CN112125416A - Technology for washing salt mud by lime flue gas method - Google Patents
Technology for washing salt mud by lime flue gas method Download PDFInfo
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- CN112125416A CN112125416A CN202010831437.5A CN202010831437A CN112125416A CN 112125416 A CN112125416 A CN 112125416A CN 202010831437 A CN202010831437 A CN 202010831437A CN 112125416 A CN112125416 A CN 112125416A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/24—Treatment of water, waste water, or sewage by flotation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
Abstract
The invention discloses a lime flue gas method salt mud washing process, which adopts an air floating type secondary sedimentation secondary washing process, and comprises the following steps: s1, air flotation separation: adjusting the solid-liquid ratio of the raw material salt slurry to 1: 3-1: 4, and introducing flue gas into the bottom of the first settling tank; s2, primary sedimentation: settling the slurry subjected to air floatation separation in a first settling tank, returning supernatant to an ore region for bittern collection after settling is finished, and allowing sludge to enter the next operation; s3, mixed rinsing: mixing and rinsing the sludge obtained in the step S2 and water in a second settling tank according to the volume ratio of 1: 4-1: 8, and adding a builder; s4, secondary sedimentation; s5, primary filtration; s6, washing for the first time; s7, secondary filtration; s8, washing for the second time; s9, filtering for three times. The lime flue gas method salt mud washing process has the advantages of high content of effective components, low water content, impurity content and COD value, low cost, environmental protection, low carbon economy and the like after being cleaned.
Description
Technical Field
The invention belongs to the field of environmental protection and the technical field of resource utilization of solid wastes, and particularly relates to a washing process of lime flue gas method salt mud.
Background
The brine purification process is a key process for improving the purity of refined salt products, reducing the content of impurities in salt and improving the whiteness of the salt products in the salt manufacturing industry. The salt slurry is a general name of various inorganic salts discharged in the process. Because the output is large and the components are complex, the direct discharge brings environmental pollution, and how to comprehensively utilize the waste water is a difficult problem which troubles the industry. The salt slurry mainly comprises calcium sulfate, calcium carbonate and magnesium hydroxide; in addition, a certain amount of water-soluble impurities such as sodium chloride and a small amount of organic impurities are mixed. The existing research shows that if the salt mud is thoroughly cleaned to reduce the impurity content, the effective components in the salt mud can be widely applied to the fields of power plant desulfurization, waste acid neutralization, chemical fillers and the like, solid waste is recycled, waste materials are changed into valuable, a certain environmental protection risk is avoided in the transportation and disposal process of the salt mud which is also thoroughly cleaned, the salt mud resource is recycled for salt manufacturing enterprises, the zero emission of the solid waste is gradually realized, and the market prospect is wide.
At present, most salt manufacturing enterprises adopt a lime flue gas method as a brine purification process, and the process principle is that the lime flue gas method is used as a brine purification process2+The reaction produces magnesium hydroxide precipitate, CO contained in the flue gas2With Ca in brine2+Reaction to form CaCO3Precipitating to remove Ca contained in brine2+、Mg2+Object of (SO)4 2－The mirabilite is separated in the salt and nitrate co-production process in a mirabilite form, and the reaction formula in the process flow is shown as follows.
Ca(OH)2+MgSO4→Mg(OH)2↓+CaSO4
Ca(OH)2+Na2SO4→2NaOH+CaSO4
2NaOH+CO2→Na2CO3+H2O
CaSO4+Na2CO3→CaCO3↓+Na2SO4
The process takes the exhausted flue waste gas of the thermal power plant as a raw material, can greatly reduce brine purification cost and simultaneously reduce carbon dioxide emission, but the salty mud component generated by the process is complex, the impurity content is high, in addition, the gas-liquid reaction cannot thoroughly lead to unreacted and sufficient NaOH in the salty mud, and the simple water washing process can partially remove soluble substances such as NaCl, NaOH and the like, but has the following problems: firstly, the salt mud surface is wrapped with partial organic impurities, and simple cleaning is not particularly effective; second, Mg (OH) in the salt mud2The existence of the salt slurry causes difficult dehydration and high water content of the salt slurry; thirdly, the content of effective components of the salt mud is influenced by unreacted NaOH; fourth, conventional mechanical agitation methods present the risk of introducing impurities.
At present, although the brine sludge water washing process is regarded by most salt manufacturing enterprises, due to the reasons of economy, technology and the like, the problems of single treatment means, incomplete cleaning and the like exist, the brine sludge water washing process cannot be popularized in a large area, and the subsequent application of the brine sludge is hindered. The invention provides an air-floating type secondary sedimentation secondary lime washing flue gas method salt mud washing process, which takes flue gas and water as main media, and adds a little builder to thoroughly wash the lime flue gas method salt mud, the salt mud after being washed has high content of effective components, low water content, salt content and COD value, the process is green and environment-friendly, low-carbon and economical, and a new way is developed for the efficient and low-cost comprehensive utilization of the subsequent salt mud.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art.
Therefore, the invention provides a washing process of lime flue gas method salt mud, which has the advantages of environmental protection, high content of effective components, low water content, low impurity content and low COD value.
