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The introduction and the actuality of the topic
The coal is one of the most important types of the fuel and energy raw material. The main consumers of the coal in our country are thermoelectric power stations (42%), ferrous metallurgy (20%), boiler plants and housing and communal services (16%).
However there is the steady tendency to the increasing the content of the small classes and their ash values in the coal which are given for the enrichment. In usual coal the quantity of small classes with the size of 0,5 mm composes about 30 %. Besides, the additional sliming in the transportation and in other technological operations takes place.
That's why the problem of slime recycling is the most actual nowadays. Intensive fuel balance in Ukraine and negative ecological situation in our region demand the development of effective utilization ways of fine-grain, coal contained products from mine sludge pans and sludge tanks of concentrating factories which occupy the considerate areas and make worse sanitary condition of waters and atmosphere.
The range of sludge tanks are man-caused occurrences because of relatively removal low ash value from which it is possible to obtain energetic fuel and in some cases coking concentrate.
This fact gives the opportunity to further improvement of techniques and technologies for sliming recycling and development of new processes.
The purposes and tasks
The purpose of this work for sludge tank conditions in Makeevskij coking chemical plant is to develop the technology of concentrate separation which is suitable for coking and the technology of preparation of rest high ash value sludge tank part to the energetic usage.
The next tasks have been put for achievement of formulated purpose:
1. The research of physic-chemical properties of solid sludge tank phase and
definition of the most suitable its zones for recycling.
2. The development and calculation of the technological scheme of coking separation concentrate.
3. The research of nodulizing ways of high ash value removals and the definition of technological
regimes.
4. The development of technological granulated removal scheme.
5. Economical analysis.
The review of existed works according to the theme
The research results which obtained in National coal mining academy of Ukraine and in Ukraine SRI of coal-concentrating and the work experience of coal-concentrating factories allows to formulate the following main principles of coal sludge concentrating technology:
- the separation of high ash value slime part in case of separating to the size with
usage of high-frequency crashes with the size of particles sifting surface 0,1…..0,2 mm, small diameter
hydro cyclones, statistic hydraulic classifiers with mechanical unloading of grain part; in case of
high content of clay particles, for improvement of rheological properties of water coal suspension it
is necessary to dilute it by technical water and to water the grain part;
- in case of low ash value part the last one is for flotation or selected flocculation for additional
hot mass extraction;
- in case of high ash value part the last one is for flotation for additional hot mass extraction;
- in case of high ash value of grain part its separation is necessary to the firmness with the usage of
middle solid hydro cyclones ( by way of weighting material suspension is used as magnetite as the mixture
of milled solid pack cuts with pyrite which is contained in high ash value Donetsk coals), screw
separators, screw locks, conic separators, concentrated tables and other devices, which use the effects
appeared in the float of thin suspension layer on th solid surfaces; it is necessary to prefer simple
and less power-consuming, such as screw separators and screw locks;
- for effect separation increasing to the firmness the preparation of grained sludge part to the size
is necessary, for example, the rattling to 3 mm with return of oversize product into the jigging;
- for achievement of demanded concentrate moisture and additional removing from them the rest of high
ash value part it is desirable to dehydrate them in several receptions, for example, in turn in hydro
cyclones, on crashes and in centrifugals.
Conclusion
In the result of removal utilization stored in sludge tank of Makeevskij coking chemical plant the alternative fuel source for power engineering will be obtained, costs for sludge tank exploitation will be cut down. The grounds for sludge tank will be freed. The positive results of slime enrichment will be achieved to the given scheme: ash value in the limits 14%, clear profit - 13161,6 thousand griven per year, the term of project payback - 4 months.
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