Method for producing iron and sulfuric acid by reducing pyrite with hydrogen

Abstract

The invention provides a method for producing iron and sulfuric acid by reducing pyrite with hydrogen. The method comprises the following steps: mixing pyrite powder with a binder, pelletizing, roasting, and melting in an electric arc furnace; hydrogen is blown into the furnace at high temperature for a reduction reaction, and molten iron, furnace slag and hydrogen sulfide gas are obtained; further combusting the hydrogen sulfide gas to generate sulfur dioxide, and converting into sulfuric acid; meanwhile, the slag can be used for smelting industrial silicon or ferrosilicon. According to the method, hydrogen is adopted as a reducing agent, the technological process is shortened, energy consumption is reduced, and the production cost is low. No waste is discharged in the whole production process, and the green production requirement is met.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and particularly to a method for producing iron and sulfuric acid by reducing pyrite with hydrogen. Technical Background

[0002] In the current chemical industry and metallurgical field, pyrite (especially pyrite, mainly composed of FeS2) is an important mineral resource, and its traditional applications mainly focus on the production of sulfuric acid. The existing pyrite utilization technologies mainly follow the following process: First, pyrite is fed into a fluidized bed furnace and reacts violently with oxygen under high-temperature conditions. In this step, pyrite decomposes and releases sulfur dioxide (SO2) and iron oxide (Fe2O3). Subsequently, the generated SO2 gas further undergoes an oxidation reaction with oxygen (O2) under the action of a catalyst (such as vanadium pentoxide V2O5) and is converted into sulfur trioxide (SO3). SO3 has extremely high reactivity and is extremely easy to combine with water (H2O), and finally sulfuric acid (H2SO4) is formed, which is the core product of sulfuric acid industrial production.

[0003] However, while this traditional process brings sulfuric acid production, it also generates a large amount of by-products - pyrite cinder. These cinders are mainly composed of unutilized iron oxide (mainly composed of Fe2O3), and they are discharged as solid waste, which not only occupies valuable land resources but also may cause long-term pollution to the environment due to the presence of heavy metals and other harmful substances. In addition, from the perspective of resource recycling, these iron-rich cinders have not been effectively developed and utilized, which is undoubtedly a huge waste of natural resources.

[0004] In view of the above situation, it is particularly urgent and important to explore and develop a new method that can efficiently and environmentally utilize pyrite cinder, especially the iron resources therein. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for producing iron and sulfuric acid by reducing pyrite with hydrogen.

[0006] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0007] A method for producing iron and sulfuric acid by reducing pyrite with hydrogen, comprising the following steps:

[0008] Step S1, mixing and pelletizing: Mix pyrite powder and a binder evenly to form pellets;

[0009] Step S2, drying: Dry the formed pellets at 200°C to 300°C;

[0010] Step S3, smelting reduction: Add the roasted pellets to the electric arc furnace, or directly add massive pyrite to the electric arc furnace, melt at 1500°C to 1600°C, and blow hydrogen into the furnace for reduction reaction to obtain molten iron, slag and hydrogen sulfide gas; the reaction equation is:

[0011] FeS2 + 2H2 = Fe + 2H2S

[0012] FeS + H2 = Fe + H2S;

[0013] Step S4, generating SO2: Pass the hydrogen sulfide gas into the combustion chamber, burn to generate SO2, and the reaction equation is:

[0014] 2H2S + 3O2 = 2H2O + 2SO2

[0015] 2H2 + O2 = 2H2O;

[0016] Step S5, generating sulfuric acid: The heat of the gas coming out of the combustion chamber can be used for power generation. Pass the gas into the absorption tower, spray dilute sulfuric acid from the top of the absorption tower, SO2 reacts with water to form sulfurous acid, and sulfurous acid is then oxidized to form sulfuric acid; the reaction equations are:

[0017] SO2 + H2O = H2SO3

[0018] 2H2SO3 + O2 = 2H2SO4;

[0019] Or, pass the gas coming out of the combustion chamber into the reaction chamber, generate sulfur trioxide under the action of a catalyst, and then react with water to form sulfuric acid. The reaction equations are:

[0020] 2SO2 + O2 = SO3

[0021] H2O + SO3 = H2SO4.

