A system for synergistically utilizing high-salinity wastewater and high-salinity solid waste in a steel enterprise

Abstract

The application provides a kind of steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system, which first filters out non-magnetic dust from sintering machine head dust through a pretreatment module, then performs multi-stage water washing and pressure filtration on the slurry obtained by mixing non-magnetic dust, blast furnace gas condensate water and concentrated salt water from a desalting station through a multi-stage water washing and pressure filtration module, to obtain multi-stage washing ash and multi-stage washing ash salt water, and finally obtains industrial grade NaCl, industrial grade KCl and crystallization mother liquor by purifying and separating the multi-stage washing ash salt water through a purification and separation module; the application uses non-magnetic dust, blast furnace gas condensate water and concentrated salt water from a desalting station as raw materials through a series of collaborative disposal technologies, solves the problem of alkali metal and chloride ion enrichment in the sintering machine system, and extracts industrial grade NaCl and industrial grade KCl from blast furnace gas condensate water and concentrated salt water from a desalting station, thereby improving resource utilization and increasing the benefits of steel enterprises.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coking wastewater treatment, and particularly relates to a steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system. BACKGROUND

[0002] The steel enterprise is a high energy consumption and high pollution enterprise, and a large amount of high-salinity wastewater and high-salinity solid waste are generated. The high-salinity wastewater such as blast furnace gas condensate water and desalination station concentrated salt water is mainly consumed by blast furnace slag flushing, but the normal operation of the blast furnace slag flushing equipment and the water slag quality are affected due to the high concentration of chloride ions in the high-salinity wastewater, and the high-salinity wastewater is difficult to dispose.

[0003] The high-salinity solid waste such as sintering machine head ash is mainly directly returned to the mine for recycling, but a large amount of alkali metal and chloride ions are contained in the machine head ash, and after the direct return to the mine for recycling, the alkali metal and chloride ions are enriched in the sintering machine, the sintering machine is "pasted with grate bars", the sintering ore yield and quality are reduced, and the low-quality sintering ore entering the blast furnace system will cause the blast furnace to be eroded, and seriously affect the service life of the blast furnace.

[0004] Therefore, a steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system is needed to solve the effective disposal problem of the high-salinity wastewater and high-salinity solid waste of the steel enterprise. SUMMARY

[0005] Therefore, the present application provides a steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system to solve the technical problem that the large amount of high-salinity wastewater and high-salinity solid waste generated by the existing steel enterprise cannot be effectively disposed.

[0006] The present application aims to achieve the following technical solutions:

[0007] In order to achieve the above technical purpose, the present application adopts the following technical solutions:

[0008] The present application provides a steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system, which comprises a pretreatment module, a multi-stage water washing pressure filtration module and a purification separation module connected in sequence.

[0009] The pretreatment module is used for screening non-magnetic dust removal ash in the sintering machine head dust removal ash; the multi-stage water washing pressure filtration module is used for multi-stage water washing pressure filtration treatment of the slurry after mixing of the non-magnetic dust removal ash, the blast furnace gas condensate water and the desalination station concentrated salt water, to obtain multi-stage water washing ash and multi-stage washing ash salt water, and the multi-stage water washing ash is returned to the sintering machine; and the purification separation module is used for purification separation treatment of the multi-stage washing ash salt water, to obtain industrial grade NaCl, industrial grade KCl and crystallization mother liquor.

[0010] Preferably, the sintering machine head dust includes No. 1 electric field dust, No. 2 electric field dust, No. 3 electric field dust and No. 4 electric field dust, and the pretreatment module is used for obtaining magnetic particle ore and first dust after magnetic separation treatment of the No. 1 electric field dust.

[0011] Preferably, the non-magnetic dust includes the first dust, the No. 2 electric field dust, the No. 3 electric field dust and the No. 4 electric field dust.

[0012] Preferably, the pretreatment module is a dry magnetic separation device, and the magnetic field strength is 500-3000Gs.

[0013] Preferably, the multi-stage water washing and filter pressing module includes a first alkaline water washing unit, a first filter pressing unit, a second water washing unit, a second filter pressing unit, a third water washing unit and a third filter pressing unit connected in sequence.

[0014] Preferably, the first alkaline water washing unit is used for obtaining a first mixed slurry after first alkaline water washing treatment of the first dust, blast furnace gas condensate water and desalted water station concentrated salt water mixed slurry; the first filter pressing unit is used for first filter pressing treatment of the first mixed slurry, and solid-liquid separation to obtain first washing dust and first washing dust salt water, and the first washing dust is returned to the sintering machine; the second water washing unit is used for obtaining a second mixed slurry after second water washing treatment of the No. 2 electric field dust and the first washing dust salt water mixed slurry; the second filter pressing unit is used for second filter pressing treatment of the second mixed slurry, and solid-liquid separation to obtain second washing dust and second washing dust salt water, and the second washing dust is returned to the sintering machine; the third water washing unit is used for obtaining a third mixed slurry after third water washing treatment of the No. 3 electric field dust, the No. 4 electric field dust and the second washing dust salt water mixed slurry; and the third filter pressing unit is used for third filter pressing treatment of the third mixed slurry, and solid-liquid separation to obtain third washing dust and third washing dust salt water, and the third washing dust is returned to the sintering machine.

[0015] Preferably, the water-dust ratio in the first alkaline water washing unit is (1-3):1, the reaction pH value is 7-9, and the reaction time is 0.5-1.5h; the reaction time in the second water washing unit is 0.5-1.5h; and the reaction time in the third water washing unit is 0.5-1.5h.

[0016] Preferably, the purification and separation module includes a multi-effect purification treatment submodule connected with the third filter pressing unit and a salt separation and crystallization submodule connected with the multi-effect purification treatment submodule.

