Process for recycling all components of printing and dyeing white mud

Abstract

The application discloses a kind of printing and dyeing white mud full-component resource recycling processes, comprising: white mud is added after dehydration and drying solvent, is dissolved by heating and filters while hot, obtain filter cake one and filtrate one;Filtrate one is added by crystallization, filtration and obtains filter cake two and filtrate two, filter cake two is dried after recovering solvent and obtains high-purity PTA, filtrate two is used with condensed solvent for the next batch white mud dissolution;Filtrate two is used for multiple times after adding water, and the remaining PTA is recovered by solvating crystallization, obtains filter cake three and filtrate three;Filtrate three is separated by rectification and obtains water, high-purity solvent and pitch, water is used for solvating crystallization, solvent is used for dissolution, pitch is mixed with filter cake one and is obtained by segmented high-temperature cracking and is cracked gas, cracking oil and carbon, and combustion heat is used for energy-consuming section.The beneficial effects of the present application are that by the technical combination of addition crystallization, solvent reuse, rectification and segmented high-temperature cracking, the efficient recovery of PTA and solvent and the heat energy utilization of impurities are realized, which significantly improves the resource utilization level of white mud in printing and dyeing industry.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, and in particular relates to a process for the resource recovery of all components of dyeing and printing white mud. Background Technology

[0002] Textile dyeing sludge is a type of solid waste generated during the treatment of dye wastewater in the textile dyeing industry. This solid waste contains a large amount of terephthalic acid (PTA) and small amounts of other organic components. Due to the large production volume and high difficulty in disposal, improper treatment of textile dyeing sludge can easily cause environmental pollution. Therefore, the harmless treatment and resource utilization of textile dyeing sludge is a technical problem that the dyeing industry needs to solve. To address this issue, some patents have proposed methods for the resource utilization of textile dyeing sludge. Chinese patent (CN105646198A) extracts pure PTA from dyeing and printing sludge by combining addition crystallization with mechanical crushing; Chinese patent (CN106588638B) obtains PTA by mixing dyeing and printing sludge with water, high-temperature activated carbon, descaling agent and composite finishing agent into a high-temperature slurry, and then filtering it under high temperature and high pressure, depressurizing crystallization, cooling and dehydration; Chinese patent (CN108101774A) obtains high-purity PTA by distillation, cooling crystallization and multiple solid-liquid separations.

[0003] However, the aforementioned existing technologies generally only focus on extracting PTA from white mud, while other components such as solvents and organic residues are mostly discharged as by-product waste liquids or solid wastes, which not only wastes resources but also creates a burden for subsequent treatment. Summary of the Invention

[0004] To address the aforementioned technical problems in existing technologies, this application aims to provide a process for the resource-based recovery of all components of dyeing and printing white mud. The process proposed in this invention not only efficiently recovers high-purity PTA but also enables the resource-based utilization of all components, including solvents, water, and asphalt. Particularly concerning are the organic residues that cannot be properly disposed of using existing technologies. This invention innovatively introduces segmented high-temperature pyrolysis technology, first recovering residual solvents and then converting impurities such as asphalt into clean secondary energy products such as pyrolysis gas, pyrolysis oil, and char. This completely avoids the equipment blockage and coking problems caused by the direct combustion of high-viscosity asphalt in the tower bottom, achieving deep conversion and clean utilization of non-reusable components. Simultaneously, the heat generated from the combustion of pyrolysis products is recycled to energy-consuming sections, achieving full-process thermal energy self-balance. The entire process generates virtually no wastewater or solid waste requiring external discharge, thus achieving near-zero emission resource recovery of all components of dyeing and printing white mud.

