CN102107872A - A process for preparing activated carbon by adding fruit shells to chemical sludge - Google Patents

Abstract

The invention relates to a process for preparing activated carbon by adding shells into chemical sludge. Excess sludge generated by sewage treatment in the chemical industry is taken as a raw material, and after the sludge is dried, shells are added, and an activating agent is added after grinding. Drying, carbonizing and activating under the protection of inert gas. And finally, cooling, washing and drying to obtain the sludge-based activated carbon. The invention takes a large amount of excess sludge generated by sewage treatment in the chemical industry as raw materials for preparation, reduces the discharge amount of the excess sludge in the chemical industry, reduces the preparation cost of the activated carbon adsorbent, and has obvious environmental benefit and economic benefit. The concentration of heavy metals in the prepared activated carbon is lower than the highest allowable concentration of leachate specified in the national standard GB 5085.3-2007 (hazardous waste identification standard leaching toxicity identification); meanwhile, under the condition of high-temperature pyrolysis, organic matters in the sludge can be completely mineralized. The active carbon prepared by the method can be used in the fields of wastewater treatment, waste gas absorption and the like, and has wide market prospect.

Description

A process for preparing activated carbon by adding fruit shells to chemical sludge

technical field

The invention relates to resource disposal of industrial solid waste, in particular to a process for preparing activated carbon by adding fruit shells to chemical sludge.

Background technique

The sludge in the chemical industry is not only bulky, but also contains high organic poisons, fine particles, flocculent colloidal structure, and high hydrophilicity. There are more than 1,000 large and small chemical parks in my country, with more than 100,000 large and small chemical enterprises. These chemical companies produce tens of thousands of tons of excess sludge every day, and the water content of the sludge is as high as 95%. After the sludge is filtered by belt filter, the water content drops to 70-85%, because it contains various organic poisons and heavy metals. . According to the latest "National Hazardous Waste List" promulgated by our country, the residual sludge generated in the process of wastewater treatment in chemical, pharmaceutical and pesticide industries is hazardous solid waste, which must be sent to a qualified hazardous waste disposal center for centralized treatment. The disposal cost is about 2000 yuan/ton.

The cost of chemical sludge incineration in my country is high, and many chemical companies turn to landfill or compost to dispose of the remaining sludge. Because the sludge contains a large amount of organic toxic substances, landfill or compost is likely to cause serious secondary pollution and endanger the ecological environment. Composting takes up a lot of farmland. Research and development of economical and efficient treatment technologies for toxic sludge. Therefore, how to dispose of urban sludge more effectively and turn urban sludge into treasure is an urgent problem in the field of environmental protection.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art, and provide a process for preparing activated carbon by adding fruit shells to chemical sludge, and carry out carbonization and activation treatment on sludge in a simple manner, and the obtained carbonization activation material can be used instead of activated carbon. Realize the resource utilization of sludge.

The technical scheme of the present invention is: a process for preparing activated carbon by adding fruit shells to chemical sludge, and its specific steps are as follows:

(1), after drying the chemical sludge after belt filter press dehydration, dry sludge is obtained;

(2), adding dried fruit shells to the dried sludge to obtain a mixed material, and then grinding;

(3) Add activation solution, soak and activate at a temperature of 50-100°C for 2-10 hours, stir while activating; then dry;

(4) Using inert gas as protective gas, pyrolyze at 600-900°C for 0.5-5 hours;

(5), cooling, washing, and drying to obtain sludge activated carbon.

Preferably, the drying temperature in steps (1) and (3) is 105-120° C., and the drying time is 4-24 hours. The drying process in the step (5) selects conventional method drying.

Preferably, the dried fruit shell is at least one of coconut shell, apricot core or walnut shell; the amount of dried fruit shell added per kilogram of dried sludge is 5 to 30 g; the average particle size of the mixed material after grinding is 0.15 ~1mm.

Preferably, the activation solution is at least one of zinc chloride, potassium hydroxide or potassium sulfide aqueous solution; wherein the concentration of the activation solution is 1 to 5 mol/L; the amount of activation solution added per kilogram of dried sludge 0.5-2L.

Preferably, the stirring speed after adding the activation solution is 100-200 r/min.

Preferably, the inert gas is nitrogen, helium or argon; the purge rate of the inert gas is 100-200 mL/min.

Preferably, the heating rate during the pyrolysis process is 10-20° C./min.

Preferably, the washing process is as follows: washing with 0.8-1.5 mol/L hydrochloric acid solution and drying; then washing with water and drying to obtain sludge activated carbon.

The invention prepares activated carbon by using chemical industry dewatered sludge as a raw material, breaking through the traditional process of preparing activated carbon from coal and wood and using residual sludge of domestic sewage to prepare activated carbon.

Beneficial effect:

Compared with traditional sludge disposal and activated carbon preparation methods, it has the following advantages:

1. The preparation of activated carbon from chemical dewatered sludge breaks through the traditional process of preparing activated carbon from coal, wood and domestic sewage sludge, and also opens up a new way of solid waste treatment.

