RU2692334C1 - Method of extracting unburned carbon from tpp fly ash - Google Patents

Abstract

FIELD: waste processing and disposal.SUBSTANCE: invention relates to processing of wastes from thermal power plants, in particular to a method of recovering unburned carbon from thermal power plant fly ash to obtain an aluminosilicate product. Method of recovering unburned carbon from thermal power plant fly ash involves formation of an aqueous suspension of fly ash, adding to the collector and foaming agent suspension, mixing the suspension with reagents and hydrophobization of unburned carbon to form a foam layer in order to lift unburned carbon. In an aqueous suspension of fly ash at ratio of ash: water 1:2–1:4, a collector is added in the form of a mixture of thermal cracking gas oil with kerosene, preferably in ratio of 1:1 in amount of 5–8 kg per ton of ash. Suspension and header are mixed for 1–5 minutes. Afterwards foaming agent is added to obtained mixture in form of pine oil in amount of 0.2–0.3 kg per ton of ash, mixed for 0.5–1 minutes, after which mixture of suspension with reagents is flotated for 5–10 minutes to form foam layer and tailings of main flotation with subsequent extraction and obtaining of target products in form of carbon, suitable for combustion at TPP, and aluminosilicate product for use in production of construction materials. Foam product of the main flotation is subjected to operation of cleaning flotation in the second flotation cell to produce a second concentrate of foam product and chamber industrial product.EFFECT: considerable reduction of consumption of expensive reagents used during implementation of the method and simplification of process equipment of flotation process for obtaining of target products in form of higher-quality carbon concentrate and aluminosilicate product under condition of complete use of flue ash of TPP.1 cl, 4 ex

Description

The invention relates to the processing of waste thermal power plants, in particular, to a method for separating unburned carbon from fly ash from thermal power plants to produce an aluminosilicate product.

A pilot plant is known that implements a method for separating unburned coal from fly ash from a thermal power plant generated by burning Donetsk anthracites (Kieselstein L.Ya., Dubov I.V., Shpittsgluz A.L., Parada S.G. Slag Thermal Power Plant ", Moscow: Energoatomizdat, 1995, pp. 147-152).

The known installation includes a unit for thickening the ash suspension in hydrocyclones, a unit for preparing the slurry for flotation, including reagent dispensers (collector and blowing agent), a contact tank for mixing the slurry with reagents, flotation machines for primary and cleaner flotation, a dewatering unit for flotation concentrate on disk vacuum filters. The disadvantage implemented in the installation method are relatively large losses of carbon with small fractions going into the discharge of hydrocyclones, which prevents their subsequent use, for example, as additives to the cement due to the increased amount of unburned carbon.

There is a method of separation of coal-containing product, including hydroclassification and flotation, and hydroclassification of coal-containing product is carried out on the boundary class of 0.25 mm in slag and ash ash, while the slag is sent to grinding for cement production, and ash ash before flotation is divided into boundary class 0, 05 mm for two fractions, each of the fractions separately conditioned with a collector and blowing agent, flotation is carried out using a column apparatus, and flotation of a large class of more than 0.05 mm is carried out in The flow-through section of the column apparatus, flotation of a small class less than 0.05 mm is carried out in the counter-current section of the column apparatus, the resulting combined flotation concentrate of the two sections is dewatered and sent for combustion as fuel, and the waste of each of the flotation sections is dehydrated separately and used in the production of cement (see RF Patent No. 2438791, published January 10, 2012).

The disadvantage of this method of separation (or separation) of a coal-containing product is the complication of the technological scheme (separate flotation of large and fine ash classes), which does not guarantee the constancy of the load of flotation chambers by the amount of solid and unburned carbon particles in it due to fluctuations of these parameters in the incoming ash .

There is a method of selection of unburned fuel from the ash of thermal power plants, according to which for the preparation of suspensions take 100 wt. parts of ash and 80-110 wt. parts of water, 0.05-0.1 wt. including phosphate dibasic ammonium and 0.05-0.1 wt. including tetraborate sodium, while the separation of the suspension is carried out by vibration or flotation or vibration, followed by flotation (see RF patent №1176952, published. 07.09.1985).

The disadvantages of this method are the complexity and high cost of the process of separating unburned fuel from TPP ash caused by the use of vibrational separation methods that are additional to flotation, the use of relatively expensive flotation reagents with a relatively low component separation efficiency.

