Strong brine treatment process for iron and steel enterprises

Abstract

The invention provides a strong brine treatment process for iron and steel enterprises. The strong brine treatment process is characterized by comprising the following steps: 1) strong brine hardness removal and separation; 2) pretreating the separated strong brine; 3) ultrafiltration of the pretreated brine; 4) desalting the ultrafiltration water; 5) desalted water softening; 6) controlling chlorine in softened water; and 7) chlorine-controlled water absorption. The amount of the strong brine can be reduced to 55m < 3 > / h which is far lower than the strong brine absorption capacity 83m < 3 > / h of a blast furnace process, the absorption balance requirement of a whole-process iron and steel enterprise under the condition of an inferior V-type water source is completely met, meanwhile, the water quality of reuse water is greatly improved, the water quality of production water supply is improved by more than 30%, and zero emission of the strong brine is completely realized; after zero discharge of the strong brine is realized, the conductivity of production water supply is improved from 3700 [mu] s / cm to 900 [mu] s / cm and is improved by 32%, and a solid foundation is laid for stable operation of steel production equipment.

Description

Technical Field

[0001] The invention relates to a concentrated brine treatment process for a steel enterprise, belonging to the technical field of wastewater treatment. Background Art

[0002] Steel enterprises are large water users, especially the circulating cooling devices of key equipment require a large amount of soft water or desalted water. At present, the preparation of soft water and desalted water generally adopts the double membrane method, that is, ultrafiltration membrane + reverse osmosis membrane for treatment. The desalted water produced by this treatment process has a water production rate of about 70%, and the remaining 30% is high-salt water, which also contains various organic and inorganic pollutants. If it is discharged directly, it will inevitably cause pollution to the soil, surface water, and river basins. If it is discharged into the municipal sewage treatment system, it will be unfavorable for the formation of activated sludge due to excessive total dissolved solids. With the restrictions on high water consumption and industrial water discharge in the steel industry, the discharge and treatment of high-salt water has become a major problem currently facing the industry.

[0003] The water quality of production water used by most inland full-process steel enterprises is extremely poor. The raw water quality is mostly Class IV water, Class V water, or even Class V water. The concentrated brine produced under such water quality conditions is more than 5 times the salt content of full-process steel enterprises in the Yangtze River and Yellow River basins. However, the steel enterprises have limited ways to absorb the salt, and recycling will lead to salt accumulation in the entire reclaimed water circulation system, deterioration of water quality, and a vicious cycle. The output of high-salt water is large and the salt concentration is high. It is not realistic to desalinate and reuse all high-salt water. Therefore, the existing technology must be improved. Summary of the invention

