Equipment for the production of wood ash. Fly ash: description, composition, state standard specification, application features and reviews. Approximate doses, terms and methods of applying an agrochemical in personal subsidiary plots

Energy companies Krasnoyarsk Territory and the Republic of Khakassia, which are part of the Siberian Generating Company group, in 2013 sold and brought into economic circulation 662,023 thousand tons of ash and slag waste (ASW).

During the year, the Krasnoyarsk branch of SGC increased the volume of involvement of ASW in the economic turnover by 4% - from 637,848 thousand tons in 2012 to 662,023 thousand tons in 2013.

The growth in the economic turnover of ash and slag waste (a by-product of coal combustion at thermal power plants) allows reduce the load on environment in the cities where the company operates. It should be noted that the main volume of ash and slag waste (625.5 thousand tons) last year was directed to the sale of a large environmental project for the reclamation of ash dump No. 2 at Nazarovskaya GRES. The reclamation of an exhausted ash dump with an area of ​​160 hectares, located in the area of ​​the Chulym River, will allow these lands to be returned to economic circulation. For example, after a few there may appear green spaces.

In addition, the Krasnoyarsk branch of SGC continues to sell ash and slag waste to construction industry enterprises. The company started selling dry ash and slag for the first time in 2007. Then only 7 thousand tons of waste were sold. In 2013, sales volumes amounted to 36,525 thousand tons of ash and slag waste. Thus, the average annual volumes of ash and slag waste sales have increased over the 6 years of operation in this market more than five times. T This increase in demand indicates that builders highly appreciated this type of raw material. At the same time, ash and slag waste is bought not only by enterprises from the Krasnoyarsk Territory, but also from other regions of Russia.

Thanks to the active work of SGC in this direction, last year the volume of ASW sold and involved in the economic turnover (662,023 thousand tons) turned out to be 34% higher than the amount of ash and slag waste generated by the energy enterprises of the branch (495 thousand tons).

In 2014, the Krasnoyarsk branch of SGC will continue to work on the involvement of ash and slag waste in the economic turnover, thereby reducing their accumulation and reducing the load on the environment. Work will continue on the reclamation of ash dump No. 2 at Nazarovskaya GRES. In addition, the company is considering the possibilities and expanding markets sale of dry ash and slag and for the needs of not only the construction industry, but also other industries.

The use of ash and slag waste from thermal power plants in construction

A lot of ash and slag waste is generated in the process of activity of electric power industry enterprises. The annual flow of ash to ash dumps in Primorsky Krai is from 2.5 to 3.0 million tons per year, Khabarovsk - up to 1.0 million tons (Fig. 1). Only within the city of Khabarovsk, more than 16 million tons of ash are stored in ash dumps.

Ash and slag waste (ASW) can be used in the production of various concretes, mortars, ceramics, thermal and waterproofing materials, road construction, where they can be used instead of sand and cement.
Dry fly ash from electrostatic precipitators of CHPP-3 finds greater application. But the use of such wastes for economic purposes is still limited, including due to their toxicity. They accumulate a significant amount of dangerous elements.
Dumps constantly generate dust, mobile forms of elements are actively washed out by precipitation, polluting the air, water and soil.
The use of such waste is one of the most actual problems. This is possible by removing or extracting harmful and valuable components from the ash and using the remaining mass of ash in the construction industry and the production of fertilizers.

Brief description of ash and slag waste

At the surveyed thermal power plants, coal is burned at a temperature of 1100-1600o C.
During the combustion of the organic part of coals, volatile compounds are formed in the form of smoke and steam, and the non-combustible mineral part of the fuel is released in the form of solid focal residues, forming a dusty mass (ash), as well as lumpy slags.
The amount of solid residues for hard and brown coal ranges from 15 to 40%.

Coal is crushed before burning and, for better combustion, fuel oil is often added in a small amount of 0.1-2%.
During the combustion of crushed fuel, small and light particles of ash are carried away by flue gases, and they are called fly ash. The particle size of fly ash ranges from 3-5 to 100-150 microns. The amount of larger particles usually does not exceed 10-15%.

Fly ash is captured by ash collectors.
At CHPP-1 of Khabarovsk and Birobidzhanskaya CHPP, ash collection is wet on scrubbers with Venturi pipes, at CHPP-3 and CHPP-2 of Vladivostok, dry ash collection is done on electrostatic precipitators.
Heavier ash particles settle on the fireboxes and are fused into lumpy slags, which are aggregated and fused ash particles ranging in size from 0.15 to 30 mm.
Slags are crushed and removed with water. Fly ash and crushed slag are first removed separately, then mixed, forming an ash and slag mixture.

In the composition of the ash and slag mixture, in addition to ash and slag, particles of unburned fuel (underburnt) are constantly present, the amount of which is 10-25%. The amount of fly ash, depending on the type of boilers, type of fuel and the mode of its combustion, can be 70-85% by weight of the mixture, slag 10-20%.
Ash and slag pulp is removed to the ash dump through pipelines.
Ash and slag during hydrotransport and at the ash dump interact with water and carbon dioxide.
They undergo processes similar to diagenesis and lithification. They quickly succumb to weathering and when drained at a wind speed of 3 m / s, they begin to dust.
The color of the ASW is dark gray, layered in the section, due to the alternation of uneven-grained layers, as well as the deposition of a white foam consisting of aluminosilicate hollow microspheres.
The average chemical composition of the ASW of the surveyed CHPPs is given in the following table 1.

