CN112374679A - Treatment method of wastewater generated in cobaltosic oxide preparation process - Google Patents
Treatment method of wastewater generated in cobaltosic oxide preparation process Download PDFInfo
- Publication number
- CN112374679A CN112374679A CN202011188816.3A CN202011188816A CN112374679A CN 112374679 A CN112374679 A CN 112374679A CN 202011188816 A CN202011188816 A CN 202011188816A CN 112374679 A CN112374679 A CN 112374679A
- Authority
- CN
- China
- Prior art keywords
- filtrate
- cobaltosic oxide
- filter residue
- wastewater generated
- wastewater
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/04—Chlorides
- C01D3/06—Preparation by working up brines; seawater or spent lyes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Removal Of Specific Substances (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
The invention discloses a method for treating wastewater generated in the process of preparing cobaltosic oxide, which comprises the following steps: performing primary filtration on wastewater generated in the cobaltosic oxide preparation process to obtain a first filtrate and a first filter residue; heating the first filtrate to 50-60 ℃, adding sodium hypochlorite, uniformly mixing, and adding sodium hydroxide to adjust the pH value of the first filtrate to 10-12; filtering the mixed solution for the second time to obtain second filter residue and second filtrate; and adjusting the pH value of the second filtrate to 6.5-7.5, and then carrying out evaporation crystallization to obtain sodium chloride and distilled water. According to the invention, the complex cobalt is broken by adding sodium hypochlorite, so that cobalt in the wastewater is converted into hydroxide precipitate, and the content of cobalt metal ions in the wastewater produced by cobaltosic oxide is effectively reduced. The filtered wastewater is subjected to pH value adjustment to be neutral and then is subjected to evaporative crystallization to obtain sodium chloride and distilled water, and the distilled water can be recycled as pure water, so that the process is clean and the cost is saved.
Description
Technical Field
The invention belongs to the field of sewage treatment, and particularly relates to a method for treating wastewater generated in a cobaltosic oxide preparation process.
Background
The cobaltosic oxide is a main raw material for preparing lithium cobaltate serving as a cathode material of the lithium ion battery, and due to the rapid development of the lithium ion battery, the output and the annual consumption of the cobaltosic oxide in China are in the forefront of the world. In the production process of cobaltosic oxide, a large amount of high-concentration cobalt-containing wastewater is generated. Currently, adsorption, chemical precipitation and ion exchange methods are the most common methods for treating cobalt-containing wastewater.
Most of the adsorption methods are still in the research stage and are suitable for treating the low-concentration cobalt-containing wastewater. The core of the method lies in the selection of the adsorbent, while the traditional adsorbent has high cost and difficult regeneration, and a novel and cheap adsorbent is still under development and research. The main mechanism of the ion exchange resin method is to utilize functional groups such as hydroxyl, amino, carboxyl and the like in the ion exchange resin to generate chelation with heavy metal ions, so as to effectively adsorb the heavy metal ions, but the ion exchange resin method has higher requirement on the quality of inlet water, is greatly influenced by the inlet water quality, has higher regeneration cost of the resin, and is difficult to apply on a large scale. The chemical precipitation method is the most widely applied method in the field of cobalt-containing wastewater treatment, has low cost and easy operation, but because the cobaltosic oxide production wastewater usually contains inorganic or organic ligands such as ammonia nitrogen, an extracting agent and the like, the existence form of cobalt ions in a water body can be changed, so that the cobalt ions are difficult to precipitate, and the effluent is difficult to reach the standard.