[0004] In order to achieve zero discharge of high-salt water in the steel industry, the problem of excessive salt accumulation during the recycling and reuse of high-salt water must be solved. This requires full consideration of industry characteristics, water source conditions, water system matching, etc., to reduce the amount of concentrated brine, and at the same time utilize the characteristics of relevant production processes of the whole process of steel enterprises to achieve balanced consumption, thereby achieving water-salt balance in the entire circulation system. To this end, the present invention provides a concentrated brine treatment process for steel enterprises, which is characterized by comprising the following steps: 1) Brine hardness removal and separation: The brine discharged from industrial production is sent to the brine regulating tank at a rate of 80-100m 3 / h flow rate into the cooling equipment circulation water, and add hydrochloric acid at a rate of 500-800mg / L, adjust the pH value to 6-9, and then add 480-520m 3 / h flow rate to the hardness removal high-efficiency sedimentation unit, and add liquid alkali at a rate of 1500-2000mg / L to adjust the water hardness to less than 300mg / L. Then the sedimentation treatment is carried out for 30-50h to separate the sludge and brine. 3 / h to send the sludge to the sludge treatment station; 2) Pretreatment of separated brine: Step 1) Separate the brine by precipitation at 490-510m 3 / h flow rate to the high-density water outlet pool, adjust the pH value of the brine to 7-8, add sodium carbonate at a rate of 600-1000 mg / L to adjust the water hardness to less than 300 mg / L, add polyferric sulfate at a rate of 80-120 mg / L, add anion PAM at a rate of 0.5-1 mg / L to adjust the water turbidity, add sodium hypochlorite at a rate of 40-60 mg / L to adjust the residual chlorine, and then obtain pretreated brine; 3) Pre-treated brine ultrafiltration: The pre-treated brine in step 2) is filtered to 490-510 m 3 / h flow rate to the multi-media filter, the filtered sewage is 22-28m 3 / h flow rate returns to the concentrated brine regulating tank in step 1), and the filtered water is filtered at a rate of 450-490m 3 / h flow rate to the intermediate water tank, add 100-200mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L, add 50-100mg / L of hydrochloric acid to adjust the pH value to 6-9, and then send it to the ultrafiltration device at the same flow rate. The ultrafiltered sewage is filtered out at 45-50m 3 / h flow rate returns to the concentrated brine regulating tank in step 1); 4) Ultrafiltration water desalination: Step 3) The ultrafiltration water is 410-440m 3 / h flow rate to the ultrafiltration water production pool, add membrane antiscalant at 3-4mg / L, add non-oxidizing bactericide at 10-15mg / L, and add reducing agent at 4-6mg / L to control the residual chlorine in the water. Then send it to the first-stage reverse osmosis device for desalination at the same flow rate and 0.3-0.4Mpa pressure to control the inlet pH value of 7-8. The first-stage reverse osmosis water is 290-310m 3 / h flow rate is sent back to the water pool as water for cooling device; 5) Desalted water softening: Step 4) The concentrated water of the first-stage reverse osmosis is 120-130m 3 / h flow rate to the softening resin device, using ion exchange resin to remove calcium and magnesium ions in the water to obtain softened water, the pH value of the softened water is controlled to be 7-9, the total hardness is less than 50 mg / L, and the softened water is 5-7m 3 / h flow rate is used separately as recycled water; 6) Softened water chlorine control: Step 5) softened concentrated water at 120-130m 3 / h flow rate to the first-stage reverse osmosis concentrated water pool, add membrane antiscalant at 4-5mg / L, add non-oxidizing bactericide at 10-15mg / L, and add reducing agent at 4-6mg / L to control the residual chlorine in the water. Then send it to the second-stage reverse osmosis device at the same flow rate and 0.35-0.45Mpa pressure to control the inlet pH value of 7-8, hardness less than 10 mg / L, chloride ion content less than 150 mg / L, conductivity less than 900μs / cm, and the second-stage reverse osmosis water is 65-70m 3 / h flow rate is sent back to the water pool as water for cooling device; 7) Chlorine-controlled water consumption: Step 6) The concentrated water from the secondary reverse osmosis is 50-60m 3 / h is sent to the secondary reverse osmosis concentrate pool, and then sent to the subsequent process through the concentrate network at the same flow rate for disposal.

[0005] The membrane scale inhibitor is a commercial product produced by BWA (Bihua Water Treatment Additives) in the UK, and is used to inhibit scaling ions, colloids, etc. in water from forming scale on the concentrated water side. The injection rate G1 is calculated according to the following formula: G1 (kg / h) = dosage concentration × reverse osmosis water intake × 10 -3 .

[0006] The non-oxidizing bactericide is commercially available isothiazolinone produced by Jiangsu Baojin Biochemical Co., Ltd. and is used to prevent the formation of biofilm on the surface of the reverse osmosis membrane. The injection rate G2 is calculated according to the following formula: G2 (kg / time) = dosage concentration × reverse osmosis water intake × 10 -3 ×Time.

[0007] The reducing agent is commercially available NaHSO3, produced by Jiangsu Baojin Biochemical Co., Ltd., and is used to reduce the residual chlorine in the reverse osmosis inlet water to ensure that the residual chlorine entering the reverse osmosis system is approximately zero and prevent the residual chlorine from oxidizing the membrane element. The injection rate G3 is calculated according to the following formula: G3 (kg / h) = residual chlorine × 1.5 × reverse osmosis water intake.

[0008] The ultrafiltration membrane in the ultrafiltration device and the reverse osmosis membrane in the primary and secondary reverse osmosis devices are cleaned and descaled as usual, more than twice a month, to maintain the working performance of the membrane.

[0009] The present invention has the following advantages and effects: by adopting the above technical scheme, the amount of concentrated brine can be increased from 420m 3 / h reduced to 55m 3 / h, which is much lower than the concentrated brine absorption capacity of the blast furnace process of 83m 3 / h, which fully meets the full-process balance needs of steel enterprises under Class V water source conditions, and at the same time greatly improves the water quality of recycled water, improving the water quality of production water by more than 30%, and completely realizing zero discharge of brine; after zero discharge of brine is achieved, the conductivity of production water is improved from 3700μs / cm to 900μs / cm, an increase of 32%, laying a solid foundation for the stable operation of steel production equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0011] The present invention will be further described below in conjunction with embodiments.