[0005] The technical solution adopted in this invention is as follows: A process for the complete resource recovery of dyeing and printing white mud includes the following steps: S1: Dry and dehydrate the white mud after it has been washed and deacidified by water; S2: The dried white mud is added to a solvent, heated to dissolve, and then filtered while hot to obtain filter cake 1 and filtrate 1; S3: Filtrate 1 is subjected to addition crystallization and filtration separation to obtain filter cake 2 and filtrate 2. After drying and solvent recovery of filter cake 2, high-purity PTA product is obtained. The dried and recovered solvent and filtrate 2 are reused in step S2. S4: After the second filtrate described in step S3 has been used 3-8 times, water is added to allow the remaining PTA in the second filtrate to precipitate out quickly through dissolution and crystallization. Solid-liquid separation is then performed to obtain filter cake three and filtrate three. Filter cake three is directly recycled to the dissolution section of step S2. S5: The filtrate is separated into water, high-purity solvent and asphalt by distillation. The high-purity solvent has a purity of over 99.5% and is recycled for step S2. The asphalt is mixed with filter cake and then subjected to staged pyrolysis to obtain high-calorific-value cracked gas, cracked oil and char.

[0006] Furthermore, in step S1, the moisture content of the dried white mud is controlled to be below 3%.

[0007] Further, in step S2, the solvent is N,N-dimethylformamide or N,N-dimethylacetamide, which can form adduct crystals with PTA terephthalic acid; in step S2, the mass of the solvent is 8-10 times the dry weight of the white mud, and the dissolution temperature is 80-100℃.

[0008] Furthermore, in step S3, the addition crystallization process involves cooling the filtrate to room temperature for at least 1 hour, during which the PTA in the filtrate combines with the solvent to form addition crystals.

[0009] Furthermore, in step S4, the mass of water used during dissolution and crystallization is 15-20% of the total mass of the filtrate.

[0010] Furthermore, in step S5, the distillation recovery rate of the high-purity solvent is controlled at 80-90% during the distillation operation, and the remaining solvent remains in the asphalt to improve the fluidity of the asphalt.

[0011] Furthermore, the segmented pyrolysis treatment includes the following steps: under nitrogen protection, the temperature is first raised from room temperature to 200-250℃, and then kept constant until the residual solvent in the asphalt is basically recovered; then the temperature is raised to the pyrolysis temperature and kept constant until pyrolysis gas and pyrolysis oil are no longer produced, and the gaseous and liquid products after condensation at each stage and the final residual carbon are collected; the pyrolysis temperature is 500-600℃.

[0012] Furthermore, it also includes the following process: the cracked oil, cracked gas and carbon obtained from the segmented pyrolysis treatment are fed into a low-pressure steam boiler for combustion, and the heat generated by combustion is used to heat water to prepare low-pressure saturated steam, which serves as the heat source for the drying section in step S1, the dissolution section in step S2 and the distillation section in step S5.

[0013] Furthermore, in step S4, when the filtrate is reused 3-8 times, water is added for dissolution and crystallization.

[0014] Furthermore, based on the total mass fraction of the components other than water in the dyeing and printing white mud being 100%, the mass fraction of PTA is 65-80%, the mass fraction of oligomer impurities is 19-34%, and the remainder is insoluble impurities.

[0015] This invention abandons the traditional approach of only recovering PTA and constructs a process flow of "addition crystallization - filtrate circulation - distillation - segmented high-temperature pyrolysis" to realize the resource utilization of all components such as PTA, solvent, water and asphalt in dyeing and printing white mud.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The process of this invention achieves a total PTA recovery rate of ≥99% through the synergistic effect of addition crystallization and dissolution crystallization, which significantly improves the resource utilization rate of PTA in dyeing and printing white mud.

[0017] 2. The process of this invention achieves a total solvent recovery rate of ≥99% and a solvent purity of ≥99.5% after recovery by coupling distillation separation and segmented high-temperature pyrolysis. At the same time, the solvent can be reused multiple times, which greatly reduces solvent consumption and waste liquid discharge.

