A kind of activated carbon regeneration process

Abstract

The present invention discloses an activated carbon regeneration process, comprising the following steps: step 1, pickling, using hydrochloric acid and nitric acid to prepare a pickling solution, putting the activated carbon to be regenerated into the pickling solution, and stirring the activated carbon; step 2, accelerating the pickling, when stirring the pickling, accelerating the pickling efficiency by ultrasonic waves, so that the pickling solution completely enters the activated carbon. The present invention has the advantage of good regeneration effect, solves the problem that in the process of regenerating activated carbon in the existing activated carbon regeneration process, it is not convenient to make the pickling solution completely enter the pore size of the activated carbon, which reduces the pickling effect and affects the subsequent dissociation of the activated carbon. When using nitric acid for pickling, it is not convenient to remove the nitrate produced by the nitric acid reaction, which is easy to cause environmental pollution.

Description

Technical Field

[0001] The invention relates to the field of activated carbon, in particular to an activated carbon regeneration process. Background Art

[0002] The method of gold beneficiation is mature, and cyanide leaching is used to dissolve gold and activated carbon is used for absorption. In other studies, most of them use cyanide-free agents for improvement, but due to economic costs and equipment costs, they cannot be applied on a large scale. However, there is still room for improvement in the cyanide leaching process of gold beneficiation. The key problem lies in the activated carbon adsorption process. Most of the activated carbon commonly used today is made from coconut shells, sugarcane and other materials. Its surface is loose and porous and has many adsorption points. In the process of precious liquid adsorption, not only will the gold complex be adsorbed on the site, but also the gangue minerals, engine oil, lubricating oil and other organic matter in the production process will be adsorbed. The activated carbon after adsorption cannot completely release the gold during the cleavage process, and it will remain inside the activated carbon, thereby reducing the gold recovery rate.

[0003] In the secondary activation process of activated carbon, due to the indiscriminate adsorption performance of activated carbon, many Ca2+, Fe3+ and other ions will be adsorbed on the activated carbon. These ions are mainly produced in gangue minerals and mineral processing equipment. Since NaOH, lime and other substances are used for pH adjustment in mineral processing, the ions in the ore pulp are very complex. Ca2+ ions will react with CO2 to form calcium carbonate. These impurities will be adsorbed on the activated carbon and occupy the adsorption points in the activated carbon. The general treatment method is to use acid washing to remove these substances, but due to the internal structure of the activated carbon, the solution cannot diffuse quickly inside. At the same time, due to the hydrophobicity of the activated carbon itself, cavities may even be formed at some adsorption points, thereby affecting the adsorption efficiency of the activated carbon.

[0004] In the process of regenerating activated carbon, the existing activated carbon regeneration process is not convenient for the pickling solution to completely enter the pore size of the activated carbon, which reduces the effect of pickling and affects the subsequent dissociation of the activated carbon. When using nitric acid for pickling, it is not convenient to remove the nitrate produced by the nitric acid reaction, which easily causes environmental pollution. Summary of the invention

[0005] The purpose of the present invention is to provide an activated carbon regeneration process with the advantage of good regeneration effect, which solves the problem that in the process of regenerating activated carbon in the existing activated carbon regeneration process, it is not convenient for the pickling liquid to completely enter the pore size of the activated carbon, thereby reducing the pickling effect and affecting the subsequent dissociation of the activated carbon. When nitric acid is used for pickling, it is not convenient to remove the nitrate produced by the nitric acid reaction, which easily causes environmental pollution.

[0006] To achieve the above object, the present invention provides the following technical solution: an activated carbon regeneration process, comprising the following steps:

[0007] Step 1, pickling, using hydrochloric acid and nitric acid to prepare a pickling solution, putting the activated carbon to be regenerated into the pickling solution, and stirring the activated carbon;

[0008] Step 2, accelerating pickling, during stirring pickling, using ultrasound to accelerate the pickling efficiency so that the pickling solution completely enters the activated carbon;

[0009] Step 3: removing hydrocyanic acid by using a chlorine dioxide solution to eliminate hydrocyanic acid, oxidizing cyanide into cyanate through the oxidation action of the chlorine dioxide solution, and finally further oxidizing into carbon dioxide and nitrogen;

[0010] Step 4, denitration: after the acid washing is completed, microwaves and a denitration catalyst are used to denitrate the nitration in the waste activated carbon;

[0011] Step 5: Dissociation: Soak the activated carbon in sodium chloride solution and sodium hydroxide solution. After soaking, rinse the activated carbon with ionized water to wash away the gold in the activated carbon.

