Method and device for combined treatment of battery crushing wastewater and ferrophosphorus synthesis wastewater

Abstract

The invention provides a method and device for combined treatment of battery crushing wastewater and ferrophosphorus synthesis wastewater, and the method comprises the following steps: (1) mixing the battery crushing wastewater and the ferrophosphorus synthesis wastewater, and carrying out acidolysis treatment on the obtained mixed wastewater to obtain acidolysis wastewater; (2) carrying out first pH regulation on the acidolysis wastewater obtained in the step (1), mixing with a phosphorus source, and recovering lithium to obtain a first liquid phase; (3) sequentially carrying out impurity removal and second pH adjustment on the first liquid phase in the step (2) to obtain a second liquid phase; (4) carrying out catalytic oxidation treatment on the second liquid phase in the step (3) to obtain a liquid phase without organic matters; and (5) dehydrating the organic matter-removed liquid phase obtained in the step (4) to obtain a sodium sulfate product. According to the method, the purposes of treating waste with waste and saving treatment cost can be achieved while the acid use amount is reduced, the lithium recovery rate in the whole battery recovery process is increased, the economic value is high, and the application prospect is wide.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method and a device for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. Background Art

[0002] In the wet recycling process of waste lithium iron phosphate batteries, the waste batteries need to be disassembled, discharged, and crushed, etc., which can be used to recycle lithium carbonate on the one hand and iron phosphate on the other. The battery crushing process will produce high-salt and high-organic wastewater, which contains high-concentration salt, organic matter, and difficult-to-degrade electrolyte salts. Conventional calcium addition methods cannot remove the organic phosphorus and organic fluorine contained in the wastewater, and high-salt wastewater is directly discharged without treatment, which will cause land salinization; the iron phosphate recovery process will produce a large amount of acidic synthetic wastewater, and the treatment of such wastewater requires a large amount of calcium-containing agents, which has high treatment costs and large waste residue output.

[0003] At present, for the treatment of these two types of wastewater, the MVR evaporation method can only evaporate salt. When the organic matter is too high, it is necessary to add an organic matter removal device, otherwise it is easy to bubble up and affect the product quality. Common methods for removing organic matter include catalytic oxidation, biochemical method, extraction method, activated carbon adsorption method, etc., which can be used in conjunction with the MVR evaporation method to remove COD and salt, but the organic phosphorus and organic fluorine in the wastewater cannot be removed. Common methods for removing fluorine and phosphorus include resin method, special removal agents, etc., but the resin method is costly and requires regular regeneration and replacement, and the special removal agent is not suitable for industrial mass production.

[0004] Therefore, how to efficiently remove organic matter, organic phosphorus, organic fluorine and soluble salts in wastewater, reduce wastewater treatment costs and slag disposal costs, and achieve zero wastewater discharge is a problem that urgently needs to be improved and solved. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method and device for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. The present invention can efficiently remove organic matter, organic phosphorus, organic fluorine and soluble salts in the wastewater, reduce the cost of wastewater treatment and waste residue disposal, and achieve zero wastewater discharge.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater, the method comprising:

[0008] (1) mixing battery crushing wastewater and ferrophosphorus synthesis wastewater, and subjecting the obtained mixed wastewater to acid hydrolysis treatment to obtain acid-hydrolyzed wastewater;

[0009] (2) The wastewater after acid hydrolysis in step (1) is subjected to a first pH adjustment, mixed with a phosphorus source, and lithium is recovered to obtain a first liquid phase;

[0010] (3) Step (2) wherein the first liquid phase is subjected to sequential impurity removal and second pH adjustment to obtain a second liquid phase;

[0011] (4) The second liquid phase in step (3) is subjected to catalytic oxidation treatment to obtain a liquid phase after organic matter is removed;

[0012] (5) After removing the organic matter in step (4), the liquid phase is dehydrated to obtain a sodium sulfate product.

[0013] The method provided by the present invention adopts the "high temperature acid hydrolysis" process, which can efficiently break the difficult-to-break PF bonds in the electrolyte wastewater, decompose them into orthophosphate and fluoride ions, and then remove them by conventional calcium method, overcoming the industry problem that the traditional calcium method, aluminum method, etc. cannot effectively remove phosphorus and fluoride from the electrolyte wastewater. And the method of combining electrolyte wastewater with acidic wastewater greatly reduces the amount of acid used, while achieving the purpose of treating waste with waste and saving disposal costs.

[0014] Preferably, the pH value of the battery crushing wastewater in step (1) is 2 to 4, for example, it can be 2, 2.3, 2.5, 2.7, 2.9, 3.2, 3.4, 3.6, 3.8 or 4.

[0015] Preferably, the COD of the battery crushing wastewater is 20000-60000 mg / L, for example, it can be 20000 mg / L, 24400 mg / L, 28800 mg / L, 33300 mg / L, 37700 mg / L, 42200 mg / L, 46600 mg / L, 51100 mg / L, 55500 mg / L or 60000 mg / L, etc.

[0016] Preferably, the composition of the battery crushing wastewater includes SO4 2- :80~100g / L,F - :2000~3000mg / L,TP:5000~10000mg / L and Li + :5000~10000mg / L.

[0017] Among them, SO4 2- : 80-100 g / L, for example, it can be 80 g / L, 83 g / L, 85 g / L, 87 g / L, 89 g / L, 92 g / L, 94 g / L, 96 g / L, 98 g / L or 100 g / L, etc.

[0018] F -: 2000-3000 mg / L, for example, it can be 2000 mg / L, 2110 mg / L, 2220 mg / L, 2330 mg / L, 2440 mg / L, 2550 mg / L, 2660 mg / L, 2770 mg / L, 2880 mg / L or 3000 mg / L, etc.

