A method for treating hydrometallurgical extraction wastewater

Abstract

This invention provides a method for treating hydrometallurgical extraction wastewater, comprising the following steps: (1) mixing the extraction wastewater and a calcium source, stirring once, and then performing solid-liquid separation to obtain a first filtrate; (2) mixing the first filtrate and carbonate, stirring twice, and then filtering to remove calcium to obtain a second filtrate; (3) mixing the second filtrate and a defluorinating agent, and then sequentially performing acid-base adjustment, stirring three times, and solid-liquid separation to obtain a third filtrate; (4) mixing the third filtrate and sodium hypochlorite solution, stirring four times, and then obtaining treated purified water. The treatment method provided by this invention can effectively reduce fluoride ions and oil content in wastewater, meeting wastewater discharge standards. Furthermore, the treatment method is low-cost, low-energy-consumption, pollution-free, and simple to operate, and has significant application prospects.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for treating wastewater from hydrometallurgical extraction. Background Technology

[0002] Cobalt, nickel, and manganese mineral resources are important raw materials for the production of NCM ternary precursors. The purification of cobalt, nickel, and manganese is generally achieved through a leaching-extraction process, with the organic phase undergoing acid washing, water washing, and saponification to achieve the recycling of the extractant – a common process method. The extraction wastewater generated by this process often contains fluoride ions and oil, making direct discharge impossible. Currently, methods for removing fluoride ions from wastewater mainly include defluorination with fluoridating agents, resin adsorption, or lime precipitation; methods for removing oil mainly include activated carbon adsorption or the use of oil separators.

[0003] However, when the fluoride concentration in wastewater is high, defluorinating agents used for deep defluorination often fail to achieve the desired level of defluorination and are economically inefficient. Extraction wastewater is characterized by high oil and salt content and high hardness, which affects resin adsorption performance and causes caking; resin regeneration also suffers from low economic efficiency. Chemical precipitation methods are limited by the solubility of the precipitate, resulting in a defluorination limit, typically around 20 mg / L.

[0004] CN 111646591A discloses a method for treating semiconductor fluoride-containing wastewater. The method includes the following steps: adding calcium salt and conditioned sludge to the wastewater to be treated and stirring to obtain a reaction solution; adding flocculant to the reaction solution and then separating the sludge and water to obtain sludge containing calcium fluoride and treated clean water. CN117509936A discloses a method for removing fluoride from high-concentration fluoride-containing wastewater. The method includes the following steps: (1) adding water-soluble calcium-containing compounds to the fluoride-containing wastewater, then adding composite flocculant and coagulant aid, reacting and removing the precipitate; (2) adjusting the pH of the fluoride-containing wastewater treated in step (1) to 7-10 and then entering the electrocoagulation unit for deep treatment; (3) removing the precipitate from the electrocoagulation unit's permeate to obtain the final permeate.

[0005] The aforementioned patents all disclose how to remove fluoride from wastewater, but do not disclose how to remove oil from fluoride-containing wastewater.

[0006] Therefore, providing a process that can simultaneously treat fluoride ions and oil in wastewater has significant application prospects. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for treating hydrometallurgical extraction wastewater. This method achieves low-cost, deep defluorination and oil removal from hydrometallurgical extraction wastewater through step-by-step treatment. Furthermore, the method is simple to operate, uses simple equipment, consumes little energy, and is pollution-free, thus possessing significant application prospects.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This invention provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0010] (1) Mix the extraction wastewater and calcium source, stir once, and then perform solid-liquid separation to obtain the first filtrate;

[0011] (2) Mix the first filtrate and carbonate, stir twice, and then filter to remove calcium to obtain the second filtrate;

[0012] (3) After mixing the second filtrate and the defluorinating agent, acid-base adjustment, stirring three times and solid-liquid separation are performed in sequence to obtain the third filtrate;

[0013] (4) Mix the third filtrate and sodium hypochlorite solution, and stir four times to obtain the treated water.