The closest in technical essence and the achieved result to the proposed method is the removal (or separation) of unburned carbon from the fly ash of thermal power plants, including the formation of an aqueous suspension of fly ash, adding to the suspension a collector in the form of kerosene and a frother in the form of methyl isobutylcarbinol (MIBK), mixing suspensions with reagents in a multi-chamber immersion mixer and hydrophobization of unburned carbon to form a foam layer in order to lift said unburned carbon (see RF Patent No. 2343984, January 20, 2009 - prototype).

The coal concentrate obtained in this way can be used as a fuel, and a chamber product containing not more than 1% carbon in the production of lightweight aggregates, as an additive to cement, etc.

The disadvantage of this method is the use of expensive reagent - foaming agent MIBK and relatively high consumption of the collector (collector) in the form of kerosene. For example, when the carbon content in the ash is 5%, the kerosene consumption for flotation was 15% of the carbon content or 7.5 kg per ton of ash.

The basis of the proposed invention is to improve the efficiency of flotation removal of unburned carbon from fly ash of thermal power plants with the production of commercial products - fuel for power plants and aluminosilicate product for use as additives to cement, building materials, etc.

The expected technical result is a significant reduction in the consumption of expensive reagents used in the implementation of the method and simplification of the technological equipment of the flotation process to obtain the target products in the form of higher-quality carbon concentrate and aluminosilicate product subject to the full use of TPP ash.

The technical result is achieved by the fact that in the process of separating unburned carbon from fly ash of a thermal power plant, including the formation of an aqueous suspension of fly ash, adding a collector and a foaming agent to the suspension, mixing the suspension with reagents and hydrophobizing unburned carbon to form a foam layer to lift unburned carbon, According to the invention, a collector in the form of a mixture of thermo-gasoil and kerosene is added to an aqueous suspension of fly ash at the ratio of ash-water 1: 2-1: 4, mainly in the ratio 1: 1 in quantity Twine 5-8 kg per ton of ash, then the suspension and the collector are mixed for 1-5 minutes, after which a frother in the form of pine oil is added in the amount of 0.2-0.3 kg per ton of ash, mixed for 0.5-1 min, after which the mixture of suspension with reagents is subjected to flotation for 5-10 minutes to form a foam layer and tailings of the main flotation, followed by separation and obtaining the desired products in the form of carbon suitable for combustion at TPP, and aluminosilicate product for use in construction x materials.

In addition, the mainstream flotation foam product may be subjected to a clean-up flotation operation in the second flotation cell to produce a second foamy product concentrate and chamber middling.

The specified ranges of the numerical values of the modes of the method of separation of unburned carbon from fly ash of thermal power plants in terms of the ratio of ash-water 1: 2-1: 4, thermogas oil with kerosene 1: 1, pine oil in the amount of 0.2-0.3 kg per ton of ash , the times of mixing and flotation are optimal for achieving a technical result and found as a result of numerous experimental studies to determine the modes of implementation of the proposed method for separating carbon concentrate and aluminosilicate product from TPP ablation ash.

As a result of experimental studies carried out at the JIHT RAS, a relatively simple technological scheme was developed for implementing a method for separating unburned carbon from TPP ablation ash, which does not require preliminary desliming or separation of ablation ash into fraction fractions with subsequent conditioning with reagents and subsequent flotation under various hydrodynamic conditions. At the same time, such modes of implementation of the method were used, which allow, in comparison with the known technical solutions, to more fully use in the power industry and industry the fly ash of thermal power plants, including through the use of more efficient collector and frother.

In the proposed method of removing unburned carbon from fly ash from thermal power plants, first implemented regimes are specifically used, using a mixture of kerosene and thermogas oil as a collector (collector), and pine oil in relatively small quantities as a frother. Kerosene is a refined product consisting of almost 100% of the components boiling away in the temperature range of 180-250 ° C and possessing high flotation activity. Heavy vacuum gas oil catalytic cracking, the content of middle distillate fractions which does not exceed 10%, contains about 70% of aromatic hydrocarbons, half of which are polycyclic compounds having a structure identical to the structures of graphitized carbon ash. Such a composition of thermogas oil provides a high degree of hydrophobization of underburning particles. The content of resinous substances in pine oil to 6% gives the reagent effective foaming properties and provides a reduction in foaming agent consumption. On the other hand, kerosene reduces the viscosity of thermo-gas oil, thereby providing the formation of thin emulsions of the collecting mixture, which have higher flotation activity with less consumption of the collector.