Table 1. Limits of the average content of the main components of ASW

The content of Ni, Co, V, Cr, Cu, Zn is not more than 0.05% of each element.
Due to their regular spherical shape and low density, microspheres have the properties of an excellent filler in a wide variety of products. Promising directions industrial use aluminosilicate microspheres are the production of spheroplastics, road-marking thermoplastics, grouting and drilling fluids, heat-insulating radio-transparent and lightweight building ceramics, heat-insulating unfired materials and heat-resistant concretes.

Abroad, microspheres are widely used in various industries. In our country, the use of hollow microspheres is extremely limited and they, together with the ash, are dumped into ash dumps.
For thermal power plants, microspheres are a "harmful material" that clogs the pipes of circulating water supply. Because of this, it is necessary to completely replace pipes in 3-4 years or carry out complex and expensive work to clean them.

The inert mass of the aluminosilicate composition, which is 60-70% of the mass of ASW, is obtained after the removal (extraction) from the ash of all the above concentrates and useful components and heavy fraction. In composition, it is close to the general composition of ash, but it will contain an order of magnitude less glands, as well as harmful and toxic.
Its composition is mainly aluminosilicate. Unlike ash, it will have a finer uniform granulometric composition due to grinding when extracting the heavy fraction.
According to environmental and physico-chemical properties, it can be widely used in production building materials, construction and as a fertilizer - a substitute for lime flour (ameliorant).

The coals burned at the thermal power plant, being natural sorbents, contain impurities of many valuable elements (Table 2), including rare earths and precious metals. When burned, their content in the ash increases by 5-6 times and may be of industrial interest.
The heavy fraction recovered by gravity using advanced concentration plants contains heavy metals, including precious metals. By fine-tuning, precious metals are extracted from the heavy fraction and, as they accumulate, other valuable components (Cu, rare, etc.).
The output of gold from individual studied ash dumps is 200-600 mg per ton of ASW.
Gold is thin, non-recoverable by conventional methods. Know-how technology is used to extract it.

Many people are involved in the disposal of ASW. More than 300 technologies for their processing and use are known, but they are mostly devoted to the use of ash in construction and the production of building materials, without affecting the extraction of both toxic and harmful components, and useful and valuable ones.

We have developed and tested in laboratory and semi-industrial conditions a basic scheme for the processing of ASW and their complete disposal.
When processing 100 thousand tons of ASW, you can get:
- secondary coal - 10-12 thousand tons;
- iron ore concentrate - 1.5-2 thousand tons;
- gold - 20-60 kg;
- building material (inert mass) - 60-80 thousand tons.

In Vladivostok and Novosibirsk, ASW processing technologies similar in type have been developed, possible costs have been calculated, and the necessary equipment has been provided.
Extraction of useful components and complete utilization of ash and slag waste through the use of their useful properties and the production of building materials will free up space and reduce the negative impact on the environment. Profit is desirable, but not the decisive factor.
The costs of processing technogenic raw materials with the production of products and simultaneous neutralization of waste may be higher than the cost of products, but the loss in this case should not exceed the costs of reducing the negative impact of waste on the environment. And for energy enterprises, the utilization of ash and slag waste is a reduction in technological costs for the main production.

Literature

1. Bakulin Yu.I., Cherepanov A.A. Gold and platinum in ash and slag waste from the CHPP of Khabarovsk // Ores and Metals, 2002, No. 3, pp. 60-67.
2. Borisenko L.F., Delitsyn L.M., Vlasov A.S. Prospects for the use of ash from coal-fired thermal power plants./JSC "Geoinformmark", M.: 2001, 68p.
3. Kizilshtein L.Ya., Dubov I.V., Spitsgauz A.P., Parada S.G. Components of ashes and slags from thermal power plants. Moscow: Energoatomizdat, 1995, 176 p.
4. Components of ashes and slags from thermal power plants. Moscow: Energoatomizdat, 1995, 249 p.
5. Composition and properties of ash and slag from thermal power plants. Reference manual, ed. Melentyeva V.A., L.: Energoatomizdat, 1985, 185 p.
6. Tselykovsky Yu.K. Some problems of using ash and slag waste from thermal power plants in Russia. Power engineer. 1998, No. 7, pp. 29-34.
7. Tselykovsky Yu.K. Experience in the industrial use of ash and slag waste from thermal power plants // New in the Russian energy sector. Energoizdat, 2000, No. 2, pp. 22-31.
8. Valuable and toxic elements in commercial coals of Russia: Handbook. M.: Ne-dra, 1996, 238 p.
9. Cherepanov A.A. Ash and slag materials// Main problems of study and mining mineral raw materials Far East economic region. The mineral resource complex of the FER at the turn of the century. Section 2.4.5. Khabarovsk: Publishing House of DVIM-Sa, 1999, pp. 128-120.
10. Cherepanov A.A. Noble metals in ash and slag waste from Far Eastern thermal power plants // Pacific Geology, 2008. V. 27, No. 2, pp. 16-28.

V.V. Salomatov, Doctor of Technical Sciences Institute of Thermal Physics SB RAS, Novosibirsk

Ash and slag waste from thermal power plants on Kuznetsk coal and ways of their large-scale utilization

Processing scale solid waste coal thermal power plants are extremely low today, which causes the accumulation of huge amounts of ash and slag in ash dumps, requiring the withdrawal of large areas from circulation.

Meanwhile, Kuznetsk coal ash and slag contains valuable components such as Al, Fe, rare metals, which are raw materials for other industries. However, with traditional methods of burning these coals, it is not possible to on a large scale to use ash and slag, as due to the formation of mullite, they have a high abrasiveness and are chemically inert to many reagents. Attempts to use ash and slag of such a mineralogical composition in the production of building materials lead to intensive wear of technological equipment and a decrease in productivity due to a slowdown in the physical and chemical processes of the interaction of ash components with reagents.