[0018] 3. This invention converts organic impurities other than PTA into byproducts such as cracked gas, cracked oil and carbon through segmented high-temperature pyrolysis, and produces low-pressure saturated steam by burning the pyrolysis products to provide heat for each energy-consuming section, which significantly reduces the energy consumption and cost of the process operation, and at the same time truly realizes the resource recovery of all components in the dyeing and printing white mud. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0021] Example: Comparison Figure 1The present invention discloses a process for the resource recovery of all components of dyeing and printing white mud, the main steps of which include: firstly, drying and dehydrating the white mud obtained from the dyeing and printing enterprise, controlling the water content of the dried white mud to be less than 3%, then dissolving the dried white mud by stirring with N,N-dimethylformamide or N,N-dimethylacetamide at 80-100 ℃, and then filtering or centrifuging under heat preservation conditions to obtain filter cake one and filtrate one. Filter cake one is an insoluble impurity, and filtrate one enters the addition crystallization section.

[0022] The specific operation of the addition crystallization section is as follows: filtrate one is introduced into a crystallization tank, and the solution inside the crystallization tank is continuously stirred while being slowly cooled to room temperature, allowing the PTA terephthalic acid in the solution to combine with the solvent to form addition crystals. A cooling jacket is installed on the outside of the crystallization tank, and cooling water is circulated into the cooling jacket. By controlling the flow rate of the cooling water, the crystallization temperature is cooled at a relatively uniform rate, and the cooling time to room temperature is controlled to be no less than 1 hour. The liquid-solid mixture after addition crystallization is filtered or centrifuged to obtain filter cake two and filtrate two. Filter cake two is the addition crystal. The obtained addition crystals can be dried directly or collected in multiple batches and dried centrally.

[0023] Solvent is also recovered during the drying process of the addition crystals. The method of solvent recovery is a conventional existing technology, namely, setting up a cold trap to condense and collect the solvent that evaporates during drying, thus obtaining condensed solvent. The operating conditions for drying the addition crystals are: drying temperature 130-160 ℃, drying pressure 0.5-2 kPa, and time 2-3 hours. The high-purity solid PTA obtained after drying is bagged and stored. The filtrate and the condensed solvent can be reused in the dissolution section for dissolving white mud.

[0024] Furthermore, after the second filtrate is reused 3-8 times, water is added to allow PTA to precipitate completely through dissolution and crystallization. The water mass is 15-20% of the total mass of the second filtrate. After solid-liquid separation, filter cake three and filtrate three are obtained. Filter cake three is mixed with the raw material white mud and reused, that is, returned to the dissolution section for dissolving white mud. Filtrate three is then distilled to separate water, high-purity solvent, and asphalt. The water is reused in the dissolution and crystallization section for the precipitation of PTA, and the high-purity solvent is reused in the dissolution section for dissolving white mud.

[0025] Furthermore, in the distillation operation of filtrate three, the distillation recovery rate of high-purity solvent is controlled at 80-90%, and the remaining solvent remains in the asphalt to improve the fluidity of the asphalt.

[0026] After mixing asphalt and filter cake, a staged pyrolysis process is carried out, including the following steps: under nitrogen protection, the temperature is first raised from room temperature to 200-250℃, and then kept constant for 10-40 minutes until the residual solvent in the asphalt is basically recovered; then the temperature is raised to the pyrolysis temperature and kept constant for 30-60 minutes until pyrolysis gas and pyrolysis oil are no longer produced, and the gaseous and liquid products after condensation at each stage and the final residual carbon are collected; the pyrolysis temperature is 500-600℃.

[0027] The white mud obtained from dyeing and printing enterprises in this invention, after being washed and deacidified, has the following composition (excluding water): 75% PTA by mass, 24% oligomer impurities by mass, and 1% insoluble impurities. The white mud has a water content of 50% and a pH of 6-7.

[0028] Example 1: Using as follows Figure 1 The process shown recovers PTA from white mud, including the following steps: S1: The white mud, after being washed and deacidified by water, is dried until the moisture content of the white mud is less than 3%; S2: Take 10 g of dried white mud and 90 g of N,N-dimethylacetamide, stir at 85℃ until the white PTA solid is completely dissolved, keep warm and filter while hot to obtain filter cake one and filtrate one; S3: Filtrate 1 is introduced into a crystallization tank. The solution in the crystallization tank undergoes addition crystallization at a stirring speed of 100 rpm, while the solution is simultaneously cooled slowly and uniformly to room temperature over a period of 1 hour. This allows the PTA terephthalic acid in the solution to combine with the solvent to form addition crystals. After the solution cools to room temperature, it is filtered to separate the addition crystals into filter cake 2 and filtrate 2. Filter cake 2 is collected for later use.

