Heating-based purification method of high-yield electronic-grade hydrochloric acid

Abstract

The invention provides a method for purifying high-yield electronic grade hydrochloric acid based on heating. The method comprises five subsystems, namely a hydrochloric acid purification and absorption system, a dilute sulfuric acid concentration and regeneration system, a 18 megohm ultrapure water system, a protective gas system and a cooling water system. According to the hydrochloric acid purification and absorption system, hydrogen chloride gas is purified through a 98wt% concentrated sulfuric acid washing tower, and moisture and metal ions are removed; the purified hydrogen chloride gas is sequentially introduced into a four-stage quartz glass falling film absorption tower to be in countercurrent contact with ultrapure water for deep absorption, different liquid-gas ratios and temperatures are controlled, and finally the electronic-grade hydrochloric acid with the concentration of 36.5-37.0% is obtained. The dilute sulfuric acid concentration regeneration system performs preheating, vacuum evaporation and crystallization treatment on dilute sulfuric acid generated in the purification process, and regenerated concentrated sulfuric acid with the concentration larger than or equal to 98% is obtained through recovery. According to the method, through multi-stage absorption and strict process parameter control, high-yield purification of the electronic-grade hydrochloric acid is achieved, the product purity is high, and the total amount of metal impurities is lower than 500 ppb.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of hydrochloric acid purification, and particularly relates to a high-yield electronic-grade hydrochloric acid purification method based on heating. BACKGROUND

[0002] Hydrochloric acid is an indispensable basic chemical in the high-tech industries such as semiconductors, electronics and optoelectronics, and the purity of the hydrochloric acid directly affects the performance and yield of electronic devices. With the continuous reduction of the process node of integrated circuits, the purity requirement of electronic-grade hydrochloric acid is also getting higher and higher, especially the control of metal ions, particulate matter and oxidizing impurities is more stringent.

[0003] However, there are still some problems in the purification process of electronic-grade hydrochloric acid in the prior art: first, the traditional electronic-grade hydrochloric acid purification process usually needs complex equipment and multiple processes, resulting in high production cost; second, the removal rate of metal impurities in the prior art is insufficient, which is difficult to meet the requirements of advanced electronic industry for ultra-pure hydrochloric acid; third, the value utilization rate of chlorine resources is low, and the by-product recovery and utilization is insufficient; finally, the preparation of electronic-grade chemicals has the characteristics of harsh production conditions and high technical threshold, and the stability and controllability of the existing process still need to be improved. Especially in the preparation process of high-concentration hydrochloric acid, how to effectively control the temperature and efficiency of the absorption process, and how to realize the efficient regeneration and utilization of concentrated sulfuric acid, are the technical problems to be solved at present. SUMMARY

[0004] The technical problem to be solved by the application is that the traditional electronic-grade hydrochloric acid purification process has the defects of high production cost, insufficient removal rate of metal impurities, low value utilization rate of chlorine resources and harsh production conditions and high technical threshold of electronic-grade chemical preparation, and a high-yield electronic-grade hydrochloric acid purification method based on heating is provided.

[0005] The technical solution adopted by the application to solve the technical problem is to provide a high-yield electronic-grade hydrochloric acid purification method based on heating, which comprises five subsystems: a hydrochloric acid purification and absorption system, a dilute sulfuric acid concentration and regeneration system, an 18 mega-ohm ultra-pure water system, a protective gas system and a cooling water system. The hydrochloric acid purification and absorption system comprises two steps of hydrogen chloride gas concentration and multi-stage ultra-pure water absorption.

[0006] Preferably, in the hydrogen chloride gas purification step with concentrated sulfuric acid, hydrogen chloride gas, a byproduct of the caustic soda unit, with a purity of 90-96% and a temperature ≤40℃, is used. This gas is passed through a scrubbing tower filled with 98wt% concentrated sulfuric acid, with a gas velocity controlled at 0.3-0.5 m / s. This removes moisture and some metal ions from the gas. The sulfuric acid temperature is maintained at 40±2℃, and the sulfuric acid is temperature-controlled via a cooling water system with a residence time ≥15 seconds. This removes impurities such as Fe, Cl2, and organic matter, resulting in purified hydrogen chloride gas with a total metal impurity content <500 ppb.

