A method for producing sulfuric acid from pyrite concentrate

Abstract

The application provides a method for preparing sulfuric acid from pyrite concentrate powder and belongs to the technical field of resource utilization. The method comprises the following steps: (1) crushing and screening pyrite concentrate powder raw materials to obtain fine pyrite concentrate powder; (2) introducing air into a fluidized roasting furnace, suspending and roasting the fine pyrite concentrate powder in the furnace, cooling the outlet furnace gas by heat absorption, further water-moistening the residue after roasting of the fluidized roasting furnace and slag dust generated in the production process after water cooling, and then transporting the residue and the slag dust to obtain roasted sand; (3) performing dust removal, mist removal, further cooling and drying treatment on the outlet furnace gas in the step (2) to obtain SO2-containing furnace gas, spraying sulfuric acid on the SO2-containing furnace gas after air supplement, cooling, and then storing liquid into a finished product storage tank and performing drying treatment on gas; and (4) performing catalytic oxidation and heat exchange treatment on the dried gas, absorbing SO3 in the furnace gas by using concentrated sulfuric acid, performing hydrogen peroxide treatment on tail gas, and then performing mist removal and standard discharge. The method has the advantages of simple production process, environmental protection in the production process and improved resource utilization rate.

Description

Technical Field

[0001] This invention relates to the field of resource utilization technology, specifically to a method for preparing sulfuric acid from pyrite concentrate powder. Background Technology

[0002] Cyanide tailings are industrial waste from gold mining companies. Their active ingredient is FeS2, a major component of pyrite. For many years, due to the low FeS2 content (only about 50%) in cyanide tailings, they have been mainly used by sulfuric acid production companies to produce sulfuric acid. The resulting sulfuric acid slag has a low iron content, and some of it is used as filler in cement production, while some is randomly stockpiled, resulting in the waste of iron resources and environmental pollution.

[0003] The FeS2 content in the cyanide tailings of gold mining enterprises is increased to approximately 90%. After full utilization of sulfur, iron is enriched to form iron concentrate, thus achieving comprehensive utilization of both sulfur and iron resources while effectively protecting the environment. The entire production process involves raw material pretreatment, raw material pulping, flotation reagent addition, flotation enrichment, and solid-liquid separation, producing pyrite concentrate powder with a sulfur content of approximately 48% and an FeS2 content of approximately 90%. Pyrite concentrate is the main raw material for producing super iron concentrate. Using pyrite concentrate to produce sulfuric acid not only yields high purity but also produces roasted iron ore with a high iron content, achieving efficient resource utilization.

[0004] However, existing technologies for preparing sulfuric acid from pyrite concentrate have the following shortcomings: Traditional sulfuric acid production catalysts are mainly based on the V₂O₅-K₂SO₄ / SiO₂ system, which suffers from low specific surface area (typically << 200 m² / g), small pore volume, and easy sintering and agglomeration of active components. Furthermore, traditional catalysts exhibit defects such as insufficient exposure of active sites and high mass transfer resistance during SO₂ catalytic oxidation, resulting in low SO₂ conversion rates. Simultaneously, the catalyst and products are difficult to separate rapidly after the reaction, leading to complex recovery processes and increased operating costs. The intrinsic activity of boron nitride-based catalytic materials is also limited. Summary of the Invention

[0005] The purpose of this invention is to propose a method for preparing sulfuric acid from pyrite concentrate powder. By constructing a highly efficient catalyst and combining it with a deep purification process for tail gas through hydrogen peroxide oxidation and demisting, this method solves the technical problems of catalyst deactivation due to arsenic poisoning, insufficient exposure of active sites, difficulties in separation and recovery, and excessive acid mist emissions in the tail gas during the sulfuric acid production process from pyrite concentrate powder. This method achieves a sulfur combustion rate >99.6%, a total SO2 conversion rate >99.9%, and tail gas acid mist <5 mg / Nm³. 3 Highly efficient resource utilization and ultra-low emissions.

[0006] The technical solution of this invention is implemented as follows: This invention provides a method for preparing sulfuric acid from pyrite concentrate powder, comprising the following steps: (1) The pyrite concentrate raw material is crushed and sieved to obtain fine pyrite concentrate powder; (2) Air is introduced into the fluidized bed roasting furnace, and the sulfur concentrate fine powder in step (1) is suspended and roasted in the furnace. The excess heat is absorbed by the cooling water in the form of steam. The outlet furnace gas is cooled by heat absorption, and the generated medium-pressure superheated steam is used to generate electricity for the steam turbine generator set. The residue after the fluidized bed roasting furnace and the slag and dust generated during the production process are cooled by water and further humidified by water before being transported out to obtain roasted sand. (3) The furnace gas exiting in step (2) is subjected to dust removal, demisting, further cooling and drying to obtain SO2-containing furnace gas. After replenishing air, sulfuric acid is sprayed, cooled, and the liquid enters the finished product storage tank. The gas is then dried. (4) The gas dried in step (3) is treated by catalytic oxidation and heat exchange, and SO3 in the furnace gas is absorbed by concentrated sulfuric acid. The tail gas is treated by hydrogen peroxide oxidation and demisting before being discharged in compliance with standards.

[0007] As a further improvement of the present invention, the mesh number of the sieve used in step (1) is 100-300 mesh.

[0008] As a further improvement of the present invention, the roasting temperature in step (2) is 850-900°C, and the cooling water is cooling circulating water.

[0009] As a further improvement of the present invention, the acid mist content of the exhaust gas emitted in step (4) is less than 5 mg / Nm³. 3 .

[0010] As a further improvement of the present invention, the catalyst used in step (4) for catalytic oxidation is prepared by the following method: S1. Preparation of porous SiO2 nanospheres: Alkyl ester of orthosilicate was added to ethanol, water and a pore-forming agent were added, the pH value of the solution was adjusted, the reaction was heated and stirred, centrifuged, washed, dried and calcined to obtain porous SiO2 nanospheres; S2. Modification: Porous SiO2 nanospheres were added to ethanol, a silane coupling agent was added, the mixture was heated and stirred to react, filtered, washed, and dried to obtain modified porous SiO2 nanospheres; S3. Loading: Dissolve potassium hydroxide and vanadium pentoxide in water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution, add lanthanum nitrate, sulfur and modified porous SiO2 nanospheres, heat and stir to react, filter, wash, dry and calcine to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres. S4. Preparation of magnetic iron oxide microparticle deposition: Ferric chloride and ferrous chloride were dissolved in water, and under inert gas protection, La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The pH of the solution was adjusted, the reaction was heated and stirred, filtered, washed, dried, and calcined to obtain magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres. S5. Formation of wrinkled heterojunctions: Boron nitride nanosheets and cerium nitrate were added to a mixed solution of ethanol and ethylene glycol, and magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The mixture was stirred and mixed evenly, followed by hydrothermal reaction, spray drying, and calcination to obtain the catalyst.

[0011] Preparation of the catalyst of this invention: Using porous, high-specific-surface-area nano-silica spheres as a support significantly increases the amount of subsequent catalyst material loaded and provides more active sites. Simultaneously, it provides a high-strength support, preventing catalyst structural collapse. Modification with an amino-containing silane coupling agent facilitates the adsorption of V₂O₅ loading, while appropriate La₂O₃ doping improves the pore size distribution and active component distribution of the catalyst, thereby increasing the utilization rate of the internal surface and allowing more vanadium species to be distributed in pentavalent form on the support surface. This provides more active material for the catalytic process and enhances the catalytic activity of the vanadium catalyst.

[0012] Ferromagnetic modification and deposition of iron oxide improves the separability of the catalyst, enabling rapid separation and recovery through an external magnetic field, thus reducing industrial operating costs. At the same time, the iron oxide portion also enhances the catalyst activity.

[0013] While hexagonal boron nitride (h-BN) possesses excellent thermal stability (>900°C in air) and a graphene-like layered structure, its high surface chemical inertness, scarcity of intrinsic active sites, and weak adsorption capacity of reactants (SO2 / O2) due to the polarity of the BN bonds result in low catalytic activation efficiency, limiting its application in high-temperature oxidation reactions. This invention introduces cerium dioxide (CeO2) as the active structural unit, utilizing its reversible Ce... 3+ / Ce 4+ Redox cycles and abundant surface oxygen vacancies significantly enhance the adsorption and dissociation capabilities of reactant molecules on the catalyst surface. By coupling CeO2 nanocrystals with boron nitride nanosheets, a synergistic effect of oxygen vacancy-interfacial polarization is constructed, promoting rapid migration of lattice oxygen and conversion of reaction intermediates, thereby strengthening the catalytic efficiency of the main active phase, V2O5. Furthermore, lanthanum oxide can capture gaseous As2O3, protecting the active sites of V2O5.

[0014] During spray drying, the solvent evaporates rapidly, causing the droplets to shrink in volume and forming wrinkled microspheres. This further increases the specific surface area of ​​the catalyst, thereby greatly increasing the contact area between the catalyst and the reactant SO2 and enhancing the catalytic activity.

[0015] As a further improvement of the present invention, the alkyl orthosilicate in step S1 is methyl orthosilicate or ethyl orthosilicate, the mass ratio of the alkyl orthosilicate, ethanol, water and porogen is 10-12:150-180:10-15:0.5-1, the porogen is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride, the pH of the solution is adjusted to 9-11, and the temperature of the heating and stirring reaction is 40-50°C for 8-12 hours.

[0016] As a further improvement of the present invention, the mass ratio of the porous SiO2 nanospheres to the silane coupling agent in step S2 is 100:2-3, the silane coupling agent is selected from at least one of KH550, KH602, and KH792, and the heating and stirring reaction temperature is 45-55℃ and the time is 2-4h.

[0017] As a further improvement of the present invention, the mass ratio of potassium hydroxide, vanadium pentoxide, lanthanum nitrate, sulfur and modified porous SiO2 nanospheres in step S3 is 1-1.2:1.2-1.4:0.1-0.15:0.5-1:2-4, the pH value of the solution is adjusted to 2-3, the temperature of the heating and stirring reaction is 30-40℃, and the time is 2-4h.

[0018] As a further improvement of the present invention, the mass ratio of ferric chloride, ferrous chloride and La2O3-doped V2O5-supported porous SiO2 nanospheres in step S4 is 3.24:1.26:8-10, the pH value of the solution is adjusted to 10-11, the temperature of the heating and stirring reaction is 85-95℃, and the time is 3-5h.

[0019] As a further improvement of the present invention, in step S5, the mass ratio of boron nitride nanosheets, cerium nitrate, and magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres is 2-3:0.3-0.5:10-12, the volume ratio of ethanol to ethylene glycol in the ethanol and ethylene glycol mixed solution is 2-4:1, and the hydrothermal reaction temperature is 175-185℃, and the time is 0.5-1.5h.

[0020] The present invention has the following beneficial effects: 1. This invention uses pyrite concentrate powder to produce sulfur dioxide flue gas and roasted sand after high-temperature roasting in a fluidized bed furnace. The iron content of the roasted sand is greater than 60%. After further purification, high-purity iron is obtained for further resource utilization. This simplifies the sulfuric acid production process, greatly improves the utilization rate of waste heat and other energy during the production process, and produces sulfuric acid with high purity. Moreover, the production process is environmentally friendly and improves the resource utilization rate of waste.

[0021] 2. This invention uses catalytic oxidation to convert SO2 into SO3. The catalyst of this invention has a high specific surface area, high catalytic efficiency and stability, magnetic field responsiveness, is easy to separate and regenerate, can be reused multiple times, reduces costs, is not easily poisoned, and has a long lifespan.

[0022] 3. The production process of this invention adopts a combined tail gas treatment process of furnace dust purification, furnace gas drying, catalytic conversion absorption, and hydrogen peroxide oxidation demisting, which simplifies the sulfuric acid production steps. After the tail gas is treated by hydrogen peroxide oxidation, SO2 is efficiently oxidized into sulfuric acid for recycling, and acid mist is deeply removed by a high-efficiency demister. The acid mist content of the emitted tail gas is low, and the SO2 emission concentration is far below the national standard limit. The production process meets environmental protection standards and has no secondary pollution.

[0023] 4. In this invention, excess heat from the fluidized bed roasting furnace is absorbed in the form of steam via cooling circulating water. The resulting medium-pressure superheated steam is used to power a steam turbine generator set, achieving efficient recovery and cascade utilization of waste heat. Compared with traditional processes, this significantly improves the utilization rate of waste heat and other energy sources during production, and reduces energy consumption and production costs per unit product.

[0024] 5. This invention organically integrates the crushing and screening of pyrite concentrate powder, fluidized bed roasting, furnace gas purification and drying, catalytic conversion and absorption, and tail gas treatment, simplifying the complex multi-stage process of traditional sulfuric acid production. The high activity, high stability, and easy separation and recovery characteristics of the catalyst further reduce catalyst consumption and replacement costs, resulting in a significant reduction in overall production costs. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The magnetization curve of the catalyst prepared in Example 1 of this invention.

[0027] Figure 2 The XRD pattern is shown for the catalyst prepared in Example 1 of this invention. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Preparation Example 1: Catalyst The preparation method is as follows: S1. Preparation of porous SiO2 nanospheres: 10g of methyl orthosilicate was added to 150g of ethanol, 10g of water and 0.5g of cetyltrimethylammonium bromide were added, the pH of the solution was adjusted to 9, heated to 40℃, stirred for 8h, centrifuged, washed, dried and calcined at 500℃ for 2h to obtain porous SiO2 nanospheres. S2. Modification: 10g of porous SiO2 nanospheres were added to 200mL of ethanol, 0.2g of silane coupling agent KH550 was added, the mixture was heated to 45℃, stirred for 2h, filtered, washed and dried to obtain modified porous SiO2 nanospheres. S3. Loading: Dissolve 1g potassium hydroxide and 1.2g vanadium pentoxide in 300mL of water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution to 2, add 0.1g lanthanum nitrate, 0.5g sulfur and 2g modified porous SiO2 nanospheres, heat to 30℃, stir and react for 4h, filter, wash, dry, calcine at 550℃ for 3h to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres; S4. Preparation of magnetic iron oxide microparticle deposition: 3.24 g of ferric chloride and 1.26 g of ferrous chloride were dissolved in 300 mL of water. Under nitrogen protection, 8 g of La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The pH of the solution was adjusted to 10, heated to 85 °C, stirred for 3 h, filtered, washed, dried, and calcined at 500 °C for 2 h to obtain magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres. S5. Formation of wrinkled heterostructures: 2g of boron nitride nanosheets and 0.3g of cerium nitrate were added to 100mL of a mixed solution of ethanol and ethylene glycol, wherein the volume ratio of ethanol to ethylene glycol in the mixed solution was 2:1. 10g of magnetic La₂O₃-doped V₂O₅-supported porous SiO₂ nanospheres were added, and the mixture was stirred until homogeneous. The mixture was then subjected to hydrothermal reaction at 175℃ for 1.5h, spray-dried, and calcined at 440℃ for 4h to obtain the catalyst. Figure 1 The magnetization curve of the prepared catalyst is shown in the figure. As can be seen from the figure, the saturation magnetization is 30.2 emu / g. Figure 2 The image shows the XRD pattern of the prepared catalyst. As can be seen from the image, the catalyst is a complex composite containing multiple crystalline and amorphous phases.

[0030] Preparation Example 2: Catalyst The preparation method is as follows: S1. Preparation of porous SiO2 nanospheres: 12g of tetraethyl orthosilicate was added to 180g of ethanol, 15g of water and 1g of hexadecyltrimethylammonium chloride were added, the pH of the solution was adjusted to 11, heated to 50℃, stirred for 12h, centrifuged, washed, dried and calcined at 500℃ for 2h to obtain porous SiO2 nanospheres. S2. Modification: 10g of porous SiO2 nanospheres were added to 200mL of ethanol, 0.3g of silane coupling agent KH792 was added, the mixture was heated to 55℃, stirred for 4h, filtered, washed and dried to obtain modified porous SiO2 nanospheres. S3. Loading: Dissolve 1.2g potassium hydroxide and 1.4g vanadium pentoxide in 300mL of water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution to 3, add 0.15g lanthanum nitrate, 1g sulfur and 4g modified porous SiO2 nanospheres, heat to 40℃, stir for 2h, filter, wash, dry, calcine at 550℃ for 3h to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres; S4. Preparation of magnetic iron oxide microparticle deposition: 3.24 g of ferric chloride and 1.26 g of ferrous chloride were dissolved in 300 mL of water. Under nitrogen protection, 10 g of La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The pH of the solution was adjusted to 11, heated to 95 °C, stirred for 5 h, filtered, washed, dried, and calcined at 500 °C for 2 h to obtain magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres. S5. Formation of wrinkled heterostructures: 3g of boron nitride nanosheets and 0.5g of cerium nitrate were added to 100mL of a mixed solution of ethanol and ethylene glycol, wherein the volume ratio of ethanol to ethylene glycol in the mixed solution was 4:1. 12g of magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres were added, stirred and mixed evenly, and hydrothermally reacted at 185℃ for 1.5h. After spray drying, the mixture was calcined at 440℃ for 4h to obtain the catalyst.

[0031] Preparation Example 3 Catalyst The preparation method is as follows: S1. Preparation of porous SiO2 nanospheres: 11g of tetraethyl orthosilicate was added to 165g of ethanol, 12g of water and 0.7g of cetyltrimethylammonium bromide were added, the pH of the solution was adjusted to 10, heated to 45℃, stirred for 10h, centrifuged, washed, dried and calcined at 500℃ for 2h to obtain porous SiO2 nanospheres. S2. Modification: 10g of porous SiO2 nanospheres were added to 200mL of ethanol, 0.25g of silane coupling agent KH602 was added, the mixture was heated to 50℃, stirred for 3h, filtered, washed and dried to obtain modified porous SiO2 nanospheres. S3. Loading: Dissolve 1.1g potassium hydroxide and 1.3g vanadium pentoxide in 300mL of water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution to 2.5, add 0.12g lanthanum nitrate, 0.7g sulfur and 3g modified porous SiO2 nanospheres, heat to 35℃, stir for 3h, filter, wash, dry, calcine at 550℃ for 3h to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres; S4. Preparation of magnetic iron oxide microparticle deposition: 3.24 g of ferric chloride and 1.26 g of ferrous chloride were dissolved in 300 mL of water. Under nitrogen protection, 9 g of La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The pH of the solution was adjusted to 10.5, heated to 90 °C, stirred for 4 h, filtered, washed, dried, and calcined at 500 °C for 2 h to obtain magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres. S5. Formation of wrinkled heterostructures: 2.5g of boron nitride nanosheets and 0.4g of cerium nitrate were added to 100mL of a mixed solution of ethanol and ethylene glycol, wherein the volume ratio of ethanol to ethylene glycol in the mixed solution was 3:1. 11g of magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres were added, and the mixture was stirred and mixed evenly. The mixture was then subjected to hydrothermal reaction at 180℃ for 1h, spray-dried, and calcined at 440℃ for 4h to obtain the catalyst.

[0032] Comparative Preparation Example 1 The only difference from Preparation Example 3 is that lanthanum nitrate was not added in step S3.

[0033] The preparation method is as follows: S1. Preparation of porous SiO2 nanospheres: 11g of tetraethyl orthosilicate was added to 165g of ethanol, 12g of water and 0.7g of cetyltrimethylammonium bromide were added, the pH of the solution was adjusted to 10, heated to 45℃, stirred for 10h, centrifuged, washed, dried and calcined at 500℃ for 2h to obtain porous SiO2 nanospheres. S2. Modification: 10g of porous SiO2 nanospheres were added to 200mL of ethanol, 0.25g of silane coupling agent KH602 was added, the mixture was heated to 50℃, stirred for 3h, filtered, washed and dried to obtain modified porous SiO2 nanospheres. S3. V2O5 loading: Dissolve 1.1g potassium hydroxide and 1.3g vanadium pentoxide in 300mL of water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution to 2.5, add 0.7g sulfur and 3g modified porous SiO2 nanospheres, heat to 35℃, stir and react for 3h, filter, wash, dry, calcine at 550℃ for 3h to obtain V2O5 loaded porous SiO2 nanospheres; S4. Preparation of magnetic iron oxide microparticle deposition: 3.24 g of ferric chloride and 1.26 g of ferrous chloride were dissolved in 300 mL of water. Under nitrogen protection, 9 g of V2O5-supported porous SiO2 nanospheres were added, the pH of the solution was adjusted to 10.5, heated to 90 °C, stirred for 4 h, filtered, washed, dried, and calcined at 500 °C for 2 h to obtain magnetic V2O5-supported porous SiO2 nanospheres; S5. Formation of wrinkled heterostructures: 2.5g of boron nitride nanosheets and 0.4g of cerium nitrate were added to 100mL of a mixed solution of ethanol and ethylene glycol, wherein the volume ratio of ethanol to ethylene glycol in the mixed solution was 3:1. 11g of magnetic V2O5-supported porous SiO2 nanospheres were added, and the mixture was stirred and mixed evenly. The mixture was then subjected to hydrothermal reaction at 180℃ for 1h, spray-dried, and calcined at 440℃ for 4h to obtain the catalyst.

[0034] Comparative Preparation Example 2 The only difference from preparation example 3 is that step S4 was not performed.

[0035] The preparation method is as follows: S1. Preparation of porous SiO2 nanospheres: 11g of tetraethyl orthosilicate was added to 165g of ethanol, 12g of water and 0.7g of cetyltrimethylammonium bromide were added, the pH of the solution was adjusted to 10, heated to 45℃, stirred for 10h, centrifuged, washed, dried and calcined at 500℃ for 2h to obtain porous SiO2 nanospheres. S2. Modification: 10g of porous SiO2 nanospheres were added to 200mL of ethanol, 0.25g of silane coupling agent KH602 was added, the mixture was heated to 50℃, stirred for 3h, filtered, washed and dried to obtain modified porous SiO2 nanospheres. S3. Loading: Dissolve 1.1g potassium hydroxide and 1.3g vanadium pentoxide in 300mL of water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution to 2.5, add 0.12g lanthanum nitrate, 0.7g sulfur and 3g modified porous SiO2 nanospheres, heat to 35℃, stir for 3h, filter, wash, dry, calcine at 550℃ for 3h to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres; S4. Formation of wrinkled heterostructures: 2.5g of boron nitride nanosheets and 0.4g of cerium nitrate were added to 100mL of a mixed solution of ethanol and ethylene glycol, wherein the volume ratio of ethanol to ethylene glycol in the mixed solution was 3:1. 11g of La2O3-doped V2O5-supported porous SiO2 nanospheres were added, and the mixture was stirred and mixed evenly. The mixture was then subjected to hydrothermal reaction at 180℃ for 1h, spray-dried, and calcined at 440℃ for 4h to obtain the catalyst.

[0036] Comparative preparation example 3 The only difference from preparation example 3 is that vacuum drying at 105°C for 4 hours was performed in step S5.

[0037] The preparation method is as follows: S1. Preparation of porous SiO2 nanospheres: 11g of tetraethyl orthosilicate was added to 165g of ethanol, 12g of water and 0.7g of cetyltrimethylammonium bromide were added, the pH of the solution was adjusted to 10, heated to 45℃, stirred for 10h, centrifuged, washed, dried and calcined at 500℃ for 2h to obtain porous SiO2 nanospheres. S2. Modification: 10g of porous SiO2 nanospheres were added to 200mL of ethanol, 0.25g of silane coupling agent KH602 was added, the mixture was heated to 50℃, stirred for 3h, filtered, washed and dried to obtain modified porous SiO2 nanospheres. S3. Loading: Dissolve 1.1g potassium hydroxide and 1.3g vanadium pentoxide in 300mL of water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution to 2.5, add 0.12g lanthanum nitrate, 0.7g sulfur and 3g modified porous SiO2 nanospheres, heat to 35℃, stir for 3h, filter, wash, dry, calcine at 550℃ for 3h to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres; S4. Preparation of magnetic iron oxide microparticle deposition: 3.24 g of ferric chloride and 1.26 g of ferrous chloride were dissolved in 300 mL of water. Under nitrogen protection, 9 g of La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The pH of the solution was adjusted to 10.5, heated to 90 °C, stirred for 4 h, filtered, washed, dried, and calcined at 500 °C for 2 h to obtain magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres. S5. Formation of wrinkled heterostructures: 2.5g of boron nitride nanosheets and 0.4g of cerium nitrate were added to 100mL of a mixed solution of ethanol and ethylene glycol, wherein the volume ratio of ethanol to ethylene glycol in the mixed solution was 3:1. 11g of magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres were added, and the mixture was stirred and mixed evenly. The mixture was then subjected to hydrothermal reaction at 180℃ for 1h, filtered, washed, vacuum dried at 105℃ for 4h, and calcined at 440℃ for 4h to obtain the catalyst.

[0038] Comparative preparation example 4 The only difference from Preparation Example 3 is that cerium nitrate was not added in step S5.

[0039] The preparation method is as follows: S1. Preparation of porous SiO2 nanospheres: 11g of tetraethyl orthosilicate was added to 165g of ethanol, 12g of water and 0.7g of cetyltrimethylammonium bromide were added, the pH of the solution was adjusted to 10, heated to 45℃, stirred for 10h, centrifuged, washed, dried and calcined at 500℃ for 2h to obtain porous SiO2 nanospheres. S2. Modification: 10g of porous SiO2 nanospheres were added to 200mL of ethanol, 0.25g of silane coupling agent KH602 was added, the mixture was heated to 50℃, stirred for 3h, filtered, washed and dried to obtain modified porous SiO2 nanospheres. S3. Loading: Dissolve 1.1g potassium hydroxide and 1.3g vanadium pentoxide in 300mL of water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution to 2.5, add 0.12g lanthanum nitrate, 0.7g sulfur and 3g modified porous SiO2 nanospheres, heat to 35℃, stir for 3h, filter, wash, dry, calcine at 550℃ for 3h to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres; S4. Preparation of magnetic iron oxide microparticle deposition: 3.24 g of ferric chloride and 1.26 g of ferrous chloride were dissolved in 300 mL of water. Under nitrogen protection, 9 g of La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The pH of the solution was adjusted to 10.5, heated to 90 °C, stirred for 4 h, filtered, washed, dried, and calcined at 500 °C for 2 h to obtain magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres. S5. Formation of wrinkled heterojunctions: 2.9 g of boron nitride was added to 100 mL of a mixed solution of ethanol and ethylene glycol, wherein the volume ratio of ethanol to ethylene glycol in the mixed solution was 3:1. 11 g of magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres were added, stirred and mixed evenly, and hydrothermally reacted at 180 °C for 1 h. After spray drying, the mixture was calcined at 440 °C for 4 h to obtain the catalyst.

[0040] Comparative preparation example 5 The only difference from preparation example 3 is that step S5 was not performed.

[0041] The preparation method is as follows: S1. Preparation of porous SiO2 nanospheres: 11g of tetraethyl orthosilicate was added to 165g of ethanol, 12g of water and 0.7g of cetyltrimethylammonium bromide were added, the pH of the solution was adjusted to 10, heated to 45℃, stirred for 10h, centrifuged, washed, dried and calcined at 500℃ for 2h to obtain porous SiO2 nanospheres. S2. Modification: 10g of porous SiO2 nanospheres were added to 200mL of ethanol, 0.25g of silane coupling agent KH602 was added, the mixture was heated to 50℃, stirred for 3h, filtered, washed and dried to obtain modified porous SiO2 nanospheres. S3. Loading: Dissolve 1.1g potassium hydroxide and 1.3g vanadium pentoxide in 300mL of water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution to 2.5, add 0.12g lanthanum nitrate, 0.7g sulfur and 3g modified porous SiO2 nanospheres, heat to 35℃, stir for 3h, filter, wash, dry, calcine at 550℃ for 3h to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres; S4. Preparation of magnetic iron oxide microparticle deposition: 3.24 g of ferric chloride and 1.26 g of ferrous chloride were dissolved in 300 mL of water. Under nitrogen protection, 9 g of La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The pH of the solution was adjusted to 10.5, heated to 90 °C, stirred for 4 h, filtered, washed, dried, and calcined at 500 °C for 2 h to obtain magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres, which are the catalyst.

[0042] Test Example 1 The specific surface area and total pore volume of the catalysts prepared in Examples 1-3 and Comparative Examples 1-5 were determined using a 3-FLEX 3500 multi-station high-throughput gas adsorption analyzer. Compressive strength was tested using an LJ 5000 compression testing machine with a range of 0-5000 N. The results are shown in Table 1.

[0043] Table 1

[0044] As can be seen from the table above, the catalysts prepared in Examples 1-3 of the present invention have high specific surface area and pore volume, and high compressive strength.

[0045] Example 1 This embodiment provides a method for preparing sulfuric acid from pyrite concentrate powder. It includes the following steps: (1) The pyrite concentrate raw material is crushed and passed through a 100-mesh sieve to obtain fine pyrite concentrate powder; (2) Air is introduced into the fluidized bed roasting furnace, and the sulfur concentrate fine powder in step (1) is suspended and roasted in the furnace at a roasting temperature of 850°C. Excess heat is absorbed by cooling circulating water in the form of steam. The outlet furnace gas is cooled by heat absorption, and the generated medium-pressure superheated steam is used to generate electricity for the steam turbine generator set. The residue after roasting in the fluidized bed roasting furnace and the slag and dust generated during the production process are cooled by water and further humidified by water before being transported out to obtain roasted sand. (3) The furnace gas exiting in step (2) is subjected to dust removal, demisting, further cooling and drying to obtain SO2-containing furnace gas. After replenishing air, sulfuric acid is sprayed, cooled, and the liquid enters the finished product storage tank. The gas is then dried. (4) The dried gas in step (3) is catalytically oxidized using the catalyst prepared in Example 1, and then subjected to heat exchange treatment. Concentrated sulfuric acid is used to absorb SO3 from the furnace gas. The tail gas is then oxidized with hydrogen peroxide and demisted before being discharged in compliance with emission standards. The acid mist content of the emitted tail gas is less than 5 mg / Nm³. 3 .

[0046] Example 2 This embodiment provides a method for preparing sulfuric acid from pyrite concentrate powder. It includes the following steps: (1) The pyrite concentrate raw material is crushed and passed through a 300-mesh sieve to obtain fine pyrite concentrate powder; (2) Air is introduced into the fluidized bed roasting furnace, and the sulfur concentrate fine powder in step (1) is suspended and roasted in the furnace at a roasting temperature of 900°C. Excess heat is absorbed by cooling circulating water in the form of steam. The outlet furnace gas is cooled by heat absorption, and the generated medium-pressure superheated steam is used to generate electricity for the steam turbine generator set. The residue after roasting in the fluidized bed roasting furnace and the slag and dust generated during the production process are cooled by water and further humidified by water before being transported out to obtain roasted sand. (3) The furnace gas exiting in step (2) is subjected to dust removal, demisting, further cooling and drying to obtain SO2-containing furnace gas. After replenishing air, sulfuric acid is sprayed, cooled, and the liquid enters the finished product storage tank. The gas is then dried. (4) The dried gas in step (3) is catalytically oxidized using the catalyst prepared in Example 1, and then subjected to heat exchange treatment. Concentrated sulfuric acid is used to absorb SO3 from the furnace gas. The tail gas is then oxidized with hydrogen peroxide and demisted before being discharged in compliance with emission standards. The acid mist content of the emitted tail gas is less than 5 mg / Nm³. 3 .

[0047] Example 3 This embodiment provides a method for preparing sulfuric acid from pyrite concentrate powder. It includes the following steps: (1) The pyrite concentrate raw material is crushed and passed through a 200-mesh sieve to obtain fine pyrite concentrate powder; (2) Air is introduced into the fluidized bed roasting furnace, and the sulfur concentrate fine powder in step (1) is suspended and roasted in the furnace at a roasting temperature of 880°C. Excess heat is absorbed by cooling circulating water in the form of steam. The outlet furnace gas is cooled by heat absorption, and the generated medium-pressure superheated steam is used to generate electricity for the steam turbine generator set. The residue after roasting in the fluidized bed roasting furnace and the slag and dust generated during the production process are cooled by water and further humidified by water before being transported out to obtain roasted sand. (3) The furnace gas exiting in step (2) is subjected to dust removal, demisting, further cooling and drying to obtain SO2-containing furnace gas. After replenishing air, sulfuric acid is sprayed, cooled, and the liquid enters the finished product storage tank. The gas is then dried. (4) The dried gas in step (3) is catalytically oxidized using the catalyst prepared in Example 1, and then subjected to heat exchange treatment. Concentrated sulfuric acid is used to absorb SO3 from the furnace gas. The tail gas is then oxidized with hydrogen peroxide and demisted before being discharged in compliance with emission standards. The acid mist content of the emitted tail gas is less than 5 mg / Nm³. 3 .

[0048] Comparative Examples 1-5 The only difference from Example 1 is that the catalyst was prepared by Comparative Preparation Examples 1-5.

[0049] Test Example 1 The methods in Examples 1-3 and Comparative Examples 1-5 were compared and evaluated, and the results are shown in Table 2.

[0050] Table 2

[0051] Note: The initial SO2 conversion rate and the total SO2 conversion rate are both calculated during the conversion process.

