RU2299100C2 - Method of detoxification of destroyed industrial building fragments polluted with lewisite and conversion products thereof - Google Patents

Abstract

FIELD: chemical weapons destruction.

SUBSTANCE: invention relates to detoxification of polluted former lewisite production objects and, in general, consists in grinding building materials and treating them with reagents. According to invention, part of building, prior to be destroyed, is moderately sprinkled through atomizer with saturated calcium hydroxide solution or with aqueous extract of cement powder with pH =10, which ensures transformation of lewisite and conversion products thereof into physiologically inactive, insoluble, nonvolatile, and environmentally non-dangerous form. Grinding is continued until fraction = 20 mm is obtained, which is simultaneously sprinkled with the same solution. Further, ground building materials are mixed with cement mortar at a rate of 1 part of building materials with 3-6 parts sand, 1 part cement, and amount of water sufficient to form pappy mass. Well mixed mass is charged into mold and held therein until stable solid material is obtained suitable for manufacturing desired-destination products.

EFFECT: enhanced efficiency of lewisite and its conversion products detoxification, and reduced consumption of materials required for detoxification.

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Description

According to the "Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction" of January 13, 1993, each country party to the international treaty, including Russia, must destroy all chemical weapons production facilities and ensure the rehabilitation of industrial sites .

The present invention relates to the field of destruction of chemical weapons, in particular to the detoxification of building elements contaminated with toxic substances (OM) of the lewisite production plants.

During the production of lewisite, elements of the building materials of the shops turned out to be substantially contaminated with lewisite and its conversion products.

In this regard, the development of methods for the effective detoxification of lewisite contaminated building structures of shops is a very urgent problem.

There is a method of detoxification of building elements of the lewisite production workshops by alkaline hydrolysis, which consists in processing these elements with 20% sodium alkali (NaOH) at a temperature of 90-100 ° C (TACIS program for the preparation and disinfection of the former production of chemical weapons and the surrounding area at Caprolactam OJSC, No. 4, August 2001). In this case, there is a complete detoxification of lewisite and its conversion products with the formation of an inorganic salt - sodium arsenite, well soluble in water. To extract sodium arsenite from building elements (mainly silicate bricks), which is a poison of the first hazard class, pre-crushed bricks are repeatedly washed with warm water. Wash water, in turn, is detoxified by precipitation of arsenic in the form of a sparingly soluble salt. The latter is sent to the disposal site of arsenic-containing waste. In water thus purified, the arsenic and lewisite content should be ≤ MPC in water (MPC _As = 0.01 mg / l, and MPC _lewisite = 0.0002 mg / l). Fragments of the building structures of buildings using this technology should be washed from arsenic and lewisite to the maximum permissible concentration in the soil (2 mg / kg). Then they go to the dump.

The process of destruction of production shops infected with lewisite and products of its transformations includes the following stages:

1. the treatment of walls and other parts of the building with water in order to reduce dust formation in the process of destruction;

2. destruction of building structures of the shop;

3. crushing and sorting fragments of building materials;

4. processing of materials obtained in claim 3 with an aqueous solution of sodium alkali;

5. washing alkali-treated crushed materials with water in order to purify the latter from soluble forms of arsenic (sodium arsenite);

6. treatment of wash water with reagents to obtain sparingly soluble arsenic compounds;

7. separation of sediment from the water mass and its direction to the landfill for the disposal of arsenic-containing waste;

8. water can be partially directed to the preparation of an alkaline solution;

9. shredded and deactivated fragments of building materials are sent to the dump, provided that the content of lewisite and arsenic in them does not exceed the MPC standards in the soil. If the content of arsenic and lewisite exceeds the MPC value, then the processing of building material is repeated until this value is reached.

Significant disadvantages of the prototype are:

1. The method of detoxification of fragments of building materials contaminated with lewisite and its conversion products proceeds in two stages (the stage of processing building fragments with a solution of sodium alkali and the stage of processing an aqueous solution of sodium arsenite in order to obtain an insoluble arsenic compound). The stage of washing bricks contaminated with arsenic to the MPC level in the soil is complex, multi-stage and difficult to reach for heavily contaminated fragments.

