KR20120062703A - Solid mineral composition, method for preparing same and use thereof for reducing heavy metals in flue gas - Google Patents

Abstract

The present invention relates to a solid inorganic composition for reducing heavy metals, particularly mercury, present in the flue gas, a process for preparing such a solid inorganic composition, and to contacting the solid inorganic composition with the flue gas to reduce heavy metals, particularly mercury, present in the flue gas. To the use of said composition for the purpose of

Description

Solid inorganic composition for reducing heavy metals in flue gas, preparation method thereof and use thereof {SOLID MINERAL COMPOSITION, METHOD FOR PREPARING SAME AND USE THEREOF FOR REDUCING HEAVY METALS IN FLUE GAS}

The present invention relates to a composition for reducing heavy metals in a flue gas comprising an inorganic compound.

Heavy metals, especially mercury, are toxic compounds present in the flue gas, especially in gaseous form, and their emissions are generally strictly regulated. The term "heavy metal" refers to metals having a density of mainly greater than 5,000 kg / m 3, especially the most common heavy metals which are generally regulated, namely lead, chromium, copper, manganese, antimony, arsenic, cobalt, nickel, vanadium, cadmium, thallium And mercury, preferably lead, thallium, cadmium and mercury, in particular mercury. Such metals may exist in elemental state or in ionic form.

The reduction of heavy metals present in the flue gas is generally carried out in the art by carbonaceous compounds such as activated carbon, lignite coke and the like. The choice of type (s) of carbonaceous compounds depends in particular on the level of regulation that should not be exceeded for this type of contaminant.

In many situations, in the case of waste incinerators, the initial emission levels of certain heavy metals sometimes exceed effective regulatory levels, which necessitates the absolute reduction of these kinds of pollutants to significant levels sometimes. The carbonaceous compound may be applied by itself or in the form of a mixture with a basic reagent, injected into the gas in the form of particles or in the form of a powder in a fixed bed; Solid particles are trapped downstream, for example in fabric filters.

No one disputes the effectiveness of carbonaceous compounds to reduce heavy metals. Nevertheless, the use of such carbonaceous compounds in flue gases has two major disadvantages:

An increase in the total organic carbon content in the dust present at the discharge of the flue gas in which the carbon content is strictly regulated;

Higher flammability risk due to high temperature of the gas to be purified.

One improvement provided by those skilled in the art to solve the ignition problem of carbonaceous compounds has been to use them in mixtures with non-combustible materials such as lime. This method actually reduced the ignition risk of carbonaceous compounds but unfortunately did not completely suppress it. Indeed, hot spots may still appear in places where carbonaceous compounds accumulate, especially at the intrusion of air, even at low temperatures (eg 150 ° C.).

For example, document US 6,582,497 describes mixtures of coal and alkali compounds impregnated with coal or halogenated compounds to reduce mercury in the flue gas. However, this document does not provide any information regarding the possible doping of inorganic compounds and the effect on the reduction of mercury in flue gases.

The document US 2008/028932 discloses the use of oxidizing agents, preferably calcium hyperchlorite, to improve the mercury reduction in gas streams. Calcium hydrochloride is added upstream of the adsorbent injection to react with the adsorbent. However, calcium hydrochloride is a corrosive, oxidizing and environmentally harmful compound and is known to have problems in use.

Finally, the document WO 2007/053786 describes the use of chlorides or other oxidants which are added together with coal prior to combustion, oxidizing mercury into salts and promoting their subsequent capture.

Carbonaceous compounds are generally expensive compounds and the application of such carbonaceous compounds is difficult to integrate into the overall process for flue gas treatment and often requires the removal of nitrogen-containing contaminants. Removal of nitrogen oxides by the catalytic method is generally carried out at gas temperatures in excess of 200 ° C. at which the carbonaceous compound can burn in the presence of oxygen. For good compatibility with the steps of the method using the carbonaceous compound, cooling of the flue gas and heating of the flue gas need to be carried out alternately. This means significant energy losses and cost increases. Therefore, as long as there is an ignition problem caused by the carbonaceous compound, it is difficult to integrate the carbonaceous compound into the flue gas treatment method.