[0019] TP: 5000-10000 mg / L, for example, it can be 5000 mg / L, 5500 / L, 6100 / L, 6600 / L, 7200 / L, 7700 / L, 8300 / L, 8800 / L, 9400 / L or 10000 mg / L, etc.

[0020] Li + : 5000-10000 mg / L, for example, it can be 5000 mg / L, 5500 / L, 6100 / L, 6600 / L, 7200 / L, 7700 / L, 8300 / L, 8800 / L, 9400 / L or 10000 mg / L, etc.

[0021] Preferably, the composition of the ferric phosphate synthesis wastewater includes H + :1200~1400mg / L,SO4 2- :140~180g / L、F - : 2~10mg / L and TP: 200~4000mg / L.

[0022] Among them, H + : 1200-1400 mg / L, for example, it can be 1200 mg / L, 1220 g / L, 1245 mg / L, 1260 g / L, 1280 g / L, 1310 g / L, 1330 g / L, 1350 g / L, 1370 g / L or 1400 mg / L, etc.

[0023] SO4 2- : 140-180 g / L, for example, it can be 140 g / L, 145 g / L, 148 / L, 150 / L, 155 / L, 163 g / L, 165L, 170 / L, 175 / L or 180 g / L, etc.

[0024] F - : 2 to 10 mg / L, for example, it can be 2 mg / L, 2.9 mg / L, 3.8 mg / L, 4.7 mg / L, 5.6 mg / L, 6.5 mg / L, 7.4 mg / L, 8.3 mg / L, 9.2 mg / L or 10 mg / L, etc.

[0025] TP: 200-4000 mg / L, for example, it can be 200 mg / L, 620 g / L, 1040 g / L, 1400 / L, 1800 / L, 2300 / L, 2700 / L, 3100 / L, 3500 / L or 4000 mg / L, etc.

[0026] Preferably, the COD of the ferric phosphate synthetic wastewater is 20-40 mg / L, for example, it can be 20 mg / L, 23 mg / L, 25 mg / L, 27 mg / L, 29 mg / L, 32 mg / L, 34 mg / L, 36 mg / L, 38 mg / L or 40 mg / L.

[0027] Preferably, the COD of the mixed wastewater is 10000-30000 mg / L, for example, it can be 10000 mg / L, 12200 / L, 14400 / L, 16600 / L, 18800 / L, 21100 / L, 23300 / L, 25500 / L, 27700 / L or 30000 mg / L.

[0028] Preferably, the composition of the mixed wastewater includes SO4 2- :140~160g / L,F - :500~1500mg / L, TP: 1400~5000mg / L, Li + :1200~2000mg / L.

[0029] Among them, SO4 2- : 140-160g / L, for example, it can be 140g / L, 143g / L, 145g / L, 147g / L, 149g / L, 152g / L, 154g / L, 156g / L, 158g / L or 160g / L, etc.

[0030] F - : 500-1500 mg / L, for example, it can be 500 mg / L, 615 g / L, 725 g / L, 835 / L, 940 g / L, 1050 g / L, 1160 g / L, 1270 g / L, 1380 g / L or 1500 mg / L, etc.

[0031] TP: 1400-5000 mg / L, for example, it can be 1400 mg / L, 1800 mg / L, 2200 mg / L, 2600 mg / L, 3000 mg / L, 3400 mg / L, 3800 mg / L, 4200 mg / L, 4600 mg / L or 5000 mg / L, etc.

[0032] Li +: 1200-5000 mg / L, for example, it can be 1200 mg / L, 1880 g / L, 2370 g / L, 2960 g / L, 3550 g / L, 3745 mg / L, 4230 g / L, 4520 g / L, 4910 g / L or 5000 mg / L, etc.

[0033] Preferably, the pH of the mixed wastewater is 0-0.20, for example, 0, 0.1 or 0.2.

[0034] In the present invention, the pH of the mixed wastewater is preferably controlled within the above range, wherein active hydrogen migrates faster than lithium ions and combines with fluoride ions first, thereby promoting the reaction and having a better acid hydrolysis treatment effect.

[0035] Preferably, the volume ratio of the battery crushing wastewater to the acidic wastewater in step (1) is 1:1 to 1:5, for example, it can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, etc.

[0036] Preferably, the temperature of the acid hydrolysis treatment is 85-95°C, for example, it can be 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C or 95°C.

[0037] The present invention preferably controls the temperature of the acid hydrolysis treatment within the above range, wherein the combination rate of active hydrogen and fluoride ions is faster, resulting in a better acid hydrolysis treatment effect.

[0038] Preferably, the acid hydrolysis treatment time is 9 to 14 h, for example, it can be 9 h, 9.6 h, 10.2 h, 10.7 h, 11.3 h, 11.8 h, 12.4 h, 12.9 h, 13.5 h or 14 h.

[0039] Preferably, in step (2), the first step of adjusting the pH to a pH of 11 to 13, for example, 11, 11.3, 11.5, 11.7, 11.9, 12.2, 12.4, 12.6, 12.8 or 13, etc.

[0040] Preferably, the phosphorus source is sodium phosphate.

[0041] Preferably, the amount of the phosphorus source added is 3n(PO4 3- ): n(Li + )=0.9 to 1.5, for example, it can be 0.9, 0.97, 1.04, 1.1, 1.17, 1.24, 1.3, 1.37, 1.44 or 1.5.

[0042] The present invention preferably controls the amount of phosphorus source added to be within the range of 0.9 to 1.5 times the theoretical amount, which can better remove Li in wastewater. + .

[0043] Preferably, the reaction time for recovering lithium is 30 to 60 min, for example, it may be 30 min, 34 min, 37 min, 40 min, 44 min, 47 min, 50 min, 54 min, 57 min or 60 min.