[0012] Step 6: washing, washing the dissociated activated carbon for a second time to wash away impurities on the surface of the activated carbon;

[0013] Step 7: Drying: drying and dehydrating the cleaned activated carbon to allow the activated carbon to be regenerated subsequently;

[0014] Step 8: high temperature carbonization, using high temperature to carbonize the volatile substances adsorbed on the activated carbon and the high boiling point organic matter remaining in the pores of the activated carbon. The high boiling point organic adsorbate is thermally decomposed, and the part converted into small molecular substances is directly desorbed, and the remaining part is converted into a fixed carbon form through a condensation reaction and remains in the pores;

[0015] Step 9, high temperature activation, the activated carbon micropores are cleaned by adding water vapor and the oxidation reaction in the roasting stage to generate CO2 gas, and the organic carbon residues blocked in the activated carbon pores are vaporized, thereby restoring its adsorption performance.

[0016] As a preferred activated carbon regeneration process of the present invention, the stirring time in step 1 is 30-60 minutes.

[0017] As a preferred activated carbon regeneration process of the present invention, the ultrasonic frequency in step 2 is 20-30 Hz.

[0018] As a preferred activated carbon regeneration process of the present invention, the denitration temperature in step 4 is 100-300° C., and the denitration time is 20-40 min.

[0019] As a preferred activated carbon regeneration process of the present invention, the concentration of the sodium chloride solution in step 5 is 4%-5%, the concentration of the sodium hydroxide solution is 2%, and the soaking time is 1-2h.

[0020] As a preferred activated carbon regeneration process of the present invention, the ion water washing time in step 5 is 6-8h and the washing temperature is 80-120°C.

[0021] As a preferred activated carbon regeneration process of the present invention, the drying temperature in step 7 is 100-150°C.

[0022] As a preferred activated carbon regeneration process of the present invention, the high-temperature carbonization temperature in step 8 is 350-800°C.

[0023] As a preferred activated carbon regeneration process of the present invention, the high temperature activation temperature in step 9 is 800-1000°C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention can remove impurities adsorbed inside the pores of activated carbon by pickling the activated carbon, so as to avoid affecting the subsequent dissociation and gold removal of the activated carbon. In the process of pickling, a solution prepared by hydrochloric acid and nitric acid is used to increase the effect of pickling. Stirring during the pickling process can make the acid solution and the activated carbon contact evenly.

[0026] 2. The present invention uses ultrasound to accelerate pickling during the pickling process, so that the pickling solution can evenly enter the pores of the activated carbon, so that the pickling solution can completely remove organic matter and increase the subsequent dissociation effect of the activated carbon.

[0027] 3. The present invention ensures safe and reliable operation of the overall reaction by removing hydrocyanic acid during the pickling process. During the pickling process, due to the presence of cyanide ions in the waste activated carbon, hydrocyanic acid will precipitate in the presence of weak acid. Chlorine dioxide solution is used to eliminate hydrocyanic acid, and cyanide is oxidized to cyanate through the oxidation action of chlorine dioxide solution, and finally further oxidized to carbon dioxide and nitrogen.

[0028] 4. The present invention heats the activated carbon and the denitration catalyst by microwaves, so that the denitration catalyst removes the nitrate in the activated carbon, thereby avoiding the emission of nitrate to pollute the environment. The activated carbon is dissociated by immersing it in a sodium chloride solution and a sodium hydroxide solution. After the dissociation is completed, the activated carbon is rinsed with ionized water to rinse away the gold in the activated carbon.

