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Complex technology of processing of fly ash from brown coals
    Integrated waste technology waste heat power - Fly ash from the burning of brown coal Kansk-Achinsk basin.

Waste from the combustion of brown coal of high Kansk-Achinsk coal basin, located in the Krasnoyarsk region, are many millions of tons annually. Fly ash - and collected in electrostatic dust is one of the most "popular" objects of research in the environmental area, who devoted thousands of research papers in dozens of organizations of the former USSR and Russia. This is due to the fact that huge masses of waste collected directly near the mega-cities, alienating the expensive suburban land with the tendency of the nonlinear growth and significantly reducing the market value of nearby land and buildings. Due to the high content of alkali and water-soluble sulfates pressure on the environment (water and air swimming pool, the surrounding landscape) is very large.

Ash dumps require a huge maintenance costs. The share of the costs of transporting wet waste ash dump and his service in the tens of% in the cost of the actual end products TPP - electricity and heat. However, the full cabinet "D" for disposal of ash ablation failed and could not give any positive effect (only negative because of the huge costs of research). There are a number of reasons:

1. in the former USSR the problem of monopoly engaged in the construction of "science", as well as energy, which by the nature of his activities could not solve complex interdisciplinary problems;

2. the problem is complex, and any partial solutions are doomed to failure because of the huge masses of waste and problems with transportation;

3. without market relations and related infrastructure attempts to solve the problem of disposing of ash were purely voluntaristic character;

4. fly ash - a typical heterogeneous mixture, all the attempts of its use in the manufacture of building materials as a whole is doomed to failure because of the unstable structure and components for various applications;

5. on the world market is not still an effective technique for the separation of large-tonnage thin heterogeneous mixtures - common technique type centrifugal classifier requires the capture of fine dust at the exit, but it is technically and economically feasible in certain principles;

6. high content of calcium oxide limits the main area of waste ash ash - concrete and plaster, while low activity of the hydration of free calcium oxide grains leads to a local increase in volume within the hardened stone, the appearance of internal stresses and its destruction from within.

Thus, the problem of disposal of fly ash has several components:

A) The technical problem of separation of heterogeneous mixtures;

B) search and development of technologies for utilization of allocated components of ash ash;

C) create a market for products from the ashes - huge masses of new products may not be immediately perceived by the market, especially the cheap because of the limited capacity of the local market;

D) time - the production of ash is mainly in the heating period, and consumption - in the summer construction season;

E) organization - the problem is impossible without a coherent policy of regional authorities, RAO UES, thermal power plants, construction companies, as well as trained individual builders.

The most difficult problem in Russia of the above - the last, but for the successful implementation of the project as a whole must be flexible and interrelated decision of all components.

A. The technical solution to the problem of separation of ash carryover.

For the separation of thin materials developed a unique, having no analogues in the world of eco-technology with a common name Elektromassklassifier (EMC). The principle of the multi-purpose technology for dry processing of thin materials based on the mechanochemical phenomenon of "gas-dust plasma" - a dense aerosol and charged particles. Generation and separation of the internal electric fields of aerosol leads to the possibility of obtaining an unlimited number of factions in a confined space, ie without the use of filters, cyclones, compressors, etc. The simplicity of design EMC and low operating costs (2-3 times lower than that of technology, which solves a similar problem) for the first time make possible the processing of a lot of tonnage of dry waste and minerals. Dust control material allows separation of heterogeneous material on other parameters: the magnetic, electrical, density, shape and even color of the particles. Some of the elaborated separators also do not have yet in the world. Repose of schema processing brown coal ash has now been obsolete since the last 15 years has changed the market structure.

B. Technologies and Products from the ashes of ash.

The bulk of the ash is 40-50% in the ash concrete mark 200 (small additive cement stabilizes the lower limit of strength). The main profit of the process provides expensive spherical fractions, which can be used to produce powders for copiers - developers and toners. Their potential value is many times the actual price of raw coal. To extract the spherical particles> 20 microns from the magnetic fractions developed a special separator, which is unparalleled in the world market.
Other by-products:

- Cox in the amount of 3-5% (returns to the burning of the pot),

- 6-10% magnetite (raw material for steel),

- Special black pigment 1-2%,

- 30-40% of the material for building and plaster solutions with high plasticity.