[0022] Among them, in step S1, the binder is bentonite, and calculated by mass percentage, the addition amount of the binder is 1% - 3% of the pyrite.

[0023] Among them, in step S1, the diameter of the pellets is 20mm - 30mm, and the water content of the pellets is less than 10%.

[0024] Among them, the sintering temperature in step S2 is 200°C - 300°C, and it is dried to a water content of less than 1%.

[0025] Among them, in step S3, the particle size of the massive pyrite is 20mm - 30mm.

[0026] Among them, in step S3, the melting temperature is 1550°C - 1600°C.

[0027] Among them, in step S5, the catalyst is vanadium pentoxide (V2O5).

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) Short process flow and low energy consumption:

[0030] By directly using hydrogen to reduce pyrite, the present invention simplifies the process flow and greatly reduces the energy consumption. As a reducing agent, hydrogen has high reactivity and can effectively reduce pyrite at a lower temperature, thus reducing energy consumption.

[0031] (2) Low production cost:

[0032] The raw material pyrite used in this method is rich in resources and low in price. Due to the simplification of the process flow and the reduction of energy consumption, the production cost is further reduced and the economic benefit is improved.

[0033] (3) No waste discharge, green production:

[0034] The hydrogen sulfide gas generated in the iron-making process of the present invention is effectively utilized and converted into valuable products such as sulfuric acid. The slag is used for smelting industrial silicon or ferrosilicon, and no waste is generated in the production process, meeting the requirements of green production and having a positive significance for environmental protection.

[0035] (4) Good quality of the prepared product:

[0036] Due to the strong reducibility of hydrogen, it can fully reduce the iron in pyrite, and the prepared molten iron has high purity and good quality. Specific embodiments

[0037] The following is a detailed description in combination with specific embodiments, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. The raw materials used in the examples are all commercially available unless otherwise specified.

[0038] Example 1 Method for producing iron and sulfuric acid by reducing pyrite with hydrogen

[0039] Step S1, mixing and pelletizing: Mix pyrite powder (FeS 8.16, FeS2 82.83, SiO2 7.37, CaO 1.64) with a binder (bentonite) evenly to form pellets with a diameter of 25 mm and a water content of 8%; among them, calculated by mass percentage, the addition amount of the binder is 2% of the pyrite;

[0040] Step S2, drying: Dry the formed pellets at 300 °C until the water content is below 1%;

[0041] Step S3, smelting reduction: Add the roasted pellets into an electric arc furnace and melt them at 1500 °C. Inject hydrogen into the furnace for reduction reaction to obtain molten iron, slag and hydrogen sulfide gas. The molten iron is used for steelmaking or casting. The slag is used to produce industrial silicon or ferrosilicon. The reaction equation is:

[0042] FeS2 + 2H2 = Fe + 2H2S

[0043] FeS + H2 = Fe + H2S;

[0044] Step S4, generating SO2: Inject the hydrogen sulfide gas into a combustion chamber and burn it to generate SO2. The reaction equation is:

[0045] 2H2S + 3O2 = 2H2O + 2SO2

[0046] 2H2 + O2 = 2H2O;

[0047] Step S5, generating sulfuric acid: The heat of the gas coming out of the combustion chamber is used for power generation. Inject the gas into an absorption tower and spray dilute sulfuric acid from the top of the absorption tower. SO2 reacts with water to form sulfurous acid, and the sulfurous acid is then oxidized to form sulfuric acid. The reaction equations are:

[0048] SO2 + H2O = H2SO3

[0049] 2H2SO3 + O2 = 2H2SO4

[0050] Example 2 Method for producing iron and sulfuric acid by reducing pyrite with hydrogen