[0029] The filtrate is then replenished with fresh N,N-dimethylacetamide until the total mass of the solution reaches 90 g, forming a 90 g reuse solution. This solution is then reused in the dissolution stage of step S2, where 10 g of dried white mud is added to the 90 g reuse solution, and the solution is heated, dissolved, and kept warm before being filtered and separated.

[0030] S4: After using the second filtrate from step S3 four times, a total of five batches of addition crystal filter cake 2 (91 g) and the second filtrate from the final solid-liquid separation (88 g) were obtained. The five batches of addition crystal filter cake 2 (91 g) were dried at 2 kPa and 140 ℃ for 3 h to obtain 37.1 g of PTA product with a purity of 98.2%. During the drying process, the solvent that evaporated during drying was condensed and collected using a cold trap to obtain the condensed solvent.

[0031] S5: Add 17.6 g of deionized water to 88 g of the filtrate obtained from the last solid-liquid separation for dissolution and crystallization. After stirring for 1 minute, separate the solid and liquid phases and dry the solid to obtain 0.8 g of PTA solid with a purity of 91.1%. The total mass of PTA obtained in the above steps is 37.1 g × 0.982 + 0.8 g × 0.911 = 37.16 g, and the total PTA recovery rate is 99.09%.

[0032] Example 2: Using as follows Figure 1 The process shown recovers the solvent used in the purification process and performs staged high-temperature cracking of the pitch in the distillation bottoms: Step 1: Distillation to recover the solvent In Example 1, 88 g of filtrate two obtained from the final solid-liquid separation was mixed with 17.6 g of deionized water for dissolution and crystallization. After stirring for 1 minute, solid-liquid separation was performed to obtain filtrate three, which underwent two-stage distillation. First, under absolute pressure of 20 kPa, filtrate three was introduced into the first plate distillation column, and dehydrated to a water content of less than 500 ppm at a controlled top temperature of 55-65 ℃. Then, under absolute pressure of 20 kPa, the dehydrated filtrate three was introduced into the bottom of the second plate distillation column, and N,N-dimethylacetamide solvent was distilled off from the top at a controlled top temperature of 110-120 ℃. The purity of the obtained N,N-dimethylacetamide solvent was greater than 99.5%. The distillation recovery rate of N,N-dimethylacetamide solvent in the dehydrated filtrate three was controlled at about 90%, with about 10% of the solvent remaining in the asphalt to ensure that the asphalt in the bottom of the column has a certain fluidity so that the subsequent staged high-temperature pyrolysis can proceed normally. In addition, by collecting the solvent condensed during the drying of the addition crystals in Example 1, and combining it with the solvent recovered during the subsequent high-temperature pyrolysis of the pitch segment in the bottom of the tower, it can be ensured that there is almost no solvent loss in the entire process, and the total solvent recovery rate is greater than 99%.

[0033] Step 2: High-temperature segmented pyrolysis 300 g of silicon carbide particles are filled into a quartz glass reactor to form a silicon carbide bed. The surface of the silicon carbide bed is a circular plane with a diameter of 120 mm.