[0014] In this invention, the preliminary treatment of fluoride ions and oil in the extraction wastewater is achieved by mixing calcium sources, then the calcium ions in the filtrate are deeply treated by mixing carbonates, then the fluoride ions in the wastewater are deeply treated by mixing defluorinating agents, and finally the oil in the wastewater is deeply treated by sodium hypochlorite.

[0015] This invention can efficiently reduce fluoride ions and oil content in extraction wastewater through stepwise treatment to meet emission standards. The treatment method is simple to operate, uses simple equipment, has low energy consumption, and is pollution-free, and has important application prospects.

[0016] In addition, the extraction wastewater described in this invention is a mixed wastewater of extract, washing acid, and washing water generated after extraction and enrichment of nickel sulfate and lithium carbonate; this extraction wastewater contains high concentrations of fluoride ions and oil.

[0017] The discharge standards for the extraction wastewater described in this invention are: oil content ≤ 5 mg / L, calcium ion content ≤ 5 mg / L, and fluoride ion content ≤ 5 mg / L.

[0018] As a preferred technical solution of the present invention, the fluoride ion content in the extraction wastewater in step (1) is ≥150mg / L, for example, it can be 150mg / L, 170mg / L, 190mg / L, 210mg / L, 230mg / L, 250mg / L or 270mg / L, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the oil content in the extraction wastewater in step (1) is ≥80mg / L, for example, it can be 80mg / L, 90mg / L, 100mg / L, 110mg / L, 120mg / L or 130mg / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] As a preferred technical solution of the present invention, the calcium source in step (1) includes any one or at least two of calcium hydroxide, calcium oxide or calcium chloride. Typical but non-limiting combinations include: a combination of calcium hydroxide and calcium oxide, a combination of calcium hydroxide and calcium chloride, a combination of calcium oxide and calcium chloride, or a combination of calcium hydroxide, calcium oxide and calcium chloride.

[0021] Preferably, the molar ratio of fluoride ions in the extraction wastewater and calcium ions in the calcium source in step (1) is 1:8 to 12, for example, it can be 1:8, 1:8.8, 1:9.6, 1:10.4, 1:11.2 or 1:12, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] In this invention, the calcium source is used to combine with fluoride ions to produce calcium fluoride through chemical precipitation, thus achieving the initial removal of fluoride ions. If the amount added is too high, it will result in a high calcium content in the first filtrate, a high amount of carbonate added subsequently, a high salt content in the final wastewater, and low economic benefits. Conversely, if the amount added is too low, it will result in a high fluoride content in the first filtrate, a high amount of defluorinating agent added subsequently, and low economic benefits.

[0023] As a preferred technical solution of the present invention, the stirring time in step (1) is 30~120min, for example, it can be 30min, 50min, 70min, 90min, 110min or 120min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] As a preferred embodiment of the present invention, the carbonate in step (2) includes sodium carbonate.

[0025] Preferably, the Ca in the first filtrate 2+ CO3 in carbonates 2-The molar ratio is 1:2 to 2.5, for example, it can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4 or 1:2.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] As a preferred embodiment of the present invention, the calculation formula for the amount w of the defluorinating agent added in step (3) is as follows:

[0027] w=c(F - )×V×m×n

[0028] Wherein, c(F) - ) represents F in the second filtrate - Concentration, V is the volume of the second filtrate, m is the magnification factor, and n is the theoretical excess coefficient of the defluorinating agent.

[0029] Preferably, the value of m is in the range of 3 to 5, for example, 3, 4 or 5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In this invention, the value of the magnification factor m is further determined according to the type of defluorinating agent selected.

[0031] As a preferred technical solution of the present invention, the reagents used for acid-base adjustment in step (3) include any one or at least two of hydrochloric acid, sulfuric acid or nitric acid. Typical but non-limiting combinations include: a combination of hydrochloric acid and sulfuric acid, a combination of hydrochloric acid and nitric acid, a combination of sulfuric acid and nitric acid, or a combination of hydrochloric acid, sulfuric acid and nitric acid.