[0044] Preferably, the impurity removal in step (3) comprises: mixing the first liquid phase and a calcium source to perform an impurity removal process.

[0045] Preferably, the calcium source is a calcium-containing compound, preferably calcium oxide and / or calcium hydroxide.

[0046] Preferably, the amount of the calcium source added is 0.9 to 1.5 times the theoretical amount, for example, it can be 0.9 times, 0.97 times, 1.04 times, 1.1 times, 1.17 times, 1.24 times, 1.3 times, 1.37 times, 1.44 times or 1.5 times, etc.

[0047] The present invention preferably controls the amount of calcium source added to be within the range of 0.9 to 1.5 times the theoretical amount, which can better remove F in wastewater. - .

[0048] Preferably, the reaction time in the impurity removal process is 1.5 to 3.0 h, for example, it can be 1.5 h, 1.7 h, 1.9 h, 2 h, 2.2 h, 2.4 h, 2.5 h, 2.7 h, 2.9 h or 3.0 h.

[0049] Preferably, PO4 is removed during the impurity removal process. 3- 、SO4 2- and F - .

[0050] Preferably, in step (3), the second step of adjusting the pH to a pH of 7 to 9, for example, 7, 7.3, 7.5, 7.7, 7.9, 8.2, 8.4, 8.6, 8.8 or 9.

[0051] The second step of adjusting pH in the present invention is mainly to control the pH of subsequent catalytic oxidation, so as to better achieve the decomposition of COD and the removal of organic matter.

[0052] Preferably, the operating voltage of the catalytic oxidation reactor in the catalytic oxidation treatment in step (4) is 4.00-5.10 V, for example, it can be 4.00 V, 4.13 V, 4.25 V, 4.37 V, 4.49 V, 4.62 V, 4.74 V, 4.86 V, 4.98 V or 5.10 V, etc.

[0053] Preferably, the current density of the catalytic oxidation reactor in the catalytic oxidation treatment is 40-50 mA / cm 2 , for example, it can be 40mA / cm 2 , 42mA / cm 2 , 43mA / cm 2 , 44mA / cm 2 , 45mA / cm 2 , 46mA / cm 2 , 47mA / cm 2 , 48mA / cm 2 , 49mA / cm 2 or 50mA / cm 2 wait.

[0054] Preferably, the motor speed of the catalytic oxidation reactor in the catalytic oxidation treatment is 250-300 r / min, for example, it can be 250 r / min, 256 r / min, 262 r / min, 267 r / min, 273 r / min, 278 r / min, 284 r / min, 288 / min, 295 r / min or 300 r / min, etc.

[0055] Preferably, the catalytic oxidation treatment time is 2.0 to 4.0 h, for example, it can be 2.0 h, 2.3 h, 2.5 h, 2.7 h, 2.9 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h or 4.0 h.

[0056] The preferred time for catalytic oxidation treatment in the present invention is within the above range, which can achieve efficient removal of COD in wastewater while taking into account wastewater treatment efficiency.

[0057] Preferably, the dehydration method in step (5) is evaporative dehydration.

[0058] Preferably, the evaporative dehydration method is MVR evaporative dehydration.

[0059] Preferably, the temperature of the MVR evaporation dehydration is 90-95°C, for example, 90°C, 90.6°C, 91.2°C, 91.7°C, 92.3°C, 92.8°C, 93.4°C, 93.9°C, 94.5°C or 95°C.

[0060] As a preferred technical solution of the present invention, the method comprises the following steps:

[0061] (1) Battery crushing wastewater and ferrophosphorus synthesis wastewater are mixed in a volume ratio of 1:1 to 1:5 to obtain mixed wastewater (COD is 10000 to 30000 mg / L, and the composition includes SO4 2-: 140~160g / L, F-: 500~1500mg / L, TP: 1400~5000mg / L, Li + : 1200-5000 mg / L, pH 0-0.20), acid hydrolysis treatment at 85-95°C for 9-14 hours to obtain acid hydrolysis wastewater;

[0062] (2) The wastewater after acid hydrolysis in step (1) is first adjusted to a pH of 11 to 13, and then 3n(PO4 3- ): n(Li + )=0.9~1.5, add sodium phosphate, carry out lithium precipitation reaction for 30~60min to recover lithium, and obtain the first liquid phase;

[0063] (3) Mix the first liquid phase and the calcium source, the amount of calcium source added is 0.9 to 1.5 times the theoretical amount, and perform impurity removal for 1.5 to 3.0 hours to remove PO4 3- 、SO4 2- and F - , then adjusting the pH to pH 7-9 to obtain a second liquid phase;

[0064] (4) Step (3) The second liquid phase is subjected to catalytic oxidation treatment, and the operating voltage of the catalytic oxidation reactor is 4.00-5.10 V, and the current density is 40-50 mA / cm 2 , the motor speed is 250-300r / min, the time is 2.0-4.0h, and the liquid phase after removing the organic matter is obtained;

[0065] (5) After removing the organic matter in step (4), the liquid phase is subjected to MVR evaporation and dehydration at 90-95° C. to obtain a sodium sulfate product.

[0066] In a second aspect, the present invention provides a device for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater, wherein the device is capable of running the method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater described in the first aspect.

[0067] The device comprises an acidolysis reactor, a lithium precipitation device, an impurity removal device, a second pH adjustment device, a catalytic oxidation component and a dehydration device which are sequentially connected along the material conveying direction.

[0068] The device for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater provided in the second aspect of the present invention can continuously and stably operate the method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater provided in the first aspect, and has broad application prospects.

[0069] Preferably, the device further comprises a mother liquor storage device disposed after the dehydration device.

