Process method for resource utilization of evaporation mother liquor of deep coal bed gas produced wastewater
By adjusting the pH value and using an evaporation and concentration process to treat the mother liquor from deep coalbed methane production wastewater, qualified strontium carbonate and calcium chloride products were produced. This solved the problem of the difficulty in utilizing the mother liquor as a resource and achieved effective recycling of economic benefits and resources.
Patent Information
- Application Number
- CN202511144778.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-15
- Publication Date
- 2025-11-11
AI Technical Summary
In existing technologies, the treatment of evaporation mother liquor from deep coalbed methane produced water faces the problem of high concentrations of inorganic salts, trace heavy metals, and residual organic matter, which are difficult to utilize as resources. Traditional treatment methods also have drawbacks such as leakage risks and resource consumption.
By adjusting the pH value and treating the evaporation mother liquor with quicklime milk for pretreatment, the liquor is then evaporated, concentrated, and kept warm to precipitate strontium. After calcium precipitation, strontium carbonate and calcium chloride are prepared, thus achieving resource utilization.
This method achieves efficient resource utilization, produces qualified strontium carbonate and calcium chloride products, reduces calcium ion loss, and yields significant economic benefits.
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Figure CN120923076A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of wastewater treatment technology, specifically a process for the resource utilization of mother liquor from the evaporation of deep coalbed methane produced wastewater. Background Technology
[0002] The development of unconventional natural gas such as coalbed methane and shale gas generates large amounts of extraction wastewater. Improper treatment of this wastewater can cause serious pollution to soil, groundwater, and the ecological environment. Currently, a certain area in Shanxi Province is using a "pretreatment + multi-effect evaporation" process for its extraction wastewater. Multi-effect evaporation (MED) technology is widely used for treating this type of wastewater due to its high efficiency and stable desalination performance. It can effectively separate most inorganic salts from water. However, how to treat the mother liquor, which still contains high concentrations of inorganic salts (such as sodium chloride and calcium chloride), trace heavy metals, and residual organic matter, remains a challenging problem.
[0003] The high concentration of the mother liquor from evaporation makes it prone to scaling, hindering its resource utilization. Traditional treatment methods include solidification landfill and deep well reinjection. However, both methods have significant drawbacks. Solidification landfill carries a long-term risk of leakage and consumes land resources; deep well reinjection requires strict geological conditions and is prohibited by regulations in some regions. None of these methods achieve effective resource recycling.
[0004] Therefore, developing a process that can effectively utilize evaporation mother liquor, making the resource utilization of evaporation mother liquor a key research direction in the industry. Summary of the Invention
[0005] The purpose of this invention is to address the problems existing in the prior art by providing a process for the resource utilization of evaporation mother liquor from deep coalbed methane production wastewater. This method addresses the characteristic that the evaporation mother liquor mainly contains high levels of elements such as calcium and strontium. It utilizes a simple process to utilize the production wastewater as a resource. Specifically, the pH is adjusted to remove Mg2+ from the mother liquor. After filtration of the precipitate, the evaporation mother liquor is further evaporated and concentrated. After evaporation to a certain extent, it is centrifuged to separate the salts. The mother liquor obtained after salt separation is kept at a certain temperature to precipitate strontium, and then centrifuged again to separate the salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further evaporated and concentrated to obtain calcium chloride. The strontium-rich mixed salts are further treated and purified with water to obtain industrial-grade strontium carbonate.
[0006] To achieve the above-mentioned objectives, the specific technical solution of this invention is as follows: A process for the resource utilization of mother liquor from the evaporation of deep coalbed methane produced wastewater includes the following steps: S1. Pretreatment: Prepare lime slurry with quicklime, and slowly add the prepared lime slurry to the evaporating mother liquor under stirring. Adjust the pH, filter after reaction, and obtain the pretreated mother liquor. S2, Evaporation and Concentration: The pretreated mother liquor obtained in S1 is evaporated and concentrated to obtain the evaporated and concentrated mother liquor. S3, Strontium precipitation and calcium chloride preparation: The mother liquor obtained from S2 after evaporation and concentration is subjected to strontium precipitation treatment in a water bath to obtain strontium-rich mixed salt and strontium-removed mother liquor respectively; the strontium-removed mother liquor is further evaporated and concentrated to obtain the product calcium chloride salt; S4, Insulation and Calcium Precipitation: Dissolve the strontium-rich mixed salt obtained in S3 with pure water by stirring, and then heat it; after the temperature rises, add sodium hydroxide to carry out the insulation and calcium precipitation reaction, filter while hot to obtain calcium precipitation filtrate; S5. Preparation of Strontium carbonate: The calcium precipitation filtrate obtained in S4 is heated further, and Na2CO3 is added to the filtrate to react and then filtered to obtain crude Strontium carbonate; the crude Strontium carbonate is washed with an equal mass of pure water and dried to obtain Strontium carbonate.