2. Prepare activated carbon from chemical dewatered sludge, find a way out for sludge treatment and disposal, and at the same time find cheap, available and widely sourced raw materials for activated carbon production, which can alleviate the contradiction of wood and energy shortages in my country.

3. The preparation of activated carbon from sludge has achieved the purpose of "turning waste into treasure" and "treating waste with waste", and has good environmental and social benefits. Under high-temperature pyrolysis conditions, the carbon-containing organic matter in the sludge decomposes under the action of heat, non-carbon elements escape in the form of volatile matter, the organic matter in the sludge can be completely mineralized, and the heavy metal leaching concentration of activated carbon is far away. It is lower than the maximum allowable concentration of the leach solution stipulated in the national standard GB5085.3-2007 (Leach Toxicity Identification of Hazardous Waste Identification Standard).

Detailed ways

Example 1:

Take the residual sludge of a petrochemical plant with a mass moisture content of 75%, dry it at 120°C for 6 hours, weigh 1kg of dried sludge, add 5g of coconut shell in turn, grind until the average particle size is 0.71mm, and then add 0.5L to a concentration of 3mol /L potassium hydroxide activation solution; soak and activate at 90°C for 4h, stir at 150r/min while activating, and dry (dry at 120°C for 4h). Under the protection of 600°C (heating rate of 15°C/min) and nitrogen purge rate of 150mL/min, pyrolysis was carried out for 3h. Cool, wash with 1mol/L hydrochloric acid, and dry; then wash with water, and dry to obtain activated carbon. The measured specific surface area is: 441m ² /g, and its heavy metal leaching concentration is shown in Table 1.

Example 2:

Take the residual sludge from a sewage treatment plant of a pesticide factory with a mass moisture content of 80%, dry it at 110°C for 8 hours, weigh 1kg of dried sludge, add 15g of apricot kernels in turn, grind until the average particle size is 0.50mm, and then add 1L concentration Potassium hydroxide and zinc chloride solutions of 3 mol/L; soak and activate at 85°C for 6h, stir at 100r/min while activating, and dry (dry at 110°C for 8h). Under the protection of 700°C (heating rate of 10°C/min) and helium purge rate of 100mL/min, pyrolysis was carried out for 2.5h. Cool, wash with 0.8mol/L hydrochloric acid, and dry; then wash with water, and dry to obtain activated carbon. The measured specific surface area is: 465m ² /g, and its heavy metal leaching concentration is shown in Table 1.

Example 3:

Take the residual sludge of a sewage treatment plant of a pharmaceutical and chemical factory with a mass moisture content of 85%, dry it at 105°C for 24 hours, weigh 1kg of dried sludge, add 30g of peach pits in turn, grind until the average particle size is 0.15mm, and then add 2L Potassium sulfide solution with a concentration of 1mol/L; soak and activate at 75°C for 8h, and dry at 200r/min while activating (dry at 105°C for 24h). Under the protection of 800°C (heating rate of 20°C/min) and argon purge rate of 180mL/min, pyrolysis was carried out for 5h. Cool, wash with 1.5mol/L hydrochloric acid, and dry; then wash with water, and dry to obtain activated carbon. The measured specific surface area is: 510m ² /g, and its heavy metal leaching concentration is shown in Table 1.

Table 1 Analysis of heavy metal content in leaching solution in activated carbon leaching toxicity identification test

Claims (8)

1. a chemical engineering sludge adds the technology that shell prepares gac, and its concrete steps are as follows:

(1), with after the chemical engineering sludge drying behind the belt filter-press dehydration, obtain dewatered sludge;

(2), adding the dry fruit shell in dewatered sludge gets mixture, grinding again;

(3), add activation solution, dipping activation under 50～100 ℃ temperature, soak time is 2～10h, the stirring while activate; Dry then;

(4), with rare gas element as the protection gas, at 600～900 ℃ of pyrolysis 0.5～5h;

(5), cooling, washing, drying, make active sludge carbon.

2. technology according to claim 1 is characterized in that the drying temperature in step (1) and (3) is 105～120 ℃, and be 4～24h time of drying.

3. technology according to claim 1 is characterized in that described dry fruit shell is at least a kind of in coconut husk, almond or the nut-shell; Wherein in the per kilogram dewatered sludge, the addition of dry fruit shell is: 5～30g; Median size after mixture grinds is 0.15～1mm.

4. technology according to claim 1 is characterized in that described activation solution is at least a kind of in zinc chloride, potassium hydroxide or the potassium sulfide aqueous solution; Wherein the concentration of activation solution is 1～5mol/L; In the per kilogram dewatered sludge, the add-on of activation solution is 0.5～2L.

5. technology according to claim 1, the stir speed (S.S.) that it is characterized in that adding after the activation solution is 100～200r/min.

6. technology according to claim 1 is characterized in that described rare gas element is nitrogen, helium or argon gas; The purge rates of rare gas element is 100～200mL/min.

7. technology according to claim 1 is characterized in that the temperature rise rate in the described pyrolytic process is 10～20 ℃/min.

8. technology according to claim 1 is characterized in that described washing process is for washing drying earlier with 0.8～1.5mol/L hydrochloric acid soln; Through washing, drying makes active sludge carbon again.