[0032] Preferably, the endpoint of the acid-base adjustment in step (3) is a pH value of 7 to 8, for example, it can be 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 or 8, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] In this invention, the purpose of acid-base adjustment in step (3) is to maximize the sedimentation efficiency of the defluorinating agent; if the pH value is too low, the removal of fluoride ions will be incomplete, and conversely, if the pH value is too high, the removal of fluoride ions will be incomplete.

[0034] As a preferred technical solution of the present invention, the stirring time for the three times in step (3) is 8~12min, for example, it can be 8min, 9min, 10min, 11min or 12min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] As a preferred technical solution of the present invention, the amount of sodium hypochlorite solution added in step (4) is 2~15 mL / L, for example, it can be 2 mL / L, 5 mL / L, 8 mL / L, 10 mL / L, 12 mL / L or 15 mL / L, but is not limited to the listed values. Other values ​​not listed in the value range are also applicable.

[0036] Preferably, the concentration of the sodium hypochlorite solution in step (4) is 10~15wt%, for example, it can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the time for the four stirrings in step (4) is 2 to 4.5 hours, for example, it can be 2 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours, 4 hours, 4.1 hours, 4.2 hours, 4.3 hours, 4.4 hours or 4.5 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] As a preferred embodiment of the present invention, the method for treating hydrometallurgical extraction wastewater provided by the present invention includes the following steps:

[0039] (1) Mix the extraction wastewater and calcium source, stir for 30-120 min, and then perform solid-liquid separation to obtain the first filtrate;

[0040] The fluoride ion content in the extraction wastewater is ≥150mg / L, and the oil content is ≥80mg / L.

[0041] The molar ratio of fluoride ions in the extraction wastewater to calcium ions in the calcium source is 1:8~12;

[0042] (2) Mix the first filtrate and sodium carbonate, stir twice, and then filter to remove calcium to obtain the second filtrate;

[0043] Among them, Ca in the first filtrate 2+ CO3 in carbonates 2- The molar ratio is 1:2~2.5;

[0044] (3) After mixing the second filtrate and the defluorinating agent, the pH value is adjusted to 7-8, stirred three times for 8-12 minutes, and then separated into solid and liquid to obtain the third filtrate;

[0045] Wherein, the amount of defluorinating agent added w = c(F - )×V×m×n,,c(F - ) represents F in the second filtrate - Concentration, V is the volume of the second filtrate, m is the magnification factor, and n is the theoretical excess coefficient of the defluorinating agent;

[0046] (4) Mix the third filtrate with a sodium hypochlorite solution with a concentration of 10~15wt%, stir four times for 2~4.5h to obtain the treated water.

[0047] It is worth noting that the present invention is not limited to the solid-liquid separation method described above, as long as the separation of solids and liquids in the reaction solution can be achieved.

[0048] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The treatment method provided by the present invention achieves the purpose of deep defluorination and oil removal of low-cost extraction wastewater through a step-by-step treatment method of "preliminary oil and fluoride removal - calcium removal - deep defluorination - deep oil removal", which has important application prospects;

[0051] (2) The processing method provided by the present invention has the advantages of simple operation, simple equipment, low energy consumption and no pollution;

[0052] (3) The treatment method provided by the present invention achieves the standard discharge of extraction wastewater and solves the problems of high oil and fluoride content in extraction wastewater and the need to use high-cost equipment. Attached Figure Description

[0053] Figure 1 This is a process flow diagram of the method for treating hydrometallurgical extraction wastewater provided in Embodiment 1 of the present invention. Detailed Implementation

[0054] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0055] The defluorinating agent used in the following examples and comparative examples is GMS-F3 defluorinating agent produced by Shandong Huanrui Ecological Technology Co., Ltd., with a theoretical excess coefficient of 50.

