CN107760883B - Method for rapidly removing iron from nickel-cobalt solution by using sulfur dioxide and air mixed gas - Google Patents
Method for rapidly removing iron from nickel-cobalt solution by using sulfur dioxide and air mixed gas Download PDFInfo
- Publication number
- CN107760883B CN107760883B CN201710994416.3A CN201710994416A CN107760883B CN 107760883 B CN107760883 B CN 107760883B CN 201710994416 A CN201710994416 A CN 201710994416A CN 107760883 B CN107760883 B CN 107760883B
- Authority
- CN
- China
- Prior art keywords
- solution
- sulfur dioxide
- air
- reactor
- iron
- 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.)
- Active
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B23/00—Obtaining nickel or cobalt
- C22B23/04—Obtaining nickel or cobalt by wet processes
- C22B23/0453—Treatment or purification of solutions, e.g. obtained by leaching
- C22B23/0461—Treatment or purification of solutions, e.g. obtained by leaching by chemical methods
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention discloses a method for rapidly removing iron from a nickel-cobalt solution by using sulfur dioxide and air mixed gas, which comprises the steps of heating the solution containing iron and nickel-cobalt to 25-40 ℃, fully mixing sulfur dioxide and air, then introducing the solution, controlling the pH value in three stages, reacting for 40-45 minutes at the pH value of 0.5-1.5, reacting for 40-45 minutes at the pH value of 1.5-3.0 and reacting for 1.5-2 hours at the pH value of 3.0-4.5, independently introducing air after the reaction to discharge sulfur dioxide, wherein the iron content of the solution after iron removal is less than 0.01g/L, the iron removal rate is more than 99.8%, and the cobalt content of slag is less than 0.5%. The method has the advantages of normal-temperature iron removal, short process flow, high speed, energy consumption and production cost saving, low equipment maintenance cost, and less waste residue discharge and metal loss.
Description
Technical Field
The invention belongs to the field of non-ferrous metal production, and relates to a method for removing iron in nickel and cobalt refining and nickel and cobalt purification processes.
Background
Fe exists in Co, Cu, Ni and Zn ores in the form of impurities, enters a solution along with valuable metals during leaching, and when the valuable metal products are recovered from a leaching solution by an electrodeposition or precipitation process, corresponding purification and iron removal treatment are required. In the electro-cobalt deposition process, the Fe content in the leaching solution reaches 2-5g/L, the Fe content in the electro-deposition solution is generally controlled below 50mg/L, and the Fe content must be strictly controlled below 10mg/L to produce a high-quality cobalt salt product. At present, three methods for removing iron from nickel and cobalt solutions at home and abroad are mainly used, namely yellow sodium iron vitriol iron removal, goethite iron removal and extraction method iron removal. The goethite has the advantages that: the iron content of the solution after iron removal is less than 0.05g/L, the effect is better, and the defects are as follows: the iron removal temperature is between 80 and 90 ℃, the energy consumption is high, the reaction time is long, the iron slag amount is large, and the metal direct recovery rate is low. The extraction method is used for removing iron, fine iron removal is adopted, and the iron content of the solution after iron removal is less than 0.01g/L, so that the defects are that: low efficiency and high cost. The jarosite iron removing and iron removing process adopts a 5-stage continuous precipitation method, the first stage utilizes steam to heat a solution to 85-90 ℃, sodium chlorate is slowly added to oxidize ferrous ions in the solution into ferric ions, sodium carbonate is added from the second stage to the fifth stage, the pH value is respectively adjusted to 2.0, 2.5, 3.0 and 3.5, the reaction time of the solution is about 10 hours, and the total concentration of the iron ions after iron removal is less than 0.05 g/L.
Disclosure of Invention
The invention provides a method for rapidly removing iron from a nickel-cobalt solution by utilizing sulfur dioxide and air mixed gas, aiming at improving the iron removal efficiency of the nickel-cobalt solution, shortening the reaction time, reducing the reaction temperature and reducing the cost.
