RU2302390C2 - Method of production of granulated porous materials - Google Patents

Abstract

FIELD: construction materials industry; methods of production of the granulated porous materials.

SUBSTANCE: the invention is pertaining to production of the granulated porous materials and may be used in the construction materials industry. The technical result of the invention is the improved strength characteristics, the reduced volumetric mass, the decreased adsorption of the water by the granulated porous materials and the wastes utilization. The method of production of the granulated porous materials provides for crushing, weight dosing, milling in the mill, drying of the granules, the foaming of the granules with the separation medium and the annealing. The milling is conducted in the straight-through centrifugal ellipse-shaped mill with humidification of the powder by the water from 0.5 up to 5 % of the mass and with addition of the making foam additive. Then using the classifying screen conduct sifting of the fine hydrated powder with the specific surface of 6000 cm²/g, mixing with the binding plasticizer, granulation by the reinforced feed-screw granulator through the spinning nozzles, at the outlet the granules are cut off by the cutter. Before powdering the granules are subjected to the balling with production the correct spherical shape, powdering, drying in an electric induction furnace at the temperature of 420°C, foaming in the tunnel-screw conveyor type furnace at the temperature of 730-830°C and separation in the wiping drum.

EFFECT: the invention ensures the improved strength characteristics, the reduced volumetric mass and adsorption of the water by the granulated porous materials, utilization of the wastes.

1 dwg, 1 tbl

Description

The invention relates to the production of granular porous materials and can be used in the building materials industry.

A known method of manufacturing granular foam glass, which consists in the joint grinding of glass raw materials and a blowing agent, granulation, during which a binder component is introduced into the mixture, and subsequent heat treatment [Demidovich B.K. Production and use of foam glass. Minsk, 1072, p.196-201].

The disadvantage of this method is the high cost of the finished product.

The closest in technical essence is the method of producing granulated foam glass on a continuously operating technological line, including crushing of cullet, weight dosing and co-grinding of cullet and pore former in mills, granulating the mixture with irrigation with an aqueous solution of soluble glass, drying granules, foaming granules in a rotary gas furnace and cooling of the granules in a rotating drum [RU p. No. 2162825, IPC С03С 11/00, publ. 09/10/2001].

The disadvantages of this method are that the grinding of the glass to the required fineness (5000 cm ² / g) is carried out in ball mills of periodic action for a long time (10-15 hours) with an effort of a certain free fall of the balls (1g). Ball mills cannot provide the necessary mechanical activation of the powder to improve the quality of the final product. Granulation in a plate granulator does not give a uniform density of raw granules, central and concentric voids are formed, which ultimately does not allow to obtain a uniform cellular structure of foamed granules and especially negatively affects their strength. The foaming in a gas rotary kiln, during non-isothermal firing, is significantly affected by the convective component of heat transfer, the heating of the granules proceeds relatively slowly 0.02 · 10 ² - 0.07 · 10 ² ° C / s. Here, the foaming process is a combination of sequential, sequentially parallel chemical reactions, crystallization of solid and liquid phases, which is an exothermic reaction, is built into the sequence of endothermic chemical reactions. Crystallization gets sufficiently favorable conditions for its development, exerting a negative impact on the process of pore formation in granules, making them heavier. Slow cooling of the granules in a long unheated drum does not create optimal conditions for annealing the foam glass.

The technical result of the invention is to increase the strength characteristics, reduce bulk density, reduce heat conductivity, reduce water absorption of granular porous materials and utilize waste.

The technical result is achieved by the fact that in the method for producing granular porous materials, including crushing, weight dosing, grinding in a mill, drying granules, foaming granules with a separating medium and annealing, it is new that grinding is carried out in a continuous flow centrifugal elliptical mill with wetting of the powder water from 0.5 to 5% by weight and the addition of a blowing agent, then screening is carried out on a classifier of fine-ground hydrated powder with a specific surface of 6000 cm ² / g, mixed with a binder layer with an identifier, granulate on a reinforced screw granulator through dies, at the exit the granules are cut with a knife, and before dusting the granules are doused to obtain the correct spherical shape, dusted, dried in an electric induction furnace at 420 ° C, foamed in a tunnel screw conveyor furnace at a temperature of 730 ° -830 ° C and separated in a wiper drum.

