Titanium-containing waste liquid treatment method

Abstract

The invention discloses a titanium-containing waste liquid treatment method, which comprises: carrying out rectification on a titanium-containing waste liquid in a rectification tower, and controlling the normal pressure boiling point to be less than 135 DEG C, and discharging the low boiling point fraction from the tower top; continuously rectifying the materials in the tower kettle of the rectifying tower, separating out a titanium tetrachloride material from the tower top, and separating out rectifying residual liquid from the tower bottom; at the temperature of less than 60 DEG C, washing the rectification residual liquid with washing liquid, and performing phase separation to obtain an oil phase and a water phase; dehydrating the oil phase, partially circulating or completely circulating into the rectifying tower, mixing with fresh titanium-containing waste liquid, and rectifying again; the washing liquid is selected from water, an aqueous phase or an alkaline aqueous solution. According to the method, high-boiling-point organic matter existing in a catalyst preparation system is used as an inert solvent, a third component does not need to be additionally added, after low-boiling-point fractions, titanium tetrachloride and other target objects are sequentially separated out through rectification, rectification kettle liquid is washed through washing liquid, solid matter, titanate and other impurities are thoroughly removed, and the purity of the product is improved. And the washed solvent is recycled or directly reused after being subjected to dehydration treatment.

Description

Technical Field

[0001] The invention relates to the field of industrial waste liquid treatment, and in particular to a method for treating titanium-containing waste liquid. Background Art

[0002] In the industrial production of polyolefins, Ziegler-Natta catalysts have the characteristics of high catalytic efficiency and good polymer performance, and are the main force in the polyolefin catalyst market at present and in the foreseeable future. In the process of industrial preparation of Ziegler-Natta catalysts, magnesium chloride carriers react with excess titanium tetrachloride to carry out titanium-carrying reaction. After the solid catalyst is separated, a large amount of mother liquor and washing liquid rich in titanium tetrachloride, electron donors, alkoxides, hexane, toluene and other compounds will be produced. The mother liquor and washing liquid contain a large amount of unreacted titanium tetrachloride, low-boiling components (such as hexane), and a certain amount of high-boiling substances (such as alkoxy titanium), which are called titanium-containing waste liquid. Depending on the production process and catalyst products, there are certain differences in the corresponding components of the titanium-containing waste liquid.

[0003] At present, the treatment method of the titanium-containing waste liquid is mainly direct distillation. Generally, the organic solvent (such as toluene and hexane) and titanium tetrachloride are recovered by ordinary normal (reduced) pressure distillation, that is, the organic solvent and titanium tetrachloride are separated by distillation. In the process of normal (reduced) pressure distillation, high-boiling substances in the waste liquid are prone to coking and fouling, causing blockage of the bottom of the distillation tower, the reboiler and the internal components of the tower. The side reactions of the materials during the distillation process may also produce a large amount of volatile compounds and some unknown complex complexes, affecting the processing capacity of the recovery device and the continuity of its production, and causing the quality of the recovered titanium tetrachloride and hexane to be unstable. In order to ensure smooth discharge of the distillation tower kettle, it is usually necessary to maintain a high kettle residual liquid level in actual distillation production to maintain the fluidity of the kettle liquid and the dissolution and retention of the coking components, avoid and alleviate the influence of the coking components and the precipitation components, but this not only reduces the recovery rate of titanium tetrachloride, but also increases the amount of materials and the difficulty of handling in subsequent hazardous waste treatment.

[0004] In response to the above problems, the journal article "Pilot Study on Freezing Treatment of Polypropylene Spherical Catalyst Mother Liquor" started from the mother liquor distillation process, which is the largest titanium tetrachloride consumption link in the catalyst production process. Through research and analysis and organizing a series of small and pilot tests, the operating parameters and economic and technical indicators were optimized, and finally a new mother liquor treatment process route of cooling the mother liquor, washing and drying the precipitated solids, and further distilling the cooling liquid to recover titanium tetrachloride was determined, and the capacity was expanded and applied on the device. The effective implementation of the mother liquor cooling and impurity removal process avoids the risk of coking and scaling of the bottom concentrate caused by the original high-temperature distillation technology, extends the equipment life cycle, and improves the operation time of the device. After the device industrially applied this technology, the unit consumption of titanium tetrachloride per ton of product decreased significantly. At the same time, the frozen precipitate produced under the optimal conditions can be used as a resource without hydrolysis treatment, reducing the impact on the environment. At the same time, it greatly reduces the environmental protection management cost of the enterprise's waste acid generated by hydrolysis, and produces higher economic and social benefits. However, this technology attempts to avoid the risk of coking and scaling of the bottom concentrate caused by high-temperature distillation technology and extend the service life of the equipment by pre-treating the feed liquid through freeze precipitation. However, in actual applications, due to the influence of the catalyst mother liquor components, there is a problem of insufficient precipitation of slag-forming components or even difficulty in precipitation.