[0012] The devices used in the embodiments of the present invention are all conventional equipment.

[0013] The products added in the embodiments of the present invention are all commercially available products, among which: The membrane scale inhibitor is a commercial product produced by BWA (Bihua Water Treatment Additives) in the UK, and is used to inhibit scaling ions, colloids, etc. in water from forming scale on the concentrated water side. The injection rate G1 is calculated according to the following formula: G1 (kg / h) = dosage concentration × reverse osmosis water intake × 10 -3 .

[0014] The non-oxidizing bactericide is commercially available isothiazolinone produced by Jiangsu Baojin Biochemical Co., Ltd. and is used to prevent the formation of biofilm on the surface of the reverse osmosis membrane. The injection rate G2 is calculated according to the following formula: G2 (kg / time) = dosage concentration × reverse osmosis water intake × 10 -3 ×Time.

[0015] The reducing agent is commercially available NaHSO3, produced by Jiangsu Baojin Biochemical Co., Ltd., and is used to reduce the residual chlorine in the reverse osmosis inlet water to ensure that the residual chlorine entering the reverse osmosis system is approximately zero and prevent the residual chlorine from oxidizing the membrane element. The injection rate G3 is calculated according to the following formula: G3 (kg / h) = residual chlorine × 1.5 × reverse osmosis water intake.

[0016] The ultrafiltration membrane in the ultrafiltration device and the reverse osmosis membrane in the primary and secondary reverse osmosis devices used in the embodiment of the present invention are cleaned and descaled as usual, and are cleaned more than twice a month to maintain the working performance of the membrane. Example 1

[0017] A concentrated brine treatment process for a steel enterprise comprises the following steps: 1) The concentrated brine discharged from industrial production is discharged at 420m 3 / h to the concentrated brine regulating pool, at 80-m3 / h flow rate into the cooling equipment circulation water, and add hydrochloric acid at a rate of 500mg / L, adjust the pH value to 6, and then 3 / h flow rate to the hardness removal high-efficiency sedimentation unit, and add 1500mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L. After the sedimentation treatment for 50h, the sludge and brine are separated by sedimentation. 3 / h to send the sludge to the sludge treatment station; 2) Step 1) The brine separated by precipitation is heated to 490m 3 / h flow rate to the high-density water outlet pool, adjust the pH value of the brine to 7, add sodium carbonate at a rate of 600 mg / L to adjust the water hardness to less than 300 mg / L, add polyferric sulfate at a rate of 80 mg / L, add anion PAM at a rate of 0.5 mg / L to adjust the water turbidity, add sodium hypochlorite at a rate of 40 mg / L to adjust the residual chlorine, and then obtain pretreated brine; 3) The pre-treated brine of step 2) is 490m 3 / h flow rate to the multi-media filter, the filtered sewage is sent to the multi-media filter at a rate of 22m 3 / h flow rate returns to the concentrated brine regulating tank in step 1), and the filtered water is filtered at 450m 3 / h flow rate to the intermediate water tank, add 100mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L, add 50mg / L of hydrochloric acid to adjust the pH value to 6, and then send it to the ultrafiltration device at the same flow rate. The ultrafiltered sewage is filtered out at 45m 3 / h flow rate returns to the concentrated brine regulating tank in step 1); 4) Step 3) The ultrafiltration water is 410m 3 / h flow rate to the ultrafiltration water production pool, add membrane antiscalant at 3mg / L, add non-oxidizing bactericide at 10mg / L, and add reducing agent at 4mg / L to control the residual chlorine in the water. Then send it to the first-stage reverse osmosis device for desalination at the same flow rate and 0.3Mpa pressure to control the inlet pH value of 7. The first-stage reverse osmosis water is produced at 290m 3 / h flow rate is sent back to the water pool as water for cooling device; 5) Step 4) The concentrated water from the first-stage reverse osmosis is 120m 3 / h flow rate to the softening resin device, using ion exchange resin to remove calcium and magnesium ions in the water to obtain softened water, the pH value of the softened water is controlled to be 7, the total hardness is less than 50 mg / L, and the softened water is 5m 3 / h flow rate is used separately as recycled water; 6) Step 5) The softened concentrated water is heated to 120m 3 / h flow rate to the first-stage reverse osmosis concentrated water pool, add membrane antiscalant at 4mg / L, add non-oxidizing bactericide at 10mg / L, and add reducing agent at 4mg / L to control the residual chlorine in the water. Then send it to the second-stage reverse osmosis device at the same flow rate and 0.35Mpa pressure to control the inlet pH value of 7, hardness less than 10 mg / L, chloride ion content less than 150 mg / L, conductivity less than 900μs / cm, and the second-stage reverse osmosis produced water at 65m 3 / h flow rate is sent back to the water pool as water for cooling device; 7) Step 6) The concentrated water from the secondary reverse osmosis is 50m 3 / h is sent to the secondary reverse osmosis concentrate pool, and then sent to the subsequent process through the concentrate network at the same flow rate for disposal.