[0029] 5. The present invention can remove impurities on the surface of the activated carbon by performing secondary flushing on the activated carbon, which is convenient for subsequent regeneration of the activated carbon. After regeneration, the activated carbon is dried to facilitate subsequent transportation and high-temperature carbonization of the activated carbon.

[0030] 6. The present invention can carbonize the organic matter on the activated carbon by high-temperature carbonization. The organic matter is decomposed and separated from the surface of the activated carbon by high temperature. After the high-temperature carbonization, the activated carbon is activated at high temperature. The high-temperature activation vaporizes the organic matter residue in the pores of the activated carbon, so that the activated carbon is regenerated with adsorption performance. DETAILED DESCRIPTION

[0031] Example:

[0032] An activated carbon regeneration process comprises the following steps:

[0033] Step 1, pickling, using hydrochloric acid and nitric acid to prepare a pickling solution, putting the activated carbon to be regenerated into the pickling solution, and stirring the activated carbon for 45 minutes. By pickling the activated carbon, the impurities adsorbed inside the pores of the activated carbon can be removed to avoid affecting the subsequent dissociation and gold removal of the activated carbon. In the process of pickling, using a solution prepared with hydrochloric acid and nitric acid can increase the effect of pickling. Stirring during the pickling process can ensure uniform contact between the acid solution and the activated carbon.

[0034] Step 2, accelerate pickling. During the stirring pickling, the pickling efficiency is accelerated by ultrasound, so that the pickling solution can completely enter the activated carbon. The frequency of the ultrasound is 25HZ. By using ultrasound to accelerate the pickling during the pickling process, the pickling solution can evenly enter the pores of the activated carbon, so that the pickling solution can completely remove the organic matter and increase the subsequent dissociation effect of the activated carbon.

[0035] Step 3, removing hydrocyanic acid, using chlorine dioxide solution to eliminate hydrocyanic acid, oxidizing cyanide to cyanate through the oxidation of chlorine dioxide solution, and finally further oxidizing to carbon dioxide and nitrogen. By removing hydrocyanic acid during the pickling process, the safe and reliable operation of the overall reaction is ensured. During the pickling process, due to the presence of cyanide ions in the waste activated carbon, hydrocyanic acid will precipitate in the case of weak acid. Using chlorine dioxide solution to eliminate hydrocyanic acid, oxidizing cyanide to cyanate through the oxidation of chlorine dioxide solution, and finally further oxidizing to carbon dioxide and nitrogen.

[0036] Step 4, denitration. After the acid wash is completed, microwaves and a denitration catalyst are used to denitrate the nitrate in the waste activated carbon. The denitration temperature is 200°C and the denitration time is 30 minutes. The activated carbon and the denitration catalyst are heated by microwaves so that the denitration catalyst removes the nitrate in the activated carbon to avoid the emission of nitrates to pollute the environment.

[0037] Step 5, dissociation, soaking the activated carbon in sodium chloride solution and sodium hydroxide solution. After the soaking is completed, the activated carbon is rinsed with ionized water to rinse away the gold in the activated carbon. The concentration of the sodium chloride solution is 5%, the concentration of the sodium hydroxide solution is 2%, the soaking time is 1.5 hours, the ionized water rinsing time is 7 hours, and the rinsing temperature is 100°C. The activated carbon is dissociated by soaking it in sodium chloride solution and sodium hydroxide solution. After the dissociation is completed, the activated carbon is rinsed with ionized water to rinse away the gold in the activated carbon.

[0038] Step 6, cleaning, the dissociated activated carbon is rinsed twice to wash away impurities on the surface of the activated carbon. By performing the secondary rinse on the activated carbon, impurities on the surface of the activated carbon can be removed, which facilitates the subsequent regeneration of the activated carbon.

[0039] Step 7, drying, drying and dehydrating the cleaned activated carbon to enable subsequent regeneration of the activated carbon. The drying temperature is 125°C. After regeneration, the activated carbon is dried to facilitate subsequent transportation and high-temperature carbonization of the activated carbon.