It is possible to avoid mullitation of Kuznetsk coal ash by changing the temperature conditions of their combustion. Thus, the use of a fluidized bed for burning coal at 800–900 °C makes it possible to obtain less abrasive ash, and its main mineralogical phases will be metakaolinite, ?Al2O3; quartz, glass phase.

Utilization of ash and slag wastes from CHP plants at low-temperature combustion of CHP

The amount of ash and slag waste from the most typical thermal power plant with an electric power of 1295/1540 MW and a thermal power of 3500 Gcal/h is about 1.6...1.7 million tons per year.

The chemical composition of Kuznetsk coal ash:

SiO2 = 59%; Al2O3 = 22%; Fe2O3 = 8%; CaO = 2.5%; MgO = 0.8%; K2O = 1.4%; Na2O = 1.0%; TiO2 = 0.8%; CaSO4 = 3.5%; C = 1.0%.

The use of Kuznetsk coal ash is most effective in the production of aluminum sulfate and alumina using the technologies of the Kazakh Polytechnic Institute. Based on the material composition of the KU ash and its quantity, the recycling scheme is shown in Figure 1.

Only 6 special types of alumina are produced in Russia, while only in Germany - about 80. Their range of applications is very wide - from the defense industry to the production of catalysts for the chemical, tire, light and other industries. The needs for alumina in our country are not covered by our own resources, as a result of which part of the bauxite (raw material for the production of alumina) is imported from Jamaica, Guinea, Yugoslavia, Hungary and other countries.

The use of Kuznetsk coal ash will make it possible to somewhat rectify the situation with a deficiency of aluminum sulfate, which is a means for treating waste and drinking water, as well as used in large quantities in the pulp and paper, woodworking, light, chemical and other sectors of industry. Aluminum sulfate deficiency only in the region Western Siberia is 77...78 thousand tons.

In addition, the dispersed composition of alumina obtained after sulfuric acid processing makes it possible to obtain various types of special alumina, the need for which will be satisfied to a certain extent if they are produced in an amount of 240 thousand tons.

Wastes from the production of aluminum sulfate and alumina are a raw material for the production of water glass, white cement, binders for backfilling mined-out mining areas, container and window glass.

The need for these materials is increasing, and the demand for them now significantly exceeds their production volumes. Approximate technical and economic indicators of these industries are presented in Table 1.

Table 1. Main technical and economic indicators for the processing of ash from Kuznetsk coals

In addition, it is expedient to produce rare and dispersed metals from the ash of the KU, primarily gallium, germanium, vanadium and scandium.

Due to the fact that the CHPP, according to the conditions of its schedule, operates with a variable load throughout the year, the ash output is uneven. Ash processing plants should work rhythmically. Storage of dry ash presents certain difficulties. In this regard, it is proposed winter time send part of the ash for granulation using pelletizers manufactured by Uralmash. After pelletizing and drying, the granules are fired in the boiler furnace, and then they are sent by pneumatic transport for temporary storage in a dry warehouse. Ash pellets can later be used as a raw material base for the construction industry or used in road construction.

Storage of pellets in an open dry warehouse does not require special protective measures and does not create a dusting hazard. The capacity of such an ash dump is about 350...450 thousand tons, the area is about 300?300 m2. Therefore, it may be located in close proximity to the CHP site.

Ash and slag waste obtained after combustion of CFB in boiler units with a circulating fluidized bed (CFB), which Russia does not yet produce, will have the best utilization rates. CFB boilers provide not only a sharp reduction in emissions of nitrogen and sulfur oxides, but also produce ash and slag waste, which can be successfully used in industry to produce alumina and building materials. This makes it possible to reduce the cost of the power plant due to a sharp reduction in the areas necessary for storing ash, and to reduce environmental pollution. Dust reduction at CHPPs with CFB boilers occurs, firstly, due to a decrease in the area of ​​the ash dump, and secondly, due to the fact that the ash obtained by burning Kuznetsk coal in the CFB contains gypsum and has astringent properties. With some wetting of such ash, it will harden, which will eliminate dusting even if the ash dump dries up.

As the ash is transported to industrial enterprises pneumatic transport, water consumption is also slightly reduced. In addition, there is no wastewater from the ash dump, which at CHPPs with traditional pulverized coal boilers contains salts of heavy metals and other harmful substances.

Production of aluminum sulfate and alumina

The technology for producing aluminum sulfate and alumina based on low-temperature combustion ash is shown in Figure 2.

The optimal conditions for the implementation of this technology are as follows:

• coal burning ( temperature regime 800…900 °C);
• grinding (grinding fineness - 0.4 mm (at least 90%);
• sulfuric acid opening (temperature 95 ... 105 ° C, duration 1.5 ... 2 hours, sulfuric acid concentration 16 ... 20%);
• separation of liquid and solid phases (filter fabric article L-136, rarefaction 400…450 mm Hg, suction filter 0.37…0.42 m3/m2?h);
• two-stage sludge washing;
• hydrolytic decomposition (temperature 230 °C, time 2 hours);
• thermal decomposition (temperature 760…800 °C).

The resulting production aluminum sulfate (50 thousand tons per year) after granulation and packaging in plastic bags is sent to consumers. The performed feasibility study shows the feasibility of aluminum sulfate production based on low-temperature combustion ash.

Ash-derived aluminum sulfate is a good coagulant for industrial wastewater treatment.

Sishtof after sulfuric acid treatment due to the low content of iron oxides (less than 0.5 ... 0.7%) is a substitute for sand in the production of white cement, and the presence of 4 ... 6% gypsum in it will intensify the processes of cement production themselves.