[0017] Preferably, the multi-effect purification treatment submodule is used for obtaining crystallization mother liquor, multi-stage precipitation sludge and condensate water after multi-effect purification treatment of the third washing dust salt water; and the salt separation and crystallization submodule is used for obtaining industrial grade NaCl, industrial grade KCl and crystallization mother liquor after separation and crystallization treatment of the crystallization mother liquor.

[0018] Preferably, the multi-effect purification submodule includes an ultrasonic electrocatalytic oxidation unit, a primary desulfurization, magnesium removal and fluorine removal unit, a secondary desulfurization, calcium removal and heavy metal removal unit, and a triple-effect countercurrent evaporation unit connected in sequence.

[0019] The ultrasonic electrocatalytic oxidation unit is used to ultrasonically oxidize the tertiary washing brine to obtain ultrasonically oxidized brine; the primary desulfurization, magnesium removal, and fluoride removal unit is used to remove SO4 from the ultrasonically oxidized brine. 2- A coarse removal is performed, while simultaneously ultrasonic oxidation of Mg in the brine. 2+ and F - After removal, primary purified brine and primary precipitated sludge are obtained. The reagents added to the primary desulfurization, magnesium removal, and fluoride removal unit are Ca(OH)2, PAC, and PAM. The secondary desulfurization, calcium removal, and heavy metal removal unit is used to remove SO4 from the primary purified brine. 2- A secondary fine removal process is performed, while simultaneously removing Ca from the primary impurity-removing brine. 2+ After removing heavy metal ions, secondary impurity-removed brine and secondary precipitated sludge are obtained. The reagents added to the secondary desulfurization, calcium removal and heavy metal removal units are Na2CO3, Na2S, BaCl2, PAC and PAM. The triple-effect countercurrent evaporation unit is used to perform countercurrent step-by-step heating evaporation treatment on the secondary impurity-removed brine to obtain crystallization mother liquor and condensate.

[0020] Preferably, in the ultrasonic electrocatalytic oxidation unit: the frequency of the ultrasonic device is 50~500kHz, the catalyst is TiO2, the catalyst dosage is 100~300mg / L, and the pH value is 6~7; the reaction time in the reaction zone of the primary desulfurization, magnesium removal and fluorine removal unit is 0.4~0.6h; the reaction time in the reaction zone of the secondary desulfurization, calcium removal and heavy metal removal unit is 0.3~0.7h; and the temperature of the triple-effect countercurrent evaporation unit is 70~100℃.

[0021] Preferably, the salt separation and crystallization sub-module includes a sodium salt centrifugal separation unit, a freeze crystallization unit, and a potassium salt centrifugal separation unit connected in sequence;

[0022] The sodium salt centrifugal separation unit is used to centrifuge the crystallization mother liquor to obtain industrial-grade NaCl and centrifugal mother liquor; the freeze crystallization unit is used to freeze crystallize the centrifugal mother liquor to obtain potassium salt mixture; the potassium salt centrifugal separation unit is used to centrifuge the potassium salt mixture to obtain industrial-grade KCl and crystallization mother liquor, and the crystallization mother liquor is transported to the triple-effect countercurrent evaporation unit for reuse.

[0023] Preferably, the temperature of the freeze crystallization unit is 0~50℃.

[0024] Beneficial effects: the application provides a steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system, which first screens non-magnetic dusting ash in sintering machine head dust through a pretreatment module, then performs multistage water washing and filter pressing treatment on slurry obtained by mixing the non-magnetic dusting ash, blast furnace gas condensate water and concentrated salt water in a desalination station to obtain multistage water washing ash and multistage washing ash salt water, and finally performs purification and separation treatment on the multistage washing ash salt water to obtain industrial grade NaCl, industrial grade KCl and crystallization mother liquor; the non-magnetic dusting ash screened by the pretreatment module, the blast furnace gas condensate water and the concentrated salt water in the desalination station are used as raw materials to perform a series of collaborative treatment technologies, on one hand, the multistage water washing ash after the multistage water washing and filter pressing treatment is returned to the sintering machine for utilization, solving the problem of alkali metal and chloride ion enrichment in the sintering machine system, on the other hand, the multistage washing ash salt water extracted from the blast furnace gas condensate water and the concentrated salt water in the desalination station is purified and separated to obtain industrial grade NaCl and industrial grade KCl, thereby improving the resource utilization rate and increasing the benefit of the steel enterprise. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A structural framework diagram of the steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system provided for the embodiment of the application is provided.

[0026] Figure 2 A process flow diagram of the steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system provided for the embodiment 1 of the application is provided. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the application clearer, the application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0028] The application is aimed at the problem that a large amount of high-salinity wastewater and high-salinity solid waste generated by existing steel enterprises cannot be effectively disposed.

[0029] The application uses blast furnace gas condensate water, concentrated salt water in a desalination station and sintering machine head ash as raw materials to perform a series of collaborative treatment technologies, on one hand, the water washing ash from which alkali metal and chloride ions are removed is returned to the sintering machine for utilization, solving the problem of alkali metal and chloride ion enrichment in the sintering machine system, on the other hand, the salt components extracted from the above high-salinity wastewater and high-salinity solid waste are prepared into potassium chloride and sodium chloride products for sale, improving the resource utilization rate and increasing the benefit of the steel enterprise.

[0030] The present application solves the environmental protection pain points and difficulties of high-salt wastewater and high-salt solid waste in steel enterprises, and has great significance for protecting the ecological environment and the high-quality sustainable development of production enterprises.

