CN-121971867-A - Sulfur-fluorine mixed acid evaporation concentration separation system and evaporation concentration separation method

CN121971867ACN 121971867 ACN121971867 ACN 121971867ACN-121971867-A

Abstract

The invention discloses a sulfur-fluorine mixed acid evaporation concentration separation system which comprises a mixed acid separation concentration device, a sulfuric acid defluorination device, a sulfuric acid concentration device and a sulfuric acid concentration device, wherein the mixed acid separation concentration device is used for heating, concentrating and separating fluorine-sulfur mixed acid, preparing hydrofluoric acid after cooling obtained hydrofluoric acid steam, the obtained low-fluorine sulfuric acid is conveyed to a sulfuric acid defluorination device through a pipeline, the sulfuric acid defluorination device is used for heating and separating the low-fluorine sulfuric acid, removing fluorine-containing substances in the low-fluorine sulfuric acid, the obtained sulfuric acid is conveyed to the sulfuric acid concentration device through the pipeline, the obtained hydrofluoric acid steam is cooled and then is used for preparing hydrofluoric acid, the obtained concentrated sulfuric acid is returned to the mixed acid separation concentration device, and production water containing trace sulfuric acid is obtained. The invention also discloses a sulfur-fluorine mixed acid evaporation concentration separation method. The invention can obtain high-concentration concentrated sulfuric acid from the low-concentration sulfur-fluorine mixed acid in the evaporation concentration process, thereby realizing the comprehensive utilization of F, S resources.

Inventors

HAO GAOHUI
LI LU
SANG XIAOYUN
LIU LINGYUN
WANG YONGLI
ZHAO ZHANFENG
LI JUNZHENG
CAO SHENGBIAO

Assignees

包头华美稀土高科有限公司
中国北方稀土（集团）高科技股份有限公司

Dates

Publication Date: 20260505
Application Date: 20251210

Claims (10)

