RU2154605C1 - Powdered activated carbon production process - Google Patents

Abstract

FIELD: carbon materials. SUBSTANCE: invention relates to production of activated carbon useful in drinking water treatment and can be used in chemical- pharmaceutical and food industries. Carbon-containing material is ground at grinding apparatus filling factor 0.05-0.10 and ground carbon is granulated with binding agent to give granules with content of volatiles 26-38%. Wet granules are partially dried with heating rate 2-5 C/min to temperature 40-50 C and then carbonized at 650-800 C in medium composed of fuel combustion products, activated, and ground to powder form. EFFECT: increased adsorption capacity regarding crude water organics. 3 ex

Description

 The invention relates to a technology for producing activated carbon used for purification of drinking water, and can be used in the pharmaceutical, chemical and food industries.

A known method of producing activated carbon, which includes the activation of carbonized material in two stages: in the first - at a temperature of 800-950 ^o C with steam to 38-48% burns, in the second - with steam containing 1-6% oxygen (see ed. St. USSR N 827383, class C 01 B 31/08, publ. 26.03.79).

 The disadvantage of this method is the low yield and increased fire hazard of the process.

Closest to the invention in terms of technical nature and the number of coinciding features is a method for producing powdered activated carbon, which includes obtaining coal tar granules with a volatile content of 22-24%, carbonization at 400-600 ^o C in carbon dioxide, heating without access of gaseous reagents 800-850 ^o C up to 850-950 ^o C with water vapor at a weight ratio of carbonaceous material and water vapor the temperature rise rate of 1 50-100 ^o C / hr and activation: 5 - 10 followed by grinding to a size of the active granules enee 100 microns (see. US Pat. Russian Federation N 2023661, publ. 08.10.93).

 The disadvantage of the prototype is the low adsorption activity of the obtained powdered activated carbon (PAH) by the amount of organic impurities in the purified water.

 The aim of the invention is to increase the adsorption activity of the resulting activated carbon in the amount of organic compounds present in the purified water. According to existing standards, the quality of water by the amount of organic compounds or the effectiveness of activated carbon used for its purification is evaluated by permanganate oxidation, which indicates the number of milligrams of oxygen required for complete decomposition of organic matter (see GOST R 51232-98). In other words, the less permanganate oxidizability, the higher the efficiency of PAHs for purified water.

The goal is achieved by the proposed method, including grinding a carbon-containing material, forming granules using a binder, carbonizing them, activating and then grinding them to a powder form, and the content of volatiles in the molded granules should be 26-38 wt. %, the raw granules are dried before carbonization at a heating rate of 2-5 ^o C / min to a temperature of 40-50 ^o C, carbonization is carried out at a temperature of 650-800 ^o C in an inert medium, and grinding is carried out at a fill factor of the grinding apparatus of 0, 05-0.10.

The difference of the proposed method from the prototype is that the content of volatiles in the molded granules should be 26-38 wt.%, The raw granules are dried before carbonization at a heating rate of 2-5 ^o C / min to a temperature of 40-50 ^o C in an inert medium and grinding is carried out at a fill factor of the grinding apparatus equal to 0.05-0.10.

The authors of the patent and scientific literature do not know a method for producing PAHs in which the content of volatiles in the molded granules should be 26-38 wt.%, The raw granules are dried before carbonization at a heating rate of 2-5 ^o C / min to a temperature of 40- 50 ^o C, carbonization is carried out at a temperature of 650-800 ^o C in an inert medium, and grinding is carried out at a fill factor of the grinding apparatus equal to 0.05-0.10.

 The essence of the proposed method is as follows.

 For complete adsorption from water during purification of all organic compounds, it is necessary to ensure the development of all kinds of pores in PAH particles: fine micropores for adsorption of low molecular weight organic substances with a molecular weight of up to 100, large micropores (supermicropores) for adsorption of medium molecular weight substances with a molecular weight of up to 200, mesopores for the adsorption of high molecular weight substances with a molecular weight above 200.

 The formation of mesopores is ensured if the content of volatile substances in the initial raw granules is sufficiently high.

 At the same time, limiting grinding and subsequent molding with compaction of the structure in combination with slow drying of the granules subsequently allows the development of a significant volume of micropores. Carbonization should make it possible to fix the structure of the obtained crystallites and prevent micropores from overgrowing into mesopores. Therefore, carbonization should be carried out at significantly higher temperatures than required by the technology for producing known activated carbons.

 On the other hand, the efficiency of purification of drinking water, especially at the stage of its carbohydrate (introducing PAHs directly into the reagent chamber), depends on the uniformity of PAH particles, which can be obtained by setting a specific grinding regime, the most important parameter of which is the filling coefficient of the grinding apparatus.

