The obtaining an adsorbent from coal of the field Shoptykol deposit of the Maykuben basin on experimental industrial installation

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The obtaining an adsorbent from coal of the field Shoptykol deposit of the Maykuben basin on experimental industrial installation

Abstract

in the article, experiments on heat treatment of coal at the Shoptykol deposit of the Maykuben basin were carried out by its carbonization and activation on a pilot-laboratory installation. First, carbonization of coal was carried out in an inert atmosphere of nitrogen in the temperature range of25-600 ° C and then the activation of coal with water vapor at a temperature of600 ° C for 1 hour. With the help of energy dispersive X-ray spectroscopy on a SEM instrument (Quanta 3D 200i) with an attachment for energy dispersive analysis from EDAX its chemical composition was determined. BET method determined adsorption characteristics of samples. It was found that the specific surface area and specific pore volume significantly increased as a result of high-temperature treatment of coal. Tests on testing the obtained activated carbon as an adsorbent for the purification of water and gas.

Keywords: coal, adsorbent, “Shoptykol”, carbonization, activation, cleaning.

Аннотация

Ермагамбет Болат Толеуханулы - доктор химических наук, профессор, директор;

Казанкапова Майра Куттыбаевна - РНР, ведущий научный сотрудник,

ТОО «Институт химии угля и технологии»;

Женисова Акмарал Камзиевна - магистрант,

Казахский университет технологии и бизнеса, младший научный сотрудник,

ТОО «Институт химии угля и технологии»;

Наурызбаева Асемай Турланцызы - магистрант,

Казахский университет технологии и бизнеса, младший научный сотрудник,

ТОО «Институт химии угля и технологии», г. Нур-Султан, Республика Казахстан

в статье проведены эксперименты по термической обработке угля месторождения «Шоптыколь» Майкубенского бассейна путем его карбонизации и активации на опытно-лабораторной установке. Сначала проводили карбонизацию угля в инертной среде азота в интервале температур 25-600 °С и затем активацию угля водяным паром при температуре 600 °С в течение 1 часа. С помощью энергодисперсионной рентгеновской спектроскопии на приборе SEM (Quanta 3D 200i) с приставкой для энергодисперсионного анализа от EDAX определен его химический состав. Методом БЭТ определены адсорбционные характеристики образцов. При этом установлено, что удельная поверхность и удельный объем пор существенно повышаются в результате высокотемпературной обработки угля. Проведены испытания по апробации полученного активированного угля в качестве адсорбента для очистки воды и газа.

Ключевые слова: уголь, адсорбент, «Шоптыколь», карбонизация, активация, очистка.

Due to the rapid development of "green energy", the production of solid fuels in the world, as energy raw materials is reduced. This leads to the search for highly efficient technologies for the complex processing of combustible minerals into products with high added value and high conversion, which is an urgent task for science and industry. Thus, the cost of carbon nanotubes in the world market ranges from $ 30 to $ 100 per 1 kg., the cost of nanosorbents is 450 times higher than the cost of raw materials with a huge market volume, and the total world production of porous carbon materials is currently about 1 million tons per year [1].

Activated carbon (activated carbon, "carbol") is a porous substance that is obtained from various carbon-containing materials of organic origin. Activated carbon contains a huge amount of pores and therefore has a very large specific surface area per unit mass, as a result of which it has a high adsorption.

The preservation of the planet's water resources is considered one of the main objectives of the development of modern science, and the purification of drinking and industrial wastewater is an important stage in its solution. There are various solutions to water purification methods, but the most simple and widely known is the adsorption method based on the use of solid sorbents. It should be noted that the level of production of domestic brands of carbon materials, suitable as adsorbents, remains not high. There are various schemes for obtaining carbon materials, which include the preparation and modification of the original coal, carbonization and subsequent activation by gas or chemical reagent.

The Maykuben lignite basin, which includes the Shoptykol, Sarykol, and Taldykol deposits, has been known since the beginning of the 19th century. Since 1941, coal has been developed on a small open-pit mine for local needs at the Shoptykol deposit, and since 1987, with a large open pit of Maykuben design capacity of 20 million tons/year.

