A method for acid-base neutralization and filtration of waste acid from explosives manufacturing processes

Abstract

This invention discloses an acid-base neutralization and filtration method for treating waste acid from explosives processes, comprising the following steps: 1) Adding water and a first alkaline reagent to the waste acid from the explosives after acidification reaction, simultaneously cooling, stirring, and ultrasonicating, followed by washing, and filtering to recover solid particles, resulting in a first treated solution with the acidity reduced to pH 0.5-1; 2) Heating the first treated solution and adding a second alkaline reagent, simultaneously cooling, stirring, and ultrasonicating, followed by washing, and filtering using a ceramic filter plate to recover solid particles, resulting in a neutralized treated solution. This invention can solve the problems of high impurity content and easy clogging of filters during the initial treatment of waste acid.

Description

Technical Field

[0001] This invention belongs to the field of explosives technology, specifically relating to an acid-base neutralization and filtration method for treating waste acid from explosives processes. Background Technology

[0002] Explosives factories discharge large amounts of acidic wastewater during acid production, which contains various highly toxic substances. Therefore, the waste acid must be treated to meet emission standards before it can be discharged. However, the waste acid contains various organic compounds, which cause problems such as easy clogging of the filter in the early and middle stages of the washing and precipitation process, and difficulty in the precipitation of small molecules in the later stages. As a result, impurities are difficult to remove completely in the initial waste acid treatment process, and multiple post-treatment processes are required before it can be discharged. Therefore, the method needs to be optimized in the initial waste acid treatment process to ensure a significant reduction in impurities in the waste acid during the initial treatment. Summary of the Invention

[0003] To address the issues of high impurity levels and easy clogging of filters during the initial treatment of waste acid, this invention provides an acid-base neutralization filtration method for treating waste acid from explosives processes.

[0004] The acid-base neutralization and filtration method for treating waste acid from explosives processes according to the present invention includes the following steps: 1) Add water and a first alkaline reagent to the explosive waste acid after acidification reaction, while cooling and stirring, ultrasonic treatment, washing, filtering and recovering solid particles to obtain a first treatment solution with acidity reduced to pH 0.5-1. 2) After heating the first treatment solution, add the second alkaline reagent, and while cooling, stir and sonicate, wash, and filter and recover solid particles using a ceramic filter plate to obtain a neutralized treatment solution.

[0005] In step 1), the volume ratio of waste acid to water is 1:5-20, and the molar ratio of the acid anion of waste acid to the hydroxide ion of the first alkaline reagent is 10:2-7; the waste acid is one or more of nitric acid, nitric acid-sulfur mixture, sulfuric acid, acetic acid and hydrochloric acid; the first alkaline reagent is one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide and quicklime, and quicklime will turn into calcium hydroxide when it comes into contact with water.

[0006] In step 1), the explosive is any one of hexanitrohexaazaisowulzane (CL-20 or HNIW), triaminotrichlorobenzene (TCTNB), octogen (HMX), RDX, and trinitrotoluene (TNT).

[0007] In step 1), the initial temperature for cooling is 60℃-70℃, the temperature is reduced to 0℃-20℃, and the temperature gradient for cooling is 0.3-10℃ / min.

[0008] In step 2), the molar ratio of acid radicals in the first treatment solution to hydroxide radicals in the second alkaline reagent is 10:5-10. The second alkaline reagent is one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide, and quicklime. The first alkaline reagent and the second alkaline reagent may be the same or different.

[0009] In step 2), the temperature is increased to 70℃-85℃ and the temperature is decreased to 20℃, with a temperature gradient of 0.3-10℃ / min.

[0010] In step 2), the pore size of the ceramic filter plate is 0.5-80 micrometers.

[0011] In steps 1) and 2), the ultrasonic vibration frequency is 50-200 kHz, the vibration frequency gradient is 0-30 kHz / min, and the waste acid washing time is 5-30 min.

[0012] Beneficial effects: This invention neutralizes the waste acid after reaction by adding an alkaline reagent, followed by stirring and ultrasonic treatment. During the filtration process, a ceramic filter plate layer is added. By utilizing the micropores that generate capillary effect, the capillary force in the micropores is greater than the force applied by the vacuum, thus filtering the waste liquid. The filtration method of this invention can improve the problem of easy clogging in the initial waste acid filtration, effectively precipitate and recover fine particles in the waste acid, reduce the impurity content of the waste liquid, and improve the waste acid treatment efficiency. Detailed Implementation

[0013] The present invention will now be described in further detail through embodiments, but the present invention is not limited to the embodiments. Example

[0014] 1 L of TNT nitrate-sulfur mixed acid waste acid with a combined nitrate and sulfate concentration of 5 mol / L (as determined by chromatography) and 5 L of deionized water were added sequentially to a beaker. 2.5 mol of potassium hydroxide was added, and the mixture was stirred while cooling from 60 °C to 0 °C at a temperature gradient of 5 °C / min. The mixture was then subjected to ultrasonic treatment, with the ultrasonic frequency increasing from 50 kHz to 60 kHz at a gradient of 2 kHz / min. The washing time was 10 minutes. The solid particles were recovered by filtration using ordinary filter paper, resulting in a first-treatment solution with the acidity reduced to pH 0.5-1.