[0007] Furthermore, in the multi-stage ultrapure water absorption step, the purified hydrogen chloride gas is introduced into a four-stage quartz glass falling film absorption tower. The first-stage falling film absorption tower performs pre-absorption, where the purified hydrogen chloride gas is countercurrently contacted with ultrapure water with a resistivity ≥18.2 MΩ·cm for deep absorption. During absorption, the liquid-to-gas ratio (L / G) is controlled at 1:1.5, the temperature at 30-35℃, and the residence time at 8-10 seconds, yielding dilute hydrochloric acid with a concentration of 20-25%. A portion of the unabsorbed gas phase enters the second-stage falling film absorption tower. The first-stage falling film absorber absorbs the gas phase from the first-stage tower outlet, controlling the liquid-to-gas ratio (L / G) with ultrapure water at 1:1.2, with the temperature controlled at 35-38℃ and the falling film flow rate at 1.2-1.5 m / s, yielding hydrochloric acid with a concentration of 30-32%. A portion of the unabsorbed gas phase enters the third-stage falling film absorber. The third-stage falling film absorber then absorbs the gas phase from the second-stage tower outlet, controlling the liquid-to-gas ratio (L / G) with ultrapure water at 1:0.8, with the temperature controlled at 38-40℃ and the nitrogen protection flow rate controlled at 2-3 Nm³. 3 The process yields high-concentration hydrochloric acid of 35-36% per hour, with residual HCl <5% in the outlet gas phase. This hydrochloric acid then enters a four-stage falling film absorber for absorption. In the four-stage falling film absorber, the outlet gas phase from the three-stage tower is absorbed by ultrapure water at a controlled liquid-to-gas ratio (L / G) of 1:0.5, with the temperature controlled at 40±1℃. This produces electronic-grade hydrochloric acid with a concentration of 36.5-37.0%, with unabsorbed gas <0.1% in the tail gas. This tail gas is then sent to a hydrogen chloride absorber.

[0008] Preferably, the dilute hydrochloric acid with a concentration of 20-25%, the hydrochloric acid with a concentration of 30-32%, and the high-concentration hydrochloric acid with a concentration of 35-36% are used for recycling in the production of general industrial-grade hydrochloric acid.

[0009] Furthermore, the dilute sulfuric acid concentration and regeneration system includes the following steps:

[0010] The concentration produced in step one is 60-65%, containing Ca. 2 / Mg 250-100ppm dilute sulfuric acid is introduced into the preheater of the concentration regeneration system, the temperature is controlled at 70-75 DEG C to avoid local boiling, the preheating medium is 0.3MPa low pressure saturated steam, the flow rate is controlled at 2.5-3.0m 3 / h; the preheated dilute sulfuric acid is pumped into the vacuum evaporator, the operating pressure is -0.085±0.005MPa, the boiling point is reduced to avoid decomposition of sulfuric acid, the internal evaporation temperature of the feed liquid is controlled at 85±2 DEG C to prevent the generation of SO gas, high purity nitrogen is introduced during the period, the evaporation intensity is 25-30kg / (m 2 ·h) to ensure the concentration efficiency, the concentration endpoint is judged by using an online densimeter for real-time monitoring, the density is ≥1.84g / cm 3 (98%), the evaporation vapor is obtained; the evaporation vapor is introduced into the crystallization reaction kettle, the residence time is 45-60 minutes, the stirring rate is 30-40rpm, the temperature is reduced by using a gradient type from 90 DEG C to 70 DEG C, a solid-liquid mixture is obtained and then subjected to solid-liquid separation by a horizontal screw centrifuge, regenerated concentrated sulfuric acid with a concentration of ≥98% is obtained, the condensate water generated in the concentration process is introduced into the circulating water system of the plant to adjust the PH of the circulating water, a small amount of calcium sulfate, magnesium sulfate waste residue can be transported to the primary brine process, and after pressure filtration by a plate and frame filter, the residue is treated together with salt mud.

[0011] Preferably, the preparation process of the 18M super pure water system is that: the desalted water is pumped into an ultrafiltration system after the colloids and microorganisms are intercepted by a filter membrane with a pore size of 0.01um, after first reverse osmosis and second reverse osmosis, after an EDI module, it is sent to a pure water tank for standby, and the super pure water is used for water replenishment of an absorption system and a cold cutting system.

[0012] Further, the cooling water system uses pure water as the cooling circulating water of the process device, a closed circulation cooling water system is configured, and the closed circulation cooling water system is used as a waste heat conducting medium for device cooling, and after heat exchange, the cooling water is cooled by a closed cooling tower and then recycled after indirect heat exchange by frozen brine.

[0013] Preferably, the protection gas system uses nitrogen gas after rectification and purification from a nitrogen gas pipe network, and the purified nitrogen gas is supplied to each gas using point of the process.

[0014] The beneficial effects of the application are embodied in:

[0015] The high-efficiency purification of electronic-grade hydrochloric acid is realized by accurate control of process parameters, such as a terminal absorption temperature of 40±1 ℃; the overall efficiency of the system is improved by cooperation of subsystems, such as the use of ultrapure water for absorption and cooling; the production cost is reduced by about 42% by recycling resources, such as sulfuric acid regeneration and wastewater reuse; the removal rate of metal impurities is increased by 90% by using concentrated sulfuric acid purification and impurity removal technology, so that the photovoltaic-grade hydrochloric acid standard is met; the product quality is ensured by using nitrogen protection materials and 18 MΩ ultrapure water for absorption; the value of chlorine resources is improved by directly using high-purity hydrogen chloride gas (90-96%) produced by a hydrogen chloride synthesis device; and the process flow does not exist heating vaporization process, energy consumption is saved, production cost is reduced, and the process is clean and environmentally friendly, without new pollution factors. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the process flow chart of the high-yield electronic-grade hydrochloric acid purification method based on heating provided by the application;

[0017] Figure 2 is the multi-stage ultrapure water absorption process flow chart provided by the application. DETAILED DESCRIPTION

[0018] The technical solutions of the application will be described clearly and completely in the embodiments combined with the drawings. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0019] Example 1

[0020] A high-yield electronic-grade hydrochloric acid purification method based on heating, which comprises five subsystems: a hydrochloric acid purification and absorption system, a dilute sulfuric acid concentration and regeneration system, an 18 MΩ ultrapure water system, a protective gas system, and a cooling water system.

