Fluorine-containing tail gas treatment equipment in low-temperature roasting process of rare earth concentrate
By designing fluorine-containing exhaust gas treatment equipment during the low-temperature roasting of rare earth concentrates, using spraying, washing and condensing technologies, the problems of difficult treatment of acid gases produced by concentrated sulfuric acid roasting and low fluorine recovery efficiency are solved, and efficient exhaust gas treatment is achieved and fluorine recycling reduces the cost of governance.
Patent Information
- Application Number
- CN202323490759.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-20
- Publication Date
- 2025-01-10
- Estimated Expiration
- 2033-12-20
AI Technical Summary
During the roasting process of concentrated sulfuric acid of rare earth concentrate, a large amount of mixed acid gases containing fluorine, silicon and sulfur are produced, which makes exhaust gas treatment difficult and costly, and the concentration of hydrofluoric acid recovery is relatively low.
A fluorine-containing exhaust gas treatment equipment for rare earth concentrate during low-temperature roasting is designed, including power wave scrubber, reverse nozzle, circulating water pipe, exhaust pipe, high-level dilute acid tank, electromister and other components. Through spraying, Wash, condense and circulate water treatment to reduce the flue gas temperature and improve the recycling of fluorine in the exhaust gas.
It effectively reduces the flue gas temperature, improves the efficiency of equipment use, realizes efficient recovery of acid gas, simplifies the process flow, reduces the cost of treatment, and meets the fluoride concentration limit in the "Rare Earth Industrial Pollutant Emission Standard".
Smart Images
Figure CN222324741U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of environmental protection of rare earth concentrate roasting tail gas treatment, and specifically relates to fluorine-containing tail gas treatment equipment in the process of low-temperature roasting of rare earth concentrate. Background Art
[0002] At present, rare earth concentrate is decomposed by roasting with concentrated sulfuric acid. The process has high decomposition temperature and high consumption of concentrated sulfuric acid. A large amount of mixed acidic gas containing fluorine, silicon and sulfur is generated during the roasting and decomposition process. In addition, a large amount of acidic tail gas needs to be sprayed and absorbed by a variety of combined processes. The tail gas treatment is difficult and costly, and the concentration of recovered hydrofluoric acid is low. Utility Model Content
[0003] The utility model aims to provide a fluorine-containing tail gas treatment equipment during the low-temperature roasting of rare earth concentrate, which can reduce the flue gas temperature, improve the equipment use efficiency, and recycle the fluorine in the tail gas.
[0004] The technical solution is as follows:
[0005] The fluorine-containing tail gas treatment equipment during the low-temperature roasting process of rare earth concentrate includes: a power wave scrubber, a reverse spray pipe, a circulating water pipe, a tail gas pipe, a high-level dilute acid tank, and an electric demister. The side of the power wave scrubber is provided with a first tail gas inlet and a first spray water inlet, the top is provided with a first tail gas outlet, the bottom is connected with a first hydrofluoric acid circulation tank, a first nozzle is provided inside, the first tail gas inlet is located above the first spray water inlet, and the first nozzle is connected to the first spray water inlet; the inside of the reverse spray pipe is provided with a second nozzle, the top is provided with a second tail gas inlet, the bottom is provided with a second tail gas outlet, and the side is provided with a second spray water inlet. The second nozzle is connected to the second spray water inlet, and the second exhaust gas outlet is connected to the first exhaust gas inlet; the third exhaust gas inlet is arranged at the bottom of the electric precipitator, the third exhaust gas outlet is arranged at the top, and a recovery port is arranged at the bottom, and the recovery port is connected to the first hydrofluoric acid circulation tank through a circulating water pipe; the exhaust pipe is connected to the second exhaust gas inlet, and the first exhaust gas outlet is connected to the third exhaust gas inlet through the exhaust pipe; the circulating water pipe is connected between the high-level dilute acid tank and the first hydrofluoric acid circulation tank, and the circulating water pipe led out from the high-level dilute acid tank is respectively connected to the first spray water inlet and the second spray water inlet, and the circulating water pipe is provided with a main circulation pump, and electric valves are respectively provided on both sides of the main circulation pump.