[0007] Furthermore, in step S1 of the process for resource utilization of mother liquor from deep coalbed methane produced wastewater, the pH is adjusted to 10.5, and the reaction time is 1 hour.
[0008] Furthermore, in S2 of the process for resource utilization of evaporation mother liquor from deep coalbed methane produced wastewater, the final temperature of evaporation and concentration is 130°C, and the salt is separated after maintaining the temperature at 130°C.
[0009] Furthermore, in step S3 of the process for resource utilization of evaporation mother liquor from deep coalbed methane produced wastewater, the temperature for strontium precipitation treatment in the water bath is 50°C, and the treatment time is 4 hours.
[0010] Furthermore, in step S3 of the process for resource utilization of evaporation mother liquor from deep coalbed methane produced wastewater, the evaporation and concentration temperature of the strontium-removed mother liquor is 178°C.
[0011] Furthermore, in step S4 of the aforementioned process for the resource utilization of evaporation mother liquor from deep coalbed methane produced wastewater, the mass ratio of strontium-rich mixed salts to pure water is 1:1; the temperature is raised to 90°C; and based on the Ca content in the strontium-rich mother liquor... 2+ Add 5% excess sodium hydroxide to the reaction solution and react for ≥1 hour.
[0012] Furthermore, in step S5 of the process for resource utilization of evaporation mother liquor from deep coalbed methane produced wastewater, the temperature after further heating is 90°C; based on the Sr content in the filtrate... 2+ The reaction equivalent of Na2CO3 is added in excess by 10%; the reaction time is ≥3h.
[0013] Furthermore, in step S5 of the process for resource utilization of mother liquor from deep coalbed methane produced wastewater, the drying temperature is 110°C and the drying time is 4 hours.
[0014] Furthermore, in the aforementioned process for the resource utilization of evaporation mother liquor from deep coalbed methane produced wastewater, the evaporation mother liquor is coalbed methane evaporation mother liquor, whose main components are Sr, Ca, Mg, Na, Cl, and K.
[0015] Compared with the prior art, the positive effects of the present invention are reflected in: (1) Resource utilization treatment of evaporation mother liquor from deep coalbed methane mining wastewater in Shanxi Province. Through a simple process, the mining wastewater is recycled to obtain qualified strontium carbonate and calcium chloride products, generating certain economic benefits.
[0016] (2) This process is a magnesium removal method with less calcium ion loss when the mother liquor contains high calcium.
[0017] (3) This process is for the separation of calcium and strontium from coalbed methane extraction wastewater and the preparation of strontium carbonate. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the process flow for the resource utilization of mother liquor from the evaporation of deep coalbed methane produced according to the present invention. Detailed Implementation
[0019] A process for the resource utilization of mother liquor from the evaporation of deep coalbed methane produced wastewater includes the following steps: S1. Pretreatment: Prepare lime slurry with quicklime, and slowly add the prepared lime slurry to the evaporating mother liquor under stirring. Adjust the pH, filter after reaction, and obtain the pretreated mother liquor. S2, Evaporation and Concentration: The pretreated mother liquor obtained in S1 is evaporated and concentrated to obtain the evaporated and concentrated mother liquor. S3, Strontium precipitation and calcium chloride preparation: The mother liquor obtained from S2 after evaporation and concentration is subjected to strontium precipitation treatment in a water bath to obtain strontium-rich mixed salts and strontium-removed mother liquor, respectively. S4, Insulation and Calcium Precipitation: Dissolve the strontium-rich mixed salt obtained in S3 with pure water by stirring, and then heat it; after the temperature rises, add sodium hydroxide to carry out the insulation and calcium precipitation reaction, filter while hot to obtain calcium precipitation filtrate; S5. Preparation of Strontium carbonate: The calcium precipitation filtrate obtained in S4 is heated further, and Na2CO3 is added to the filtrate to react and then filtered to obtain crude Strontium carbonate; the crude Strontium carbonate is washed with an equal mass of pure water and dried to obtain Strontium carbonate; S6. Preparation of calcium chloride: The strontium-free mother liquor obtained in S3 is further evaporated and concentrated to obtain the product calcium chloride salt.
