Neutralisation technique of metallic mercury by immobilisation

FIELD: metallurgy.

SUBSTANCE: invention concerns industrial sanitation and environmental protection field, at usage in manufacturing and in domestic conditions of metallic mercury, its containing devices and facilities, and also of amalgams, and is intended for neutralisation of mercury at its ingress both on surfaces of different materials and into volumes (material, brick, concrete and so forth). Neutralisation technique of metallic mercury by immobilisation includes its oxidation by means of treatment by water solution of hydrogen peroxide. At that additionally to oxidation it is implemented mercury deposition by means of simultaneous or successive treatment by water solution of reagent, transferring metallic mercury into insoluble or sparingly soluble in water compound of natural or anthropogenic composition. In the capacity of reagent there are used water-soluble compounds of alkaline or alkaline-earth metals for instance, sulphates, phosphates or carbonates.

EFFECT: effectiveness increase of process at excluding of mercury - organic compounds formation.

5 cl, 5 ex

 

The invention relates to the field of industrial hygiene and environmental protection when used in the production and living conditions of metallic mercury containing devices, as well as amalgam, and is intended for disposal of mercury when released it as open surfaces of various materials and volumes (soil, brick, concrete etc).

It is known that metallic mercury is a substance of the first class of danger. Particularly dangerous mercury vapors and assimilated by living organisms through the respiratory organs in the process of aspiration.

It is also known that due to the high vapor pressure of mercury over its surface (even under water) concentration in the air at ordinary temperature may exceed the permissible in the residential area the size of the MPC (maximum permissible concentration) most nearly 45 thousand times. Due to this the number one priority when conducting demercurization of mercury contaminated surfaces and/or volumes is full mechanical or thermal destruction of metallic mercury or its translation in a fixed form stable chemical compounds (immobilization) with subsequent disposal of the latter.

For the disposal of metallic mercury by chemical immobilization suggested and use the camping in practice a considerable number of chemicals and their compounds, able to oxidize mercury and its transfer from the metal state in a sparingly soluble (preferably insoluble) in water Sol.

The most widely represented in the literature is often used to practice the compositions and methods that transform mercury into water-insoluble sulphide form HgS similar to natural cinnabar and metacinnabar (see, for example, domestic certificates of authorship for inventions No. 1051103; No. 2175664 - composition "e-2000+"; No. 2185413 - composition "103"; patent applications No. 95105191; No. 2003105728 - composition "102A" and others).

Common drawbacks of these solutions is, on the one hand, is not high enough, the kinetics of the processes that lead either to the necessity of repeated recurrence of operations immobilization of mercury, or to the necessity of prolonged exposure to a chemical reagent to metallic mercury that ethnologica, on the other hand, the application in most cases are quite rare and not readily available reagents. In addition, when the excess sulfur-containing reagent immobilization process in certain conditions can form water-soluble polysulfides mercury HgSx.

The number of known compounds (see, for example, certificates of authorship for inventions No. 2081198; No. 2148662; No. 2240337 and others), in particular, is sometimes used in the manufacturing method of immobilization of mercury using spirtitual races the thief, aimed at the transfer of mercury in a very poorly soluble in water (˜60 mg/l) form of iodides.

The main disadvantage of these solutions is the relatively high cost of both the iodine and its compounds. In addition, iodine is a highly corrosive and toxic element.

Known also numerous compositions (see, in particular, certificates of authorship for inventions No. 1151103; No. 1678878; application for invention No. 2003106197/04 and others), including the ones described in the literature and even featured in some of the standard materials intended for oxidation of mercury by chlorine, chlorcyclizine compounds, and some chloride (ferric chloride FeCl3etc) to make it insoluble in water (˜2.0 mg/l) calomel Hg2Cl2.

The main drawback of these methods is the possibility of transformation, with significant excess oxidant monovalent mercury chloride - calomel into ferrous chloride mercury - HgCl2- mercuric chloride, which is a highly toxic substance. In addition, most oxidizing agents containing active chlorine (bleach, sodium hypochlorite, ferric chloride, dichloramine and others), often discolor, and sometimes destroy the materials machined surfaces, which in some cases is unacceptable.

In a separate group can is to be collected by known methods of immobilization of mercury compounds, produce in the course of their use of active oxygen and transferring the metallic mercury in a sparingly soluble in water (˜50 mg/l), oxide - HgO, similar to the natural montroydite (see, for example, certificates of authorship for inventions No. 266727; No. 380729; and others, as well as recommended and widely used in practice oxidants - pyrolusite MnO2, manganese-acidic potassium - KMnO4and others).

Thus, in the method of immobilization of metallic mercury copyright certificate №380729, which is an analog of the claimed invention, the oxidation of mercury is the strongest oxidizing agent is hydrogen peroxide (H2O2in the form of a molecular complex with urea, CO(NH2)2which is essentially obvious similarity to known antiseptic drug - hydropenia. The use of urea in the composition should lead to the formation of insoluble mercury-organic complex R·(HgO), where R is an organic radical formed by the molecule of urea.

The main disadvantages of this analog is inefficient, not allowing to make full immobilization of metallic mercury, as well as the probability of formation in the process are highly toxic mercury-organic compounds.

The closest to the technical nature of the claimed invention is adopted is output as a prototype method of immobilization of metallic mercury copyright certificate №266727, in which the treatment of mercury contaminated surfaces and places the accumulation of implementing a 5%aqueous solution of hydrogen peroxide H2About2.

The main disadvantage of the prototype as well as analogue, is its lack of efficiency, which does not allow the reduction of the concentration of mercury vapor over the surface to the desired limit values. In addition, created on the surface of the mercury film its oxide is unstable, as the hydrogen peroxide.