According to the lime flue gas method salt mud washing process provided by the embodiment of the invention, an air-floating type secondary sedimentation secondary washing process is adopted, and the air-floating type secondary sedimentation secondary washing process comprises the following steps: s1, air flotation separation: adjusting the solid-liquid ratio of the raw material salt slurry to 1: 3-1: 4, and introducing flue gas into the bottom of the first settling tank; s2, primary sedimentation: settling the slurry subjected to air floatation separation in a first settling tank, returning supernatant to an ore region for bittern collection after settling is finished, and allowing sludge to enter the next operation; s3, mixed rinsing: mixing and rinsing the sludge obtained in the step S2 and water in a second settling tank according to the volume ratio of 1: 4-1: 8, and adding a builder; s4, secondary sedimentation: settling the slurry subjected to the mixed rinsing in the step S3 in a second settling tank, returning supernatant to an ore region for bittern collection after settling is finished, and allowing sludge to enter the next operation; s5, primary filtration: filtering and separating the sludge obtained in the step S4 to obtain a salt mud filter cake, and returning the filtrate and the supernatant obtained in the step S4 to the mining area for brine mining; s6, primary washing: transferring the salt mud filter cake obtained in the step S5 into a first washing tank, adding water with the salt mud volume ratio of 1: 4-1: 5, and introducing flue gas into the bottom of the first washing tank; s7, secondary filtration: filtering and separating the sludge obtained in the step S6 to obtain a salt mud filter cake, and transferring the filtrate into a second settling tank in the step S3 for recycling; s8, secondary washing: transferring the salt mud filter cake obtained in the step S5 into a second washing tank, adding water with the salt mud volume ratio of 1: 1-1: 2, and introducing flue gas into the bottom of the washing tank; 9. and (3) filtering for three times: and (5) filtering and separating the sludge obtained in the step S8 to obtain washed salt sludge, and transferring the filtrate to the second settling tank in the step S3 for recycling.
According to the lime flue gas method salt mud washing process provided by the embodiment of the invention, an air-floating type secondary sedimentation secondary washing process is adopted for washing and impurity removal, flue gas and water are used as main media, a small amount of builder is added, the lime flue gas method salt mud is thoroughly washed, the content of effective components of the salt mud is high after the washing is finished, the water content, the impurity content and the COD value are low, and the lime flue gas method salt mud washing process has the advantages of environmental friendliness, low carbon and economy and the like.
According to one embodiment of the invention, the flue gas is introduced in step S1 for a period of 20-30 min.
According to one embodiment of the invention, the flow rate of the flue gas in step S1 is controlled at 80m3/min～100m3/min。
According to one embodiment of the present invention, the settling time in step S2 is 30min to 40 min.
According to an embodiment of the present invention, the builder in the step S3 is any one of poly hydroxypropyl dimethyl ammonium chloride, poly diallyl dimethyl ammonium chloride, poly alkyl diallyl ammonium chloride, poly benzyl diallyl ammonium chloride, poly dihydroxy propyl dimethyl ammonium chloride, poly methacryloyloxyethyl trimethyl ammonium chloride, and poly methacrylamidopropyl trimethyl ammonium chloride.
According to an embodiment of the present invention, the mixed rinsing in the second settling tank in step S3 is performed by any one of convection mixed rinsing, shear mixed rinsing, and centrifugal mixed rinsing.
According to one embodiment of the invention, the salinity of the slurry liquid is controlled to be 12-15% in the mixed rinsing in the step S3.
According to an embodiment of the present invention, the pH value is controlled to be 8.5 to 9.5 in the mixed rinsing in step S3.
According to one embodiment of the present invention, in step S3, a builder is added in an amount of 0.01 to 0.02% by mass based on the mass of sludge.
According to one embodiment of the invention, the sedimentation in step S4 is for 30min to 40 min.
According to an embodiment of the invention, the maintaining time in step S6 is 10 min-15 min, and the flow rate of the flue gas is controlled to be 50-60 m3/min。
According to an embodiment of the invention, the maintaining time in the step S8 is 8 min-10 min, and the flow rate of the flue gas is controlled to be 20-30 m3/min。
According to one embodiment of the invention, the filtrate in the steps S7 and S9 is recycled to the system to be used as the S3 ingredient mixture, and the temperature of the flue gas is above 150 ℃.
According to an embodiment of the present invention, the filtering manner in step S5, step S7 and step S9 is any one of vacuum drum filtering, plate-and-frame filter pressing and horizontal spiral filtering.
According to one embodiment of the present invention, step S1, step S6, and step S8 employ air-floating agitation.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flow diagram of a process for scrubbing lime flue gas process salty mud according to an embodiment of the present invention.
Detailed Description
The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make several modifications to the present invention without departing from the principle of the present invention, and all changes and modifications that are equivalent to those made in the present invention are also within the scope of the appended claims.
The following describes in detail the washing process of lime flue gas method salt mud according to an embodiment of the present invention.
According to the lime flue gas method salt mud washing process, an air floating type secondary sedimentation secondary washing process is adopted.
