Zero-discharge treatment system for high-salinity wastewater in smelting process

Abstract

The utility model provides a zero-discharge treatment system for high-salinity wastewater in a smelting process. Comprising an adjusting tank, a carbon removal device, a coagulative precipitation tank, a multi-medium filter, a resin softening device, an ultrafiltration device, a falling film concentration device, a sodium sulfate evaporative crystallization device, a freezing crystallization device, a nanofiltration device, a mixed salt evaporative crystallization device, an advanced oxidation device and a sodium chloride evaporative crystallization device. Wherein an oil removal device is mounted at the top of the regulating tank, hollow ball filler is contained in the carbon removal device, and a coagulation reaction area, a flocculation reaction area, an inclined tube clarification area, a sludge concentration area, a sludge backflow unit and a sludge discharge unit are arranged in the coagulation sedimentation tank. According to the utility model, pretreatment, nanofiltration salt separation and evaporative crystallization processes are adopted, so that the technical problems existing in zero-discharge treatment of the smelting wastewater can be effectively solved, and the device has the advantages of good salt separation effect, high salt quality, water production rate of more than 93%, impurity salt rate of less than 3%, low steam consumption, low treatment cost per ton of water, high automation degree and the like.

Description

TECHNICAL FIELD

[0001] The utility model belongs to high salt wastewater treatment technical field relates to a kind of smelting process high salt wastewater zero discharge treatment system. BACKGROUND

[0002] A large amount of heavy metal high-salt wastewater is generated in the non-ferrous smelting process. The wastewater is a mixed salt wastewater of sodium sulfate and sodium chloride, which has the characteristics of high salt content (TDS>170g / L), high alkalinity, high calcium and magnesium, high COD, complex composition, high impurity concentration, close salt-nitrate ratio, and difficult to separate salt. Improper treatment can cause serious environmental pollution. In recent years, with the continuous expansion of production scale and the continuous improvement of production capacity, the discharge of high-salt wastewater in non-ferrous smelting industry has also increased, and the zero discharge treatment of high-salt wastewater has become an inevitable trend. Therefore, the utility model provides a smelting process high-salt wastewater zero discharge treatment device. SUMMARY

[0003] The utility model aims at the problems existing in the prior art, and provides a smelting process high-salt wastewater zero discharge treatment system, which solves the problem of environmental pollution caused by the discharge of high-salt wastewater, and the problem of inefficient recycling of water resources and salt products.

[0004] Therefore, the utility model takes the following technical solutions:

[0005] A smelting process high-salt wastewater zero discharge treatment system, comprising a conditioning tank, a carbon removal device, a coagulation sedimentation tank, a multi-media filter, a resin softening device, an ultrafiltration device, a falling film concentration device, a sodium sulfate evaporation crystallization device, a freeze crystallization device, a nanofiltration device, a mixed salt evaporation crystallization device, a high-level oxidation device, and a sodium chloride evaporation crystallization device.

[0006] The output end of the conditioning tank is connected to the input end of the carbon removal device. The conditioning tank is used to remove the total alkalinity in the wastewater, reducing the total alkalinity from 5000-7000mg / L to 50-100mg / L.

[0007] The output end of the coagulation sedimentation tank is connected to the input end of the multi-media filter. The coagulation sedimentation tank is used to remove suspended solids and colloidal substances in the wastewater, reducing the suspended solids in the wastewater from 200-400mg / L to 5mg / L.

[0008] The output end of the multi-media filter is connected to the input end of the resin softening device. The multi-media filter is used as a security measure to further remove calcium and magnesium ions and heavy metal ions that have not been completely removed at the front end, reducing the calcium and magnesium hardness ions to below 2mg / L.

[0009] The output end of the resin softening device is connected to the input end of the ultrafiltration device, and the resin softening device is used to further remove fine suspended solids in the wastewater, so that the turbidity of the produced water is below 0.2 NTU.

[0010] The output end of the ultrafiltration device is connected to the input end of the falling film concentration device, and the ultrafiltration device is evaporated by the falling film concentration to increase the TDS of the wastewater from 175663 mg / L to 240000 mg / L, the evaporation water amount is 60-80 t / h, the chloride concentration is increased from 49046 mg / L to 67010 mg / L, and the sulfate concentration is concentrated from 63892 mg / L to 87293 mg / L.

[0011] The output end of the falling film concentration device is connected to the input end of the sodium sulfate evaporation crystallization device, and the falling film concentration device is used to produce sodium sulfate products with a purity of ≥99% through evaporation crystallization.

[0012] The output end of the sodium sulfate evaporation crystallization device is connected to the input end of the freeze crystallization device, and the freeze crystallization device produces Glauber's salt by freezing, returns to the sodium sulfate evaporation crystallization device, and then produces sodium sulfate products to reduce the concentration of sodium sulfate in the wastewater and increase the salt-nitrate ratio. The concentration of sulfate ions is reduced from 43798 mg / L to 16901 mg / L.

[0013] The output end of the freeze crystallization device is connected to the input end of the nanofiltration device, and the nanofiltration device separates sulfate and chloride. The nanofiltration water side has a chloride ion concentration of 130074-130599 mg / L and a sulfate ion concentration of 440-441 mg / L. The nanofiltration concentrated water side has a chloride ion concentration of 84965-85401 mg / L and a sulfate ion concentration of 51671-51753 mg / L.

[0014] The output end of the nanofiltration device is connected to the input end of the advanced oxidation device and the mixed salt evaporation crystallization device. The advanced oxidation device is used to remove organic matter in the wastewater, and the mixed salt evaporation crystallization device is used to produce part of the mixed salt. The COD is reduced from 968 mg / L to 193.6 mg / L.

[0015] The output end of the advanced oxidation device is connected to the input end of the sodium chloride evaporation crystallization device, and the sodium chloride evaporation crystallization device is used to evaporate and crystallize sodium chloride products with a purity of ≥98.5%.

[0016] Further, an oil removal device is installed at the top of the adjusting tank, and the input high-salt wastewater is subjected to oil removal by adding reagents and blowing air. The oil content of the wastewater is reduced from 10 ppm to 1 ppm.

[0017] Further, the carbon removal device contains hollow ball fillers inside, and the total alkalinity in the wastewater is removed by acid stripping.

[0018] Further, the coagulation sedimentation tank is internally provided with a coagulation reaction zone, a flocculation reaction zone, an inclined tube clarification zone, a sludge concentration zone, a sludge backflow unit and a sludge discharge unit.

[0019] Further, the ultrafiltration device adopts an external pressure type hollow fiber ultrafiltration membrane element, and the filter membrane material adopts PVDF.

[0020] Further, the nanofiltration device is two-stage two-section nanofiltration, the nanofiltration membrane flux is ≤13 L / m 2 h, the recovery rate is ≤75%, wherein the water produced by the first-stage nanofiltration enters the second-stage nanofiltration system, and the concentrated water of the two-stage nanofiltration enters the advanced oxidation device.

[0021] Further, the advanced oxidation device adopts a BDD electrochemical oxidation equipment, and the COD removal rate is above 80%.

[0022] Further, the flushing wastewater outlets of the multi-medium filter, the resin softening device, the ultrafiltration device and the nanofiltration device are connected with the water inlet of the adjusting tank.

[0023] Further, the falling film concentration device, the sodium sulfate evaporation crystallization device and the sodium chloride evaporation crystallization device all adopt MVR evaporators.

[0024] The beneficial effects of the utility model lie in:

[0025] The utility model adopts a pretreatment + nanofiltration salt separation + evaporation crystallization process, can effectively solve the technical problems existing in the zero discharge treatment of smelting wastewater, has the advantages of good salt separation effect, high salt quality, water production rate above 93%, low impure salt rate, low steam consumption, low ton water treatment cost and high automation degree. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a structural schematic view of the utility model.

[0027] In the figure, 1 is an adjusting tank, 2 is a carbon remover, 3 is a coagulation sedimentation tank, 4 is a multi-medium filter, 5 is a resin softening device, 6 is an ultrafiltration device, 7 is a falling film concentration device, 8 is a sodium sulfate evaporation crystallization device, 9 is a refrigeration crystallization device, 10 is a nanofiltration device, 11 is a mixed salt evaporation crystallization device, 12 is an advanced oxidation device and 13 is a sodium chloride evaporation crystallization device. DETAILED DESCRIPTION

[0028] The technical scheme of the utility model will be described in connection with the drawings and implementation methods.

[0029] For example, Figure 1As shown, a smelting process high-salt wastewater zero discharge treatment system includes a conditioning tank 1, a carbon removal device 2, a coagulation sedimentation tank 3, a multi-medium filter 4, a resin softening device 5, an ultrafiltration device 6, a falling film concentration device 7, a sodium sulfate evaporation crystallization device 8, a freezing crystallization device 9, a nanofiltration device 10, a mixed salt evaporation crystallization device 11, a high-level oxidation device 12, and a sodium chloride evaporation crystallization device 13.

[0030] The input end of the carbon removal device 2 is connected to a medicament and air is blown in to remove oil from the input high-salt wastewater, and the oil content of the wastewater is reduced from 10 ppm to 1 ppm.

[0031] The input end of the coagulation sedimentation tank 3 is connected to the output end of the carbon removal device 2, the carbon removal device 2 contains hollow ball fillers inside, the coagulation sedimentation tank 3 removes heavy metals and calcium and magnesium hardness in the wastewater by adding medicaments, the main heavy metal ions in the wastewater are reduced from 20-25 mg / L to 1.0 mg / L, the magnesium ion hardness is reduced from 5000 mg / L to 5 mg / L, and the calcium ion hardness is reduced from 50-200 mg / L to 20 mg / L.

[0032] The input end of the multi-medium filter 4 is connected to the output end of the coagulation sedimentation tank 3; the coagulation sedimentation tank 3 is provided with a coagulation reaction zone, a flocculation reaction zone, an inclined tube clarification zone, a sludge concentration zone, a sludge backflow unit, and a sludge discharge unit; the multi-medium filter 4 is used to remove suspended solids and colloidal substances in the wastewater, so that the suspended solids in the wastewater are reduced from 200-400 mg / L to 5 mg / L.

[0033] The input end of the resin softening device 5 is connected to the output end of the multi-medium filter 4, the resin softening device 5 is used as a safety measure to further remove calcium and magnesium ions and heavy metal ions that have not been completely removed at the front end, so that the calcium and magnesium hardness ions are reduced to below 2 mg / L.

[0034] The input end of the ultrafiltration device 6 is connected to the output end of the resin softening device 5, and the ultrafiltration device 6 is used to further remove fine suspended solids in the wastewater, so that the turbidity of the produced water is below 0.2 NTU.

[0035] The input end of the falling film concentration device 7 is connected to the output end of the ultrafiltration device 6; specifically, the ultrafiltration device 6 adopts an external pressure type hollow fiber ultrafiltration membrane element, and the filter membrane material adopts PVDF; the falling film concentration device 7 increases the TDS of the wastewater from 175663 mg / L to 240000 mg / L through falling film concentration evaporation, the evaporation water quantity is 60-80 t / h, the chloride concentration is increased from 49046 mg / L to 67010 mg / L, and the sulfate concentration is concentrated from 63892 mg / L to 87293 mg / L.

[0036] The input end of the sodium sulfate evaporation crystallization device 8 is connected to the output end of the falling film concentration device 7, and the sodium sulfate evaporation crystallization device 8 is used to produce sodium sulfate products with a purity of ≥99% through evaporation crystallization.

[0037] The output end of the freeze crystallization device 9 is connected with the input end of the nanofiltration device 10, the nanofiltration device 10 separates sulfate and chloride, the nanofiltration water side has a chloride ion concentration of 130074-130599 mg / L and a sulfate ion concentration of 440-441 mg / L, and the nanofiltration concentrated water side has a chloride ion concentration of 84965-85401 mg / L and a sulfate ion concentration of 51671-51753 mg / L.

[0038] The output end of the nanofiltration device 10 is connected with the input end of the advanced oxidation device 12 and the mixed salt evaporation crystallization device 11; the nanofiltration device 10 is two-stage two-section nanofiltration, the nanofiltration membrane flux is less than or equal to 13 L / m 2 .h, and the recovery rate is less than or equal to 75%, wherein the first-stage nanofiltration water enters the second-stage nanofiltration system, and the two-stage nanofiltration concentrated water enters the advanced oxidation device 12; the advanced oxidation device 12 adopts a BDD electrochemical oxidation equipment, the advanced oxidation device 12 is used for removing organic matters in the wastewater, the mixed salt evaporation crystallization device 11 is used for producing part of mixed salt, the output end of the advanced oxidation device 12 is connected with the input end of the sodium chloride evaporation crystallization device 13, and the sodium chloride evaporation crystallization device 13 is used for evaporating and crystallizing to produce sodium chloride products with a purity of greater than or equal to 98.5%.

[0039] The flushing wastewater outlets of the multi-medium filter 4, the resin softening device 5, the ultrafiltration device 6 and the nanofiltration device 10 are connected with the water inlet of the adjusting tank 1.

[0040] The falling film concentration device 7, the sodium sulfate evaporation crystallization device 8 and the sodium chloride evaporation crystallization device 13 all adopt MVR evaporators.

[0041] The application process of the utility model is as follows:

[0042] Step 1: the high-salinity wastewater enters the adjusting tank 1, most of the oil, part of the organic matters and the suspended matters in the water are removed through the oil removal device at the top of the adjusting tank 1, then the wastewater enters the carbon remover 2, the total alkalinity in the wastewater is reduced by adjusting pH and stripping, and then enters the coagulation sedimentation tank 3;

[0043] Step 2: the chemical reagent is added in the coagulation reaction area of the coagulation sedimentation tank 3, and the flocculating agent is added in the flocculation reaction area, most of the heavy metal ions and the calcium and magnesium hardness ions are removed through the chemical reaction, the quality of the crystalline salt in the subsequent system is ensured, and the water outlet of the coagulation sedimentation tank 3 enters the multi-medium filter 4, the resin softening device 5 and the ultrafiltration device 6 in sequence after pH readjustment;

[0044] Step 3: the suspended matters, the colloidal matters and the residual hardness and heavy metal ions in the wastewater are removed in sequence through the multi-medium filter 4, the resin softening device 5 and the ultrafiltration device 6; wherein the backwashing water of the multi-medium filter 4, the resin softening device 5 and the ultrafiltration device 6 returns to the adjusting tank 1;

[0045] Step 4: The water produced by the ultrafiltration device 6 is lifted by a feed pump and sequentially enters a plate preheater in series, and after preheating, the material enters a falling film concentration device 7 for evaporation and concentration, and then enters a sodium sulfate evaporation crystallization device 8; after the waste water is concentrated to a certain concentration, it is sent into a thickener by a crystal slurry pump, and then enters a centrifuge to separate sodium sulfate crystals, which are dried in a fluidized bed dryer, and then enter a sodium sulfate packaging system, producing an industrial sodium sulfate product with a purity of ≥99.0%;

[0046] Step 5: The mother liquor of the sodium sulfate evaporation crystallization device 8 and part of the concentrated water produced by the nanofiltration device 10 enter the freeze crystallization device 9 to produce glauber salt, which is sent to a glauber salt centrifuge after passing through a glauber salt settler, and the glauber salt after centrifugal dewatering is returned to the sodium sulfate evaporation crystallization device 8 for continuous evaporation and crystallization to produce sodium sulfate products;

[0047] Step 6: The mother liquor of the freeze crystallization device 9 enters the nanofiltration device 10, which uses the selective permeability of the nanofiltration membrane to intercept divalent ions and part of the organic matter, allowing monovalent ions to pass through, thereby efficiently separating sodium chloride and sodium sulfate to ensure the purity of sodium chloride entering the sodium chloride evaporation crystallization device 13, and the nanofiltration water enters the advanced oxidation device 12, and part of the concentrated water returns to the freeze crystallization device 9 and part enters the mixed salt evaporation crystallization device 11;

[0048] Step 7: The nanofiltration water enters the advanced oxidation device 12, which removes organic matter in the nanofiltration water through an electro-catalytic oxidation device to improve the quality of sodium chloride salt, and the water from the advanced oxidation device 12 enters the sodium chloride evaporation crystallization device, and after the sodium chloride is concentrated to a certain concentration, it is sent into a thickener by a crystal slurry pump, and then enters a centrifuge to separate sodium chloride crystals, which are dried in a fluidized bed dryer, and then enter a sodium chloride packaging system, producing a sodium chloride product with a purity of ≥98.5%;

[0049] Step 8: The sodium chloride mother liquor and part of the nanofiltration concentrated water are mixed into the mixed salt evaporation crystallization device 11 to further evaporate and concentrate the concentrated liquid, crystallize most of the sodium chloride and part of the sodium sulfate, and after thickening and centrifugal separation, return to the nanofiltration device 10 for recycling to separate and recover sodium chloride and sodium sulfate again, improve the resource utilization rate of crystalline salt, and the evaporation condensate produced by evaporation and crystallization enters a reuse water pool and is returned to the production system for reuse. The regenerated salt produced by evaporation and crystallization is used for resource utilization.

Claims

1. A smelting process high-salinity wastewater zero-emission treatment system, characterized in that, The device comprises an adjusting tank (1), a carbon removal device (2), a coagulation sedimentation tank (3), a multi-medium filter (4), a resin softening device (5), an ultrafiltration device (6), a falling film concentration device (7), a sodium sulfate evaporation crystallization device (8), a freezing crystallization device (9), a nanofiltration device (10), a mixed salt evaporation crystallization device (11), an advanced oxidation device (12), and a sodium chloride evaporation crystallization device (13). The input end of the carbon removal device (2) is connected to the output end of the adjusting tank (1), and the carbon removal device (2) is used for removing total alkalinity in the wastewater, reducing the total alkalinity of the wastewater from 5000-7000 mg / L to 50-100 mg / L. The input end of the coagulation sedimentation tank (3) is connected to the output end of the carbon removal device (2), and the coagulation sedimentation tank (3) removes heavy metals and calcium and magnesium hardness in the wastewater by adding reagents, and the main heavy metal ions in the wastewater are reduced from 20-25 mg / L to 1.0-2.0 mg / L, the magnesium ion hardness is reduced from 5000 mg / L to 5-8 mg / L, and the calcium ion hardness is reduced from 50-200 mg / L to 20-30 mg / L. The input end of the multi-medium filter (4) is connected to the output end of the coagulation sedimentation tank (3), and the multi-medium filter (4) is used for removing suspended solids and colloidal substances in the wastewater, so that the suspended solids in the wastewater are reduced from 200-400 mg / L to 5-10 mg / L. The input end of the resin softening device (5) is connected to the output end of the multi-medium filter (4), and the resin softening device (5) is used for further removing calcium and magnesium ions and heavy metal ions that are not completely removed at the front end, so that the calcium and magnesium hardness ions are reduced to below 2 mg / L. The input end of the ultrafiltration device (6) is connected to the output end of the resin softening device (5), and the ultrafiltration device (6) is used for further removing fine suspended solids in the wastewater, so that the turbidity of the produced water is below 0.2 NTU. The input end of the falling film concentration device (7) is connected to the output end of the ultrafiltration device (6), and the falling film concentration device (7) increases the TDS of the wastewater from 170000-180000 mg / L to 240000-290000 mg / L through falling film concentration evaporation, the evaporation water amount is 60-80 t / h, the chloride concentration is increased from 49000-50000 mg / L to 67010-70000 mg / L, and the sulfate concentration is concentrated from 63892-70000 mg / L to 87293-90000 mg / L. The input end of the sodium sulfate evaporation crystallization device (8) is connected to the output end of the falling film concentration device (7), and the sodium sulfate evaporation crystallization device (8) is used for producing sodium sulfate products with a purity of ≥99% through evaporation crystallization. The output end of the sodium sulfate evaporation crystallization device (8) is connected to the input end of the freezing crystallization device (9), and the freezing crystallization device (9) produces Glauber's salt through freezing, returns to the sodium sulfate evaporation crystallization device (8), and then produces sodium sulfate products, so as to reduce the concentration of sodium sulfate in the wastewater and improve the salt-nitrate ratio, and the sulfate ion concentration is reduced from 43000-50000 mg / L to 16000-18000 mg / L. The output end of the freezing crystallization device (9) is connected to the input end of the nanofiltration device (10), the nanofiltration device (10) separates sulfate and chloride, the nanofiltration water side has a chloride ion concentration of 130074-130599 mg / L, a sulfate ion concentration of 440-441 mg / L, the nanofiltration concentrated water side has a chloride ion concentration of 84965-85401 mg / L, and a sulfate ion concentration of 51671-51753 mg / L; The output end of the nanofiltration device (10) is connected to the input end of the advanced oxidation device (12) and the mixed salt evaporation crystallization device (11), the mixed salt evaporation crystallization device (11) is used to produce part of the mixed salt, and the advanced oxidation device (12) is used to remove the organic matter in the wastewater, and the COD is reduced from 968-1200 mg / L to 190-200 mg / L; The output end of the advanced oxidation device (12) is connected to the input end of the sodium chloride evaporation crystallization device (13), and the sodium chloride evaporation crystallization device (13) is used to evaporate and crystallize to produce sodium chloride products with a purity of greater than or equal to 98.5%.