[0031] Please refer to Figure 1 , Figure 1 The structural framework diagram of the steel enterprise high-salt wastewater and high-salt solid waste collaborative resource utilization system provided by the present application is provided; wherein the steel enterprise high-salt wastewater and high-salt solid waste collaborative resource utilization system provided by the present application comprises a pretreatment module, a multi-stage water washing pressure filtration module and a purification separation module connected in sequence;

[0032] The pretreatment module is used for screening non-magnetic dust removal ash in the sintering machine head dust removal ash; the multi-stage water washing pressure filtration module is used for multi-stage water washing pressure filtration treatment of the slurry mixed by the non-magnetic dust removal ash, the blast furnace gas condensate water and the desalted water station concentrated salt water to obtain multi-stage water washing ash and multi-stage washing ash salt water, and the multi-stage water washing ash is returned to the sintering machine; the purification separation module is used for purification separation treatment of the multi-stage washing ash salt water to obtain industrial grade NaCl, industrial grade KCl and crystallization mother liquor.

[0033] In the present application, the sintering machine head dust removal refers to the dust removal process of the waste gas discharged from the head of the sintering machine in the sintering process of steel production. The sintering machine head dust removal usually adopts various dust removal equipment and technology, such as electric dust collector, bag dust collector, electric bag composite dust collector, etc., through physical or chemical method to separate the dust in the waste gas, so that the purified waste gas can meet the environmental protection emission standard after being discharged, and the collected dust can be further treated or recycled.

[0034] Specifically, the sintering machine head ash is generally provided with 4-stage electric field for dust removal, wherein the iron content of the sintering machine head ash gradually decreases with the increase of the electric field level, and the salt content gradually increases.

[0035] Preferably, the sintering machine head dust removal ash comprises No. 1 electric field dust removal ash, No. 2 electric field dust removal ash, No. 3 electric field dust removal ash and No. 4 electric field dust removal ash, and the pretreatment module is used for magnetic separation treatment of the No. 1 electric field dust removal ash to obtain magnetic particle ore and first dust removal ash.

[0036] The non-magnetic dust removal ash comprises the first dust removal ash, the No. 2 electric field dust removal ash, the No. 3 electric field dust removal ash and the No. 4 electric field dust removal ash.

[0037] Preferably, the pretreatment module is a dry magnetic separation device, and the magnetic field strength is 500-3000Gs; the magnetic field strength in this range can adapt to the magnetic separation needs of different kinds of materials. For materials with weak magnetism, effective separation can be carried out under lower magnetic field strength; and for materials with strong magnetism, higher magnetic field strength can ensure more thorough separation effect.

[0038] In the embodiment of the present application, the multi-stage water washing pressure filtration module comprises a first alkaline water washing unit, a first pressure filtration unit, a second water washing unit, a second pressure filtration unit, a third water washing unit and a third pressure filtration unit connected in sequence.

[0039] The first alkaline water washing unit is used for performing first alkaline water washing treatment on the first slurry mixed by the first dedusting ash, the blast furnace gas condensate water and the concentrated salt water of the desalination water station to obtain the first mixed slurry.

[0040] Specifically, a large amount of water vapor is contained in the blast furnace gas generated during the blast furnace ironmaking. During the gas purification and conveying process, as the temperature of the gas gradually decreases, the water vapor will condense to form liquid water, i.e., the blast furnace gas condensate water. The main components of the blast furnace gas condensate water include acidic substances, suspended solids and heavy metals.

[0041] Specifically, the desalination water station usually adopts reverse osmosis, ion exchange and other processes to remove impurities in water to produce desalination water meeting specific requirements. In this process, most of the salt and other impurities in the raw water are intercepted, thereby forming concentrated salt water.

[0042] Specifically, NaOH is added to adjust the alkalinity in the first alkaline water washing unit, and air stirring and mechanical stirring are used to perform first alkaline water washing reaction on the first slurry to complete the water-solubility of the salt, thereby obtaining the first mixed slurry. The main reaction equation is as follows:

[0043] 4Fe 2+ + O2+ 2H2O→ 4Fe 3+ + 4OH - ;

[0044] Fe 3+ + 3OH - → Fe(OH)3↓.

[0045] Further, the water-cement ratio in the first alkaline water washing unit is (1-3): 1, the reaction pH value is 7-9, and the reaction time is 0.5-1.5 h. A reasonable water-cement ratio range can ensure the cleaning effect while avoiding excessive water consumption, reducing the water load and cost of subsequent treatment. The pH value controlled at 7-9 is relatively mild, which can effectively remove impurities and avoid the adverse effects of excessive alkalinity on equipment and subsequent treatment, such as corrosion of equipment, increased treatment difficulty, etc. The reaction time of 0.5-1.5 h can ensure that the impurities in the ash have enough time to fully contact, dissolve and react with water.

[0046] In the embodiment of the present application, the first pressure filtration unit is used for performing first pressure filtration treatment on the first mixed slurry, and the solid-liquid separation obtains the first water washing ash and the first washing ash salt water, and the first water washing ash is returned to the sintering machine.

[0047] In the embodiment of the present application, the secondary water washing unit is used to perform secondary water washing treatment on the second slurry obtained by mixing the dust collected by the No. 2 electric field and the salt water after the first dust washing, so as to obtain a second mixed slurry; wherein the reaction time in the secondary water washing unit is 0.5-1.5 h.

[0048] In the embodiment of the present application, the secondary pressure filtration unit is used to perform secondary pressure filtration treatment on the second mixed slurry, so as to obtain secondary washed dust and secondary dust washing salt water after solid-liquid separation, and the secondary washed dust is returned to the sintering machine.

[0049] In the embodiment of the present application, the tertiary water washing unit is used to perform tertiary water washing treatment on the third slurry obtained by mixing the dust collected by the No. 3 electric field, the dust collected by the No. 4 electric field and the secondary dust washing salt water, so as to obtain a third mixed slurry; wherein the reaction time in the tertiary water washing unit is 0.5-1.5 h.

