CN1394974A - Method for purifying chromium - Google Patents
Method for purifying chromium Download PDFInfo
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- CN1394974A CN1394974A CN02121236A CN02121236A CN1394974A CN 1394974 A CN1394974 A CN 1394974A CN 02121236 A CN02121236 A CN 02121236A CN 02121236 A CN02121236 A CN 02121236A CN 1394974 A CN1394974 A CN 1394974A
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Abstract
The purification method of metal chromium is characterized by that under the condition of a certain pressure the chromium powder is press-formed, the graphite powder and plant gum are added in the metal chromium powder, and said purification emthod is implemented under the condition of vacuum at 1410-1450 deg.C for 6-8 hr. and the oxygen, carbon, sulfur and nitrogen impurity content being in purified metal chromium is greatly reduced, and said invented metal chlomium can be used in the metallurgical and electronic industries, etc.
Description
Technical Field
The invention relates to a method for purifying metallic chromium produced by aluminothermic processes. The method can reduce the contents of impurities of carbon (C), nitrogen (N), oxygen (O) and sulfur (S) in the metallic chromium material.
Background
Chromium is one of important alloy elements and is widely applied to industrial production, such as production of precision alloys, resistance alloys, high-temperature alloys, electroplated metal parts, steel and the like. In recent years, the method is also used in the high-tech fields of aviation, aerospace and the like.
Chromium exists in nature mainly in the form of chromite, and its composition is FeO-Cr2O3Or FeCrO. The chromium ore resources in China are relatively poor and mainly depend on import. Currently, metallic chromium can be produced by electrolytic, aluminothermic or other pyrometallurgical methods. The metallic chromium prepared by the electrolysis method is plate-shaped, and the impurity content is 0.006% of C, 0.5% of O, 0.03% of N and 0.03% of S (weight percentage); the chromium metal produced by the aluminothermic process is in the form of a cake and can be ground to a smaller size, typically with impurity levels of 0.03% C, 0.5%O, 0.05% N, 0.02% S (by weight).
Because of the very strict requirements for the content of gasified impurities in the metallic chromium in metallurgical applications, the metallic chromium produced by the thermite process in the prior art cannot meet the requirements of the advanced technical field. The chromium metal needs to be refined to reduce the content of these impurities to less than 0.01% C, 0.03% O, 0.002% N, 0.004% S (weight percent).
US-4504310A discloses a method for purifying metallic chromium, which uses chromium prepared by an aluminothermic method as a raw material, uses chromium oxide and aluminum as raw materials in the process of preparing by the aluminothermic method, uses potassium dichromate as a heat generating agent, firstly grinds the chromium in the process of purifying the chromium, then uses a traditional method for forming, uses phenolic resin as a binding agent, dries at the temperature of 200-230 ℃, and finally carries out vacuum sintering at the sintering temperature of 1100-1400 ℃. But the product still contained 0.04 wt.% oxygen.
U.S. Pat. No. 4, 5092921,78 also discloses a process for purifying metallic chromium, wherein chromium oxide, aluminum powder, carbon powder and an easily-sulfidable metal powder are mixed and sintered at 1300 ℃, wherein the easily-sulfidable metal powder can be selected from Ni, Cu, Sn or Hg, and is protected by vacuum atmosphere or inert gas. It can be seen that in this process, it is necessary to mix multiple powders uniformly and also to add metal powders.
CN-1311723A discloses a method for purifying metallic chromium by a two-step method, which comprises treating metallic chromium with hydrogen at 1600 ℃ for 2-10h, then treating metallic chromium under 15Pa or less and at 1600 ℃ for 2-60h under vacuum, and finally cooling to recover the purified metallic chromium. Therefore, the production cost is greatly increased due to the addition of the hydrogen treatment process step.
The invention overcomes the defects of the invention, and the metallic chromium prepared by the thermit method is added with a special reagent for molding, and then is sintered in vacuum at high temperature, and the impurity content of the obtained product is 0.01 percent of C, 0.03 percent of O, 0.002-0.0005 percent of N and 0.004 percent of S (weight percentage).