[0070] Preferably, an acidolysis reactor sewage pipe is provided at the bottom of the acidolysis reactor.

[0071] Preferably, the lithium precipitation device comprises a first drug-adding reaction zone, a second drug-adding reaction zone, an inclined tube sedimentation zone and a water outlet zone of the lithium precipitation device in sequence along the material conveying direction.

[0072] Preferably, a lithium sedimentation mud discharge pipe is provided at the bottom of the lithium sedimentation device.

[0073] Preferably, the lithium precipitation device is further provided with a lithium precipitation inclined tube area between the inclined tube sedimentation area and the water outlet area of ​​the lithium precipitation device.

[0074] Preferably, the first drug-adding reaction zone and the second drug-adding reaction zone are each independently provided with a stirrer.

[0075] Preferably, the upper parts of the first drug-adding reaction zone and the second drug-adding reaction zone are each independently provided with a first tail gas extraction device.

[0076] Preferably, the impurity removal device comprises an impurity removal reaction zone, an impurity removal sludge hopper, an impurity removal inclined pipe zone and an impurity removal water outlet zone which are performed in sequence.

[0077] Preferably, a debris removal and mud discharge pipe is provided at the bottom of the debris removal device.

[0078] Preferably, the catalytic oxidation component is a BDD catalytic oxidation reactor.

[0079] Preferably, a sewage outlet is provided at the bottom of the BDD catalytic oxidation reactor, and a second tail gas extraction device is provided at the top.

[0080] Preferably, the water outlet of the BDD catalytic oxidation reactor is provided with a reflux pipeline.

[0081] Preferably, the reflux pipeline is connected to the water inlet of the BDD catalytic oxidation reactor.

[0082] Preferably, the dehydration device is an MVR component.

[0083] Preferably, the MVR assembly comprises a preheater and an MVR evaporator connected in sequence.

[0084] The MVR component also includes a compressor, which can reuse the secondary steam to reduce energy consumption.

[0085] It is worth noting that COD (Chemical Oxygen Demand) in the present invention is chemical oxygen demand, which is the amount of reducing substances that need to be oxidized in the water sample measured by chemical methods. The present invention adopts "HJ / T399-2007 Rapid Digestion Spectrophotometric Method for Determination of Chemical Oxygen Demand of Water Quality" to determine COD in the water sample; TP (Total Phosphorus Water) is total phosphorus, which is the sum of phosphorus in inorganic and organic forms in water. The present invention adopts "HJ / T671-2013 Flow Injection-Ammonium Molybdate Spectrophotometric Method for Determination of Total Phosphorus in Water Quality" to determine TP in the water sample; BDD catalytic oxidation (Boron-Doped Diamond Catalytic Oxidation) refers to catalytic oxidation of germanium-doped diamond electrodes; MVR evaporative dehydration (Mechanical Vapor Recompression) refers to mechanical vapor recompression evaporative dehydration, that is, multi-effect evaporative dehydration.

[0086] Compared with the prior art, the present invention has at least the following beneficial effects:

[0087] (1) The method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater provided by the present invention adopts the "high-temperature acid hydrolysis" process, which can efficiently break the difficult-to-break PF bonds in the electrolyte wastewater, decompose them into orthophosphate and fluoride ions, and then remove them by conventional calcium method, overcoming the industry problem that traditional calcium method, aluminum method, etc. cannot effectively remove phosphorus and fluoride from electrolyte wastewater. And the method of combining electrolyte wastewater with acidic wastewater greatly reduces the amount of acid used, while achieving the purpose of treating waste with waste and saving disposal costs. Under the optimal conditions, the treated effluent has COD≤300mg / L, TP≤7mg / L, and F - ≤13mg / L, Li + ≤50mg / L;

[0088] (2) The method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater provided by the present invention adjusts the pH of the wastewater after high-temperature acid hydrolysis, and adds sodium sulfate to form lithium phosphate precipitation, thereby improving the recovery rate of lithium in the entire battery recovery and having high economic value;

[0089] (3) The method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater provided by the present invention adopts a novel "BDD catalytic oxidation" technology, using the original sulfate in the wastewater as an electrolyte, without the need to add additional reagents. Under certain conditions and electrolysis time, the COD removal rate is as high as 98.0% or more, with stable operation, high removal efficiency and convenient management;

[0090] (4) The method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater provided by the present invention adopts the MVR evaporation process to recover sodium sulfate in the wastewater. The purity of sodium sulfate is ≥99%, which can meet the requirements of Class I first-class products in the product quality standard "GB / T6009-2014 Industrial Wastewater Sodium Sulfate", and is reused in the battery crushing process to reduce the cost of using salt in the battery crushing process; and the mother liquor produced can be reused in the ferrophosphate synthesis process and the battery crushing process, thereby achieving the purpose of full-process recycling of wastewater and zero discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 Schematic diagram of the device for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater provided in Example 1 of the present invention.

[0092] Figure 2 A schematic flow chart of the method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater provided in Example 1 of the present invention.

[0093] In the figure, 1-acidolysis reactor; 2-lithium precipitation device; 3-impurity removal device; 4-second pH adjustment device; 5-catalytic oxidation assembly; 6-dehydration device; 7-mother liquor storage device; 8-acidolysis reactor sewage pipe; 9-first dosing reaction zone; 10-second dosing reaction zone; 11-inclined tube sedimentation zone; 12-lithium precipitation sludge discharge pipe; 13-lithium precipitation inclined tube zone; 14-lithium precipitation device water outlet zone; 15-impurity removal reaction zone; 16-impurity removal sludge hopper; 17-impurity removal sludge discharge pipe; 18-impurity removal inclined tube zone; 19-impurity removal water outlet zone; 20-sewage outlet. DETAILED DESCRIPTION

[0094] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0095] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0096] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0097] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not belong to the main inventive point of the present invention. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0098] Example 1

[0099] This embodiment provides a device for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater, see Figure 1 The device includes an acidolysis reactor 1, a lithium precipitation device 2, an impurity removal device 3, a second pH adjustment device 4, a catalytic oxidation component 5 and a dehydration device 6 which are sequentially connected along the material conveying direction.