[0050] In the embodiment of the present application, the tertiary pressure filtration unit is used to perform tertiary pressure filtration treatment on the third mixed slurry, so as to obtain tertiary washed dust and tertiary dust washing salt water after solid-liquid separation, and the tertiary washed dust is returned to the sintering machine.

[0051] In the embodiment of the present application, the purification separation module comprises a multi-effect purification treatment sub-module connected with the tertiary pressure filtration unit and a salt separation and crystallization sub-module connected with the multi-effect purification treatment sub-module.

[0052] The multi-effect purification treatment sub-module is used to perform multi-effect purification treatment on the tertiary dust washing salt water, so as to obtain a crystallization mother liquor, multi-stage precipitation sludge and condensate water; and the salt separation and crystallization sub-module is used to perform separation and crystallization treatment on the crystallization mother liquor, so as to obtain industrial-grade NaCl, industrial-grade KCl and a crystallization mother liquor.

[0053] Specifically, the multi-effect purification treatment sub-module comprises an ultrasonic wave electro-catalytic oxidation unit, a first sulfur removal and magnesium and fluorine removal unit, a second sulfur removal and calcium and heavy metal removal unit and a three-effect countercurrent evaporation unit connected in sequence.

[0054] The ultrasonic wave electro-catalytic oxidation unit is used to perform ultrasonic oxidation treatment on the tertiary dust washing salt water, so as to obtain ultrasonic oxidation salt water.

[0055] Specifically, an ultrasonic wave generator, an electrochemical oxidation device and a catalyst are arranged in the ultrasonic wave catalytic oxidation unit, on the one hand, COD (Chemical Oxygen Demand) and NH4 + + are removed from the dust washing salt water, and on the other hand, cavitation and turbulent activation are performed on the tertiary dust washing salt water, and the treated ultrasonic oxidation salt water is sent to the first sulfur removal and magnesium and fluorine removal unit. The main reaction equation in the ultrasonic wave catalytic oxidation unit is as follows:

[0056] 2Cl - -2e -→ Cl2;

[0057] Cl2 + H2O → HCl + HClO;

[0058] 2NH4 + + 3HClO → N2↑ + 3H2O + 5H + + 3Cl - .

[0059] Preferably, in the ultrasonic electro-catalytic oxidation unit: the frequency of the ultrasonic device is 50-500 kHz, the catalyst is TiO2, the catalyst dosage is 100-300 mg / L, and the pH value is 6-7; wherein, the ultrasonic device can generate sufficient energy in this frequency range to cause cavitation effect in the solution. The cavitation effect can generate local high temperature, high pressure and strong shock wave, which helps to destroy the molecular structure of organic matter and promote the progress of oxidation reaction; under certain conditions, TiO2 can absorb light energy to generate electron-hole pairs, and these electrons and holes can react with dissolved oxygen, water molecules and the like in water to produce active species such as hydroxyl radicals with strong oxidizing property, thereby effectively oxidizing and decomposing organic matter; under the condition of neutral to weakly acidic pH value of 6-7, the catalytic activity of TiO2 is relatively high, at this time, the charge state of the catalyst surface and the generation efficiency of active species are relatively suitable, which is conducive to the progress of oxidation reaction.

[0060] In the embodiment of the application, the primary sulfur removal and magnesium and fluorine removal unit is used for performing primary rough removal on SO4 2- in the ultrasonic oxidation brine, and simultaneously removing Mg 2+ and F - in the ultrasonic oxidation brine to obtain primary impurity removal brine and primary precipitation sludge; the primary precipitation sludge is dewatered and then transported for disposal, and the reaction time of the reaction zone of the primary sulfur removal and magnesium and fluorine removal unit is 0.4-0.6 h; wherein, the reaction zone, coagulation zone and precipitation zone are arranged in the primary sulfur removal and magnesium and fluorine removal unit, Ca(OH)2, PAC (Polyaluminium Chloride, polyaluminum chloride) and PAM (Polyacrylamide, polyacrylamide) are added, primary rough removal is performed on SO4 2- , and removal is performed on Mg 2+ and F - , and the main reaction equations are as follows:

[0061] Ca 2+ + SO4 2- → CaSO4↓;

[0062] Ca 2+ + 2F - → CaF2↓;

[0063] Mg2+ + 2OH - → Mg(OH)2↓.

[0064] In the embodiment of the present application, the secondary sulfur removal and calcium and heavy metal removal unit is used to remove SO4 2- in the primary impurity removal brine again, and remove Ca 2+ and heavy metal ions in the primary impurity removal brine to obtain secondary impurity removal brine and secondary precipitation sludge; the secondary precipitation sludge is dewatered and then transported out for disposal, and the reaction time of the reaction zone of the secondary sulfur removal and calcium and heavy metal removal unit is 0.3-0.7h.

[0065] Specifically, the reaction zone, coagulation zone and precipitation zone are arranged in the secondary sulfur removal and calcium and heavy metal removal unit, Na2CO3, Na2S, BaCl2, PAC and PAM are added, SO4 2- is removed again, Ca 2+ and heavy metal ions (such as Cu 2+ , Pb 2+ , Zn 2+ ) are removed, and the main reaction equations are as follows:

[0066] Ba 2+ + SO4 2- → BaSO4↓;

[0067] Ca 2+ + CO3 2+ → CaCO3↓;

[0068] Cu 2+ + S 2- → CuS↓;

[0069] Pb 2+ + S 2- → PbS↓;

[0070] Zn 2+ + S 2- → ZnS↓.

