acid (mass fraction 98%), the pH of 1 L of the raffinate is adjusted to 2 to obtain an aqueous phase A.

[0080] (2) Aeration treatment, using a ventilation volume of 3m 3 / h nano bubble disk was used to aerate water phase A for 6 h to obtain water phase B.

[0081] (3) Mixing: using 260# solvent oil and 5% modifier (trioctylphosphine oxide, the volume ratio of modifier to 260# solvent oil is 5:95) as the first organic phase to perform three-stage countercurrent mixing on the upper aqueous phase B, the extraction phase O / A = 2:1, the single-stage extraction time is 10 min, the mixing temperature is 55°C, the mixing speed is 350 rpm, and the second organic phase and aqueous phase C are obtained. The upper aqueous phase B is the upper layer of aqueous phase B, and the ratio of the volume of the upper aqueous phase B to the total volume of aqueous phase B is 1:2.

[0082] (4) Circulation, mixing the aqueous phase C with the aqueous phase A of the next stage and subjecting it to aeration treatment to obtain a new aqueous phase B, and if the second organic phase is not saturated, it is mixed with the new upper aqueous phase B as the first organic phase, and if the second organic phase is saturated, it enters the lithium extraction section after treatment. The parameters of aeration treatment and extraction refer to steps (2) and (3).

[0083] Example 5

[0084] This embodiment provides a method for recovering oil from lithium extraction raffinate, the steps are as follows:

[0085] (1) Adjusting the pH: Using sulfuric acid (mass fraction 98%), the pH of 1 L of the raffinate is adjusted to 4 to obtain an aqueous phase A.

[0086] (2) Aeration treatment, using a ventilation volume of 4m 3 / h nano bubble disk was used to aerate water phase A for 6 h to obtain water phase B.

[0087] (3) Mixing: 260# solvent oil, 10% lithium extractant (LiSX, with a volume ratio of 10:85 to 260# solvent oil) and 5% modifier (trioctylphosphine oxide, with a volume ratio of 5:85 to 260# solvent oil) were used as the first organic phase to perform three-stage countercurrent mixing on the upper aqueous phase B, with an extraction phase ratio O / A=1:2, a single-stage extraction time of 20 min, a mixing temperature of 35° C., and a mixing speed of 250 rpm to obtain a second organic phase and an aqueous phase C. The upper aqueous phase B, i.e., the upper layer of aqueous phase B, has a volume ratio of 1:10 to the total volume of aqueous phase B.

[0088] (4) Circulation, mixing the aqueous phase C with the aqueous phase A of the next stage and subjecting it to aeration treatment to obtain a new aqueous phase B, and if the second organic phase is not saturated, it is used as the first organic phase to extract with the new upper aqueous phase B, and if the second organic phase is saturated, it enters the lithium extraction section after treatment. The parameters of aeration treatment and extraction refer to steps (2) and (3).

[0089] Example 6

[0090] The only difference from Example 1 is that the pH value is adjusted to 0.5 in step (1).

[0091] Example 7

[0092] The only difference from Example 1 is that the pH value is adjusted to 1.0 in step (1).

[0093] Example 8

[0094] The only difference from Example 1 is that the pH value is adjusted to 2.0 in step (1).

[0095] Example 9

[0096] The only difference from Example 1 is that the pH value is adjusted to 4.0 in step (1).

[0097] Example 10

[0098] The only difference from Example 1 is that the pH value is adjusted to 5.0 in step (1).

[0099] Embodiment 11

[0100] The only difference from Example 1 is that the aeration rate in step (2) is 0.1 m 3 / h.

[0101] Comparative Example 1

[0102] The only difference from Example 1 is that step (2) uses centrifugation instead of aeration treatment. The specific operation is as follows: the above aqueous phase is placed in a centrifuge for centrifugation for 1 hour at a centrifugal speed of 10,000 rpm to obtain aqueous phase B.

[0103] Comparative Example 2

[0104] The only difference from Example 1 is that in step (2), aggregation resin is used instead of aeration treatment. The specific operation is as follows: the above aqueous phase is passed through aggregation resin to obtain aqueous phase B, with a flow rate of 1 BV / h.