Production of ferroalloys and building materials

The production of ferroalloys based on the mineral part of coals has been thoroughly developed. Testing of industrial technologies for the production of ferrosilicoaluminum and ferrosilicon from ash and slag waste, similar in composition to Kuznetsk coal ash and its magnetic component, which can be isolated by magnetic separation methods, was carried out. The resulting alloys were tested on an industrial scale at the metallurgical plants of the country for the deoxidation of steel and positive results.

Obtaining building materials based on sishtof does not require changes in the existing technologies of these industries. Sishtof is used as a raw material and replaces quartz and other silicon-containing products used in the production of building materials. In addition, silicon oxide, the content of which in sistof is 75–85%, is presented mainly in the form of amorphous silica with high chemical activity, which makes it possible to predict an improvement in the performance and quality of cement and binders. The minimum amount of ferruginous and other coloring compounds in sistof makes it possible to obtain white cement on its basis, the need for which is very high.

Technologies for producing cement, binders, and liquid glass have also been developed in industry.

Conclusion

Ash and slag wastes obtained by burning Kuznetsk coal in power steam generators using the circulating fluidized bed technology, which is new for Russia, are in demand for large-scale disposal. It is economically efficient to produce very scarce ferroalloys, aluminum sulfate, special types of alumina, liquid glass, white cement, and binders using technologies already mastered in the industry.

Bibliography Salomatov V.V. Environmental technologies based on thermal and nuclear power plants: monograph / V.V. Salomatov. - Novosibirsk: publishing house of NGTU, - 2006. - 853 p.

74rif.ru/zolo-kuznezk.html, energyland.info/117948

During the combustion of fuel, waste products are formed, which are called fly ash. Special devices are installed next to the furnaces to trap these particles. They are a dispersion material having components smaller than 0.3 mm.

What is fly ash?

Fly ash is a finely dispersed material with small particle sizes. It is formed during the combustion of solid fuels under conditions elevated temperatures(+800 degrees). It contains up to 6% of the unburned substance and iron.

Fly ash is formed during the combustion of mineral impurities that are in the fuel. For different substances, its content is not the same. For example, in firewood, the content of fly ash is only 0.5-2%, in fuel peat 2-30%, and in brown and hard coal 1-45%.

Receipt

Fly ash is formed during the combustion of fuel. The properties of the substance obtained in boilers differ from those created in the laboratory. These differences affect the physico-chemical characteristics and composition. In particular, when burning in a furnace, the mineral substances of the fuel melt, which leads to the appearance of components of an unburned composite. Such a process, which is called mechanical underburning, is associated with an increase in the temperature in the furnace to 800 degrees and above.

To capture fly ash, special devices are needed, which can be of two types: mechanical and electrical. During the operation of the main memory, it is spent a large number of water (10-50 m 3 of water per 1 ton of ash and slag). This is a significant disadvantage. To get out of this situation, a circulating system is used: water, after being cleaned from ash particles, re-enters the main mechanism.

Main characteristics

• Workability. The finer the particles, the greater the effect of fly ash. The addition of ash increases the homogeneity of the concrete mixture and its density, improves laying, and also reduces the consumption of mixing water with the same workability.
• Reducing the heat of hydration, which is especially important in the hot season. The ash content in the solution is proportional to the decrease in the heat of hydration.
• capillary absorption. Adding 10% fly ash to cement increases the capillary absorption of water by 10-20%. This, in turn, reduces frost resistance. To eliminate this shortcoming, it is necessary to slightly increase the air entrainment due to special additives.
• Resistant to aggressive water. The cements, which are 20% ash, are more resistant to immersion in aggressive water.

Pros and cons of using fly ash

The addition of fly ash to the mixture entails a number of advantages:

• Clinker consumption is reduced.
• Grinding improves.
• Strength increases.
• Improved workability, which facilitates stripping.
• Shrinkage is reduced.
• Reduces heat generation during hydration.
• The time before the appearance of cracks increases.
• Improves resistance to water (both clean and aggressive).
• The mass of the solution is reduced.
• Increases fire resistance.

Along with the advantages, there are some disadvantages:

• The addition of ash with a high content of underburning changes the color of the cement mortar.
• Reduces initial strength at low temperatures.
• Reduces frost resistance.
• The number of mixture components that need to be controlled increases.

Types of fly ash

There are several classifications by which fly ash can be divided.

According to the type of fuel that is burned, ash can be:

• Anthracite.
• Carboniferous.
• Brown coal.

According to their composition, ash is:

• Acidic (with calcium oxide content up to 10%).
• Basic (content above 10%).

Depending on the quality and further use, 4 types of ash are distinguished - from I to IV. Moreover, the latter type of ash is used for concrete structures, which are used in difficult conditions.

fly ash processing

For industrial purposes, untreated fly ash is most often used (without grinding, screening, and so on).

When fuel is burned, ash is formed. Light and small particles are carried away from the furnace due to the movement of flue gases and are captured by special filters in the ash collectors. These particles are fly ash. The rest is called dry selection ash.

The ratio between these fractions depends on the type of fuel and design features the firebox itself:

• with solid removal, 10-20% of ash remains in the slag;
• with liquid slag removal - 20-40%;
• in cyclone-type furnaces - up to 90%.

During processing, particles of slag, soot and ash can enter the air.

Dry fly ash is always sorted into fractions under the influence of electric fields that are created in the filters. Therefore, it is the most suitable for use.

To reduce the loss of matter during calcination (up to 5%), fly ash is necessarily homogenized and sorted into fractions. The ash that is formed after the combustion of low-reactive coals contains up to 25% of the combustible mixture. Therefore, it is additionally enriched and used as an energy fuel.