See ES 8704428, ES 2136496, and "GIL, ISABEL GUIJARRO; ECHEVERRIA, SAGRARIO MENDIOROZ; MARTIN-LAZARO, PEDRO JUAN BERMEJO; ANDRES, VICENTA MUNOZ, Mercury removal from gaseous streams.Effects of adsorbent geometry, Revista de la Real Academia de Ciencias Exactas, Fisicas y Naturales (Spain) (1996), 90 (3), pp. 197-204 "] describe the use of sulfur as a reagent, without carbon, to reduce heavy metals, especially mercury. . Sulfur is deposited on an inorganic support such as natural silicate. Such formulations overcome the disadvantages of the aforementioned carbonaceous compounds. In this case, the silicates are considered to be relatively inert to the contaminants to be reduced; Silicates are captured by reaction with sulfur-containing compounds and generally form sulfides.

Unfortunately, silicates functionalized by sulfur-containing compounds are disadvantageous in use as they involve an expensive, dangerous manufacturing process that is dangerous and burdensome to handle. For example, document ES 8704428 describes a process for sulfiding silicates by oxidizing hydrogen sulfide in a well-defined molar ratio to adsorb elemental sulfur on the silicates. The handling of very toxic and extremely flammable hydrogen sulfide is dangerous and the strict molar ratios required to avoid any subsequent oxidation reactions are very limited. Document ES 2136496 provides a similar teaching, describing a method of sulfiding natural silicates to retain metal vapors.

Another example is described in document US 2007/0267343, which provides for the capture of heavy metal particles in the aqueous phase in the presence of a complexing agent compound, preferably a phosphorus-containing compound, in particular phosphate. In this way, a complex is formed between the phosphate and the metal to be trapped in the water phase, which does not have very high solubility and prevents the release of metal in natural or induction leaching processes and / or digestion processes in humans or animals. Decrease. Therefore, the water phase in which the complexing reaction occurs is essential, and it is difficult to apply it to the mass reduction of mercury in the flue gas by the powder compound alone.

Patent EP 1732668 B1 provides for the use of nonfunctionalized inorganic compounds, in particular halloysite, for the reduction of heavy metals, in particular mercury. However, the efficiency of the halosites for mercury reduction appears to be limited compared to activated carbon and a priori requires excessive usage. In addition, the reduction of heavy metals by nonfunctionalized inorganic compounds such as halosites is carried out by (pyrogenic) adsorption, whereby the efficiency decreases with increasing temperature.

It is an object of the present invention to provide a composition wherein, as mentioned in the introduction, an inorganic compound is doped with a halogen salt and is selected from the group consisting of halosite, calcium or magnesium carbonate or hydroxide, sodium carbonate, mixtures and derivatives thereof, It is to overcome the disadvantages.

Indeed, unexpectedly and unexpectedly, using only inorganic compounds doped with halides in the form of salts can very efficiently reduce heavy metals present in the flue gas, particularly in the gaseous state, over a wide range of temperatures, and the preparation and application of such compounds I found it simple and not dangerous.

The effect of the composition according to the invention on the reduction rate of heavy metals was not particularly expected because the reduction performance of the doped inorganic compounds is much lower than that of the undoped inorganic compounds. Certain solid inorganic materials which do not have a significant capacity for heavy metal reduction in the undoped state, in particular, which do not have significant porosity, for example slaked lime, are reduced in heavy metal after being doped with halogenated salts according to the invention. It has a much higher heavy metal reduction capacity than many carbonaceous compounds that are best known for their adoption. In addition, solid inorganic materials, such as halosites, which already have a tendency to reduce heavy metals, in particular mercury, can be increased by a 10-fold, several-fold increase in heavy metal reduction capacity after being doped with halide salts according to the invention.

Inorganic compounds according to the invention in particular comprise inorganic supports in combination with halide dopants in salt form without any known capacity for heavy metal reduction.