[0071] In the embodiment of the present application, the three-effect countercurrent evaporation unit is used to perform countercurrent step-by-step warming evaporation treatment on the secondary impurity removal brine to obtain crystallization mother liquor and condensed water, and the temperature of the three-effect countercurrent evaporation unit is 70-100℃; in the three-effect countercurrent evaporation unit, the countercurrent step-by-step warming evaporation reaction is performed, NaCl is preferentially precipitated, the water vapor evaporated is condensed to form condensed water for reuse, and the crystallization mother liquor produced is sent to the sodium salt centrifugal separation unit.

[0072] In the embodiment of the present application, the salt separation and crystallization submodule comprises a sodium salt centrifugal separation unit, a freezing crystallization unit and a potassium salt centrifugal separation unit connected in sequence.

[0073] Specifically, the sodium salt centrifugal separation unit is used to obtain industrial-grade NaCl and a centrifugal mother liquor after centrifugal treatment of the crystallization mother liquor; in the sodium salt centrifugal separation unit, solid-liquid separation is completed by a centrifugal device to separate NaCl crystals, which are sent to the sodium salt drying unit for dehydration and drying to become industrial-grade NaCl products.

[0074] Specifically, the freezing crystallization unit is used to obtain a potassium salt mixed liquor after freezing crystallization treatment of the centrifugal mother liquor; the freezing crystallization unit precipitates KCl in the centrifugal mother liquor by cooling, and the potassium salt mixed liquor with precipitated KCl is sent to the potassium salt centrifugal separation unit; wherein the temperature of the freezing crystallization unit is 0-50℃.

[0075] Specifically, the potassium salt centrifugal separation unit separates KCl crystals by a centrifugal device to complete solid-liquid separation of the potassium salt mixed liquor, which are sent to the potassium salt drying subunit for dehydration and drying to become industrial-grade KCl products for sale; at the same time, the potassium salt centrifugal separation unit sends the obtained crystallization mother liquor to the three-effect countercurrent evaporation unit for internal reuse.

[0076] The technical solutions of the present application will be further described in combination with specific embodiments.

[0077] Embodiment 1:

[0078] Please refer to Figure 1 , the steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system provided by the present application comprises a pretreatment module, a multi-stage water washing filter pressing module and a purification separation module connected in sequence.

[0079] The pretreatment module is used to screen out non-magnetic dust from the dust at the head of the sintering machine; the multi-stage water washing filter pressing module is used to obtain multi-stage washing ash and multi-stage washing ash brine by multi-stage water washing filter pressing treatment of the slurry mixed by the non-magnetic dust, the blast furnace gas condensate water and the concentrated brine of the desalination water station, and return the multi-stage washing ash to the sintering machine; the purification separation module is used to obtain industrial-grade NaCl, industrial-grade KCl and crystallization mother liquor by purification separation treatment of the multi-stage washing ash brine.

[0080] Please refer to Figure 2 , Figure 2 The process flow chart of the steel enterprise high-salinity wastewater and high-salinity solid waste collaborative resource utilization system provided by Embodiment 1 of the present application; the specific process flow steps are as shown in Figure 2

[0081] ​(1) First, the sintering machine head 1# electric field of sintering plant dust is sent to the magnetic separation unit in the pretreatment module, the magnetic particles are separated and returned to the sintering machine for recycling, and the remaining first dust is mixed with the first slurry after the condensate water and desalted water station of blast furnace gas and the concentrated salt water is sent to the first alkaline water washing unit. In the first alkaline water washing unit, NaOH is added to adjust the alkali, and air stirring and mechanical stirring are used for reaction, and after the water-soluble salt is completed, the obtained first mixed slurry is sent to the first pressure filtration unit to complete the solid-liquid separation. The dewatered first water washing ash returns to the sintering machine, and the salted first washing ash salt water is sent to the second water washing unit. The main reaction equation is as follows:

[0082] 4Fe 2+ + O2+ 2H2O→ 4Fe 3+ + 4OH - ;

[0083] Fe 3+ + 3OH - → Fe(OH)3↓;

[0084] Specifically, the sintering machine head dust is generally provided with 4-stage electric field for dust removal, and the composition of the sintering machine 1#-4# electric field dust of a certain steel enterprise is shown in Table 1. It can be found from Table 1 that the compositions of the machine head dust of each stage electric field are significantly different, wherein the iron content gradually decreases with the increase of the stage number of the electric field, and the salt content gradually increases.

[0085] Table 1: Composition of sintering machine 1#-4# electric field dust of a typical steel enterprise

[0086]

[0087] Through the above analysis, the 1#-4# electric field dust is considered to be washed from the following three aspects:

[0088] Firstly, the Fe element in the sintering machine head dust mainly exists in the form of Fe2O3 and Fe3O4. The particle size of the dust of each stage electric field is analyzed, and it is found that the particle size of the 1# electric field dust is larger. If directly washed and pressure filtered, a large amount of sediment will be deposited in the water washing tank, thereby blocking the equipment. At the same time, due to the large difference in particle size and other dust, there is a problem of pressure filtration difficulty. Therefore, the 1# electric field dust is first separated by magnetic separation to preferentially separate the large particle Fe2O3 and Fe3O4 for direct return to the sintering machine to solve the above problems.

[0089] Secondly, the weight ratio of the 4-stage electric field dust is as follows:

[0090] 1st electric field dedusting ash: 2nd electric field dedusting ash: 3rd electric field dedusting ash: 4th electric field dedusting ash = 10:8:1:1. Because the water washing process needs a certain water-cement ratio, generally (1~4):1, compared with mixing the four electric field dedusting ashes and then washing, the water quantity can be reduced by about 50% in the quality-graded series water washing, which can greatly reduce the scale of the subsequent impurity removal process and the evaporation and salt separation process, thereby reducing the investment and operating cost.

