Process for utilizing heat energy from sulfuric acid production

Abstract

A process for utilizing heat energy from sulfuric acid production. A first heat exchanger (1-1) and / or a second heat exchanger (2-1) and / or a third heat exchanger (3-1) are additionally provided in a sulfuric acid production process, wherein the first heat exchanger (1-1) heats air that enters a sulfur burner, and transfers high-temperature heat in flue gas to a steam system in a waste heat boiler to generate medium- and high-pressure steam; the second heat exchanger (2-1) heats the flue gas that comes out from an HRS tower, and the heated flue gas enters a cold-to-hot heat exchanger for heat exchange with flue gas from a third section of a converter and is thus further heated to meet process requirements; and the third heat exchanger (3-1) heats boiler feed water from a boiler feed water pump, the heated boiler feed water then enters an economizer 3A and / or economizer 4B, and the heat added by the boiler feed water is used to generate medium- and high-pressure steam. Compared with the prior art, three heat exchangers are additionally provided, and flexible configurations are utilized on the basis of different usage scenarios and objects, thereby significantly improving the yield of medium- and high-pressure steam.

Description

Process for utilizing heat energy in sulfuric acid production TECHNICAL FIELD

[0001] [Corresponding to Rule 91, 07.08.2024] The present invention relates to the technical field of heat energy utilization, in particular to a process for utilizing heat energy in sulfuric acid production. BACKGROUND

[0002] [Corresponding to Rule 91, 07.08.2024] Currently, whether the heat recovery system of the sulfuric acid industry is efficient is the top priority of the entire device. The ton acid steam production of the sulfur-burning sulfuric acid device is 1.25-1.32 t / t in medium-high pressure steam of 3.0-9.8 MPa, 400-540 ℃, 0.6-1.0 MPa, saturated steam low-temperature heat recovery system, abbreviated as HRS (Heat Recovery Systems), produces 0.45 t / t of low-pressure steam; The price difference between the two kinds of steam in the market is large; Therefore, it is an urgent pursuit of the sulfuric acid industry to maximize the production of medium-high pressure steam and generate more economic benefits. SUMMARY

[0003] [Corresponding to Rule 91, 07.08.2024] In order to overcome the shortcomings of the prior art, the present invention provides a process for further utilizing heat energy in sulfuric acid production, which can transfer low-temperature heat energy to high-temperature heat energy and produce as much medium-high pressure steam as possible to generate more economic benefits.

[0004] [Corresponding to Rule 91, 07.08.2024] In order to achieve the above-mentioned purpose, a process for utilizing heat energy in sulfuric acid production is designed, and a first heat exchanger and / or a second heat exchanger and / or a third heat exchanger are added to the sulfuric acid production process,

[0005] [Corresponding to Rule 91, 07.08.2024] The first heat exchanger 1-1 heats the air entering the sulfur incinerator, the heated air enters the sulfur incinerator, the flue gas after the combustion reaction enters the waste heat boiler, and the high-temperature heat in the flue gas is transferred to the steam system in the waste heat boiler to produce medium-high pressure steam;

[0006] [Corresponding to Rule 91, 07.08.2024] The second heat exchanger 2-1 heats the flue gas from the HRS tower, the heated flue gas enters the cold-heat heat exchanger and exchanges heat with the flue gas from the outlet of the third section of the converter to further heat it to meet the process requirements, reduce the heat consumption of another flue gas from the cold-heat heat exchanger, and heat the high-pressure hot water through the coal economizer 3A to transfer the heat energy to the steam system for utilization;

[0007] [Rule 91 correction 07.08.2024] The third heat exchanger 3-1 heats the boiler feed water from the boiler feed water pump and enters the economizer 3A and / or the economizer 4B, or as the heat source of the first heat exchanger 1-1, the second heat exchanger 2-1, and then enters the economizer 3A and / or the economizer 4B, and the heat added to this part of the boiler feed water is used to generate medium and high pressure steam.

[0008] [Rule 91 correction 07.08.2024] The first heat exchanger is installed before the sulfur furnace inlet, the second heat exchanger is installed between the HRS tower and the cold-heat heat exchanger, and the third heat exchanger is installed between the boiler feed water pump and the economizer.

