RO130748B1 - Process of wet desulphurization of acid spent gases while recycling the suspension resulting therefrom - Google Patents

Abstract

The invention relates to a process for wet desulphurization of acid spent gases. According to the invention, the process consists in contacting the acid spent gases containing SOand/or other acid components with the aqueous suspension of desulphurization agents which contain 15...20% MgO, at a temperature of 40...90°C, where the molar ratios between the SOamount removed from the processed gases and the total amount of CaO and MgO supplied with the desulphurization agent suspension are of 1:1.05, to result in high purity gypsum and magnesium sulphate solution to be recycled as industrial-grade magnesium sulphate, magnesium hydroxide, magnesium oxide, magnesium carbonate and basic carbonate.

Description

The invention relates to a process for the wet desulfurization of waste gases charged with sulfur dioxide and other acidic components, of mineral or organic origin. The process consists in the suspension of the absorbent material in the technological water of the magnesitic limestone, dolomitic and brucitic limestone classes, dolomite, magnesite, brucite, olivine and serpentinite or their mixtures in micronized or non-synchronized state, followed by contacting the resulting suspension with charged gases composed of , until the total neutralization of them from gases, and the depletion of the neutralization capacity of the absorbent material, as well as of the subsequent processing of the reaction products in different technological phases, until obtaining salable products.

Numerous processes are known for the desulfurization of waste gases containing SO _X , NO _X and other mineral or organic acid components, based on absorption / adsorption processes, dry or wet, with chemical reaction, using, as desulfurizing agents, mineral materials. alkalines of the limestone class more or less pure, according to the patents US 3808321/1974, US 4552683/1985 and US 2006070561/2006.

The current processes for desulfurization of waste gases from fossil coal combustion in electricity production units through the wet process are based on the reaction: CaCO ₃ + SO ₂ + 1 / 2O ₂ + 2H ₂ O = CaSO ₄ · 2H ₂ O, which occurs in the liquid phase, after the SO ₂ absorption of gases and the forced oxidation of the sulfites initially formed, with the oxygen in the air being blown into the absorber.

Current processes for desulfurization of waste gases through the wet process consist of the oxidative absorption of SO ₂ in suspensions of finely chopped natural calcium carbonate (limestone), sprayed in multi-stage absorption, specially designed for this process, with and without recirculation of calcium carbonate suspensions. , with and without forced oxidation, with air, of the suspensions used, with and without the addition of additional additives for intensifying the three-phase mixing (gas-liquid-solid) and chemical reactions, as well as for finishing the crystallization of calcium sulphate as dihydrate, and achieving of the reasonable yields of SO ₂ removal, respectively, of the maximum yields of active CaO from limestone. Patent JP 3361775/2000 recommends cutting the limestone to dimensions of the order of 0.01 ... 0.10 mm, and a specific area of at least 30 m ² / g, and the patents US 4836991/1989 and US 5168065/1992 specify the principal technological parameters of the process, as well as the usual way of regulating and controlling these parameters.

Numerous embodiments of the production flow are known, according to the patents US 3966878/1976, US 4600570/1986, WO 9416797/1994, KR 20100138644/2009, CN 202844870/2012, CN 202724993/2012, CN 103446866/2013, US 8663585 / 2014, and several types of reactors in which SO ₂ uptake and oxidation of waste gases take place, according to GB patents 1410037/1972, UK 2149679/2000, CN 201313032/2008, JP 2009220021/2008, CN 201586442/2009, CN 101862587/2010, CN 101934195/2010, JP 2012020216/2010, CN 102225308/2011, JP 2012239958/2011, CN 103301727/2013, CN 203183915/2013, CN 103752164/2014.