Disclosure of Invention
In order to solve the problem that the conventional chemical precipitation is difficult to remove and separate in the prior art, the invention aims to provide a method for treating wastewater generated in the process of preparing cobaltosic oxide.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a method for treating wastewater generated in the process of preparing cobaltosic oxide comprises the following steps:
(1) performing primary filtration on wastewater generated in the cobaltosic oxide preparation process to obtain a first filtrate and a first filter residue;
(2) heating the first filtrate to 50-60 ℃, adding sodium hypochlorite, uniformly mixing, and adding sodium hydroxide to adjust the pH value of the first filtrate to 10-12; and filtering the mixed solution for the second time to obtain a second filter residue and a second filtrate, wherein the mass concentration of the sodium hydroxide is 30-35%, the mass concentration of the sodium hypochlorite is 10-13%, and the volume ratio of the sodium hypochlorite to the sodium hydroxide is (3.0-3.5): 1;
(3) and adjusting the pH value of the second filtrate to 6.5-7.5, and then carrying out evaporation crystallization to obtain sodium chloride and distilled water.
(4) And (3) returning the first filter residue obtained in the step (1) and the second filter residue obtained in the step (2) to a production workshop for secondary purification and utilization.
Preferably, the first filtration and the second filtration in the step (1) and the step (2) are both filter-pressed by a plate-and-frame filter press. After filtration, the water is clear, colorless and transparent, and is slightly red before sodium hyposulfite and liquid alkali are added.
Preferably, the reagent for adjusting pH value in the step (3) is hydrochloric acid.
Preferably, the equipment for evaporative crystallization in step (3) is an MVR evaporator.
And (3) the heating temperature in the step (2) is 50-60 ℃, the precipitate formed by the reaction of the sodium hypochlorite and the cobalt in the wastewater at the temperature has good filtering performance, the precipitate is difficult to filter when the temperature is too low, and the energy consumption is increased when the temperature is too high.
The reaction principle of the invention is as follows: firstly, carrying out complex breaking treatment on the cobalt in the complex state in the wastewater through the added sodium hypochlorite, and aiming at changing the cobalt in the complex state into the cobalt in the ionic state, and then reacting the cobalt in the ionic state with sodium hydroxide and sodium hypochlorite, wherein the reaction formula is as follows:
Co2++2OH-→Co(OH)2
2Co(OH)2+ClO-+H2O→2Co(OH)3+Cl-
according to the invention, the complex cobalt is broken by adding sodium hypochlorite, so that cobalt in the wastewater is converted into hydroxide precipitate, and the content of cobalt metal ions in the wastewater produced by cobaltosic oxide is effectively reduced. The filtered wastewater is subjected to pH value adjustment to be neutral and then is subjected to evaporative crystallization to obtain sodium chloride, and the distilled water can be recycled as pure water, so that the process is clean, and the cost is saved.
Compared with the prior art, the invention has the following beneficial effects:
1. the method solves the problem that the cobalt in the wastewater generated in the process of preparing the cobaltosic oxide is difficult to separate by conventional chemical precipitation, and can effectively remove heavy metal ions in the wastewater;
2. the solid product finally obtained by the method comprises first filter residue (containing cobaltosic oxide), second filter residue (containing cobalt residue) and sodium chloride. The first filter residue and the second filter residue can be returned to a production workshop for secondary purification and utilization, sodium chloride can be sold as industrial salt, the final liquid product is distilled water, zero pollution emission is realized, and the environment is friendly;
3. the method provided by the invention has the advantages of simple process, easily controlled reaction conditions, great benefit and suitability for popularization and application.
Drawings
FIG. 1 is a flow chart of the processing method of the present invention.
Detailed Description
For further understanding of the present invention, the technical solutions of the present invention are further described below with reference to examples, but the present invention is not limited to these examples.
Example 1
A method for treating wastewater generated in the process of preparing cobaltosic oxide comprises the following steps:
(1) performing primary filtration on wastewater generated in the cobaltosic oxide preparation process by using a plate-and-frame filter press to obtain a first filtrate and a first filter residue;
(2) feeding the first filtrate into a reaction kettle, heating to 55 ℃, adding sodium hypochlorite with the mass concentration of 10%, uniformly mixing, adding sodium hydroxide with the mass concentration of 30%, and adjusting the pH value to 10; the volume ratio of the added sodium hypochlorite to the added sodium hydroxide is 3: 1, performing second plate-and-frame filtration on the mixed solution by adopting a plate-and-frame filter press to obtain second filter residue and second filtrate;
(3) and adding hydrochloric acid into the second filtrate to adjust the pH value to 7.2, and then carrying out evaporative crystallization by adopting an MVR evaporator to obtain sodium chloride and distilled water.