2. The alkaline treatment process is carried out at a temperature of 90-100 ° C.

3. The sparingly soluble arsenic compounds formed during the treatment of washing water with reagents are to be buried in a special landfill for arsenic waste.

4. Fragments of building structures that have passed the detoxification stage do not lie down for disposal and must be sent to a dump according to the hazard class of these wastes.

5. The relatively high cost of implementation of the considered method of detoxification of old shops for the production of lewisite. Especially high are the costs of creating a specialized landfill for the disposal of arsenic-containing waste.

The aim of the invention is to increase the efficiency of the detoxification of lewisite and its conversion products, as well as reducing material costs for its implementation.

This goal is achieved in that the detoxification of fragments of building materials in accordance with the invention is carried out in contrast to the prototype as follows.

Crushed to a certain size, the building material, mainly silicate brick, is impregnated with calcium hydroxide (milk of lime) or an aqueous extract of powdered cement, exhibiting an alkaline reaction of pH≥10. At the same time, lewisite and its conversion products pass into insoluble calcium arsenite, which is held in fragments of building materials (bricks) in places where toxic substances are concentrated, while losing physiological activity. The building material thus treated (silicate brick) is mixed with ordinary building cement mortar, which is a mixture of cement with sand and water. The resulting mixture of fragments of building materials with cement mortar is directed into a mold and allowed to turn the system into a solid mass. The resulting product is used for its intended purpose.

Thus, detoxification by treating fragments of building products with calcium hydroxide (milk of lime) or an aqueous extract of powdered cement with a pH≥10, followed by cementing the resulting mass and obtaining solid blocks of a given shape are essential features of the invention, providing effective detoxification and removal of physiological activity lewisite and its transformation products by converting them into an inorganic insoluble form - calcium arsenite.

These signs are unknown in open sources of scientific and technical information and are new.

The invention is carried out as follows.

Part of the building of the lewisite production workshop, before being destroyed by a spray (shower) installation, is moderately irrigated with a saturated solution of calcium hydroxide or with an aqueous extract from cement powder. The solutions have a pH≥10. This measure has a dual purpose: 1 - to reduce dust formation during the destruction of structures and 2 - to detoxify the outer layers of the building, most likely contaminated with lewisite and its conversion products. Further, mechanical destruction of the part of the building processed in this way is carried out, crushing of fragments of building materials to a fraction of ≤20 mm while moderate irrigation with the same solution. The crushed building material is then mixed with cement mortar. The mixture consists of the following parts by volume: 1 part of building material, 3-6 parts of sand, 1 part of cement and water in an amount sufficient to create a mushy mass. The resulting well-mixed mixture is introduced into the form and maintained until a stable solid mass is formed. The mass according to its toxicological characteristics belongs to the 5th hazard class and can be used in the form of products (for example, blocks, plates) for their intended purpose.

Products are monitored for lewisite content according to the procedure [1] and to the content of water-soluble arsenic compounds according to the method [2].

The following are examples of specific embodiments of the invention.

Example 1

Take 3 kg of an average sample of fragments of a brick wall of one of the buildings for the production of lewisite. According to the results of analyzes (conducted at an accredited laboratory center of the Research Institute of Chemistry), the lewisite content was not found in it, the lewisite oxide content was 230 mg / kg and the total arsenic content was 10,000 mg / kg. Lewisite oxide, although it is a non-volatile compound, nevertheless possesses physiological activity of an external cutaneous action similar to lewisite.

Previously, the masonry fragments are impregnated with a saturated solution of calcium hydroxide (milk of lime). It is dried for 24 hours in air, then impregnated with a lime solution for the second time and wet milled to particles ≤20 mm in size. Next, 1 part (by weight) of the crushed brick is mixed with 3 parts of sand and 1 part of cement. The mixture is diluted with water to a mushy state, mix well and leave the mixture to completely harden in air (full setting of cement is 28 days). At the end of the maturation process of the mixture, part of the cement block is used to prepare an aqueous extract and is analyzed for the content of arsenic and lewisite oxide.