[0034] 26 g of the distillation residue obtained in Example 2 was mixed with 0.4 g of filter cake obtained in step S2 of Example 1. The mixture was spread onto a 300 g silicon carbide bed with a diameter of 120 mm using a liquid addition funnel. A quartz glass reactor containing the asphalt and the silicon carbide bed was placed in a microwave high-temperature pyrolysis apparatus. Nitrogen gas was introduced to maintain a positive pressure of 5 kPa. The microwave power was set to 1500 W, and heating was initiated. During this process, the gas exiting the quartz glass reactor was condensed and collected. The temperature was raised to 200 °C in 3 minutes and then stabilized for 20 minutes. 13.63 g of N,N-dimethylacetamide, a liquid solvent, was collected by condensation. The temperature was further increased to 550 °C in 6 minutes and then stabilized for 40 minutes. 9.64 g of pyrolysis oil and 2.09 g of non-condensable pyrolysis gas were collected by condensation. Heating was then stopped, and after cooling, 1.04 g of solid carbon was obtained from the silicon carbide bed. The pyrolyzed silicon carbide bed was loose and showed no coking or wall adhesion.

[0035] Comparative Example 1: The experimental steps of Comparative Example 1 were repeated in Example 2, except that "in the operation of distillation to recover the solvent in step 1, during the second-stage distillation, the temperature of the pot of the second plate distillation column was increased and the distillation time was extended so that the N,N-dimethylacetamide solvent was almost completely distilled off during the distillation stage (the N,N-dimethylacetamide solvent content in the asphalt was less than 1%)".

[0036] The experimental results of Comparative Example 1 show that during the second-stage distillation process, as the solvent is completely removed, the residual asphalt in the bottom of the second plate distillation column gradually solidifies into a gel with extremely high viscosity, which cannot be dripped onto the silicon carbide bed through the addition funnel.

[0037] In Comparative Example 1, 15 g of the aforementioned gelled asphalt was poured onto a 300 g silicon carbide bed with a diameter of 120 mm. The asphalt was piled up in large lumps in a localized area of ​​the bed and agglomerated with some silicon carbide particles. A quartz glass reactor containing the gelled asphalt and the silicon carbide bed was placed in a microwave high-temperature pyrolysis device. Nitrogen gas was introduced to maintain a positive pressure of 5 kPa. The microwave power was set to 1500 W, and heating was started. During this period, the gas at the outlet of the quartz glass reactor was condensed and collected. After heating to 550 °C for 10 minutes, the temperature was kept constant for 40 minutes. 4.23 g of pyrolysis oil and 0.89 g of non-condensable pyrolysis gas were collected. After heating was turned off and cooling was performed, it was found that the carbonaceous products contained a large amount of incompletely pyrolyzed asphalt residue, and the solid carbon was tightly bonded to the silicon carbide particles to form hard coke lumps. The solid carbon could not be effectively separated and recovered from the silicon carbide bed, resulting in the waste of the silicon carbide bed.

[0038] The comparative experiments in Example 2 and Comparative Example 1 show that if the solvent is completely evaporated in the distillation stage, the bottom asphalt will lose its fluidity and solidify. Solidified asphalt cannot be heated evenly during high-temperature pyrolysis, easily causing coking and blockage in the equipment, and significantly reducing the yield of pyrolysis products. This invention, by controlling the solvent recovery rate at approximately 90% during the distillation stage, preserves the fluidity of the asphalt, allowing it to spread evenly on the surface of the silicon carbide bed, thereby ensuring the smooth progress of staged high-temperature pyrolysis and the effective recovery of high-value products.

[0039] Example 3: Using as follows Figure 1 The process shown utilizes the heat generated by the combustion of high-temperature pyrolysis products to achieve a closed-loop thermal energy recovery of dyeing and printing white mud (with 5 cycles constituting one cycle): Take 5 kg of dried dyeing and printing mud and divide it into 5 batches (1 kg per batch). Following the method in Example 1, dissolve the first batch of mud in 9 kg of N,N-dimethylacetamide (DMAC) and purify it according to steps S2-S3 of Example 1. The resulting filtrate is then replenished with fresh DMAC and used directly for dissolving the second batch of mud. This process is repeated until filtrate is reused for dissolving the fifth batch of mud, resulting in a total of five batches of addition crystal filter cakes and a final solid-liquid separation filtrate enriched with impurities.

[0040] Five batches of adduct crystal filter cake, totaling 9.11 kg, were dried at 2 kPa and 140 °C for 3 h, resulting in a total of approximately 5.45 kg of evaporated DMAC.

