RU2171150C1 - Method of processing of toxic wastes - Google Patents

Abstract

FIELD: processing of highly toxic wastes, mainly, ashes and slags of incinerators. SUBSTANCE: method consists in that ash, crushed slag, fillers and portland cement are subjected to combined grinding in presence of neutralizing additives for 5-25 min. Ground product is structurized by agglomeration into spherical granules and then, shell-capsule of cement- silicic mortar is formed by palletizing on granule surface. EFFECT: practically full neutralization of wastes from burning of toxic household wastes with content of harmful substances in processing products being far below the level of maximum allowable concentration and amounting to 20 mg/l. 1 tbl

Description

 The present invention relates to the field of processing highly toxic waste, mainly ash and slag from incinerators.

Known thermal methods of processing and disposal of solid household waste (MSW), including pre-crushing waste, feeding it to a device for heat treatment with subsequent burning and removal of combustion products (see, for example, RF patent N 2070548, class. B 09 B 3 / 00, 1996, RF patent N 2135305, class B 09 B 3/00, 1999). However, as the experiments showed, even the high temperature of the heat treatment, reaching 1700 ^o C, does not reduce the content of harmful substances in the products of incineration plants incineration - ash and slag. Therefore, in the future, when ash and slag are buried at special landfills, toxic substances are washed out of them and, as a result, dangerous pollution of the territory adjacent to the landfill occurs.

 There are also known methods of processing ash and slag from incinerators by introducing them into the molding mixture for the manufacture of building products (see, for example, the book by S. S. Yufit. "Incinerators - trash in the sky." - N. Novgorod, 1999 - S. 29). However, as experience with the use of such products has shown, toxic metals can also be washed out of molded blocks, where ashes and slags are in bound form.

 Closest to the proposed technical essence is a method of processing toxic waste, mainly ash and slag from incinerators, including mixing waste with a binder, additives and fillers, subsequent structuring of the mixture and heat treatment (see, for example, RF patent N 2125915, cl. B 09 B 3/00, 1992). In the known method, industrial and household waste is neutralized by processing them at elevated pressure and temperature in the presence of corrective additives. However, despite the presence in the final products of processing harmful substances in a bound or converted into a harmless form, this method does not provide complete neutralization of highly toxic substances.

 The purpose of the invention is to increase the efficiency of processing toxic waste.

 This goal is achieved by the fact that in the method of processing toxic waste, mainly ash and slag from incinerators, including mixing waste with a binder, additives and fillers and subsequent structuring of the mixture, ash, crushed slag, fillers and Portland cement are subjected to joint grinding in the presence of neutralizing additives within 5-25 minutes, the grinding product is structured by agglomeration into a spherical granulate, after which a shell-capsule is formed on the surface of the granules and h cement-siliceous solution.

 The method is as follows. Slag is preliminarily passed through a jaw crusher. Then the ash, crushed slag, filler, for example, building sand and Portland cement, preferably mechanically activated, in the presence of neutralizing agents taken from the lime group (quicklime or quicklime), alkali, is subjected to joint grinding for 5-25 minutes, followed by agglomeration of the product grinding by any method providing spherical granules, for example, by rolling on a disk granulator, pressing on hole rollers, etc. Then, on the surface of the granules using a special device for encapsulating granular material (see, for example, RF patent N 2091155 "Device for encapsulating granular material", 1995), a capsule shell of the required thickness is formed from a cement-siliceous solution, and the resulting capsule is used either for filling the foundation of roads and as technogenic soil for the restoration of ravines and quarries, or as a filler in the manufacture of building products (plates, side stone, blocks, small architectural forms, etc.).

 The essence of the proposed method is as follows. Agglomeration of a finely dispersed binder-Portland cement mixture, a mixture of ash and slag from incinerators, sand and neutralizing agents that neutralize them with harmful substances in the presence of water binds highly toxic solid waste incineration into a sufficiently dense, waterproof and durable agglomerate with a particle size of 5 to 5 40 mm. Due to this, the surface of the chemical exchange of particles of particularly harmful finely dispersed combustion products, especially fly ash, is significantly reduced. The formation on the surface of the agglomerate of a durable shell-capsule of the required thickness provides maximum additional isolation of the harmful substances contained in the waste incineration.

 The following are examples of the proposed method.

 Example 1. Slag is preliminarily passed through a jaw crusher. Then ash and slag waste (ash + crushed slag - 52 wt.%), Building sand (18 wt.%), Mechanically activated cement (28 wt.%) And a neutralizing additive - slaked lime (2 wt.%) Are subjected to joint grinding in vibration ball mill for 5 minutes. The resulting mixture is agglomerated by rolling on a plate granulator, where the mixture is moistened with water and pelletized into 5-20 mm granules. Then the raw granules are fed to an encapsulation device, where a capsule shell of 0.5-1.0 mm thickness is formed from a cement-siliceous mortar (mechanically activated cement: silica fume: building sand - 26: 2: 72). The resulting capsule is used either immediately as a filler in the manufacture of concrete products, or after daily exposure in natural conditions as a backfill.

 Example 2. The technology of processing toxic waste - according to example 1, but the grinding of the initial mixture is carried out in a through tube mill for 15 minutes.

 Example 3. The technology of processing toxic waste - as in example 2. In this case, the joint grinding of the initial mixture is carried out for 25 minutes, and the grinding product is subjected to agglomeration by pressing on hole rollers.

 The experiments showed that the use of the proposed technical solution beyond the stated conditions for the processing of toxic waste does not allow to achieve the goal.

 The table shows examples of the implementation of the method and properties of the resulting product in comparison with the prototype.

 Analysis of the data given in the table shows that the proposed method for processing highly toxic waste from incinerators provides almost complete neutralization: the content of harmful substances in processed products is many times lower than the required MPC level, which creates the prerequisites for their wide use as an environmentally friendly product. The method can be used for the processing of dispersed waste from the metallurgical, chemical, mining, radio engineering industries, energy wastes (ashes and slags of thermal power plants), contaminated soils, etc.

Claims (1)

 A method of processing toxic waste, mainly ash and slag from incinerators, including mixing waste with a binder, additives and fillers and subsequent structuring of the mixture, characterized in that the ash, crushed slag, fillers and Portland cement are subjected to joint grinding in the presence of neutralizing additives for 5 -25 min, the grinding product is structured by agglomeration into a spherical granulate, after which, by rolling, on the surface of the granules, a cement-silica shell-capsule is formed of solution.

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