The technical scheme adopted by the invention is as follows: a method for rapidly removing iron from a nickel-cobalt solution by using sulfur dioxide and air mixed gas comprises the following process conditions:
1) ca (OH) with the mass fraction of 10-20 percent is prepared2Slurry; 2) adding the nickel-cobalt solution to be treated into a reactor, introducing compressed air into the reactor for about 5-10 minutes, and replacing CO in the solution2A gas; 3) heating the solution in the reactor by using direct steam, and controlling the temperature to be between 25 and 40 ℃; 4) adding Ca (OH) to the solution in the reactor2Adjusting the pH value of the solution to 0.5-1.5 by the slurry; introducing mixed gas of sulfur dioxide and air into the solution in the reactor, and reacting for 40-45 minutes; then Ca (OH)2Slurry, adjusting the pH value of the solution in the reactor to 1.5-3.0, and reacting for 40-45 minutes; then Ca (OH)2Slurry, adjusting the pH value of the solution in the reactor to 3.0-4.5, and reacting for 1.5-2 hours; 5) after the reaction is finished, closing the sulfur dioxide gas valve, and introducing compressed air to discharge IIAnd (3) sulfur oxide gas, transferring the solution after reaction to a filter press by using a transfer pump for filtering, sampling and analyzing the filtrate to be qualified, then entering the next procedure, and piling filter residues for treatment. Washing the filter residue, using the washing liquid to dissolve the raw materials, piling the cleaned filter residue and then selling the filter residue.
The further technical scheme is as follows: the solution in the reactor is heated by adopting direct steam, the volume increased by heating is used for making up the volume lost due to the evaporation of introduced mixed gas, and as the heating temperature is lower, the steam consumption is less, the volume expansion of the solution is small, the workload of subsequent procedures is light, and the wastewater discharge is greatly reduced.
The further technical scheme is as follows: the sulfur dioxide and the air are mixed in three stages, firstly, the sulfur dioxide and the air are preliminarily mixed in a header, then the mixture enters a swirler for further mixing, and finally, the sulfur dioxide and the air are fully mixed in a multi-stage bent pipe, and the mixing rate of the sulfur dioxide and the air reaches more than 98 percent.
It is preferable that: the final ratio of the mixed sulfur dioxide and air is 0.8-10:100, and under the condition of the ratio, the consumption of the neutralizing agent and the sulfur dioxide is moderate, and the iron removal efficiency is high.
It is preferable that: the amount of the mixed gas of sulfur dioxide and air introduced into each cubic solution in the reactor is 20m3More than h, high iron removal efficiency.
It is preferable that: returning a part of the iron slag as a seed crystal when the reaction is started initially, and then forming the seed crystal and discharging to form self circulation, namely after the reaction is finished, not completely removing the solution in the reactor, leaving 10% solution, and using the iron slag in the solution as the seed crystal to accelerate the next reaction.
Because the potential required by metal oxidation, the precipitation rate after oxidation and the stability of the produced slag are all closely related to the pH value, the potential required by oxidation is reduced along with the increase of the pH value, the precipitation rate is improved, the more stable the slag form is, and the cobalt content of the slag is increased. Therefore, the pH value needs to be increased as much as possible to improve the iron removal efficiency, but the pH value needs to be reduced to reduce the cobalt content in the slag. Meanwhile, when the pH value is too high, the dissolved sulfur dioxide is increased, part of the sulfur dioxide can play a role in reduction, and Fe3+Reduction to Fe2+Also cause Fe2+The oxidation rate decreases. To solve the problemsThe invention creatively uses three stages of pH value adjustment and control, and the pH value is 0.5-3.0, which is beneficial to Fe2+Oxidation of (2), pH 4.5 favoring Mn2+Oxidation of (2). When the pH value is higher than 4.5, the precipitation amount of Co is obviously increased, and the loss amount is large.
In the iron removal process, the slag obtained after iron removal is a mixture of calcium sulfate and iron slag, and the slag has good filtering performance because the crystal structure of the calcium sulfate is rod-shaped and a bridging structure is formed in the slag; the method can oxidize ferrous iron into ferric iron and form iron slag to be removed, and can also oxidize most of divalent manganese into high-valence manganese to form manganese oxide to be removed.
The invention has the advantages that: (1) the reaction temperature is low, and the raw material solution heat is not required to be heated, so that the energy consumption is obviously saved;
(2) the iron removal time is about 3 hours, and the reaction time is shortened by half compared with that of other modes; the iron removal time is short, after the iron is rapidly removed, the total iron content of the solution is less than 0.01g/L, and the iron removal rate reaches 98.5 percent;
(3) no oxidant is needed to be added in the reaction process, the cost is low, and other impurities are not introduced;
(4) the Fe content of the iron-removed liquid can be stably ensured to be lower than 0.01g/L, and 65% of manganese can be removed, so that the production cost is saved, and the labor amount of downstream processes is reduced;
(5) the amount of slag is small, and the amount of metal contained in the slag is small.
