RU2154604C1 - Method of preparing activated carbon for detoxification of feeds in poultry farming - Google Patents

Abstract

FIELD: carbon materials. SUBSTANCE: activated carbon is prepared from carbon-containing raw material and binding agent in a process including compaction of divided carbon-containing material, thermal oxidation of granules with air at 30-60 C, carbonization at 700-950 C at temperature rise rate up to 50-80 C/min, and gas-vapor activation of carbonizate. Method can be used for preparing activated carbon with predominant diameter of micropores 0.85-0.95 nm and capable of adsorbing organic molecules with large molecule size (1.0-1.5 nm), which is appropriate for absorption of toxins and dioxins when treating animals and purifying foods and water. EFFECT: increased adsorption capacity. 2 tbl, 3 ex

Description

 The invention relates to the field of production of activated carbon (a.u.) and can be used to solve environmental problems (cleaning the soil from excess pesticides) and improve the quality of food products.

A known method for producing a.u., including grinding brown coal, pressing briquettes, their carbonization, crushing and activation at 800-900 ^o C (see patent GDR N 227946, 1985).

 The disadvantage of this method is the complexity of the carbonization process, the complexity of the briquetting process, the low quality of the obtained adsorbents.

Closest to the proposed technical essence and the achieved result is a method of obtaining a.u. by pressing the crushed carbon-containing material, carbonizing the granules to 550-650 ^o C at a speed of 20-25 deg / min, heating the carbonizate to 900-950 ^o C at a speed of 1-3 deg / min, activating with steam and crushing after activation to particle size 0.5 - 1.0 mm (see RF patent N 2023663, publ. 30.11.94, class C 01 B 31/08).

 The disadvantage of the prototype is the low adsorption capacity of the obtained a.u. when absorbing large organic molecules.

 Another disadvantage is the low yield of the finished product in relation to the taken raw materials.

 The aim of the invention is to increase the adsorption capacity of the obtained activated carbon in relatively large organic molecules - mycotoxins of the T-2 group (mol. Weight 466) in the treatment of broiler chickens in the process of growing them.

The goal is achieved by the proposed method, including pressing the crushed carbon-containing material, thermal oxidation of the granules at a temperature of 30-60 ^o C, their subsequent carbonization at 700-950 ^o C with a rate of temperature rise of 50-80 deg / min, activation in the environment of water vapor.

The difference of the proposed method from the prototype is that the "raw" granules after pressing are subjected to thermal oxidation with air at a temperature of 30-60 ^o C, which is carried out on a conveyor or belt dryer.

Another difference of the proposed method is to carry out accelerated (fast) carbonization, which is carried out after thermal oxidation at a temperature of 700-950 ^o C with a heating rate of 50-80 deg / min in the environment of the flue gases.

In the patent and other scientific and technical literature there is no description of the methods for producing activated carbons by thermal oxidation of raw granules at 30-60 ^o C.

An unknown method of carbonization of thermally oxidized granules at 700-950 ^o C, where heating is carried out at a speed of 50-80 deg / min.

 The essence of the proposed method is as follows.

They take the dust of a carbon-containing substance, for example, coal and semi-coke, mix it with a binder - various resins and granulate it into cylindrical granules on screw presses. Then the granules are fed to a conveyor (belt), which is blown with air heated to 30-60 ^o C. After thermal oxidation, the granules are sent to a rotating drum, which serves the flue gases. The temperature rise is carried out at a speed of 50-80 deg / min to 700-950 ^o C. Then the granules are cooled and fed to an activation furnace, for example, MPA or a rotary furnace, where the carbonizate is activated by water vapor by the reaction C + H ₂ O = CO + H ₂ to weight loss (burning), equal to 42-52%. After activation, the coal is cooled and analyzed.

и происходит усадка гранул за счет удаления влаги и легкокипящих масел связующего.In the proposed method, a porous structure is formed already in the process of thermal oxidation, when oxide-peroxide compounds of the type are formed on the surface of the granules

and shrinkage of the granules occurs due to the removal of moisture and low-boiling binder oils.

After thermal oxidation at relatively high temperatures of 700-950 ^o C and rapid heating in coals, a coarse-microporous structure with a radius of micropores r ₀ = 1.0-1.5 nm is formed, which provides an increased adsorption capacity of such a. at. for high molecular weight compounds such as mycotoxin T-2 with a molecular weight of 460 units.

 As a result of numerous experiments, it was found that as the obtained a.u. the temperature range of the oxidation of raw granules by air, the air supply rate and the oxidation time have a significant effect.