[0020] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0021] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] In this application, all percentages not explicitly stated represent mass percentage content.
[0024] In this invention, some conventional operating equipment, devices and components have been omitted or only briefly described.
[0025] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0026] The evaporation mother liquor used in the following examples is coalbed methane evaporation mother liquor, and its reference composition is shown in the table below.
[0027] Coalbed methane evaporation mother liquor, raw material reference composition table:
[0028] Example 1: A process for the resource utilization of mother liquor from the evaporation of deep coalbed methane produced wastewater, based on specific implementation methods, follows... Figure 1 The process flow diagram described above is used for preparation: Using the mother liquor from evaporation (reference components of raw materials are shown in the table above) as raw material, lime slurry was prepared with CaO; the pH was first adjusted by adding the lime slurry prepared with CaO to the container for pretreatment, and after reacting for 1 hour, the mixture was filtered to remove Mg from the mother liquor. 2+Pretreated effluent is obtained. The filtered mother liquor (pretreated effluent) is evaporated and concentrated, and its evaporation endpoint temperature is controlled. After evaporation to a certain extent, it is centrifuged and desalted while maintaining the temperature. The concentrated mother liquor (i.e., the mother liquor after evaporation and desalting, also known as evaporated effluent) is placed in a water bath for strontium precipitation. After strontium precipitation for a period of time, it is centrifuged and desalted while maintaining the temperature, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are added to an equal mass of pure water and stirred to dissolve. After dissolution, NaOH is added to adjust the pH and boiled. After 1 hour, it is filtered while hot to obtain Ca(OH)2 sludge and strontium-rich mother liquor (i.e., calcium precipitation filtrate). Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. After reacting for 3 hours, the precipitate is filtered and the precipitate is washed (washed with an equal mass of pure water) and dried (dried at 110℃ for 4 hours) to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and desalting section. The parameters for each process section are shown in Table 1.1, the effluent quality is shown in Table 1.2, and the salt composition of the product is shown in Table 1.3.
[0029] Table 1.1 Control parameters for each section in Example 1
[0030] Table 1.2 Components of Effluent
[0031] Table 1.3 Salt composition of the product
[0032] Example 2: A process for the resource utilization of mother liquor from the evaporation of deep coalbed methane produced wastewater, based on specific implementation methods, follows... Figure 1 The process flow diagram described above is used for preparation: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), lime slurry was prepared with CaO; the pH was first adjusted by adding the lime slurry prepared with CaO for pretreatment, and after reacting for 1 hour, the mixture was filtered to remove Mg from the mother liquor. 2+Pretreated effluent is obtained. The filtered mother liquor (pretreated effluent) is evaporated and concentrated, and its evaporation endpoint temperature is controlled. After evaporation to a certain extent, it is centrifuged and desalted while maintaining the temperature. The concentrated mother liquor (i.e., the mother liquor after evaporation and desalting, also known as evaporated effluent) is placed in a water bath for strontium precipitation. After strontium precipitation for a period of time, it is centrifuged and desalted while maintaining the temperature, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are added to an equal mass of pure water and stirred to dissolve. After dissolution, NaOH is added to adjust the pH and boiled. After 1 hour, it is filtered while hot to obtain Ca(OH)2 sludge and strontium-rich mother liquor (i.e., calcium precipitation filtrate). Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. After reacting for 3 hours, the precipitate is filtered and the precipitate is washed (washed with an equal mass of pure water) and dried (dried at 110℃ for 4 hours) to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and desalting section. The parameters for each process section are shown in Table 2.1, the effluent quality is shown in Table 2.2, and the salt composition of the product is shown in Table 2.3.
[0033] Table 2.1 Control parameters for each section
[0034] Table 2.2 Effluent water composition
[0035] Table 2.3 Salt composition of the product
[0036] Example 3: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), the pH was first adjusted by adding lime milk prepared with CaO for pretreatment. After reacting for 1 hour, the mixture was filtered to remove Mg from the mother liquor. 2+ Pretreated effluent is obtained. The filtered mother liquor (pretreated effluent) is evaporated and concentrated, and its evaporation endpoint temperature is controlled. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate the salts, obtaining evaporated effluent. The concentrated mother liquor (i.e., the mother liquor after evaporation and salt separation, also called evaporated effluent) is placed in a water bath for strontium precipitation. After strontium precipitation for a period of time, it is kept at a certain temperature and centrifuged to separate the salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are dissolved in an equal mass of pure water. After dissolution, NaOH is added to adjust the pH and boiled. After 1 hour, it is kept hot and filtered to obtain Ca(OH)2 sludge and strontium-rich mother liquor (i.e., calcium precipitation filtrate). Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. After reacting for 3 hours, the precipitate is filtered and the precipitate is washed (washed with an equal mass of pure water) and dried (dried at 110℃ for 4 hours) to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and salt separation section. The parameters for each process section are shown in Table 3.1, the effluent quality is shown in Table 3.2, and the salt composition of the product is shown in Table 3.3.
