SU734162A1 - Method of producing light filter - Google Patents

Description

The invention relates to the field of building materials, namely the production of artificial lightweight aggregates for concrete, c. Particularly to the method of producing expanded gravel from the ashes of thermal power plants (TPP). For wet ash gravels, fly ash accumulated in ash deposits containing unburned coal, an average of 10-15%, is used, which prevents sintering and swelling during firing. Exhausted ash gravel with a low bulk density and durable can be obtained by roasting free raw materials containing less than 3% coal. For this, the feedstock is pretreated to reduce the carbon content. There is a known method for producing an expanded ash ash gravel with more than 3% residual coal soda ash by crushing ash by crushing, removing the coal by flotation, and then dehydrating the ash to a residual moisture content of 15g-20% and granulating, drying the granules at 115a-1180 by drying and drying the granules at 115a-1180 C. The lack of a method is its multi-stage, high energy consumption, which limits its limited use. A known method of making ash gravel, including granulation, baking, preliminary heat treatment of granulated raw materials in a rotary kiln, at 5OO-1OOO C, cooling the granules, their subsequent grinding, re-granulating, burning the obtained granules at 115О-130О С in another rotary kiln and cooling the final Shedubaus The disadvantage of this method is the duration of the procession for the production of ash gravel from ash with an increased Heerqp content of coal. Thus, the laboratory tests of the method showed that the duration of the preliminary heat treatment, even at a maximum temperature of 10 ° C, for shining the coal content from 10-15% to 3% or less, is NO min. Such a long preliminary heat treatment leads to mechanical abrasion and deterioration to the dust in the foot of the state. In addition, the pre-heat treatment temperature (up to 10OO C) is insufficient for contact sintering of ash particles, since the initial melting point of the ash is not less than 11OO C, which also leads to the destruction of the granules to a dust-like state. Another disadvantage of this method is the increased energy consumption associated with the use of two rotary kilns: for preliminary heat treatment and for firing, as well as for intermediate cooling operations of thermally prepared granules, their grinding, re-granulation and reheating of the granules to the firing temperature. The closest in technical terms and effect to the present invention is a method of making a lightweight Solder from an ash with an increased content (up to 19%) of unburned coal by heat treatment of sphamy granules in a solid heat transfer medium, at a temperature with 6 times the upper limit of the interval of elongation. 12OO ° C and cooling Z. Roasting in the medium of a solid heat carrier at these temperatures requires prolonged isothermal exposure for heating. So, when using ash with a residual coal content of 18%, its content in granules for 15 minutes of roasting decreases only to the level of 14%. Therefore, this firing mode is not. ensures that coal is ignited to the maximum permissible content - less than 3%. Bulk bulk filler mass ranges from 5OO to 8OO kg / m. The purpose of the invention is to intensify the process of burning coal and reducing the bulk weight of the filler J. This is achieved by the fact that in the method of making a lightweight aggregate from ashes with a high content of unburned coal by heat treatment, granules of solid matter are formed in a medium of solid carbon and cooled. They are heated by heating them at a rate of 65O-7Op C min to 135O, holding at this temperature for 15-16 minutes and then lowering the temperature to 1150-1180 ° C with a velocity of 14-17 C / min. The method is carried out as follows. Molded granules from multi-ash ash with an unburned coal content of 10–15% are fed into a rotating continuous-flow furnace in a pre-heat treatment zone together with a solid heat carrier, for example, with a coarse quartz sand in a 1: O ratio, 25 by weight. In the pre-heat treatment zone, the granules are exposed to a gas stream with a temperature of 1450-1500 ° C, while the granules are heated at a speed of 650-70 ° C / min from up to 135 ° -1400 ° C. At a temperature of 1350-1400 ° C, the temperature of the beginning of the ash melting, at least 1100 ° C, contact sintering of ash particles occurs first on the surface of the granules with the formation of a caked, decarbon-free, finely-coated shell, kotfa prevents mechanical abrasion and destruction of the granules during peresysheniya and translational movement in a rotary kiln. At a temperature of 135 ° -40 ° C, the granules are held in an oven for 15-16 minutes. During the time of isothermal exposure, intrinsic coal burnout from the loose core of the granules occurs. The solid heat carrier improves heat exchange, promotes coal burning, prevents contact sintering of the pellets with each other and, slowing down the advance along the furnace, provides the necessary time for preliminary heat treatment and subsequent roasting. After the combustion of coal, the content of 1–3% ash granules softens, acquires a pyroplastic state, and then enters the burning zone, in which it is sintered and expanded. Calcination is carried out with a decrease in temperature from 1350-14OO to 115 ° 118 ° C at a rate of 14-17 C / min. At the end of the puffing process, the granules are separated from the solid coolant and are fed for cooling. In the case of primary additives, it is possible to recycle the ashes of thermal power plants with coal content in the ash up to 2–30% using the proposed method. 11 p and meer. For carrying out the method of making ash gravel, a rotary kiln is used, equipped with a combi rc Christmas tree device. The burner includes short-flame peri-peripheral burners (28 pieces) and a central long-flare burner of the type GVP. The loading of the granulated material and the refractory component (silica sand with a particle size of 0.5-2.0 mm) is carried out in the zone of action of a short torch, where an intense thermal shock is created at a gaseous temperature of .14501500 ° C. The quartz sand, which is heated in the area of thermal shock, later plays thermal process the role of solid heat transfer and together with the granules enters; isothermal burnout zone The TeMnepiaTypa of the material in this gune is maintained at 13-50-1400 ° C using a long torch of the central burner. An increase in the temperature of the material is also provided by the exothermic process of burning out coal particles. The relative rate of advance of quartz sand along the furnace is 3-4 times less than the granules, therefore, accumulating to the volume of the calcined material, quartz sand sharply slows down the forward movement of the granules along the furnace, which at elevated temperatures ensures the most complete flow of physical and chemical particles. processes of oxidation of coal particles, followed by the porisation of a silicate melt.