Numerous processes are known to intensify all the physical and chemical processes involved in SO ₂ elimination technology from the flue gases resulting in the units of electricity production from fossil coal through the wet process. Of these, the most important are:

a) stabilization of the calcium carbonate suspension to ensure its homogeneity and fluidity, as well as to prevent foaming and crust formation on the flow paths and in the suspension dispersion devices in the gas flow;

b) introduction of synergistic agents for accelerating the mass transfer processes, accelerating the crystallization of calcium sulphate as a dihydrate, and improving its filterability, as well as for favoring the wetting and dissolution of the calcium carbonate particles, in order to obtain maximum yields for the use of limestone;

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c) introduction of oxidation agents to accelerate the oxidation of sulphates to sulphates in liquid phase 1, and to increase the overall speed of the desulfurization process, respectively, for reducing the SO ₂ content in the gases released into the atmosphere. 3

Patent CN 102773003/2012 describes a process for increasing the stability of the suspension by reducing its viscosity with a stabilizer consisting of 25 ... 45 parts of organic polycarboxylic acid and 10 ... 20 parts of metallic polyphosphate, and patent WO 2013082856 / 2012 proposes as dispersant a mixture of 15 ... 40% sodium formate (the dispersant itself) and 15 ... 40% 7 organic antifoam. The number of synergistic agents proposed is high and their composition is highly diversified. Among the inorganic synergistic agents may be mentioned: 9 sodium perborate (CN patent 102327737/2012) and sodium thiosulphate (US patent 4994246/1991). Their action consists in increasing the speed and the oxidation efficiency of the sulphites. The recommended 11 synergistic agents of an organic nature are: alkyl succinic esters coupled with organic humectants (patent TW 200944285/2009), organic acids resulting in the manufacture of cyclohexanone 13 (patent TW 243418/1995), organic acids and their salts (CN patent 102380301 / 2012), esters of alkyl sulfonic acids coupled with organic humectants (CN patent 101574615/2009), as well as 15 carboxylated and hydroxycarboxylated organic compounds (CN patent 102974209/2013). Their action is multiple: they increase the overall desulfurization yield, increase the yield of 17 transformations of the limestone, increase the oxidation rate of the sulphites, change the optimum pH of the main reaction, increase the wettability of the limestone and decrease the energy consumption. Joint action 19 of the organic and inorganic synergistic agents intensifies the expected effects. Among their complex formulations, can be mentioned: caproic acid, glutaric acid and polixiloxanes 21 coupled with magnesium chloride (CN patent 102000491/2010), adipic acid, its salts and organic surfactants coupled with salts of heavy metals (patentCN 102580514/2012 ), 23 citric acid, salicylic acid and polycarboxylic acids, coupled with oxides and salts of alkali metals (CN patent 102145252/2011), organic acids coupled with inorganic magnesium compounds (patent 25 CN 102814118/2012), organic acids and organic surfactants coupled with magnesium salts (patent CN103263842 / 2013), organic solvents coupled with magnesium and sodium salts 27 (CN patent 103263843/2013), organic amines coupled with magnesium and sodium salts (CN patent 103272472/2013), polyl acids icarboxy I here with high molecular weight, coupled with 29 inorganic salts (patent CN 102847429/2013), hydroxy-aromatic acids with high molecular weight, sodium benzoates and carboxometers il cellulose coupled with ferric oxide (CN patent 103752162/2014). 31

Their action extends from the intensification of the oxidation process and the intensification of mass transfer processes, to the increase of the overall efficiency, the prevention of inlay 33 equipment, the limitation of the secondary effects of impurities and the reduction of energy consumption. The catalysts introduced into the suspension of calcium carbonate to accelerate the oxidation of sulfites are manganese salts and oxides (CN 103446870/2013, CN 103752161/2014,

CN 103357263/2013), organic and inorganic chemical combinations or lanthanide 37 (CN 101954240/2011, CN 103191785/2013), metal oxides and, in particular, AI ₂ O ₃ and SiO ₂ (CN 102114385/2011, CN 102847428/2013 , CN 103446870/2013), and the organic and 39 inorganic salts containing the ammonium ion (CN 103433070/2013). The catalysts are accompanied by additives capable of supporting their homogenization in suspension, preventing foaming and accumulation of 41 active substances in the foam, respectively, to ensure the increased solubility of calcium carbonate.