[0021] The hydrochloric acid purification and absorption system comprises the following steps:

[0022] Step one: hydrogen chloride gas concentrated sulfuric acid purification

[0023] S1: raw material preparation, using hydrogen chloride gas byproduct of a caustic soda device, hydrogen chloride purity 92%, temperature control at 35℃;

[0024] S2: through a packed 98wt% concentrated sulfuric acid washing tower, gas velocity control 0.4 m / s, remove water and part of metal ions in the gas, sulfuric acid temperature maintained at 40±2℃, sulfuric acid temperature controlled by a cooling water system, residence time 18 seconds, remove Fe, Cl2, organic matter and other impurities, and obtain purified hydrogen chloride gas, wherein the total amount of metal impurities is 450 ppb;

[0025] Step two: multi-stage ultra-pure water absorption

[0026] The purified hydrogen chloride gas is introduced into a four-stage quartz glass falling film absorption tower,

[0027] S1: primary falling film absorption tower pre-absorption, purified hydrogen chloride gas is contacted with 18.5 MΩ·cm resistivity ultra-pure water in countercurrent, deep absorption is carried out, during the absorption process, the liquid-gas ratio (L / G) is controlled to be 1:1.5, the temperature is controlled to be 32℃, the residence time is 9 seconds, a dilute hydrochloric acid with a concentration of 22% is obtained, and part of the unabsorbed gas phase enters the secondary falling film absorption tower;

[0028] S2: secondary falling film absorption tower absorption, the gas phase at the outlet of the primary tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:1.2, the temperature is controlled to be 36℃, the falling film flow rate is 1.3 m / s, a hydrochloric acid with a concentration of 31% is obtained, and part of the unabsorbed gas phase enters the tertiary falling film absorption tower;

[0029] S3: tertiary falling film absorption tower absorption, the gas phase at the outlet of the secondary tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:0.8, the temperature is controlled to be 39℃, the nitrogen protection flow rate is controlled to be 2.5 Nm 3 / h, a high-concentration hydrochloric acid with a concentration of 35.5% is obtained, the residual HCl in the outlet gas phase is 4.5%, and it enters the four-stage falling film absorption tower for absorption;

[0030] S4: four-stage falling film absorption tower absorption, the gas phase at the outlet of the tertiary tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:0.5, the temperature is controlled to be 40±1℃, an electronic-grade hydrochloric acid with a concentration of 36.8% is obtained, the unabsorbed gas in the tail gas is 0.08%, and it is sent to the hydrogen chloride absorption device;

[0031] The dilute sulfuric acid generated in step one is introduced into the concentration and regeneration system for concentration and regeneration, and the specific steps are as follows:

[0032] S1: the dilute sulfuric acid generated in step one has a concentration of 62%, contains Ca 2 / Mg 2 75ppm, and is preheated in the preheater of the concentration and regeneration system, the temperature is controlled to be 72℃ to avoid local boiling, the preheating medium is 0.3 MPa low-pressure saturated steam, and the flow rate is controlled to be 2.8 m 3 / h;

[0033] S2: after preheating, the dilute sulfuric acid is pumped into the vacuum evaporator, the operating pressure is-0.085±0.005 MPa, the boiling point is reduced to avoid decomposition of sulfuric acid, the internal evaporation temperature of the feed liquid is controlled to be 85±2℃ to prevent the generation of SO3 gas, high-purity nitrogen is introduced during the period, and the evaporation intensity is 27 kg / (m 2• h) guaranteeing the concentration efficiency, the end point of concentration is judged by on-line density meter, density 1.84 g / cm 3 (98%), to obtain the evaporation vapor;

[0034] S3: the evaporation vapor is introduced into the crystallization reactor, the residence time is 50 minutes, the stirring rate is 35 rpm, the temperature is decreased by gradient from 90°C to 70°C, to obtain a solid-liquid mixture which is separated by a horizontal screw centrifuge to obtain regenerated concentrated sulfuric acid with a concentration of 98.5%, the condensate water produced in the concentration process is introduced into the circulating water system of the plant to adjust the pH of the circulating water, and a small amount of calcium sulfate and magnesium sulfate waste residue can be transported to the primary brine process and treated together with the salt mud after pressure filtration by a plate and frame filter.

[0035] 18 MΩ ultra-pure water system preparation process: desalted water is pumped into the ultrafiltration system after passing through a filter membrane with a pore size of 0.01 μm to intercept colloids and microorganisms, and after first and second reverse osmosis and EDI module, it is sent to the pure water tank for standby, and the ultra-pure water is used for water replenishment in the absorption system and cold cutting system.