[0056] Example 1

[0057] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, such as... Figure 1 As shown, the processing method includes the following steps:

[0058] (1) Mix the extraction wastewater and calcium hydroxide slurry with a concentration of 25wt%, stir for 60 minutes, and then perform solid-liquid separation to obtain the first filtrate;

[0059] The fluoride ion content in the extraction wastewater was 183.22 mg / L, and the oil content was 89.57 mg / L.

[0060] The molar ratio of fluoride ions in the extraction wastewater to calcium ions in the calcium source is 1:8.

[0061] Analysis of the first filtrate showed that the precipitation rate of F was 91.77%, the F content was 15.07 mg / L, the Ca content was 273.5 mg / L, and the oil content was 66.79 mg / L.

[0062] (2) Mix the first filtrate and sodium carbonate, stir for 1 hour, and then filter to remove calcium to obtain the second filtrate;

[0063] Among them, Ca in the first filtrate 2+ CO3 in carbonates 2- The molar ratio is 1:2;

[0064] After testing and analysis of the second filtrate, it was found that the precipitation rate of Ca was 99.41%, the F ion content was 15.07 mg / L, the Ca ion content was 3.4 mg / L, and the oil content was 66.79 mg / L.

[0065] (3) After mixing the second filtrate and the defluorinating agent, mix hydrochloric acid to adjust the pH to 7.5, then stir for 10 minutes three times and separate the solid and liquid to obtain the third filtrate;

[0066] Wherein, the amount of defluorinating agent added w = c(F - )×V×150,c(F - ) represents F in the second filtrate - Concentration, V is the volume of the second filtrate;

[0067] After testing and analysis of the third filtrate, it was found that the precipitation rate of F was 81.5%, the F ion content was 2.78 mg / L, the Ca ion content was 3.4 mg / L, and the oil content was 66.79 mg / L.

[0068] (4) Mix the third filtrate with a sodium hypochlorite solution with a concentration of 10 wt%, stir four times for 4 hours, and obtain the treated water;

[0069] The amount of sodium hypochlorite solution added is 10 mL / L.

[0070] Example 2

[0071] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, such as... Figure 1 As shown, the processing method includes the following steps:

[0072] (1) Mix the extraction wastewater and calcium oxide slurry with a concentration of 25wt%, stir for 50 minutes, and then perform solid-liquid separation to obtain the first filtrate;

[0073] The fluoride ion content in the extraction wastewater was 154.92 mg / L, and the oil content was 94.23 mg / L.

[0074] The molar ratio of fluoride ions in the extraction wastewater to calcium ions in the calcium source is 1:12.

[0075] Analysis of the first filtrate revealed that the precipitation rate of F was 92.3%, the F ion content was 12.45 mg / L, the Ca ion content was 892.5 mg / L, and the oil content was 41.96 mg / L.

[0076] (2) Mix the first filtrate and sodium carbonate, stir twice, and then filter to remove calcium to obtain the second filtrate;

[0077] Among them, Ca in the first filtrate 2+ CO3 in carbonates 2- The molar ratio is 1:2.5;

[0078] Analysis of the second filtrate revealed that the precipitation rate of Ca was 99.41%; the F ion content was 12.45 mg / L; the Ca ion content was 2.21 mg / L; and the oil content was 41.96 mg / L.

[0079] (3) After mixing the second filtrate and the defluorinating agent, the pH value was adjusted to 7.5, stirred for 8 minutes three times, and then the solid and liquid were separated to obtain the third filtrate.

[0080] Wherein, the amount of defluorinating agent added w = c(F - )×V×150,c(F - ) represents F in the second filtrate - Concentration, V is the volume of the second filtrate;

[0081] Analysis of the third filtrate revealed that the precipitation rate of F was 81.5%; the F ion content was 2.79 mg / L; the Ca ion content was 2.21 mg / L; and the oil content was 41.96 mg / L.

[0082] (4) Mix the third filtrate with a sodium hypochlorite solution with a concentration of 12wt%, stir four times for 4.5h, and obtain the treated water;

[0083] The amount of sodium hypochlorite solution added is 10 mL / L.

