Treatment method of sulfur-containing waste

Abstract

The invention discloses a sulfur-containing waste treatment method which comprises the following steps: mixing an ore raw material with sulfur-containing waste, evaporating moisture, sieving with a screen, combusting with air to generate furnace gas, pumping the generated furnace gas into a waste heat recovery device, recovering heat energy, feeding the cooled furnace gas into a purification device, and purifying the furnace gas to obtain the sulfur-containing waste. Ash and acid mist in furnace gas are removed through gravity, pickling and electric field effects, the furnace gas enters a conversion device after being humidified, cooled and dried and is catalyzed into converted gas through vanadium catalysts in different conversion layers after being mixed with air, and the converted gas enters an absorption tower and is absorbed by water or sulfuric acid to generate finished acid. The converted and absorbed tail gas enters a tail gas treatment device to be cleaned and discharged after reaching the standard. The sulfur-containing waste is co-treated by using the existing sulfuric acid production facility, the process is simple, the operation is convenient, safe and environment-friendly, the problem that the sulfur-containing waste is difficult to accumulate and treat is solved, new benefits can be generated by relying on the sulfuric acid production device, and the sulfuric acid production cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of sulfur-containing waste treatment, and more specifically, the present invention relates to a method for treating sulfur-containing waste. Background Art

[0002] As an important part of the circular economy, solid waste sorting and resource utilization have gradually received attention from the country and the market in recent years. Since sulfur-containing solid waste contains sulfur and heavy metal elements, it not only occupies land and pollutes water sources and air, but also easily spontaneously combusts in the air to generate oxides, and forms acid rain when it encounters water vapor to pollute the ecological environment. Most sulfur-containing wastes are in a state of stacking or low-value utilization, resulting in a waste of resources. Therefore, there is a large room for development in the harmless disposal and coordinated resource utilization of domestic sulfur-containing solid wastes.

[0003] There are many studies on the disposal methods of sulfur-containing solid waste, which are mainly divided into deep burial, incineration, chemical treatment and other categories. The deep burial method is to bury the sulfur-containing solid waste in a different place. It not only costs a lot to build underground facilities, but also cannot prevent its slow release of SO2, and will also cause secondary pollution to the local environment. The ordinary incineration method is to send the sulfur-containing solid waste to an incinerator for incineration. The flue gas generated during the incineration process is released again to pollute the ecological environment. This method is prone to unsatisfactory treatment results due to incomplete combustion, unstable concentration of pollutant release, and difficult to control production process parameters. There are many types of chemical treatment methods, most of which are complex and have high treatment costs. If the wastewater generated during the treatment process is not properly protected, there is also the possibility of secondary pollution. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these purposes and other advantages of the present invention, a method for treating sulfur-containing waste is provided, comprising the following steps:

[0006] Step 1: Pretreatment of sulfur-containing waste: Mix the ore raw material and the sulfur-containing waste evenly, naturally pile them up to evaporate the water, and sieve them through a screen to obtain a mixed material. The material that does not pass through the screen is crushed and reused;

[0007] Step 2, high-temperature combustion: The mixed material is transported to the incinerator, and the mixed material and air are burned together to produce SO2 furnace gas, which is pumped into the waste heat recovery device, and the ash remaining in the furnace is discharged and collected from the slag discharge port at the bottom of the furnace;

[0008] Step 3: Heat recovery of furnace gas: The furnace gas enters the waste heat recovery device to recover heat energy, and the furnace gas after cooling enters the purification device;

[0009] Step 4: Purification of furnace gas: The furnace gas enters the purification device, where the ash and acid mist in the furnace gas are removed by gravity, pickling and electric field action, and then enters the conversion device after humidification, cooling and drying;

[0010] Step 5: Conversion and absorption of furnace gas: The furnace gas enters the conversion device, mixes with air, and is catalyzed by vanadium catalysts in different conversion layers to become conversion gas. The conversion gas enters the absorption tower and is absorbed by water or sulfuric acid to generate finished acid. The tail gas after conversion and absorption enters the tail gas treatment device and is discharged after being cleaned and meeting the standards.