[0037] Table 3.1 Control parameters for each section
[0038] Table 3.2 Components of Effluent
[0039] Table 3.3 Salt composition of the product
[0040] Example 4: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), the pH was first adjusted by adding lime milk prepared with CaO for pretreatment. After reacting for 1 hour, the mixture was filtered to remove Mg from the mother liquor. 2+ The pretreated effluent is obtained. The filtered mother liquor (pretreated effluent) is evaporated and concentrated. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate the salts, obtaining evaporated effluent. The concentrated mother liquor (i.e., the mother liquor after evaporation and salt separation, also called evaporated effluent) is placed in a water bath for strontium precipitation. After strontium precipitation for a period of time, its evaporation endpoint temperature is controlled. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate the salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are dissolved in an equal mass of pure water. After dissolution, NaOH is added to adjust the pH and boiled. After 1 hour, it is kept hot and filtered to obtain Ca(OH)2 sludge and strontium-rich mother liquor (i.e., calcium precipitation filtrate). Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. After reacting for 3 hours, the precipitate is filtered and the precipitate is washed (washed with an equal mass of pure water) and dried (dried at 110℃ for 4 hours) to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and salt separation section. The parameters for each process section are shown in Table 4.1, the effluent quality is shown in Table 4.2, and the salt composition of the product is shown in Table 4.3.
[0041] Table 4.1 Control parameters for each section
[0042] Table 4.2 Effluent water composition
[0043] Table 4.3 Salt composition of the product
[0044] Example 5: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), the pH was first adjusted by adding lime milk prepared with CaO for pretreatment. After reacting for 1 hour, the mixture was filtered to remove Mg from the mother liquor. 2+The pretreated effluent is obtained. The filtered mother liquor (pretreated effluent) is evaporated and concentrated. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate the salts, obtaining evaporated effluent. The concentrated mother liquor (i.e., the mother liquor after evaporation and salt separation, also called evaporated effluent) is placed in a water bath for strontium precipitation. After strontium precipitation for a period of time, it is kept at a certain temperature and centrifuged to separate the salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are dissolved in an equal mass of pure water. After dissolution, NaOH is added to adjust the pH and boiled. After 1 hour, it is kept hot and filtered to obtain Ca(OH)2 sludge and strontium-rich mother liquor (i.e., calcium precipitation filtrate). Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. After reacting for 3 hours, the precipitate is filtered and the precipitate is washed (washed with an equal mass of pure water) and dried (dried at 110℃ for 4 hours) to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and salt separation section. The parameters for each process section are shown in Table 5.1, the effluent quality is shown in Table 5.2, and the salt composition of the product is shown in Table 5.3.
[0045] Table 5.1 Control parameters for each section
[0046] Table 5.2 Effluent water composition
[0047] Table 5.3 Salt composition of the product
[0048] Example 6: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), the pH was first adjusted by adding lime milk prepared with CaO for pretreatment. After reacting for 1 hour, the mixture was filtered to remove Mg from the mother liquor. 2+ Pretreated effluent is obtained. The filtered mother liquor (pretreated effluent) is evaporated and concentrated, and its evaporation endpoint temperature is controlled. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate salts, obtaining evaporated effluent. The concentrated mother liquor (i.e., the mother liquor after evaporation and salt separation, also called evaporated effluent) is placed in a water bath for strontium precipitation. After strontium precipitation for a period of time, it is kept at a certain temperature and centrifuged to separate salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are dissolved in an equal mass of pure water. After dissolution, NaOH is added to adjust the pH and boiled. After 1 hour, it is kept hot and filtered to obtain Ca(OH)2 sludge and strontium-rich mother liquor (i.e., calcium precipitation filtrate). Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. After reacting for 3 hours, the precipitate is filtered and the precipitate is washed (washed with an equal mass of pure water) and dried (dried at 110℃ for 4 hours) to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and salt separation section. The parameters for each process section are shown in Table 6.1, the effluent quality is shown in Table 6.2, and the salt composition of the product is shown in Table 6.3.