(4) And (3) returning the first filter residue obtained in the step (1) and the second filter residue obtained in the step (2) to a production workshop for secondary purification and utilization.
Example 2
A method for treating wastewater generated in the process of preparing cobaltosic oxide comprises the following steps:
(1) performing primary filtration on wastewater generated in the cobaltosic oxide preparation process by using a plate-and-frame filter press to obtain a first filtrate and a first filter residue;
(2) feeding the first filtrate into a reaction kettle, heating to 60 ℃, adding 10% by mass of sodium hypochlorite, uniformly mixing, adding 32% by mass of sodium hydroxide, adjusting the pH value to 12, wherein the volume ratio of the added sodium hypochlorite to the added sodium hydroxide is 3.2: 1; performing second plate-frame filtration on the mixed solution by adopting a plate-frame filter press to obtain second filter residue and second filtrate;
(3) and adding hydrochloric acid into the second filtrate to adjust the pH value to 6.5, and then carrying out evaporative crystallization by adopting an MVR evaporator to obtain sodium chloride and distilled water.
(4) And (3) returning the first filter residue obtained in the step (1) and the second filter residue obtained in the step (2) to a production workshop for secondary purification and utilization.
Example 3
A method for treating wastewater generated in the process of preparing cobaltosic oxide comprises the following steps:
(1) performing primary filtration on wastewater generated in the cobaltosic oxide preparation process by using a plate-and-frame filter press to obtain a first filtrate and a first filter residue;
(2) feeding the first filtrate into a reaction kettle, heating to 50 ℃, adding 13% by mass of sodium hypochlorite, uniformly mixing, adding 35% by mass of sodium hydroxide, adjusting the pH value to 13, wherein the volume ratio of the added sodium hypochlorite to the added sodium hydroxide is 3.5: 1; performing second plate-frame filtration on the mixed solution by adopting a plate-frame filter press to obtain second filter residue and second filtrate;
(3) and adding hydrochloric acid into the second filtrate to adjust the pH value to 7.5, and then carrying out evaporative crystallization by adopting an MVR evaporator to obtain sodium chloride and distilled water.
(4) And (3) returning the first filter residue obtained in the step (1) and the second filter residue obtained in the step (2) to a production workshop for secondary purification and utilization.
Comparative example 1
A method for treating wastewater generated in the process of preparing cobaltosic oxide comprises the following steps:
(1) performing primary filtration on wastewater generated in the cobaltosic oxide preparation process by using a plate-and-frame filter press to obtain a first filtrate and a first filter residue;
(2) feeding the first filtrate into a reaction kettle, heating to 40 ℃, adding sodium hypochlorite with the mass concentration of 10%, uniformly mixing, adding sodium hydroxide with the mass concentration of 32%, and adjusting the pH value to 9; the volume ratio of the added sodium hypochlorite to the added sodium hydroxide is 3.2: 1, performing second plate-and-frame filtration on the mixed solution by adopting a plate-and-frame filter press to obtain second filter residue and second filtrate;
(3) and adding hydrochloric acid into the second filtrate to adjust the pH value to 7, and then carrying out evaporative crystallization by adopting an MVR evaporator to obtain sodium chloride and distilled water.
(4) And (3) returning the first filter residue obtained in the step (1) and the second filter residue obtained in the step (2) to a production workshop for secondary purification and utilization.