As shown in fig. 1, specifically, according to the lime flue gas method salt mud washing process of the embodiment of the invention, the air-floating type secondary sedimentation secondary washing process comprises the following steps: s1, air flotation separation: adjusting the solid-liquid ratio of the raw material salt slurry to 1: 3-1: 4, and introducing flue gas into the bottom of the first settling tank; s2, primary sedimentation: settling the slurry subjected to air floatation separation in a first settling tank, returning supernatant to an ore region for bittern collection after settling is finished, and allowing sludge to enter the next operation; s3, mixed rinsing: mixing and rinsing the sludge obtained in the step S2 and water in a second settling tank according to the volume ratio of 1: 4-1: 8, and adding a builder; s4, secondary sedimentation: settling the slurry subjected to the mixed rinsing in the step S3 in a second settling tank, returning supernatant to an ore region for bittern collection after settling is finished, and allowing sludge to enter the next operation; s5, primary filtration: filtering and separating the sludge obtained in the step S4 to obtain a salt mud filter cake, and returning the filtrate and the supernatant obtained in the step S4 to the mining area for brine mining; s6, primary washing: transferring the salt mud filter cake obtained in the step S5 into a first washing tank, adding water with the salt mud volume ratio of 1: 4-1: 5, and introducing flue gas into the bottom of the first washing tank; s7, secondary filtration: filtering and separating the sludge obtained in the step S6 to obtain a salt mud filter cake, and transferring the filtrate into a second settling tank in the step S3 for recycling; s8, secondary washing: transferring the salt mud filter cake obtained in the step S5 into a second washing tank, adding water with the salt mud volume ratio of 1: 1-1: 2, and introducing flue gas into the bottom of the washing tank; s9, filtering for three times: and (5) filtering and separating the sludge obtained in the step S8 to obtain washed salt sludge, and transferring the filtrate to the second settling tank in the step S3 for recycling.
In other words, according to the lime flue gas method salt mud washing process of the embodiment of the invention, the raw material salt mud is subjected to air flotation separation in the step S1, primary sedimentation in the step S2, mixed rinsing in the step S3, secondary sedimentation in the step S4, primary filtration in the step S5, primary washing in the step S6, secondary filtration in the step S7, secondary washing in the step S8, and tertiary filtration in the step S9, so that the washed salt mud is obtained. That is to say, steps S1, S6, S8 adopt the air flotation separation washing mode, because salt mud contains some soluble impurity and a small amount of organic impurity, adopt the washing to remove soluble impurity, and air flotation separation can replace the organic impurity that salt mud surface adsorbs, reduces hard reunion, and bottom flue gas bubble is the torrent state and rises, can carry on the organic matter in the entrainment salt mud when air agitation is carried out to salt mud in the rising process. The flue gas is introduced into the steps S1, S6 and S8, and can be mixed with unreacted NaOH and a small amount of Mg (OH)2Reaction is carried out to generate Na2CO3And MgCO3Can be removed by secondary washing, so that the salty mud is easier to dehydrate and the water content of the salty mud is reduced. Further, the process willAnd (5) reusing the washing water obtained in the steps S7 and S9 in the system to be used as the ingredients in the step S3 for mixing use, and recycling water resources.
Therefore, according to the lime flue gas method salt mud washing process provided by the embodiment of the invention, the air-floating type secondary sedimentation secondary washing process is adopted for washing and impurity removal, flue gas and water are used as main media, a small amount of builder is added, the lime flue gas method salt mud is thoroughly washed, the content of effective components of the salt mud is high after the washing is finished, the water content, the impurity content and the COD value are low, the lime flue gas method salt mud washing process has the advantages of environmental friendliness, low carbon, economy and the like, and a new way is developed for the efficient and low-cost comprehensive utilization of the subsequent salt mud.
According to one embodiment of the invention, the flue gas is introduced in step S1 for a period of 20-30 min.
Further, the flow rate of the flue gas in step S1 was controlled to 80m3/min～100m3/min。
In some embodiments of the present invention, the settling time in step S2 is 30min to 40 min.
Optionally, the builder in step S3 is any one of poly (hydroxypropyl) dimethyl ammonium chloride, poly (diallyl) dimethyl ammonium chloride, poly (methyl alkyl) diallyl ammonium chloride, poly (benzyl) diallyl ammonium chloride, poly (dihydroxy) propyl dimethyl ammonium chloride, poly (methacryloyloxyethyl) trimethyl ammonium chloride, and poly (methacrylamidopropyl) trimethyl ammonium chloride. By adding the high molecular polymer builder, the builder can adsorb the surface of the salt slurry, change the charge distribution of the salt slurry, wet salt slurry particles, adsorb lipophilic groups of the builder on the surface of the salt slurry, solvate the hydrophilic groups as an aqueous medium, and rapidly expand the hydrophilic groups into a water body, so that the salt slurry particles are fully dispersed and are easier to wash and settle.
Further, the manner of the mixed rinsing in the second settling tank in step S3 is any one of convection mixed rinsing, shear mixed rinsing, and centrifugal mixed rinsing.
Preferably, the salinity of the slurry liquid is controlled to be 12-15% in the mixed rinsing in the step S3.