[0049] Table 6.1 Control parameters for each section
[0050] Table 6.2 Effluent water composition
[0051] Table 6.3 Salt composition of the product
[0052] Example 7: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), the pH was first adjusted by adding lime milk prepared with CaO for pretreatment. After reacting for 1 hour, the mixture was filtered to remove Mg from the mother liquor. 2+ Pretreated effluent is obtained. The filtered mother liquor (pretreated effluent) is evaporated and concentrated, and its evaporation endpoint temperature is controlled. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate the salts, obtaining evaporated effluent. The concentrated mother liquor (i.e., the mother liquor after evaporation and salt separation, also called evaporated effluent) is placed in a water bath for strontium precipitation. After strontium precipitation for a period of time, it is kept at a certain temperature and centrifuged to separate the salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are dissolved in an equal mass of pure water. After dissolution, NaOH is added to adjust the pH and boiled. After 1 hour, it is kept hot and filtered to obtain Ca(OH)2 sludge and strontium-rich mother liquor (i.e., calcium precipitation filtrate). Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. After reacting for 3 hours, the precipitate is filtered, washed (washed with an equal mass of pure water), and dried (dried at 110℃ for 4 hours) to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and salt separation section. The parameters for each process section are shown in Table 7.1, the effluent quality is shown in Table 7.2, and the salt composition of the product is shown in Table 7.3.
[0053] Table 7.1 Control parameters for each section
[0054] Table 7.2 Components of Effluent
[0055] Table 7.3 Salt composition of the product
[0056] Example 8: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), the pH was first adjusted by adding lime milk prepared with CaO for pretreatment. After reacting for 1 hour, the mixture was filtered to remove Mg from the mother liquor. 2+Pretreated effluent is obtained. The filtered mother liquor (pretreated effluent) is evaporated and concentrated. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate the salts, obtaining evaporated effluent. The concentrated mother liquor (i.e., the mother liquor after evaporation and salt separation, also called evaporated effluent) is placed in a water bath for strontium precipitation. After strontium precipitation for a period of time, it is kept at a certain temperature and centrifuged to separate the salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are dissolved in an equal mass of pure water. After dissolution, NaOH is added to adjust the pH and boiled. After 1 hour, it is filtered while hot to obtain Ca(OH)2 sludge and strontium-rich mother liquor (i.e., calcium precipitation filtrate). Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. After reacting for 3 hours, the precipitate is filtered, and the precipitate is filtered, washed, and dried to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and salt separation section. The parameters for each process section are shown in Table 8.1, the effluent quality is shown in Table 8.2, and the salt composition of the product is shown in Table 8.3.
[0057] Table 8.1 Control parameters for each work section
[0058] Table 8.2 Effluent water composition
[0059] Table 8.3 Salt composition of the product
[0060] Comparative Example 1: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), the pH is first adjusted by adding lime milk prepared with CaO to remove Mg from the mother liquor. 2+ The filtered mother liquor is evaporated and concentrated. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate the salts. The concentrated mother liquor is kept at a certain temperature to precipitate strontium. After strontium precipitation for a period of time, it is kept at a certain temperature and centrifuged to separate the salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are dissolved in an equal mass of pure water. After dissolution, NaOH is added to adjust the pH and the mixture is boiled. After a period of time, it is filtered to obtain Ca(OH)2 sludge and strontium-rich mother liquor. Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. The precipitate is filtered, washed, and dried to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and salt separation section. The parameters of each section are shown in Table 9.1, the effluent water quality is shown in Table 9.2, and the product salt composition is shown in Table 9.3.
[0061] The results showed that the magnesium was not completely removed after pretreatment, which resulted in the calcium chloride and strontium carbonate in the product failing to meet industrial standards.
[0062] Table 9.1 Control parameters for each work section
[0063] Table 9.2 Effluent water composition
[0064] Table 9.3 Salt composition of the product
[0065] Comparative Example 2: Using the mother liquor from evaporation as raw material (the composition of the raw material is the same as in Example 1), the pH is first adjusted by adding lime milk prepared with CaO to remove Mg from the mother liquor. 2+ The filtered mother liquor is evaporated and concentrated. After evaporation to a certain extent, it is kept at a certain temperature and centrifuged to separate the salts. The concentrated mother liquor is kept at a certain temperature to precipitate strontium. After strontium precipitation for a period of time, it is kept at a certain temperature and centrifuged to separate the salts, obtaining strontium-precipitated mother liquor and strontium-rich mixed salts. The strontium-precipitated mother liquor is further concentrated to obtain industrial-grade CaCl2. The strontium-rich mixed salts are dissolved in an equal mass of purified water. After dissolution, NaOH is added to adjust the pH and the mixture is boiled. After a period of time, it is filtered to obtain Ca(OH)2 sludge and strontium-rich mother liquor. Na2CO3 is added to the strontium-rich mother liquor to precipitate strontium. The precipitate is filtered, washed, and dried to obtain industrial-grade SrCO3. The filtrate is returned to the evaporation and salt separation section. The parameters of each section are shown in Table 10.1, the effluent quality is shown in Table 10.2, and the product salt composition is shown in Table 10.3.