Where are fly ash used?

Ashes are widely used in various fields life. It can be construction, agriculture, industry, sanitation

Fly ash is used in the production of certain types of concrete. Application depends on its type. Granulated ash is used in road construction for the foundation of parking lots, solid waste storage sites, bicycle paths, embankments.

Dry fly ash is used to strengthen soils as an independent binder and quickly hardening substance. It can also be used for the construction of dams, dams and other

For production, ash is used as a substitute for cement (up to 25%). As a filler (fine and coarse), ash is included in the process in the production of cinder concrete and blocks used in the construction of walls.

Widely used in the production of foam concrete. The addition of ash to the foam concrete mixture increases its aggregative stability.

Ashes in agriculture are used as potash fertilizers. They contain potassium in the form of potash, which is easily soluble in water and available to plants. In addition, the ash is rich in other useful substances: phosphorus, magnesium, sulfur, calcium, manganese, boron, micro and macro elements. The presence of calcium carbonate allows the use of ash to reduce soil acidity. Ash can be applied for various crops in the garden after plowing, it can be used to fertilize tree and shrub circles around the trunks, as well as to add meadows and pastures. It is not recommended to use ash simultaneously with other organic or mineral fertilizers (especially phosphate fertilizers).

The ash is used for sanitation in the absence of water. It increases the pH level and kills microorganisms. It is used in latrines, as well as in places of sewage sludge.

From all of the above, we can conclude that a substance such as fly ash is widely used. The price for it varies from 500 r. per ton (with large wholesale) up to 850 rubles. It should be noted that when using self-delivery from distant regions, the cost may vary significantly.

GOSTs

Documents that control the production and processing of fly ash have been developed and are in force:

• GOST 25818-91 "Fly ash for concrete".
• GOST 25592-91 "Ash and slag mixtures for TPPs for concrete".

Other additional standards are used to control the quality of the produced ash and mixtures with its use. At the same time, sampling and all types of measurements are also carried out in accordance with the requirements of GOSTs.

As it often happens, it was not we who came up with the idea of ​​using ash to produce building materials, but the practical West - ash and slag materials have long been widely used there in construction and housing and communal services. Main value new method of manufacturing building materials from ash - nature conservation.

Rejoice, environmentalists and Greenpeace: the danger of environmental disasters associated with the danger of erosion of ash dumps and pollution of the environment by ash is reduced to a minimum. There is a huge cost savings - after all, a lot of money is spent on the maintenance of ash storage facilities. The rest of the advantages of ash recycling lies in the economic benefits of using this recyclable material.

A brick created from ash is suitable for building a residential building, a production facility, and a fence. It can even be used as a facing. The recipe for making such a brick is extremely simple: 5% water, 10% lime, the rest is ash (salt and pepper to taste).

The modern price of such a brick, produced, for example, at the Omsk plant (SibEK LLC - Siberian efficient brick) is 5–6 rubles, which makes this “product” very competitive.

Brick tests prove its high quality and wide application possibilities. Strength, water absorption, frost resistance are not inferior to silicate brick. The thermal conductivity index is close to that of wood. Yes, and the appearance pleases with its almost perfect shape - the dimensional tolerances of such a brick are not more than 0.5 millimeters, and this, if you think about it, is again savings - this time on the amount of setting mortar. In addition, ash brick is lighter, more convenient in masonry, and allows you to make it flawlessly even. For improvement appearance bricks, dyes can be added to its composition.

Life pushes to search for new ideas and solutions. The use of ash as a raw material for bricks and other building materials is a truly successful and very timely discovery. The number of “killed hares” in this case is much more than the notorious two. And once again the proverb is confirmed that everything of value is under our feet.

Everyone knows that one of the most versatile and ancient fertilizers is wood ash. It not only fertilizes and alkalizes the soil, but creates favorable conditions for the vital activity of soil microorganisms, especially nitrogen-fixing bacteria. It also increases the vitality of plants. It has the most favorable effect on the crop and its quality than industrial potash fertilizers, since it contains almost no chlorine.

The Technoservice company was able to organize the production of deep utilization of bark and wood waste, and, as a result, received an environmentally friendly complex fertilizer of prolonged action - granulated wood ash (DZG).

The main advantages of DZG:

• Attractive Feature this product is its new granular format. The size of the granules is from 2 to 4 mm, it is convenient for packaging and transportation, it is easy to transport it by any means of transport in containers or bags, it is convenient to apply it to the soil by any type of equipment. The granular format contributes to more favorable working conditions for the staff.
• Processing and application of dusty ash is a very complex process. To reduce the level of dusting when applying agricultural fertilizers, it is more efficient to use granular ash. Granulation facilitates the process of applying ash, and also slows down the process of ash dissolution in the soil. Slow solubility is an advantage, as agricultural land is not subjected to shocks associated with changes in acidity and nutrient medium.
• Application wood ash granulated - maximum effective way combating the process of soil acidification. In addition, the soil structure is restored - it becomes loose.
• Wood ash granulated contains everything, with the exception of nitrogen, the nutrients necessary for plants. DZG practically does not contain chlorine, so it is good to use it for plants that react negatively to this chemical element.
• Wood ash granulated is stored and indefinitely stored in standard dry warehouses for storage of mineral fertilizers at natural humidity and air ventilation.

Land investment

Ash fertilizers from Technoservice are the best investment in your land. Wood ash granulated is an efficient, environmentally friendly and income-generating element of a responsible farmer.

By introducing DZG, you guarantee an increase in the value of your lands and their safety for future generations. Thus, you can profitably use your soil as an object of long-term investment. Thanks to a good choice of object, even non-profitable land will turn into a fully cropped part of the farm property. natural proportions nutrients, long duration of exposure, slow solubility and uniform distribution make DZG Technoservice LLC an excellent solution for both Agriculture as well as from an environmental point of view!