According to an embodiment of the present invention, the pH value is controlled to be 8.5 to 9.5 in the mixed rinsing in step S3. Namely, under the conditions that the salinity of the slurry is 12% -15%, and the pH value is 8.5-9.5, the high-molecular polymer builder is added, the builder can adsorb the surface of the salty mud, change the charge distribution of the salty mud, easily form an electric space position in a high salinity environment, play a role in stabilizing and dispersing, effectively reduce the interfacial tension between solid and liquid, wet salty mud particles, adsorb lipophilic groups of the builder on the surface of the salty mud, solvate the hydrophilic groups as an aqueous medium, and quickly expand the salty mud particles into a water body, so that the salty mud particles are fully dispersed and are easier to wash and settle.
Further, in step S3, a builder is added in an amount of 0.01 to 0.02% by mass based on the mass of the sludge.
Optionally, settling for 30min to 40min in step S4.
In some embodiments of the present invention, the maintaining time in step S6 is 10min to 15min, and the flow rate of the flue gas is controlled to be 50m to 60m3/min。
According to an embodiment of the invention, the maintaining time in the step S8 is 8 min-10 min, and the flow rate of the flue gas is controlled to be 20-30 m3/min。
Further, the filtrate obtained in the steps S7 and S9 is reused in the system and used as the ingredient of the step S3, and the temperature of the flue gas is above 150 ℃, so that the temperature of the washing water can be increased when the filtrate is used for washing in the system, the solubility of soluble impurities is increased, and the time and the water consumption of the washing process are reduced.
Optionally, the filtering manner in step S5, step S7 and step S9 is any one of vacuum drum filtration, plate-and-frame filter pressing and horizontal spiral filtration.
Preferably, the steps S1, S6 and S8 adopt air-floating stirring, so as to avoid the problem that the traditional mechanical stirring causes mechanical equipment corrosion in high salinity environment, thereby reducing the introduction of impurity ions such as Fe.
In summary, compared with the traditional water washing mode, the process of the lime flue gas method salt mud washing process provided by the embodiment of the invention has the advantages that the salt mud washing is more thorough and efficient, the quality of the washed salt mud is more excellent, in addition, the tail gas flue gas of a power plant and the washing water are effectively utilized, the salt mud refining cost is reduced, and the effects of energy conservation, emission reduction, circular economy and environment protection are achieved. Through the washing and refining of the salt mud, the impurity content of the salt mud can be effectively reduced, so that the salt mud can be widely applied to the fields of power plant desulfurization and waste acid neutralization, resources are recycled, and the backfilling and transportation treatment costs of salt mud injection wells are saved. The method has reasonable process, provides a new way for the pretreatment of the salty mud and other solid wastes, ensures the safety and reliability of the reaction process, provides favorable conditions for the separation and the refining of chemical reaction, provides experience for the solid waste treatment industry, and has simple process method, convenient preparation and safe and reliable process.
The present invention will be more fully understood by those skilled in the art from the following examples and comparative examples, but the present invention is not limited thereto.
Example 1
According to the washing process of the lime flue gas method salt mud, the lime flue gas method salt mud is washed by the following steps:
(1) air flotation separation: adjusting the solid-liquid ratio of raw material salt mud slurry to 1:3, introducing flue gas into the bottom of the first settling tank, maintaining for 30min, and controlling the flow rate of flue gas to 80m3/min。
(2) Primary sedimentation: and (4) settling the slurry subjected to air floatation separation in a first settling tank for 30min, returning the supernatant to the mining area after the settling is finished, and performing mud residue in the step (3).
(3) Mixing and rinsing: and (3) performing convective mixed rinsing on the sludge obtained in the last step and water in a second settling tank according to the volume ratio of 1:4, controlling the salinity of the sludge liquid to be 12-15% and the pH value to be 8.5-9.5, and adding poly-hydroxypropyl dimethyl ammonium chloride accounting for 0.01% of the mass of the sludge.
(4) Secondary sedimentation: and (4) settling the slurry mixed and rinsed in the step (3) in a second settling tank for 30min, returning the supernatant to the mining area to collect brine after the settling is finished, and feeding the sludge into the step (5).
(5) Primary filtration: and (4) carrying out plate-and-frame filter pressing separation on the sludge obtained in the step (4), obtaining a filter cake, entering the next step, and returning the filtrate and the supernatant obtained in the step (4) to the mining area for brine mining.
(6) Primary washing: transferring the salt mud filter cake obtained in the step (5) into a first washing tank, simultaneously adding water with the salt mud volume ratio of 1:4, introducing flue gas into the bottom of the washing tank, maintaining for 10min, and controlling the flow rate of the flue gas to be 50m3/min。
(7) Secondary filtration: and (4) carrying out plate-and-frame filter pressing separation on the sludge obtained in the step (6), obtaining a filter cake, entering the next step, and transferring the filtrate into the second settling tank in the step (2) for recycling.
(8) And (3) secondary washing: transferring the salt mud filter cake obtained in the step (5) into a second washing tank, simultaneously adding water with the salt mud volume ratio of 1:2, introducing flue gas into the bottom of the washing tank, maintaining for 10min, and controlling the flow rate of the flue gas to be 20m3/min。
(9) And (3) filtering for three times: and (3) carrying out plate-and-frame filter pressing separation on the sludge obtained in the step (8) to obtain washed salt mud, and transferring the filtrate into the second settling tank in the step (2) for recycling.