Temperature measurement from the furnace loading and unloading was carried out. a platinum-plug-in thermocouple thermometer; and, over the length of the furnace, an optical radiation instrument OPRIR-O173

Material heating rate

in the zone of thermal shock, C / min. Duration of isothermal holding in the zone of burning coal, min

The temperature of the material in the burning zone,

Duration of stay in the zone of swelling, min

The temperature gradient of the temperature drop of the material in the swelling zone on. the interval 1350-1180 S / m

40

Claims (1)

Formula invented and- A method of making a lightweight ash aggregate with a high content of unburned coal by heat treatment of the formed granules in a solid heat transfer medium and cooling, characterized in that, in order to intensify the process of burning coal and reducing the bulk bulk of the aggregate, the granules are heated by heating them at a speed of 650 -700 C / min to a temperature of 13 50-1400 ° С, holding at this temperature for 15-16 minutes. and the subsequent decrease in temperature to 1150-1180 C at a speed of 14 17 C / mn. Comparative qualitative demonstration of the filler obtained by the known method and the proposed content in the zone of unburned fragile,% 13.5 Characteristics of the finished product of the spiny gravel factory, in Dzerzhinsk, pr. Bulk bulk density, kg / m 700-800 450-500 strength at squeezing in the cylinder, kgf / cm 42-56 22-34 residual content, coal,% 7-80.3-0.6 gravel structure is dense Furnace productivity by ash grace, 2, O-2.5 4.5-5, 0 Modes of firing in the environment of hard-water heating medium 1050-1100 С 77341628 Sources of information, 2, Avts bracket- USSR certificate taken into account in the examination number 896734, cl. C 04 B 31 / 2O, 1971. 1, Copyright certificate of the USSR on porous aggregates №514794, cl. С О4 In 31/20, S layer coolant, sat. Labor 1976.1973, no. 27/55, p. 82-в7. 3 „Przhetslsky V. A. and ar. Get