[0006] Furthermore, the tail gas pipe is provided with an induced draft fan.
[0007] Furthermore, it also includes: a packed washing tower, a packed washing tower having a packed layer and a third nozzle arranged inside, the third nozzle being located at the upper part of the packed layer, a fourth exhaust gas outlet being arranged at the top, a third spray water inlet being arranged at the side, a fourth exhaust gas inlet being arranged at the lower part, and a second hydrofluoric acid circulation tank being arranged at the bottom; the second hydrofluoric acid circulation tank is connected to the first hydrofluoric acid circulation tank through a circulating water pipe, the third nozzle is connected to the second hydrofluoric acid circulation tank through a circulating water pipe, and the circulating water pipe is provided with an auxiliary circulating pump; the exhaust pipe led out from the first exhaust gas outlet is connected to the fourth exhaust gas inlet, and the exhaust pipe led out from the fourth exhaust gas outlet is connected to the third exhaust gas inlet of the electric precipitator.
[0008] Furthermore, a plurality of packed washing towers connected in series are arranged at the rear of the dynamic wave scrubber, the exhaust pipe leading out of the fourth exhaust gas outlet of the previous packed washing tower is connected to the fourth exhaust gas inlet of the next packed washing tower, the exhaust pipe leading out of the fourth exhaust gas outlet of the last packed washing tower is connected to the third exhaust gas inlet of the electric precipitator, the recovery port of the electric precipitator is connected to the second hydrofluoric acid circulation tank of the last packed washing tower through a circulating water pipe, and the plurality of second hydrofluoric acid circulation tanks are connected in series in sequence through the circulating water pipe.
[0009] Furthermore, the bottoms of the first hydrofluoric acid circulation tank and the second hydrofluoric acid circulation tank are connected to the sedimentation tank through pipelines.
[0010] Furthermore, it also includes: a compression cylinder, a dilute acid microporous filter, an air pipeline connected to the compression cylinder, the compression cylinder is connected to the upper part of the dilute acid microporous filter through the air pipeline, and the dilute acid microporous filter is connected to the tail pipe through the air pipeline; the side of the dilute acid microporous filter is connected to the first hydrofluoric acid circulation tank through a circulating water pipe, and a secondary circulation pump is arranged in the circulating water pipe between the dilute acid microporous filter and the first hydrofluoric acid circulation tank; the bottom of the dilute acid microporous filter is connected to the acid storage tank through a pipeline, and electric valves are respectively arranged on both sides of the secondary circulation pump.
[0011] Furthermore, it also includes: a filtrate storage tank, the filtrate storage tank is connected to the first hydrofluoric acid circulation tank through a pipeline, the outlet of the first hydrofluoric acid circulation tank is connected to a delivery pipe, and the delivery pipe is provided with a delivery pump.
[0012] Furthermore, it also includes: a heat exchanger, one side of the heat exchanger is connected to the circulating water pipe of the packing washing tower, and the other side is respectively connected to the water supply pipe and the return pipe.
[0013] Compared with the prior art, the utility model has the following advantages:
[0014] 1. Reduce the flue gas temperature and improve the efficiency of equipment use.
[0015] Compared with the existing process, the utility model produces tail gas mainly containing fluorine when the temperature of rare earth concentrate roasting with concentrated sulfuric acid is 200-250°C, and the main components of the tail gas are HF, SiF4, CO2, SO2, water vapor and a small amount of dust and other gases.
[0016] 2. The process flow is relatively simple and easy to realize automatic control.