[0040] Step 8, high-temperature carbonization, use high temperature to carbonize the volatile substances adsorbed on the activated carbon and the high-boiling point organic matter remaining in the pores of the activated carbon. The high-boiling point organic adsorbent is thermally decomposed, and the part converted into small molecules is directly desorbed, and the remaining part becomes a fixed carbon form through a condensation reaction and remains in the pores. The high-temperature carbonization temperature is 350-800°C. By performing high-temperature carbonization on the activated carbon, the organic matter on the activated carbon can be carbonized, and the organic matter is decomposed and separated from the surface of the activated carbon by high temperature.

[0041] Step 9, high temperature activation, the activated carbon micropores are cleaned by adding water vapor and the oxidation reaction in the roasting stage to generate CO2 gas, and the organic carbon residues blocked in the activated carbon pores are vaporized, so as to restore its adsorption performance. The high temperature activation temperature is 800-1000°C. After high temperature carbonization, the activated carbon is high temperature activated. The high temperature activation vaporizes the organic residues in the activated carbon pores, so that the activated carbon is regenerated with adsorption performance.

[0042] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An activated carbon regeneration process, characterized in that: The following steps are involved: Step 1, pickling, using hydrochloric acid and nitric acid to prepare a pickling solution, putting the activated carbon to be regenerated into the pickling solution, and stirring the activated carbon; Step 2, accelerating pickling, during stirring pickling, using ultrasound to accelerate the pickling efficiency so that the pickling solution completely enters the activated carbon; Step 3: removing hydrocyanic acid by using a chlorine dioxide solution to eliminate hydrocyanic acid, oxidizing cyanide into cyanate through the oxidation action of the chlorine dioxide solution, and finally further oxidizing into carbon dioxide and nitrogen; Step 4, denitration: after the acid washing is completed, microwaves and a denitration catalyst are used to denitrate the nitration in the waste activated carbon; Step 5: Dissociation: Soak the activated carbon in sodium chloride solution and sodium hydroxide solution. After soaking, rinse the activated carbon with ionized water to wash away the gold in the activated carbon. Step 6: washing, washing the dissociated activated carbon for a second time to wash away impurities on the surface of the activated carbon; Step 7: Drying: drying and dehydrating the cleaned activated carbon to allow the activated carbon to be regenerated subsequently; Step 8: high temperature carbonization, using high temperature to carbonize the volatile substances adsorbed on the activated carbon and the high boiling point organic matter remaining in the pores of the activated carbon. The high boiling point organic adsorbate is thermally decomposed, and the part converted into small molecular substances is directly desorbed, and the remaining part is converted into a fixed carbon form through a condensation reaction and remains in the pores; Step 9, high temperature activation, the activated carbon micropores are cleaned by adding water vapor and the oxidation reaction in the roasting stage to generate CO2 gas, and the organic carbon residues blocked in the activated carbon pores are vaporized, thereby restoring its adsorption performance.

2. An activated carbon regeneration process according to claim 1, characterized in that: The stirring time in step 1 is 30-60 min.

3. An activated carbon regeneration process according to claim 1, characterized in that: The ultrasonic frequency in step 2 is 20-30 Hz.

4. An activated carbon regeneration process according to claim 1, characterized in that: The denitration temperature in step 4 is 100-300° C., and the denitration time is 20-40 minutes.

5. An activated carbon regeneration process according to claim 1, characterized in that: The concentration of the sodium chloride solution in step 5 is 4%-5%, the concentration of the sodium hydroxide solution is 2%, and the soaking time is 1-2h.

6. An activated carbon regeneration process according to claim 1, characterized in that: The ion water washing time in step 5 is 6-8 hours, and the washing temperature is 80-120°C.

7. An activated carbon regeneration process according to claim 1, characterized in that: The drying temperature in step 7 is 100-150°C.

8. An activated carbon regeneration process according to claim 1, characterized in that: The high temperature carbonization temperature in step 8 is 350-800°C.

9. An activated carbon regeneration process according to claim 1, characterized in that: The high temperature activation temperature in step 9 is 800-1000°C.