[0100] The device further comprises a mother liquid storage device 7 arranged after the dehydration device 6. An acidolysis reactor sewage pipe 8 is arranged at the bottom of the acidolysis reactor 1.

[0101] The lithium sinking device 2 includes a first dosing reaction zone 9, a second dosing reaction zone 10, an inclined tube sedimentation zone 11 and a water outlet zone of the lithium sinking device 2 in sequence along the material conveying direction. A lithium sinking mud discharge pipe 12 is provided at the bottom of the lithium sinking device 2. The lithium sinking device 2 is also provided with a lithium sinking inclined tube zone 13 between the inclined tube sedimentation zone 11 and the water outlet zone 14 of the lithium sinking device. A stirrer is independently provided on the first dosing reaction zone 9 and the second dosing reaction zone 10. The upper parts of the first dosing reaction zone 9 and the second dosing reaction zone 10 are independently provided with a first tail gas extraction device.

[0102] The impurity removal device 3 comprises an impurity removal reaction zone 13, an impurity removal sludge hopper 16, an impurity removal inclined pipe zone 18 and an impurity removal water outlet zone 19. An impurity removal sludge discharge pipe 17 is arranged at the bottom of the impurity removal device 3.

[0103] The catalytic oxidation assembly 5 is a BDD catalytic oxidation reactor. The bottom of the BDD catalytic oxidation reactor is provided with a sewage outlet 20, and the upper part is provided with a second tail gas extraction device. The water outlet of the BDD catalytic oxidation reactor is provided with a reflux pipeline, and the reflux pipeline is connected to the water inlet of the BDD catalytic oxidation reactor.

[0104] The dehydration device 6 is an MVR component. The MVR component includes a preheater and an MVR evaporator connected in sequence.

[0105] This embodiment also provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. See the flow chart for Figure 2 , the method comprises the following steps:

[0106] (1) Battery crushing wastewater (derived from the battery crushing process of waste lithium phosphate batteries) and ferrophosphate synthesis wastewater (derived from the ferrophosphate synthesis process, and the battery powder generated in the battery crushing process is fed into the ferrophosphate synthesis process) are mixed in a volume ratio of 1:2 to obtain mixed wastewater (COD is 19954 mg / L, and the composition includes SO4 2- :150244mg / L,F - :1011mg / L, TP: 3619mg / L, Li + : 3240 mg / L, pH 0.08), and acid hydrolyzed at 90°C for 12 h to obtain waste water after acid hydrolysis, and the tail gas generated by the acid hydrolysis was treated;

[0107] (2) The wastewater after acid hydrolysis in step (1) is first adjusted to pH 12 by adding liquid alkali, and then 3n(PO4 3- ): n(Li + )=1.0, sodium phosphate is added, lithium precipitation reaction is carried out for 40 minutes to recover lithium, and the filtrate is filtered through a filter press to return the filtrate to obtain the first liquid phase, and at the same time, a lithium phosphate product is obtained;

[0108] (3) Mix the first liquid phase and calcium oxide (i.e., calcium-containing compound), the amount of calcium oxide added is 1.0 times the theoretical amount, and perform impurity removal for 2.0 hours to remove PO4 3- 、SO4 2- and F - The generated muddy water is filtered through a filter press, the mud cake is transported out for treatment, and the filtrate is returned to the obtained filtrate, and then the pH is adjusted to pH 8.5 by sulfuric acid to obtain a second liquid phase;

[0109] (4) Step (3) The second liquid phase is treated by BDD catalytic oxidation. The operating voltage of the catalytic oxidation reactor is 4.50 V and the current density is 45 mA / cm 2 , the motor speed is 280r / min, the time is 3.0h, and the liquid phase after removing the organic matter is obtained, and the tail gas generated is treated at the same time;

[0110] (5) After the organic matter is removed in step (4), the liquid phase (mainly sodium sulfate decahydrate) is evaporated and dehydrated by MVR at 92° C. to obtain a sodium sulfate product. The precipitated sodium sulfate is reused in the battery crushing process, and the mother liquor is reused in the iron phosphate synthesis process and the battery crushing process.

[0111] Example 2

[0112] This embodiment adopts the device provided in Example 1 to provide a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater, the method comprising the following steps:

[0113] (1) Battery crushing wastewater (derived from the battery crushing process of waste lithium phosphate batteries) and ferrophosphorus synthesis wastewater (derived from the ferrophosphate synthesis process, and the battery powder generated in the battery crushing process is fed into the ferrophosphate synthesis process) are mixed in a volume ratio of 1:5 to obtain mixed wastewater (COD of 11630 mg / L, including SO4 2- :140279mg / L,F - :1490mg / L, TP: 1415mg / L, Li + : 560 mg / L, pH 0.00, 95°C for 14 h to obtain acid hydrolysis wastewater, and the tail gas generated by the acid hydrolysis treatment was treated;

[0114] (2) The wastewater after acid hydrolysis in step (1) is first adjusted to pH 13 by adding liquid alkali, and then 3n(PO4 3- ): n(Li + )=1.5, sodium phosphate is added, lithium precipitation reaction is carried out for 30 minutes to recover lithium, and the filtrate is filtered through a filter press to return the filtrate to obtain the first liquid phase, and a lithium phosphate product is obtained at the same time;