[0017] 3. Recycle fluorine in tail gas with high yield to achieve acid gas recovery. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 The utility model is a structural principle diagram of the fluorine-containing tail gas treatment equipment in the low-temperature roasting process of the rare earth concentrate. DETAILED DESCRIPTION
[0019] The following description sufficiently illustrates specific embodiments of the present invention to enable those skilled in the art to practice and reproduce the same.
[0020] like Figure 1 The figure shows the structural principle diagram of the fluorine-containing tail gas treatment equipment during the low-temperature roasting process of the rare earth concentrate in the utility model.
[0021] The equipment for treating fluorine-containing tail gas during the low-temperature roasting process of rare earth concentrate includes: a dynamic wave scrubber 1, a reverse jet pipe 2, a circulating water pipe 3, a tail gas pipe 4, a high-level dilute acid tank 5, and an electrostatic precipitator 6.
[0022] The side of the power wave scrubber 1 is provided with a first tail gas inlet and a first spray water inlet, and the top is provided with a first tail gas outlet, the first tail gas inlet is located above the spray water inlet, the bottom of the power wave scrubber 1 is connected to a first hydrofluoric acid circulation tank 11, and the inside of the power wave scrubber 1 is provided with a first nozzle, and the first nozzle is connected to the first spray water inlet. The first hydrofluoric acid circulation tank 11 is used to store the acid solution after washing the tail gas.
[0023] A second nozzle is arranged inside the reverse spray pipe 2, a second exhaust gas inlet is arranged on the top, a second exhaust gas outlet is arranged on the bottom, a second spray water inlet is arranged on the side, and the second nozzle inside is connected to the second spray water inlet; the second exhaust gas outlet is connected to the first exhaust gas inlet.
[0024] The electrostatic precipitator 6 is provided with a third tail gas inlet at the bottom, a third tail gas outlet at the top, and a recovery port at the bottom, which is connected to the first hydrofluoric acid circulation tank 11 through the circulation water pipe 3; the tail gas is removed from particulate matter, sulfuric acid mist, etc. in the electrostatic precipitator 6.
[0025] The tail gas pipe 4 is connected to the second tail gas inlet, the first tail gas outlet is connected to the third tail gas inlet through the tail gas pipe 4, and the tail gas pipe 4 connected to the third tail gas outlet leads the purified tail gas out. The tail gas pipe 4 is provided with an induced draft fan for extracting the tail gas, and at the same time, a negative pressure is formed inside the power wave scrubber 1, the reverse spray pipe 2, and the electric demister 6.
[0026] The high-level diluted acid tank 5 is used to store the acid solution after washing the tail gas, and the acid solution can be recycled; the circulating water pipe 3 is connected between the high-level diluted acid tank 5 and the first hydrofluoric acid circulation tank 11, and the circulating water pipe 3 drawn from the high-level diluted acid tank 5 is respectively connected to the first spray water inlet and the second spray water inlet, and the circulating water pipe 3 is provided with a main circulation pump 31, and electric valves are respectively provided on both sides of the main circulation pump 31. In order to adjust the concentration of the acid solution, the high-level diluted acid tank 5 is connected to the water supply pipe 9.
[0027] In order to further purify the tail gas, a plurality of packed washing towers 8 connected in series are arranged at the rear of the power wave scrubber 1. A packing layer and a third nozzle are arranged inside the packed washing tower 8. The third nozzle is located at the upper part of the packing layer. A fourth tail gas outlet is arranged at the top, a third spray water inlet is arranged at the side, a fourth tail gas inlet is arranged at the bottom, and a second hydrofluoric acid circulation tank 81 is arranged at the bottom. The second hydrofluoric acid circulation tank 81 is connected to the first hydrofluoric acid circulation tank 11 through a circulating water pipe 3, and the third nozzle is connected to the second hydrofluoric acid circulation tank 81 through a circulating water pipe 3. The circulating water pipe 3 is provided with an auxiliary circulating pump 82 for the spray water circulation inside the packed washing tower 8. The tail gas pipe 4 led out from the first tail gas outlet is connected to the fourth tail gas inlet, and the tail gas pipe 4 led out from the fourth tail gas outlet is connected to the third tail gas inlet of the electric demister 6.