[0041] The second filtrate, enriched with impurities from the final solid-liquid separation, was subjected to two-stage distillation according to step 1 of Example 2. The first stage of distillation dehydrated the solution to a water content below 500 ppm. The second stage of distillation recovered the solvent under the following operating conditions: absolute pressure of 20 kPa and a reflux ratio controlled at 2. During the second stage of distillation, a total of 8.9 kg of DMAC solvent was collected from the top of the column, and approximately 2.57 kg of asphalt containing impurities was collected from the bottom of the column.

[0042] The aforementioned asphalt containing impurities was subjected to staged high-temperature pyrolysis according to step 2 of Example 2. In the first stage, 1.32 kg of liquid solvent N,N-dimethylacetamide was collected by condensation. In the second stage, approximately 0.98 kg of pyrolysis oil, approximately 0.18 kg of pyrolysis gas, and approximately 0.09 kg of solid carbon residue were collected. The collected pyrolysis oil, pyrolysis gas, and solid carbon were fed into a low-pressure steam boiler for complete combustion. The heat generated from the combustion heated water to prepare low-pressure saturated steam with an absolute pressure of 0.3 MPa, which served as the sole heat source for the entire purification process.

[0043] The heat consumption and generation of the system in the above-mentioned purification process of dyeing and printing white mud are analyzed as follows: Furthermore, the mass fraction of DMAC in the adduct crystal is approximately 60%. The energy consumption and generation throughout the entire process are as follows: First, in the process of resource recovery of all components of dyeing and printing white mud according to the present invention, the main energy-consuming sections are raw material dissolution, product drying, and solvent recovery by filtrate distillation, as calculated below: ① Five batches of white clay were heated and dissolved, using a total of 5 kg of white clay and 45 kg of DMAC. Each batch was stirred at 85℃ until the white PTA solid was completely dissolved. The heating and dissolution process involved raising the temperature from room temperature to 85℃, with a temperature rise of approximately 60℃.

[0044] Given that the specific heat capacity of PTA is 1.2 kJ / (kg·℃) and the specific heat capacity of DMAC is 2.0 kJ / (kg·℃), and since the composition of white mud is relatively complex and the main component is PTA, the specific heat capacity of white mud and its impurities is approximated to the specific heat capacity of PTA (i.e., 1.2 kJ / (kg·℃)).

[0045] Therefore, the sensible heat of dissolution of the 5 batches of white clay is 5 × 1.2 × 60 kJ + 45 × 2.0 × 60 kJ = 5760 kJ.

[0046] ② Five batches of addition crystal filter cake were dried and the solvent was evaporated, with a total of approximately 5.45 kg of DMAC evaporated. The latent heat of vaporization of DMAC is 500 kJ / kg.

[0047] Therefore, the latent heat of vaporization of the solvent evaporated during the drying of the five batches of additive crystal filter cake is 5.45 × 500 kJ / kg = 2725 kJ.

[0048] ③ The filtrate enriched with impurities from the final solid-liquid separation, and the latent heat of the reboiler in the second plate distillation column for solvent recovery via distillation. Because the reflux ratio R is 2, a total of 8.9 kg of DMAC solvent is collected from the top of the column during the second-stage distillation process (i.e., the amount of DMAC collected from the top of the column is D = 8.9 kg). Therefore, the amount of rising vapor in the second-stage distillation column is V = D × (1 + R) = 26.7 kg, and the latent heat of the reboiler is 26.7 kg × 500 kJ / kg = 13360 kJ.

[0049] In summary, the total energy consumption of the three main processes—raw material dissolution, product drying, and solvent recovery by filtrate distillation—is 5760kJ + 2725kJ + 13360kJ = 21845 kJ.

[0050] Second, the total combustion heat of the high-calorific-value pyrolysis gas, pyrolysis oil, and char obtained from the staged pyrolysis process is calculated. The higher heating values ​​of the cracked oil, cracked gas, and char are 28,000 kJ / kg, 7,500 kJ / kg, and 30,000 kJ / kg, respectively.