[0009] [Rule 91 correction 07.08.2024] The first heat exchanger, the second heat exchanger, and the third heat exchanger are all provided with temperature detection points and control valves, and the amount of material entering the heat exchanger is adjusted according to the set temperature parameter to control the temperature.

[0010] [Rule 91 correction 07.08.2024] The source of the heating medium in the first heat exchanger and the second heat exchanger is one or more of high-temperature sulfuric acid, high-pressure hot water, high-pressure steam, low-pressure steam, and external heat sources generated in the sulfuric acid production process.

[0011] [Rule 91 correction 07.08.2024] The heat source of the third heat exchanger comes from the high-temperature sulfuric acid generated by the HRS tower, which enters the heat source medium inlet of the third heat exchanger to exchange heat with the boiler feed water, and then flows out from the heat source medium outlet of the third heat exchanger.

[0012] [Rule 91 correction 07.08.2024] The materials in contact with high-temperature acid in the first heat exchanger, the second heat exchanger, and the third heat exchanger are selected from acid-resistant stainless steel, and the materials in contact with hot water and steam are selected from carbon steel.

[0013] [Rule 91 correction 07.08.2024] The second heat exchanger heats the flue gas from the cold-heat heat exchanger, reducing the heat consumed by another flue gas from the cold-heat heat exchanger, and heating the high-pressure hot water through the economizer 3A to transfer heat energy to the steam system for utilization.

[0014] [Rule 91 correction 07.08.2024] The sulfuric acid production process includes but is not limited to sulfuric acid production, pyrite acid production, and smelter flue gas acid production.

[0015] [Rule 91 correction 07.08.2024] The invention increases three sets of heat exchangers compared with the prior art. Each set of heat exchangers can be used separately or in any combination or joint use. According to different use scenarios and objects, flexible configuration is made to significantly improve the yield of medium and high pressure steam. As much as possible, high temperature sulfuric acid, hot water, steam, flue gas in the sulfuric acid production process or energy outside the sulfuric acid production process is used as a heat source to improve the heat energy recovery rate. BRIEF DESCRIPTION OF DRAWINGS

[0016] [Rule 91 correction 07.08.2024] Figure 1 is a process flow diagram of the flue gas and acid system in the sulfuric acid production process of the invention.

[0017] [Rule 91 correction 07.08.2024] Figure 2 is a process flow diagram of the water and steam process in the sulfuric acid production process of the invention. DETAILED DESCRIPTION

[0018] [Rule 91 correction 07.08.2024] Referring to Figures 1 to 2, wherein 1-1 is the first heat exchanger, 2-1 is the second heat exchanger, 3-1 is the third heat exchanger, 4-1 is liquid sulfur, 4-2 is air, 4-3 is an air filter, 4-4 is a drying tower, 4-5 is a main fan, 4-6 is a sulfur incinerator, 4-7 is a waste heat boiler, 4-8 is a converter, 4-9 is a high temperature superheater 1B, 4-10 is a hot heat exchanger, 4-11 is a cold heat exchanger, 4-12 is an economizer 3A, 4-13 is an ejector, 4-14 is low pressure steam, 4-15 is an HRS tower, 4-16 is an HRS acid circulating pump, 4-17 is a superheater 4A, 4-18 is an economizer 4B, 4-19 is an economizer 4A, 4-20 is a secondary absorption tower, 4-21 is a tail absorption device, 4-22 is a secondary absorption acid pump tank, 4-23 is a secondary absorption acid cooler, 4-24 is a finished acid cooler, 4-25 is finished acid, 4-26 is an HRS boiler, 4-27 is an HRS heater, 4-28 is an HRS diluter, 4-29 is another HRS heater, 4-30 is a dry acid pump tank, 4-31 is a dry acid cooler, 4-32 is a pump tank dilution water, 4-33 is HRS dilution water, 4-34 is desalted water (0.4Mpa), 4-35 is a deaerator, 4-36 is a boiler feed water pump, 4-37 is a boiler dosing device, 4-38 is medium and high pressure superheated steam, 4-39 is a continuous blowdown expander, 4-40 is a periodic blowdown expander, 4-41 is a vent port, 4-42 is a blowdown port, 4-43 is low pressure saturated steam, 4-44 is low pressure injection steam, 4-45 is an HRS blowdown tank, 4-46 is another vent port, 4-47 is another blowdown port, and 4-48 is low pressure steam.

