RO130748A0 - Process of wet desulphurization of acid spent gases and integrated technology for 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

PROCESS FOR WET DESULFURIZATION OF ACID RESIDUAL GASES AND INTEGRATED SUSPENSION VALUATION TECHNOLOGY RESULT

AFTER DESULFURIZATION

The invention relates to a process for the wet desulfurization of waste gases charged with sulfur dioxide and other acidic combinations of mineral or organic origin. The process consists in the suspension in the technological water of the absorbent material of the magnesite, dolomite and brucitic limestone classes, dolomite, magnesite, brucite, olivine and serpentine or their mixtures in micronized or non-synchronized state, followed by contacting the resulting suspension with the charged gases in the pollutants. until the total neutralization of the acidic components of the 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 the salable products.

Numerous processes for the desulfurization of waste gases containing SO _X , NO _X and other mineral or organic acid components are known, based on dry or wet processes of absorption / adsorption with chemical reaction, using as desalination agents alkaline mineral materials of limestone class. more or less pure, according to the patents US3808321 / 1974, US4552683 / 1985 and US2006070561 / 2006.

The current processes of desulfurization of waste gases from fossil coal combustion in the units of electricity production through the wet process are based on the reaction: CaCO ₃ + SO ₂ + 1/2 O ₂ + 2 H ₂ O = CaSO ₄ -2H ₂ O which occurs in the liquid phase after SO2 absorption of gases and forced oxidation of sulfites initially formed with oxygen from the air blown into the absorber.

Current processes for desulfurization of waste gases through the wet process consist of the oxidative absorption of SO2 in suspensions of finely chopped natural calcium carbonate (limestone), sprayed in multi-stage absorption specially designed for this process, with and without recirculating the suspensions of calcium carbonate, with and without the forced air oxidation 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 reasonable yields by removing it. SO2, respectively, of the MIR Group TimisaM® ^ A \

Z Z SC \ \ President, Irina Maricic;

gbvp-mir aron —-> —-. ./ \\ srl / 7

Λ 2 Ο 1 5 - - 000991 2 -02- 2015

maximum consumption yields of active CaO from limestone. Patent JP3361775 / 2000 recommends shredding of limestone to dimensions of the order of 0.01 -0.10 mm and a specific surface area of at least 30 m ² / g, and patents US4836991 / 1989 and US5168065 / 1992 specify the main technological parameters of the process, such as and the usual way of adjusting and controlling these parameters.

Numerous embodiments of the production flow are known, according to the patents US3966878 / 1976, US4600570 / 1986, WO9416797 / 1994, KR20100138644 / 2009,

CN202844870 / 2012, CN202724993 / 2012, CN103446866 / 2013, US8663585 / 2014 and several types of reactors in which SO2 uptake and oxidation of waste gases take place, according to patents GB1410037 / 1972, RU2149679 / 2000, CN201313032 / 2008, JP2009220021 / 2008 , CN201586442 / 2009, CN101862587 / 2010, CN101934195 / 2010,

JP2012020216 / 2010, CN102225308 / 2011, JP2012239958 / 2011, CN103301727 / 2013,

CN203183915 / 2013, CN103752164 / 2014.

Numerous processes are known to intensify all the physical and chemical processes involved in SO2 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 deposits in the gas flow; b) Introduction of synergistic agents to accelerate mass transfer processes, accelerate the crystallization of calcium sulphate as a dihydrate and improve its filterability, as well as to favor the wetting and dissolution of calcium carbonate particles in order to obtain maximum yields of limestone use; c) The introduction of oxidation agents to accelerate the oxidation of sulphites to sulphates in the liquid phase and to increase the overall speed of the desulfurization process, respectively, to decrease the SO2 content in the gases released into the atmosphere. Patent CN102773003 / 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 polycarboxylate and 10-20 parts of metallic polyphosphate, and patent WO 2013082856/2012 proposes a dispersant of 15 -40% sodium formate (the dispersant itself) and 15-40% organic antifoam. The number of synergistic agents proposed is high, and their composition is highly diversified. Among the inorganic synergistic agents

Mention may be made of: sodium perborate (patent CN102327737 / 2012) and sodium thiosulphate (patent US4994246 / 1991). Their action consists in increasing the speed and the oxidation efficiency of the sulfites. Recommended synergistic agents of organic nature are: alkylsuccinic esters coupled with organic humectants (patent TW200944285 / 2009), organic acids resulting in the manufacture of cyclohexanone (patent TW243418 / 1995), organic acids and their salts (patent CN102380301 / 2012). esters of alkyl sulfonic acids coupled with organic humectants (patent CN101574615 / 2009), as well as carboxylated and hydroxycarboxylated organic compounds (patent CN102974209 / 2013). Their action is multiple: they increase the overall desulfurization efficiency, they increase the transformation yield of the limestone, they increase the oxidation rate of the sulphites, they modify the pH-optimum of the main reaction, they increase the wettability of the limestone and decrease the energy consumption. The common action of the organic and inorganic synergistic agents intensifies the expected effects. Among their complex formulations can be mentioned: caproic acid, glutaric acid and polixiloxanes coupled with magnesium chloride (patent CN102000491 / 2010), adipic acid, its salts and organic surfactants coupled with salts of heavy metals (patent CN 102580514/2012), citric acid, salicylic acid and polycarboxylic acids coupled with oxides and salts of alkali metals (patent CN102145252 / 2011) organic acids coupled with inorganic magnesium compounds (patent CN 102814118/2012), organic acids and organic surfactants coupled with magnesium salts CN103263842 / 2013), organic solvents coupled with magnesium and sodium salts (patent CN103263843 / 2013), organic amines coupled with magnesium and sodium salts (patent CN103272472 / 2013), polycarboxylic acids with high molecular weight coupled with inorganic salts patent CN102847429 / 2013), high molecular weight hydroxy-aromatic acids, sodium benzoates and carboxomethyl cellulose coupled with ferric oxide (bre vet CN103752162 / 2014). Their action extends from the intensification of the oxidation process and the intensification of the mass transfer processes until the increase of the overall efficiency, the prevention of the inlay of the equipment, the limitation of the secondary effects of the impurities and the reduction of the energy consumption. The catalysts introduced in the suspension of calcium carbonate to accelerate the oxidation of sulphites are the salts and oxides of manganese (CN103446870 / 2013, CN103752161 / 2014, CN103357263 / 2013), the organic and inorganic chemical combinations and the lanthanides (CN101954240 / 2011, CN103191785 / 2013). and in particular AI2O3 and S1O2 (CN102114385 / 2011, CN102847428 / 2013, CN103446870 / 2013) and the organic and inorganic salts containing the ion

C \ - 2 o 1 5 - - 0 0 0 9 9 Î 2 -02- 2015 ammonium (CN103433070 / 2013). The catalysts are accompanied by additives capable of supporting their homogenization in suspension, preventing foaming and accumulation of active substances in the foam, respectively, to ensure the increased solubility of calcium carbonate. The effect of the oxidation catalysts is reflected in the increase of the sulphite oxidation rate, the decrease of the SO2 content in the gases discharged into the atmosphere, the increase of the global desulfurization process efficiency and the reduction of the energy consumption.

The wet processes for eliminating SO2 from the waste gases, listed above, also solve both the problem of identifying an economically reactive reagent absorbent material, as well as achieving an optimized level of performance against the need to lower SO2 concentrations in the processed gases to the accepted limits. environmental protection rules. However, the by-product, the gypsum for industrial use, is a cheap product with low chances of covering by exploiting the costs of operation and even less to amortize the initial investment, the improvements mentioned above, even if they can be accepted as viable technical solutions. , are unprofitable as operating expenses increase. In addition, the additional introduction of additives to improve the technological performance of the process can damage the quality of the gypsum and can lead to major problems of wastewater pollution.

The technical problem solved by the invention of a process of wet desulfurization of acid waste gases and an 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 and brucitic limestones, dolomite, magnesite, brucite, olivine and serpentine or their mixtures in micronized or non-micronized state, materials more reactive than limestone, which limit the production of gypsum and allow the obtaining, as the second by-product, of magnesium sulfate. in the form of a convertible solution into magnesium sulfate 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 , potassium sulphate or, ultimately, sulfur the calcium layer recovered in the form of gypsum for industrial use, as in the primary phase of desulfurization of waste gases with SO2 contents, achieving significant reductions in raw materials and energy.

MIR Timjsoaca Foundation

President, Z - / _ X

Irina MaricicfâÎiigiP-MIR j

^ - 2 0 1 5 - 0 0 0 9 9 ί 2 -02- 2015

The process according to the invention solves this technical problem by that it provides 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, or at least 20pm at best. , belonging to the class of alkali magnesium compounds of the type oxides, hydroxides, carbonates or chemically bound or other chemical elements in the form of oxides, hydroxides, carbonates or silicates, 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 the preparation of 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, or better between 10 and 20 pm, coming from the classes of natural minerals: magnesitic limestone, dolomitic limestone and brucitic limestone, magnesite, brucite, olivine and serpentine with or without a preliminary enrichment and contacting the suspension prepared with the gases of acid waste gases with SO2 content under similar but not identical conditions 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 for acid desulfurization of waste gases, using the limestone suspension as desulfurization agent, by which it changes the internal mechanism of the desulfurization process, following the introduction of the magnesium sulfate formation reaction. with a weight equivalent to that of CaSO4-2H2O formation and precipitation, having the following consequences on the chemistry of the desulfurization process: increasing the concentration of sulphite ion in the liquid phase due to the higher solubility of magnesium sulfite compared to the solubility of calcium sulphite, intensifying the oxidation process 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 thereby the speed of solubilization of calcium carbonate and the acceleration of the crystallization process. CaSO4-2H2O under the higher supersaturations generated the intensification of the sulphite oxidation process, the increase of the intensity of the fragmentation process of the solid particles in suspension accompanied by the increase of their specific surface due to the dissolution of the magnesium component of the desulfurization agent and thus the prevention of the formation of Ca4 at the surface of the particles not reacted by CaCCh and accelerating the whole process

MIR Timiso Foundation;

President,. Irina Marieîca

SC

MitaRÎJPJÎή (χ- 2 β 1 5 - - 00099I 2 -02- 2015 desulfurization, reducing the amount of CO2 released per unit volume of suspension due to the presence of Mg (OH) 2 in the desulfurizing agent and thus reducing the foaming capacity of the suspension , increasing the density and viscosity of the liquid phase and thereby increasing the suspension stability.This new desulfurization mechanism makes it unnecessary to use synergistic agents, oxidizing agents or suspension stabilizers to accelerate the overall process.

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 through the wet process, but does not change the general principles of the desulfurization technology nor the systems for ensuring the excess oxygen available. for the oxidation of SO2 or the fluid recirculation systems in the technological process and neither the system of control and regulation of the technological parameters.

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 the combustion processes of high sulfur coal through the wet process and allows to achieve 93-98% yields in the process of SO2 elimination. from the processed gases and a 95-98% yield in the consumption of desulphurizing agent, under the conditions of use as reference parameter of a molar ratio 1.00 / 1.05 between the quantity of SO2 removed from the processed gases and the total amount of CaO and MgO fed with the suspension of the desulphurizing agent at a temperature of 40-90 ° C.

The process according to the invention allows the separation of the SO2 elimination flows from the waste gases and the recovery of SO2 recovered in the form of industrial gypsum from the processing flow of the magnesium sulphate solution and of the use of this product as the magnesium sulfate for use. industrial, crude and purified magnesium hydroxide, crude and purified magnesium oxide, crude and purified basic magnesium carbonate and carbonate, together with the conversion of sulphate ion into salable products, such as ammonium sulphate, potassium sulphate or calcium sulphate separated by precipitation with hydrated lime in the form of gypsum for industrial use together with magnesium hydroxide, which is separated by hydrocyclone and then recirculated in the primary phase of desulfurization of waste gases with SO2 contents. Moreover, in the case of the use of magnesium sulphate in the form of magnesium hydroxide and CaSO4-2H2O by treating the solution of magnesium sulphate with hydrated lime, followed by the recirculation of gypsum and

MIR Timiso Foundation ^ rSipDA / ŞX

President, Irina Maricica

^ -2015-- 000991 2 -02- 2015 wastewater in the SO ₂ waste stream, 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. The configuration of the two manufacturing flows is illustrated in figure 1, in which is presented the diagram of the integrated technology of desulfurization and of valorisation of the commercial 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 magnesian limestones. . In the technological scheme of figure 1, the raw materials and auxiliaries are: technological water (1), magnesian limestone (2), gas from the power plant (3), air for oxidation (4), and non-hydrated lime (5). From the magnesian limestone and the technological water, the absorbent suspension (6) fed in the desulphurization phase of the technological process (7) is prepared. The purified gases in the desulphurisation phase (7) are released into the atmosphere, and the CaSO ₄ .2H ₂ O suspension in the concentrated magnesium solution is accumulated in the suspension manifold (8), where additional air is supplied for SO3 oxidation (2-). SO ₄ (2-). From the collector (8), part of the suspension of CaSO ₄ -2H ₂ O in the concentrated magnesium solution is recycled in the desulfurization phase (7), and a suspension amount equivalent to the amount of magnesium limestone fed as a suspension in the desulfurization phase ( 7) is filtered to separate CaSO ₄ -2H ₂ O. The filtration operation takes place in three steps. In the first step (not shown in the diagram in figure 1), most of the concentrated solution of MgSO ₄ is separated by hydrocyclone and is sent to the concentrated solution collector (11). Further, the thickened suspension of CaSO ₄ -2H ₂ O is filtered on a filter with advanced washing of the precipitate with recirculated technological water and fresh technological water for the complete removal of magnesium sulphate from the CaSO ₄ -2H ₂ O. cake. Figure 1, filtration I (9) is designated as the functional area of the filter from which the concentrated solution of MgSO ₄ is collected, which is then sent to the concentrated solution collector (11). Filtration II (10) is designated as the functional area of the filter from which the waste water of CaSO ₄ -2H ₂ O is collected, then recirculated, partially or totally, together with the recirculated waters from the recirculated water collector (15), as water for hydration of lime. The separated and washed wet precipitate (23) is the finished product that can be used as industrial gypsum. Part of the concentrated magnesium sulfate solution is caustified in the caustification phase (13) with hydrated lime (12), in order to obtain Mg (OH) ₂ and MgO. The rest of the concentrated solution of magnesium sulfate is

^ -2015-- 000991 2 -02- 2015 concentrated in the Concentration - Crystallization (16) phase until the optimum concentration for crystallization of MgSO4-7H ₂ O is reached. The crystallized product is separated from the suspension by filtration and then dried, resulting in the commercial product MgSO4 -7H ₂ O (18). Part of the moist MgSO4-7H ₂ is calcined to anhydrization (19), resulting in the commercial product anhydrous MgSO 4 (20). The mum solution from the crystallization of MgSO4-7H ₂ O (17) is recirculated to the Concentration - Crystallization plant (16), and all the waste water collected on the manufacturing flows of MgSO4-7H ₂ O and anhydrous MgSCU is sent to the suspension stream. at the caustification facility (13) towards Hidrocyclone I (14). The suspension resulting from the caustification of MgSO ₄ (13) is thickened in the hydrocyclone phase I (14), and the waste water is sent to the recirculated water collector (15). In hydrocyclone phase II (21), the thickened suspension in hydrocylon I is fractionated into a suspension concentrated in Mg (OH) ₂ as a solid phase and a suspension concentrated in CaSO4-2H ₂ O as a solid phase. In the Filtration phase 3 (22), CaSO4'2H ₂ separates. It can be used as a high quality industrial gypsum, and the waste water is sent to the recycled water collector (15). The suspension concentrated in Mg (OH) ₂ is thickened in hydrocyclone phase III (24), and the thickener is centrifuged in phase (25) to reduce the moisture content and then calcined in phase (26) to obtain the commercial MgO product (27). . Waste water from hydrocyclonal phases III (24), centrifugation (25) and calcination (26) are sent to the recirculated water collector (15). The technology for processing solutions concentrated by MgSCh is flexible and easily adaptable to the changes of ratios between the productions of the 3 types of magnesium compounds resulting as marketable finished products, when the magnesium content in the raw material varies within significant limits. Also, the technology can be adapted to manufacture other useful products with SO4 (2-) or Mg (2+) contents, such as MgCO ₃ '3H ₂ O, K2SO4, (NFL ^ SC ^, 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 ΝΟχ and mercury, with and without increasing the oxygen content in the flue gases or increasing the oxygen / air flow in the recirculated suspension manifold. 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 identifying the processes for processing the residual solutions.

-2015-- 00099ί 2 -02- 2015

The process according to the invention has the following advantages:

- increasing the productivity of the process expressed by the consumption of desulphurizing agent per ton of SO2 eliminated from gas, due to the difference in molecular mass between the CaO fraction from the composition of the replaced desulphurizing agent and the fraction of MgO or MgCC> 3 from the alkaline agents containing magnesium content as desulphurizing agents;

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

- 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 of the desulphurizing agent composition;

- the flexibility of the process induced by the possibility of adjusting the ratio between by-products and the variability of the conditions of integration of the technologies for the conversion of magnesium sulfate into salable products;

- easy adaptability and without high consumption of raw materials and energy to the variations of SO2 concentrations in the waste gases, respectively, to the variation of the quality of the coal used in the units of electricity production.