[0011] Preferably, in step 1, the sulfur-containing waste is sulfur-containing solid waste, the main components of which are coal tar, crude benzene, sulfur, ammonium sulfate, Al, Ca and Mg; and the ore raw material is raw ore composed of iron sulfide and quartz.

[0012] Preferably, the ore raw material is pyrite.

[0013] Preferably, in the step 1, the mass ratio of the ore raw material to the sulfur-containing waste is 1:0.05-5; the water is evaporated by natural stacking to a water content of 4-15%; and the screen size is ≤10 mm.

[0014] Preferably, in step 2, the furnace temperature in the incinerator is 700-1000° C., the furnace top pressure is ≤500 Pa, and the furnace bottom pressure is 10-15 KPa; and the residual oxygen content of the generated furnace gas is ≤3 mol%.

[0015] Preferably, in step 2, the conveying speed of the mixed material to the incinerator is 14-15 t / h.

[0016] Preferably, in step three, the waste heat recovery device is a waste heat boiler, which uses boiler circulating water to reduce the furnace gas temperature to 400-500° C., generating saturated steam which is transported to the power generation device.

[0017] Preferably, in step 4, the furnace gas enters the purification device and the temperature drops to 150-300°C.

[0018] Preferably, in step four, the ash and acid mist in the furnace gas are removed by gravity, acid washing and electric field action, specifically: gravity dust removal by a cyclone device, countercurrent washing dust removal with a dilute acid concentration of 2 to 10wt%, and multi-stage series electric field action mist removal with a secondary voltage of 30 to 80kV and a secondary current of 50 to 200mA.

[0019] Preferably, in step 4, drying is performed using sulfuric acid with a concentration of 90 to 100 wt %; and the furnace gas temperature at the outlet of the purification device at the tail end is not higher than 50° C.

[0020] Preferably, in step five, the temperature in the conversion device is 400° C. to 600° C.; and 3 to 6 conversion layers are provided in the conversion device.

[0021] Preferably, in step 5, the tail gas treatment device uses an activated carbon catalyst process to clean the tail gas, and the content of sulfur oxides in the tail gas after cleaning is less than 200 mg / m 3 , meet the environmental protection requirements of pollutant emissions.

[0022] Preferably, in step five, the furnace gas can be converted and absorbed multiple times, specifically: the furnace gas enters the conversion device, is mixed with air, and is catalyzed by a vanadium catalyst in at least one conversion layer to become a conversion gas, the conversion gas enters the absorption tower and is absorbed by water or sulfuric acid to generate a finished acid, the absorbed gas enters the conversion device again and is catalyzed by a vanadium catalyst in at least one remaining conversion layer to become a conversion gas, the conversion gas enters the absorption tower and is absorbed by water or sulfuric acid to generate a finished acid, and the exhaust gas after 1 to 3 cycles enters the exhaust gas treatment device and is discharged after being cleaned and meeting the standards.

[0023] Preferably, the step 1 is replaced by: mixing the ore raw material and the sulfur-containing waste evenly, naturally stacking to evaporate water, sieving through a sieve, placing in an acoustic resonance tank, setting the vibration frequency to 50-70 Hz, treating for 20-50 min, and then heating the material to 90-110° C. and keeping it warm for 20-40 min under a vacuum degree of 50-150 Pa, heating it to 120-140° C. and keeping it warm for 10-30 min, cooling it to 90-110° C. and keeping it warm for 20-40 min, and naturally cooling it to room temperature to obtain a mixed material.

[0024] The present invention has at least the following beneficial effects:

[0025] (1) Most sulfuric acid chemical production enterprises produce by high-temperature incineration of sulfur sources. In order to have a relatively stable and low-cost power supply and recycle heat energy, most enterprises have invested in the establishment of power generation facilities that are compatible with production, and have established corresponding environmental protection facilities in accordance with relevant national regulations, reserving a certain amount of processing margin, and have the ability to synergistically dispose of sulfur-containing substances. The present invention uses a process method for synergistically treating sulfur-containing wastes with the help of a sulfuric acid production line. The method has the characteristics of convenient treatment and large disposal capacity, and has good technical and economic benefits.

[0026] (2) The treatment process of the sulfur-containing waste of the present invention is clean, safe, and has mature technology. The low-temperature catalyst catalytic tail gas desulfurization process effectively controls the environmental pollution caused by the discharge of residual gas in the tower.