1. A sulfur and fluorine mixed acid evaporation concentration separation system, which is characterized by comprising: the mixed acid separation and concentration device is used for heating, concentrating and separating the fluorine-sulfur mixed acid, cooling the obtained hydrofluoric acid steam to prepare hydrofluoric acid, and conveying the obtained low-fluorine sulfuric acid to the sulfuric acid defluorination device through a pipeline; The sulfuric acid defluorination device is used for heating and separating the low-fluorine sulfuric acid to remove fluorine-containing substances in the low-fluorine sulfuric acid, the obtained sulfuric acid is conveyed to the sulfuric acid concentration device through a pipeline, and the obtained hydrofluoric acid steam is cooled to prepare hydrofluoric acid; and the sulfuric acid concentration device is used for heating and concentrating sulfuric acid, and the obtained concentrated sulfuric acid is recycled to the mixed acid separation concentration device to obtain production water containing trace sulfuric acid.
2. The sulfur-fluorine mixed acid evaporation concentration separation system of claim 1, wherein the mixed acid separation concentration device comprises a first-stage separator, a first-stage heat exchanger, a second-stage separator, a second-stage heat exchanger and a fluorine acid cooler, wherein circulation ports of the first-stage separator and the first-stage heat exchanger are connected through circulation pipelines, liquid outlets of the first-stage separator are connected with liquid inlets of the second-stage separator through a liquid conveying pipeline, gas outlets of the first-stage separator are connected with gas inlets of the second-stage heat exchanger through a gas conveying pipeline, liquid outlets of the second-stage separator are connected with a sulfuric acid defluorination device through a liquid conveying pipeline, gas outlets of the second-stage separator are connected with the gas inlets of the fluorine acid cooler through a gas conveying pipeline, the fluorine acid cooler is used for cooling hydrofluoric acid vapor, and the outlet is connected with the fluorine acid collection device.
3. The sulfur-fluorine mixed acid evaporation concentration separation system of claim 2, wherein the sulfuric acid fluorine removal device comprises a fluorine removal separator, an acid heat exchanger and a steam cooler, wherein a liquid inlet of the fluorine removal separator is connected with a liquid outlet of the secondary separator through a liquid conveying pipeline, the liquid outlet of the fluorine removal separator is connected with the sulfuric acid concentration device through the liquid conveying pipeline, an air outlet of the fluorine removal separator is connected with the steam cooler through a gas conveying pipeline, and circulating ports of the fluorine removal separator and the steam cooler are connected through a circulating pipeline.
4. The sulfuric acid and fluorine mixed acid evaporation concentration separation system as claimed in claim 3, wherein the sulfuric acid concentration device comprises a concentration separator and a concentration heat exchanger, the circulation ports of the concentration separator and the concentration heat exchanger are connected through a circulation pipeline, the liquid inlet of the concentration heat exchanger is connected with the liquid outlet of the fluorine removal separator through a liquid delivery pipeline, and the liquid outlet of the concentration heat exchanger is connected with the primary separator through a liquid delivery pipeline.
5. The sulfur and fluorine mixed acid evaporation concentration separation system as claimed in claim 4, wherein the sulfuric acid defluorination device is selected from a defluorination chlorine tower, a cooling defluorination device, a defluorination filter, a sulfuric acid defluorination silicon column reactor, a stripping defluorination tower device, a sulfuric acid defluorination concentration device, an analytical tower defluorination device or a single-effect forced circulation evaporation device, the sulfuric acid concentration device is selected from a pot-type dilute sulfuric acid concentration device, a low-temperature multi-effect film distillation device, a three-effect concentrator, an MVR evaporator or a single-effect decompression evaporation device, and the fluoric acid cooler and the steam cooler are selected from a shell-and-tube acid cooler, a plate-type acid cooler, an anode and protection acid cooler, a tubular graphite acid cooler or an alloy acid cooler.
6. The sulfur and fluorine mixed acid evaporation concentration separation system as claimed in claim 4, wherein the primary separator, the secondary separator, the fluorine removal separator and the concentration separator are at least one of a thin film evaporator, a falling film evaporator, a rising film evaporator and a rectifying tower, and the primary heat exchanger, the acid heat exchanger and the concentration heat exchanger are at least one of a plate heat exchanger, a shell-and-tube heat exchanger, a sleeve heat exchanger, a spiral plate heat exchanger, a plate-fin heat exchanger, a heat pipe heat exchanger and a tube heat exchanger.
7. The sulfur and fluorine mixed acid evaporating, concentrating and separating method is characterized by comprising the following steps: the mixed acid separation and concentration device heats, concentrates and separates the mixed acid of fluorine and sulfur, the obtained hydrofluoric acid steam is cooled to prepare hydrofluoric acid, and the obtained low-fluorine sulfuric acid is conveyed to the sulfuric acid defluorination device through a pipeline; the sulfuric acid defluorination device heats and separates the low-fluorine sulfuric acid to remove fluorine-containing substances in the low-fluorine sulfuric acid, the obtained sulfuric acid is conveyed to the sulfuric acid concentration device through a pipeline, and the obtained hydrofluoric acid steam is cooled to prepare hydrofluoric acid; The sulfuric acid concentration device heats and concentrates sulfuric acid, the obtained concentrated sulfuric acid is recycled to the mixed acid separation concentration device, the production water containing trace sulfuric acid is obtained, and the production water is recycled to the circulating water system.
8. The method for evaporating, concentrating and separating sulfur and fluorine mixed acid according to claim 7, wherein the mixed acid is obtained by mixing low-concentration fluorine and sulfur mixed acid obtained by roasting tail gas of rare earth concentrate with concentrated sulfuric acid with concentration of 88% or more produced by a concentrated sulfuric acid device, the concentration of the mixed acid is 50% or more, the total acidity of the mixed acid is 22% -45%, the temperature of the mixed acid separating and concentrating device is controlled at 110-150 ℃, the concentration of sulfuric acid in the obtained low-fluorine sulfuric acid is 62% -68%, and the fluorine content of hydrofluoric acid is 1.2% -0.1%.
9. The method for evaporating, concentrating and separating sulfur and fluorine mixed acid according to claim 7, wherein the sulfuric acid fluorine removal device removes fluorine ions in low-fluorine sulfuric acid to obtain 62% -68% sulfuric acid and 8% -12% hydrofluoric acid calculated by HF, and the temperature of the acid fluorine removal device is 90-110 ℃.
10. The method for evaporating, concentrating and separating sulfur and fluorine mixed acid as recited in claim 7, wherein the concentration of concentrated sulfuric acid produced by the sulfuric acid concentrating device is more than or equal to 88%, and the working temperature is 180-210 ℃.