[0091] Thirdly, compared with mixing the four electric field dedusting ashes and then washing, the quality-graded water washing can achieve a higher water washing concentration gradient in the order of gradually increasing salt content, which can greatly promote the water solubility of the salt and promote the separation of the salt in the sintering machine head dedusting ash to the multi-stage ash washing salt water, which can better solve the problem of alkali metal ion enrichment in the sintering machine and can recover valuable metals at a higher proportion.

[0092] Specifically, the water quality of the blast furnace gas condensate water of a certain steel enterprise is shown in Table 2:

[0093] Table 2: Water quality table of blast furnace gas condensate water of a certain steel enterprise

[0094]

[0095] According to the water quality, the blast furnace gas condensate water and the concentrated salt water of the salt removal station are used as the water source for water washing, mainly for the following three reasons:

[0096] Firstly, from the composition of the sintering machine head ash, the molar ratio of alkali metal ions to chloride ions is about 1.2:1, which is still a certain distance from 1:1, and a certain proportion of chloride ions needs to be supplemented. The blast furnace gas condensate water and the concentrated salt water of the salt removal station contain high-concentration chloride ions, which can solve the above problem.

[0097] Secondly, the target effective element in the sinter is Fe element, and the blast furnace gas condensate water contains high-concentration divalent iron ions and trivalent iron ions. Through air oxidation and alkaline precipitation, a large amount of iron hydroxide sludge is formed, which is separated by pressure filtration into the water washing ash and then returned to the sinter, thereby recycling the iron element in the wastewater and improving the grade of iron in the sinter.

[0098] Thirdly, the particle size of the sintering machine head ash is very small, belonging to sub-micron dust particles, and its surface has strong hydrophobicity, which is easy to cause agglomeration in the water washing unit, thereby reducing the dissolution effect of potassium and sodium salt. The concentrated salt water of the salt removal station contains a certain amount of surfactant, such as cetyltrimethylammonium bromide, etc. The surfactant can disperse the ash particles of the sintering machine head ash, increase the contact area between the ash particles and water, and promote the dissolution of the salt in the ash.

[0099] (2) Secondly, the second slurry mixed by the No. 2 electric field dust removal ash of the sintering machine head and the first-stage washing ash brine is sent to the second-stage water washing unit, fully stirred and reacted in the second-stage water washing unit, and after the water-solubility of the salt is completed, the obtained second mixed slurry is sent to the second-stage pressure filtration unit to complete the solid-liquid separation, and the dewatered second-stage washing ash is returned to the sintering machine, and the salt-dissolved second-stage washing ash brine is sent to the third-stage water washing unit.

[0100] (3) The third slurry mixed by the No. 3 electric field dust removal ash of the sintering machine head, the No. 4 electric field dust removal ash of the sintering machine head and the second-stage washing ash brine is sent to the third-stage water washing unit, fully stirred and reacted in the third-stage water washing unit, and after the water-solubility of the salt is completed, the obtained third mixed slurry is sent to the third-stage pressure filtration unit to complete the solid-liquid separation, and the dewatered third-stage washing ash is returned to the sintering machine, and the salt-dissolved third-stage washing ash brine is sent to the ultrasonic wave electro-catalytic oxidation unit.

[0101] (4) An ultrasonic wave generator, an electrochemical oxidation device and a catalyst are arranged in the ultrasonic wave catalytic oxidation unit, on the one hand, COD and NH4 + in the third-stage washing ash brine are removed, and on the other hand, cavitation and turbulent flow activation are performed on the third-stage washing ash brine, and the treated ultrasonic wave oxidation brine is sent to the first-stage sulfur removal and magnesium and fluorine removal unit. The main reaction equations in the ultrasonic wave catalytic oxidation unit are as follows:

[0102] 2Cl - -2e - →Cl2;

[0103] Cl2+H2O→HCl+HclO;

[0104] 2NH4 + +3HClO→N2↑+3H2O+5H + +3Cl - 。

[0105] Specifically, the ultrasonic wave electro-catalytic oxidation mainly considers the following three reasons:

[0106] Firstly, the third-stage washing ash brine has a large viscosity coefficient, which is not conducive to the reaction, while the ultrasonic wave has the effect of cavitation and turbulent flow activation on water, which can greatly promote the reaction rate of catalytic oxidation and the subsequent unit.

[0107] Secondly, the third-stage washing ash brine contains a certain amount of COD, in order to avoid its influence on the quality of the subsequent potassium and sodium salt, the COD must be removed in the front process, and if the Fenton process (a kind of advanced oxidation technology, mainly used for treating refractory organic wastewater) is used, a large amount of impurity ions will be introduced, which will bring greater burden to the subsequent treatment process, therefore, the electro-catalytic oxidation is adopted, that is, it has a higher organic matter removal rate in high-salt water, and also avoids the introduction of new impurity ions.

[0108] Thirdly, because of the adoption of blast furnace gas condensate water, if a certain amount of ammonia nitrogen is introduced, it needs to be removed. When the electro-catalytic oxidation process is used to treat wastewater containing a large amount of chloride ions, a large amount of hypochlorous acid will be produced, and the hypochlorous acid will react with ammonia nitrogen through the principle of "breakpoint chlorination" to oxidize the ammonia nitrogen into nitrogen gas and remove the ammonia nitrogen.

[0109] (5) In the first sulfur removal and magnesium removal and fluorine removal unit, a reaction zone, a coagulation zone and a sedimentation zone are arranged, Ca(OH)2, PAC and PAM are added, SO4 2- is removed in one time, Mg 2+ and F - are removed, and first impurity removal brine and first sedimentation sludge are obtained, and the main reaction equations are as follows:

[0110] Ca 2+ + SO4 2- → CaSO4↓;

[0111] Ca 2+ + 2F - → CaF2↓;

[0112] Mg 2+ + 2OH - → Mg(OH)2↓.