[0019] [Rule 91 correction 07.08.2024] The invention is further described below with reference to the accompanying drawings.

[0020] [According to Rule 91 correction 07.08.2024] As shown in Figures 1-2, the present application is a process for utilizing heat energy in sulfuric acid production, specifically, adding a first heat exchanger 1-1 and / or a second heat exchanger 2-1 and / or a third heat exchanger 3-1 to the existing sulfuric acid production process,

[0021] [According to Rule 91 correction 07.08.2024] The first heat exchanger 1-1 heats the air entering the sulfur incinerator from 60-130°C to 180-280°C, the heated air enters the sulfur incinerator, and the flue gas after the combustion reaction enters the waste heat boiler, transferring the high-temperature heat in the flue gas to the steam system in the waste heat boiler (i.e. water vapor No. 118 in Figure 2), generating more medium and high pressure steam.

[0022] [According to Rule 91 correction 07.08.2024] The second heat exchanger 2-1 heats the flue gas (No. 18) from the HRS tower from 70-90°C to 100-190°C, and the heated flue gas (No. 19) enters the cold-hot heat exchanger and exchanges heat with the flue gas (No. 14) from the third outlet of the converter, further heating to about 330°C (No. 20), meeting the process requirements; the flue gas (No. 14) from the third outlet of the converter has a temperature of 450-470°C, and the flue gas (No. 15) after heat exchange in the cold-hot heat exchanger has a temperature of about 310-350°C, which is usually about 250-280°C in traditional processes, which is 60-100°C higher, and the part of the heat that is higher in the improved process than in the traditional process is the heat transferred from the low-temperature heat source, which is absorbed and utilized by the coal economizer 3A, generating more medium and high pressure steam.

[0023] [According to Rule 91 correction 07.08.2024] The third heat exchanger 3-1 heats the boiler feed water (No. 110) from the boiler feed water pump from 104-135°C to 145-150°C before entering the coal economizer 3A and / or the coal economizer 4B, or as a heat source for the first heat exchanger 1-1 and the second heat exchanger 2-1 before entering the coal economizer 3A and / or the coal economizer 4B. The temperature and heat of the boiler feed water to the coal economizer are improved, ultimately improving the production of medium and high pressure steam.

[0024] [Corrected according to Rule 91 on 07.08.2024] The equipment of the sulfuric acid production process includes a drying tower, a fan, a sulfur incinerator, a converter, an HRS tower, the drying tower inlet is connected with an air filter, the drying tower outlet is connected with one end of the main fan, the other end of the main fan is connected with the inlet of the sulfur incinerator, the outlet of the sulfur incinerator is connected with the inlet of the waste heat boiler, the outlet of the waste heat boiler is connected with the inlet of the first section of the converter, the outlet of the first section of the converter is connected with the inlet of the high-temperature superheater 1B, the outlet of the high-temperature superheater 1B is connected with the inlet of the second section of the converter, the outlet of the second section of the converter is connected with the first inlet of the hot heat exchanger, the first outlet of the hot heat exchanger is connected with the inlet of the third section of the converter, the outlet of the third section of the converter is connected with the first inlet of the cold heat exchanger, the first outlet of the cold heat exchanger is connected with the inlet of the economizer 3A, the outlet of the economizer 3A is connected with the flue gas inlet of the HRS absorption tower, the flue gas outlet of the HRS absorption tower is connected with the second inlet of the cold heat exchanger, the second outlet of the cold heat exchanger is connected with the second inlet of the hot heat exchanger, the second outlet of the hot heat exchanger is connected with the fourth section inlet of the converter, the fourth section outlet of the converter is connected with the inlet of the second absorption tower through the superheater 4A, the economizer 4B and the economizer 4A respectively, the flue gas outlet of the second absorption tower is connected with the tail suction device, the acid outlet of the second absorption tower is connected with the second absorption acid pump tank, the acid side outlet of the HRS absorption tower pump tank is connected with the inlet of the HRS boiler through the HRS acid circulating pump, the outlet of the HRS boiler is connected with the inlet of the HRS heater and the inlet of the HRS diluter respectively, the outlet of the HRS heater is connected with the acid side inlet of the HRS preheater, the acid outlet of the HRS preheater is connected with the second absorption acid pump tank, the acid outlet of the second absorption acid pump tank is connected with the inlet of the finished acid cooler, and the outlet of the finished acid cooler obtains finished acid. In the sulfuric acid production process, air is filtered through an air filter, the filtered air is dried in a drying tower, then the dried air is pressurized by a fan and enters a sulfur incinerator, burns and reacts with liquid sulfur in the sulfur incinerator to generate high-temperature SO2 flue gas, the flue gas enters a waste heat boiler, the high-temperature heat in the flue gas is transferred to a steam system in the waste heat boiler to generate medium and high pressure steam, the flue gas from the waste heat boiler enters a converter for catalytic oxidation, the flue gas from the third section outlet of the converter is cooled by a cold heat exchanger and an economizer 3A, then enters an HRS tower for SO3 absorption, the flue gas from the flue gas outlet of the HRS tower is cooled by a cold heat exchanger and a hot heat exchanger, then enters the fourth section of the converter for catalytic oxidation again, the flue gas from the fourth section outlet of the converter is cooled by a superheater 4A, an economizer 4B and an economizer 4A, then enters a second absorption tower for secondary SO3 absorption, high-temperature sulfuric acid produced by the HRS tower is combined after passing through an HRS boiler and a third heat exchanger, then is divided into two parts, one part enters an HRS heater, then enters a second absorption acid pump tank to react to generate sulfuric acid, then passes through a finished acid cooler to obtain finished acid, the other part of the high-temperature sulfuric acid passes through an HRS diluter, is diluted by water and mixed with acid, then returns to the HRS tower for repeated absorption process.