[0015] The concentrations of nitrate and sulfate in the first treatment solution were determined to be 2.5 mol / L using chromatography. 1 L of the solution was taken out and heated to 70°C. 2.5 mol of potassium hydroxide was added, and the solution was cooled from 70°C to 20°C while stirring, with a temperature gradient of 10°C / min. The solution was then subjected to ultrasonic treatment, with the ultrasonic frequency increasing from 50 kHz to 60 kHz at a gradient of 2 kHz / min. The washing time was 10 minutes. The waste acid was neutralized, and the solid particles were recovered by filtration using a ceramic filter plate with a pore size of 40 micrometers from Aivens (Jiaozuo) New Materials Co., Ltd. The COD content of the neutralized wastewater was 800 mg / mL. Example

[0016] 1 L of CL-20 nitric acid waste acid with a nitrate concentration of 5 mol / L determined by chromatography and 5 L of deionized water were added sequentially to a beaker. 2.5 mol of potassium hydroxide was added, and the mixture was stirred while cooling from 70 °C to 20 °C at a temperature gradient of 5 °C / min. The mixture was then ultrasonicated at 80 kHz for 10 minutes. The solid particles were recovered by filtration using ordinary filter paper, resulting in a first-treatment solution with the acidity reduced to pH 0.5-1.

[0017] The nitrate concentration in the first treatment solution was determined to be 5 mol / L using chromatography. 1 L of the solution was taken out and heated to 70°C. 2.5 mol of potassium hydroxide was added, and the solution was cooled from 70°C to 20°C while stirring. The temperature gradient was 10°C / min, and the ultrasonication was maintained at 80 kHz. The washing time was 10 minutes to neutralize the waste acid. Solid particles were recovered by filtering with a ceramic filter plate with a pore size of 40 micrometers from Aivens (Jiaozuo) New Materials Co., Ltd. The COD content of the neutralized wastewater was 1000 mg / mL.

[0018] Comparative Example 1 1 L of TNT nitrate-sulfur mixed acid waste acid with a total nitrate and sulfate concentration of 5 mol / L as determined by chromatography and 5 L of deionized water were added to a beaker in sequence. 2.5 mol of potassium hydroxide was added to each beaker in two separate additions. The mixture was stirred at 25 °C and washed for 10 minutes. The washing was repeated twice. The COD content of the wastewater was 2000 mg / mL.

[0019] Comparative Example 2 1 L of CL-20 nitric acid waste acid with a nitrate concentration of 5 mol / L determined by chromatography and 5 L of deionized water were added to a beaker in sequence. 2.5 mol of potassium hydroxide was added to each beaker in two separate additions. The mixture was stirred at 25 °C and washed for 10 minutes. The washing was repeated twice. The COD content of the wastewater was 2800 mg / mL.

[0020] Unless otherwise specified, all technologies mentioned above refer to existing technologies.

[0021] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.

Claims

1. A method for acid-base neutralization and filtration of waste acid from explosives manufacturing processes, characterized in that, Includes the following steps: 1) Add water and a first alkaline reagent to the explosive waste acid after acidification reaction, while cooling and stirring, ultrasonic treatment, washing, filtering and recovering solid particles to obtain a first treatment solution with acidity reduced to pH 0.5-1. 2) After heating the first treatment solution, add the second alkaline reagent, and while cooling, stir and sonicate, wash, and filter and recover solid particles using a ceramic filter plate to obtain a neutralized treatment solution. In step 1), the initial temperature for cooling is 60℃-70℃, the temperature is reduced to 0℃-20℃, and the temperature gradient for cooling is 0.3-10℃ / min; In step 2), the temperature is increased to 70℃-85℃ and the temperature is decreased to 20℃, with a temperature gradient of 0.3-10℃ / min.

2. The acid-base neutralization and filtration method for treating waste acid from explosives processes according to claim 1, characterized in that, In step 1), the volume ratio of waste acid to water is 1:5-20, and the molar ratio of the acid radical of waste acid to the hydroxide radical of the first alkaline reagent is 10:2-7; the waste acid is one or more of nitric acid, nitric acid-sulfur mixture, sulfuric acid, acetic acid and hydrochloric acid; the first alkaline reagent is one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide and quicklime.

3. The acid-base neutralization and filtration method for treating waste acid from explosives processes according to claim 1, characterized in that, In step 1), the explosive is any one of hexanitrohexaazaisowulzane, triaminotrichlorobenzene, octogen, RDX, and trinitrotoluene.

4. The acid-base neutralization and filtration method for treating waste acid from explosives processes according to claim 1, characterized in that, In step 2), the molar ratio of acid radicals in the first treatment solution to hydroxide radicals in the second alkaline reagent is 10:5-10, and the second alkaline reagent is one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide, and quicklime.

5. The acid-base neutralization and filtration method for treating waste acid from explosives processes according to claim 1, characterized in that, In step 2), the pore size of the ceramic filter plate is 0.5-80 micrometers.

6. The acid-base neutralization and filtration method for treating waste acid from explosives processes according to claim 1, characterized in that, In steps 1) and 2), the ultrasonic vibration frequency is 50-200 kHz, the vibration frequency gradient is 0-30 kHz / min, and the waste acid washing time is 5-30 min.