RU2531933C2 - Method of production of charcoal sorbent - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of charcoal sorbent to be used for production of active coals and carbon sorbents used in agriculture. Carbon-bearing stock (saw dust with initial moisture content of 10-30%) is carbonized at 450-600°C.Carbonised matter is activated by steam-gas mix at 650-800°C and cooled in thin bed to 20-30° at temperature decreased rate of 10°C/min. Obtained charcoal sorbent is subjected to additional activation for air oxygen oxidation.

EFFECT: invention allows production of charcoal sorbent that features iodine absorption capacity of 30-41% that complies with GOST requirements to DAK-grade ground active coal; continuous carbonisation-activation in one apparatus, porous structure of sorbents, required adsorption properties.

2 ex

Description

The invention relates to a method for producing a charcoal sorbent, which can be used to produce activated carbons and carbon sorbents used in agriculture (animal husbandry, poultry farming, soil cleaning, and also as a feed additive).

A known method of producing activated carbon [a. from. USSR N 1567515, class СВВ 31/08, September 28, 87, (1)] including grinding coal to a particle size of less than 0.5 mm and heating to 1000-1200 ° C, followed by activation at this temperature in a vortex furnace with an activating agent containing water vapor. The disadvantage of this method is the low total yield of the finished product (20-23%).

A known method of producing granular activated carbon [a. from. USSR N 1528729, class СВВ 31/10, 11.27.87, (2)] with an increased adsorption capacity of coal, on which brown coal is crushed, granulated in the presence of water, a layer of brown coal is rolled onto granules in the presence of a 12.5-25% aqueous solution of sulfite-alcohol mash , dried, carbonized and activated at 700-750 ° C for 20-30 minutes

The disadvantage of this method is the technological complexity in implementing the method on an industrial scale, the high cost of finished products.

Closest to the proposed method according to the technical nature and the achieved result is a method of producing activated carbon [a. from. USSR N 1020371, class СВВ 31/08, 09/29/80, (3)], selected for the prototype and including carbonization of ground carbon-containing wastes, water supply to carbonized wastes at a water flow rate of 0.4-0.8 m ³ per ton of waste, activation up to 700-750 ° C. The result is activated carbon with a specific surface area of 190-210 m ³ / g, density 1.5-1.9 g / cm ³ , strength 35%.

The disadvantages of this method include the following:

- grinding of raw materials;

periodicity of the process (separate stages of carbonization and activation, carried out sequentially in the same apparatus).

The objective of the invention is the use in the production of charcoal sorbents of renewable natural carbon-containing raw materials, such as sawdust, and the production of sorbents when used in the technological process of standard apparatuses.

A method of obtaining a charcoal sorbent, including the carbonization of carbon-containing raw materials at a temperature of 450-600 ° C and the subsequent activation of the carbonizate vapor-gas mixture at a temperature of 650-800 ° C.

As carbon-containing raw materials, sawdust of coniferous and deciduous species with an initial moisture content of 10-30% is used.

The obtained charcoal sorbent is sent for additional activation for oxidation by atmospheric oxygen.

The difference between the method is that the carbonization-activation process is carried out in one stage, in two stages. At the first stage, the decomposition of wood raw materials occurs with the formation of carbonizate and wood decomposition products, which are discharged from the reactor. At the second stage, the activation of hot carbonizate using a vapor-gas mixture is carried out.

The second difference is that in order to quickly and uniformly decompose the carbon-containing raw materials, given its low coefficient of thermal conductivity, the raw materials are fed into the reactor in the form of sawdust of hardwood and coniferous species evenly, in batches with a feed rate of 20 kg / h.

The third difference is that the obtained charcoal sorbent is sent for additional activation for oxidation by atmospheric oxygen.

The method is as follows. The crushed carbon-containing material (sawdust of deciduous and coniferous species of wood) is fed to the carbonization using a loading device, which is conducted in the first compartment of a rotary kiln at a temperature of 450-600 ° C for 20-30 minutes. The obtained carbonizate is sent for activation (second compartment of the furnace) at a temperature of 650-800 ° C with a steam-gas mixture at the rate of 3-12 kg of steam per 1 kg of carbonizate, after which the carbonizate is cooled. Cooling is carried out in a thin layer, and additional activation (oxidation by atmospheric oxygen) is carried out to a temperature of 20-30 ° C with a temperature reduction rate of 10 ° C / min.

The resulting activated carbon also had an iodine adsorption capacity of 30-41% (which corresponds to the requirements of GOST for crushed active coal grade DAK).

Example 1. 3.0 kg of sawdust of hardwood is sent to carbonization, which is carried out at a temperature of 500 ° C for 25 minutes The carbonate is activated with a gas-vapor mixture at a temperature of 800 ° C, the activation time is 40 minutes. The charcoal sorbent is cooled in a thin layer with atmospheric oxygen until a temperature of 20 ° C is reached at a rate of temperature decrease of 10 ° C / min. The yield of the final product is 22%. The iodine adsorption capacity is 38.8%.

Example 2. The process, as in example 1, except that carbonization is carried out at a temperature of 470 ° C, activation at a temperature of 740 ° C. The yield of the final product is 26%. The obtained charcoal sorbent had an iodine adsorption capacity of 28-31.1%.

As mentioned above, the development of the porous structure is carried out at the stage of activation, however, due to a decrease in temperature at the stage of cooling, this structure undergoes changes towards shrinkage. At a high rate of temperature decrease due to internal stresses, the crystallites of coal are destroyed and some micropores are eliminated, which contributes to a decrease in adsorption capacity. On the other hand, a slow decrease in temperature during cooling leads to a narrowing of the entrances to the sorbing pores and their blocking, as a result of which the adsorption capacity of activated carbon is reduced.

Thus, the proposed method allows to obtain a charcoal sorbent with an adsorption capacity for iodine of 30-41% (which meets the requirements of GOST for coal crushed active brand DAK). The use of wood waste from wood processing and lumbering (sawdust of coniferous and deciduous species) with a moisture content of 10-30% as a raw material. The proposed method allows to carry out a continuous process of obtaining a combined technological process of carbonization-activation of wood sawdust in one apparatus and at the same time to control the formation of the porous structure of the obtained charcoal sorbents during steam and gas activation and activation by air and to obtain sorbents with the required parameters of the porous structure and adsorption properties. A bench installation was made, technological parameters were tested, samples were developed, their analysis was carried out, and work is underway to identify the potential use of charcoal sorbent in animal husbandry to protect animals from the effects of toxic metabolites of microscopic fungi.

Information sources:

1. USSR author's certificate No. 1567515 from 09/28/1987 from 05/30/90 "Method for producing activated carbon."

2. USSR author's certificate No. 1528729 of 11.27.87 "Method for producing granular activated carbon."

3. USSR author's certificate No. 1020371 of 09.29.80 “Method for producing activated carbon” (prototype).

Claims (1)

A method of producing a charcoal sorbent, characterized in that the carbon-containing raw materials with a moisture content of 10-30% are carbonized at a temperature of 450-600 ° C, the steam-gas mixture is activated at 650-800 ° C at the rate of 3-12 kg of steam per 1 kg of carbonizate, the activated carbonizate is cooled in a thin layer (additional activation-oxidation by atmospheric oxygen) up to 20-30 ° C with a temperature reduction rate of 10 ° C / min.