[0005] Chinese patent document CN113636592B discloses a resource processing equipment for polyolefin catalyst mother liquor, including a distillation tower, a first rectifying tower, a second rectifying tower and a third rectifying tower, and also includes an extraction kettle. The resource processing equipment for polyolefin catalyst mother liquor is used to process the polyolefin catalyst mother liquor, which can not only improve the recovery rate of titanium tetrachloride, but also solve the many deficiencies caused by the hydrolysis of high-boiling substances in the prior art, and is conducive to industrialization. However, the method uses an integrated method of rectification and extraction to process the titanium tetrachloride mother liquor, which not only requires the light organic solvent obtained by rectification to be remixed with the heavy component, resulting in problems such as increased energy consumption, but also cannot effectively solve the accumulation of high-boiling impurities such as soluble titanate removed in the system.

[0006] Chinese patent document CN113636589A discloses a resource treatment method for a polyolefin catalyst mother liquor, the polyolefin catalyst mother liquor contains titanium tetrachloride, an organic solvent I and chloroalkoxy titanium and / or an ester titanium complex, the method comprising: 1) cooling the polyolefin catalyst mother liquor and then performing solid-liquid separation to obtain a liquid phase I and a solid phase I; 2) distilling the liquid phase I obtained in step 1) to obtain a light component and a heavy component; 3) using the heavy component obtained in step 2) as an extraction raw material, extracting and separating the extraction raw material with an organic solvent II to obtain a liquid phase II and a solid phase II. According to the method of the present invention, the recovery rate of titanium tetrachloride can be improved, and the polyolefin catalyst mother liquor can be completely turned into treasure, thereby achieving the goal of resource treatment of waste liquid. However, the method uses an integrated method of freeze precipitation pretreatment + distillation and extraction to treat the titanium tetrachloride mother liquor, and there are problems such as insufficient removal of high-boiling impurities and inability to precipitate impurities with large solubility such as titanate.

[0007] Chinese patent document CN105566028B discloses a separation system and separation method for a polyolefin catalyst mother liquor. The separation system includes: a refrigeration device and a solid-liquid separation device are arranged before the first fractionation tower. The method includes: freezing and centrifuging the high-boiling product crystals of the mother liquor before entering the distillation tower for separation, and then entering the distillation tower system. The problems of tower blockage and long-cycle operation are solved, and the energy consumption of the device is reduced by combining the process flow and the heat exchange network, and finally a high-purity hydrocarbon solvent and high-purity titanium tetrachloride are obtained. However, the method uses a freeze precipitation pretreatment and a distillation method to treat the titanium tetrachloride mother liquor, and there are also problems such as insufficient removal of high-boiling impurities and inability to precipitate impurities with high solubility such as titanates.

[0008] Chinese patent document CN101717113B discloses a recovery and purification method for preparing titanium tetrachloride for olefin polymerization catalyst: the titanium tetrachloride mother liquor produced in the preparation process of olefin polymerization catalyst is added to the intermediate storage tank I, the circulating water of 10 ℃ to 30 ℃ is passed into the water jacket, and the stirring speed is 100 to 300 rpm; the pretreated titanium tetrachloride mother liquor is transferred to the deep cold kettle, the refrigerant medium of -5 ℃ to -35 ℃ is passed into the refrigerant jacket, the temperature of the titanium tetrachloride mother liquor is gradually reduced to between 0 ℃ and -25 ℃, the stirring speed is controlled to 10 to 150 rpm, and the cold precipitation is stirred for 2 to 12 hours; after the cold precipitation is completed, the supernatant and the crystals in the titanium tetrachloride mother liquor are separated, and the supernatant is transferred to the intermediate storage tank II through a pipeline. The method is simple in process, reduces energy consumption, has a high recovery rate, and is environmentally friendly. However, the method uses a freeze precipitation method to treat titanium tetrachloride mother liquor, which also has the problems of insufficient removal of high-boiling impurities and inability to precipitate impurities with high solubility such as titanate.