[0018] Through this embodiment 1, the amount of concentrated brine is increased from 420m 3 / h reduced to 55m 3 / h, which is much lower than the concentrated brine absorption capacity of the blast furnace process of 83m 3 / h, fully meeting the full-process balance needs of steel enterprises under Class V water source conditions, while greatly improving the quality of recycled water and achieving zero discharge of brine. Example 2

[0019] A concentrated brine treatment process for a steel enterprise comprises the following steps: 1) The concentrated brine discharged from industrial production is discharged at 420m 3 / h is sent to the concentrated brine regulating pool, according to 100m 3 / h flow rate into the cooling equipment circulation water, and add hydrochloric acid at a rate of 800mg / L, adjust the pH value to 9, and then 3 / h flow rate to the hardness removal high-efficiency sedimentation unit, and add 2000mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L. Then the sedimentation treatment is carried out for 30h to separate the sludge and brine. 3 / h to send the sludge to the sludge treatment station; 2) Step 1) The brine separated by precipitation is 510m 3 / h flow rate to the high-density water outlet pool, adjust the pH value of the brine to 8, add sodium carbonate at a rate of 1000 mg / L to adjust the water hardness to less than 300 mg / L, add polyferric sulfate at a rate of 120 mg / L, add anion PAM at a rate of 1 mg / L to adjust the water turbidity, add sodium hypochlorite at a rate of 60 mg / L to adjust the residual chlorine, and then obtain pretreated brine; 3) The pre-treated brine in step 2) is 510 m 3 / h flow rate to the multi-media filter, the filtered sewage is sent to the multi-media filter at a rate of 28m 3The flow rate of / h is returned to the concentrated brine regulating tank in step 1), and the filtered water is filtered at 490m 3 / h flow rate to the intermediate water tank, add 200mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L, add 100mg / L of hydrochloric acid to adjust the pH value to 7, and then send it to the ultrafiltration device at the same flow rate. The ultrafiltered sewage is filtered out at 50m 3 / h flow rate returns to the concentrated brine regulating tank in step 1); 4) Step 3) The ultrafiltration water is 440m 3 / h flow rate to the ultrafiltration water production pool, add membrane antiscalant at 4mg / L, add non-oxidizing bactericide at 15mg / L, and add reducing agent at 6mg / L to control the residual chlorine in the water. Then send it to the first-stage reverse osmosis device for desalination at the same flow rate and 0.4Mpa pressure to control the inlet pH value of 8. The first-stage reverse osmosis water is 310m 3 / h flow rate is sent back to the water pool as water for cooling device; 5) Step 4) The concentrated water from the first-stage reverse osmosis is 130m 3 / h flow rate to the softening resin device, using ion exchange resin to remove calcium and magnesium ions in the water to obtain softened water, the pH value of the softened water is controlled to be 7, the total hardness is less than 50 mg / L, and the softened water is 7m 3 / h flow rate is used separately as recycled water; 6) Step 5) The softened concentrated water is heated to 130m 3 / h flow rate to the first-stage reverse osmosis concentrated water pool, add membrane antiscalant at 5mg / L, add non-oxidizing bactericide at 15mg / L, and add reducing agent at 6mg / L to control the residual chlorine in the water. Then send it to the second-stage reverse osmosis device at the same flow rate and 0.45Mpa pressure to control the inlet pH value of 7, hardness less than 10 mg / L, chloride ion content less than 150 mg / L, conductivity less than 900μs / cm, and the second-stage reverse osmosis produced water at 70m 3 / h flow rate is sent back to the water pool as water for cooling device; 7) Step 6) The concentrated water from the secondary reverse osmosis is 60m 3 / h is sent to the secondary reverse osmosis concentrate pool, and then sent to the subsequent process through the concentrate network at the same flow rate for disposal.