 Along with thermal oxidation, the temperature range of carbonization of thermally oxidized granules, the rate of temperature rise at this temperature, and the atmosphere at which carbonization is carried out have a huge impact on the quality of the obtained coals.

The authors found that the oxidation of granules with the above parameters (t = 30-60 ^o C, V = 0.05-010 m / s, τ = 2-3 h) makes it possible to form a dense skeleton with branched channels, which at relatively "fast" carbonization and high temperatures increase to sizes of 1.2 - 1.5 nm. Micropores of precisely these sizes provide high absorption efficiency of the obtained coals for relatively large and branched (non-linear molecules), such as T-2 mycotoxin.

 The following examples illustrate the invention.

 Example 1. Take 3.5 kg of coal brand SS (GOST 10355-76) and 3.5 kg of semi-coke long-flame coal grade D (GOST 5442-74), crushed in a ball mill to a particle size of 5-90 microns, and mix them with 3.0 kg of wood chemical resin (TU 13-4000-77-160-84) and 0.5 l of water.

The mixing process is carried out at a temperature of 50 ^o C for 1-3 minutes Then the paste is fed into the loading chamber of the screw press and granulation is carried out through spinnerets with a hole diameter of 1.0 mm.

Raw granules are thermally oxidized in a conveyor by air heated to a temperature of 30 ^o C for 2-3 hours at a speed of 0.05-0.10 m / s. Carbonization of the granules is carried out at 700 ^o C with a temperature rise rate of 50 deg / min in a rotary kiln in a flue gas stream.

Then carry out the activation at 950 ^o C water vapor, taken from the calculation of 3 kg of steam per 1 kg of activated carbon, burning - 42-52%.

 The absorption capacity of the obtained a.u. for mycotoxin T-2 is 95%, the safety of the number of chickens is 82%. Exit a.u. 45%

Example 2. Analogously to example 1, except that the thermal oxidation is carried out at 60 ^o C, and carbonization at 950 ^o C with a rate of temperature rise of 80 deg / min, activation is carried out to burns of 50-52%.

 The absorption capacity of the obtained a.u. for mycotoxin T-2 is 96%, the safety of the number of chickens is 84%. Exit a.u. 44%

Example 3. Analogously to example 1, except that the thermal oxidation is carried out at 45 ^o C, and carbonization is carried out at 825 ^o C with a temperature rise rate of 65 deg / min. Activation is carried out to burn 47%.

 The absorption capacity of the obtained a.u. for mycotoxin T-2 is 98%, the output of a.u. 45%

 In the table. Figure 1 presents examples illustrating the effect of temperature on the safety of chickens (due to the absorption of T-2 mycotoxin in their stomach with activated charcoal and its elimination in a natural way).

 Mycotoxin T-2 is ingested with poor-quality feed.

As follows from the obtained data, at oxidation temperatures of the raw granules in air equal to 30-60 ^o C, an increase in the adsorption capacity a is achieved. at. for mycotoxin T-2, which in turn increases the survival of broiler chickens by 23-28%. At these limits, an increase in yields a is also achieved. at.

When lowering the temperature of thermal oxidation below 30 ^o C are formed relatively small micropores, poorly removing mycotoxin T-2. An increase in temperature above 60 ^o C contributes to the development of very large (r ₀ more than 1.5 nm) micropores due to the burning of carbon walls, which also leads to a decrease in T-2 adsorption.

 In the table. 2 shows the results of the influence of both the carbonization temperature and the heating rate to a final temperature on the adsorption capacity of T-2 and the safety of chickens.

The experiments showed (Table 2) that the highest adsorption capacity for T-2 mycotoxin and the greatest safety of the chickens are achieved by carbonization in the temperature range 700-960 ^o C and a heating rate of 50-80 deg / min.

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:
increasing the adsorption capacity for large organic molecules, for example, T-2 mycotoxin, increasing the safety of the broiler chickens, the yields of the finished product, and the whole set is sufficient to characterize the claimed technical solution.

 The method is environmentally friendly, does not require scarce and expensive equipment, is provided with a raw material base - coal of the Kuznetsk basin. It solves the important national economic task of treating birds and protecting the environment.

Claims (1)

A method of producing activated carbon for detoxification of feed in poultry, including mixing crushed coal material with a resin binder, pressing granules, their carbonization and activation, characterized in that prior to carbonization, the granules are thermally oxidized with air at a temperature of 30-60 ^° С, carbonization is carried out at 700 - 950 ^o C with a rate of temperature rise to 50 - 80 ^o C / min, and activation is carried out before a burn of 42 - 52 wt.%.

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