[0027] (3) Taking advantage of the raw material processing characteristics of sulfuric acid production enterprises, without changing the production process conditions and process parameters, sulfur-containing waste is mixed and screened, recovered and crushed to make the uneven sulfur-containing waste solids reach a particle size of less than 10 mm and mix them evenly with the ore raw materials. The concentration of pollutants released fluctuates little, and the amount of SO2 generated after combustion is stable, ensuring the stability of tail gas emissions after the finished product is generated.

[0028] (4) Compared with solid waste and garbage treatment furnaces such as garbage incinerators, sulfuric acid production has a high incineration temperature, mature technology, and complete production line facilities. The combustion products of sulfur-containing waste are gas and solid. The gas is efficiently absorbed as sulfuric acid-related products, and the solid and ore raw material by-products (iron oxides and silicate minerals) are recycled as acid production by-products and no longer generate any pollution sources or waste.

[0029] (5) The present invention enables efficient utilization of sulfur-containing wastes with low processing costs. The heat energy released by incineration is used to generate electricity, the sulfur element is converted into sulfuric acid products, and other metal elements are mixed with by-products for recycling. No additional equipment is required, the operating cost is low, and additional economic benefits are generated.

[0030] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0033] The sulfur-containing waste used in the following examples is sulfur-containing solid waste generated in the process of metallurgical coke production, including coal tar, crude benzene, sulfur, ammonium sulfate, Al, Ca and Mg.

[0034] Example 1

[0035] A method for treating sulfur-containing waste comprises the following steps:

[0036] Step 1: Pretreatment of sulfur-containing waste: Mix sulfur concentrate and sulfur-containing waste in a mass ratio of 1:4, naturally pile and evaporate until the water content reaches 8%, pass through a 9mm sieve to obtain a mixed material, and the material that does not pass through the sieve is crushed and scattered for reuse;

[0037] Step 2, high-temperature combustion: The mixed material is continuously conveyed to the incinerator feed port at a feeding speed of 14t / h and enters the furnace. The furnace bottom fan operates at a frequency of 40Hz, and the air is introduced to burn with the mixed material at 820℃ to produce SO2 furnace gas. The furnace top pressure is 450Pa, and the furnace bottom pressure is 13KPa. The rear-end fan draws the generated furnace gas into the rear-end device, and the residual ash in the furnace is discharged from the furnace bottom slag outlet and collected in the pile shed, and then sold out as a by-product;

[0038] Step 3: Heat recovery of furnace gas: The furnace gas first enters the waste heat boiler, and the boiler circulating water is used to reduce the furnace gas temperature to 450°C, generating saturated steam that is transported to the steam turbine for power generation. The cooled furnace gas enters the purification device through the pipeline;

[0039] Step 4, purification of furnace gas: the temperature of the furnace gas entering the purification device is reduced to 180°C, and the ash and acid mist in the furnace gas are removed by gravity dust removal of a cyclone device, countercurrent washing with 3wt% dilute sulfuric acid, and multi-stage series electric field demisting with a secondary voltage of 50kV and a secondary current of 100mA. The temperature of the furnace gas after leaving the purification device is 48°C, and after being dried with 94wt% concentrated sulfuric acid, it is sucked into the conversion device by a fan;

[0040] Step 5: Conversion and absorption of furnace gas: The furnace gas is drawn into the conversion device by the fan, the temperature in the conversion device is 500°C, the valve in the pipeline is opened to introduce air and furnace gas into the conversion device together, and the converted gas is catalyzed by the vanadium catalyst in the 1st, 2nd and 3rd conversion layers in turn to be converted gas, and the converted gas enters the absorption tower and is absorbed by 98wt% sulfuric acid to generate finished acid. After treatment for 1h, the concentration of the finished acid is 98.1wt%. The tail gas after conversion and absorption enters the tail gas treatment device, and the tail gas is cleaned by the activated carbon catalyst process to generate dilute acid in one step. After treatment, the sulfur oxides in the exhaust gas discharged are less than 200mg / m 3 , meet the environmental protection requirements of pollutant emissions.