[0036] The cooling water system uses pure water as the cooling circulating water of the process device, configures a closed circulation cooling water system, and uses it as a waste heat conducting medium for device cooling. After heat exchange, the cooling water is first cooled by a closed cooling tower, and then indirectly exchanges heat with frozen brine for recycling.

[0037] The protective gas system uses nitrogen gas from the nitrogen gas pipe network after purification, and the purified nitrogen gas is used by each gas point in the process. The first, second, third and fourth falling film absorption towers all introduce purified nitrogen gas as protective gas, and the purity of the protective gas is: dew point -72°C, O2 content 0.08 ppm.

[0038] In this embodiment, dilute hydrochloric acid with a concentration of 22%, hydrochloric acid with a concentration of 31%, and high-concentration hydrochloric acid with a concentration of 35.5% are used for general industrial-grade hydrochloric acid production and recycling. Through this recycling mode, the resource utilization efficiency of the whole system is improved, the waste liquid discharge is reduced, and clean production is realized.

[0039] Example Two

[0040] A heating-based high-yield electronic-grade hydrochloric acid purification method, which includes five subsystems: hydrochloric acid purification and absorption system, dilute sulfuric acid concentration and regeneration system, 18 MΩ ultra-pure water system, protective gas system, and cooling water system.

[0041] The hydrochloric acid purification and absorption system includes the following steps:

[0042] Step one: purification of hydrogen chloride gas and concentrated sulfuric acid

[0043] S1: raw material preparation, using hydrogen chloride gas byproduct of caustic soda device, hydrogen chloride purity 95%, temperature control at 38℃;

[0044] S2: by filling 98wt% concentrated sulfuric acid washing tower, gas velocity control 0.35m / s washing gas, remove water and part of metal ions in the gas, sulfuric acid temperature maintained at 40±2℃, sulfuric acid temperature control by cooling water system, residence time 20 seconds, remove Fe, Cl2, organic matter and other impurities, get purified hydrogen chloride gas, wherein the total amount of metal impurities is 420ppb;

[0045] Step two: multi-stage ultra-pure water absorption

[0046] The purified hydrogen chloride gas is introduced into the four-stage quartz glass falling film absorption tower,

[0047] S1: pre-absorption of the first-stage falling film absorption tower, purified hydrogen chloride gas is contacted with 18.3MΩ·cm resistivity ultra-pure water countercurrently for deep absorption, during the absorption process, the liquid-gas ratio (L / G) is controlled at 1:1.5, the temperature is controlled at 33℃, and the residence time is 8.5 seconds, obtaining 23% concentration of dilute hydrochloric acid, part of the unabsorbed gas phase enters the second-stage falling film absorption tower;

[0048] S2: absorption of the second-stage falling film absorption tower, the gas phase at the outlet of the first-stage tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:1.2, the temperature is controlled at 37℃, and the falling film flow rate is 1.4m / s, obtaining 30.5% concentration of hydrochloric acid, part of the unabsorbed gas phase enters the third-stage falling film absorption tower;

[0049] S3: absorption of the third-stage falling film absorption tower, the gas phase at the outlet of the second-stage tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:0.8, the temperature is controlled at 38.5℃, the nitrogen protection flow rate is controlled at 2.8Nm 3 / h, obtaining 35.8% concentration of high-concentration hydrochloric acid, the residual HCl in the outlet gas phase is 4.2%, which enters the fourth-stage falling film absorption tower for absorption;

[0050] S4: absorption of the fourth-stage falling film absorption tower, the gas phase at the outlet of the third-stage tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:0.5, the temperature is controlled at 40±1℃, obtaining 36.9% concentration of electronic-grade hydrochloric acid, the unabsorbed gas in the tail gas is 0.06%, which is sent to the hydrogen chloride absorption device;

[0051] The dilute sulfuric acid generated in step one is introduced into the concentration and regeneration system for concentration and regeneration, the specific steps are as follows:

[0052] S1: the concentration of the dilute sulfuric acid generated in step one is 63%, containing Ca 2 / Mg 265ppm dilute sulfuric acid is preheated by the preheater of the concentration regeneration system, the temperature is controlled at 73°C to avoid local boiling, the preheating medium is 0.3MPa low pressure saturated steam, the flow rate is controlled at 2.7m 3 / h;

[0053] S2: the preheated dilute sulfuric acid is pumped into the vacuum evaporator, the operating pressure is -0.085±0.005MPa, the boiling point is lowered to avoid decomposition of sulfuric acid, the internal evaporation temperature of the feed liquid is controlled at 85±2°C to prevent the generation of SO3 gas, high purity nitrogen is introduced during the period, the evaporation intensity is 28kg / (m 2 ·h) to ensure the concentration efficiency, the concentration endpoint is determined by real-time monitoring of the online densimeter, the density is 1.85g / cm 3 (98.2%), and the evaporation vapor is obtained;

[0054] S3: the evaporation vapor is introduced into the crystallization reactor, the residence time is 55 minutes, the stirring rate is 32rpm, the temperature is lowered by gradient from 90°C to 70°C, a solid-liquid mixture is obtained and then subjected to solid-liquid separation by a horizontal screw centrifuge, to obtain regenerated concentrated sulfuric acid with a concentration of 98.8%, the condensate water generated in the concentration process is introduced into the circulating water system of the plant to adjust the pH of the circulating water, a small amount of waste calcium sulfate and magnesium sulfate residue can be transported to the primary brine process, and after pressure filtration by a plate and frame filter, it is treated together with the salt mud.