[0028] The bottoms of the first hydrofluoric acid circulation tank 11 and the second hydrofluoric acid circulation tank 81 are connected to a sedimentation tank 84 through pipelines for discharging sediments.
[0029] In order to control the temperature of the spray liquid and the tail gas, the packed washing tower 8 is provided with a heat exchanger 83, one side of the heat exchanger 83 is connected to the circulating water pipe 3 of the packed washing tower 8, and the other side is respectively connected to the water supply pipe 9 and the return water pipe 7.
[0030] In this preferred embodiment, three packed washing towers 8 are connected in series, the tail gas pipe 4 leading out of the fourth tail gas outlet of the previous stage packed washing tower 8 is connected to the fourth tail gas inlet of the next stage packed washing tower 8, the tail gas pipe 4 leading out of the fourth tail gas outlet of the last stage packed washing tower 8 is connected to the third tail gas inlet of the electric precipitator 6, and the recovery port of the electric precipitator 6 is connected to the second hydrofluoric acid circulation tank 81 of the last stage packed washing tower 8 through the circulating water pipe 3, and the three second hydrofluoric acid circulation tanks 81 are connected in series in sequence through the circulating water pipe 3.
[0031] In order to prevent the tail gas pipe 4 from being blocked, a compression cylinder 21 and a dilute acid microporous filter 22 are provided, an air pipeline 20 is connected to the compression cylinder 21, and the compression cylinder 21 is connected to the upper part of the dilute acid microporous filter 22 through the air pipeline 20, and the dilute acid microporous filter 22 is connected to the tail gas pipe 4 through the air pipeline 20, and the tail gas pipe 4 is purged by high-pressure air to prevent the tail gas pipe 4 from being blocked. The side of the dilute acid microporous filter 22 is connected to the first hydrofluoric acid circulation tank 11 through the circulating water pipe 3, and a secondary circulation pump 32 is provided in the circulating water pipe 3 between the dilute acid microporous filter 22 and the first hydrofluoric acid circulation tank 11; the bottom of the dilute acid microporous filter 22 is connected to the acid storage tank 33 through a pipeline. Electric valves are provided on both sides of the secondary circulation pump 32 to control the flow direction of the acid solution in the circulating water pipe 3 on the main circulation pump 31 and the secondary circulation pump 32. Part of the cleaning liquid in the first hydrofluoric acid circulation tank 11 is sent to the dilute acid microporous filter 22 through the secondary circulation pump 32 , and then sent to the acid storage tank 33 through the dilute acid microporous filter 22 .
[0032] In order to recover hydrofluoric acid, a filtrate storage tank 23 is provided. The filtrate storage tank 23 is connected to the first hydrofluoric acid circulation tank 11 through a pipeline. The outlet of the first hydrofluoric acid circulation tank 11 is connected to a delivery pipe, and a delivery pipe is provided with a delivery pump. The hydrofluoric acid melt in the first hydrofluoric acid circulation tank 11 is stored in the filtrate storage tank 23. The delivery pump extracts from the filtrate storage tank 23 and delivers it through the delivery pipe. The filtrate storage tank 23 is connected to the dilute acid microporous filter 22 through a pipeline, and the sediment is stirred regularly to prevent the delivery pipe from being blocked. The total acidity of the hydrofluoric acid in the filtrate storage tank 23 is ≥20%, SO4 2- Content <1%.
[0033] The flue gas with a temperature of about 230°C from the rare earth roasting first enters the reverse nozzle 2, where the flue gas meets the washing liquid sprayed from bottom to top, collides to form a foam column, which fully washes the harmful impurities and dust in the flue gas. At the same time, the water in the washing liquid evaporates, quickly reducing the high-temperature flue gas to about 78°C; it is flushed with a large amount of washing liquid through the dynamic wave scrubber 1 to remove most of the solid particles and harmful components in the gas flow.
[0034] After the flue gas is washed and cooled to about 78°C by the power wave scrubber 1, it enters the packed scrubber 8 for gas cooling and water vapor condensation. In the packed scrubber 8, the cold scrubbing liquid flows from top to bottom through the packing layer, and contacts the flue gas washed by the power wave scrubber 1 from bottom to top in the packing layer. Due to the condensation of water vapor in the gas, the scrubbing liquid increases, and the excess condensed water is sent back to the power wave scrubber 1. In the circulation loop of the packed scrubber 8, the heat exchanger 83 cools the circulating scrubbing liquid to remove the heat generated by the gas cooling during the purification process. After the flue gas is washed by the packed scrubber 8, the flue gas temperature is about 40°C, and the flue gas enters the subsequent packed scrubber 8 for further gas cooling and water vapor condensation. At this time, the water vapor, SiF4 and HF gas in the flue gas will be condensed, and the condensate is collected in the second hydrofluoric acid circulation tank 81 to obtain a hydrofluoric acid solution.
[0035] Due to the high concentration of hydrofluoric acid obtained by condensation, the saturated vapor partial pressure of HF in the flue gas is high. After two-stage cooling and condensation, the concentration of HF in the flue gas is still much higher than 5 mg / m 3 The lower the concentration of circulating hydrofluoric acid, the lower the saturated vapor partial pressure of HF in the flue gas, and the lower its content. Therefore, in order to recover the HF in the flue gas, the flue gas needs to be washed with water; finally, it is automatically connected in series to the first hydrofluoric acid circulation tank 11 according to the liquid level to ensure that the hydrofluoric acid concentration is 20%. After the flue gas is washed with three levels of water, it is further removed by the electrostatic precipitator 6 to remove particulate matter, sulfuric acid mist, etc. in the flue gas, ensuring that the fluoride concentration in the flue gas is less than 5mg / m 3 . Thus, the emission concentration limit of the "roasting process" process in the "Rare Earth Industry Pollutant Emission Standard" (GB26451-2011) is met.
[0036] The terms used in the present invention are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various forms without departing from the spirit or essence of the technical solution, it should be understood that the above embodiments are not limited to any of the aforementioned details, but should be widely interpreted within the spirit and scope defined by the attached claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the attached claims.
Claims
1. A fluorine-containing tail gas treatment equipment during low-temperature roasting of rare earth concentrate, characterized in that: include: A power wave scrubber, a reverse spray pipe, a circulating water pipe, a tail gas pipe, a high-level dilute acid tank, and an electric demister. The side of the power wave scrubber is provided with a first tail gas inlet and a first spray water inlet, the top is provided with a first tail gas outlet, the bottom is connected to a first hydrofluoric acid circulation tank, a first nozzle is provided inside, the first tail gas inlet is located above the first spray water inlet, and the first nozzle is connected to the first spray water inlet; a second nozzle is provided inside the reverse spray pipe, a second tail gas inlet is provided at the top, a second tail gas outlet is provided at the bottom, a second spray water inlet is provided on the side, and the second nozzle is connected to the second spray water inlet The second tail gas outlet is connected to the first tail gas inlet; the third tail gas inlet is arranged at the bottom of the electric precipitator, the third tail gas outlet is arranged at the top, and the bottom is arranged with a recovery port, and the recovery port is connected to the first hydrofluoric acid circulation tank through a circulating water pipe; the tail gas pipe is connected to the second tail gas inlet, and the first tail gas outlet is connected to the third tail gas inlet through the tail gas pipe; the circulating water pipe is connected between the high-level dilute acid tank and the first hydrofluoric acid circulation tank, and the circulating water pipe led out of the high-level dilute acid tank is respectively connected to the first spray water inlet and the second spray water inlet, and the circulating water pipe is provided with a main circulation pump, and electric valves are respectively provided on both sides of the main circulation pump.
2. The equipment for treating fluorine-containing tail gas during low-temperature roasting of rare earth concentrate according to claim 1, characterized in that: The tail gas pipe is provided with an induced draft fan.
3. The equipment for treating fluorine-containing tail gas during low-temperature roasting of rare earth concentrate according to claim 1, characterized in that: Also includes: A packed washing tower, wherein a packing layer and a third nozzle are arranged inside the packed washing tower, the third nozzle is located on the upper part of the packing layer, a fourth exhaust gas outlet is arranged on the top, a third spray water inlet is arranged on the side, a fourth exhaust gas inlet is arranged on the lower part, and a second hydrofluoric acid circulation tank is arranged on the bottom; the second hydrofluoric acid circulation tank is connected to the first hydrofluoric acid circulation tank through a circulating water pipe, the third nozzle is connected to the second hydrofluoric acid circulation tank through a circulating water pipe, and the circulating water pipe is provided with an auxiliary circulating pump; the exhaust pipe led out from the first exhaust gas outlet is connected to the fourth exhaust gas inlet, and the exhaust pipe led out from the fourth exhaust gas outlet is connected to the third exhaust gas inlet of the electric precipitator.
4. The equipment for treating fluorine-containing tail gas during low-temperature roasting of rare earth concentrate according to claim 3, characterized in that: A plurality of packed washing towers connected in series are arranged at the rear of the dynamic wave scrubber, the exhaust pipe led out from the fourth exhaust gas outlet of the previous packed washing tower is connected to the fourth exhaust gas inlet of the next packed washing tower, the exhaust pipe led out from the fourth exhaust gas outlet of the last packed washing tower is connected to the third exhaust gas inlet of the electric precipitator, the recovery port of the electric precipitator is connected to the second hydrofluoric acid circulation tank of the last packed washing tower through a circulating water pipe, and the plurality of second hydrofluoric acid circulation tanks are connected in series in sequence through the circulating water pipe.
5. The equipment for treating fluorine-containing tail gas during low-temperature roasting of rare earth concentrate according to claim 3, characterized in that: The bottoms of the first hydrofluoric acid circulation tank and the second hydrofluoric acid circulation tank are connected to the sedimentation tank through pipelines.
6. The equipment for treating fluorine-containing tail gas during low-temperature roasting of rare earth concentrate according to claim 3, characterized in that: Also includes: A compression cylinder and a dilute acid microporous filter, an air pipeline is connected to the compression cylinder, the compression cylinder is connected to the upper part of the dilute acid microporous filter through the air pipeline, and the dilute acid microporous filter is connected to the tail pipe through the air pipeline; the side of the dilute acid microporous filter is connected to the first hydrofluoric acid circulation tank through a circulating water pipe, and a secondary circulation pump is arranged in the circulating water pipe between the dilute acid microporous filter and the first hydrofluoric acid circulation tank; the bottom of the dilute acid microporous filter is connected to the acid storage tank through a pipeline, and electric valves are arranged on both sides of the secondary circulation pump.
7. The equipment for treating fluorine-containing tail gas during low-temperature roasting of rare earth concentrate according to claim 3, characterized in that: Also includes: The filtrate storage tank is connected to the first hydrofluoric acid circulation tank through a pipeline, the outlet of the first hydrofluoric acid circulation tank is connected to a delivery pipe, and the delivery pipe is provided with a delivery pump.
8. The equipment for treating fluorine-containing tail gas during low-temperature roasting of rare earth concentrate according to claim 3, characterized in that: Also includes: Heat exchanger: one side of the heat exchanger is connected to the circulating water pipe of the packed washing tower, and the other side is connected to the water supply pipe and the return pipe respectively.