[0041] Example 2

[0042] A method for treating sulfur-containing waste comprises the following steps:

[0043] Step 1: Pretreatment of sulfur-containing waste: Mix sulfur concentrate and sulfur-containing waste in a mass ratio of 1:4.5, naturally stack and evaporate until the water content reaches 7.8%, pass through a 9mm sieve to obtain a mixed material, and convey the mixed material to a silo by a belt transmission device for temporary storage. The material that does not pass through the sieve is crushed and scattered for reuse;

[0044] Step 2, high-temperature combustion: The mixed material is continuously conveyed to the incinerator feed port at a feeding speed of 14t / h and enters the furnace. The furnace bottom fan operates at a frequency of 40Hz, and the air is introduced to burn with the mixed material at 800℃ to produce SO2 furnace gas. The furnace top pressure is 430Pa, and the furnace bottom pressure is 13.5KPa. The rear-end fan draws the generated furnace gas into the rear-end device, and the residual ash in the furnace is discharged from the furnace bottom slag outlet and collected in the pile shed, and then sold out as a by-product;

[0045] Step 3: Heat recovery of furnace gas: The furnace gas first enters the waste heat boiler, and the boiler circulating water is used to reduce the furnace gas temperature to 440°C, generating saturated steam that is transported to the steam turbine for power generation. The cooled furnace gas enters the purification device through the pipeline;

[0046] Step 4, purification of furnace gas: the temperature of the furnace gas entering the purification device is reduced to 175°C, and the ash and acid mist in the furnace gas are removed by gravity dust removal of a cyclone device, countercurrent washing with 4wt% dilute sulfuric acid, and multi-stage series electric field demisting with a secondary voltage of 50kV and a secondary current of 100mA. The temperature of the furnace gas after leaving the purification device is 48°C, and after being dried with 93.8wt% concentrated sulfuric acid, it is sucked into the conversion device by a fan;

[0047] Step 5, conversion and absorption of furnace gas: the furnace gas is drawn into the conversion device by the fan, the temperature in the conversion device is 500°C, the valve in the pipeline is opened to introduce air and furnace gas into the conversion device together, and the converted gas is catalyzed by the vanadium catalyst in the 1st to 5th conversion layers to be converted gas, and the converted gas enters the absorption tower and is absorbed by 97.5wt% sulfuric acid to generate finished acid. After 1h of treatment, the concentration of the finished acid reaches 98.2wt%. The tail gas after conversion and absorption enters the tail gas treatment device, and the tail gas is cleaned by the activated carbon catalyst process to generate dilute acid in one step. After treatment, the sulfur oxides in the discharged waste gas are less than 200mg / m 3 , meet the environmental protection requirements of pollutant emissions.

[0048] Example 3

[0049] The present embodiment provides a method for treating sulfur-containing wastes, which differs from the embodiment 1 only in that the pretreatment method of the sulfur-containing wastes in step 1 is different. The pretreatment of the sulfur-containing wastes in the present embodiment is as follows: the sulfur concentrate and the sulfur-containing wastes are uniformly mixed in a mass ratio of 1:4, naturally piled and evaporated to a water content of 8%, passed through a 9 mm sieve, placed in an acoustic resonance tank, the vibration frequency is set to 60 Hz, and treated for 30 minutes, then the material is heated to 100°C and kept warm for 30 minutes under a vacuum degree of 100 Pa, heated to 130°C and kept warm for 20 minutes, cooled to 100°C and kept warm for 30 minutes, and naturally cooled to room temperature to obtain a mixed material; the remaining steps are the same as those in the embodiment 1, and the finished acid concentration reaches 99.0wt% after treatment for 1 hour. In this embodiment, before the mixed material is incinerated, acoustic resonance is used to make the material mix more evenly, and then the material is subjected to vacuum low-temperature segmented heat treatment, which is beneficial to the subsequent high-temperature combustion stage of the material, and the combustion is more complete. The S therein is more easily converted into SO2, thereby improving the combustion conversion efficiency of the mixed material, increasing the SO2 content in the furnace gas, and finally obtaining a higher concentration of the finished acid.