The catalytic effect of oxidation is reflected in the increased oxidation rate of sulphites, the decrease of SO ₂ content in the gases discharged into the atmosphere, the increase of the overall desulfurization process efficiency, and the reduction of energy consumption. 45

The wet processes for eliminating SO ₂ from the waste gases, listed above, equally solve both the problem of identifying an economically reactive absorbent material 47 affordable and the achievement of an optimized level of performance against the need to lower SO ₂ concentrations in the processed gases up to limits accepted by the environmental protection rules 49. but the by-product, gypsum for industrial use, is a cheap product with little chance

RO 130748 Β1 to cover by exploitation the operating costs, and the less to amortize the initial investment, the improvements mentioned above; even if they can be accepted as viable technical solutions, they are unprofitable as they increase operating costs. In addition, the additional introduction of additives, to improve the technological performance of the process, can damage the quality of the gypsum and raise major problems of pollution of waste water.

The technical problem solved by the invention, by the process of wet desulfurization of acid waste gases and integrated technology of valorization of the suspension resulting after desulfurization, according to the invention, consists in the partial or total replacement of the limestone as a desulfurizing agent, with materials of the magnesite limestone classes. , dolomitic limestones and brucitic limestones, dolomite, magnesite, brucite, olivine and serpentinite, or their mixtures in micronized or non-micronized state, materials more reactive than limestone, which limit the production of gypsum and allow obtaining, as the second by-product, of magnesium sulphate as a solution convertible to magnesium sulphate for industrial use, crude and purified magnesium hydroxide, crude and purified magnesium oxide, crude and purified basic magnesium carbonate and carbonate, together with the conversion of the sulphate ion into salable products, such as ammonium sulphate, its potassium sulphate u, ultimately, calcium sulphate recovered in the form of gypsum for industrial use, as in the primary phase of desulfurization of waste gases containing SO ₂ , achieving significant reductions in raw materials and energy.

The process according to the invention solves this technical problem by providing for the replacement of the limestone suspension in a proportion of 5 ... 100% with the suspension of a mineral activated or not mechanically activated, with the average particle size between 0 and 100 pm, preferably smaller than 20 pm, belonging to the class of magnesium alkali compounds of the type oxides, hydroxides, chemically bonded or chemically bound to other chemical elements in the form of oxides, hydroxides, carbonates or silicas, single or double, hydrated or non-hydrated, having a content of at least 15 ... 20% MgO, of which at least 30% is in the form of Mg (OH) ₂ .

The process according to the invention consists in obtaining an aqueous suspension with a concentration of 20 ... 50% of an alkaline mineral, or of a mixture of micronized or non-synchronized alkaline minerals, having a particle size between 0 and 60 pm, preferably between 10 and 20 pm. , coming from the classes of natural minerals: magnesite limestone, dolomitic limestone and brucitic limestone, magnesite, brucite, olivine and serpentinite, with or without a preliminary enrichment, and contacting the suspension prepared with acid residual gases containing SO ₂ under similar conditions, but not identical, and using similar equipment, but not identical to those used in the wet desulphurization process with limestone suspensions.

The process according to the invention removes the disadvantages of the other variants of applying the wet process of acid desulfurization of waste gases, using the limestone suspension as a desulfurization agent, in that it changes the internal mechanism of the desulfurization process, following the introduction of the magnesium sulphate formation reaction. with a weight equivalent to that of CaSO formation and precipitation ₄ · 2H ₂ O, having the following consequences on the chemistry of the desulfurization process: increasing the concentration of the sulphite ion in the liquid phase, due to the higher solubility of magnesium sulphite, compared to the solubility of calcium sulphite, intensification the process of oxidation of the sulphites, due to the increase of their concentration in the liquid phase of the suspension, the increase of the acidity of the liquid phase, due to the higher solubility of magnesium sulphite, and, consequently, the increase of the solubility rate of calcium carbonate, and acceleration. error of the crystallization process of CaSO ₄ · 2H ₂ O under the higher supersaturations, generated by the intensification of the oxidation process of the sulphites, the increase of the intensity of the fragmentation process of the suspended solid particles, together with the increase of their specific surface, due to the dissolution of the magnesium component of the agent. desulfurization and, thus, the prevention of the formation of CaSO ₄ · 2H ₂ O crusts on the surface