DZG - to increase productivity!

During field research, in accordance with the Leningrad region program conducted in 2008-2011. on acid soddy-podzolic soil, withdrawn from agricultural use about 5 years earlier, it was possible to draw the following conclusions:

• Wood ash from boiler houses is suitable for increasing fertility and eliminating the high acidity of soddy-podzolic soils.
• A total increase in crop yields of 25-64% over 3 years of crop rotation was obtained due to only one measure: liming of slightly acidic soddy-podzolic soil with wood ash from boiler houses.
• With complex tillage, together with mineral and organic fertilizers, significantly larger yields can be achieved.
• It is recommended to use wood ash from boiler houses as a chemical ameliorant during periodic and maintenance liming of acidic soddy-podzolic soils.

According to the All-Russian Research Institute of Agrochemistry D.N. Pryanishnikov DZG can be used as mineral fertilizer with the properties of an ameliorant for the main application for agricultural crops and ornamental plantings on acidic and slightly acidic soils in open and protected ground.

Approximate norms and terms of application in agricultural production:

• all crops - the main or pre-sowing application at the rate of 1.0-2.0 t/ha;
• all crops - the main application (as an ameliorant to reduce soil acidity) at the rate of 7.0-15.0 t/ha with a frequency of 1 time in 5 years.

Approximate doses, terms and methods of applying an agrochemical in personal subsidiary plots:

• vegetable, flower-decorative, fruit and berry crops - application during tillage in autumn or spring or during sowing (planting) at the rate of 100-200 g/m2;
• vegetable, flower-decorative, fruit and berry crops - application during tillage in autumn or spring (as an ameliorant to reduce soil acidity) at the rate of 0.7-1.5 kg / m2 with a frequency of 1 time in 5 years.

G.Khabarovsk



In the process of activity of electric power enterprises, a lot of ash and slag waste. The annual flow of ash to ash dumps in Primorsky Krai is from 2.5 to 3.0 million tons per year, Khabarovsk - up to 1.0 million tons (Fig. 1). Only within the city of Khabarovsk, more than 16 million tons of ash are stored in ash dumps.

Ash and slag waste (ASW) can be used in the production of various concretes, mortars. Ceramics, thermal waterproofing materials, road construction, where they can be used instead of sand and cement. Dry fly ash from electrostatic precipitators of CHPP-3 finds greater application. But the use of such wastes for economic purposes is still limited, including due to their toxicity. They accumulate a significant amount of dangerous elements. Dumps constantly generate dust, mobile forms of elements are actively washed out by precipitation, polluting the air, water and soil. The use of such waste is one of the most urgent problems. This is possible by removing or extracting harmful and valuable components from the ash and using the remaining mass of ash in the construction industry and the production of fertilizers.

Brief description of ash and slag waste

At the surveyed thermal power plants, coal is burned at a temperature of 1100-1600 C. During the combustion of the organic part of the coal, volatile compounds are formed in the form of smoke and steam, and the non-combustible mineral part of the fuel is released in the form of solid focal residues, forming a dusty mass (ash), as well as lumpy slags. The amount of solid residues for hard and brown coal ranges from 15 to 40%. Coal is crushed before burning and, for better combustion, a small (0.1-2%) amount of fuel oil is often added to it.
During the combustion of crushed fuel, small and light particles of ash are carried away by flue gases, and they are called fly ash. The particle size of fly ash ranges from 3-5 to 100-150 microns. The amount of larger particles usually does not exceed 10-15%. Fly ash is captured by ash collectors. At CHPP-1 of Khabarovsk and Birobidzhanskaya CHPP, ash collection is wet on scrubbers with Venturi pipes, at CHPP-3 and CHPP-2 of Vladivostok, it is dry on electrostatic precipitators.
Heavier ash particles settle on the fireboxes and are fused into lumpy slags, which are aggregated and fused ash particles ranging in size from 0.15 to 30 mm. Slags are crushed and removed with water. Fly ash and crushed slag are first removed separately, then mixed, forming an ash and slag mixture.
In the composition of the ash and slag mixture, in addition to ash and slag, particles of unburned fuel (underburnt) are constantly present, the amount of which is 10-25%. The amount of fly ash, depending on the type of boilers, type of fuel and the mode of its combustion, can be 70-85% by weight of the mixture, slag 10-20%. Ash and slag pulp is removed to the ash dump through pipelines.
Ash and slag during hydrotransport and at the ash dump interact with water and carbon dioxide. They undergo processes similar to diagenesis and lithification. They quickly succumb to weathering and when drained at a wind speed of 3 m / s, they begin to dust. The color of the ASW is dark gray, layered in the section, due to the alternation of uneven-grained layers, as well as the deposition of a white foam consisting of aluminosilicate hollow microspheres.
The average chemical composition of the ASW of the surveyed CHPPs is given in the following table 1.

Table 1

Limits of the average content of the main components of ASW

Ash from CHP plants using coal, in comparison with the ashes of thermal power plants using brown coal, they are characterized by an increased content of SO3 and p.p.p., and a reduced content of oxides of silicon, titanium, iron, magnesium, and sodium. Slags - with a high content of oxides of silicon, iron, magnesium, sodium and reduced oxides of sulfur, phosphorus, p.p.p. In general, the ashes are high-silica, with a fairly high content of aluminates.
The content of impurity elements in ASW according to spectral semi-quantitative analysis of ordinary and group samples is shown in Table 2. Gold and platinum represent industrial value, according to the reference book, Yb and Li approach this in maximum values. The content of harmful and toxic elements does not exceed the permissible values, although the maximum contents of Mn, Ni, V, Cr are approaching the "threshold" of toxicity.

table 2

ASW consists of crystalline, vitreous and organic components.