 The implementation of all the advanced provisions allows to obtain PAHs using which the lowest permanganate oxidation rate is achieved when cleaning (treating) drinking water.

 The method is as follows.

The crushed carbon-containing material (coal, semi-coke or their mixture) is taken, mixed with a binder (coal and / or forest chemical resin) until a homogeneous paste is formed, while the content of volatile substances in the raw granules, which should be 26-38 wt.%, Is controlled. The paste is formed on a screw press through dies with a hole diameter of 1.0-3.5 mm. Raw granules are fed to the elevator, into which air heated to a temperature of 40-50 ^o C enters, and they are dried to the indicated temperature with a heating rate of 2-5 ^o C / min, after which the dried granules are sent to a carbonization furnace, where they are heat treated at a temperature of 650-800 ^o C in an inert gas (combustion product of natural gas, oil or solid fuel), followed by activation in a vertical shaft, a horizontal rotary kiln or other furnace structure at a temperature of 850-950 ^o C with superheated steam m at a rate of 5.10 kg to 1 kg coal discharged. The obtained active granules are cooled and sent without sieving to the grinding apparatus (ball mill, pendulum mill, KID crusher, etc.), maintaining a fill factor in the range of 0.05-0.10.

 The finished powdery product is unloaded into paper bags, drums or tanks, analyzed, packaged and sent to the consumer.

 The quality assessment of the obtained powdered coal for water purification is carried out by the standard method according to GOST R 51232-98, determining permanganate oxidation in purified water.

 For PAHs obtained by the proposed method, it is 2.0-2.5 mg O / L. Permanganate oxidation of purified water according to the prototype is 4.0-4.5 mg O / L (O - oxygen).

Example 1
Take 3.5 kg of SS brand coal (GOST 10355-75) and 3.5 kg of semi-coke of long-flame coal brand D (GOST 5442-74), crushed in a ball mill to a particle size of 20-90 microns, and mix them with 3, 0 kg of coal tar (TU 14-7-100-89 grade A) and 0.5 kg of water. The mixing process is carried out for 12-15 minutes The content of volatiles in raw granules is 26 wt.%. The paste is formed through dies with a hole diameter of 1.8 mm. The granules exiting the spinnerets are fed to an elevator into which air heated to a temperature of 40 ^° C is supplied, and granules are dried to a specified temperature with a heating rate of 2 ^° C / min, after which the dried granules are sent to a carbonization furnace, where they are heat treated at temperature of 650 ^o C in the environment of products of combustion of natural gas. The carbonized granules are cooled and fed into the vertical shaft furnace for activation, where they are activated with superheated steam at a rate of 5 kg of steam per 1 kg of coal discharged at a temperature of 850 ^o C by alternating the penetration of the granule layer in the direction perpendicular to its movement.

 The obtained active granules are cooled and sent without sieving to a ball mill, maintaining the fill factor of the mill equal to 0.05.

 The obtained powdered activated carbon with a particle size of 20-90 microns is analyzed by water purification. Permanganate oxidation of water purified by the obtained PAHs was 2.3 mg O / L.

Example 2
Analogously to example 1, except that they take 7.0 kg of crushed SS brand coal (GOST 10355-75) without the addition of semi-coke and mix with 30 kg of prepared wood chemical resin (GOST 22989-78 grade B), the content of volatile substances in granules after formation is 38 wt. %, the granules are dried with air heated to 50 ^o C with a heating rate of 5 ^o C / min, carbonization is carried out at a temperature of 800 ^o C, and the grinding of active granules is carried out at a ball mill filling factor of 0.10.

 Permanganate oxidation of water purified by the obtained PAHs was 2.5 mg O / L.

Example 3
Analogously to example 1, except that the content of volatile substances in the granules after molding is 32 wt.%, The granules are dried with air heated to 45 ^o C with a heating rate of 3.5 ^o C / min, carbonization is carried out at a temperature of 720 ^o C, and grinding of active granules is carried out at a ball mill fill factor of 0.07.

 Permanganate oxidation of water purified by the obtained PAHs was 2.0 mg O / L.

 From the foregoing, it follows that each of the signs of the claimed combination to a greater or lesser extent affects the achievement of the goal, namely, to reduce the permanganate oxidation of water purified from the resulting powdered activated carbon from organic substances.

Claims (1)

A method of producing powdered activated carbon, including grinding a carbon-containing material, forming granules using a binder, carbonizing them, activating and then grinding them to a powder form, characterized in that the volatile content in the molded granules should be 26 - 38 wt.%, Raw granules before dried by carbonization at a heating rate of 2 - 5 ^o C / min to 40 - 50 ^o C, carbonization is carried out at 650 - 800 ^o C in the environment of the combustion products of natural gas, fuel oil or solid fuel, and crushed The lead is carried out at a fill factor of the grinding apparatus equal to 0.05 - 0.10.