[0055] The preparation process of the 18Megaohm ultra-pure water system is as follows: the desalted water is pumped into the ultrafiltration system after passing through a filter membrane with a pore size of 0.01μm to intercept colloids and microorganisms, after first and second reverse osmosis, and after an EDI module, it is sent to a pure water tank for standby, and the ultra-pure water is used for water replenishment in the absorption system and the cold cutting system.

[0056] The cooling water system uses pure water as the cooling circulating water of the process device, configures a closed circulation cooling water system, and uses it as a waste heat conducting medium for device cooling, and after heat exchange, the cooling water is first cooled by a closed cooling tower, and then indirectly exchanges heat with frozen brine for recycling.

[0057] The protective gas system uses nitrogen gas from the nitrogen gas pipe network after rectification and purification, and the purified nitrogen gas is supplied to each gas using point of the process. The first, second, third and fourth falling film absorption towers all introduce purified nitrogen gas as protective gas, and the purity of the protective gas is: dew point -71°C, O2 content 0.09ppm.

[0058] In this embodiment, dilute hydrochloric acid with a concentration of 23%, hydrochloric acid with a concentration of 30.5%, and high concentration hydrochloric acid with a concentration of 35.8% are used for general industrial grade hydrochloric acid production and recycling.

[0059] Example Three

[0060] A purification method of high-yield electronic grade hydrochloric acid based on heating, which comprises five subsystems: hydrochloric acid purification and absorption system, dilute sulfuric acid concentration and regeneration system, 18 mega-ohm ultra-pure water system, protective gas system and cooling water system.

[0061] The hydrochloric acid purification and absorption system comprises the following steps:

[0062] Step one: hydrogen chloride gas concentrated sulfuric acid purification

[0063] S1: raw material preparation, using hydrogen chloride gas byproduct of a caustic soda device, hydrogen chloride purity 90%, temperature controlled at 40°C;

[0064] S2: through the packing of 98wt% concentrated sulfuric acid washing tower, gas velocity control 0.5m / s gas washing, remove water and part of metal ions in the gas, sulfuric acid temperature maintained at 40±2°C, sulfuric acid temperature controlled by cooling water system, residence time 15 seconds, remove Fe, Cl2, organic matter and other impurities, obtain purified hydrogen chloride gas, wherein the total amount of metal impurities is 490ppb;

[0065] Step two: multi-stage ultra-pure water absorption

[0066] The purified hydrogen chloride gas is introduced into a four-stage quartz glass falling film absorption tower,

[0067] S1: first-stage falling film absorption tower pre-absorption, purified hydrogen chloride gas is countercurrently contacted with 18.2MΩ·cm resistivity ultra-pure water for deep absorption, during the absorption process, the liquid-gas ratio (L / G) is controlled at 1:1.5, the temperature is controlled at 30°C, and the residence time is 10 seconds, obtaining 20% concentration dilute hydrochloric acid, part of the unabsorbed gas phase enters the second-stage falling film absorption tower;

[0068] S2: second-stage falling film absorption tower absorption, the gas phase at the outlet of the first-stage tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:1.2, the temperature is controlled at 35°C, and the falling film flow rate is 1.2m / s, obtaining 32% concentration hydrochloric acid, part of the unabsorbed gas phase enters the third-stage falling film absorption tower;

[0069] S3: third-stage falling film absorption tower absorption, the gas phase at the outlet of the second-stage tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:0.8, the temperature is controlled at 40°C, the nitrogen protection flow rate is controlled at 3Nm 3 / h, obtaining 36% concentration high-concentration hydrochloric acid, the residual HCl in the outlet gas phase is 4.8%, which enters the fourth-stage falling film absorption tower for absorption;

[0070] S4: four-stage falling film absorption tower absorption, the three-stage tower outlet gas phase and ultra-pure water control liquid gas ratio (L / G) 1:0.5 absorption, temperature control for 40±1℃, get the concentration of 37.0% electronic grade hydrochloric acid, tail gas not absorbed gas is 0.05%, sent into the hydrogen chloride absorption device;

[0071] The dilute sulfuric acid generated in step one is passed into the concentration regeneration system for concentration regeneration, and the specific steps are as follows:

[0072] S1: the dilute sulfuric acid generated in step one has a concentration of 60%, contains Ca 2 / Mg 2 100ppm dilute sulfuric acid is preheated in the preheater of the concentration regeneration system, the temperature is controlled at 70℃ to avoid local boiling, the preheating medium is 0.3MPa low-pressure saturated steam, and the flow rate is controlled at 2.5m 3 / h;