[0113] (6) The first impurity removal brine treated by the first sulfur removal and magnesium removal and fluorine removal unit is sent to the second sulfur removal and calcium removal and heavy metal removal unit, and the first sedimentation sludge is dewatered and then transported out for disposal. In the second sulfur removal and calcium removal and heavy metal removal unit, a reaction zone, a coagulation zone and a sedimentation zone are arranged, Na2CO3, Na2S, BaCl2, PAC and PAM are added, SO4 2- is removed in the second time, Ca 2+ and heavy metal ions (such as Cu 2+ , Pb 2+ , Zn 2+ ) are removed, and second impurity removal brine and second sedimentation sludge are obtained, and the main reaction equations are as follows:

[0114] Ba 2+ + SO4 2- → BaSO4↓;

[0115] Ca 2+ + CO3 2+ → CaCO3↓;

[0116] Cu 2+ + S 2- → CuS↓;

[0117] Pb 2+ + S 2- → PbS↓;

[0118] Zn 2+ +S 2- →ZnS↓.

[0119] (7) The secondary impurity removal brine treated by the secondary sulfur removal and calcium removal and heavy element removal unit is sent to the three-effect countercurrent evaporation unit. The secondary precipitation sludge generated is dewatered and then transported for disposal. In the three-effect countercurrent evaporation unit, a countercurrent step-by-step warming evaporation reaction is performed. NaCl is preferentially precipitated. The water vapor evaporated is condensed to form condensed water for reuse. The crystallization mother liquor generated is sent to the sodium salt centrifugal separation unit.

[0120] (8) In the sodium salt centrifugal separation unit, the crystallization mother liquor is subjected to solid-liquid separation by a centrifugal device to separate out NaCl crystals, which are sent to the sodium salt drying unit for dewatering and drying to become industrial-grade NaCl products for sale. The centrifugal mother liquor obtained after solid-liquid separation is sent to the refrigeration crystallization unit to precipitate KCl by cooling. The mixed liquid from which KCl is precipitated is sent to the potassium salt centrifugal separation unit, which is subjected to solid-liquid separation by a centrifugal device to separate out KCl crystals, which are sent to the potassium salt drying unit for dewatering and drying to become industrial-grade KCl products for sale. The crystallization mother liquor from the solid-liquid separation of the potassium salt centrifugal separation unit is sent to the three-effect countercurrent evaporation unit for reuse.

[0121] In summary, compared with the prior art, the application has the following advantages after adopting the technical scheme:

[0122] (1) High resource coupling degree: The two kinds of difficult-to-dispose waste of the steel enterprise are subjected to a series of coupling reactions by the method of the application, so that the high-salt wastewater and high-salt solid waste, which originally needed to be disposed of separately, are subjected to collaborative disposal. When the high-salt wastewater is disposed of separately to achieve zero discharge, a process flow of pretreatment + membrane treatment + evaporation treatment needs to be used, which requires a large amount of investment and operating costs. When the high-salt solid waste is treated separately by industrial water washing, on the one hand, a large amount of industrial fresh water needs to be consumed, and on the other hand, water washing + impurity removal + evaporation are also needed, and chloride ions also need to be supplemented to adjust the ratio of alkali metals: chloride ions to complete the recovery of alkali metals. Compared with the investment and operating costs of the above separate treatment, the collaborative resource utilization method of the application reduces the investment by 30% to 50% and the operating costs by 10% to 20%.

[0123] (2) Turning waste into treasure and reducing carbon emissions: The iron ions in the blast furnace gas condensate water are recovered into the sintering system, improving the iron grade of the sinter; the multi-grade water washing process is adopted to maximize the extraction of potassium salt and sodium salt in the sinter machine head ash into the ash washing brine, and then the impurity removal + evaporation salt separation method is adopted to produce potassium chloride and sodium chloride salt products, and the condensate water is reused, improving the resource utilization rate of the steel enterprise.

[0124] (3) The synergistic effect of environmental protection and economy is high: the high-salinity wastewater and high-salinity solid waste in the steel enterprise are coupled with the sintering main process line to form internal circulation, and high-value-added products are produced, thereby reducing the cost and increasing the benefit of the enterprise. The environmental protection pain points and difficulties of the wastewater and solid waste in the steel enterprise are solved, the ecological environment is protected, good economic benefits are generated, the operation cost is reduced, and the product value is improved. The high-quality sustainable development of the production enterprise has great significance.

[0125] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A system for the synergistic utilization of high-salinity wastewater and high-salinity solid waste from steel enterprises, characterized in that, It includes a pretreatment module, a multi-stage water washing and filter press module, and a purification and separation module connected in sequence; The pretreatment module is used to screen out non-magnetic dust from the dust collector at the sintering machine head; the multi-stage water washing and filtration module is used to perform multi-stage water washing and filtration on the slurry after mixing the non-magnetic dust, blast furnace gas condensate, and concentrated brine from the demineralization station to obtain multi-stage water-washed ash and multi-stage water-washed brine, and then return the multi-stage water-washed ash to the sintering machine; the purification and separation module is used to purify and separate the multi-stage water-washed brine to obtain industrial-grade NaCl, industrial-grade KCl, and crystallization mother liquor; The dust collected from the sintering machine head includes dust collected from electric fields 1, 2, 3, and 4. The pretreatment module is used to perform magnetic separation on the dust collected from electric field 1 to obtain magnetic particle ore and the first dust collected. The non-magnetic dust collected includes the first dust collected, the dust collected from electric fields 2, 3, and 4. The multi-stage water washing and filtration module includes a first-stage alkaline water washing unit, a first-stage filtration unit, a second-stage water washing unit, a third-stage water washing unit, and a third-stage filtration unit connected in sequence. The first-stage alkaline water washing unit is used to perform a first-stage alkaline water washing treatment on the first slurry obtained by mixing the first dust collector ash, the blast furnace gas condensate, and the concentrated brine from the demineralized water station to obtain a first mixed slurry. The first-stage filtration unit is used to perform a first-stage filtration treatment on the first mixed slurry, separating the solid and liquid to obtain first-stage washed ash and first-stage washed ash brine, and returning the first-stage washed ash to the sintering machine. The second-stage water washing unit is used to process the dust collector ash from the No. 2 electric field and the first-stage washed ash... The second slurry, after being mixed with ash and brine, undergoes a second-stage water washing treatment to obtain a second mixed slurry. The second-stage filter press unit is used to perform a second-stage filter press treatment on the second mixed slurry, and after solid-liquid separation, a second-stage washed ash and a second-stage washed ash brine are obtained. The second-stage washed ash is then returned to the sintering machine. The third-stage water washing unit is used to perform a third-stage water washing treatment on the third slurry, after being mixed with the dust from the No. 3 electric field, the dust from the No. 4 electric field, and the second-stage washed ash brine, to obtain a third mixed slurry. The third-stage filter press unit is used to perform a third-stage filter press treatment on the third mixed slurry, and after solid-liquid separation, a third-stage washed ash and a third-stage washed ash brine are obtained. The third-stage washed ash is then returned to the sintering machine.