RO 130748 Β1 to particles not reacted by CaCO ₃ , and accelerating the entire desulphurization process, reducing the amount of CO ₂ released per unit volume of the suspension, due to the presence of Mg (OH) ₂ in the desulphurizing agent, and thereby reducing the foaming capacity of the 3 suspension, increasing the density and viscosity of the liquid phase, and thereby increasing the stability of the suspension. This new desulfurization mechanism makes the use of synergistic agents, oxidizing agents or suspension stabilizers useless for accelerating the overall process. 7

The process according to the invention substantially modifies the internal mechanism of the global process of desulfurization of waste gases from the combustion processes of high sulfur coal 9, through the wet process, but does not change the general principles of the desulfurization technology, nor the systems for ensuring the excess. of available oxygen 11 for SO ₂ oxidation, or fluid recirculation systems in the technological process, and neither the system for controlling and regulating the technological parameters. 13

The process according to the invention benefits from the advantages induced by the change of the internal mechanism of the global process of desulfurization of waste gases from 15 coal burning processes with high sulfur content, through the wet process, and allows to achieve 93 ... 98% yields. in the process of eliminating SO ₂ from the processed gases, 17 and a yield of 95 ... 98% in the consumption of desulphurizing agent, under the conditions of use as a reference parameter of a molar ratio 1.00 / 1.05 between the amount of SO ₂ removed from the 19 gases processed, and the total amount of CaO and MgO fed with the suspension of the desulphurizing agent, at a temperature of 4O ... 9O ° C. 21

The process according to the invention allows the separation of the SO ₂ disposal streams from the waste gases, and the recovery of SO ₂ recovered in the form of industrial gypsum, from the flow of 23 magnesium sulphate solution processing and the valorisation of this product as industrial magnesium sulfate, crude and purified magnesium hydroxide, crude and purified magnesium oxide 25, crude and purified basic magnesium carbonate and carbonate, together with the conversion of the sulfate ion into salable products such as ammonium sulfate, potassium sulfate 27 or calcium sulphate, separated, by precipitation with hydrated lime in the form of gypsum for industrial use, next to magnesium hydroxide, from which it is separated by hydrocyclone, and then recycled 29 in the primary phase of desulfurization of waste gases containing SO ₂ . Moreover, in the case of the use of magnesium sulphate in the form of magnesium hydroxide and CaSO ₄ · 2H ₂ O, by 31 treating the solution of magnesium sulphate with hydrated lime, followed by the recirculation of gypsum and waste water in the SO ₂ disposal stream. waste gases, the process according to the invention allows the closure of a manufacturing cycle, with the full use of the products resulting from the desulfurization of the gases from the combustion of sulfur-containing coal. 35

The configuration of the two manufacturing flows is illustrated in the figure in which is presented the diagram of the integrated technology for desulfurization and capitalization of the corneal products resulted by processing the CaSO ₄ · 2H ₂ O suspension and the conversion of the magnesium sulphate formed by the solubilization of the magnesium from the limestones. magnesian. 39 In the technological scheme of the figure, the raw materials and auxiliaries are: technological water 1, magnesian limestone 2, thermocouple gases 3, air for oxidation 4 and non-ferrous lime 5. From the magnesian limestone and technological water, the absorbent suspension is prepared 6 , supplied in the desulphurisation phase of the technological process 7. The purified gases 43 in the desulphurisation phase 7 are released into the atmosphere, and the suspension of CaSO ₄ · 2H ₂ O, in the concentrated magnesium solution, accumulates in the collector. suspension 8, where 45 additional air is supplied for oxidation of SO ₃ ^(2_) to SO4 ⁽²⁾ . From the collector 8, part of the suspension of CaSO4 · 2H ₂ O in the concentrated magnesium solution is recirculated in the desulphurisation phase 7, and a suspension amount equivalent to the amount of magnesian limestone, fed as a suspension in the desulphurisation phase 7, is filtered for CaSO ₄ · 2H ₂ O. separation. 49