[0105] It should be noted that the oil-aggregating resin mainly uses the lipophilic and hydrophobic properties of the resin to separate emulsified oil molecules and dissolved oil molecules from water, and to "break the emulsion", "capture" and "enrich" the oil molecules in the condensed water on the resin surface in time. When the oil molecules adsorbed on the resin reach a certain level, the enriched oil is automatically separated in the form of large oil droplets under the impact of the water flow, and the separated large oil droplets exist on the surface of the water phase.

[0106] Among them, many types of aggregation resins have been tried, such as: provided by Shanghai Sean Technology Co., Ltd., code-named CNO; provided by Ningbo Zhengguang Resin Co., Ltd., code-named SO107; provided by Purolite (China), code-named OL100. The treatment effect of aggregation resins is not ideal. The data in Table 1 are the test results of CNO, and the effects of other resins are similar to CNO.

[0107] Comparative Example 3

[0108] The only difference from Example 1 is that step (1) is not performed.

[0109] Test example

[0110] The degreasing effects of the methods of the embodiments and comparative examples were tested, and the results are shown in Table 1.

[0111] Table 1 Comparison of oil removal effects of the methods of the embodiments and comparative examples

[0112]

[0113]

[0114] The treated raffinate in Table 1 is the wastewater discharged from the system after circulation. Figure 1 The oil recovery rate is the recovery rate calculated after ignoring the volume of the upper aqueous phase B.

[0115] It can be seen from Table 1 that, compared with the comparative example, the method provided in the embodiment of the present invention can significantly improve the recovery rate of oil.

[0116] By comparing Example 1 with Examples 6-10, it can be seen that the preferred pH value when adjusting the pH value is 2-3.

[0117] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recovering oil from lithium extraction raffinate, characterized in that: include: Adjusting the pH value of the oil-containing raffinate to acidic to obtain aqueous phase A; aerating the aqueous phase A to obtain an aqueous phase B; The upper aqueous phase of the aqueous phase B is mixed with the first organic phase, and separated by extraction to obtain a second organic phase and an aqueous phase C.

2. The method according to claim 1, characterized in that: The pH value of the oil-containing raffinate is adjusted to 1-4, preferably 2-3, using an inorganic acid.

3. The method according to claim 2, characterized in that The inorganic acid is selected from at least one of sulfuric acid and hydrochloric acid.

4. The method according to claim 1, characterized in that: The water phase A was aerated using a nano bubble disk, and the ventilation volume was controlled to be 0.5m 3 / h-6.0m 3 / h, aeration time is 0.5h-6.0h; Preferably, the ventilation volume is controlled to be 2.0 m 3 / h-3.0m 3 / h, aeration time is 1h-3h.

5. The method according to claim 1, characterized in that The second organic phase and the aqueous phase C are prepared by multi-stage countercurrent extraction and phase separation; Preferably, the number of extraction stages is 2-10.

6. The method according to claim 1 or 5, characterized in that: In the process of obtaining the second organic phase and aqueous phase C, the extraction phase ratio O / A is controlled to be 1:(0.3-3.0), preferably 1:(0.5-2.0).

7. The method according to claim 1 or 5, characterized in that: The extraction temperature is controlled at 20℃-70℃, and the single-stage extraction time is 0.05h-0.50h; Preferably, the rotation speed during the extraction process is 150 rpm-450 rpm.

8. The method according to claim 1, characterized in that The ratio of the volume of the upper aqueous phase of the aqueous phase B to the total volume of the aqueous phase B is 1:(2-20).

9. The method according to claim 1, characterized in that: The first organic phase contains a diluent, and the diluent is selected from alkanes; Preferably, the first organic phase further contains at least one of an extractant and a phase modifier; the extractant is selected from at least one of LiSX and HBL121; the phase modifier is selected from at least one of isooctyl alcohol and trioctylphosphine oxide.

10. The method according to claim 1, characterized in that Also includes: The aqueous phase C is mixed with the aqueous phase A of the next stage to undergo the aeration treatment to obtain the aqueous phase B of the next stage; The upper aqueous phase of the aqueous phase B of the next stage is mixed with the second organic phase, and separated by extraction to obtain the second organic phase and aqueous phase C of the next stage; The aqueous phase C and the second organic phase are circulated to carry out the above steps until the oil content in the obtained second organic phase no longer increases, then the new first organic phase is replaced to enter the cycle, and the finally obtained second organic phase is sent to the lithium extraction section for recycling.

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