Thus, the inorganic compound according to the present invention may be, for example, hydrated lime, dolomite, limestone and / or halosite.

“Inorganic compounds doped with halogenated salts” are from the group consisting of halosite, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, sodium carbonate, mixtures and derivatives thereof, the surfaces accessible to the flue gas being partially or completely covered with halogen salts It means the selected inorganic compound.

Gas-accessible surfaces include some or all of the inner surface of the partially porous particles as well as the outer surface of the particles that make up the inorganic solid.

In one advantageous embodiment, the halide salt is an inorganic halide salt, in order not to introduce additional carbonaceous compounds into the flue gas.

Inorganic compounds doped with halogenated salts comprise from 0.5 to 20% by weight, preferably from 1 to 15% by weight, in particular from 1.5 to 10% by weight, of halogenated salts, based on the weight of the composition according to the invention. Halogenated salts are alkali halides or alkaline earth halides, especially NaCl, NaBr, NaI, KCl, KBr, KI, CaCl ₂ , CaBr ₂ , CaI ₂ , MgCl ₂ , MgBr ₂ , MgI ₂ , or NH ₄ Cl, NH ₄ Br, NH ₄ I or a mixture thereof _,

Advantageously, the inorganic compound according to the invention is in powder form, ie the particle size essentially exceeds 1 μm and in most cases (greater than 90%) is smaller than 1 mm, ie has a d ₉₀ of less than 1 mm.

d ₉₀ means the extrapolated value of a particle size distribution curve in which 90% of the particles have a size less than this value.

Unexpectedly, it has been found that the inorganic compounds doped with these halogenated salts offer the possibility to reduce the heavy metals, particularly mercury, most particularly metallic mercury Hg ⁰ , in the gaseous state, in a very high efficiency in the flue gas.

Other embodiments of the products according to the invention are described in the appended claims.

The object of the invention is also a process for the preparation of the inorganic solid composition according to the invention. These methods are:

Supplying an inorganic compound selected from the group consisting of halosite, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, sodium carbonate, and mixtures and derivatives thereof,

Supplying a halogen flame, and

Contacting said inorganic compound with said halogenated salt to form an inorganic compound doped with said halogenated salt

Contains

Advantageously, the contact of the inorganic compound with the halogen salt is made while stirring.

As mentioned above, preferably in the process according to the invention, the inorganic solid material is selected from the group consisting of slaked lime, dolomite, limestone and / or halosite.

Preferably, the supplied inorganic compound has a humidity of 0.1 to 100 g / kg, advantageously 2 to 90 g / kg.

Advantageously, the contact is carried out at room temperature.

In a preferred embodiment of the process according to the invention, said halogenated salt is in liquid form in the aqueous phase.

In addition, the contacting step of the inorganic compound with the halogen salt is spraying the halogen salt on the inorganic compound, optionally with stirring.

In an alternative preferred embodiment of the process according to the invention, the contacting step of the inorganic compound with the halogen salt is a one or multiple soaking process, optionally with stirring, optionally an inorganic compound in the liquid halide salt. It is carried out with an intermediate step of drying.

Preferably, said liquid halide salt is an aqueous solution, said aqueous solution being 1% by weight to salt saturation of the solution, in particular 1 to 35% by weight, especially 5 to 27% by weight, preferably based on the total weight of the aqueous solution. Halogenated salt content of 10 to 27% by weight. Note that the low salt concentration in the solution makes the application of the mixture more difficult and also more expensive for subsequent drying. In addition, the concentration of the solution is limited by the solubility of the salt. The contact of the halide salt with the inorganic compound is carried out to promote a possible uniform distribution of the halide salt on the inner surface as well as the accessible outer surface of the inorganic compound.

Advantageously, the process according to the invention is preferably in view of obtaining a residual humidity (moisture) of less than 100 g / kg, advantageously less than 50 g / kg, preferably from 60 to doped inorganic compounds. Drying and / or deagglomerating the inorganic compound doped with a halogen salt according to the process conditions (ambient temperature, residence time ...) leading to temperatures of 200 ° C, in particular 75-170 ° C. do.