The crystalline substance is represented both by primary minerals of the mineral substance of the fuel, and by new formations obtained in the process of combustion and during hydration and weathering in the ash dump. In total, up to 150 minerals are found in the crystalline component of ASW. The predominant minerals are meta- and orthosilicates, as well as aluminates, ferrites, aluminoferrites, spinels, dendritic clay minerals, oxides: quartz, tridymite, cristobalite, corundum, -alumina, oxides of calcium, magnesium and others. Often noted, but in small quantities, ore minerals - cassiterite, wolframite, stanin and others; sulfides - pyrite, pyrrhotite, arsenopyrite and others; sulfates, chlorides, very rarely fluorides. As a result of hydrochemical processes and weathering, secondary minerals appear in ash dumps - calcite, portlandite, iron hydroxides, zeolites and others. Of great interest are native elements and intermetallics, among which are found: lead, silver, gold, platinum, aluminum, copper, mercury, iron, nickel iron, chromium ferrides, cuprous gold, various alloys of copper, nickel, chromium with silicon and others.

Finding drop-liquid mercury, despite high temperature combustion of coal is a fairly common occurrence, especially in the composition of the heavy fraction of enrichment products. This probably explains the mercury contamination of soils when ASW is used as a fertilizer without special treatment.

Vitreous substance - a product of incomplete transformations during combustion, constitutes a significant part of evils. It is represented by differently colored, mostly black glass with a metallic luster, various spherical vitreous, mother-of-pearl microspheres (balls) and their aggregates. They form the bulk of the slag component of ASW. In composition, these are oxides of aluminum, potassium, sodium and, to a lesser extent, calcium. They also include some heat treatment products. clay minerals. Often the microspheres are hollow inside and form foamy formations on the surface of the ash dump and catchment ponds.

Organic matter is represented by unburned fuel particles (under-burning). The organic matter transformed in the furnace is very different from the original and is in the form of coke and semi-coke with very low hygroscopicity and volatile yield. The amount of underburning in the studied ASW was 10-15%.

Valuable and useful components of ASW

Of the ASW components, iron-containing magnetic concentrate, secondary coal, aluminosilicate hollow microspheres and an inert mass of aluminosilicate composition, a heavy fraction containing an admixture of noble metals, rare and trace elements, are of practical interest in the ash.

As a result of many years of research, positive results have been obtained in the extraction of valuable components from ash and slag waste (ASW) and their complete utilization (Fig. 2).

By creating a consistent technological chain of various devices and equipment, it is possible to obtain secondary coal, iron-containing magnetic concentrate, heavy mineral fraction and inert mass from ASW.

secondary coal. During the technological study, a coal concentrate was isolated by the flotation method, which we called secondary coal. It consists of particles of unburned coal and its products thermal processing– coke and semi-coke, characterized by increased calorific value (>5600 kcal) and ash content (up to 50-65%). After the addition of fuel oil, secondary coal can be burned at a thermal power plant, or, by making briquettes out of it, sold to the population as fuel. It is extracted from ASW by flotation. Yield up to 10-15% by weight of processed ASW. The size of coal particles is 0-2 mm, less often up to 10 mm.

Iron-containing magnetic concentrate obtained from ash and slag waste consists of 70-95% of spherical magnetic aggregates and scale. Other minerals (pyrrhotite, limonite, hematite, pyroxenes, chlorite, epidote) are present in amounts from single grains to 1-5% by weight of the concentrate. In addition, rare grains of platinoids, as well as iron-chromium-nickel alloys, are sporadically noted in the concentrate.

Outwardly, it is a fine-grained powdery mass of black and dark gray color with a predominant particle size of 0.1-0.5 mm. Particles larger than 1 mm no more than 10-15%.

The content of iron in the concentrate ranges from 50 to 58%. The composition of the magnetic concentrate from ash and slag waste from the CHP-1 ash dump: Fe - 53.34%, Mn - 0.96%, Ti - 0.32%, S - 0.23%, P - 0.16%. According to spectral analysis, the concentrate contains Mn up to 1%, Ni the first tenths of %, Co up to 0.01-0.1%, Ti -0.3-0.4%, V - 0.005-0.01% , Cr - 0.005-0.1 (rarely up to 1%), W - from w. up to 0.1%. The composition is good iron ore with ligating additives.

The output of the magnetic fraction according to the magnetic separation in laboratory conditions ranges from 0.3 to 2-4% by weight of the ash. According to literature data, when processing ash and slag waste by magnetic separation under production conditions, the yield of magnetic concentrate reaches 10-20% by weight of ash, with the extraction of 80-88% Fe2O3 and the iron content of 40-46%.

Magnetic concentrate from ash and slag waste can be used for the production of ferrosilicon, cast iron and steel. It can also serve as a raw material for powder metallurgy.

Aluminosilicate hollow microspheres are a dispersed material composed of hollow microspheres ranging in size from 10 to 500 microns (Fig. 3). The bulk density of the material is 350-500 kg/m3, specific 500-600 kg/m3. The main components of the phase-mineral composition of microspheres are aluminosilicate glass phase, mullite, and quartz. Hematite, feldspar, magnetite, hydromica, calcium oxide are present as an impurity. Their predominant components chemical composition are silicon, aluminum, iron (Table 3). Microimpurities of various components are possible in amounts below the threshold of toxicity or industrial significance. The content of natural radionuclides does not exceed the permissible limits. The maximum specific effective activity is 350-450 Vk / kg and corresponds to building materials of the second class (up to 740 Vk / kg).