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The filtration operation takes place in three stages. In the first step (not shown in the diagram in the figure), most of the concentrated solution of MgSO ₄ is separated by hydrocyclone, and is sent to the collector of concentrated solution 11. Next, the thickened suspension of CaSO ₄ · 2H ₂ O is filtered. on an advanced precipitate wash filter, with recirculated technological water and fresh technological water, for the complete removal of magnesium sulfate from CaSO ₄ · 2H ₂ O. cake in the diagram shown, filtration I 9 is designated as the functional area of of the filter from which the concentrated solution of MgSO ₄ is collected, which is then sent to the concentrated solution collector 11. Filtration 1110 is designated as a functional area of the filter from which the washing water of CaSO ₄ · 2H ₂ O is collected, then recirculated, partially or total, together with the recirculated waters from the recirculated water collector 15, as lime hydration waters. The wet precipitate, separated and washed 23, is the finished product that can be used as industrial gypsum. Part of the concentrated solution of magnesium sulphate is caustified in the caustification phase 13 with the hydrated lime 12, in order to obtain Mg (OH) ₂ and MgO. The remainder of the concentrated magnesium sulfate solution is concentrated in the Concentration-Crystallization phase 16, until the optimum concentration for crystallization of MgSO ₄ · 7H ₂ O. The crystallized product is separated from the suspension by filtration and then dried, resulting in the commercial product MgSO ₄ · 7H ₂ O 18. Part of MgSO ₄ · 7H ₂ O is calcined to anhydrization 19, resulting in the commercial product anhydrous MgSO ₄ 20. The mother solution from crystallization of MgSO ₄ · 7H ₂ O 17 is recirculated to the Concentration-Crystallization plant. 16, and all the waste water collected on the production flows of anhydrous MgSO ₄ · 7H ₂ O and MgSO ₄ is sent in the suspension stream, from the caustification plant 13, to the Hidrocyclone I 14. The suspension resulting from the caustification MgSO ₄ 13 is thickened. in the hydrocyclone phase 114, and the waste water is sent to the recirculated water collector 15. In the hydrocyclone phase II 21, the thickened suspension in the hydro rocyclone I is fractionated in a suspension concentrated in Mg (OH) ₂ as a solid phase, and a suspension concentrated in CaSO ₄ · 2H ₂ O as a solid phase. In filtration phase III 22, CaSO4 · 2H ₂ separates. It can be used as a high quality industrial gypsum, and the waste water is sent to the recirculated water collector 15. The suspension concentrated in Mg (OH) ₂ is thickened in the hydrocyclonal phase III 24, and the thickener is centrifuged in step 25, to reduce the moisture content, and then calcined in phase 26, to obtain the commercial product MgO 27. The wastewater from hydrocyclonal phases III 24, centrifugation 25 and calcination 26 are sent to the recirculated water collector. 15. The MgSO ₄ solution processing technology is flexible and easily adaptable to changing ratios between the productions of the 3 kinds of magnesium compounds, resulting as marketable end products, when the magnesium content in the raw material varies within significant limits. Also, the technology can be adapted to manufacture other useful products containing SO ₄ ^(2_) or Mg ⁽²⁺⁾ , such as MgCO ₃ · 3H ₂ O, K ₂ SO ₄ , (NH ₄ ) ₂ SO ₄ , 4MgCO ₃ · Mg (OH) ₂ · '5H ₂ O, 4MgCO ₃ · Mg (OH) ₂ · 4H ₂ O, MgCO ₃ · Mg (OH) ₂ · 3H ₂ O etc.

The process according to the invention, by increasing the oxidation capacity of the active components of the suspension composition used, allows the partial elimination of NOx and mercury, with and without increasing the oxygen content in the flue gases, or increasing the oxygen / air flow in the suspension manifold. recirculated in the absorber.

The process according to the invention also allows the processing of other categories of acid waste gases containing SOx, NOx, HC1, HF, etc., and the identification of the processes for processing the residual solutions.