Detailed Description
Example 1
(1) Injecting clear water into the alkali dissolving tank, and adding calcium hydroxide to prepare 10% slurry;
(2) adding dilute alkali liquor into a storage tank at the lower part of the waste gas absorption tower, wherein the height of the dilute alkali liquor is 60% of the height of the storage tank;
(3) adding iron-removing precursor solution into the reactor, wherein the volume of the iron-removing precursor solution is about 35m3；
(4) Introducing compressed air into the reactor for about 10 minutes, and discharging CO in the solution2A gas;
(5) sampling and detecting the liquid before iron removal: co, Fe, Ca;
(6) slowly opening a steam valve, and heating the solution to 30-40 ℃;
(7) slowly adding Ca (OH) to the reactor solution2Adjusting pH value of the solution to 1.0-1.5, opening a valve for sulfur dioxide and air, and introducing mixed gas into the solution in a reactor according to the ratio of sulfur dioxide to air of 3:100, wherein the total amount of the introduced gas is 20m3/h∙m3And reacting the solution for 40 minutes, adjusting the pH value of the solution to 2.0-3.0, reacting for 40 minutes, adjusting the pH value of the solution to 3.5-4.5, reacting for 1.5 hours, closing a sulfur dioxide gas valve at the moment, and stopping introducing sulfur dioxide gas. The sulfur dioxide gas and the air pressure are both more than 2kg/cm2And is convenient to be added into a container.
(8) Continuously introducing compressed air for about 10 minutes, and discharging residual sulfur dioxide in the solution;
(9) and after the reaction is finished, taking 25 liters of solution for precipitation and clarification, taking part of clarified solution for filtering by using filter paper, taking the filtered solution as sample solution for inspection, and inspecting whether the solution is qualified for iron removal. Washing the precipitate as a slag sample, and then inspecting to check the cobalt content of the iron slag;
(10) and (4) after sampling the reaction solution, sending the reaction solution to a filter press for filter pressing, temporarily storing the filtrate in a liquid storage tank, and entering the next procedure after the filtrate is qualified. Drying filter residues in the filter press by using compressed air, then disassembling and bagging, sending to a washing procedure for washing, using washing liquid for dissolving raw materials, piling the cleaned filter residues, and selling the filter residues.
Example 2
(1) Injecting clear water into the alkali dissolving tank, and adding calcium hydroxide to prepare 20% slurry;
(2) adding dilute alkali liquor into a storage tank at the lower part of the waste gas absorption tower, wherein the height of the dilute alkali liquor is 60% of the height of the storage tank;
(3) adding iron-removing precursor solution into the reactor, wherein the volume of the iron-removing precursor solution is about 35m3；
(4) Introducing compressed air into the reactor for about 5 minutes, and discharging CO in the solution2A gas;
(5) sampling and detecting the liquid before iron removal: co, Fe, Ca;
(6) slowly opening a steam valve, and heating the solution to 25-30 ℃;
(7) slowly adding Ca (OH) to the reactor solution2Adjusting pH value of the solution to 0.5-1.0, opening sulfur dioxide and air valve, introducing mixed gas into the solution in the reactor at a ratio of 1:100 of sulfur dioxide to air, wherein total amount of the introduced gas is 20m3/h∙m3And reacting the solution for 45 minutes, adjusting the pH value of the solution to 1.5-2.5, reacting for 45 minutes, adjusting the pH value of the solution to 3.0-4.0, reacting for 2 hours, closing a sulfur dioxide gas valve, and stopping introducing sulfur dioxide gas. The sulfur dioxide gas and the air pressure are both more than 2kg/cm2And is convenient to be added into a container.
(8) Continuously introducing compressed air for about 10 minutes, and discharging residual sulfur dioxide in the solution;
(9) and after the reaction is finished, taking 25 liters of solution for precipitation and clarification, taking part of clarified solution for filtering by using filter paper, taking the filtered solution as sample solution for inspection, and inspecting whether the solution is qualified for iron removal. Washing the precipitate as a slag sample, and then inspecting to check the cobalt content of the iron slag;
(10) and (4) after sampling the reaction solution, sending the reaction solution to a filter press for filter pressing, temporarily storing the filtrate in a liquid storage tank, and entering the next procedure after the filtrate is qualified. Drying filter residues in the filter press by using compressed air, then disassembling and bagging, sending to a washing procedure for washing, using washing liquid for dissolving raw materials, piling the cleaned filter residues, and selling the filter residues.