Disclosure of Invention
A method for purifying chromium metal, comprising the steps of:
adopting an aluminothermic method to produce metal chromium, and taking potassium chlorate as a heating agent;
grinding chromium metal, adding a small amount of 3-5 μm graphite powder and vegetable gum aqueous solution, mixing, molding, and oven drying;
putting the dried chromium blocks into a sintering furnace, vacuumizing, and treating at 1410-1450 ℃ for 6-8 h;
cooling and recovering the purified chromium metal.
Among them, metallic chromium is preferably ground to 60 mesh or less.
The addition amount of the vegetable gum is 0.05 percent of the weight of the metal chromium.
The vacuum sintering temperature is preferably 1410-1430 deg.C, and most preferably 1415 deg.C.
The degree of vacuum is preferably 2X 10-2Pa to 3X 10-2Pa。
The forming pressure is preferably 30MPa, and the formed compact has a cylindrical shape with a diameter of less than or equal to phi 25X 18 mm.
The temperature is reduced to 200 ℃ under vacuum.
Firstly, when producing metal chromium by thermit method, selecting chromium oxide and aluminium granules with low impurity content, and using potassium chlorate as heat-generating agent. The nitrogen and oxygen in the metal chromium are mainly present in the form of compounds, for example, enough nitrogen is enough to CrN and Cr2N, oxygen is Cr2O3、Al2O3There, the reduction of nitrogen in metallic chromium is achieved by decomposition of the nitride at elevated temperatures.
Oxide removal can be achieved only by adding a reducing agent at a high temperature. The reduction product can escape, cannot pollute the chromium metal, and only carbon can be selected as the reducing agent.
The temperature must be increased to accelerate the nitrogen and oxygen removal reactions. The partial pressure of system N, CO was reduced, i.e., the vacuum was increased.
Detailed description of the preferred embodimentexample 1
Selecting chromium oxide and aluminum particles with low impurity content, taking potassium chlorate as a heating agent, and drying the materials without moisture, wherein the granularity of each material is proper. The ingredient calculation should be accurate, the aluminum adding amount is 92-93% of theoretical amount, and the material mixing is uniform. Discharging most of slag 10 minutes after the smelting reaction is finished. After the chromium metal and the ingot are cooled for 24hours, slag is separated, and the metal ingot is thrown out of steel shots by a shot blasting machine to clean the surface of the chromium ingot, so that the surface has no oxide film and visible inclusions.
Smashing the cleaned metal ingot, and grinding the metal ingot to below 60 meshes by using ball milling equipment for later use. Adding 3-5 μm graphite powder with theoretical amount of 95% and aqueous solution of vegetable gum, and mixing. After confirming that the materials are uniform, pressing the materials into cylindrical chromium blocks with the diameter of 25 multiplied by 18mm by using the pressure of 30 MPa. The chromium blocks are thoroughly dried at 200 ℃ for 3-4 hours.
Putting the dried chromium blocks into a vacuum sintering furnace, and vacuumizing to 10 DEG-2Pa grade, heating, at 1415 deg.C and vacuum degree of 3 × 10-2The treatment is carried out for 6 to 8 hours under the Pa condition, and the treatment time is short and economic although chromium is volatilized and lost.
And cooling the chromium metal in the vacuum sintering furnace to 200 ℃ under a vacuum condition, and discharging the chromium metal from the furnace to finish the purification task.
The purified metal C is less than 0.01 percent, O is less than 0.03 percent, N is less than 0.002 to 0.0005 percent, S is less than 0.004 percent, and Cr is more than 99.4 percent.