[0025] [According to the rules 91 correction 07.08.2024] The first heat exchanger 1-1 is installed before the sulfur furnace inlet, the second heat exchanger 2-1 is installed between the HRS tower and the cold-heat heat exchanger, and the third heat exchanger 3-1 is installed between the boiler feed water pump and the economizer.

[0026] [According to the rules 91 correction 07.08.2024] The first heat exchanger 1-1, the second heat exchanger 2-1, and the third heat exchanger 3-1 are provided with temperature detection points and control valves, and the amount of material entering the heat exchanger is adjusted according to the set temperature parameter to control the temperature.

[0027] [According to the rules 91 correction 07.08.2024] The source of heating medium in the first heat exchanger 1-1 and the second heat exchanger 2-1 is one or more of high-temperature sulfuric acid, high-pressure hot water, high-pressure steam, and low-pressure steam generated in the sulfuric acid production process. In specific use, it can also or use heat sources outside the sulfuric acid production process. Among them, the source of high-temperature sulfuric acid includes one or more of the smoke of serial number 64, serial number 66, serial number 68, serial number 72, and serial number 73 in Figure 1. The source of high-pressure hot water includes one or more of serial number 111 and serial number 113 in Figure 2. The source of high-pressure steam includes one or more of serial number 119 and serial number 120 in Figure 2. The source of high-pressure steam includes serial number 125 in Figure 2.

[0028] [According to the rules 91 correction 07.08.2024] The heat source of the third heat exchanger 3-1 comes from the high-temperature sulfuric acid (serial number 67) generated by the HRS tower, with a temperature of 200-230°C. The high-temperature sulfuric acid acts as the heat source medium of the third heat exchanger, exchanges heat with the high-pressure boiler feed water (serial number 110), and then flows out from the heat source medium outlet of the third heat exchanger.

[0029] [According to the rules 91 correction 07.08.2024] The first heat exchanger 1-1 is an air heater, the second heat exchanger 2-1 is a flue gas heater, and the third heat exchanger 3-1 is an HRS high-pressure heater.

[0030] [According to the rules 91 correction 07.08.2024] The materials in contact with high-temperature acid in the first heat exchanger 1-1, the second heat exchanger 2-1, and the third heat exchanger 3-1 are selected from acid-resistant stainless steel, and the materials in contact with hot water and steam are selected from carbon steel.

[0031] [According to the rules 91 correction 07.08.2024] In this embodiment, the second heat exchanger 2-1 heats the flue gas (serial number 15) from the cold-heat heat exchanger, reducing the heat consumed by another flue gas from the cold-heat heat exchanger, and heating the high-pressure hot water (serial number 112) through the economizer 3A, transferring the heat energy to the steam system for utilization. Example one

[0032] [Rule 91 correction 07.08.2024] The sulfuric acid production process includes but is not limited to sulfur-burning, pyrite-burning, and smelter off-gas-burning.