SiO2

52-58

Na2O

0,1-0,3

TiO2

0,6-1,0

K2O

Al2O3

SO 3

no more than 0.3

Fe2O3

3,5-4,5

P2O5

0,2-0,3

Humidity

No more than 10

buoyancy

At least 90

The content of Ni, Co, V, Cr, Cu, Zn is not more than 0.05% of each element
Due to their regular spherical shape and low density, microspheres have the properties of an excellent filler in a wide variety of products. Promising areas of industrial use of aluminosilicate microspheres are the production of spheroplastics, road-marking thermoplastics, grouting and drilling fluids, heat-insulating radio-transparent and lightweight building ceramics, heat-insulating unfired materials and heat-resistant concretes.
Abroad, microspheres are widely used in various industries. In our country, the use of hollow microspheres is extremely limited and they, together with the ash, are dumped into ash dumps. For thermal power plants, microspheres are a "harmful material" that clogs the pipes of circulating water supply. Because of this, it is necessary to completely replace pipes in 3-4 years or carry out complex and expensive work to clean them.
The inert mass of the aluminosilicate composition, which is 60-70% of the mass of ASW, is obtained after the removal (extraction) from the ash of all the above concentrates and useful components and heavy fraction. In composition, it is close to the general composition of ash, but it will contain an order of magnitude less glands, as well as harmful and toxic. Its composition is mainly aluminosilicate. Unlike ash, it will have a finer uniform granulometric composition (due to grinding when extracting the heavy fraction). According to ecological and physico-chemical properties, it can be widely used in the production of building materials, construction and as a fertilizer - a substitute for lime flour (ameliorant).
The coals burned at the thermal power plant, being natural sorbents, contain impurities of many valuable elements (Table 2), including rare earths and precious metals. When burned, their content in the ash increases by 5-6 times and may be of industrial interest.
The heavy fraction recovered by gravity using advanced concentration plants contains heavy metals, including precious metals. By fine-tuning, precious metals are extracted from the heavy fraction and, as they accumulate, other valuable components (Cu, rare, etc.). The output of gold from individual studied ash dumps is 200-600 mg per ton of ASW. Gold is thin, non-recoverable by conventional methods. Know-how technology is used to extract it.
Many people are involved in the disposal of ASW. More than 300 technologies for their processing and use are known, but they are mostly devoted to the use of ash in construction and the production of building materials, without affecting the extraction of both toxic and harmful components, and useful and valuable ones.
We have developed and tested in laboratory and semi-industrial conditions a basic scheme for the processing of ASW and their complete disposal (Fig.).
When processing 100 thousand tons of ASW, you can get:
- secondary coal - 10-12 thousand tons;
- iron ore concentrate - 1.5-2 thousand tons;
- gold - 20-60 kg;
- building material (inert mass) - 60-80 thousand tons.
In Vladivostok and Novosibirsk, ASW processing technologies similar in type have been developed, possible costs have been calculated, and the necessary equipment has been provided.
The extraction of useful components and the complete utilization of ash and slag waste through the use of their useful properties and the production of building materials will free up the occupied space and reduce the negative impact on the environment. Profit is desirable, but not the decisive factor. The costs of processing technogenic raw materials with the production of products and simultaneous neutralization of waste may be higher than the cost of products, but the loss in this case should not exceed the costs of reducing the negative impact of waste on the environment. And for energy enterprises, the utilization of ash and slag waste is a reduction in technological costs for the main production.

Literature

1. Bakulin Yu.I., Cherepanov A.A. Gold and platinum in ash and slag waste from the CHPP of Khabarovsk // Ores and Metals, 2002, No. 3, pp. 60-67.
2. Borisenko L.F., Delitsyn L.M., Vlasov A.S. Prospects for the use of ash from coal-fired thermal power plants./JSC "Geoinformmark", M.: 2001, 68p.
3. Kizilshtein L.Ya., Dubov I.V., Spitsgauz A.P., Parada S.G. Components of ashes and slags from thermal power plants. Moscow: Energoatomizdat, 1995, 176 p.
4. Components of ashes and slags from thermal power plants. Moscow: Energoatomizdat, 1995, 249 p.
5. Composition and properties of ash and slag from thermal power plants. Reference manual, ed. Melentyeva V.A., L.: Energoatomizdat, 1985, 185 p.
6. Tselykovsky Yu.K. Some problems of using ash and slag waste from thermal power plants in Russia. Power engineer. 1998, No. 7, pp. 29-34.
7. Tselykovsky Yu.K. Experience in the industrial use of ash and slag waste from thermal power plants // New in the Russian energy sector. Energoizdat, 2000, No. 2, pp. 22-31.
8. Valuable and toxic elements in commercial coals of Russia: Handbook. M.: Nedra, 1996, 238 p.
9. Cherepanov A.A. Ash and slag materials// The main problems of studying and extracting mineral raw materials of the Far Eastern economic region. The mineral resource complex of the FER at the turn of the century. Section 2.4.5. Khabarovsk: Publishing House of DVIM-Sa, 1999, pp. 128-120.
10. Cherepanov A.A. Noble metals in ash and slag waste from Far Eastern thermal power plants // Pacific Geology, 2008. V. 27, No. 2, pp. 16-28.

List of drawings
to the article by A.A.Cherepanov
The use of ash and slag waste from thermal power plants in construction

Fig.1. Filling the ash dump of CHPP-1, Khabarovsk
Fig.2. circuit diagram integrated processing of ash and slag waste from thermal power plants.
Fig.3. Aluminosilicate hollow microspheres ASW.