[0020] Through this embodiment 2, the amount of concentrated brine is increased from 420m 3 / h reduced to 59m 3 / h, which is much lower than the concentrated brine absorption capacity of the blast furnace process of 83m 3 / h, fully meeting the full-process balance needs of steel enterprises under Class V water source conditions, while greatly improving the quality of recycled water and achieving zero discharge of brine. Example 3

[0021] A concentrated brine treatment process for a steel enterprise comprises the following steps: 1) The concentrated brine discharged from industrial production is discharged at 420m 3 / h to the concentrated brine regulating pool, at 90m 3 / h flow rate into the cooling equipment circulation water, and add hydrochloric acid at a rate of 600mg / L, adjust the pH value to 8, and then add 495m 3 / h flow rate to the hardness removal high-efficiency sedimentation unit, and add 1800mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L. Then the sedimentation treatment is carried out for 40h to separate the sludge and brine. 3 / h to send the sludge to the sludge treatment station; 2) Step 1) The brine separated by precipitation is 500m 3 / h flow rate to the high-density water outlet pool, adjust the pH value of the brine to 8, add sodium carbonate at a rate of 800mg / L to adjust the water hardness to less than 300mg / L, add polyferric sulfate at a rate of 100mg / L, add anion PAM at a rate of 0.8mg / L to adjust the water turbidity, add sodium hypochlorite at a rate of 50mg / L to adjust the residual chlorine, and then obtain pretreated brine; 3) The pre-treated brine in step 2) is 500 m 3 / h flow rate to the multi-media filter, the filtered sewage is sent to the multi-media filter at a rate of 26m 3 The flow rate of / h is returned to the concentrated brine regulating tank in step 1), and the filtered water is filtered at 480m 3 / h flow rate to the intermediate water tank, add 110mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L, add 80mg / L of hydrochloric acid to adjust the pH value to 8, and then send it to the ultrafiltration device at the same flow rate. The ultrafiltered sewage is filtered out at 48m 3 / h flow rate returns to the concentrated brine regulating tank in step 1); 4) Step 3) The ultrafiltration water is 420m 3 / h flow rate to the ultrafiltration water production pool, add membrane antiscalant at 3.5mg / L, add non-oxidizing bactericide at 12mg / L, and add reducing agent at 5mg / L to control the residual chlorine in the water. Then send it to the first-stage reverse osmosis device for desalination at the same flow rate and 0.35Mpa pressure to control the inlet pH value of 7-8. The first-stage reverse osmosis water is produced at 298m 3 / h flow rate is sent back to the water pool as water for cooling device; 5) Step 4) The concentrated water from the first-stage reverse osmosis is 125m 3 / h flow rate to the softening resin device, using ion exchange resin to remove calcium and magnesium ions in the water to obtain softened water, the pH value of the softened water is controlled to be 8, the total hardness is less than 50 mg / L, and the softened water is 6m 3 / h flow rate is used separately as recycled water; 6) Step 5) The softened concentrated water is 127m 3 / h flow rate to the first-stage reverse osmosis concentrated water pool, add membrane antiscalant at 4.5mg / L, add non-oxidizing bactericide at 13mg / L, and add reducing agent at 4.5mg / L to control the residual chlorine in the water. Then send it to the second-stage reverse osmosis device at the same flow rate and 0.38Mpa pressure to control the inlet pH value of 7-8, hardness less than 10 mg / L, chloride ion content less than 150 mg / L, conductivity less than 900μs / cm, and the second-stage reverse osmosis produced water at 68m 3 / h flow rate is sent back to the water pool as water for cooling device; 7) Step 6) The concentrated water from the secondary reverse osmosis is 55m 3 / h is sent to the secondary reverse osmosis concentrate pool, and then sent to the subsequent process through the concentrate network at the same flow rate for disposal.