The drawing shows a block diagram of a technological line for the production of granular porous materials.

A method of manufacturing granular porous materials is carried out on a production line consisting of a receiving hopper 1, a jaw crusher 2, a hammer crusher 3, a stock hopper for a crusher 4, a plate feeder 5, a water dispenser 6, a centrifugal elliptical mill of passage type 7, a classifier 8, a powder supply hopper 9 , a disk feeder 10, an additive dispenser 11, a pressure tank 12, a turbo-mixer 13, a reinforced screw granulator 14, a disk pelletizer 15, a dusting machine 16, an electric induction furnace ears 17, a stock tank of dried granules 18, an electric tunnel-auger foaming furnace 19, an electric tunnel-conveyor annealing furnace for granules 20, a cleaning drum 21 and a finished product warehouse 22. This processing line uses tape, scraper, and screw conveyors as raw materials and semi-finished products are processed conveyors, bucket elevators and bulk filling devices.

The method is as follows: raw materials: cullet, silicate block, glass granulate, vitrified perlite, zeolite, slag and other natural and technogenic silicate materials (depending on which end product is planned to be obtained) are loaded into a receiving hopper 1, from where it enters the jaw crusher 2 for the destruction of large pieces, from it to a hammer mill 3 to obtain a crusher with a grain size of up to 5 mm, from here the crusher is fed to the stock hopper 4 with a bucket elevator, and then it is fed to a centrifugal electric feeder 5 a type 7 blender mill, in which water is also dispensed by dispenser 6 to moisturize the powder from 0.5 to 5% by mass, and foaming additives, mainly carbon black, 0.2-0.3% by mass, are also fed by additive dispenser 11. Here, due to the high-stress process, fine grinding, mechanical activation and hydration of the powder occur in a relatively short time, which allows to reduce the foaming temperature by 90 ° C and, in combination with dense granulation, to obtain a uniform porous honeycomb structure of the foam material and reduce the bulk density of granules on average 1.5 times in comparison with the unhydrated mixture. After screening in classifier 8, finely ground hydrated powder with a specific surface of 6000 cm ² / g is conveyed by a belt conveyor (or bucket elevator) to the powder storage hopper 9, from which a plate feeder 10 is fed into a turbopaste mixer 13, into which a binder is fed from a pressure tank 12 - plasticizer (liquid glass solution with a density of 1.12 g / cm ³ ), and the moistened charge enters the reinforced screw granulator 14. In the screw granulator, the mixture is pressed through the dies, and at the exit the granules are cut with a knife, changing the filter granules, you can change the size of the granules, while they are more dense and uniform in structure than when obtained by simple rolling from a powder, which positively affects the quality of the final product, then the granules flow through the trench into a disk pelletizer 15, in which they acquire the correct spherical shape, the obtained raw granules are conveyed through the belt conveyor to the dusting machine 16, where the granules are dusted (for example, with alumina or building lime), which prevents the granules from sticking together in the furnace drying, and sintered lime with ganula positively affects the adhesion of the granular porous material with cement stone, then the granules enter the electric drying induction furnace 17, where the raw granules are uniformly dried at a temperature of 420 ° C, with a minimum humidity of 1-2% at the outlet . The dried granules by a bucket elevator are fed into the stockpot of dried granules 18, and then from the hopper 18 they are fed by a belt feeder to an electric tunnel-auger foaming (pore-forming) furnace 19, where the granules are moved by screws located transverse to the flow direction. There is no convective component of heat transfer in this furnace; granules are isothermally heated to a temperature of 730 ° -830 ° C due mainly to radiation and thermal conductivity. Firing occurs at a very high speed of 10 ³ -10 ⁴ ° C / s, therefore, the foaming process is a combination of parallel endothermic chemical reactions, while the crystallization of the glass is suppressed, the bulk density of the granules decreases. In expanded clay, with isothermal heating, the content of the vitreous phase increases by 15-25%, its bulk density decreases to 200 kg / m ³ . As the granules are heated to the pyroplastic state and gases and vapors of bound water are released from the blowing agent, the granules are foamed, which increase in volume, mix and move with screws in the furnace. The presence of a dusting agent (alumina or building lime) protects the granules from sticking together, with the lining and screws of the furnace. Upon receipt of a particularly light granular porous material, together with granules, fine-grained quartz sand is fed into the furnace, which is then screened out for reuse. Foamed granules are fed through a tray to an electric tunnel-conveyor annealing furnace 20 with adjustable heating zones, where the selected temperature-time schedule of annealing is maintained by continuously adjusting the conveyor speed depending on the material, density, and granule size; this annealing allows to obtain granules without residual stresses, which increases strength and reduces water absorption of granules. The conveyor feeds the granules into the wiping drum 21, where the adhered granules are separated, and the surplus of the dusting agent that has not sintered with the granules is screened out (it returns to the dusting after screening). Then the granules are conveyor belts or bucket elevators are delivered to the finished goods warehouse 22.