[0073] S2: after preheating, the dilute sulfuric acid is pumped into the vacuum evaporator, the operating pressure is-0.085±0.005MPa, the boiling point is reduced to avoid decomposition of sulfuric acid, the internal evaporation temperature of the feed liquid is controlled at 85±2℃ to prevent the generation of SO3 gas, high-purity nitrogen is introduced during the period, the evaporation intensity is 25kg / (m 2 ·h) to ensure the concentration efficiency, the concentration endpoint is judged by real-time monitoring of the online densimeter, the density is 1.86g / cm 3 (98.5%), and the evaporation steam is obtained;

[0074] S3: the evaporation steam is introduced into the crystallization reactor, the residence time is 60 minutes, the stirring rate is 30rpm, the temperature is reduced by gradient from 90℃ to 70℃, a solid-liquid mixture is obtained, and then solid-liquid separation is performed by a horizontal screw centrifuge to obtain regenerated concentrated sulfuric acid with a concentration of 99%, the condensate generated in the concentration process is introduced into the circulating water system of the factory to adjust the PH of the circulating water, a small amount of calcium sulfate and magnesium sulfate waste residue can be transported to the primary brine process, and after pressure filtration by a plate and frame filter, it is treated together with salt mud.

[0075] The preparation process of the 18MΩ ultra-pure water system is: the desalted water is pumped into the ultrafiltration system after being intercepted by a filter membrane with a pore size of 0.01μm to remove colloids and microorganisms, after one-stage reverse osmosis and two-stage reverse osmosis, and after an EDI module, it is sent to a pure water tank for standby, and the ultra-pure water is used for water replenishment in the absorption system and the cold cutting system.

[0076] The cooling water system uses pure water as the cooling circulating water of the process device, configures a closed circulation cooling water system, and uses it as a waste heat conducting medium for cooling of the device, and after heat exchange, the cooling water is first cooled by a closed cooling tower, and then indirectly exchanges heat with frozen brine for recycling.

[0077] The protective gas system uses a self-nitrogen pipe network to pass the rectified nitrogen, and the purified nitrogen is used in each gas point of the process. The first, second, third and fourth falling film absorption towers are all connected with the purified nitrogen as protective gas, and the purity of the protective gas is: dew point -70℃, O2 content 0.1ppm.

[0078] In the embodiment, the dilute hydrochloric acid with a concentration of 20%, the hydrochloric acid with a concentration of 32% and the high-concentration hydrochloric acid with a concentration of 36% are used for the general industrial-grade hydrochloric acid production and recycling.

[0079] Embodiment four

[0080] A heating-based purification method of high-yield electronic-grade hydrochloric acid, which comprises five subsystems: a hydrochloric acid purification and absorption system, a dilute sulfuric acid concentration and regeneration system, an 18 mega-ohm ultra-pure water system, a protective gas system and a cooling water system.

[0081] The hydrochloric acid purification and absorption system comprises the following steps:

[0082] Step one: hydrogen chloride gas concentrated sulfuric acid purification

[0083] S1: raw material preparation, using hydrogen chloride gas byproduct of a caustic soda device, hydrogen chloride purity 96%, temperature control at 37℃;

[0084] S2: through a washing tower filled with 98wt% concentrated sulfuric acid, gas velocity control 0.3m / s, remove water and part of metal ions in the gas, sulfuric acid temperature maintained at 40±2℃, sulfuric acid temperature control by a cooling water system, residence time 22 seconds, remove Fe, Cl2, organic matter and other impurities, obtain purified hydrogen chloride gas, wherein the total amount of metal impurities is 380ppb;

[0085] Step two: multi-stage ultra-pure water absorption

[0086] Pass the purified hydrogen chloride gas into a four-stage quartz glass falling film absorption tower,

[0087] S1: first-stage falling film absorption tower pre-absorption, the purified hydrogen chloride gas is countercurrently contacted with ultra-pure water with a resistivity of 18.6MΩ·cm for deep absorption, in the absorption process, the liquid-gas ratio (L / G) is controlled to be 1:1.5, the temperature is controlled to be 34℃, and the residence time is 8 seconds, to obtain dilute hydrochloric acid with a concentration of 25%, and part of the unabsorbed gas phase enters the second-stage falling film absorption tower;

[0088] S2: second-stage falling film absorption tower absorption, the gas phase at the outlet of the first-stage tower is absorbed with ultra-pure water with a liquid-gas ratio (L / G) of 1:1.2, the temperature is controlled to be 38℃, and the falling film flow rate is 1.5m / s, to obtain hydrochloric acid with a concentration of 30%, and part of the unabsorbed gas phase enters the third-stage falling film absorption tower;

[0089] S3: absorption in a third falling-film absorption tower, absorption of the gas phase at the outlet of the second tower with ultrapure water at a liquid-gas ratio (L / G) of 1:0.8, temperature control at 39.5°C, nitrogen protection flow rate controlled at 2 Nm 3 / h, to obtain high-concentration hydrochloric acid with a concentration of 35%, residual HCl in the outlet gas phase being 4%, which is absorbed in a fourth falling-film absorption tower;