[0022] Through this embodiment 3, the amount of concentrated brine is increased from 420m 3 / h reduced to 57m 3 / h, which is much lower than the concentrated brine absorption capacity of the blast furnace process of 83m 3 / h, fully meeting the full-process balance needs of steel enterprises under Class V water source conditions, while greatly improving the quality of recycled water and achieving zero discharge of brine. Example 4

[0023] A concentrated brine treatment process for a steel enterprise comprises the following steps: 1) The concentrated brine discharged from industrial production is discharged at 420m 3 / h to the concentrated brine regulating pool, at 90m 3 / h flow rate into the cooling equipment circulation water, and add hydrochloric acid at a rate of 700mg / L, adjust the pH value to 9, and then 3 / h flow rate to the hardness removal high-efficiency sedimentation unit, and add 1850mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L. Then the sedimentation treatment is carried out for 38h to separate the sludge and brine. 3 / h to send the sludge to the sludge treatment station; 2) Step 1) The brine separated by precipitation is 498m 3 / h flow rate to the high-density water outlet pool, adjust the pH value of the brine to 8, add sodium carbonate at a rate of 800mg / L to adjust the water hardness to less than 300mg / L, add polyferric sulfate at a rate of 100mg / L, add anion PAM at a rate of 0.7mg / L to adjust the water turbidity, add sodium hypochlorite at a rate of 55mg / L to adjust the residual chlorine, and then obtain pretreated brine; 3) The pre-treated brine in step 2) is 498m 3 / h flow rate to the multi-media filter, the filtered sewage is sent to the multi-media filter at a rate of 26m 3 The flow rate of / h is returned to the concentrated brine regulating tank in step 1), and the filtered water is filtered at 470m 3 / h flow rate to the intermediate water tank, add 150mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L, add 70mg / L of hydrochloric acid to adjust the pH value to 6-9, and then send it to the ultrafiltration device at the same flow rate. The ultrafiltered sewage is filtered out at 46m 3 / h flow rate returns to the concentrated brine regulating tank in step 1); 4) Step 3) The ultrafiltration water is 430m 3 / h flow rate to the ultrafiltration water production pool, add membrane antiscalant at 3.2mg / L, add non-oxidizing bactericide at 14mg / L, and add reducing agent at 4.5mg / L to control the residual chlorine in the water. Then send it to the first-stage reverse osmosis device for desalination at the same flow rate and 0.36Mpa pressure to control the inlet pH value of 8. The first-stage reverse osmosis water is heated to 300m 3 / h flow rate is sent back to the water pool as water for cooling device; 5) Step 4) The concentrated water from the first-stage reverse osmosis is 128m 3 / h flow rate to the softening resin device, using ion exchange resin to remove calcium and magnesium ions in the water to obtain softened water, the pH value of the softened water is controlled to be 9, the total hardness is less than 50 mg / L, and the softened water is 6m 3 / h flow rate is used separately as recycled water; 6) Step 5) The softened concentrated water is 128m 3 / h flow rate to the first-stage reverse osmosis concentrated water pool, add membrane antiscalant at 4.6mg / L, add non-oxidizing bactericide at 14mg / L, and add reducing agent at 4.6mg / L to control the residual chlorine in the water. Then send it to the second-stage reverse osmosis device at the same flow rate and 0.42Mpa pressure to control the inlet pH value of 8, hardness less than 10 mg / L, chloride ion content less than 150 mg / L, conductivity less than 900μs / cm, and the second-stage reverse osmosis produced water at 68m 3 / h flow rate is sent back to the water pool as water for cooling device; 7) Step 6) The concentrated water from the secondary reverse osmosis is 57m3 / h is sent to the secondary reverse osmosis concentrate pool, and then sent to the subsequent process through the concentrate network at the same flow rate for disposal.

[0024] Through this embodiment 4, the amount of concentrated brine is increased from 420m 3 / h reduced to 56m 3 / h, which is much lower than the concentrated brine absorption capacity of the blast furnace process of 83m 3 / h, fully meeting the full-process balance needs of steel enterprises under Class V water source conditions, while greatly improving the quality of recycled water and achieving zero discharge of brine. Example 5