[0115] (3) Mix the first liquid phase and calcium hydroxide (i.e., calcium-containing compound), the amount of calcium hydroxide added is 1.5 times the theoretical amount, and perform impurity removal for 3.0 hours to remove PO4 3- 、SO4 2- and F - The generated muddy water is filtered through a filter press, the mud cake is transported out for treatment, and the filtrate is returned to the obtained filtrate, and then the pH is adjusted to pH 7 by sulfuric acid to obtain a second liquid phase;

[0116] (4) Step (3) The second liquid phase is treated by BDD catalytic oxidation. The operating voltage of the catalytic oxidation reactor is 5.10 V and the current density is 40 mA / cm 2 , the motor speed is 250r / min, the time is 2.0h, and the liquid phase after removing the organic matter is obtained, and the tail gas generated is treated at the same time;

[0117] (5) After the organic matter is removed in step (4), the liquid phase (mainly sodium sulfate decahydrate) is evaporated and dehydrated by MVR at 95° C. to obtain a sodium sulfate product. The precipitated sodium sulfate is reused in the battery crushing process, and the mother liquor is reused in the iron phosphate synthesis process and the battery crushing process.

[0118] Example 3

[0119] This embodiment adopts the device provided in Example 1 to provide a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater, the method comprising the following steps:

[0120] (1) Battery crushing wastewater (derived from the battery crushing process of waste lithium phosphate batteries) and ferrophosphate synthesis wastewater (derived from the ferrophosphate synthesis process, and the battery powder generated in the battery crushing process is fed into the ferrophosphate synthesis process) are mixed in a volume ratio of 1:1 to obtain mixed wastewater (COD is 29110 mg / L, and the composition includes SO4 2- : 159833mg / L, F-: 1490mg / L, TP: 4990mg / L, Li + : 4850 mg / L, pH 0.20), and subjected to acid hydrolysis at 85°C for 9 hours to obtain waste water after acid hydrolysis, and the tail gas generated by the acid hydrolysis was subjected to tail gas treatment;

[0121] (2) The wastewater after acid hydrolysis in step (1) is first adjusted to pH 11 by adding liquid alkali, and then 3n(PO4 3- ): n(Li + )=0.9, sodium phosphate is added, lithium precipitation reaction is carried out for 60 minutes to recover lithium, and the filtrate is filtered through a filter press to return the filtrate to obtain the first liquid phase, and a lithium phosphate product is obtained at the same time;

[0122] (3) Mix the first liquid phase and calcium oxide (i.e., calcium-containing compound), the amount of calcium oxide added is 0.9 times the theoretical amount, and perform impurity removal for 1.5 hours to remove PO4 3- 、SO4 2- and F - The generated muddy water is filtered through a filter press, the mud cake is transported out for treatment, and the filtrate is returned to the obtained filtrate, and then the pH is adjusted to pH 9 by sulfuric acid to obtain a second liquid phase;

[0123] (4) Step (3) The second liquid phase is treated by BDD catalytic oxidation. The operating voltage of the catalytic oxidation reactor is 4.00 V and the current density is 50 mA / cm 2 , the motor speed is 300r / min, the time is 4.0h, and the liquid phase after the organic matter is removed is obtained, and the tail gas generated is treated at the same time;

[0124] (5) After the organic matter is removed in step (4), the liquid phase (mainly sodium sulfate decahydrate) is evaporated and dehydrated by MVR at 90° C. to obtain a sodium sulfate product. The precipitated sodium sulfate is recycled to the battery crushing process, and the mother liquor is recycled to the iron phosphate synthesis process and the battery crushing process.

[0125] Example 4

[0126] This embodiment provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. Except that the pH value of the mixed wastewater is 0.3, the rest of the method is the same as that of Example 1, and will not be repeated here.

[0127] Example 5

[0128] This embodiment provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. The method is the same as that in Example 1 except that the temperature of the acid hydrolysis treatment is 80°C, and will not be described again.

[0129] Example 6

[0130] This embodiment provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. The method removes 3n(PO4 3- ): n(Li + )=0.8 and sodium phosphate was added, and the rest was the same as in Example 1, which will not be described again.

[0131] Example 7

[0132] This embodiment provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. Except that the amount of calcium oxide added in step (3) is 0.7 times the theoretical amount, the rest is the same as Example 1 and will not be repeated here.

[0133] Example 8

[0134] This embodiment provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. Except for the second adjustment of pH to pH 6.0 in step (3), the rest of the method is the same as that in Example 1 and will not be repeated here.

[0135] Example 9

[0136] This embodiment provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. Except for the second adjustment of pH to pH 10.0 in step (3), the rest of the method is the same as that in Example 1 and will not be repeated here.

[0137] Example 10

[0138] This embodiment provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. Except for the time in step (4) being 1.0 h, the rest of the method is the same as that in Example 1 and will not be repeated here.

[0139] Comparative Example 1

[0140] This comparative example provides a method for treating battery crushing wastewater. Except for directly subjecting the battery crushing wastewater to acid hydrolysis treatment, the rest of the method is the same as Example 1, which will not be repeated here.

[0141] Comparative Example 2

[0142] This comparative example provides a method for treating ferrophosphorus synthesis wastewater. Except for directly subjecting the ferrophosphorus synthesis wastewater to acid hydrolysis treatment, the rest of the method is the same as Example 1, which will not be repeated here.

[0143] Comparative Example 3

[0144] This comparative example provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. Except for performing acid hydrolysis treatment at room temperature (25°C), the rest of the method is the same as Example 1, which will not be repeated here.

[0145] Comparative Example 4

[0146] This comparative example provides a method for the combined treatment of battery crushing wastewater and ferrophosphorus synthesis wastewater. The method is the same as Example 1 except that step (3) is omitted and step (4) of catalytic oxidation treatment is directly performed, and the details are not repeated here.

[0147] Comparative Example 5

[0148] This comparative example provides a method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater. The method is the same as Example 1 except that sodium phosphate is replaced by sodium carbonate in step (2), and the rest is not repeated here.

[0149] Test method:

[0150] The COD in water samples was determined using the "HJ / T399-2007 Rapid Digestion Spectrophotometric Method for Determination of Chemical Oxygen Demand in Water";

[0151] The TP in water samples was determined using the "HJ / T671-2013 Determination of total phosphorus in water quality - flow injection-ammonium molybdate spectrophotometry";

[0152] The F content in water samples was determined by GB / T21057-2007 General method for determination of fluorine content in inorganic chemical products - ion selective electrode method. - ;

[0153] Determination of SO4 in water samples using GB / T13025.8-2012 General test method for salt industry - Determination of sulfate 2- ;

[0154] The Li in water samples was determined by using the "GB / T30902-2014 Determination of impurity elements in inorganic chemical products - Inductively coupled plasma optical emission spectrometry (ICP-OES)" + ;

[0155] Sodium sulfate was determined using GB / T6009-2014 Industrial Anhydrous Sodium Sulfate.

[0156] The test results of the above embodiments and comparative examples are shown in Table 1.

[0157] Table 1

[0158]

[0159]

[0160] From Table 1 we can see that:

[0161] 1. It can be seen from Examples 1 to 3 that after the battery crushing wastewater and the ferrophosphorus synthesis wastewater are mixed and treated with acid hydrolysis, lithium precipitation, impurity removal and catalytic oxidation, COD≤300mg / L, TP≤7mg / L, F - ≤13mg / L, Li + ≤50mg / L, and after evaporation dehydration treatment, the purity of sodium sulfate is ≥99%, which can meet the requirements of Class I first-class products in the product quality standard of "GB / T6009-2014 Sodium Sulfate for Industrial Wastewater".

[0162] 2. Comparing Example 1 with Example 4, the pH of the acid hydrolysis treatment was increased, and the TP concentration after impurity removal treatment increased from 4.9 mg / L to 121.5 mg / L. - The concentration increased from 10.2 mg / L to 37.4 mg / L, indicating that the present invention needs to provide a sufficient hydrogen ion concentration so that the active hydrogen migrates faster than the lithium ions and combines with the fluoride ions first, thereby promoting the reaction and further improving the wastewater treatment effect.

[0163] 3. Comparing Example 1 with Example 5, the temperature of the acid hydrolysis treatment was lowered. Under the same conditions, the TP concentration increased from 4.9 mg / L to 309.8 mg / L. - The concentration increased from 10.2 mg / L to 41.8 mg / L, which shows that the present invention controls the temperature of the acid hydrolysis treatment within a reasonable range and has a better wastewater treatment effect.

[0164] 4. Comparing Example 1 with Example 6 to Example 7, in Example 6, the dosage of sodium phosphate was reduced, and Li + The concentration increased from 32.4 mg / L to 85.5 mg / L. In Example 7, the dosage of calcium oxide was reduced, and the TP concentration increased from 4.9 mg / L to 1191.5 mg / L. - The concentration increased from 10.2 mg / L to 332.8 mg / L, which shows that the present invention controls the dosage of the reagent to be greater than or equal to 0.9 times the theoretical value, which can better precipitate lithium and remove impurities.

[0165] 5. By comparing Example 1 with Examples 8 to 10, it can be seen that the present invention controls the catalytic oxidation pH within the range of 7 to 9, and the reaction time is not less than 2 hours, COD can be fully decomposed, and the removal of organic matter can be better achieved.

[0166] 6. By comparing Example 1 with Comparative Example 1 and Comparative Example 2, it can be seen that when treating the battery crushing wastewater alone, the wastewater contains PF bonds that are difficult to break, TP and F - There is no obvious removal effect. When treating phosphorus-iron synthesis wastewater alone, since phosphorus and fluorine in the wastewater are inorganic phosphorus and inorganic fluorine, calcium oxide is added to remove impurities, TP and F - The levels were reduced to 1.9mg / L and 1.2mg / L respectively, but the coordinated treatment of battery crushing wastewater and ferrophosphorus synthesis wastewater could not be achieved.

[0167] 7. Comparison of Example 1 and Comparative Examples 3 to 4 shows that in Comparative Example 3, acid hydrolysis was performed at room temperature, TP and F - The concentration did not change, indicating that under acid hydrolysis at room temperature, TP and F - No obvious removal effect. In comparative example 4, the impurity removal and pH adjustment in step (3) were not performed, and catalytic oxidation was directly performed. The COD of the wastewater was affected by the pH and only dropped to 929.4 mg / L. TP and F - 、SO4 2- No obvious removal effect.

[0168] 8. Comparing Example 1 with Comparative Example 5, in Comparative Example 5, sodium carbonate was used instead of sodium phosphate, and the efficiency of lithium precipitation decreased from 99% to 75%, indicating that sodium phosphate should be selected to improve the lithium precipitation efficiency of the system.

[0169] In summary, the battery crushing wastewater should be treated under acidic conditions after mixing with the iron phosphate synthesis wastewater, and acid hydrolysis treatment should be carried out at high temperature, and calcium impurity removal treatment should be carried out to effectively remove TP and F- in the wastewater. However, the single treatment of battery crushing wastewater cannot achieve the purpose of wastewater removal and reuse effect, and the single treatment of iron phosphate synthesis wastewater cannot achieve the purpose of treating waste with waste. For wastewater mixed in different proportions, the higher the acid hydrolysis temperature, the stronger the acidity, the more sodium phosphate added, the more calcium added, and the longer the catalytic oxidation time, the better the effect, but the cost increases accordingly. Considering the most economical situation, the range listed in the present invention is the optimal treatment condition.