According to the proposed technical solution, the release of unburned carbon from fly ash from a power plant includes the formation of an aqueous suspension of fly ash, for example, in a 1: 3 ratio. After that, a collector and a foaming agent are added to the suspension with alternate mixing of the suspension with reagents and hydrophobization of unburned carbon. Mixing the suspension with reagents and hydrophobicizing carbon is carried out in a flotation machine to form a foam layer in order to lift and separate unburned carbon and separate flotation tailings for the subsequent production of target products.

Below are the results of the practical implementation of the method of separation of unburned carbon from fly ash of thermal power plants in a number of examples confirming the achievement of the specified technical result.

EXAMPLE 1. A sample of ash weighing 500 grams and a particle size of less than 300 microns, containing 9.9% carbon, was mixed with 1.5 liters of water with a ash-water ratio of 1: 3. Then, a mixture of thermo-gasoil and kerosene was added to the suspension at a 1: 1 ratio in the amount of 7.8 kg per 1 ton of ash and stirred without air supply for 1 minute. Then, pine oil in the amount of 300 g per 1 ton of ash was fed into the suspension and the suspension was stirred for 0.5 min. The suspension treated in this way was fed into a 1.7 liter flotation cell, turned on the air and floated the carbon from the ash for 5 minutes. The froth flotation product (main flotation concentrate) and chamber product (main flotation tails) were removed from the chamber. The frothy product was then subjected to a clean-up operation for 5 minutes while supplying air to the second flotation cell. Received the second foam product (finished concentrate) and chamber product cleaner cell flotation (middling).

The finished concentrate and aluminosilicate product, consisting of the tailings of the main flotation and the cleaning product, were filtered, dried, weighed, determining their quantity and, thus, the yield from the original ash sample. Then they determined the carbon content. From these data, calculated the results of the experiment - the product yield, the carbon content in it and the extraction of carbon in this product. When the yield of the finished concentrate was 9.8%, its carbon content was 67.5%, and carbon recovery was 67.0%. The aluminosilicate product had a yield of 91.2% with a carbon content of 3.7%.

EXAMPLE 2. A sample of ash weighing 500 g with a particle size of less than 300 microns, containing 11.0% of carbon, was mixed with 1.5 liters of water. Then, a mixture of thermogas oil and kerosene was added to the suspension as a collector at a ratio of 1: 1 in the amount of 6 kg per 1 ton of ash, followed by stirring for 2 minutes. After that, pine oil was supplied to the suspension in the amount of 210 g per ton of ash and the suspension was stirred for 0.5 min. The treated suspension was supplied to a 1.7 liter flotation cell, the air was turned on, and the primary carbon flotation from ash was carried out for 6 minutes. Foam product (main flotation concentrate) and chamber product (flotation tailings) were removed from the chamber. The frothy product was then subjected to a clean-up operation for 5 minutes while supplying air to the second flotation cell.

Received the second foam product (finished concentrate) and chamber product cleaner cell flotation (middling). The finished concentrate and the aluminosilicate product, consisting of the tailings of the main flotation and the cleaning product, were filtered, dried, weighed, determining their quantity and output from the initial ash sample. Then they determined the carbon content. From these data, calculated the results of the experiment - the product yield, the carbon content in it and the extraction of carbon in this product. When the yield of the finished concentrate was 14.3%, the carbon content in it was 65.8% and the extraction of carbon was 85.5%. The aluminosilicate product had a yield of 85.7% with a carbon content of 1.9%.

EXAMPLE 3. A sample of ash weighing 500 g and a particle size of less than 300 microns, containing 6.1% carbon, was mixed with 1.5 liters of water. Then, a mixture (1: 1) of kerosene with thermogas oil in the amount of 6.5 kg per 1 ton of ash was added to the suspension and stirred for 1 minute. After that, pine oil was added to the suspension in the amount of 270 g per ton of ash and stirred for 0.5 minutes. The suspension treated in this way was fed into a 1.7 liter flotation cell, turned on the air and floated the carbon from the ash for 5 minutes. Foam product (main flotation concentrate) and chamber product (main flotation tails) were removed from the chamber. The frothy product was then subjected to a clean-up operation for 5 minutes while supplying air to the second flotation cell. Received the second foam product (finished concentrate) and chamber product cleaner cell flotation (middling).

The finished concentrate and aluminosilicate product, consisting of the tailings of the main flotation and the cleaning product, were filtered, dried, weighed, determining their quantity and, thus, the yield from the original ash sample. Then they determined the carbon content. From these data, calculated the results of the experiment - the product yield, the carbon content in it and the extraction of carbon in this product. When the yield of the finished concentrate was 6.3%, the carbon content in it was 63.7%, and carbon recovery was 66.2%. The aluminosilicate product had a yield of 93.7% with a carbon content of 2.2%.