[0050] Example 4

[0051] The present embodiment provides a method for treating sulfur-containing wastes, which differs from the embodiment 1 only in that the pretreatment method of the sulfur-containing wastes in step 1 is different. The pretreatment of the sulfur-containing wastes in the present embodiment is as follows: the sulfur concentrate and the sulfur-containing wastes are uniformly mixed in a mass ratio of 1:4, naturally piled and evaporated to a water content of 8%, passed through a 9 mm sieve, placed in an acoustic resonance tank, the vibration frequency is set to 60 Hz, and treated for 30 minutes to obtain a mixed material; the remaining steps are the same as in the embodiment 1, and the finished acid concentration reaches 98.5wt% after 1 hour of treatment.

[0052] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for treating sulfur-containing waste, characterized in that: The following steps are involved: Step 1: Pretreatment of sulfur-containing waste: Mix the ore raw material and the sulfur-containing waste evenly, naturally pile them up to evaporate the water, and sieve them through a screen to obtain a mixed material. The material that does not pass through the screen is crushed and reused; Step 2, high-temperature combustion: The mixed material is transported to the incinerator, and the mixed material and air are burned together to produce SO2 furnace gas, which is pumped into the waste heat recovery device, and the ash remaining in the furnace is discharged and collected from the slag discharge port at the bottom of the furnace; Step 3: Heat recovery of furnace gas: The furnace gas enters the waste heat recovery device to recover heat energy, and the furnace gas after cooling enters the purification device; Step 4: Purification of furnace gas: The furnace gas enters the purification device, where the ash and acid mist in the furnace gas are removed by gravity, pickling and electric field action, and then enters the conversion device after humidification, cooling and drying; Step 5: Conversion and absorption of furnace gas: The furnace gas enters the conversion device, mixes with air, and is catalyzed by vanadium catalysts in different conversion layers to become conversion gas. The conversion gas enters the absorption tower and is absorbed by water or sulfuric acid to generate finished acid. The tail gas after conversion and absorption enters the tail gas treatment device and is discharged after being cleaned and meeting the standards.

2. The method for treating sulfur-containing waste according to claim 1, characterized in that: In the step 1, the sulfur-containing waste is sulfur-containing solid waste; and the ore raw material is raw ore composed of iron sulfide and quartz.

3. The method for treating sulfur-containing waste according to claim 1, characterized in that: In the step 1, the mass ratio of the ore raw material to the sulfur-containing waste is 1:0.05-5; the water is evaporated by natural stacking to a water content of 4-15%; and the screen size is ≤10 mm.

4. The method for treating sulfur-containing waste according to claim 1, characterized in that: In the step 2, the furnace temperature in the incinerator is 700-1000° C., the furnace top pressure is ≤500 Pa, and the furnace bottom pressure is 10-15 KPa; the residual oxygen content of the generated furnace gas is ≤3 mol%.

5. The method for treating sulfur-containing waste according to claim 1, characterized in that: In step three, the waste heat recovery device is a waste heat boiler, which uses boiler circulating water to reduce the furnace gas temperature to 400-500°C, generating saturated steam which is transported to the power generation device.

6. The method for treating sulfur-containing waste according to claim 1, characterized in that: In the step 4, the ash and acid mist in the furnace gas are removed by gravity, acid washing and electric field action, specifically: gravity dust removal by a cyclone device, countercurrent washing dust removal with a dilute acid concentration of 2 to 10wt%, and multi-stage series electric field action mist removal with a secondary voltage of 30 to 80kV and a secondary current of 50 to 200mA.

7. The method for treating sulfur-containing waste according to claim 1, characterized in that: In the step 4, drying is performed using sulfuric acid with a concentration of 90 to 100 wt %; and the furnace gas temperature at the outlet of the tail end of the purification device is not higher than 50° C.

8. The method for treating sulfur-containing waste according to claim 1, characterized in that: In the step 5, the temperature in the conversion device is 400°C to 600°C.

9. The method for treating sulfur-containing waste according to claim 1, characterized in that: In the step 5, 3 to 6 conversion layers are arranged in the conversion device.

10. The method for treating sulfur-containing waste according to claim 1, characterized in that: In step 5, the tail gas treatment device uses an activated carbon catalyst process to clean the tail gas, and the content of sulfur oxides in the tail gas after cleaning is less than 200 mg / m 3 , meet the environmental protection requirements of pollutant emissions.