[0066] The results showed that the purity of the prepared calcium chloride and strontium carbonate was not high and did not meet the industrial-grade standard.
[0067] Table 10.1 Control parameters for each section
[0068] Table 10.2 Effluent water composition
[0069] Table 10.3 Salt composition of the product
[0070] .
[0071] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.
[0072] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.
Claims
1. A process for the resource utilization of mother liquor from the evaporation of deep coalbed methane produced wastewater, characterized in that... Includes the following steps: S1. Pretreatment: Prepare lime slurry with quicklime, and slowly add the prepared lime slurry to the evaporating mother liquor under stirring. Adjust the pH, filter after reaction, and obtain the pretreated mother liquor. S2, Evaporation and Concentration: The pretreated mother liquor obtained in S1 is evaporated and concentrated to obtain the evaporated and concentrated mother liquor. S3, Strontium precipitation and calcium chloride preparation: The mother liquor obtained from S2 after evaporation and concentration is subjected to strontium precipitation treatment in a water bath to obtain strontium-rich mixed salt and strontium-removed mother liquor respectively; the strontium-removed mother liquor is further evaporated and concentrated to obtain the product calcium chloride salt; S4, Insulation and Calcium Precipitation: Dissolve the strontium-rich mixed salt obtained in S3 with pure water by stirring, and then heat it; after the temperature rises, add sodium hydroxide to carry out the insulation and calcium precipitation reaction, filter while hot to obtain calcium precipitation filtrate; S5. Preparation of Strontium carbonate: The calcium precipitation filtrate obtained in S4 is heated further, and Na2CO3 is added to the filtrate to react and then filtered to obtain crude Strontium carbonate; the crude Strontium carbonate is washed with an equal mass of pure water and dried to obtain Strontium carbonate.
2. The process for resource utilization of mother liquor from deep coalbed methane produced wastewater according to claim 1, characterized in that: Adjust the pH to 10.5 in S1 and react for 1 hour.
3. The process for resource utilization of mother liquor from deep coalbed methane produced wastewater according to claim 1, characterized in that: The final temperature for evaporation and concentration in S2 is 130℃, and the salt is separated after maintaining the temperature at 130℃.
4. The process for resource utilization of mother liquor from deep coalbed methane produced wastewater according to claim 1, characterized in that: In S3, the temperature for strontium precipitation treatment in the water bath is 50℃, and the treatment time is 4 hours.
5. The process for resource utilization of mother liquor from deep coalbed methane produced wastewater evaporation according to claim 1, characterized in that: The evaporation and concentration temperature of the strontium-removed mother liquor in S3 is 178℃.
6. The process for resource utilization of mother liquor from deep coalbed methane produced wastewater according to claim 1, characterized in that: In S4, the mass ratio of strontium-rich mixed salts to pure water is 1:1; the temperature is raised to 90℃; based on the Ca in the strontium-rich mother liquor... 2+ Add 5% excess sodium hydroxide to the reaction solution and react for ≥1 hour.
7. The process for resource utilization of mother liquor from deep coalbed methane produced wastewater according to claim 1, characterized in that: The temperature after further heating in S5 is 90℃.
8. The process for resource utilization of mother liquor from deep coalbed methane produced wastewater according to claim 1, characterized in that: S5 is based on the Sr in the filtrate 2+ The reaction equivalent of Na2CO3 is added in excess by 10%; the reaction time is ≥3h.
9. The process for resource utilization of mother liquor from deep coalbed methane produced wastewater evaporation according to claim 1, characterized in that: The drying temperature in S5 is 110℃, and the drying time is 4 hours.
10. A process for resource utilization of mother liquor from deep coalbed methane produced wastewater according to any one of claims 1-9, characterized in that: The evaporation mother liquor is coalbed methane evaporation mother liquor, and its main components are Sr, Ca, Mg, Na, Cl, and K.