[0051] Step S1, directly add massive pyrite with a particle size of 20 mm to 30 mm (FeS 8.16, FeS2 82.83, SiO2 7.37, CaO 1.64) into an electric arc furnace and melt it at 1550 °C. Inject hydrogen into the furnace for reduction reaction to obtain molten iron, slag and hydrogen sulfide gas. The molten iron is used for steelmaking or casting. The slag is used to produce industrial silicon or ferrosilicon. The reaction equations are:

[0052] FeS2 + 2H2 = Fe + 2H2S

[0053] FeS + H2 = Fe + H2S;

[0054] Step S2, generating SO2: Inject the hydrogen sulfide gas into a combustion chamber and at the same time inject oxygen into the combustion chamber. The hydrogen sulfide gas burns to generate SO2. The reaction equation is:

[0055] 2H2S + 3O2 = 2H2O + 2SO2

[0056] 2H2 + O2 = 2H2O;

[0057] Step S3, generate sulfuric acid: The heat of the gas coming out of the combustion chamber can be used for power generation. The gas is introduced into the absorption tower, and dilute sulfuric acid is sprayed from the top of the absorption tower. SO2 reacts with water to form sulfurous acid, and sulfurous acid is then oxidized to form sulfuric acid. The reaction equations are:

[0058] SO2 + H2O = H2SO3

[0059] 2H2SO3 + O2 = 2H2SO4;

[0060] Example 3 A method for producing iron and sulfuric acid by reducing pyrite with hydrogen

[0061] Step S1, mixing and pelletizing: Mix pyrite powder (FeS 8.16, FeS2 82.83, SiO2 7.37, CaO 1.64) with a binder (bentonite) evenly to form pellets with a diameter of 30 mm and a water content of 8%. Among them, by mass percentage, the addition amount of the binder is 1% of the pyrite.

[0062] Step S2, drying: Dry the formed pellets at 280 °C to obtain pellets with a water content below 1%.

[0063] Step S3, melting and reduction: Add the roasted pellets to an electric arc furnace, melt at 1500 °C, and blow hydrogen into the furnace for reduction reaction to obtain molten iron, slag and hydrogen sulfide gas. The molten iron is used for steelmaking or casting into castings. The slag is used to manufacture industrial silicon or ferrosilicon. The reaction equations are:

[0064] FeS2 + 2H2 = Fe + 2H2S

[0065] FeS + H2 = Fe + H2S;

[0066] Step S4, generate SO2: Introduce hydrogen sulfide gas into the combustion chamber, and at the same time introduce oxygen into the combustion chamber. The hydrogen sulfide gas burns to generate SO2. The reaction equation is:

[0067] 2H2S + 3O2 = 2H2O + 2SO2

[0068] 2H2 + O2 = 2H2O;

[0069] Step S5, generate sulfuric acid: The heat of the gas coming out of the combustion chamber can be used for power generation. The gas is introduced into the reaction chamber, and sulfur trioxide is generated under the action of vanadium pentoxide (V2O5). SO3 is introduced into the absorption tower, and dilute sulfuric acid is sprayed from the top of the absorption tower. SO3 reacts with water to form sulfuric acid. The reaction equations are:

[0070] 2SO2 + O2 = SO3

[0071] H2O + SO3 = H2SO4.

[0072] Example 4 Method for Producing Iron and Sulfuric Acid by Reducing Pyrite with Hydrogen

[0073] Step S1, Mixing and Pelletizing: Mix pyrite powder (FeS 8.16, FeS₂ 82.83, SiO₂ 7.37, CaO 1.79) with a binder (bentonite) evenly to form pellets with a diameter of 30 mm and a water content of 8%; among them, calculated by mass percentage, the addition amount of the binder is 3% of the pyrite.

[0074] Step S2, Drying: Roast the formed pellets at 250 °C to obtain pellets with a water content of less than 1%.