Claims (5)
1. A method for rapidly removing iron from a nickel-cobalt solution by using sulfur dioxide and air mixed gas comprises the following process conditions:
1) ca (OH) with the mass fraction of 10-20 percent is prepared2Slurry; 2) adding the nickel-cobalt solution to be treated into a reactor, introducing compressed air into the reactor for 5-10 minutes, and replacing CO in the solution2A gas; 3) heating the solution in the reactor, and controlling the temperature to be between 25 and 40 ℃; 4) adding Ca (OH) to the solution in the reactor2Adjusting the pH value of the solution to 0.5-1.5 by the slurry; introducing mixed gas of sulfur dioxide and air into the solution in the reactor, and reacting for 40-45 minutes(ii) a Then Ca (OH)2Slurry, adjusting the pH value of the solution in the reactor to 1.5-3.0, and reacting for 40-45 minutes; then Ca (OH)2Slurry, adjusting the pH value of the solution in the reactor to 3.0-4.5, and reacting for 1.5-2 hours; 5) after the reaction is finished, closing a sulfur dioxide gas valve, introducing compressed air to discharge sulfur dioxide gas, transferring the solution after the reaction to a filtering device for filtering, allowing the filtrate to enter the next procedure, and piling filter residues for treatment; the mixed gas of sulfur dioxide and air is prepared by mixing sulfur dioxide and air in three stages, firstly, preliminarily mixing the sulfur dioxide and air in a header, then, further mixing the sulfur dioxide and air in a swirler, and finally, fully mixing the sulfur dioxide and air in a multistage bent pipe, wherein the mixing rate of the sulfur dioxide and air is more than 98%.
2. The method of claim 1 for rapidly removing iron from nickel cobalt solution by using sulfur dioxide and air mixture, which is characterized in that: the final ratio of the sulfur dioxide to air after mixing is between 0.8-10: 100.
3. The method of claim 1 for rapidly removing iron from nickel cobalt solution by using sulfur dioxide and air mixture, which is characterized in that: the amount of the mixed gas of sulfur dioxide and air introduced into each cubic solution in the reactor is 20m3More than h.
4. The method of claim 1 for rapidly removing iron from nickel cobalt solution by using sulfur dioxide and air mixture, which is characterized in that: after the reaction is completed, the solution in the reactor is not completely removed, 10% solution is left, and the iron slag in the solution is used as a seed crystal to accelerate the next reaction.
5. The method of claim 1 for rapidly removing iron from nickel cobalt solution by using sulfur dioxide and air mixture, which is characterized in that: the solution in the reactor is heated by direct steam.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710994416.3A CN107760883B (en) | 2017-10-23 | 2017-10-23 | Method for rapidly removing iron from nickel-cobalt solution by using sulfur dioxide and air mixed gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710994416.3A CN107760883B (en) | 2017-10-23 | 2017-10-23 | Method for rapidly removing iron from nickel-cobalt solution by using sulfur dioxide and air mixed gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107760883A CN107760883A (en) | 2018-03-06 |
| CN107760883B true CN107760883B (en) | 2020-01-17 |
Family
ID=61269186
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710994416.3A Active CN107760883B (en) | 2017-10-23 | 2017-10-23 | Method for rapidly removing iron from nickel-cobalt solution by using sulfur dioxide and air mixed gas |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107760883B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109607604B (en) * | 2018-12-14 | 2021-09-14 | 攀枝花东方钛业有限公司 | Metatitanic acid bleaching system and method |
| CN111847528B (en) * | 2020-06-10 | 2022-10-11 | 包头昊明稀土新电源科技有限公司 | Method for removing iron in waste nickel-hydrogen battery |
| CN113388742A (en) * | 2021-05-31 | 2021-09-14 | 浙江中金格派锂电产业股份有限公司 | Method for continuously removing iron from leached liquid of cobalt intermediate product |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003054238A1 (en) * | 2001-12-21 | 2003-07-03 | Congo Mineral Developments Ltd | A method for the recovery of cobalt |
| CN101333604A (en) * | 2008-08-01 | 2008-12-31 | 湖南阳光电化有限公司 | Deironing agent of low grade natural manganese dioxide ore for manganese leaching liquid and deironing process |
| CN102264925A (en) * | 2008-11-24 | 2011-11-30 | Bhp比利顿奥林匹克坝有限公司 | Process for controlled oxidation of a ferrous solution |
| CN102634662A (en) * | 2012-04-26 | 2012-08-15 | 浙江华友钴业股份有限公司 | Method for low-temperature deironing by using mixed gas of air and sulfur dioxide (SO2) |