[0033] [Rule 91 correction 07.08.2024] In this embodiment, a first heat exchanger 1-1 is added to the existing sulfuric acid production process. The high-temperature sulfuric acid obtained from the HRS tower is used to heat the air entering the sulfur-burning furnace, transferring low-temperature heat energy to the subsequent medium / high-pressure steam system.

[0034] [Rule 91 correction 07.08.2024] In another embodiment of this embodiment, the air entering the sulfur-burning furnace is heated by the heat from the third heat exchanger 3-1 in the system (serial number 111), transferring low-temperature heat energy to the subsequent medium / high-pressure steam system. Embodiment Two

[0035] [Rule 91 correction 07.08.2024] In another embodiment of this embodiment, the air entering the sulfur-burning furnace is heated by the heat source generated by external equipment, transferring low-temperature heat energy to the subsequent medium / high-pressure steam system.

[0036] [Rule 91 correction 07.08.2024] In this embodiment, a second heat exchanger 2-1 is added to the existing sulfuric acid production process. The high-temperature sulfuric acid obtained from the HRS tower is used to heat the flue gas at the outlet of the HRS tower, transferring low-temperature heat energy to the subsequent medium / high-pressure steam system.

[0037] [Rule 91 correction 07.08.2024] In another embodiment of this embodiment, the flue gas at the outlet of the HRS tower is heated by the waste heat from the flue gas in the system, transferring low-temperature heat energy to the subsequent medium / high-pressure steam system. Embodiment Three

[0038] [Rule 91 correction 07.08.2024] In another embodiment of this embodiment, the flue gas at the outlet of the HRS tower is heated by the heat source generated by external equipment, transferring low-temperature heat energy to the subsequent medium / high-pressure steam system. Embodiment Four

[0039] [Rule 91 correction 07.08.2024] In this embodiment, a third heat exchanger 3-1 is added to the existing sulfuric acid production process. The high-temperature sulfuric acid obtained from the HRS tower is used to heat the medium / high-pressure boiler feedwater, transferring low-temperature heat energy to the subsequent medium / high-pressure steam system.

[0040] [Rule 91 correction 07.08.2024] In this embodiment, a first heat exchanger 1-1 and a second heat exchanger 2-1 are added to the existing sulfuric acid production process. The high-temperature sulfuric acid obtained by the HRS tower is used to heat the air entering the sulfuric acid furnace and / or the flue gas at the outlet of the HRS tower, transferring low-temperature heat energy to the medium and high-pressure steam system. Example Five

[0041] [Rule 91 correction 07.08.2024] In another embodiment of this embodiment, the high-temperature sulfuric acid obtained by the HRS tower is used to generate low-pressure steam, which is then used to heat the air entering the sulfuric acid furnace and / or the flue gas at the outlet of the HRS tower, transferring low-temperature heat energy to the medium and high-pressure steam system.

[0042] [Rule 91 correction 07.08.2024] This embodiment only explains the differences from Example One, and the same parts are not repeated. Example Six

[0043] [Rule 91 correction 07.08.2024] The difference between this embodiment and Example One is that a third heat exchanger is added to the sulfuric acid production process in this embodiment. The high-temperature sulfuric acid obtained by the HRS tower is used to heat the medium and high-pressure boiler feedwater, transferring low-temperature heat energy to the subsequent medium and high-pressure steam system.

[0044] [Rule 91 correction 07.08.2024] This embodiment only explains the differences from Example Two, and the same parts are not repeated. Example Seven

[0045] [Rule 91 correction 07.08.2024] The difference between this embodiment and Example Two is that a third heat exchanger is added to the sulfuric acid production process in this embodiment. The high-temperature sulfuric acid obtained by the HRS tower is used to heat the medium and high-pressure boiler feedwater, transferring low-temperature heat energy to the subsequent medium and high-pressure steam system.

[0046] [Rule 91 correction 07.08.2024] This embodiment only explains the differences from Example Four, and the same parts are not repeated.

[0047] [Rule 91 correction 07.08.2024] The difference between this embodiment and Example Four is that a third heat exchanger is added to the sulfuric acid production process in this embodiment. The high-temperature sulfuric acid obtained by the HRS tower is used to heat the medium and high-pressure boiler feedwater, transferring low-temperature heat energy to the subsequent medium and high-pressure steam system.