EXAMPLE 4. A sample of ash weighing 500 grams and fineness less than 300 microns, containing 6.25% carbon, was mixed with 1.5 liters of water. Then, a mixture (1: 1) of kerosene and thermogas oil in an amount of 5 kg per 1 ton of ash was added to the suspension as a flotation collector and stirred for 1 minute. Then, pine oil was supplied to the suspension in the amount of 220 g per 1 ton of ash and the suspension was stirred for 0.5 min. The treated suspension was supplied to a 1.7 liter flotation cell, the air was turned on, and the primary carbon flotation was performed for 5 minutes.

Foam product (main flotation concentrate) and chamber product (flotation tailings) were removed from the chamber. The frothy product was then subjected to a clean-up operation for 5 minutes while supplying air to the flotation cell. Received the second foam product (finished concentrate) and chamber product cleaner cell flotation (middling). The finished concentrate and the aluminosilicate product, consisting of the tailings of the main flotation and the cleaning product, were filtered, dried, weighed, determining their quantity and output from the initial ash sample. Then they determined the carbon content. From these data, calculated the results of the experiment - the product yield, the carbon content in it and the extraction of carbon in this product. When the yield of the finished concentrate was 8.2%, the carbon content in it was 61.8%, and the extraction of carbon in it was 81.1%. The aluminosilicate product had a yield of 91.8% with a carbon content of 1.29%.

The advantages of the considered method of separating unburned carbon and aluminosilicate product from TPP ablation ash are the same as the yield of carbon concentrate and carbon extraction in it turned out to be significantly higher than previously achieved, which provides a significant increase in production of additional fuel for TPP from ash. At the same time, the carbon content in aluminosilicate intermediate product is 1.8% lower, which gives it a preference for use as an additional raw material in the production of building materials.

The consumption of frother in the form of pine oil when the mixture of thermogas oil and kerosene was used as a collector turned out to be almost 30% lower compared to pure kerosene, which is explained by the presence of resin acids in thermogas oil that have additional foaming properties. The yield of carbon concentrate turned out to be 1.9% higher in comparison with the known method, and the extraction of carbon — by 15.1%. The aluminosilicate product also has a lower carbon content (by almost 1%), which makes it possible to expand the range of its use, for example, as a substitute for cement in the production of building products.

The results of the above experiments indicate that the efficiency of using the proposed collector (collector) is increased in comparison with the flotation of fly ash from thermal power plants with kerosene and with a low content of underburning (carbon). According to European (German) standards, the carbon content in the ash should not exceed 3-4%, while these experiments allow the flotation of ash with a carbon content of 5% or more. The flow rate of the collective mixture (thermo-gas oil and kerosene) in the proposed method at 6 kg / ton of ash is 23% lower than in experiments using only kerosene as a collector. At the same time, the consumption of pine oil in the proposed method (210 g / t ash) was 36% lower than in the known method (330 g / t ash), which is associated with the content of resinous substances in thermogas oil with high foaming properties.

As a result, the proposed method for separating unburned carbon from fly ash from thermal power plants allows to significantly reduce the consumption of expensive reagents used in the implementation of the method and simplify the technological equipment of the flotation process to obtain the target products in the form of higher-quality carbon concentrate and aluminosilicate product with full use of fly ash from thermal power plants .

Claims (2)

1. The method of separation of unburned carbon from fly ash TPP, including the formation of an aqueous suspension of fly ash, adding to the suspension of the collector and foaming agent, mixing the suspension with reagents and hydrophobization of unburned carbon to form a foam layer to lift unburned carbon, characterized in that water suspension of fly ash at a ratio of ash: water 1: 2-1: 4 add a collector in the form of a mixture of thermogas oil and kerosene, mainly in a ratio of 1: 1 in the amount of 5-8 kg per ton of ash, then stir the suspension Drainage and collector for 1-5 minutes, after which a foaming agent in the form of pine oil is added to the mixture in the amount of 0.2-0.3 kg per ton of ash, mix them for 0.5-1 minutes, after which the suspension mixture with reagents subjected to flotation for 5-10 minutes to form a foam layer and tailings of the main flotation, followed by separation and production of target products in the form of carbon suitable for combustion at thermal power plants, and aluminosilicate product for use in the production of building materials. 2. The method according to p. 1, characterized in that the froth product of the main flotation is subjected to the operation of cleaner cell flotation in the second flotation cell to obtain a second concentrate of the froth product and chamber middling.