| CN103924082A (en) * | 2014-04-28 | 2014-07-16 | 北京矿冶研究总院 | Method for removing iron from laterite-nickel ore high-pressure leaching solution |
| JP2016191129A (en) * | 2015-03-31 | 2016-11-10 | Ｊｘ金属株式会社 | Method for removing iron and collecting valuable metals from iron-containing solution |
| CN106756022A (en) * | 2016-11-29 | 2017-05-31 | 金川集团股份有限公司 | A kind of two sections of low temperature method for removing iron of copper-cobalt mine leachate |
-
2017
- 2017-10-23 CN CN201710994416.3A patent/CN107760883B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003054238A1 (en) * | 2001-12-21 | 2003-07-03 | Congo Mineral Developments Ltd | A method for the recovery of cobalt |
| CN101333604A (en) * | 2008-08-01 | 2008-12-31 | 湖南阳光电化有限公司 | Deironing agent of low grade natural manganese dioxide ore for manganese leaching liquid and deironing process |
| CN102264925A (en) * | 2008-11-24 | 2011-11-30 | Bhp比利顿奥林匹克坝有限公司 | Process for controlled oxidation of a ferrous solution |
| CN102634662A (en) * | 2012-04-26 | 2012-08-15 | 浙江华友钴业股份有限公司 | Method for low-temperature deironing by using mixed gas of air and sulfur dioxide (SO2) |
| CN103924082A (en) * | 2014-04-28 | 2014-07-16 | 北京矿冶研究总院 | Method for removing iron from laterite-nickel ore high-pressure leaching solution |
| JP2016191129A (en) * | 2015-03-31 | 2016-11-10 | Ｊｘ金属株式会社 | Method for removing iron and collecting valuable metals from iron-containing solution |
| CN106756022A (en) * | 2016-11-29 | 2017-05-31 | 金川集团股份有限公司 | A kind of two sections of low temperature method for removing iron of copper-cobalt mine leachate |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107760883A (en) | 2018-03-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107760883B (en) | Method for rapidly removing iron from nickel-cobalt solution by using sulfur dioxide and air mixed gas | |
| CN112662877B (en) | Method for preparing high-purity nickel sulfate from electrolytic manganese sulfide slag | |
| CN105060599B (en) | A kind of stainless steel acid cleaning waste water resource recycle method | |
| KR20020070275A (en) | Method for leaching nickeliferous laterite ores | |
| CN102070198A (en) | Method for preparing high-purity manganese sulfate and high-purity manganese carbonate by reduction leaching of pyrolusite through scrap iron | |
| CN108821255B (en) | Preparation method of iron phosphate | |
| CN102627313A (en) | Wet production process for feed-grade active zinc oxide | |
| WO2023036053A1 (en) | Cooperative treatment method and treatment system for high-salt solid waste ash and acidic wastewater of steel plant | |
| CN103253710A (en) | Process for producing sodium chromate from chromite through dissolution in acid and oxidization | |
| CN111056576A (en) | Method for preparing battery-grade cobalt sulfate from low-grade cobalt-sulfur tailings | |
| CN111826523B (en) | Method for refining nickel hydroxide cobalt | |
| CN112410561A (en) | Treatment method for neutralizing gypsum slag in vanadium precipitation wastewater | |
| CN111500862A (en) | Method for removing iron and aluminum from mixed nickel cobalt hydroxide leachate | |
| CN110317962A (en) | Manganese Wet-smelting method and manganese hydrometallurgy system | |
| CN106868304A (en) | A kind of method for reducing impurity content in zinc hydrometallurgy oxidation scum | |
| WO2016194709A1 (en) | Free acid-removing equipment, free acid-removing method, and method for manufacturing mixed nickel and cobalt sulfide | |
| DE1812332B2 (en) | PROCESS FOR FELLING MANGANE, IRON AND / OR COBALT FROM SOLUTIONS THEREOF | |
| CN108441649B (en) | Method for extracting nickel from chemical precipitation nickel sulfide material | |
| CN111320202A (en) | Deep iron removal method for zinc sulfate solution and preparation method of zinc sulfate | |
| CN104591291A (en) | Method for producing manganese sulfate by performing zinc electrodeposit anode slime treatment on sulfur dioxide flue gas | |
| CN107760867A (en) | The method for preparing mixed rare earth carbonate with mixed precipitant under sulfuric acid system | |
| CN108996752B (en) | Method for recovering low-concentration nickel from nickel extraction waste water | |
| CN208856921U (en) | A kind of production line of nickelous carbonate | |
| WO2019127305A1 (en) | Processing method for producing sodium sulfite product by so2 flue gas absorption and arsenic-removal purification using leaching solution of arsenic-containing industrial alkaline residue | |
| CN110790292A (en) | Method for removing sulfide in Bayer process crude liquor through oxidation |
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 | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |