SU880149A1 - Method for solidifying wastes - Google Patents

Description

(54) METHOD OF WASTE CURING

The invention relates to the field of processing radioactive waste of low and medium activity levels (10 C / l) and other toxic substances, in particular, transferring them to the cured state by incorporation into an inorganic binder. A large amount of such waste is generated in nuclear power plants.

Portland cement 1 is known to harden radioactive waste in almost all countries.

Waste is subjected to cementing with a salt content not exceeding 150 g / dm, which, with a water-to-cement ratio of 0.6-0.7, corresponds to a salt content in the cured product of 4-5%. With a higher salt content, a durable cement stone is not obtained. The disadvantage of these methods is the use of scarce building material for recycling.

The closest technical solution to the present invention is a method for curing waste containing radioactive isotopes and other toxic substances by mixing with metallurgical granulated slag or slag portland cement 2. According to the method, the waste is cured in the form of liquids, sludge or sludge, which

have various sources of formation, such as industrial, agricultural or household waste, and metallurgical slags, which are hydrated in an alkaline medium and have the following composition, are used as a binder. %: CaO30-50

SiOa25-40

ABOS8-20

ten

FeO5-15

MgO2-8

Waste in the form of liquids, slimes, or sludge is mixed with the following substances (per 100 parts by weight of waste):

15

5-35 weight. slag (having the above composition);

0.02-15 weight. alkaline agents; 0.2-30 weight. h (preferably 0 wt. h) activating agents;

20

O-150 weight. hours (preferably 5-30 weight. h.) pozzolana, fly ash or clinker, and optimally from 0 to 2 weight. including emulsifying agents and / or hydrophobic materials. The result is products in the form of loose powders or granules, which the authors recommend to use as fertilizers or sorption materials.

The disadvantages of the prototype method include the fact that in this process not a strong monolith is formed and the water resistance of the resulting material is low. The high content of FeO (up to 15%) in the recommended slags also negatively affects the quality of the final product, as it reduces the strength of the final product. The aim of the invention is to obtain a solid monolith with a high content of dry residue of waste, suitable for safe disposal. This goal is achieved by the fact that in the method of solidifying wastes containing radioactive isotopes and other toxic substances, by mixing with metallurgical granulated sclac or slag portland cement, the metallurgical granulated sclac with a specific surface of 2800-4000 is mixed with wastes containing radioactive isotopes and other toxic substances water trestle ratio of 0.2-0.6 and a temperature of 20-90 ° C. In addition, slag Portland cement containing from 20 to 80 May is used as a trash. % slag. Waste nuclear power plants, as a rule, have an alkaline reaction and contain a large amount of surface-active substances. This avoids the additional introduction of alkaline substances necessary for hydration and plasticizers, which allows a significant increase in the content of waste in the cured product. The proposal aims to solve the problem of obtaining the final product with mechanical strength, satisfying the IAEA transport rules (100 kgf / cm) and having water resistance based on portland cement (leaching rate - X day). Crushed blast-furnace and steel-smelting slags with a specific surface area of 2800-4000 can be used as metallurgical slabs. To speed up the process of setting the displacement with the slag, a solution or slurry with a temperature of up to 90 ° C can be supplied. The possibility of carrying out the process over a wide range of temperatures (from 20 to 90 ° C) without deteriorating the quality of the solid material that allows or creates a continuous process chain with feed hot solution from the cube of the evaporator directly into the apparatus for displacing it with the existing one, or storing the waste in intermediate tanks with subsequent curing in the semi-continuous or periodical apparatus chesky action. When the water ratio is between 0.2-0.6% and 30%, the imitation can be replaced by the anhydrous components of the waste, which will correspond to 25-26% by weight of the dry matter of the waste in the curing product. This value is 4-5 times higher than the salt content in the compound based on portland cement and mortar with a salt content of 150 g / dm. Example. 1. Waste, concentrated to 40% of free water content, is mixed with metallurgical slag of the following composition, weight. %: SiO235.56 A120z10.76 FeO0.34 MpO0.10 CaO42.05 MgO7.46 S 1.80 NasO0.36 K2O0.49 Per 100 wt. hours of waste add 140 weight. including crushed slag with a specific surface of 3500 sy- / g. After stirring, the mixture remains to solidify at ambient temperature. As a result, a strong myolite is formed with a density of 2 g / cm and a compressive strength of 127 kgf / cm. The leaching rate of the water-soluble waste components is about 10 g / cm day. The dry matter content of the waste in the final product is 25 May. % 2. The dehydrated waste is mixed with water or a radioactive solution and metallurgical slag of the following composition, weight. %: SiOs 38.46; ABOZ 9.06; FeO 0.21; MpO 1.30; CaO 45.64; MgO 3.46; S 1.06; Ti02 0.17; Na2O 0.43; K2O 0.60. 100 weight. hours of waste add 66 wt. including hot (50 ° C) water or radioactive solution and 230 weight. including crushed slag of the composition with a specific surface area of 3500. After stirring, the mixture is left at ambient temperature. As a result, a solid monolith with a density of 2 g / cm and a compressive strength of 108 kgf / cm is formed. The leaching rate of water-soluble components is 10 g / cm day. The dry matter content of the waste in the final product is 27 May. % 3. Concentrates of industrial wastes containing sulphates, phosphate, nitrate and sodium chloride and chromium hydroxide with 20% humidity are mixed with metallurgical slag of the following composition (with a specific surface area of 3500), weight. %: SiO2 36.24; HOSP 12.59; FeO 0.37; MpO 0.86; CaO 39.03; MgO 8.39; S 0.54; Na2O 0.35; KgO 0.67. Mixing is carried out at 20 ° C and a water ratio of 0.3. At the same time, the content of b-mole in the cured product is 20%. After a day the mixture hardens. The strength of the material after 28 days of exposure 200 kgf / cm. Leaching rate

Claims (2)

Claim 1. Method of curing waste containing radioactive isotopes and other toxic substances by mixing with metallurgical granulated slag or slag Portland cement, characterized in that, in order to obtain a monolith with a high content of dry residue of waste suitable for safe disposal, mixing is carried out at a binding ratio of 0 , 2–0,6 with a specific binder surface of 2800–4000 cm ² / g at a temperature of curable waste of 20–90 ° C. 2. The way pop. 1, characterized in that as a binder using slag Portland cement containing 20 - 80 May. % slag.