[0025] A concentrated brine treatment process for a steel enterprise comprises the following steps: 1) The concentrated brine discharged from industrial production is discharged at 420m 3 / h is sent to the concentrated brine regulating pool, according to 88m 3 / h flow rate into the cooling equipment circulation water, and add hydrochloric acid at a rate of 600mg / L, adjust the pH value to 7, and then add 488m 3 / h flow rate to the hardness removal high-efficiency sedimentation unit, and add 1800mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L. After the sedimentation treatment for 45h, the sludge and brine are separated by sedimentation. 3 / h to send the sludge to the sludge treatment station; 2) Step 1) The brine separated by precipitation is 499m 3 / h flow rate to the high-density water outlet pool, adjust the pH value of the brine to 7, add sodium carbonate at a rate of 700mg / L to adjust the water hardness to less than 300mg / L, add polyferric sulfate at a rate of 90mg / L, add anion PAM at a rate of 0.6mg / L to adjust the water turbidity, add sodium hypochlorite at a rate of 60mg / L to adjust the residual chlorine, and then obtain pretreated brine; 3) The pre-treated brine in step 2) is 510 m 3 / h flow rate to the multi-media filter, the filtered sewage is sent to the multi-media filter at a rate of 22m 3 The flow rate of / h is returned to the concentrated brine regulating tank in step 1), and the filtered water is filtered at 490m 3 / h flow rate to the intermediate water tank, add 100mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L, add 100mg / L of hydrochloric acid to adjust the pH value to 7, and then send it to the ultrafiltration device at the same flow rate. The ultrafiltered sewage is filtered out at 45m 3 / h flow rate returns to the concentrated brine regulating tank in step 1); 4) Step 3) The ultrafiltration water is 440m 3 / h flow rate to the ultrafiltration water production pool, add membrane antiscalant at 3-4mg / L, add non-oxidizing bactericide at 10mg / L, and add reducing agent at 6mg / L to control the residual chlorine in the water. Then send it to the first-stage reverse osmosis device for desalination at the same flow rate and 0.3Mpa pressure to control the inlet pH value of 7. The first-stage reverse osmosis water is 310m 3 / h flow rate is sent back to the water pool as water for cooling device; 5) Step 4) The concentrated water from the first-stage reverse osmosis is 130m 3 / h flow rate to the softening resin device, using ion exchange resin to remove calcium and magnesium ions in the water to obtain softened water, the pH value of the softened water is controlled to be 7, the total hardness is less than 50 mg / L, and the softened water is 5m 3 / h flow rate is used separately as recycled water; 6) Step 5) The softened concentrated water is heated to 120m 3 / h flow rate to the first-stage reverse osmosis concentrated water pool, add membrane antiscalant at 5mg / L, add non-oxidizing bactericide at 10mg / L, and add reducing agent at 6mg / L to control the residual chlorine in the water. Then send it to the second-stage reverse osmosis device at the same flow rate and 0.35Mpa pressure to control the inlet pH value of 7, hardness less than 10 mg / L, chloride ion content less than 150 mg / L, conductivity less than 900μs / cm, and the second-stage reverse osmosis produced water at 70m 3 / h flow rate is sent back to the water pool as water for cooling device; 7) Step 6) The concentrated water from the secondary reverse osmosis is 50m 3 / h is sent to the secondary reverse osmosis concentrate pool, and then sent to the subsequent process through the concentrate network at the same flow rate for disposal.

[0026] Through this embodiment 5, the amount of concentrated brine is increased from 420m 3 / h reduced to 58m 3 / h, which is much lower than the concentrated brine absorption capacity of the blast furnace process of 83m 3 / h, fully meeting the full-process balance needs of steel enterprises under Class V water source conditions, while greatly improving the quality of recycled water and achieving zero discharge of brine.