[0009] Chinese patent document CN112704894A discloses a catalyst solvent recovery method and titanium-containing solid, comprising the following steps: (1) sending a catalyst mother liquor containing titanium tetrachloride into a mother liquor coarse separation tower, obtaining a crude solvent at the top of the tower, and obtaining a first tower bottom logistics at the bottom of the tower; (2) the crude solvent enters a hydrocarbon solvent rectification tower, obtaining a first recovery solvent at the top of the tower, and obtaining a second tower bottom logistics at the bottom of the tower; (3) the first tower bottom logistics enters a titanium tetrachloride rectification tower, obtaining a titanium tetrachloride product at the top of the tower, and obtaining a third tower bottom logistics at the bottom of the tower; (4) mixing the second tower bottom logistics and the third tower bottom logistics to obtain a titanium tetrachloride-containing slurry; (5) the titanium tetrachloride-containing slurry enters a dry distillation kettle for distillation, obtaining a second recovery solvent at the top of the tower, and obtaining a distillation residue at the bottom of the tower; and performing solid-liquid separation treatment on at least one of the titanium tetrachloride-containing catalyst mother liquor, the titanium tetrachloride-containing slurry, and the distillation residue. The catalyst solvent recovery method of the present invention can prevent wastewater from being generated during the catalyst production process, and has obvious environmental protection and social benefits. However, this method uses a multi-tower distillation method to treat titanium tetrachloride mother liquor, and removes impurities by solid-liquid separation of the feed liquid. Not only is it difficult to remove soluble impurities such as titanate, but there are also problems such as difficulty in solid-liquid separation of titanium tetrachloride-rich feed liquid (prone to blockage, leakage, smoke, acid mist, etc.).

[0010] Chinese patent document CN113636593B discloses a method for recovering titanium-containing tower bottom liquid, comprising: 1) mixing the titanium-containing tower bottom liquid with an inert organic solvent to obtain a mixture of titanium-containing tower bottom liquid and an inert organic solvent; 2) allowing the obtained mixture to settle, and performing solid-liquid separation on the precipitate and supernatant liquid after settling; 3) distilling and separating the obtained supernatant liquid to obtain titanium tetrachloride and an organic solvent, wherein the titanium-containing tower bottom liquid is a tower bottom liquid obtained by distilling away all organic solvents and at least part of titanium tetrachloride from a titanium-based polyolefin catalyst mother liquid and / or a titanium treatment liquid. The method of the present invention significantly improves the utilization rate of raw materials, reduces the waste acid residue generated during the treatment process, and improves the recovery rate of titanium tetrachloride. However, the method uses a method of adding an inert solvent for precipitation to treat the titanium tetrachloride mother liquid, and then recovers the solvent and titanium tetrachloride respectively by distillation. The method requires the additional addition of a third component, which is easy to contaminate the recovered material, and at the same time, it is impossible to remove components such as soluble impurities such as titanates, and it is necessary to recover the inert organic components by distillation, resulting in high energy consumption.

[0011] Chinese patent document CN113636906A discloses a method for purifying a titanium-containing filtrate, which comprises: 1) evaporating the titanium-containing filtrate through a thin film evaporator to obtain a titanium-containing distillate; 2) mixing the titanium-containing distillate with an inert organic solvent to obtain a mixture; 3) allowing the mixture to settle, and performing solid-liquid separation on the settled precipitate and the supernatant; 4) performing distillation separation on the supernatant to obtain titanium tetrachloride and an organic solvent, wherein the titanium-containing filtrate is a mixture of one or more of a mother liquor produced in the preparation process of a propylene polymerization catalyst with a glycol ester compound as an electron donor and a titanium treatment liquid. The method of the present invention significantly improves the utilization rate of raw materials, reduces the waste acid residue produced during the treatment process, effectively removes non-metallic impurities in the filtrate, and improves the recovery rate of titanium tetrachloride. However, this method uses a thin film evaporation method to treat titanium tetrachloride mother liquor, and then recovers the solvent and titanium tetrachloride separately by distillation. This method requires the additional addition of a third component, which is easy to contaminate the recovered material. At the same time, soluble impurities such as titanate esters cannot be removed, and inert organic components need to be recovered by distillation, resulting in high energy consumption.