[0051] The calorific value of the cracked oil is 0.98 kg × 28000 kJ / kg = 27440 kJ, the calorific value of the cracked gas is 0.18 kg × 7500 kJ / kg = 1350 kJ, and the calorific value of the char is 0.09 kg × 30000 kJ / kg = 2700 kJ.

[0052] In summary, the total combustion heat of the high-calorific-value pyrolysis gas, pyrolysis oil, and char obtained by the complete resource recovery of the dyeing and printing white mud in the process of this invention is 27440kJ + 1350kJ + 2700kJ = 31490 kJ.

[0053] It can be seen that when the process described in this patent is used to recycle all components of dyeing and printing white mud in a cycle of 5 cycles, a closed-loop heat system with zero external energy input can be achieved.

[0054] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A process for the complete resource recovery of dyeing and printing white mud, characterized in that, Includes the following steps: S1: Dry and dehydrate the white mud after it has been washed and deacidified by water; S2: The dried white mud is added to a solvent, heated to dissolve, and then filtered while hot to obtain filter cake 1 and filtrate 1; S3: Filtrate 1 is subjected to addition crystallization and filtration separation to obtain filter cake 2 and filtrate 2. After drying and recovering the solvent from filter cake 2, terephthalic acid PTA product is obtained. The dried and recovered solvent and filtrate 2 are reused in step S2. S4: After the second filtrate described in step S3 is used several times, water is added to allow the remaining terephthalic acid PTA in the second filtrate to precipitate rapidly through dissolution and crystallization. Solid-liquid separation is then performed to obtain filter cake three and filtrate three. Filter cake three is directly recycled to the dissolution section of step S2. S5: The filtrate is separated into water, high-purity solvent and asphalt by distillation. The high-purity solvent has a purity of over 99.5% and is recycled for step S2. The asphalt is mixed with filter cake and then subjected to staged pyrolysis to obtain cracked gas, cracked oil and char.

2. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, In step S1, the moisture content of the dried white mud is controlled to be below 3%.

3. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, In step S2, the solvent is N,N-dimethylformamide or N,N-dimethylacetamide, which can form adduct crystals with PTA terephthalic acid; in step S2, the mass of the solvent is 8-10 times the dry weight of the white mud, and the dissolution temperature is 80-100 ℃.

4. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, In step S3, the addition crystallization process involves cooling the filtrate to room temperature for at least 1 hour. During the cooling process, the terephthalic acid (PTA) in the filtrate combines with the solvent to form addition crystals.

5. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, In step S4, the mass of water used during dissolution and crystallization is 15-20% of the total mass of the filtrate.

6. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, In step S5, the high-purity solvent recovery rate is controlled at 80-90% during the distillation operation, and the remaining solvent remains in the asphalt to improve the fluidity of the asphalt.

7. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, The segmented pyrolysis process includes the following steps: under nitrogen protection, the temperature is first raised from room temperature to 200-250℃, and then kept constant until the residual solvent in the asphalt is completely recovered; then the temperature is raised to the pyrolysis temperature and kept constant until pyrolysis gas and pyrolysis oil are no longer produced, and the gaseous and liquid products after condensation at each stage and the final residual carbon are collected; the pyrolysis temperature is 500-600℃.

8. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, It also includes the following process: the cracked oil, cracked gas and carbon obtained from the segmented pyrolysis treatment are fed into a steam boiler for combustion, and the heat generated by combustion is used to heat water to prepare saturated steam, which serves as the heat source for the drying section in step S1, the dissolving section in step S2 and the distillation section in step S5.

9. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, In step S4, when the filtrate has been reused 3-8 times, water is added for dissolution and crystallization.

10. The process for the complete resource recovery of dyeing and printing white mud as described in claim 1, characterized in that, Based on the total mass fraction of the components of the dyeing and printing white mud excluding water being 100%, the mass fraction of terephthalic acid (PTA) is 65-80%, the mass fraction of oligomer impurities is 19-34%, and the remainder is insoluble impurities.

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