An object of the invention is to increase the efficiency of the immobilization process of metallic mercury by depositing it in the form of insoluble or sparingly soluble in water compounds with simultaneous exclusion of the probability of formation of mercury-organic compounds.

The problem is solved in that in the method of disposal of metallic mercury immobilization, including oxidation by treatment with an aqueous solution of hydrogen peroxide, according to the invention in addition to oxidation carry out the process of deposition of mercury by simultaneous or sequential treatment with an aqueous solution of reagent translating metallic mercury in an insoluble or sparingly soluble in water connection natural or man-made structure, and as a reagent used motorstore what's the connection alkaline or alkaline-earth metals, for example sulfates, phosphates or carbonates. This combination of features allows you to perform a complete immobilization of metallic mercury as a result of formation of insoluble - basic sulphate of mercury HgSO4·2HgO, similar to the natural mineral shuettite, phosphate mercury Hg3(PO4)2or very poorly soluble in water is a basic carbonate of mercury HgCO3·2HgO and, consequently, non-toxic and non-biodegradable under normal conditions of mercury compounds.

Examples of the complete method.

Example 1. The interaction of metallic mercury with hydrogen peroxide H2About2similar to the prototype.

The hanging mercury mass 4,3799 g at a temperature of 25°treated With 5 ml of 20%hydrogen peroxide H2O2. After 1-2 min of beginning the process of outgassing. After 24 hours the surface of metallic mercury was covered with a solid gray color, easily separating from mercury and passing into solution with the formation of unstable suspensions. The precipitate dark gray color is dissolved in dilute nitric acid, HNO3. Radiograph of the sediment shows that the oxidation of metallic mercury hydrogen peroxide, a precipitate of oxide of mercury (II) (HgO), the solubility of which is 49-51 mg/l H2O at 25°C.

The decline in the mass of mercury 0,01895 g with a surface area of a sample S=2,27 cm2that is Corot response of metallic mercury in a solution of hydrogen peroxide is of 20.9 mg/cm 2·h.

Example 2. The interaction of metallic mercury with hydrogen peroxide H2O2with the addition of sulfate lithium Li2SO4.

The hanging mercury mass 2,45985 g at a temperature of 25°treated With a solution containing 5 ml of 20%hydrogen peroxide and 0.5 ml of 20%aqueous solution of sulfate of lithium (Li2SO4). After 3-5 min observed intensive gassing and heating the solution to a temperature of 50-60°C. the Process of reacting flows 25 minutes, resulting in a precipitate of lemon-yellow color.

Radiograph of the sediment showed that the oxidation of metallic mercury hydrogen peroxide with the addition of lithium sulfate consists of a basic sulfate mercury (II) (HgSO4·2HgO), similar to the natural mineral shuettite, with a solubility of 30 mg/l N2At 16°C.

The decline in the mass of mercury is 0,50225 g with a surface area of a sample S=1,09 cm2the speed of response of metallic mercury in the hydrogen peroxide solution is 3300,0 mg/cm2·h.

The increase in the rate of dissolution of mercury due to the additive of lithium sulfate in comparison with example 1 (prototype) is ≈4000 times.

Example 3. The interaction of metallic mercury with hydrogen peroxide H2About2with the addition of magnesium sulfate MgSO4.

The experiment on the oxidation of metal mouth is and weight 2,45958 g 5 ml of 5%hydrogen peroxide with the addition of 0.5 ml of 20%aqueous solution of magnesium sulfate (MgSO 4) produces excessive gassing and heating the solution to a temperature of 50-60°C. the Process of reacting flows 25-30 minutes

Radiograph obtained precipitate lemon-yellow color showed the presence of oxide (HgO) and primary sulfate mercury (II) HgSO4·2HgO having a solubility ˜30 mg/l N2At 16°C.

Example 4. The interaction of metallic mercury with hydrogen peroxide (H2O2with the addition of sodium phosphate Na3(PO4).

The experiment on the oxidation of metallic mercury by weight 2,45985 g 5 ml of 5% hydrogen peroxide with the addition of 0.5 ml of 20%aqueous solution of sodium phosphate Na3(PO4). The process of reacting flows 45-60 minutes.

Radiograph obtained precipitate yellowish-white colour showed the presence of a water-insoluble phosphate of mercury Hg3(PO4)2.

Example 5. The interaction of metallic mercury with hydrogen peroxide H2About2with the addition of sodium carbonate Na2CO3and nitric acid HNO3.

After processing the sample of metallic mercury by weight 2,45985 g 5 ml of 5%hydrogen peroxide was added 0.5 ml of a 20%aqueous solution of sodium carbonate Na2CO3and 0.5 ml of 1%aqueous solution of nitric acid, HNO3.

The result was obtained red-brown precipitate of a basic carbonate of mercury (II) (HgCO3·2HgO).

In affect, the, the use of this method increases the efficiency of immobilization of metallic mercury.

1. The method of disposal of metallic mercury immobilization, including oxidation by treatment with an aqueous solution of hydrogen peroxide, characterized in that it further with oxidation simultaneously or sequentially carry out the deposition of mercury by treatment with an aqueous solution of reagent translating metallic mercury in an insoluble or sparingly soluble in water connection natural or man-made structure.

2. The method according to claim 1, characterized in that the reagent is used as a water-soluble sulfates of alkali metals.

3. The method according to claim 1, characterized in that the reagent is used as a water-soluble magnesium sulfate.

4. The method according to claim 1, characterized in that the reagent is used as a water-soluble phosphates of alkali metals.

5. The method according to claim 1, characterized in that the reagent is used as a water-soluble carbonates of alkali metals with the addition of nitric acid.



 

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5 cl, 3 tbl, 3 ex

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