Comparative example 2
A method for treating wastewater generated in the process of preparing cobaltosic oxide comprises the following steps:
(1) performing primary filtration on wastewater generated in the cobaltosic oxide preparation process by using a plate-and-frame filter press to obtain a first filtrate and a first filter residue;
(2) feeding the first filtrate into a reaction kettle, heating to 55 ℃, adding 10% by mass of sodium hypochlorite, uniformly mixing, adding 32% by mass of sodium hydroxide, adjusting the pH value to 11, wherein the volume ratio of the added sodium hypochlorite to the added sodium hydroxide is 2.5: 1; performing second plate-frame filtration on the mixed solution by adopting a plate-frame filter press to obtain second filter residue and second filtrate;
(3) and adding hydrochloric acid into the second filtrate to adjust the pH value to 7, and then carrying out evaporative crystallization by adopting an MVR evaporator to obtain sodium chloride and distilled water.
(4) And (3) returning the first filter residue obtained in the step (1) and the second filter residue obtained in the step (2) to a production workshop for secondary purification and utilization.
The same wastewater from the production of cobaltosic oxide was treated by the methods of examples 1 to 3 and comparative examples 1 and 2, and the cobalt contents of the final product sodium chloride and distilled water were measured, and the results are shown in table 1.
TABLE 1 final product sodium chloride and cobalt content in distilled water
| Numbering | Cobalt content (mg/L) in sodium chloride | Cobalt content (mg/L) in distilled water |
| Example 1 | 0 | 0 |
| Example 2 | 0 | 0 |
| Example 3 | 0 | 0 |
| Comparative example 1 | 0.043 | 0.35 |
| Comparative example 2 | 0.032 | 0.54 |
Detection shows that the sodium chloride and the distilled water in the wastewater treated in the examples 1-3 do not contain cobalt, and a small amount of cobalt is detected in the sodium chloride and the distilled water in the wastewater final products treated in the comparative examples 1 and 2, which indicates that when sodium hypochlorite is added to react with the cobalt complex, the heating temperature is proper at 50-60 ℃, the formed precipitate is easy to separate, the temperature is not completely reduced, and extra energy consumption is increased due to overhigh temperature. Meanwhile, the volume ratio of the sodium hypochlorite to the sodium hydroxide is (3.0-3.5): preferably 1.
Claims (4)
1. A method for treating wastewater generated in the process of preparing cobaltosic oxide is characterized by comprising the following steps:
(1) performing primary filtration on wastewater generated in the cobaltosic oxide preparation process to obtain a first filtrate and a first filter residue;
(2) heating the first filtrate to 50-60 ℃, adding sodium hypochlorite, uniformly mixing, and adding sodium hydroxide to adjust the pH value of the first filtrate to 10-12; and filtering the mixed solution for the second time to obtain a second filter residue and a second filtrate, wherein the mass concentration of the sodium hydroxide is 30-35%, the mass concentration of the sodium hypochlorite is 10-13%, and the volume ratio of the sodium hypochlorite to the sodium hydroxide is (3.0-3.5): 1;
(3) adjusting the pH value of the second filtrate to 6.5-7.5, and then carrying out evaporation crystallization to obtain sodium chloride and distilled water;
(4) and (3) returning the first filter residue obtained in the step (1) and the second filter residue obtained in the step (2) to a production workshop for secondary purification and utilization.
2. The method for treating wastewater generated in the process of preparing cobaltosic oxide according to claim 1, wherein the first filtration and the second filtration in the steps (1) and (2) are performed by pressure filtration by using a plate-and-frame filter press.
3. The method for treating wastewater generated in the process of preparing cobaltosic oxide according to claim 1, wherein the agent for adjusting the pH value in the step (3) is hydrochloric acid.