Two examples illustrating the invention are given below:

Example 1. The laboratory experiment was performed under conditions similar to those existing in the industrial gas desulphurization plant absorber, in order to determine the performance of the wet desulphurization process with limestone filler with a content of 92% CaCCE or 51.5% CaO and 8 % insoluble and comparing these performances with the performance of the process, according to the invention. The experiment was excised on a sample of 50 g filler type limestone, milled to the average particle size of 30 µm, having the theoretical neutralization capacity of SO2 of 588.2 kg SO2 / 1 crude limestone or 24.41 g SO2 / 50 g rough limestone. The installation used was made up of an absorption column with a diameter of 10 cm, provided with irritation for the uniform distribution of the gas in the suspension of filler type limestone, fed with waste gases taken directly from the gas pipeline in the industrial absorber and with air. taken from the atmosphere by a mini compressor. Both gases were passed through bubbling vessels filled with water to saturate them with water vapor and to maintain the constant amount of water in the limestone suspension. The flow rates of the two gases were 200 1 / h. debits

ν 2 0 1 5 - - 0 0 0 9 9 1 2 -02- 2015 the two gases 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 at SO3. Thus, the total flow of 400 1 / h corresponds to a volumetric flow of gas of approximately 51 m ³ / m ² -h or to a linear gas velocity 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 SO2 in the water from the bubble to saturate it with SO2. Then, the air supply was started in the column, the water was introduced into the column and the column supply was coupled with SO2. The experiment itself began when the 50 g of limestone was introduced into the column and the timing of the desulfurization time began. During the experiment, the SO2 concentration in the waste gases and the SO2 concentration at the exit from the desulphurization column, the pH and the temperature of the suspension, as well as the total concentration of SO3 (-2) and HSO3 (-1) ions were measured at regular intervals. The experiment ended when the SO2 concentration at the exit from the desulfurization column increased over 200 ppm. The measurements made showed that: a) the pH of the suspension varied during the experiment between 4.8 and 5.6; b) the average temperature of the suspension was 45 ° C c) the total concentration of SO3 (-2) and HSO3 (-1) ions varied between 350 and 450 mg SO2 / L; d) The average SO2 concentration in the gases collected from the waste gas pipeline to the industrial absorber was 5600 mg / Nm. The experiment was completed after 21.7 hours, when a concentration of 210 mg SO2 / Nm ³ was recorded. From the material balance it was found that from the waste gases 23.43 g of SO2 were extracted, that is 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 magnesitic 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 magnesite, limestone was 30, and the theoretical capacity to neutralize the SO ₂ was 712.2 kg SO _2/1 crude magnesite, limestone and 35.61 g SO _2/50 g of crude magnesite, limestone. The measurements made 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 SO3 (-2) and HSO3 (-1) ions varied between 400 and 550 mg SO ₂ / L; d) the average SO ₂ concentration in the gases collected from the waste gas pipeline at a) mg / Nm ³ .

^ - “Eundatia MIR Timisoara aricaica Miron

Λ - 2 0 1 5 - - 0 0 0 9 9 I 2 -12- 201!

The experiment was completed after 31.3 hours, when a concentration of 210 mg SO ₂ / Nm ³ was recorded. From the balance of materials 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 it follows that: a) one ton of magnesitic limestone neutralizes 712.2 x 0.984 = 700.8 kg SO ₂ , and one ton of filler limestone neutralizes 588.2 x 0.96 = 564.7 kg SO ₂ . The reduction of the physical consumption of desulfurizing agent in 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%. can achieve a desulphurisation yield of 2.4% higher.

Claims (5)

1. Wet desulphurization process of acid waste gases and integrated technology for valorizing the suspension resulting after desulphurisation, characterized in that the removal of SO2 from the processed gases occurs after contacting the aqueous suspension with the concentration of 20-50% of an alkaline mineral or a mixture of alkaline minerals, from the magnesitic limestone, dolomitic and brucitic limestone classes, dolomite, magnesite, brucite, olivine and serpentine or mixtures thereof with or without preliminary enrichment, in micronized or non-micronized state, having particle size between 0 and 60 μιη, or better between 10 and 20 pm and a continuum of at least 15-20% MgO, of which at least 30% is in the form of Mg (OH) 2, with acidic residual gases containing SO2 at a temperature of 4090 ° C, under similar conditions, but not identical and using similar equipment, but not identical to those used in the wet desulphurization process with limestone suspensions and leads to a reduction of 15-20% of the consumption of desulphurizing agent and energy compared to the wet desulphurization process with limestone suspensions, to 93-98% yields in the process of eliminating SO2 from the processed gases and to yields of 95-98% in the consumption of desulphurizing agent, under the conditions of use as a reference parameter of a molar ratio between 1.00 / 1.00 and 1.00 / 1.05 between the quantity of SO2 eliminated from the processed gases and the quantity total CaO and MgO fed with the suspension of the desulphurizing agent. 2. A process for the wet desulfurization of acid waste gases and an integrated suspension recovery technology after desulfurization, according to claim 1, characterized in that the desulfurization reaction products are calcium sulfate dihydrate calcium separable by filtration and the magnesium sulfate solution which can be used after separation. of calcium sulphate dihydrate, and the flow of waste gas processing and recovery of SO2 recovered in the form of gypsum for industrial use is separated from the processing flow of the magnesium sulphate solution and of the use of this product in the form of magnesium sulfate. for industrial use, crude and purified magnesium hydroxide, crude and purified magnesium oxide, crude and purified basic magnesium carbonate and carbonate, in conjunction with the conversion of sulphate ion into commercial products, such as ammonium sulphate and potassium sulphate, or in calcium sulphate separated by precipitation with hydrated lime in the form of plaster s for industrial use next to magnesium hydroxide, which is separated by hydrochloric acid ^{1 1} \] Î! 4 ^ TEtindatia MIR Timișoara Maricica Miron 2 Ο 1 5 - - 0 0 0 9 9 1 2 -02- 2015 desulfurization of waste gases with SO ₂ contents, thus closing a complete manufacturing cycle with the full use of the products resulting from desulfurization of the gases from the combustion of coal containing sulfur. 3. Wet desulfurization process of acid waste gases and integrated technology of recovery of the resulting suspension after desulfurization, according to claim 1, characterized in that the waste gas processing and SO ₂ recovery flow recovered in the form of gypsum for industrial use and of the flux of processing of the magnesium sulphate solution and of valorisation of this product in the form of commercial products are integrated in a flexible and adjustable technology of all the major fluctuations of the concentration of SO ₂ in the waste gases, as well as the significant variations of the concentration CaO and MgO in magnesitic limestones. 4. A process for the wet desulfurization of acid waste gases and an integrated technology for utilizing the resulting suspension after desulfurization, according to claim 1, characterized in that the introduction of the desulfurizing agent with a content of at least 15-20% MgO, of which at least 30% it is found in the form of Mg (OH) ₂ , having a higher reactivity and a synergistic and additional oxidizing effect, changes the internal mechanism of the desulfatization process and determines: a) the increase of the sulfite ion concentration in the liquid phase due to the higher solubility of the sulfite; magnesium compared to the solubility of calcium sulphite; b) intensification of the oxidation process of the sulphites due to the increase of their concentration in the liquid phase of the suspension; c) increasing the acidity of the liquid phase due to the higher solubility of magnesium sulphite and thereby increasing the solubility rate of calcium carbonate and accelerating the crystallization process of CaSO4-2H ₂ O under the higher supersaturations generated by the intensification of the sulfite oxidation process; d) increasing the mass of the liquid phase in the suspension resulting from the desulfatization process and thereby improving the purity and filterability of precipitated gypsum; e) increasing the intensity of the fragmentation process of the solid particles in suspension accompanied by the increase of their specific surface due to the dissolution of the magnesium component of the desulphurization agent and thereby preventing the formation of CaSC> 4-2H ₂ O crusts on the surface of the particles not reacted by the CaCCL and accelerating the whole desulfurization process; f) reducing the amount of CO ₂ released on the suspension volume unit due to the presence of Mg (OH) ₂ in the desulfurizing agent and thereby reducing the foaming capacity of the suspension; g) increasing the density and viscosity this reduces the foaming capacity of the suspension; g) increase in density and viscosity 2 015 - - 0 0 0 9 9 1 2 -02-2015 the liquid phase and thereby increasing the stability of the suspension, making it unnecessary to use synergistic agents, oxidizing agents or suspension stabilizers in order to control and optimize the main parameters of the desulfurization process. 5. Wet desulphurization process of acid waste gases and integrated technology for valorizing the suspension resulting after desulphurisation, according to claim 1, characterized in that the reduction of the amount of CO2 released per unit volume of suspension due to the presence of Mg (OH) 2 in the agent desulfurization and the use of magnesium in the form of salable products diminishes the impact of the desulfurization process on the environment by reducing the total CO ₂ emission per ton of SO ₂ eliminated from the waste gases and the negative effect of magnesium on the quality of the waste water discharged from the process in the case of gypsum processing. for its use, or from the exfiltrates in the dump, if the wet plaster is not used.