[0052] As can be seen from the table above, the methods in Examples 1-3 of this invention have a high sulfur calcination rate and a high SO2 conversion rate.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing sulfuric acid from pyrite concentrate powder, characterized in that, Includes the following steps: (1) The pyrite concentrate raw material is crushed and sieved to obtain fine pyrite concentrate powder; (2) Air is introduced into the fluidized bed roasting furnace, and the sulfur concentrate fine powder in step (1) is suspended and roasted in the furnace. The excess heat is absorbed by the cooling water in the form of steam. The outlet furnace gas is cooled by heat absorption, and the generated medium-pressure superheated steam is used to generate electricity for the steam turbine generator set. The residue after the fluidized bed roasting furnace and the slag and dust generated during the production process are cooled by water and further humidified by water before being transported out to obtain roasted sand. (3) The furnace gas exiting in step (2) is subjected to dust removal, demisting, further cooling and drying to obtain SO2-containing furnace gas. After replenishing air, sulfuric acid is sprayed, cooled, and the liquid enters the finished product storage tank. The gas is then dried. (4) The dried gas in step (3) undergoes catalytic oxidation and heat exchange treatment, and SO3 in the furnace gas is absorbed by concentrated sulfuric acid. The tail gas is treated by hydrogen peroxide oxidation and demisting before being discharged in compliance with standards. The preparation method of the catalyst used in the catalytic oxidation is as follows: S1. Preparation of porous SiO2 nanospheres: Alkyl ester of orthosilicate was added to ethanol, water and a pore-forming agent were added, the pH value of the solution was adjusted, the reaction was heated and stirred, centrifuged, washed, dried and calcined to obtain porous SiO2 nanospheres; S2. Modification: Porous SiO2 nanospheres were added to ethanol, a silane coupling agent was added, the mixture was heated and stirred to react, filtered, washed, and dried to obtain modified porous SiO2 nanospheres; S3. Loading: Dissolve potassium hydroxide and vanadium pentoxide in water, add concentrated sulfuric acid dropwise, stir to adjust the pH of the solution, add lanthanum nitrate, sulfur and modified porous SiO2 nanospheres, heat and stir to react, filter, wash, dry and calcine to obtain La2O3-doped V2O5-loaded porous SiO2 nanospheres. S4. Preparation of magnetic iron oxide microparticle deposition: Ferric chloride and ferrous chloride were dissolved in water, and under inert gas protection, La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The pH of the solution was adjusted, the reaction was heated and stirred, filtered, washed, dried, and calcined to obtain magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres. S5. Formation of wrinkled heterojunctions: Boron nitride nanosheets and cerium nitrate were added to a mixed solution of ethanol and ethylene glycol, and magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres were added. The mixture was stirred and mixed evenly, followed by hydrothermal reaction, spray drying, and calcination to obtain the catalyst.

2. The method for preparing sulfuric acid from pyrite concentrate powder according to claim 1, characterized in that, The sieve mesh number mentioned in step (1) is 100-300 mesh.

3. The method for preparing sulfuric acid from pyrite concentrate powder according to claim 1, characterized in that, The roasting temperature in step (2) is 850-900℃, and the cooling water is cooling circulating water.

4. The method for preparing sulfuric acid from pyrite concentrate powder according to claim 1, characterized in that, The acid mist content in the exhaust gas emitted in step (4) is less than 5 mg / Nm³. 3 .

5. The method for preparing sulfuric acid from pyrite concentrate powder according to claim 1, characterized in that, In step S1, the alkyl orthosilicate is methyl orthosilicate or ethyl orthosilicate, the mass ratio of the alkyl orthosilicate, ethanol, water and porogen is 10-12:150-180:10-15:0.5-1, the porogen is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride, the pH of the solution is adjusted to 9-11, the temperature of the heating and stirring reaction is 40-50℃, and the time is 8-12h.

6. The method for preparing sulfuric acid from pyrite concentrate powder according to claim 1, characterized in that, In step S2, the mass ratio of porous SiO2 nanospheres to silane coupling agent is 100:2-3. The silane coupling agent is selected from at least one of KH550, KH602, and KH792. The heating and stirring reaction is carried out at a temperature of 45-55°C for 2-4 hours.

7. The method for preparing sulfuric acid from pyrite concentrate powder according to claim 1, characterized in that, In step S3, the mass ratio of potassium hydroxide, vanadium pentoxide, lanthanum nitrate, sulfur, and modified porous SiO2 nanospheres is 1-1.2:1.2-1.4:0.1-0.15:0.5-1:2-4. The pH value of the solution is adjusted to 2-3. The temperature of the heating and stirring reaction is 30-40℃, and the time is 2-4 hours.

8. The method for preparing sulfuric acid from pyrite concentrate powder according to claim 1, characterized in that, In step S4, the mass ratio of ferric chloride, ferrous chloride, and La2O3-doped V2O5-supported porous SiO2 nanospheres is 3.24:1.26:8-10. The pH of the solution is adjusted to 10-11. The temperature of the heating and stirring reaction is 85-95℃, and the time is 3-5h.

9. The method for preparing sulfuric acid from pyrite concentrate powder according to claim 1, characterized in that, In step S5, the mass ratio of boron nitride nanosheets, cerium nitrate, and magnetic La2O3-doped V2O5-supported porous SiO2 nanospheres is 2-3:0.3-0.5:10-12; the volume ratio of ethanol to ethylene glycol in the ethanol and ethylene glycol mixed solution is 2-4:1; and the hydrothermal reaction temperature is 175-185℃, and the time is 0.5-1.5h.

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