[0084] Example 3

[0085] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, such as... Figure 1 As shown, the processing method includes the following steps:

[0086] (1) Mix the extraction wastewater and calcium chloride slurry with a concentration of 25wt%, stir for 70 minutes, and then perform solid-liquid separation to obtain the first filtrate;

[0087] The fluoride ion content in the extraction wastewater was 297.98 mg / L, and the oil content was 93.67 mg / L.

[0088] The molar ratio of fluoride ions in the extraction wastewater to calcium ions in the calcium source is 1:10.

[0089] (2) Mix the first filtrate and sodium carbonate, stir twice, and then filter to remove calcium to obtain the second filtrate;

[0090] Among them, Ca in the first filtrate 2+ CO3 in carbonates 2- The molar ratio is 1:2.25;

[0091] (3) After mixing the second filtrate and the defluorinating agent, the pH value was adjusted to 8, stirred for 12 minutes three times, and then the solid and liquid were separated to obtain the third filtrate.

[0092] Wherein, the amount of defluorinating agent added w = c(F - )×V×150,c(F - ) represents F in the second filtrate - Concentration, V is the volume of the second filtrate;

[0093] (4) Mix the third filtrate with a sodium hypochlorite solution with a concentration of 15 wt%, stir four times for 2.5 h, and obtain the treated water;

[0094] The amount of sodium hypochlorite solution added is 8 mL / L.

[0095] Example 4

[0096] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0097] In this embodiment, the molar ratio of fluoride ions in the extraction wastewater and calcium ions in the calcium source in step (1) is adjusted to 1:5.

[0098] Example 5

[0099] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0100] In this embodiment, the molar ratio of fluoride ions in the extraction wastewater and calcium ions in the calcium source in step (1) is adjusted to 1:15.

[0101] Example 6

[0102] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0103] This embodiment will address the Ca in the first filtrate in step (2). 2+ CO3 in carbonates 2- The molar ratio is adjusted to 1.8:1.

[0104] Example 7

[0105] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0106] This embodiment will address the Ca in the first filtrate in step (2). 2+ CO3 in carbonates 2- The molar ratio is adjusted to 3.0:1.

[0107] Example 8

[0108] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0109] In this embodiment, the endpoint of acid-base adjustment in step (3) is adjusted to a pH value of 6.5.

[0110] Example 9

[0111] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0112] In this embodiment, the endpoint of acid-base adjustment in step (3) is adjusted to a pH value of 8.5.

[0113] Example 10

[0114] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0115] In this embodiment, the amount of sodium hypochlorite solution added in step (3) is adjusted to 1 mL / L.

[0116] Example 11

[0117] This embodiment provides a method for treating wastewater from hydrometallurgical extraction, the method comprising the following steps:

[0118] In this embodiment, the amount of sodium hypochlorite solution added in step (3) is adjusted to 18 mL / L.

[0119] Comparative Example 1

[0120] This comparative example provides a method for treating hydrometallurgical extraction wastewater, the method comprising the following steps:

[0121] Steps (1) and (2) are omitted in this comparative example.

[0122] Comparative Example 2

[0123] This comparative example provides a method for treating hydrometallurgical extraction wastewater, the method comprising the following steps:

[0124] In this comparative example, the sodium hypochlorite solution described in step (4) is adjusted to a potassium permanganate solution of equal concentration.

[0125] Comparative Example 3

[0126] This comparative example provides a method for treating hydrometallurgical extraction wastewater, the method comprising the following steps:

[0127] This comparative example adjusts the mixing order of the defluorinating agent and sodium hypochlorite, that is, steps (3) and (4) of the treatment method are adjusted as follows:

[0128] (3) Mix the second filtrate with a 10 wt% sodium hypochlorite solution, stir for 4 h and then perform solid-liquid separation to obtain the third filtrate; the amount of sodium hypochlorite solution added is 10 mL / L;

[0129] (4) Mix the third filtrate and the defluorinating agent, then mix with hydrochloric acid to adjust the pH to 7.5, then stir for 10 minutes three times and separate the solid and liquid to obtain the treated water.