The above-described method for producing granular porous materials provides stable, good quality products that have the following characteristics:

Characteristics Expanded clay Heat-insulating foamglass Concrete aggregate Bulk density, kg / m ³ 200-250 120-240 250-300 The ultimate tensile strength in the cylinder, MPa 1-2 0.3-2.4 2.4-3.5 Water absorption by volume,% up to 5 up to 1 up to 1 Granule size mm 5-15 5-15 5-15 Bulk thermal conductivity, W / (m · deg) 0.07-0.08 0.04-0.06 0,061-0,07

The advantages of the proposed method for producing granular porous materials are that grinding glass in a centrifugal elliptical mill of a through type increases productivity, and the addition of water (up to 5%), due to mechanical activation, gives the necessary hydration to the powder, which in turn is combined with isothermal and good mixing in a tunnel-auger furnace reduces the foaming temperature by 90 ° C and obtain a uniformly-porous honeycomb structure of the foam material, reduce the bulk density of the granules by 1.5 times with a simultaneous increase in strength and a decrease in water absorption.

The use of a reinforced screw granulator in the technological process allows to increase the density and improve the structure of raw granules, to produce granules of strictly specified sizes. An increase in the density of raw granules increases their thermal conductivity, which at high heating rates allows to obtain pores of the same size throughout the volume of the granules.

The use of an electric tunnel-auger foaming furnace allows you to create the necessary isothermal heating of the granules at a rate of 10 ³ -10 ⁴ ° C / s, which, along with mixing the granules, is necessary to obtain high-quality foam glass and expanded clay with a density of 200 kg / m ³ .

The presence of controlled heating zones in the tunnel-conveyor annealing furnace and smoothly adjusting the conveyor speed allows maintaining the optimal temperature-time graphs of annealing granules of various densities and sizes, which increases the strength of granules and reduces water absorption.

The use of an electric induction drying oven, an electric tunnel-auger foaming furnace and an electric tunnel-conveyor annealing furnace suggest that the inventive method of porous materials is a much more environmentally friendly production than the prototype.

Claims (1)

A method of producing granular porous materials, including crushing, weight dosing, grinding in a mill, drying granules, foaming granules with a separating medium and annealing, characterized in that the grinding is carried out in a centrifugal ellipse mill of passage type with powder moistening with water from 0.5 to 5% by weight and by the addition of a blowing agent, then screening is carried out on a classifier of finely ground hydrated powder with a specific surface of 6000 cm ² / g, mixed with a binder plasticizer, granulated on a reinforced screw gran through the nozzles, at the outlet, the granules are cut with a knife, and before dusting, the granules are doused to obtain the correct spherical shape, dusted, dried in an electric induction furnace at 420 ° C, foamed in a tunnel screw conveyor furnace at a temperature of 730-830 ° C and separated in the wiper drum.