Description

Sulfur-fluorine mixed acid evaporation concentration separation system and evaporation concentration separation method Technical Field The invention belongs to the technical field of waste acid treatment, and particularly relates to a sulfur-fluorine mixed acid evaporation concentration separation system and an evaporation concentration separation method. Background Mixed gas containing fluorine, silicon and sulfur is generated in the roasting process of rare earth concentrate and concentrated sulfuric acid, the main components are HF, siF 4、SO2、SO3 and the like, the mixed gas is purified in a wet dust removal washing mode, mixed acid containing fluorine acid and sulfuric acid is enriched after purification, the main components of the mixed acid are HF, H 2SiF6、H2SO4、H2 O and the like, the conventional mixed acid treatment directly evaporates and concentrates the mixed acid in a heating mode according to the principle that the boiling points of sulfuric acid and HF are different, HF and H 2SiF6、H2 O form azeotropes in the mixed acid, HF and H 2SiF6 are evaporated with water synchronously in the evaporation process, so that high-concentration fluorine-containing mixed acid cannot be formed, the concentration of fluorine acid is generally about 8-12% (calculated by HF), and the concentration of produced fluorine acid is low. Along with the reduction of the fluorine content in the raw ore, the concentration of the fluoric acid in the mixed acid which is enriched by evaporation is correspondingly lower, so that the concentration of the fluoric acid produced by evaporation is reduced (the concentration of the fluoric acid is less than 10 percent (calculated by HF)), and the recycling of the downstream fluoric acid is directly influenced. CN222738518U discloses a fluorine-containing mixed acid rectification system for improving waste acid treatment effect, which comprises a sulfuric acid heat exchanger, a desulfurization acid making device, a sulfuric acid water cooler, a sulfuric acid storage tank, a first rectifying tower top tank and a first rectifying tower top cooler, wherein the top inlet of the sulfuric acid heat exchanger is connected with a sulfuric acid pipeline, the top outlet is communicated with the middle upper part of the first rectifying tower, the bottom inlet is connected with the desulfurization acid making device, and the bottom outlet is communicated with one side inlet of the sulfuric acid water cooler. The mixed acid output in the desulfurization and acid making device and the sulfuric acid output by the sulfuric acid pipeline can be subjected to heat exchange, the sulfuric acid after heat exchange is divided into two parts, one part is cooled by water to obtain sulfuric acid, the other part enters the first rectifying tower to be rectified, the top gas of the first rectifying tower is cooled and then pumped into the first rectifying tower by the first rectifying tower top pump to be rectified again, and the sulfuric acid in the mixed acid can be extracted with maximum efficiency. But this device cannot handle high concentrations of fluoric acid. CN113788460B discloses a method for separating and recovering fluorine-containing concentrated sulfuric acid, which comprises two-stage circulation of desalted water, HF separation, HF absorption, HF tail gas absorption, and the method separates HF in the fluorine-containing concentrated sulfuric acid, separates and recovers hydrofluoric acid products meeting production requirements and obtains dilute sulfuric acid products meeting purity requirements, thereby realizing comprehensive resource regeneration and utilization of fluorine-containing waste concentrated sulfuric acid. Although high-concentration hydrofluoric acid and 56-60% sulfuric acid can be recovered, KOH is required to absorb HF, K+ is introduced, KF wastewater is produced, in view of the actual condition that all wastewater needs to be treated and then recycled to production at present, the introduced K+ can influence the production operation of a main process, and the method is not applicable to the separation of fluorine-sulfur mixed acid after the tail gas of rare earth concentrate roasting is purified. The CN111620306B is a mixed acid separation and recovery treatment method, wherein the mixed acid comprises nitric acid, hydrofluoric acid, sulfuric acid and phosphoric acid, the method comprises the steps of mixing the mixed acid with calcium salt, carrying out solid-liquid separation after reaction to obtain calcium fluoride precipitate and supernatant, carrying out primary distillation and secondary distillation on the supernatant in sequence, separating out nitric acid during primary distillation, obtaining sulfuric acid and pyrophosphoric acid during secondary distillation, mixing the calcium fluoride precipitate with sulfuric acid, carrying out reaction to obtain hydrofluoric acid and calcium sulfate, mixing pyrophosphoric acid with an additive, carrying out reaction to obtai