[0090] S4: absorption in a fourth falling-film absorption tower, absorption of the gas phase at the outlet of the third tower with ultrapure water at a liquid-gas ratio (L / G) of 1:0.5, temperature control at 40±1°C, to obtain electronic-grade hydrochloric acid with a concentration of 36.5%, unabsorbed gas in the tail gas being 0.09%, which is sent to a hydrogen chloride absorption device;

[0091] The dilute sulfuric acid generated in step one is fed into a concentration and regeneration system for concentration and regeneration, and the specific steps are as follows:

[0092] S1: the dilute sulfuric acid generated in step one has a concentration of 65% and contains Ca 2 / Mg 2 50ppm, the dilute sulfuric acid is preheated in a preheater of the concentration and regeneration system, the temperature is controlled at 75°C to avoid local boiling, the preheating medium is 0.3 MPa low-pressure saturated steam, and the flow rate is controlled at 3.0 m 3 / h;

[0093] S2: after preheating, the dilute sulfuric acid is pumped into a vacuum evaporator, the operating pressure is-0.085±0.005 MPa to reduce the boiling point and avoid decomposition of sulfuric acid, the internal evaporation temperature of the feed liquid is controlled at 85±2°C to prevent the generation of SO3 gas, high-purity nitrogen is fed in during the period, the evaporation intensity is 30 kg / (m 2 ·h) to ensure the concentration efficiency, the concentration endpoint is judged by real-time monitoring of an online densimeter, the density is 1.84 g / cm 3 (98%), and the evaporation steam is obtained;

[0094] S3: the evaporation steam is fed into a crystallization reaction kettle, the residence time is 45 minutes, the stirring rate is 40 rpm, the temperature is lowered in a gradient mode from 90°C to 70°C, a solid-liquid mixture is obtained, and then solid-liquid separation is performed on the solid-liquid mixture by using a horizontal screw centrifuge, to obtain regenerated concentrated sulfuric acid with a concentration of 98%, the condensate water generated in the concentration process is fed into a circulating water system of the factory to adjust the PH of the circulating water, a small amount of waste calcium sulfate and magnesium sulfate slag can be transported to a primary brine process, and after pressure filtration by using a plate-and-frame filter, the waste calcium sulfate and magnesium sulfate slag are treated together with salt mud.

[0095] The preparation process of the 18 MΩ ultrapure water system is as follows: the desalted water is filtered by using a filter membrane with a pore size of 0.01 μm to intercept colloids and microorganisms, is pumped into an ultrafiltration system, is subjected to primary reverse osmosis and secondary reverse osmosis, is subjected to an EDI module, and is then sent to a pure water tank for standby, and the ultrapure water is used for water replenishment in an absorption system and a cold cutting system.

[0096] The cooling water system uses pure water to cool the circulating water of the process device, configures a closed circulating cooling water system, uses the device cooling waste heat as a heat conduction medium, and after heat exchange, the cooling water is first cooled by a closed cooling tower, and then is indirectly heat exchanged by frozen brine before being recycled.

[0097] The protective gas system uses nitrogen from a nitrogen pipe network after rectification and purification, and the purified nitrogen is supplied to each gas point in the process. The first, second, third and fourth falling film absorption towers are all connected to the purified nitrogen as protective gas, and the purity of the protective gas is: dew point -70.5℃, O2 content 0.095ppm.

[0098] In the present embodiment, dilute hydrochloric acid with a concentration of 25%, hydrochloric acid with a concentration of 30% and high-concentration hydrochloric acid with a concentration of 35% are used for general industrial-grade hydrochloric acid production and recycling.

[0099] It should be noted that example one, example two, example three and example four are all one kind of purification method of high-yield electronic-grade hydrochloric acid based on heating.

[0100] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for purifying high-yield electronic-grade hydrochloric acid based on heating, characterized in that... It includes five subsystems: hydrochloric acid purification and absorption system, dilute sulfuric acid concentration and regeneration system, 18 megohm ultrapure water system, protective gas system, and cooling water system. The hydrochloric acid purification and absorption system includes the following steps: Step 1: Purification of hydrogen chloride gas with concentrated sulfuric acid S1: Raw material preparation: Hydrogen chloride gas, a byproduct of the caustic soda production unit, is used. The hydrogen chloride purity is 90-96%, and the temperature is ≤40℃. S2: A scrubbing tower filled with 98wt% concentrated sulfuric acid is used to remove moisture and some metal ions from the gas through a controlled gas velocity of 0.3-0.5 m / s. The sulfuric acid temperature is maintained at 40±2℃, and the sulfuric acid is cooled by a cooling water system. The residence time is ≥15 seconds. Impurities such as organic matter are removed to obtain purified hydrogen chloride gas, in which the total amount of metal impurities is <500ppb; Step 2: Multi-stage ultrapure water absorption The purified hydrogen chloride gas is then passed into a four-stage quartz glass falling film absorption tower. S1: Pre-absorption in the primary falling film absorption tower involves countercurrent contact between purified hydrogen chloride gas and ultrapure water with a resistivity ≥18.2 MΩ·cm for deep absorption. During absorption, the liquid-to-gas ratio (L / G) is controlled at 1:1.5, the temperature at 30-35℃, and the residence time at 8-10 seconds, yielding dilute hydrochloric acid with a concentration of 20-25%. A portion of the unabsorbed gas phase enters the secondary falling film absorption tower. S2: The secondary falling film absorber absorbs the gas phase from the primary absorber outlet and ultrapure water at a controlled liquid-to-gas ratio (L / G) of 1:1.