The coals of the basin are humus, brown of a high degree of coalification (B3), medium salt (25-28%). Ash is refractory, with a high content of A12O3 (up to 30%), low-sulfur coals (0.5-1.0%) and polyphosphorous (0.1%). The heat of combustion to a combustible mass of 77.5 thousand kcal / kg. The yield of tar is 4-7%, rarely 10%, humic acids 5% on dry coal for Shoptykol suite and bitumen about 2.5%. The total reserves of coal in the basin are estimated at 5.3 billion tons, including those suitable for open pit mining with overburden up to 10 m3 / t are 1.8 billion tons [2].

As is known, the main characteristic of the adsorption capacity of materials during the adsorption of gases, vapor, solid and liquid substances is the surface development, the total pore volume, pore size distribution, high specific surface, which gives them a number of unique properties. Being an excellent sorption material, coal can be used for the purification of gases, liquid media, including sewage from petroleum products, phenols and salts of heavy metals.

The purpose of this work is to obtain porous carbon materials (adsorbents) based on coal from the Shoptykol deposit of the Maykuben basin for cleaning the gas phase from acidic components and wastewater.

Samples of activated carbon were obtained at the “Institute of Chemical and Coal Technology” LLP (Astana). Carbonization (at 600 °C in a nitrogen environment) and activation of water vapor in accordance with the procedure described in [3]. To obtain activated adsorbents, the previously obtained product is crushed to fractions of 0.1 mm, then crystalline samples are obtained from the extruder (d = 0.2-0.3 cm). The determined optimal composition of the adsorbent from the Shoptykol coal deposit, which amounted to (wt.%): Coal - 77.5; starch - 5; sodium hydroxide - 0.5; water - 17. Next, the product passes the stage of heat treatment (carbonization) and activation in an inert atmosphere of nitrogen (Figure 1). Samples should be obtained in the following way: final drying due to heat is obtained from the walls of the retort (final drying zone); distilling of volatile, resinous products and gaseous substances at a temperature of 450-600 °C (carbonization zone); activation due to the interaction of coal with superheated steam at a temperature of 600 °C for 1 hour (activation zone).

The main chemical reactions occurring in the activation zone:

2 H₂O ^ 2 H₂ + O₂-Q

C + H2O ^ CO + H2-Q

C + CO2 ^ 2 CO- Q

C + 2 H2 ^ CH4+Q

The first three reactions are dominant and take place with the absorption of heat. Therefore, to maintain the conditions for the reactions, an influx of heat is required, which occurs due to the combustion of gas in the furnace and the afterburning of activation gases in the collecting manifold.

Humidity, ash content and volatility of the samples were determined on a Thermoster Eltra thermogravimetric analyzer (according to ASTM D7582-12 Standard Test Methods for Thermogravimetric Analysis Standard Test Methods). The technical characteristics of the initial and activated adsorbent are (%): Ad - 23.44; W_r - 12.11; V_d - 40.66 and A_d - 16.97; W_r - 16.97; V_d - 32,10 respectively.

Chemical analysis of activated carbon was performed by energy dispersive X-ray spectroscopy on a SEM instrument (Quanta 3D 200i) with an attachment for energy dispersive analysis from EDAX. The energy of the exciting electron beam in the analysis was 15 kеV. The results of elemental analysis are presented in Тable 1.

Table 1. The chemical composition of activated carbon Maykuben basin

After carbonization, the number of elements such as carbon, oxygen and sulfur decreases, this is due to the fact that during the high-temperature treatment removes of volatile components (including burnout of unstructured carbon) occurs. At the same time, develop the structure of flat aromatic rings, uniting in graphite-like crystallites.

The adsorption characteristics of the samples (specific surface area, specific pore volume by limiting filling) were studied by the Brunauer-Emmett-Teller method (BET). The measurements were carried out on a KATAKON Sorbtometer M. The bulk density, the pH of the aqueous extract, the adsorption activity according to methyl orange was determined in accordance with the methods [4, 5].

The results of the study to determine the main physico-chemical characteristics of the original coal and activated adsorbent are shown in Table 2.

Table 2. Physical and chemical characteristics of the source and activated carbon of the Shoptykol deposit of the Maykuben basin