[0130] The treated water provided in the above embodiments and comparative examples was tested and analyzed. The concentrations of F ions, calcium ions, and oil content in the water were detected, and the results are shown in Table 1.

[0131] Table 1

[0132]

[0133] According to Table 1, the following points can be observed:

[0134] (1) Comprehensive analysis of Examples 1-3 shows that the treatment method provided by the present invention can effectively reduce fluoride ions and oil in wastewater and meet the wastewater discharge standards;

[0135] In addition, the processing method is low in cost, low in energy consumption, pollution-free and simple to operate, and has important application prospects;

[0136] (2) Comprehensive analysis of Examples 1 and 4-5 shows that the amount of calcium source added will affect the initial defluorination and oil removal effect of the extraction wastewater. When the amount of calcium source added is too low, it will lead to a large amount of defluorinating agent added and a high concentration of fluoride ions. Conversely, when the amount of calcium source added is too high, a large amount of sodium carbonate needs to be added in order to make the treated water meet the discharge standards, which will lead to an increase in treatment costs.

[0137] It is worth noting that in Example 5, when the amount of calcium source added in step (1) is too high, in order to make the calcium ion content in the treated water meet the standard, it is necessary to add excessive sodium carbonate, which will increase the treatment cost.

[0138] (3) Based on a comprehensive analysis of Examples 1 and 6-7, it can be seen that the amount of sodium carbonate added in step (2) will affect the removal effect of calcium ions in wastewater. When the amount of sodium carbonate added is too low, the removal of calcium ions will be incomplete. Conversely, when the amount of sodium carbonate added is too high, the cost will be higher.

[0139] (4) Comprehensive analysis of Examples 1 and 8-9 shows that the pH of the environment during the deep defluorination process (step (3)) will affect the defluorination effect; when the pH value of the environment is too low or too high, the fluoride ion concentration will be too high and the emission standard will not be met.

[0140] (5) Comprehensive analysis of Examples 1 and 10-11 shows that the amount of sodium hypochlorite added will affect the deep oil removal effect. When the amount of sodium hypochlorite added is too low, the oil removal rate will be low. Conversely, when the amount of sodium hypochlorite added is too high, the cost will be high and the excessive sodium hypochlorite in the treated water will cause secondary pollution.

[0141] (6) Comprehensive analysis of Example 1 and Comparative Example 1 shows that if the preliminary defluorination and deoiling process is omitted and defluorinating agent and oxidant are directly used for deep defluorination and deoiling, the impurity ions in the treated water will not meet the discharge standards. If the impurity concentration is to be reduced, a large amount of defluorinating agent and sodium hypochlorite will be added, which will increase the treatment cost.

[0142] (7) Comprehensive analysis of Example 1 and Comparative Example 2 shows that compared with using sodium hypochlorite as an oxidant, if potassium permanganate, hydrogen peroxide and other oxidants are used to remove oil, the oil in the wastewater cannot be removed efficiently, making it unable to meet the discharge standards.

[0143] (8) Comprehensive analysis of Example 1 and Comparative Example 3 shows that changing the order of deep degreasing and deep defluorination will result in a higher pH value in the treatment system, a decrease in the oxidation performance of sodium hypochlorite, and consequently a higher oil content.

[0144] In summary, the treatment method provided by this invention can effectively reduce fluoride ions and oil content in wastewater, meeting wastewater discharge standards. In addition, the treatment method is low in cost, low in energy consumption, pollution-free, and simple to operate, and has significant application prospects.

[0145] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for treating wastewater from hydrometallurgical extraction, characterized in that, The processing method includes the following steps: (1) Mix the extraction wastewater and calcium source, stir once, and then perform solid-liquid separation to obtain the first filtrate, so as to achieve the preliminary treatment of fluoride ions and oil in the wastewater; (2) Mix the first filtrate and carbonate, stir twice, and then filter to remove calcium to obtain the second filtrate; (3) After mixing the second filtrate and the defluorinating agent, acid-base adjustment, stirring three times and solid-liquid separation are performed in sequence to obtain the third filtrate; (4) Mix the third filtrate and sodium hypochlorite solution, and stir four times to obtain treated clean water, so as to achieve deep treatment of oil in wastewater.