As mentioned above, preferably, in the process according to the invention, the halide salts are alkali halides, alkaline earth halides and the like, preferably NaCl, NaBr, NaI, KCl, KBr, KI, CaCl ₂ , CaBr ₂ , CaI ₂ , MgCl ₂ , MgBr ₂ , MgI ₂ , NH ₄ Cl, NH ₄ Br, NH ₄ I and mixtures thereof.

Other embodiments of the method according to the invention are described in the appended claims.

The present invention further provides the above-mentioned inorganic compounds for reducing the heavy metals present in the flue gas, in particular in the gaseous state, in particular mercury, most particularly metallic mercury Hg ⁰ , by contacting the flue gas with the solid inorganic composition described above. And the use of a mixture of said basic inorganic reagent and said solid inorganic composition for treating flue gas.

The doped inorganic compounds according to the invention are contacted in the form of mixtures with the flue gas to be treated and on their own or with a basic reagent generally used to reduce acid gases from the flue gas, such as other solid materials, in particular lime, etc. .

After all, the application of the solid inorganic composition according to the invention preferably requires only obtaining a dry product that is simple to use.

The use of the doped inorganic compounds according to the invention to reduce heavy metals is carried out at temperatures of 70 to 350 ° C., in particular 110 to 300 ° C., more preferably 120 to 250 ° C., preferably in the dry state. Includes contact. Working prospects, especially at or near 200 ° C. for contact, can be maintained at relatively constant temperatures throughout the process of treating flue gases, removing heavy metals and then removing nitrogen-containing compounds by catalysts. Successive cooling and heating steps may not be performed or may be limited.

Advantageously, the inorganic compounds according to the invention are used in powder form, ie the particle size is mostly (greater than 90%) smaller than 1 mm (less than 1 mm d ₉₀ ) and essentially greater than 1 μm. The inorganic compound is injected into the gas pipe by air pressure.

The use of inorganic compounds doped in accordance with the present invention to reduce heavy metals in flue gas can often be integrated into the complete treatment of the flue gas. This treatment involves removing the major acid contaminants by contacting the flue gas with a basic reagent. In general, the main acidic contaminants in flue gases include hydrochloric acid, hydrofluoric acid, sulfur oxides or additional nitrogen oxides, and their content in flue gas emissions prior to treatment is on the order of tens to hundreds of mg / Nm 3.

When the use of the doped inorganic compounds according to the invention to reduce heavy metals in the flue gas is incorporated into the complete treatment of the flue gas, the basic reagents, for example lime, and the doped inorganic compounds are individually or in the form of mixtures. Is applied. The latter is advantageous in terms of investment and plant space since the two steps can be performed simultaneously in the same place.

Other uses according to the invention are mentioned in the appended claims.

Other features, details, and advantages of the present invention will become more apparent from the following detailed description, with reference to the following examples in a non-limiting manner.

The present invention is explained in more detail by the following non-limiting examples.

Examples 1-9 and Comparative Examples are laboratory scale tests according to the experimental procedure below. About 100 mg of an inorganic compound doped with a halogen salt (Examples 1-9, the present invention) or an undoped inorganic compound (Comparative Example) is placed in the center of a cylindrical reactor having a length of 110 mm and an inner diameter of 10 mm. rock wool) to form a homogeneous layer. A nitrogen stream containing 600 μg / Nm 3 of metallic mercury (Hg ⁰ ) is flowed into the bed at a total flow rate of 2.8 10 ⁻⁶ Nm 3 / s. Mercury Instruments' VM-3000 detector can be used to measure metallic mercury levels at the outlet of the reactor. Before reaching the detector, the gas passes through a SnCl ₂ solution and is converted to metallic mercury, a possible fraction of mercury present in ionic form. In this way, the total amount of mercury is measured. With this device, the principle of breakthrough curves can be applied to evaluate the mercury reduction capacity by solids. Reduction doses are expressed as (μg Hg) / (g solid). Tables 1 and 2 summarize the manufacturing methods and mercury reduction performance for Examples 1-7 and Comparative Examples.

Comparative example

Commercially available halosite or lime is placed in the reactor described above. A breakthrough curve is obtained at a set temperature of 130 ° C. The mercury reduction doses of conventional halogenite and lime which are not doped in the above-described apparatus are 40 (μg Hg) / (g halosite) and 1 (μg Hg) / (g lime) respectively.

Example  One

According to the present invention, soaking of the halosite and lime similar to the comparative example is carried out. This immersion is performed by impregnating each of the halosite and lime in an aqueous solution, the aqueous solution having a KBr content of 10% by weight based on the weight of the aqueous solution. This doped wet halosite and wet lime are dried and deaggregated in an oven at 75 ° C. to reach residual moisture of less than 50 g / kg. The amount of KBr deposited on the halosite and lime after drying is 10% by weight, based on the weight of the composition according to the invention. The mercury reduction doses of halosite and lime doped with KBr according to the present invention obtained by working under the same operating conditions as the comparative example in the above-described apparatus were 486 (μg Hg) / (g-doped halosite) and 24 (μg Hg), respectively. ) / (g doped lime).

Table 1-Summary of Laboratory Tests-Lime Example Comparative example One additive
Initial solution
Doping
Humidity after Impregnation
Drying temperature
Impregnated additive level
Mercury Reduction (µgHg / g) none
-
-
-
-
-
One KBr
10%
Immersion
50%
75 ℃
10%
24

Example  2

Spraying of halosite similar to the comparative example is carried out according to the invention. The spraying is carried out using an aqueous solution, the aqueous solution having a KBr content of 27% by weight based on the weight of the aqueous solution. The solution is sprayed onto the halosite with mechanical stirring until 20% humidity is obtained. This doped wet halosite was dried in a 150 ° C. oven and deagglomerated to reach residual moisture of less than 50 g / kg. The amount of KBr deposited on the halosite after drying is 6% by weight based on the weight of the composition. The mercury reduction dose of this KBr-doped halosite is 198 (μg Hg) / (g doped halosite).

Example  3

The procedure of Example 2 is repeated except that a solution with 27 wt% MgCl ₂ based on the weight of the aqueous solution is used. Spray the solution onto the halosite with mechanical stirring until a humidity of 15% is obtained. The amount of MgCl ₂ deposited on the halosite after drying is 6% by weight based on the weight of the composition. The measured mercury reduction dose is 326 (μg Hg) / (g doped halosite).

Example  4

The procedure of Example 2 is repeated except that a solution having 27% by weight of MgBr ₂ based on the weight of the aqueous solution is used. Spray the solution onto the halosite with mechanical stirring until a humidity of 15% is obtained. The amount of MgBr ₂ deposited on the halosite after drying is 6% by weight based on the weight of the composition. The measured mercury reduction dose is 3140 (μg Hg) / (g doped halosite).

Example  5

The procedure of Example 2 is repeated except that a solution with 27 wt% CaCl ₂ based on the weight of the aqueous solution is used. Spray the solution onto the halosite with mechanical stirring until a humidity of 17% is obtained. The amount of CaCl ₂ deposited on the halosite after drying is 6% by weight based on the weight of the composition. The measured mercury reduction dose is 215 (μg Hg) / (g doped halosite).

Example  6

The procedure of Example 2 is repeated except that a solution with 27 wt% CaBr ₂ based on the weight of the aqueous solution is used. Spray the solution onto the halosite with mechanical stirring until a humidity of 15% is obtained. The amount of CaBr ₂ deposited on the halosite after drying is 6% by weight based on the weight of the composition. The measured mercury reduction dose is 447 (μg Hg) / (g doped halosite).

Example  7

The procedure of Example 2 is repeated except that a solution with 9 wt% NH ₄ I based on the weight of the aqueous solution is used. Spray the solution onto the halosite with mechanical stirring until a humidity of 16% is obtained. The amount of NH ₄ I deposited on the halosite after drying is 2% by weight, based on the weight of the composition. The measured mercury reduction dose is 1940 (μg Hg) / (g doped halosite).

Table 2-Summary of Laboratory Tests-Halloysite Example Comparative example One 2 3 4 5 6 7 additive
Initial solution
Doping
Humidity after Impregnation
Drying temperature
Impregnated additive level
Mercury Reduction (µgHg / g) none
-
-
-
-
-
40 KBr
10%
Immersion
50%
75 ℃
10%
486 KBr
27%
Spray
20%
150 ℃
6%
198 MgCl ₂
27%
Spray
15%
150 ℃
6%
326 MgBr ₂
27%
Spray
15%
150 ℃
6%
3140 CaCl ₂
27%
Spray
17%
150 ℃
6%
215 CaBr ₂
27%
Spray
15%
150 ℃
6.5%
447 NH ₄ I
9%
Spray
16%
150 ℃
2%
1940

Example  8-the effect of the concentration of the doping solution

Embodiment, repeat Example 2, compared by spraying the MgBr ₂ solution having a 5%, 9%, 27% , MgBr 2 concentration of 35% in order to obtain the deposition of the additive content of 1%, 2%, 6% and 10% Four halosite samples similar to the example are impregnated. The impregnated halosite is placed in a reactor maintained at a set temperature of 130 ° C. Under these test conditions, the mercury reduction doses are 509, 905, 3140 and 3980 (μg Hg) / (g halosite), respectively. Increasing the concentration of halides in the doped halosite results in a significant increase in mercury reduction.

Example  9: influence of reactor temperature

Example 2 is repeated using a 27% by weight solution of CaBr ₂ based on the weight of the aqueous solution. The amount of CaBr ₂ deposited on the halosite after drying is 1.2% by weight, based on the weight of the composition. Breakthrough curves are obtained at set temperatures of 130 ° C, 200 ° C, 250 ° C and 300 ° C.

The mercury reduction doses measured under these test conditions were 367, 829, 926 and 848 (μg Hg) / (g doped halosite), respectively. These results show the advantageous use of the doped compositions according to the invention especially at 200 to 300 ° C.

Example  10-industrial scale

According to the invention, the halosite similar to the comparative example is sprayed and doped in an industrial mixer. To this end, an aqueous solution having a KBr content of 25% by weight based on the weight of the aqueous solution is sprayed. The flow rate of the doped halosite with 18% humidity is 200 kg / h. The latter is deagglomerated and dried by a hot gas of about 400-450 ° C. in a cage grinder / dryer for a residence time until the gas leaves the grinder / dryer at about 150 ° C. A dried halosite according to the invention is obtained having 10 wt% KBr based on the weight of the composition.

The doped halosite thus obtained is used in a line for treating flue gas with a flow rate of about 150,000 Nm 3 / h resulting from the regeneration of nonferrous metals. Doped halosite is metered by screws and injected into the gas stream by air pressure in an amount of 60 kg / h at 170 ° C. and collected in a sleeve filter, in particular a sleeve filter with combustion dust.

The mercury concentration was measured by atomic absorption method (MERCEM from Sick-Maihak) upstream of the injection point of the doped halosite and downstream of the sleeve filter. The measured concentrations nominal to dry gas and referred to as 20% oxygen are as follows:

87 μg / Nm 3 upstream and

13 μg / Nm3 downstream. These results show an 85% mercury reduction rate.

Example  11-industrial scale

The doped halosite of Example 11 is used in a line that treats flue gas with a flow rate of about 20,000 Nm 3 / h resulting from regeneration of nonferrous metals. Doped halosite is metered by screw and injected by air pressure into the gas stream in an amount of 30 kg / h at 70 ° C. and then collected in a sleeve filter, in particular a sleeve filter with combustion dust.

Mercury concentrations were measured by atomic absorption method upstream of the injection point of the doped halosite and downstream of the sleeve filter. The measured mercury concentration nominally dry gas and referred to as 21% oxygen is as follows:

450 μg / Nm 3 upstream and

30 μg / Nm3 downstream. These results show a mercury reduction rate of 93%, below the effective emission limit of 50 μg / Nm3.