C. Creating a market for products from the ashes.

The main challenge is recycling the bulk of the ash. Cheap concrete on the basis of mechanically activated ash binder has a number of features. The first is due to slow recruitment strength in the first few days after mixing, as well as the need to use in 2-7 days after activation and supplements of calcium chloride solution for the chemical activation of glasses and the binding of calcium sulfate. Optimum shelf life is associated with an increase in activity in the first days after activation EMC, as well as with the aging of the material due to interaction with moisture and carbon dioxide. Slow hardening makes it a little demand (only as a supplement of about 15-30% to reduce the consumption of cement) and conventional concrete plants, producing load-bearing concrete slabs with an accelerated curing process for the rapid turnover of the formwork. However, these features do not interfere with the use of ash binder in individual housing for bezarmaturnyh small concrete blocks, as well as in the construction of local roads and pavements of the same blocks, paving slopes of bridges and dams.

Low cost of the concrete produced in huge quantities directly in the megalopolis of binder stimulate construction, primarily individual and road. To achieve a large mass of material in individual housing should be made available, and other basic materials mean the Russians had been done in the framework of the Eco House, which won first prize at the All-Russian competition "My house" in 1996. The construction of local roads and pavements, which are severely lacking and which are in terrible condition, is entirely in the hands of local authorities, concerned to put it mildly, their problems.

D. The problem of time mismatch in the production of ash and consumption of products from the bulk ash.

To implement the project requires disposal of ash, dry ash in the selection of silage and its processing throughout the year. For example, the TPP-3 Novosibirsk volume of silage significantly less than the annual volume of production. The peculiarity of ash that can be stored without changing the properties for a year or even more. But after processing, including the stage of mechanical activation of the surface, it gets increased activity within 2-4 days and then starts to age, up to a level below the original activity. Thus, given the lack of silos at the huge amount of ash produced mostly in the winter time, you must carry part of the ashes of local consumers for their storage and local processing at the right time.
Appliances EMC relatively simple and inexpensive, the standard model , and therefore able to provide such a scenario disposal of ash with a large number of individual consumers - the potential developers. Centralized processing of ash on the full scheme can be near the place of its production and during its production, but needs to optimally manufacture of final products - concrete blocks.
feature ash binder - slow recruitment strength, in this scenario does not play a negative role, as set strength within a year or more (up to 2-2,5 times higher than in the control period of 4 weeks for conventional concrete) added to low Price is another major advantage - high strength at the time of use blocks in the construction.

E. Organizational problem

- Linking the activities of local authorities with the owners of various forms of ownership and individual consumers.

This problem is due to the specifics of Russia and its recent transition to market economy principles, the mentality of officials, is the most complex, and the opportunity to address it difficult to predict. For example, the authorities often "support" of local producers, offering their services, obsolete for half a century for all positions. The new production takes market share from such "producers".

Experience of cooperation with the energy sector-a monopoly is not a basis for optimism, because not always have a clear interest. Technology can eliminate the negative effects of fluctuations of active component in the ash 3 times (much more than require foreign and domestic standards), but import of coal from different sections (such as Berezovsky and the Borodino) may bring some variation in composition to ridiculous 10 times.

The main potential consumer of binders from the ashes, or pre-cast concrete blocks - the road sector. Emphasis is placed on the main roads and highways, construction of which should lead to the most stringent standards. However, in Siberia, a huge number of dirt roads, which are in existing facilities in the USSR, the construction industry will never turn. The use of concrete blocks for the construction of seasonal local roads solves many problems, but it will not please everybody. Lobbyists can use imperfect standards and the judicial system to stop such construction.

The engine for the solution of the problem is the individual developers, especially united in the condominiums. However, cheap basic materials for the mass construction require the addition of modern projects, engineering equipment for the home, rapid technology construction season.

More detailed and current information about technology for the processing of ash from brown coal you can get by purchasing our book (in Russian): Fly ash - technogenic raw material.

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