The process according to the invention has the following advantages:

- the increase of the productivity of the process, expressed by the consumption of desulfurizing agent per ton of SO ₂ eliminated from gases, due to the molecular mass difference between the fraction of CaO from the composition of the replaced desulfurizing agent, and the fraction of MgO or MgCO ₃ from alkaline agents containing magnesium, used as desulphurizing agents;

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- the decrease of the energy consumption, proportional to the decrease of the consumption of 1 desulfurization agent, since the energy consumed in the process depends exclusively on the flows of solid and liquid materials conveyed; 3

- increasing the yields in all the technological phases in which the desulphurizing agent is involved, due to the synergistic and oxidizing effect of the magnesium component in the position of the desulphurizing agent;

- the flexibility of the process, induced by the possibility of adjusting the ratio between the secondary products 7, and the variability of the conditions of integration of the technologies of conversion of magnesium sulphate into salable products; 9

- the easy adaptability and without high consumption of raw materials and energy, to the variations of SO ₂ concentrations in the waste gases, respectively, to the variation of the quality of the coal used in 11 units of electricity production.

Two examples illustrating the invention are given below. 13

Example 1

The laboratory experiment was performed under conditions similar to those existing in the absorber of the industrial gas desulphurization plant, in order to determine the performances of the wet desulphurization process with limestone filler, with a content of 92% CaCO ₃ or 17 51.5% CaO and 8% insoluble, and comparison of these performances with the performances of the process according to the invention. The experiment was performed on a sample 50 g filler type limestone, ground up to 19 at the average particle size of 30 µm, having the theoretical neutralization capacity of SO ₂ of 588.2 kg SO ₂ / t crude limestone or 24.41 g SO _2/50 g raw lime. The installation used was made up of an absorption column with a diameter of 10 cm, provided with a frit for the uniform distribution of gas in the filament-type limestone suspension, supplied with waste gas 23 directly taken from the gas inlet pipe in the industrial absorber, and with air taken from the atmosphere by a mini compressor. Both gases were passed through bubbling vessels 25 filled with water, to saturate them with water vapor, and to constantly maintain the amount of water in the limestone suspension. The flow rates of the two gases were 200 l / h, and 27 were chosen at the values indicated to conduct the experiment under hydrodynamic conditions similar to those of the industrial absorber, and to allow the complete oxidation of SO ₂ to SO ₃ . Thus, 29 the total flow of 400 l / h corresponds to a volumetric flow of gas of approximately 51 m ³ / m ² · h or a linear velocity of the gas through the limestone suspension of 0.014 m / s. The concentration of the limestone suspension was 30%, ie 50 g of limestone and 117 ml of water. The experiment started with the bubbling of the residual gases containing SO ₂ in the water from the bubble, to saturate it with SO ₂ . Then the air supply to the column was started, the water was introduced into the column, and the column supply was coupled with SO ₂ . The actual experiment started at 35 when the 50 g of limestone was introduced into the column, and the desulfurization time was started. During the experiment, the SO ₂ concentration in the waste gases was measured at regular intervals, and the SO ₂ concentration at the outlet of the desulfurization column, the pH and temperature of the suspension, as well as the total concentration of SO ₃ 39 (-2) and HSO ions ₃ (-1). The experiment ended when the SO ₂ concentration at the exit of the desulfurization column increased over 200 ppm. 41

The measurements made showed that:

a) the pH of the suspension varied during the experiment between 4.8 and 5.6; 43

b) the average temperature of the suspension was 45 ° C;

c) the total concentration of SO ₃ ⁽²⁾ and HSO3 ⁽¹⁾ ions varied between 350 and 450 mg SO2 / L; 45

d) The average SO ₂ concentration in the gases collected from the waste gas pipeline to the industrial absorber was 5600 mg / Nm ³ . 47

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The experiment was completed after 21.7 hours, when there was a concentration of

210 mg SO ₂ / Nm ³ . From the material balance it was found that from the waste gases 23.43 g of SO ₂ were extracted, ie the desulfurization yield was 23.43 / 24.41 x 100 = = 96.0%. Since the molar ratio CaO in limestone / SO ₂ in gas was 1/1, the yield efficiency of the limestone was the same.