[0075] Step S3, Melting and Reduction: Add the dried pellets to an electric arc furnace, melt at 1600 °C, blow hydrogen into the furnace for reduction reaction to obtain molten iron, slag and hydrogen sulfide gas. The molten iron is used for steelmaking or casting into castings. The slag is used to manufacture industrial silicon or ferrosilicon; the reaction equations are:

[0076] FeS₂ + 2H₂ = Fe + 2H₂S

[0077] FeS + H₂ = Fe + H₂S;

[0078] Step S4, Generating SO₂: Pass the hydrogen sulfide gas into a combustion chamber, and at the same time pass oxygen into the combustion chamber. The hydrogen sulfide gas burns to generate SO₂, and the reaction equation is:

[0079] 2H₂S + 3O₂ = 2H₂O + 2SO₂

[0080] 2H₂ + O₂ = 2H₂O;

[0081] Step S5, Generating Sulfuric Acid: The heat of the gas coming out of the combustion chamber is used for power generation. After purifying the gas, pass it into an absorption tower, spray dilute sulfuric acid from the top of the absorption tower. SO₂ reacts with water to form sulfurous acid, and the sulfurous acid is then oxidized to form sulfuric acid; the reaction equations are:

[0082] SO₂ + H₂O = H₂SO₃

[0083] 2H₂SO₃ + O₂ = 2H₂SO₄.

[0084] The foregoing description of the specific exemplary embodiments of the present invention is for the purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many changes and variations are possible in light of the above teaching. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize the various different exemplary embodiments of the invention, as well as various different selections and changes. The scope of the invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for producing iron and sulfuric acid by reducing pyrite with hydrogen, characterized in that, It includes the following steps: Step S1, mixing and pelletizing: Mix pyrite powder with a binder and water evenly to form pellets; Step S2, sintering: Sinter the formed pellets at 200°C to 300°C; Step S3, smelting reduction: Add the sintered pellets to an electric arc furnace, or directly add massive pyrite to the electric arc furnace, melt at 1500°C to 1600°C, and blow hydrogen into the furnace for reduction reaction to obtain molten iron, slag and hydrogen sulfide gas; The reaction equation is: FeS2 + 2H2 = Fe + 2H2S FeS + H2 = Fe + H2S; Step S4, generating SO2: Pass the hydrogen sulfide gas into a combustion chamber, and at the same time pass oxygen into the combustion chamber. H2S and O2 react to generate SO2. The reaction equation is: 2H2S + 3O2 = 2H2O + 2SO2 2H2 + O2 = 2H2O; Step S5, generating sulfuric acid: The heat of the gas coming out of the combustion chamber can be used for power generation. After power generation, pass the gas into an absorption tower, spray dilute sulfuric acid from the top of the absorption tower. SO2 reacts with water to form sulfurous acid, and then sulfurous acid is oxidized to form sulfuric acid; The reaction equation is: SO2 + H2O = H2SO3 2H2SO3 + O2 = 2H2SO4; Or, pass the gas coming out of the combustion chamber into a reaction chamber, generate sulfur trioxide under the action of a catalyst, and then react with water to form sulfuric acid. The reaction equation is: 2SO2 + O2 = SO3 H2O + SO3 = H2SO4.

2. The method according to claim 1, wherein: In step S1, the binder is bentonite. By mass percentage, the addition amount of the binder is 1% to 3% of the pyrite.

3. The method according to claim 1, characterized in that: In step S1, the diameter of the pellets is 20mm to 30mm, and the water content of the pellets is less than 10%.

4. The method according to claim 1, characterized in that: The sintering temperature in step S2 is 300°C, and it is dried to a water content of less than 1%.

5. The method according to claim 1, characterized in that: In step S3, the particle size of the massive pyrite is 20mm to 30mm.

6. The method according to claim 1, characterized in that: In step S3, the melting temperature is 1550°C to 1600°C.

7. The method according to claim 1, characterized in that: In step S5, the catalyst is vanadium pentoxide.