[0012] Chinese patent documents CN103420437B, CN103420413B, CN112707435A, etc. disclose adding white oil or other inert organic solvents to titanium-containing waste liquid to avoid scaling and blocking tendency in the distillation process and greatly improve the recovery rate of titanium tetrachloride. However, there is the problem of introducing a third component into the titanium-containing waste liquid, which not only makes it difficult to remove soluble impurities, but also has the risk of easily contaminating the catalyst. Summary of the invention

[0013] In view of this, the present invention provides a method for treating titanium-containing waste liquid, which utilizes high-boiling-point organic matter present in the catalyst preparation system as an inert solvent (such as decane, etc.), does not require the addition of a third component, and separates low-boiling-point fractions and target substances such as titanium tetrachloride in sequence through distillation. The distillation kettle liquid is washed with a washing liquid to thoroughly remove impurities such as solids and titanates, and the washed solvent is recovered or directly reused after dehydration treatment.

[0014] To achieve the above object, the present invention provides the following technical solutions:

[0015] A method for treating titanium-containing waste liquid, wherein the titanium-containing waste liquid is titanium-containing waste liquid containing an inert solvent generated during the preparation process of a Ziegler-Natta catalyst, comprising the following steps:

[0016] (1) distilling the titanium-containing waste liquid in a distillation tower, and controlling the low-boiling-point fraction with a normal-pressure boiling point of less than 135° C. to be discharged from the top of the tower;

[0017] (2) continuing to distill the material in the reactor of the distillation tower, separating the titanium tetrachloride material from the top of the tower, and separating the distillation residue containing a high boiling point solvent, a small amount of titanium tetrachloride and high boiling substances from the bottom of the tower;

[0018] (3) at a temperature lower than 60° C., the distillation residue is washed with a washing liquid and separated into phases to obtain an oil phase and a water phase; the oil phase is dehydrated and then partially or completely recycled to the distillation tower to be mixed with fresh titanium-containing waste liquid for further distillation;

[0019] The washing liquid is selected from water, the aqueous phase or an alkaline aqueous solution.

[0020] The distillation still residue contains a small amount of titanium tetrachloride, which reacts violently with water, usually with violent exothermic gas release. However, since the titanium-containing waste liquid generated during the preparation of the Ziegler-Natta catalyst contains some inert solvents (such as decane, etc.), the washing process of the washing liquid will be buffered. If there is no buffering of the inert solvent, side reactions, emulsification and other problems may occur during the washing of the washing liquid, and even toxicity may exist. Moreover, when washing the distillation residue with the washing liquid, the temperature should be controlled to be less than 60°C to avoid possible violent gas evolution and corrosion. According to the actual situation, washing can be carried out in batches and grades, or washing can be accompanied by temperature control measures such as jacket cooling.

[0021] Optionally, in the method for treating the titanium-containing waste liquid provided by the present invention, when the washing liquid is water, the water phase is directly recycled as the washing liquid after separation (such as by filtering to remove insoluble matter).

[0022] Optionally, in the method for treating the titanium-containing waste liquid provided by the present invention, when the washing liquid is an alkaline aqueous solution, the liquid obtained after solid-liquid separation of the aqueous phase is circulated as the washing liquid.

[0023] The titanium-containing waste liquid produced in the Ziegler-Natta catalyst preparation process includes components such as titanium tetrachloride, hydrocarbon solvents, electron donors, inert solvents (such as decane, hexane, etc.) and a small amount of alkoxy titanium. Since the alkoxy titanium contained in the rectification residue and the residual titanium tetrachloride will react when they meet water, generating acidic substances, therefore, the aqueous phase can be applied with acid water or after neutralization according to the situation, and certainly fresh washing liquid can be supplemented for washing treatment. When using alkaline aqueous solution as washing liquid, components such as titanium tetrachloride and alkoxy titanium will react violently with the washing liquid, generating salt and causing the alkali concentration of the alkaline washing liquid to reduce, and along with the growth of the number of times of application, the concentration of components such as titanium oxide and inorganic salt in the washing liquid will also increase and precipitate, and the washing liquid can be clarified by solid-liquid separation and then used (such as solid-liquid separation). According to actual conditions, the washing liquid can also be supplemented (such as adding the neutralized alkaline components) and adjusted to restore the washing liquid function.