Claims

1. A process for treating concentrated brine in a steel enterprise, characterized in that The following steps are involved: 1) Brine hardness removal and separation: The brine discharged from industrial production is sent to the brine regulating tank at a rate of 80-100m 3 / h flow rate into the cooling equipment circulation water, and add hydrochloric acid at a rate of 500-800mg / L, adjust the pH value to 6-9, and then add 480-520m 3 / h flow rate to the hardness removal high-efficiency sedimentation unit, and add liquid alkali at a rate of 1500-2000mg / L to adjust the water hardness to less than 300mg / L. Then the sedimentation treatment is carried out for 30-50h to separate the sludge and brine. 3 / h to send the sludge to the sludge treatment station; 2) Pretreatment of separated brine: Step 1) Separate the brine by precipitation at 490-510m 3 / h flow rate to the high-density water outlet pool, adjust the pH value of the brine to 7-8, add sodium carbonate at a rate of 600-1000 mg / L to adjust the water hardness to less than 300 mg / L, add polyferric sulfate at a rate of 80-120 mg / L, add anion PAM at a rate of 0.5-1 mg / L to adjust the water turbidity, add sodium hypochlorite at a rate of 40-60 mg / L to adjust the residual chlorine, and then obtain pretreated brine; 3) Pre-treated brine ultrafiltration: The pre-treated brine in step 2) is filtered to 490-510 m 3 / h flow rate to the multi-media filter, the filtered sewage is 22-28m 3 / h flow rate returns to the concentrated brine regulating tank in step 1), and the filtered water is filtered at a rate of 450-490m 3 / h flow rate to the intermediate water tank, add 100-200mg / L of liquid caustic soda to adjust the water hardness to less than 300mg / L, add 50-100mg / L of hydrochloric acid to adjust the pH value to 6-9, and then send it to the ultrafiltration device at the same flow rate. The ultrafiltered sewage is filtered out at 45-50m 3 / h flow rate returns to the concentrated brine regulating tank in step 1); 4) Ultrafiltration water desalination: Step 3) The ultrafiltration water is 410-440m 3 / h flow rate to the ultrafiltration water production pool, add membrane antiscalant at 3-4mg / L, add non-oxidizing bactericide at 10-15mg / L, and add reducing agent at 4-6mg / L to control the residual chlorine in the water. Then send it to the first-stage reverse osmosis device for desalination at the same flow rate and 0.3-0.4Mpa pressure to control the inlet pH value of 7-8. The first-stage reverse osmosis water is 290-310m 3 / h flow rate is sent back to the water pool as water for cooling device; 5) Desalted water softening: Step 4) The concentrated water of the first-stage reverse osmosis is 120-130m 3 / h flow rate to the softening resin device, using ion exchange resin to remove calcium and magnesium ions in the water to obtain softened water, the pH value of the softened water is controlled to be 7-9, the total hardness is less than 50mg / L, and the softened water is 5-7m 3 / h flow rate is used separately as recycled water; 6) Softened water chlorine control: Step 5) softened concentrated water at 120-130m 3 / h flow rate to the first-stage reverse osmosis concentrated water pool, add membrane antiscalant at 4-5mg / L, add non-oxidizing bactericide at 10-15mg / L, and add reducing agent at 4-6mg / L to control the residual chlorine in the water. Then send it to the second-stage reverse osmosis device at the same flow rate and 0.35-0.45Mpa pressure to control the inlet pH value of 7-8, hardness less than 10 mg / L, chloride ion content less than 150 mg / L, conductivity less than 900μs / cm, and the second-stage reverse osmosis water is 65-70m 3 / h flow rate is sent back to the water pool as water for cooling device; 7) Chlorine-controlled water consumption: Step 6) The concentrated water from the secondary reverse osmosis is 50-60m 3 / h is sent to the secondary reverse osmosis concentrate pool, and then sent to the subsequent process through the concentrate network at the same flow rate for disposal.

2. The process for treating concentrated brine in a steel enterprise according to claim 1, characterized in that The membrane antiscalant is used to inhibit scaling ions, colloids, etc. in the water from forming scale on the concentrated water side. The injection rate G1 is calculated as follows: G1 (kg / h) = dosage concentration × reverse osmosis water intake × 10 -3 .

3. The process for treating concentrated brine in a steel enterprise according to claim 1, characterized in that The non-oxidizing bactericide is used to prevent the formation of biofilm on the surface of the reverse osmosis membrane, and its delivery rate G2 is calculated as follows: G2 (kg / time) = dosage concentration × reverse osmosis water intake × 10 -3 ×Time.

4. The process for treating concentrated brine in a steel enterprise according to claim 1, characterized in that The reducing agent is used to reduce the residual chlorine in the reverse osmosis water, ensuring that the residual chlorine entering the reverse osmosis system is approximately equal to zero, and preventing the residual chlorine from oxidizing the membrane element. The injection rate G3 is calculated according to the following formula: G3 (kg / h) = residual chlorine × 1.5 × reverse osmosis water intake.

5. The process for treating concentrated brine in a steel enterprise according to claim 1, characterized in that The ultrafiltration membrane in the ultrafiltration device and the reverse osmosis membrane in the primary and secondary reverse osmosis devices are cleaned and descaled as usual, more than twice a month, to maintain the working performance of the membrane.

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