[0048] [Corresponding to Rule 91 correction 07.08.2024]The present application increases three sets of heat exchangers, each of which can be used alone or in any combination, joint use, according to the use scene, object different do flexible configuration, significantly improve the yield of medium and high pressure steam. As much as possible to use high temperature sulfuric acid, hot water, steam, flue gas in sulfuric acid production process as heat source, improve the heat recovery rate. By setting the heat exchange system, the low temperature heat energy is transferred to the high temperature heat energy system, which can realize the medium and high pressure steam 1.41~1.55t / t acid, at the same time, the low pressure steam 0.31~0.26t / t acid, maximize the economic benefit.

Claims

1. A process for the utilization of thermal energy in sulfuric acid production, characterized by: The sulfuric acid production process is additionally provided with a first heat exchanger (1-1) and / or a second heat exchanger (2-1) and / or a third heat exchanger (3-1), The first heat exchanger (1-1) heats the air entering the sulfur incinerator, the heated air enters the sulfur incinerator, the flue gas after the combustion reaction enters the waste heat boiler, the high-temperature heat in the flue gas is transferred to the steam system in the waste heat boiler to generate medium-pressure and high-pressure steam; The second heat exchanger (2-1) heats the flue gas from the HRS tower, the heated flue gas enters the cold-heat heat exchanger and exchanges heat with the flue gas from the outlet of the third section of the converter to further heat up to meet the process requirements, reduces the heat consumption of another flue gas from the cold-heat heat exchanger, and heats the high-pressure hot water through the economizer 3A to transfer the heat energy to the steam system for utilization. The third heat exchanger (3-1) heats the boiler feed water from the boiler feed water pump and enters the economizer 3A and / or the economizer 4B, or enters the economizer 3A and / or the economizer 4B after being the heat source of the first heat exchanger 1-1 and the second heat exchanger 2-1, and the increased heat of the boiler feed water is used to generate medium-pressure and high-pressure steam.

2. A process for the utilization of thermal energy in sulfuric acid production according to claim 1 characterized in that: The first heat exchanger (1-1) is installed before the inlet of the sulfur incinerator, the second heat exchanger (2-1) is installed between the HRS tower and the cold-heat heat exchanger, and the third heat exchanger (3-1) is installed between the boiler feed water pump and the economizer.

3. A process for the utilization of heat energy in sulfuric acid production according to claim 1 characterized in that: The first heat exchanger (1-1), the second heat exchanger (2-1), and the third heat exchanger (3-1) are all provided with temperature detection points and control valves, and the amount of material entering the heat exchanger is adjusted according to the set temperature parameters to control the temperature.

4. A process for the utilization of heat energy in sulfuric acid production according to claim 1 characterized in that: The source of the heating medium in the first heat exchanger (1-1) and the second heat exchanger (2-1) is one or more of high-temperature sulfuric acid, high-pressure hot water, high-pressure steam, low-pressure steam, and external heat sources generated in the sulfuric acid production process.

5. A process for the utilization of heat energy in sulfuric acid production according to claim 1 characterized in that: The heat source of the third heat exchanger (13-1) is high-temperature sulfuric acid generated from the HRS tower, which enters the heat source medium inlet of the third heat exchanger (3-1) to exchange heat with the boiler feed water, and then flows out from the heat source medium outlet of the third heat exchanger.

6. A process for the utilization of heat energy in sulfuric acid production according to claim 1 characterized in that: The materials in contact with high-temperature acid in the first heat exchanger (1-1), the second heat exchanger (2-1), and the third heat exchanger (3-1) are selected from acid-resistant stainless steel, and the materials in contact with hot water and steam are selected from carbon steel.

7. A process for the utilization of heat energy in sulfuric acid production according to claim 1 characterized in that: The second heat exchanger (2-1) heats the flue gas from the cold-heat heat exchanger, reduces the heat consumption of another flue gas from the cold-heat heat exchanger, and heats the high-pressure hot water through the economizer 3A to transfer the heat energy to the steam system for utilization.

8. A process for the utilization of heat energy in sulfuric acid production according to claim 1 characterized in that: The sulfuric acid production process includes but is not limited to sulfuric acid production from sulfur, sulfuric acid production from pyrite, and smelter flue gas acid production.

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