Example 2

An identical experiment was performed with a sample of 50 g magnesite limestone having the composition: 35.3% CaO, 19.3% MgO (of which at least 30% is in the form of Mg (OH) ₂ ) and 5.9 % insoluble. The average particle size of 30 pm was magnesite, limestone and neutralization of the theoretical capacity of SO ₂ was 712.2 kg SO ₂ / t crude magnesite, limestone or 35.61 g SO _2/50 g of crude magnesite, limestone.

Measurements at the end of the experiment showed that:

a) The pH of the suspension varied during the experiment between 4.0 and 6.0;

b) the average temperature of the suspension was 47 ° C;

c) the total concentration of SO ₃ ^{( 2)} and HSO3 ^{( 1)} ions varied between 400 and 550 mg SO2 / L;

d) the average SO ₂ concentration in the gases collected from the waste gas pipeline to the industrial absorber was 5800 mg / Nm ³ .

The experiment was completed after 31.3 h, when a concentration of 210 mg SO ₂ / Nm ₃ was recorded. From the material balance it was found that 35.06 g of SO ₂ were extracted from the waste gas, that is the desulfurization yield was 35.06 / 35.61 x 100 = = 98.4%. As the molar ratio CaO in limestone / SO ₂ in gas was 1/1, the consumption yield of magnesitic limestone was the same.

From the results of the two experiments, one tonne of magnesitic limestone neutralizes 712.2 x 0.984 = 700.8 kg SO ₂ , and one tonne of limestone filler neutralizes 588.2 x 0.96 = 564.7 kg SO ₂ . The reduction of the physical consumption of desulfurization agent in the case of the use of magnesitic limestone is (700.8 - 564.7) / 700.8 x 100 = 19.4%. All energy consumption for all the technological phases of the process of desulfurization of waste gases will be reduced by 19.4%. The reactivity of the magnesitic limestone to the filler limestone is higher (98.4 - 96.0) / 98.4 x 100 = 2.4%, that is, under the conditions of a lower desulphurisation agent consumption of 19.4%, a desulphurisation yield of 2.4% can be achieved.

Claims (3)

1. A process of wet desulfurization of acid waste gases with 3 mineral alkaline agents, mechanically activated and inactivated, consisting of contacting acid waste gases, to eliminate SO ₂ with an aqueous suspension of an alkaline agent or a mixture of 5 alkaline agents, followed by collection, oxidation and thickening of the resulting suspension, filtration and washing of the solid component, partial or total recovery of the resulting mum solution of 7 at the separation of CaSO ₄ x H ₂ O, and its recirculation in the process, characterized by the removal of SO ₂ from the gases residual occurs by contacting the aqueous suspension with a concentration of 20 ... 50% of an alkaline mineral or a mixture of alkaline minerals, with or without preliminary enrichment, in micronized or non-micronized state, having a dimension 11 of of particles between 0 and 60 pm, preferably between 10 and 20 pm, and a content of at least 15 ... 20% MgO, of which at least 30% is in the form of Mg (OH) ₂ , with 13 acid residual gases containing SO ₂ at a temperature of 4O ... 9O ° C, using a molar ratio between the amount of SO ₂ removed from the processed gas and the quantity total CaO and MgO a- 15 with the suspension of the desulphurizing agent between 1.00: 1.00 and 1.00: 1.05. 2. A process for the wet desulfurization of acid waste gases, according to claim 17, characterized in that the alkaline minerals used to obtain the aqueous suspension are magnesitic, dolomitic or brucitic limestones, such as dolomite, magnesite, 19 brucite, olivine and serpentinite. 3. A process for the wet desulfurization of acid waste gas according to claim 21, characterized in that the products of the desulphurization reaction of crystallized calcium sulfate dihydrate, separable by filtration, and the magnesium sulphate solution can be subsequently used 23 to industrial gypsum, respectively, magnesium sulfate heptahydrate and magnesium oxide are obtained, and the sulphate ion can be converted into commercial products, such as 25 ammonium sulfate and potassium sulfate.