Example 2
According to the washing process of the lime flue gas method salt mud, the lime flue gas method salt mud is washed by the following steps:
(1) air flotation separation: adjusting the solid-liquid ratio of raw material salt mud slurry to 1:4, introducing flue gas into the bottom of the first settling tank, maintaining for 25min, and controlling the flow rate of flue gas to be 100m3/min。
(2) Primary sedimentation: and (4) settling the slurry subjected to air floatation separation in a first settling tank for 40min, returning the supernatant to the mining area after the settling is finished, and performing mud residue in the step (3).
(3) Mixing and rinsing: and (3) performing shear type mixing rinsing on the sludge obtained in the last step and water in a second settling tank according to the volume ratio of 1:8, controlling the salinity of the sludge liquid to be 12-15% and the pH value to be 8.5-9.5, and adding poly (dihydroxy propyl dimethyl ammonium chloride) accounting for 0.02% of the mass of the sludge.
(4) Secondary sedimentation: and (4) settling the slurry mixed and rinsed in the step (3) in a second settling tank for 40min, returning the supernatant to the mining area for brine mining after the settling is finished, and feeding the sludge into the step (5).
(5) Primary filtration: and (4) carrying out vacuum drum filtration separation on the sludge obtained in the step (4), obtaining a filter cake, entering the next step, and returning the filtrate and the supernatant obtained in the step (4) to the mining area for halogen mining.
(6) Primary washing: transferring the salt mud filter cake obtained in the step (5) into a first washing tank, simultaneously adding water with the salt mud volume ratio of 1:5, introducing flue gas into the bottom of the first washing tank, maintaining for 15min, and controlling the flow rate of the flue gas to be 60m3/min。
(7) Secondary filtration: and (4) carrying out vacuum drum filtration separation on the sludge obtained in the step (6), obtaining a filter cake, entering the next step, and transferring the filtrate into the second settling tank in the step (2) for recycling.
(8) And (3) secondary washing: transferring the salt mud filter cake obtained in the step (5) into a second washing tank, simultaneously adding water with the salt mud volume ratio of 1:1, introducing flue gas into the bottom of the washing tank, maintaining for 10min, and controlling the flow rate of the flue gas to be 30m3/min。
(9) And (3) filtering for three times: and (3) carrying out vacuum drum filtration separation on the sludge obtained in the step (8) to obtain washed salt mud, and transferring the filtrate into the second settling tank in the step (2) for recycling.
Example 3
According to the washing process of the lime flue gas method salt mud, the lime flue gas method salt mud is washed by the following steps:
(1) air flotation separation: adjusting the solid-liquid ratio of raw material salt mud slurry to 1:3, introducing flue gas into the bottom of the first settling tank, maintaining for 20min, and controlling the flow rate of flue gas to be 100m3/min。
(2) Primary sedimentation: and (4) settling the slurry subjected to air floatation separation in a first settling tank for 35min, returning the supernatant to the mining area for brine extraction after the settling is finished, and performing the step (3) on the sludge.
(3) Mixing and rinsing: and (3) performing convective mixed rinsing on the sludge obtained in the last step and water in a second settling tank according to the volume ratio of 1:6, controlling the salinity of the sludge liquid to be 12-15% and the pH value to be 8.5-9.5, and adding polymethacrylamidopropyl trimethyl ammonium chloride accounting for 0.01% of the mass of the sludge.
(4) Secondary sedimentation: and (4) settling the slurry mixed and rinsed in the step (3) in a second settling tank for 30min, returning the supernatant to the mining area to collect brine after the settling is finished, and feeding the sludge into the step (5).
(5) Primary filtration: and (4) carrying out horizontal spiral filtration and separation on the sludge obtained in the step (4), obtaining a filter cake, entering the next step, and returning the filtrate and the supernatant obtained in the step (4) to the mining area for brine mining.
(6) Primary washing: transferring the salt mud filter cake obtained in the step (5) into a first washing tank, simultaneously adding water with the salt mud volume ratio of 1:5, introducing flue gas into the bottom of the washing tank, maintaining for 15min, and controlling the flow rate of the flue gas to be 60m3/min。
(7) Secondary filtration: and (4) carrying out horizontal spiral filtration and separation on the sludge obtained in the step (6), obtaining a filter cake, entering the next step, and transferring the filtrate into the second settling tank in the step (2) for recycling.
(8) And (3) secondary washing: transferring the salt mud filter cake obtained in the step (5) into a second washing tank, simultaneously adding water with the salt mud volume ratio of 1:2, introducing flue gas into the bottom of the washing tank, maintaining for 10min, and controlling the flow rate of the flue gas to be 20m3/min。
(9) And (3) filtering for three times: and (3) carrying out horizontal spiral filtration and separation on the sludge obtained in the step (8) to obtain washed salt mud, and transferring the filtrate into the second settling tank in the step (2) for recycling.
Comparative example 1
According to the washing process of the lime flue gas method salt mud, the air floatation separation in the step (1) is changed into mechanical stirring separation, and the lime flue gas method salt mud is washed by the following steps:
(1) stirring and separating: adjusting the solid-liquid ratio of the raw material salt slurry to 1:3, starting mechanical stirring, and maintaining for 30 min.
(2) Primary sedimentation: and (4) settling the slurry subjected to air floatation separation in a settling tank I for 30min, returning the supernatant to the mining area for brine extraction after the settling is finished, and allowing the sludge to enter the step (3).
(3) Mixing and rinsing: and (3) performing convective mixed rinsing on the sludge obtained in the last step and water in a second settling tank according to the volume ratio of 1:4, controlling the salinity of the sludge liquid to be 12-15% and the pH value to be 8.5-9.5, and adding poly-hydroxypropyl dimethyl ammonium chloride accounting for 0.01% of the mass of the sludge.
(4) Secondary sedimentation: and (4) settling the slurry mixed and rinsed in the step (3) in a second settling tank for 30min, returning the supernatant to the mining area to collect brine after the settling is finished, and feeding the sludge into the step (5).
(5) Primary filtration: and (4) carrying out plate-and-frame filter pressing separation on the sludge obtained in the step (4), obtaining a filter cake, entering the next step, and returning the filtrate and the supernatant obtained in the step (4) to the mining area for brine mining.
(6) Primary washing: transferring the salt mud filter cake obtained in the step (5) into a first washing tank, simultaneously adding water with the salt mud volume ratio of 1:4, introducing flue gas into the bottom of the washing tank, maintaining for 10min, and controlling the flow rate of the flue gas to be 50m3/min。
(7) Secondary filtration: and (4) carrying out plate-and-frame filter pressing separation on the sludge obtained in the step (6), obtaining a filter cake, entering the next step, and transferring the filtrate into the second settling tank in the step (2) for recycling.
(8) And (3) secondary washing: transferring the salt mud filter cake obtained in the step (5) into a second washing tank, simultaneously adding water with the salt mud volume ratio of 1:2, introducing flue gas into the bottom of the washing tank, maintaining for 10min, and controlling the flow rate of the flue gas to be 20m3/min。
(9) And (3) filtering for three times: and (3) carrying out plate-and-frame filter pressing separation on the sludge obtained in the step (8) to obtain washed salt mud, and transferring the filtrate into the second settling tank in the step (2) for recycling.
Comparative example 2
According to the washing process of lime flue gas method salt mud, flue gas stirring in the steps (6) and (8) is changed into mechanical stirring, and the lime flue gas method salt mud is washed by the following steps:
(1) air flotation separation: adjusting the solid-liquid ratio of raw material salt mud slurry to 1:4, introducing flue gas into the bottom of the first settling tank, maintaining for 25min, and controlling the flow rate of flue gas to be 100m3/min。
(2) Primary sedimentation: and (4) settling the slurry subjected to air floatation separation in a settling tank I for 40min, returning the supernatant to the mining area after the settling is finished, and collecting brine, wherein the sludge enters the step (3).
(3) Mixing and rinsing: and (3) performing shear type mixing rinsing on the sludge obtained in the last step and water in a second settling tank according to the volume ratio of 1:8, controlling the salinity of the sludge liquid to be 12-15% and the pH value to be 8.5-9.5, and adding poly (dihydroxy propyl dimethyl ammonium chloride) accounting for 0.02% of the mass of the sludge.
(4) Secondary sedimentation: and (4) settling the slurry mixed and rinsed in the step (3) in a second settling tank for 40min, returning the supernatant to the mining area for brine mining after the settling is finished, and feeding the sludge into the step (5).
(5) Primary filtration: and (4) carrying out vacuum drum filtration separation on the sludge obtained in the step (4), obtaining a filter cake, entering the next step, and returning the filtrate and the supernatant obtained in the step (4) to the mining area for halogen mining.
(6) Primary washing: and (4) transferring the salt mud filter cake obtained in the step (5) into a first washing tank, simultaneously adding water with the salt mud volume ratio of 1:5, starting mechanical stirring, and maintaining for 15 min.
(7) Secondary filtration: and (4) carrying out vacuum drum filtration separation on the sludge obtained in the step (6), obtaining a filter cake, entering the next step, and transferring the filtrate into the second settling tank in the step (2) for recycling.
(8) And (3) secondary washing: and (4) transferring the salt mud filter cake obtained in the step (5) into a second washing tank, simultaneously adding water with the salt mud volume ratio of 1:1, starting mechanical stirring, and maintaining for 10 min.
(9) And (3) filtering for three times: and (3) carrying out vacuum drum filtration separation on the sludge obtained in the step (8) to obtain washed salt mud, and transferring the filtrate into the second settling tank in the step (2) for recycling.
Comparative example 3
According to the washing process of the lime flue gas method salt mud, no builder is added in the step (3), and the lime flue gas method salt mud is washed by the following steps:
(1) air flotation separation: adjusting the solid-liquid ratio of raw material salt mud slurry to 1:3, introducing flue gas into the bottom of the first settling tank, maintaining for 20min, and controlling the flow rate of flue gas to be 100m3/min。
(2) Primary sedimentation: and (4) settling the slurry subjected to air floatation separation in a first settling tank for 35min, returning the supernatant to the mining area for brine extraction after the settling is finished, and performing the step (3) on the sludge.
(3) Mixing and rinsing: and (3) carrying out convective mixed rinsing on the sludge obtained in the last step and water in a second settling tank according to the volume ratio of 1: 6.
(4) Secondary sedimentation: and (4) settling the slurry mixed and rinsed in the step (3) in a second settling tank for 30min, returning the supernatant to the mining area to collect brine after the settling is finished, and feeding the sludge into the step (5).
(5) Primary filtration: and (4) carrying out horizontal spiral filtration and separation on the sludge obtained in the step (4), obtaining a filter cake, entering the next step, and returning the filtrate and the supernatant obtained in the step (4) to the mining area for brine mining.
(6) Primary washing: transferring the salt mud filter cake obtained in the step (5) into a first washing tank, simultaneously adding water with the salt mud volume ratio of 1:5, introducing flue gas into the bottom of the first washing tank, maintaining for 15min, and controlling the flow rate of the flue gas to be 60m3/min。
(7) Secondary filtration: and (4) carrying out horizontal spiral filtration and separation on the sludge obtained in the step (6), obtaining a filter cake, entering the next step, and transferring the filtrate into the second settling tank in the step (2) for recycling.
(8) And (3) secondary washing: transferring the salt mud filter cake obtained in the step (5) into a second washing tank, simultaneously adding water with the salt mud volume ratio of 1:2, introducing flue gas into the bottom of the second washing tank, maintaining for 10min, and controlling the flow rate of the flue gas to be 20m3/min。
(9) And (3) filtering for three times: and (3) carrying out horizontal spiral filtration and separation on the sludge obtained in the step (8) to obtain washed salt mud, and transferring the filtrate into the second settling tank in the step (2) for recycling.
The salt slurry obtained in examples 1 to 3 and comparative examples 1 to 3 was subjected to performance tests, and the specific test results are shown in tables 1 to 3.
Table 1 is a numerical table of the water content of examples 1 to 3 and comparative examples 1 to 3 of the washing process of lime flue gas method salty mud according to the embodiment of the present invention.
The determination method comprises the following steps: loss on drying method (moisture content determination)
Weighing 10g of uniform sample crushed to below 2mm, weighing to 0.001g, placing the sample in a low-type weighing bottle which is dried and weighed at a specified temperature, obliquely opening a weighing bottle cap, placing the bottle cap into a constant-temperature drying box, gradually heating to 105 ℃, continuously drying for 2h, covering the bottle cap, taking out, transferring the bottle cap into a dryer, cooling to room temperature, weighing, drying for 1h each time, and weighing until the difference between two successive weighing is not more than 0.0005 g.
The moisture content in the sample is represented by mass fraction ω, and the value is represented by percentage (%), calculated according to formula (1):
in the formula:
m 1-sample before drying plus the weight of the weighing bottle in grams (g)
m 2-sample after drying plus the weight of the weighing bottle in grams (g)
m-weight the sample in grams (g)
The specific test results are shown in table 1:
TABLE 1 Performance test Table
| Water content (%) | |
| Example 1 | 17.2 |
| Example 2 | 16.9 |
| Example 3 | 17.5 |
| Comparative example 1 | 19.6 |
| Comparative example 2 | 21.4 |
| Comparative example 3 | 19.0 |
Table 2 is a table of values of magnesium and iron contents of the washed salt sludge of examples 1 to 3 and comparative examples 1 to 3 of the lime flue gas method salt sludge washing process according to the embodiment of the present invention.
The determination method comprises the following steps: ICP optical spectrum method (magnesium, iron content determination)
5.0g of salt slurry is weighed to be accurate to 0.0001g, 0.5mL of superior pure nitric acid is added, and the salt slurry is dissolved in a plastic volumetric flask with the constant volume of 50 mL. Measuring a standard solution with a certain volume of the component to be measured, moving the standard solution into a 100mL volumetric flask, and measuring the contents of magnesium and iron ions by adopting an ICP spectrometer.
Tolerance of relative error and results, the content of element (mg/kg) was measured according to the following formula
In formula (2):
W(ELement)-measuring the content of the element in units: mg/kg;
m2-mass of test sample, unit: g;
β(ELement)-the concentration of the elements in the sample after calibration, expressed in mg/L in the sample solution.
The absolute difference between two independent measurements obtained under repetitive conditions must not exceed 10% of the arithmetic mean. The specific results are shown in table 2:
TABLE 2 Performance test Table
| Magnesium (Mg) Mg/g | Iron (Fe) mg/kg | |
| Example 1 | 2.46 | 28.6 |
| Example 2 | 3.12 | 27.2 |
| Example 3 | 2.88 | 29.4 |
| Comparative example 1 | 5.24 | 36.2 |
| Comparative example 2 | 6.72 | 38.1 |
| Comparative example 3 | 3.50 | 28.2 |
Table 3 is a table of values of Chemical Oxygen Demand (COD) of the salt sludge washed in examples 1 to 3 and comparative examples 1 to 3 of the lime flue gas method salt sludge washing process according to the example of the present invention.
The determination method comprises the following steps: rapid digestion spectrophotometry (COD content determination)
1.0g of salt slurry is weighed to be accurate to 0.0001g, 0.5mL of high-grade pure sulfuric acid is added, and the salt slurry is dissolved in a plastic volumetric flask with the constant volume of 500 mL. The COD content in the salt mud is measured by adopting a 6B-3000A intelligent multi-parameter water quality tester, and the specific result is shown in Table 3:
TABLE 3 Performance test Table
| Chemical Oxygen Demand (COD) mg/kg | |
| Example 1 | 139 |
| Example 2 | 146 |
| Example 3 | 121 |
| Comparative example 1 | 452 |
| Comparative example 2 | 243 |
| Comparative example 3 | 195 |
Therefore, according to the washing process of the lime flue gas method salt mud provided by the embodiment of the invention, the salt mud obtained by washing the salt mud through the process provided by the invention has lower water content, impurity content and COD value obviously.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (15)
1. The process for washing the salt mud by the lime flue gas method is characterized by adopting an air floating type secondary sedimentation secondary washing process, which comprises the following steps:
s1, air flotation separation: adjusting the solid-liquid ratio of the raw material salt slurry to 1: 3-1: 4, and introducing flue gas into the bottom of the first settling tank;
s2, primary sedimentation: settling the slurry subjected to air floatation separation in a first settling tank, returning supernatant to an ore region for bittern collection after settling is finished, and allowing sludge to enter the next operation;
s3, mixed rinsing: mixing and rinsing the sludge obtained in the step S2 and water in a second settling tank according to the volume ratio of 1: 4-1: 8, and adding a builder;
s4, secondary sedimentation: settling the slurry subjected to the mixed rinsing in the step S3 in a second settling tank, returning supernatant to an ore region for bittern collection after settling is finished, and allowing sludge to enter the next operation;
s5, primary filtration: filtering and separating the sludge obtained in the step S4 to obtain a salt mud filter cake, and returning the filtrate and the supernatant obtained in the step S4 to the mining area for brine mining;
s6, primary washing: transferring the salt mud filter cake obtained in the step S5 into a first washing tank, adding water with the salt mud volume ratio of 1: 4-1: 5, and introducing flue gas into the bottom of the first washing tank;
s7, secondary filtration: filtering and separating the sludge obtained in the step S6 to obtain a salt mud filter cake, and transferring the filtrate into a second settling tank in the step S3 for recycling;
s8, secondary washing: transferring the salt mud filter cake obtained in the step S5 into a second washing tank, adding water with the salt mud volume ratio of 1: 1-1: 2, and introducing flue gas into the bottom of the washing tank;
s9, filtering for three times: and (5) filtering and separating the sludge obtained in the step S8 to obtain washed salt sludge, and transferring the filtrate to the second settling tank in the step S3 for recycling.
2. The process for washing salty mud according to claim 1, wherein the flue gas is introduced in step S1 for a period of 20-30 min.
3. The process for washing salty mud produced by lime flue gas method according to claim 2, wherein the flow rate of flue gas in step S1 is controlled to 80m3/min～100m3/min。
4. The process for washing salty mud according to claim 1, characterized in that the settling time in step S2 is 30-40 min.
5. The process for washing lime flue gas salt sludge as claimed in claim 1, wherein the builder in step S3 is any one of poly (hydroxypropyl) dimethyl ammonium chloride, poly (diallyl) dimethyl ammonium chloride, poly (methyl alkyl) diallyl ammonium chloride, poly (benzyl) diallyl ammonium chloride, poly (dihydroxypropyl) dimethyl ammonium chloride, poly (methacryloyloxyethyl) trimethyl ammonium chloride, and poly (methacrylamidopropyl) trimethyl ammonium chloride.
6. The process for washing lime flue gas method salty mud according to claim 1, wherein the manner of the mixed rinsing in the second settling tank in step S3 is any one of convection mixed rinsing, shear mixed rinsing and centrifugal mixed rinsing.
7. The process for washing salty mud according to the lime flue gas method of claim 1, wherein the salinity of the mud liquid is controlled to be 12-15% in the mixed rinsing in step S3.
8. The process for washing the salty mud produced by the lime flue gas method according to claim 7, wherein the pH value is controlled to be 8.5 to 9.5 in the mixed rinsing in step S3.
9. The process for washing salty mud according to the lime flue gas method of claim 8, wherein the builder is added in step S3 in an amount of 0.01-0.02% by mass of the mud residue.
10. The process for washing salty mud according to claim 1, characterized by settling for 30-40 min in step S4.
11. The process for washing salty mud produced by lime flue gas method according to claim 1, wherein the maintaining time in step S6 is 10min to 15min, and the flow rate of flue gas is controlled to be 50m to 60m3/min。
12. The process for washing salty mud produced by lime flue gas method according to claim 1, wherein the maintaining time in step S8 is 8min to 10min, and the flow rate of flue gas is controlled to be 20m to 30m3/min。
13. The process for washing lime flue gas process salty mud according to claim 1, wherein the filtrate from steps S7 and S9 is recycled to the system for use as a mixture of the ingredients of step S3, and the flue gas temperature is above 150 ℃.
14. The process for washing salty mud according to the lime flue gas method of claim 1, wherein the filtering manner in the step S5, the step S7 and the step S9 is any one of vacuum drum filtration, plate and frame filter pressing and horizontal spiral filtration.
15. The process for washing lime flue gas process salty mud according to claim 1, wherein step S1, step S6 and step S8 employ air-floating agitation.
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