2. The processing method according to claim 1, characterized in that, The fluoride ion content in the extraction wastewater in step (1) is ≥150 mg / L.

3. The processing method according to claim 1, characterized in that, The oil content in the extraction wastewater in step (1) is ≥80mg / L.

4. The processing method according to claim 1, characterized in that, The calcium source in step (1) includes any one or a combination of at least two of calcium hydroxide, calcium oxide, or calcium chloride.

5. The processing method according to claim 4, characterized in that, In step (1), the molar ratio of fluoride ions in the extraction wastewater to calcium ions in the calcium source is 1:8~12.

6. The processing method according to claim 1, characterized in that, The stirring time in step (1) is 30~120 min.

7. The processing method according to claim 1, characterized in that, The carbonate in step (2) includes sodium carbonate.

8. The processing method according to claim 7, characterized in that, Ca in the first filtrate 2+ CO3 in carbonates 2- The molar ratio is 1:2~2.

5.

9. The processing method according to claim 1, characterized in that, The formula for calculating the amount w of the defluorinating agent added in step (3) is as follows: w=c(F - )×V×m×n Wherein, c(F) - ) represents F in the second filtrate - Concentration, V is the volume of the second filtrate, m is the magnification factor, and n is the theoretical excess coefficient of the defluorinating agent.

10. The processing method according to claim 9, characterized in that, The value of m ranges from 3 to 5.

11. The processing method according to claim 1, characterized in that, The reagents used for acid-base adjustment in step (3) include any one or a combination of at least two of hydrochloric acid, sulfuric acid, or nitric acid.

12. The processing method according to claim 11, characterized in that, The endpoint of the acid-base adjustment in step (3) is a pH value of 7-8.

13. The processing method according to claim 1, characterized in that, The stirring time for the three times in step (3) is 8~12 minutes.

14. The processing method according to claim 1, characterized in that, The amount of sodium hypochlorite solution added in step (4) is 2~15 mL / L.

15. The processing method according to claim 14, characterized in that, The amount of sodium hypochlorite solution added in step (4) is 8~10 mL / L.

16. The processing method according to claim 14, characterized in that, The concentration of the sodium hypochlorite solution in step (4) is 10~15wt%.

17. The processing method according to claim 1, characterized in that, The time for the four stirrings in step (4) is 2 to 4.5 hours.

18. The processing method according to any one of claims 1-17, characterized in that, The processing method includes the following steps: (1) Mix the extraction wastewater and calcium source, stir for 30-120 min at a time, and then perform solid-liquid separation to obtain the first filtrate, so as to achieve deep treatment of oil in the wastewater; The fluoride ion content in the extraction wastewater is ≥150mg / L, and the oil content is ≥80mg / L. The molar ratio of fluoride ions in the extraction wastewater to calcium ions in the calcium source is 1:8~12; (2) Mix the first filtrate and sodium carbonate, stir twice, and then filter to remove calcium to obtain the second filtrate; Among them, Ca in the first filtrate 2+ CO3 in carbonates 2- The molar ratio is 1:2~2.5; (3) After mixing the second filtrate and the defluorinating agent, the pH value is adjusted to 7-8, stirred three times for 8-12 minutes, and then separated into solid and liquid to obtain the third filtrate; Wherein, the amount of the defluorinating agent added is w = c(F - )×V×m×n,c(F - ) represents F in the second filtrate - Concentration, V is the volume of the second filtrate, m is the magnification factor, and n is the theoretical excess coefficient of the defluorinating agent; (4) Mix the third filtrate with a sodium hypochlorite solution with a concentration of 10~15wt%, stir four times for 2~4.5h to obtain treated clean water, so as to achieve deep treatment of oil in wastewater.

Images