4. The method for treating wastewater generated in the process of preparing cobaltosic oxide according to claim 1, wherein the evaporative crystallization device in the step (3) is an MVR evaporator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011188816.3A CN112374679A (en) | 2020-10-30 | 2020-10-30 | Treatment method of wastewater generated in cobaltosic oxide preparation process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011188816.3A CN112374679A (en) | 2020-10-30 | 2020-10-30 | Treatment method of wastewater generated in cobaltosic oxide preparation process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112374679A true CN112374679A (en) | 2021-02-19 |
Family
ID=74576952
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011188816.3A Pending CN112374679A (en) | 2020-10-30 | 2020-10-30 | Treatment method of wastewater generated in cobaltosic oxide preparation process |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112374679A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116477805A (en) * | 2023-05-10 | 2023-07-25 | 苏州登峰环境工程有限公司 | Cobalt sulfamate electroless plating cleaning wastewater zero-emission treatment process |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103848490A (en) * | 2012-12-05 | 2014-06-11 | 宁波科博特钴镍有限公司 | Method for removing cobalt in cobalt-containing wastewater |
| CN108004406A (en) * | 2017-12-04 | 2018-05-08 | 中国恩菲工程技术有限公司 | Nickel and cobalt containing process for treating waste liquor |
| CN109292831A (en) * | 2018-11-23 | 2019-02-01 | 湖南中伟新能源科技有限公司 | A kind of processing method of cobaltosic oxide production waste water |
-
2020
- 2020-10-30 CN CN202011188816.3A patent/CN112374679A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103848490A (en) * | 2012-12-05 | 2014-06-11 | 宁波科博特钴镍有限公司 | Method for removing cobalt in cobalt-containing wastewater |
| CN108004406A (en) * | 2017-12-04 | 2018-05-08 | 中国恩菲工程技术有限公司 | Nickel and cobalt containing process for treating waste liquor |
| CN109292831A (en) * | 2018-11-23 | 2019-02-01 | 湖南中伟新能源科技有限公司 | A kind of processing method of cobaltosic oxide production waste water |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116477805A (en) * | 2023-05-10 | 2023-07-25 | 苏州登峰环境工程有限公司 | Cobalt sulfamate electroless plating cleaning wastewater zero-emission treatment process |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106315947B (en) | Treatment system and treatment process for heavy metal-containing industrial sewage | |
| CN101428933B (en) | Biological agent cooperated hydrolyzation-blowing off treatment process for nickel-ammonia wastewater | |
| CN101503435B (en) | Method for purifying stevioside by secondary ion exchange | |
| CN107162276A (en) | A kind of method for removing chromium of ferric trichloride etching waste liquor | |
| CN112374679A (en) | Treatment method of wastewater generated in cobaltosic oxide preparation process | |
| CN112939295A (en) | Method for preparing acid and alkali by sodium sulfate bipolar membrane electrodialysis | |
| CN111439767A (en) | Efficient preparation method for preparing aluminum sulfate by using waste | |
| CN106430714B (en) | Method for advanced treatment of pesticide wastewater | |
| CN105110515B (en) | A kind of processing method of DSD acid waste water | |
| CN110407236B (en) | Preparation method of electric automobile-grade lithium carbonate | |
| CN111320202A (en) | Deep iron removal method for zinc sulfate solution and preparation method of zinc sulfate | |
| CN108129290B (en) | Method for removing sulfate radical in lactic acid | |
| CN106179241B (en) | A kind of preparation method of the chelating agent of processing heavy metal in waste water | |
| CN1056190C (en) | Citric acid extracting process | |
| CN112759170B (en) | Treatment method of chromium-EDTA-containing wastewater | |
| CN110143868B (en) | Method for removing iron from sodium citrate mother liquor | |
| CN112811442A (en) | Process and system for refining salt by using high-salinity wastewater | |
| CN109607945B (en) | Method for improving biochemical efficiency of wastewater in photovoltaic and electronic industries | |
| CN103073588A (en) | Functional ionic liquid and its application | |
| CN111592190A (en) | Treatment method of carbonate system wastewater | |
| CN111646638A (en) | Method for deep treatment and desalination of sucralose wastewater | |
| CN101624235B (en) | Application of acetobacter aceti for processing copper-containing etching waste solution | |
| CN110404503B (en) | Fluorine-modified hydrotalcite dephosphorization reagent and preparation method and application thereof | |
| CN114272902B (en) | Composite material for removing metallic copper ions in acidic wastewater and preparation method and application thereof | |
| CN219217770U (en) | Treatment device for low-concentration chromium-containing leather wastewater |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210219 |
|
| RJ01 | Rejection of invention patent application after publication |