[0170] The present invention illustrates the detailed features of the present invention through the above embodiments, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvement to the present invention, equivalent replacement of the technical features selected by the present invention, addition of auxiliary technical features, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater, characterized in that: The method comprises: (1) mixing battery crushing wastewater and ferrophosphorus synthesis wastewater, and subjecting the obtained mixed wastewater to acid hydrolysis treatment to obtain acid-hydrolyzed wastewater; (2) The wastewater after acid hydrolysis in step (1) is subjected to a first pH adjustment, mixed with a phosphorus source, and lithium is recovered to obtain a first liquid phase; (3) Step (2) wherein the first liquid phase is subjected to sequential impurity removal and second pH adjustment to obtain a second liquid phase; (4) The second liquid phase in step (3) is subjected to catalytic oxidation treatment to obtain a liquid phase after organic matter is removed; (5) After removing the organic matter in step (4), the liquid phase is dehydrated to obtain a sodium sulfate product.

2. The method according to claim 1, characterized in that The pH of the battery crushing wastewater in step (1) is 2 to 4; Preferably, the COD of the battery crushing wastewater is 20000-60000 mg / L; Preferably, the composition of the battery crushing wastewater includes SO4 2- :80~100g / L,F - :2000~3000mg / L,TP:5000~10000mg / L and Li + :5000~10000mg / L. Preferably, the composition of the ferric phosphate synthesis wastewater includes H + :1200~1400mg / L,SO4 2- :140~180g / L、F - : 2~10mg / L and TP: 200~4000mg / L; Preferably, the COD of the iron phosphate synthesis wastewater is 20 to 40 mg / L; Preferably, the COD of the mixed wastewater is 10000-30000 mg / L; Preferably, the composition of the mixed wastewater includes SO4 2- :140~160g / L,F - :500~1500mg / L, TP: 1400~5000mg / L, Li + : 1200~5000mg / L; Preferably, the pH of the mixed wastewater is 0 to 0.

20.

3. The method according to claim 1 or 2, characterized in that: The volume ratio of the battery crushing wastewater to the acidic wastewater in step (1) is 1:1 to 1:5; Preferably, the temperature of the acid hydrolysis treatment is 85-95°C; Preferably, the acid hydrolysis treatment time is 9 to 14 hours.

4. The method according to any one of claims 1 to 3, characterized in that: In step (2), the first step of adjusting the pH to a pH of 11 to 13; Preferably, the phosphorus source is sodium phosphate; Preferably, the amount of the phosphorus source added is 3n(PO4 3- ): n(Li + )=0.9~1.5; Preferably, the reaction time for recovering lithium is 30 to 60 minutes.

5. The method according to any one of claims 1 to 4, characterized in that: The impurity removal in step (3) includes: mixing the first liquid phase and the calcium source to perform an impurity removal process; Preferably, the calcium source is a calcium-containing compound, preferably calcium oxide and / or calcium hydroxide; Preferably, the amount of calcium source added is 0.9 to 1.5 times the theoretical amount; Preferably, the reaction time in the impurity removal process is 1.5 to 3.0 h; Preferably, PO4 is removed during the impurity removal process. 3- 、SO4 2- and F - ; Preferably, in step (3), the second step of adjusting the pH is to a pH of 7 to 9.

6. The method according to any one of claims 1 to 5, characterized in that: The operating voltage of the catalytic oxidation reactor in the catalytic oxidation treatment in step (4) is 4.00 to 5.10 V; Preferably, the current density of the catalytic oxidation reactor in the catalytic oxidation treatment is 40-50 mA / cm 2 ; Preferably, the motor speed of the catalytic oxidation reactor in the catalytic oxidation treatment is 250-300 r / min; Preferably, the catalytic oxidation treatment time is 2.0 to 4.0 hours.

7. The method according to any one of claims 1 to 6, characterized in that: The dehydration method in step (5) is evaporative dehydration; Preferably, the evaporative dehydration method is MVR evaporative dehydration; Preferably, the temperature of the MVR evaporation and dehydration is 90-95°C.

8. A device for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater, characterized in that: The device is capable of operating the method for jointly treating battery crushing wastewater and ferrophosphorus synthesis wastewater as described in any one of claims 1 to 7; The device comprises an acidolysis reactor (1), a lithium precipitation device (2), an impurity removal device (3), a second pH adjustment device (4), a catalytic oxidation component (5) and a dehydration device (6) which are sequentially connected along a material conveying direction.

9. The device according to claim 8, characterized in that The lithium precipitation device (2) comprises, in sequence along the material conveying direction, a first drug addition reaction zone (9), a second drug addition reaction zone (10), an inclined tube sedimentation zone (11) and a lithium precipitation device water outlet zone (14); Preferably, the first drug addition reaction zone (9) and the second drug addition reaction zone (10) are each independently provided with a stirrer; Preferably, the upper parts of the first drug-adding reaction zone (9) and the second drug-adding reaction zone (10) are each independently provided with a first tail gas extraction device.

10. The device according to claim 8 or 9, characterized in that The catalytic oxidation component (5) is a BDD catalytic oxidation reactor; Preferably, the BDD catalytic oxidation reactor is provided with a sewage outlet (20) at the bottom and a second tail gas extraction device at the top; Preferably, the water outlet of the BDD catalytic oxidation reactor is provided with a reflux pipeline; Preferably, the dehydration device (6) is an MVR component; the MVR component comprises a preheater and an MVR evaporator connected in sequence.

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