[0024] Optionally, in the method for treating the titanium-containing waste liquid provided by the present invention, the mass ratio of the washing liquid to the distillation residue is 0.1 to 5.

[0025] Optionally, in the method for treating the titanium-containing waste liquid provided by the present invention, the mass ratio of the washing liquid to the distillation residue is 0.5 to 1.5.

[0026] Optionally, in the method for treating the titanium-containing waste liquid provided by the present invention, the oil phase is dehydrated in a manner selected from one or more of sedimentation, centrifugation, flash evaporation and adsorption.

[0027] Optionally, in the method for treating the titanium-containing waste liquid provided by the present invention, the distillation is selected from atmospheric distillation or vacuum distillation.

[0028] Optionally, in step (2) of the treatment method of the titanium-containing waste liquid provided by the present invention, during the distillation process, the liquid level in the distillation tower is controlled so that the heat exchange surface is always partially or fully submerged. The shell-and-tube type needs to be fully submerged, and the kettle jacket only needs to be partially submerged.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] The present invention uses the high-boiling-point organic component in the catalyst waste liquid system as an inert solvent, and does not need to add a third component, thereby effectively avoiding the pollution of the catalyst; after the titanium-containing waste liquid is distilled and separated into a low-boiling-point solvent and a part of titanium tetrachloride, the remaining distillation residue is washed and phase-separated with a water-containing washing liquid, and the obtained oil phase contains an inert solvent, which can be applied after removing water, thereby improving the recovery rate of the organic solvent and titanium tetrachloride in the titanium-containing waste liquid, and also effectively avoiding the coking, scaling and clogging problems in the distillation process of the existing method. Since the amount of titanium tetrachloride in the titanium-containing waste liquid cannot be accurately known, the present invention controls the residual amount of titanium tetrachloride in the distillation residue by controlling the kettle temperature, thereby realizing the evaluation of the recovery rate of titanium tetrachloride.

[0031] In addition, after distillation treatment, the components such as alkoxytitanium and titanium tetrachloride contained in the bottom residue can be completely decomposed and removed by water washing to avoid their accumulation in the inert solvent. The crude inert solvent after water washing can be dehydrated and refined to obtain an inert solvent finished product that meets the reuse requirements. The water washing liquid can be recycled, and the precipitated titanium oxide and inorganic salt can be recovered by solid-liquid separation. The HCl gas produced in the hydrolysis reaction can be collected separately, or the HCl gas or hydrochloric acid solution can be obtained by evaporating the washing liquid. The precipitate in the water washing liquid can be made into titanium dioxide after solid-liquid separation and can be recycled. When an alkaline solution is used as the water washing liquid, inorganic salt crystals can be obtained after evaporation and crystallization of the water washing liquid. The treatment method provided by the present invention has the characteristics of strong industrial application feasibility, low treatment cost, high degree of resource utilization, etc., and is a method that can achieve green treatment of titanium-containing waste liquid. DETAILED DESCRIPTION

[0032] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0033] Example 1

[0034] 150g of titanium-containing waste liquid produced by Ziegler-Natta catalyst (containing 30g of decane) is added to a 500ml three-necked flask and mixed evenly, and atmospheric distillation is performed at a tower bottom temperature of 90-165°C. First, the hexane fraction (light component) is separated from the top of the distillation tower, and then atmospheric distillation is continued under the condition that the kettle temperature is 165-180°C, the tower bottom temperature, titanium tetrachloride material is separated from the top of the distillation tower, and the distillation residue is discharged from the bottom of the distillation tower. The distillation residue is slowly added dropwise to 120g of tap water for sufficient water washing (the mass ratio of tap water to the tower bottom residue is controlled to be 2.0), the temperature of the water washing system is controlled below 35°C, and then the phases are allowed to stand for phase separation to obtain an oil phase and an aqueous phase. The oil phase is flashed and dehydrated and then recycled to the distillation tower for reuse; the aqueous phase is filtered and then recycled as a washing liquid.