In similar conditions, a water extract is prepared from the original brick taken to prepare the cement block.

The results are shown in table 1.

Table 1 The content of arsenic compounds in brick (sample No. 1) treated with milk of lime and a cement block. Name of indicator (sample No. 1) Content, mg / kg Brick Cement block Water extract brick cement block Lewisite oxide 230 0.05 0,070 <0.0001 Arsenic is common 10,000 2050 1300 <0.01

Example 2

3 kg of an average brick sample taken from fragments of masonry of one of the buildings is watered from the sprayer with an aqueous extract from cement powder. The brick sample is dried and watered again until completely saturated. Grind to pieces no larger than 10-20 mm, load into a mixer, add 3 parts by weight of river sand, 1 part cement and water, mix, place the mixture in a mold and allow the sample to mature. The initial brick, cement block and water extract from them are analyzed for the content of arsenic and lewisite oxide. The results are presented in table 2.

table 2 The content of arsenic compounds in the brick (sample No. 2), treated with an aqueous extract of cement powder, and in the cement block. Name of indicator (sample No. 2) Content, mg / kg Brick Cement block Water extract brick cement block Lewisite oxide 140 <0.05 0,060 <0.0001 Arsenic 6800 1250 1200 <0.01

Example 3

Brick containing 8.4 mg / kg lewisite oxide and 1320 mg / kg total arsenic was artificially contaminated with lewisite. For this, 4.8 mg of lewisite was added to a brick weighing 3 kg. Next, the brick was processed, as in examples 1, 2. The results of the analysis are shown in table 3.

Table 3 The content of arsenic compounds in the brick with added lewisite (sample No. 3), processed as in examples 1 and 2, and in the cement block. Name of indicator (sample No. 3) Content, mg / kg Brick Cement block Water extract brick cement block Lewisite 1,6 <0.05 0.004 <0.0001 Lewisite oxide 8.4 <0.05 0.05 <0.0001 Arsenic is common 1320 330 64 <0.01

The calculation method and testing of the resulting cement blocks, including detoxified fragments of building materials (silicate brick), previously contaminated with lewisite, using living organisms, established the toxic hazard class. The hazard class of water extract from cement blocks corresponds to the fifth class.

From examples 1-3 it follows that the proposed method of detoxification of building materials infected with lewisite, which consists in processing these materials (silicate brick) with an aqueous extract of cement powder or with milk of lime with pH≥10 followed by cementing fragments of building materials, allows to obtain non-toxic or practically low-toxic cement blocks, characterized by a fifth class of toxic hazard. In aqueous extracts from cement blocks, the concentration of arsenic-containing components is lower than the maximum permissible concentration for water.

Information sources

1. Recommendation P2 / 6-99 "Methodology for measuring the mass concentration of lewisite in samples of concrete coatings by gas chromatographic method." M., 1999.

2. A.A. Nemodruk. Analytical chemistry of arsenic. M., 1976, p. 59.

Claims (1)

The method of detoxification of fragments of building materials from workshops contaminated with lewisite and products of its transformation, which consists in crushing building materials and treating them with reagents, characterized in that before destruction, part of the building using a spray gun is moderately irrigated with a saturated solution of calcium hydroxide or with an aqueous extract from a cement powder with pH≥ 10, providing the translation of lewisite and its conversion products into a physiologically inactive, insoluble and non-volatile form, not dangerous to the environment s, while crushing of building materials is carried out to a fraction of ≤20 mm with simultaneous moderate irrigation with the same solution, which is further mixed with cement mortar in the ratio of 1 part of building material, 3-6 parts of sand, 1 part of cement and water in an amount sufficient to create a mushy mass, and the resulting well-mixed mixture is introduced into a mold and maintained until a stable solid mass is formed, suitable for the manufacture of products used for their intended purpose.