Technical
sciences/1. Metallurgy
Abdrakhmanov Ye.S., Bykov P.Î., Bogomolov À.V., Kulumbayev N.Ê., Mukanov R.B.
Pavlodar State University named after S. Toraigyrov,
Kazakhstan
Ecological
aspects of use of Ekibastuz high-ash coal
Practical and
rational use of raw material resources to stimulate growth in industrial production
is one of basic requirements of Republic of Kazakhstan government in national
economy. One of progressive methods to solve this problem is lumping. Significance
of this study is extension of application field of Ekibastuz coal as an additive
while lumping ore.
Lumping is conversion
of fine-grained mineral resources into lump product due to mechanical and (or) thermal
influence with application of special additives or without them. Briquetting, a
physical and chemical process of processing of mineral resources, which is one
of modification of lumping, allows to obtain sorted product stable in
mechanical and thermal terms, namely, briquette with certain geometric shape, size
and weight. The main goal of briquetting is disposal of fine-grained mineral
resources and a chance to obtain high quality product out of them for household
and industrial use.
Republic of Kazakhstan ranks 8th place worldwide for coal
reserves. In Kazakhstan, 155 known coal deposits are explored and over 40 of
them are with about 35.8 bln. tons of commercial reserves (3.6 % of world reserves).
The most large coal basins are Ekibastuz (12.5 bln. tons), Karaganda (9.3 bln.
tons) and Turgai (5.8 bln. tons).
Ekibastuz coal basin is developed using open-cut mining method which in
its turn negatively affects the environmental situation of the region. Polluting
factors are stripping operations and spoil dump after them. One of the most
heavy polluting factors is transfer of coal dust and fines from open coal mines
and spoil dump by wind. Particles transferred are precipitated at nearby areas.
This fact is harmful to lands which are suitable for agricultural business.
Use
of coal dust and fines accumulated for production of coal briquette is one of
effective ways of solution of the problem.
Given the attractiveness of the idea, production of fuel briquette has
not such a long history. The whole idea has become actual and acute only in
recent years due to significant growth in fuel prices including coal products. Most
of the efforts to organize production of coal briquettes was brought to naught either
by expensive technology or low quality and bad characteristics of briquettes
obtained due to application of cheap and bad combustible binding agents which
greatly increased ash content and reduced sales effectiveness. The essence of
the idea is obtaining of briquettes from coal fines and dust of high-ash coal of
Ekibastuz deposit with possible subsequent coking.
The essence of the idea is obtaining of briquettes from coal fines and dust
of high-ash coal of Ekibastuz deposit with possible subsequent coking by
increase of carbon content, namely, in heating capacity. For this purpose, it
is planned to use the recently developed technology for obtaining technical
carbon by processing general mechanical rubber waste. Preliminary experiments
carried out clearly demonstrated suitability of technical carbon for upgrade of
fuel and coking briquettes. Thus, by the way, we solve the problem of disposal
of general mechanical rubber waste which is known to be the most popular type
of waste.
At the time being, one of the main problems of briquetting is impossibility
of getting of briquettes without adding non-combustible binding agents which in
their turn will far more increase ash content of briquettes. As a know-how of
this project it is analyzed a possibility of obtaining processed organic
products of bovine cattle byproducts as binding agents or some oil refining byproducts
which are combustibles and will not reduce percentage of briquette heating capacity.
According to
their intended use, coal briquettes divided into: household and industrial ones.
The main consumer
of household briquettes is population purchasing them in bulk or pre-packed in
bags with small weights. In order to provide appropriate thermal and mechanical
strength as well as smokelessness, briquettes
are undergone a heat treatment. Industrial briquettes are used as a raw
material for semi coking (brown coal) and coking (hardcoal and brown coal). Hardcoal
briquettes can serve as heat-insulating material and main raw material for manufacture
of different types of electrodes.
Perspective plans
for development of national economy pose important tasks for improvement of
briquette production. Firstly, it is study of simple and effective ways to
increase percentage and quality of coal briquettes produced and widening of their
application fields not only as a power plant and a household fuel but also as a
raw material for metallurgic process, semi coking, chemical processing.
Briquetting of
Ekibastuz coal fines with binding agents should be further used in creation of
new technologies for briquetting of composite materials of power plant and coking
coals. The special task for hardcoal briquetting is development of
cost-saving, cheap, non-toxic binding agents, attraction of binding agents of
mineral origin for this purpose and development of special additives, which
improve mechanical and thermal properties of briquettes. A new trend in lumping
of hardcoals before coking takes an essential role in briquetting of hardcoals.
In this case, non-sintering types of hardcoals can be used in coking stock. Briquetting provides maximum close contact of
coal particles and their compaction in briquettes. Briquetting is one of
perspective production trends providing high potential for fuel and energy sector,
iron and steel industry and non-ferrous metal industry, disposal of different
production wastes including general mechanical rubber goods.
Ekibastuz coal can contain about 46-67% of ballast. It means that when combusting
1 kg of coal the heat can be generated only by 54-33% of fuel, the rest turns
to ash. That is why coal before briquetting should be upgraded.
The method offered for upgrading of Ekibastuz coal is the method for
increase of carbon percentage in fuel by way of mixing of coal fine with smut. Mechanical
rubber and high quality smut contains 96-98 % of carbon.
For this purpose a developed technology is used to obtain carbon by
processing of mechanical rubber wastes. The experiments carried out clearly
demonstrated suitability of technical carbon for upgrading of fuel and coking briquettes.
As a result of mixing of coal fine and smut we reduced ash percentage in fuel down
to 15-17 %.
Implication of
this project has great perspectives in national and international scale. During
preliminary studies and analyzes of Ekibastuz coal by a team of authors it was
established that, in main volume, about 37% of coal extracted is 0.1-1.6 mm size
of coal fine. It allows to obtain fuel and coking briquettes with minimum costs
for their preparation which may suggest high practical importance for the
project and possibility of further commercialization.
Project results will be of interest to companies dealing
with coal extraction and sale of coal as well as to consumers who accumulate off-grade
coal fine.
References:
1
Bykhover N. À. Economics of mineral raw materials, v. 1-3. Ì., 1967-1971. World mineral resources. Ì.,
1997.
2
Republic of Kazakhstan government
decree of ¹644 of June 28, 2008. On prospective of coal industry development in
Republic of Kazakhstan up to
2020.
3
Palygunov P. P., Sumarokov Ì. V. Disposal of industrial waste. – Ì. : Stroiizdat, 1990. –
352 p. : il. – (Environmental protection).
4
Trozzi Ê., Berdovki Ya., Verkhoyev P., Weldt Ê., Pasina D.,
Jones H., Renz Î.,
Oertel D. and Woodfield Ì. Uncontrolled emissions of processes using solid
fuel: Conversion of solid fuel. Guidelines
of ÅÌÅÏ/ÅÀÎÑ for emission
inventory, 2009.
5
Kaliakparov
À. G., Ph.D. thesis in
Engineering Science - «Development of methods for alternative production and
use of carbonaceous reducing agent in Kazakhstan». –
Karaganda, 2010.