[0035] Example 2

[0036] 187g of titanium-containing waste liquid (containing 37g of decane) produced by Ziegler-Natta catalyst was added to a 500ml three-necked flask and mixed evenly, and normal pressure distillation was performed at a tower bottom temperature of 90-165°C, and the hexane fraction was separated from the top of the distillation tower. After the hexane was distilled out, 9g of recovered decane was added to the distillation tower kettle and mixed evenly, and vacuum distillation was performed under the conditions of a tower kettle temperature of 100-140°C and a vacuum degree of -0.099-0.085Mpa, and titanium tetrachloride material was separated from the top of the distillation tower. After the distillation is completed, the residual liquid in the tower bottom is transferred and slowly dripped into 100g of NaOH solution with a mass concentration of 15% for thorough water washing (the mass ratio of sodium hydroxide solution to the residual liquid in the tower bottom is controlled to be 4), the temperature of the water washing system is controlled below 40°C, and the oil phase is allowed to stand for separation. After the oil phase is washed with water, it is subjected to adsorption dehydration (the dehydrating agent used for adsorption is molecular sieve) treatment to achieve recycling; the water phase is filtered and the water phase after solid-liquid separation can be recycled.

[0037] Example 3

[0038] 200g of titanium-containing waste liquid (containing 50g of decane) produced by Ziegler-Natta catalyst was added to a 500ml three-necked flask and mixed evenly, and normal pressure distillation was performed at a tower bottom temperature of 90-165°C, and the hexane fraction was separated from the top of the distillation tower. After the hexane was distilled out, 45g of recovered decane was added to the distillation tower kettle and mixed evenly, and vacuum distillation was performed under the conditions of a tower bottom temperature of 100-140°C and a vacuum degree of -0.099-0.085Mpa, and titanium tetrachloride material was separated from the top of the distillation tower. After the distillation is completed, the residual liquid in the tower bottom is transferred and slowly added dropwise to 100g of the washing liquid recovered in Example 1 for sufficient water washing (the mass ratio of the washing liquid to the residual liquid in the tower bottom is controlled to be 0.3), the temperature of the water washing system is controlled below 35°C, and the oil phase is allowed to stand for separation. After water washing, the oil phase is flashed and adsorbed (the dehydrating agent used for adsorption is calcium chloride) for recycling; the aqueous phase is filtered and the aqueous phase after solid-liquid separation can be recycled.

[0039] Of course, the present invention may have many other embodiments and variations thereof. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and variations based on the present invention, but these corresponding changes and variations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for treating titanium-containing waste liquid, wherein the titanium-containing waste liquid is titanium-containing waste liquid containing an inert solvent generated during the preparation of a Ziegler-Natta catalyst, characterized in that: The steps include: (1) distilling the titanium-containing waste liquid in a distillation tower, and controlling the low-boiling-point fraction with a normal-pressure boiling point of less than 135° C. to be discharged from the top of the tower; (2) continuing to distill the material in the reactor of the distillation tower, separating the titanium tetrachloride material from the top of the tower, and separating the distillation residue from the bottom of the tower; (3) at a temperature lower than 60° C., the distillation residue is washed with a washing liquid and separated into phases to obtain an oil phase and a water phase; the oil phase is dehydrated and then partially or completely recycled to the distillation tower to be mixed with fresh titanium-containing waste liquid for further distillation; The washing liquid is selected from water, the aqueous phase or an alkaline aqueous solution.

2. The method for treating titanium-containing waste liquid according to claim 1, characterized in that: When the washing liquid is water, the aqueous phase is separated and then recycled as the washing liquid.

3. The method for treating titanium-containing waste liquid according to claim 1, characterized in that: When the washing liquid is an alkaline aqueous solution, the liquid obtained after solid-liquid separation of the aqueous phase is circulated as the washing liquid.

4. The method for treating titanium-containing waste liquid according to claim 2, characterized in that: The mass ratio of the washing liquid to the distillation residue is 0.1-5.

5. The method for treating titanium-containing waste liquid according to claim 2, characterized in that: The mass ratio of the washing liquid to the distillation residue is 0.5 to 1.

5.

6. The method for treating titanium-containing waste liquid according to claim 1, characterized in that: The oil phase is dehydrated in one or more ways selected from sedimentation, centrifugation, flash evaporation and adsorption.

7. The method for treating titanium-containing waste liquid according to claim 1, characterized in that: In step (2) and step (3), the distillation is selected from atmospheric distillation or vacuum distillation.

8. The method for treating titanium-containing waste liquid according to claim 1, characterized in that: In step (2), during the distillation process, the liquid level in the distillation tower is controlled so that the heat exchange surface is always partially or fully submerged.