2. The system for zero discharge of high salinity wastewater from a smelting process according to claim 1, wherein, An oil removal device is installed on the top of the adjusting tank (1), and the high-salt wastewater is subjected to oil removal by adding reagents and blowing air, and the oil content of the wastewater is reduced from 10-15 ppm to 1-5 ppm.

3. The system for zero discharge of high salinity wastewater from a smelting process according to claim 1, wherein, The carbon removal device (2) contains hollow ball fillers, and the total alkalinity in the wastewater is removed by acid blowing.

4. The system for zero discharge of high salinity wastewater from a smelting process according to claim 1, wherein, The coagulation sedimentation tank (3) is provided with a coagulation reaction zone, a flocculation reaction zone, an inclined tube clarification zone, a sludge concentration zone, a sludge reflux unit and a sludge discharge unit.

5. The system for zero liquid discharge of high salinity wastewater from a smelting process according to claim 1, wherein, The ultrafiltration device (6) adopts an external pressure type hollow fiber ultrafiltration membrane element, and the filter membrane material adopts PVDF.

6. The system for zero liquid discharge of high salinity wastewater from a smelting process according to claim 1, wherein, The nanofiltration device (10) is two-stage two-section nanofiltration, and the nanofiltration membrane flux is ≤13 L / m 2 .h, and the recovery rate is ≤75%, wherein the water produced by the first-stage nanofiltration enters the second-stage nanofiltration system, and the concentrated water of the two-stage nanofiltration enters the advanced oxidation device (12).

7. The system for zero liquid discharge of high salinity wastewater from a smelting process according to claim 1, wherein, The advanced oxidation device (12) adopts a BDD electrochemical oxidation device, and the COD removal rate is more than 80%.

8. The system for zero liquid discharge of high salinity wastewater from a smelting process according to claim 1, wherein, The flushing wastewater outlets of the multi-medium filter (4), the resin softening device (5), the ultrafiltration device (6) and the nanofiltration device (10) are connected to the water inlet of the adjusting tank (1).

9. The system for zero liquid discharge of high salinity wastewater from a smelting process according to claim 1, wherein, The falling film concentration device (7), the sodium sulfate evaporation crystallization device (8) and the sodium chloride evaporation crystallization device (13) all adopt MVR evaporators.

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