2. The temperature is controlled at 35-38℃, and the falling film flow rate is 1.2-1.5 m / s, yielding hydrochloric acid with a concentration of 30-32%. A portion of the unabsorbed gas phase enters the tertiary falling film absorber. S3: The three-stage falling film absorber absorbs the gas phase from the outlet of the second-stage absorber with ultrapure water at a controlled liquid-to-gas ratio (L / G) of 1:0.

8. The temperature is controlled at 38-40℃, and the nitrogen protection flow rate is controlled at 2-3 Nm³ / h. This yields high-concentration hydrochloric acid with a concentration of 35-36%, and the residual HCl in the outlet gas phase is <5%. This then enters the fourth-stage falling film absorber for further absorption. S4: The four-stage falling film absorption tower absorbs the gas phase from the outlet of the three-stage tower and ultrapure water at a controlled liquid-to-gas ratio (L / G) of 1:0.5, with the temperature controlled at 40±1℃, to obtain electronic-grade hydrochloric acid with a concentration of 36.5-37.0%. The unabsorbed gas in the tail gas is <0.1%, which is then sent to the hydrogen chloride absorption unit. The dilute sulfuric acid produced in step one is passed into a concentration and regeneration system for concentration and regeneration. The primary, secondary, tertiary, and quaternary falling film absorption towers all use purified nitrogen as a protective gas. The purity of the protective gas is: dew point ≤ -70℃. <0.1ppm.

2. The purification method for high-yield electronic-grade hydrochloric acid based on heating according to claim 1, characterized in that, The dilute hydrochloric acid with a concentration of 20-25%, the hydrochloric acid with a concentration of 30-32%, and the high-concentration hydrochloric acid with a concentration of 35-36% are used for recycling in the production of general industrial-grade hydrochloric acid.

3. The purification method for high-yield electronic-grade hydrochloric acid based on heating according to claim 1, characterized in that, The dilute sulfuric acid concentration and regeneration system includes the following steps: S1: The 60-65% concentration dilute sulfuric acid produced in step one, containing 50-100 ppm Ca² / Mg², is preheated in the preheater of the concentration and regeneration system. The temperature is controlled at 70-75℃ to avoid local boiling. The preheating medium is 0.3MPa low-pressure saturated steam, and the flow rate is controlled at 2.5-3.0 m³ / h. S2: After preheating, dilute sulfuric acid is pumped into the vacuum evaporator at an operating pressure of -0.085±0.005MPa to lower the boiling point and prevent sulfuric acid decomposition. The internal evaporation temperature of the feed liquid is controlled at 85±2℃ to prevent the generation of SO3 gas. High-purity nitrogen is introduced during this process. The evaporation rate is 25-30 kg / (m²·h) to ensure concentration efficiency. The concentration endpoint is determined by real-time monitoring using an online density meter. When the density is ≥1.84 g / cm³ (98%), the evaporated vapor is obtained. S3: The evaporated steam is introduced into the crystallization reactor, the residence time is 45-60 minutes, the stirring speed is 30-40 rpm, and the temperature is gradually reduced from 90℃ to 70℃ to obtain a solid-liquid mixture. The mixture is then separated by a horizontal screw centrifuge to obtain regenerated concentrated sulfuric acid with a concentration of ≥98%. The condensate generated during the concentration process enters the factory's circulating water system to adjust the pH of the circulating water. A small amount of calcium sulfate and magnesium sulfate waste residue can be transported to the primary brine process. After being filtered by a plate and frame filter press, it is treated together with the salt mud.

4. The purification method for high-yield electronic-grade hydrochloric acid based on heating according to claim 1, characterized in that, The preparation process of the 18 megohm ultrapure water system is as follows: desalinated water is filtered through a 0.01μm pore size filter membrane to retain colloids and microorganisms, and then pumped into the ultrafiltration system. After passing through a first-stage reverse osmosis and a second-stage reverse osmosis, it is sent to the pure water tank for standby after passing through the EDI module. The ultrapure water is used to replenish water for the absorption system and the cold cutting system.

5. The purification method for high-yield electronic-grade hydrochloric acid based on heating according to claim 1, characterized in that, The cooling water system uses pure water as the circulating cooling water for the process unit. It is configured as a closed-loop circulating cooling water system and is used as a heat transfer medium for cooling waste heat of the unit. After heat exchange, the cooling water is first cooled by a closed cooling tower, and then indirectly cooled by chilled brine before being recycled.

6. The purification method for high-yield electronic-grade hydrochloric acid based on heating according to claim 1, characterized in that, The protective gas system uses nitrogen purified by distillation from a nitrogen pipeline network, which is then supplied to various gas-using points in this process.

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