It is to be understood that the present invention is not limited to the above described embodiments and that various modifications may be made without departing from the scope of the appended claims.

Claims (19)

A composition for reducing heavy metals in a flue gas, comprising an inorganic compound, preferably an unfunctionalized inorganic compound, wherein the inorganic compound is doped with a halide salt, halloysite, calcium carbonate, A composition selected from the group consisting of magnesium carbonate, calcium hydroxide, magnesium hydroxide, sodium carbonate, and mixtures and derivatives thereof. The composition of claim 1, wherein the halogen salt is an inorganic halide salt. The composition of claim 1 or 2, wherein the inorganic compound is preferably selected from the group consisting of halosite, slaked lime, dolomite, limestone and mixtures thereof. 4. The halogen salt according to claim 1, wherein the halogenated salt is present at a dry weight in the range of 0.5 to 20% by weight, preferably 1 to 15% by weight, in particular 1.5 to 10% by weight, based on the weight of the composition. Composition. The halogenated salt according to claim 1, wherein the halogenated salt is preferably NaCl, NaBr, NaI, KCl, KBr, KI, CaCl ₂ , CaBr ₂ , CaI ₂ , MgCl ₂ , MgBr ₂ , MgI ₂ , Alkali halides, alkaline earth halides, etc. selected from the group consisting of NH ₄ Cl, NH ₄ Br, NH ₄ I and mixtures thereof. 6. The composition according to claim 1, wherein the inorganic compound is in powder form and has a d _{90 of} less than 1 mm and in particular a particle size of 1 μm to 1 mm. 7. Supplying an inorganic compound selected from the group consisting of halosite, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, sodium carbonate, and mixtures and derivatives thereof,
Supplying a halogen flame, and
Contacting said inorganic compound with said halogenated salt to form an inorganic compound doped with said halogenated salt
Including a method for producing a composition for reducing heavy minerals in the flue gas. 8. The method of claim 7, wherein the contact of the inorganic compound with the halogen salt is made while stirring. The method of claim 7 or 8, wherein the supplied inorganic compound has a humidity of 0.1 to 100 g / kg, advantageously 2 to 90 g / kg. The method of claim 7, wherein the contacting is performed at room temperature. The method according to any one of claims 7 to 10, wherein the halogenated salt is in liquid form in the aqueous phase. 12. The method of any of claims 7-11, wherein the contacting of the inorganic compound with a halogen salt sprays the halogen salt on the inorganic compound. The method of any one of claims 7 to 11, wherein the contacting of the inorganic compound with a halogen salt is soaking the inorganic compound in the liquid halide salt. The liquid according to claim 11, wherein the liquid halide salt is not an aqueous solution, and the solution is from 1% by weight to the salt saturation of the solution, in particular from 1 to 35% by weight, Preferably having a halogenated salt content of 5 to 27% by weight. The inorganic compound doped with the halogenated salt according to any one of claims 7 to 14, preferably dried and / or deagglomerated at a temperature of from 60 to 200 ° C, in particular from 75 to 170 ° C. Further comprising). The halogenated salt according to claim 7, wherein the halogenated salt is preferably NaCl, NaBr, NaI, KCl, KBr, KI, CaCl ₂ , CaBr ₂ , CaI ₂ , MgCl ₂ , MgBr ₂ , MgI ₂ , Alkali halides, alkaline earth halides, etc. selected from the group consisting of NH ₄ Cl, NH ₄ Br, NH ₄ I and mixtures thereof. Use of the composition according to any one of claims 1 to 6 for reducing heavy metals, in particular mercury, most particularly metallic mercury Hg ⁰ , in the flue gas. Use according to claim 17 in the form of a mixture with another solid material, in particular a basic reagent such as lime. Use according to claim 17 or 18, wherein the doped inorganic compound is contacted with the flue gas at a temperature in the range from 70 to 350 ° C, in particular from 110 to 300 ° C, preferably from 120 to 250 ° C.