2. The co-utilization system for high-salinity wastewater and high-salinity solid waste in steel enterprises according to claim 1, characterized in that, The pretreatment module is a dry magnetic separator with a magnetic field strength of 500~3000Gs.

3. The co-utilization system for high-salinity wastewater and high-salinity solid waste in steel enterprises according to claim 1, characterized in that, The water-cement ratio in the primary alkaline water washing unit is (1~3):1, the reaction pH is 7~9, and the reaction time is 0.5~1.5h; the reaction time in the secondary water washing unit is 0.5~1.5h; and the reaction time in the tertiary water washing unit is 0.5~1.5h.

4. The co-utilization system for high-salinity wastewater and high-salinity solid waste in steel enterprises according to claim 1, characterized in that, The purification and separation module includes a multi-effect purification sub-module connected to the three-stage filter press unit and a salt separation and crystallization sub-module connected to the multi-effect purification sub-module. The multi-effect purification submodule is used to perform multi-effect purification on the three-stage washing brine to obtain crystallization mother liquor, multi-stage precipitated sludge and condensate; the salt separation and crystallization submodule is used to separate and crystallize the crystallization mother liquor to obtain industrial-grade NaCl, industrial-grade KCl and crystallization mother liquor.

5. The co-utilization system for high-salinity wastewater and high-salinity solid waste in steel enterprises according to claim 4, characterized in that, The multi-effect purification sub-module includes an ultrasonic electrocatalytic oxidation unit, a primary desulfurization, magnesium removal and fluorine removal unit, a secondary desulfurization, calcium removal and heavy weight removal unit, and a triple-effect countercurrent evaporation unit connected in sequence. The ultrasonic electrocatalytic oxidation unit is used to ultrasonically oxidize the tertiary washing brine to obtain ultrasonically oxidized brine; the primary desulfurization, magnesium removal, and fluoride removal unit is used to remove SO4 from the ultrasonically oxidized brine. 2- A coarse removal is performed, simultaneously removing Mg from the ultrasonically oxidized brine. 2+ and F - After removal, primary desulfurization brine and primary precipitated sludge are obtained. The reagents added in the primary desulfurization, magnesium removal, and fluoride removal unit are Ca(OH)2, PAC, and PAM. The secondary desulfurization, calcium removal, and heavy metal removal unit is used to remove SO4 from the primary desulfurization brine. 2- A secondary fine removal process is performed, simultaneously removing Ca from the primary impurity-removing brine. 2+ After removing heavy metal ions, secondary impurity-removed brine and secondary precipitated sludge are obtained. The reagents added to the secondary desulfurization, calcium removal and heavy metal removal unit are Na2CO3, Na2S, BaCl2, PAC and PAM. The triple-effect countercurrent evaporation unit is used to perform countercurrent step-by-step heating evaporation treatment on the secondary impurity-removed brine to obtain the crystallization mother liquor and the condensate.

6. The co-utilization system for high-salinity wastewater and high-salinity solid waste in steel enterprises according to claim 5, characterized in that, In the ultrasonic electrocatalytic oxidation unit: the frequency of the ultrasonic device is 50~500kHz, the catalyst is TiO2, the catalyst dosage is 100~300mg / L, and the pH value is 6~7; the reaction time in the reaction zone of the primary desulfurization, magnesium removal, and fluorine removal unit is 0.4~0.6h; the reaction time in the reaction zone of the secondary desulfurization, calcium removal, and heavy metal removal unit is 0.3~0.7h; and the temperature of the triple-effect countercurrent evaporation unit is 70~100℃.

7. The co-utilization system for high-salinity wastewater and high-salinity solid waste in iron and steel enterprises according to claim 5, characterized in that, The salt separation and crystallization sub-module includes a sodium salt centrifugal separation unit, a freeze crystallization unit, and a potassium salt centrifugal separation unit connected in sequence. The sodium salt centrifugal separation unit is used to centrifuge the crystallization mother liquor to obtain the industrial-grade NaCl and the centrifugation mother liquor; the freeze crystallization unit is used to freeze crystallize the centrifugation mother liquor to obtain the potassium salt mixture; the potassium salt centrifugal separation unit is used to centrifuge the potassium salt mixture to obtain the industrial-grade KCl and the crystallization mother liquor, and the crystallization mother liquor is transported to the triple-effect countercurrent evaporation unit for reuse.

8. The co-utilization system for high-salinity wastewater and high-salinity solid waste in steel enterprises according to claim 7, characterized in that, The temperature of the freeze crystallization unit is 0~50℃.

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