Claims (11)
1. A method for purifying chromium metal, comprising the steps of:
adopting an aluminothermic method to produce metal chromium, and taking potassium chlorate as a heating agent;
grinding chromium metal, adding a small amount of 3-5 μm graphite powder and vegetable gum aqueous solution, mixing, molding, and oven drying;
putting the dried chromium blocks into a sintering furnace, vacuumizing, and treating at 1410-1450 ℃ for 6-8 h;
cooling and recovering the purified chromium metal.
2. The method of claim 1, wherein the chromium metal is ground to below 60 mesh.
3. The process of claim 1 or 2, wherein the vegetable gum is added in an amount of 0.05% by weight of the chromium metal.
4. The method of claim 1 or 2, wherein the vacuum sintering temperature is 1410-1430 ℃.
5. The method of claim 4, wherein the vacuum sintering temperature is 1415 ℃.
6. The method of claim 1, wherein the degree of vacuum pumping is 2 x 10-2Pa to 3X 10-2Pa。
7. The process of claim 1 or 2, wherein the forming pressure is 30 MPa.
8. The method of claim 7 wherein the chromium metal has a cylindrical shape of less than or equal to Φ 25 x 18 mm.
9. The method of claim 1, wherein the cooling is to 200 ℃ under vacuum.
10. Chromium metal obtainable by the process of any one of claims 1 to 9.
11. The chromium metal of claim 10, wherein the chromium metal has an impurity level of 0.01% C, 0.03% O, 0.002% to 0.0005% N, 0.004% S.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021212368A CN1176233C (en) | 2002-06-11 | 2002-06-11 | Method for purifying chromium |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021212368A CN1176233C (en) | 2002-06-11 | 2002-06-11 | Method for purifying chromium |
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| CN1394974A true CN1394974A (en) | 2003-02-05 |
| CN1176233C CN1176233C (en) | 2004-11-17 |
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| CNB021212368A Expired - Fee Related CN1176233C (en) | 2002-06-11 | 2002-06-11 | Method for purifying chromium |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102899511A (en) * | 2012-10-31 | 2013-01-30 | 中信锦州金属股份有限公司 | Method for smelting high-purity metal chromium by external furnace method |
| CN102965526A (en) * | 2012-11-19 | 2013-03-13 | 锦州新桥高纯材料有限公司 | Method for producing high-purity metal chromium by using carbon reduction method |
| WO2016110739A3 (en) * | 2014-11-05 | 2016-09-01 | Cbmm-Companhia Brasileira De Metalurgia E Mineração | Processes for producing low nitrogen metallic chromium and chromium-containing alloys and the resulting products |
| CN107109542A (en) * | 2014-11-05 | 2017-08-29 | 巴西冶金采矿公司 | For producing low nitrogen, the method for the chromium substantially free of nitride and the nickel-base alloy containing chromium plus niobium and gained chromium and nickel-base alloy |
| CN112795794A (en) * | 2021-04-06 | 2021-05-14 | 西安斯瑞先进铜合金科技有限公司 | Method for preparing high-purity metal chromium block by adopting wet-process mixed metal powder |
-
2002
- 2002-06-11 CN CNB021212368A patent/CN1176233C/en not_active Expired - Fee Related
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102899511A (en) * | 2012-10-31 | 2013-01-30 | 中信锦州金属股份有限公司 | Method for smelting high-purity metal chromium by external furnace method |
| CN102899511B (en) * | 2012-10-31 | 2014-01-29 | 中信锦州金属股份有限公司 | Method for smelting high-purity metal chromium by external furnace method |
| CN102965526A (en) * | 2012-11-19 | 2013-03-13 | 锦州新桥高纯材料有限公司 | Method for producing high-purity metal chromium by using carbon reduction method |
| CN102965526B (en) * | 2012-11-19 | 2014-07-02 | 锦州新桥高纯材料有限公司 | Method for producing high-purity metal chromium by using carbon reduction method |
| CN107109542A (en) * | 2014-11-05 | 2017-08-29 | 巴西冶金采矿公司 | For producing low nitrogen, the method for the chromium substantially free of nitride and the nickel-base alloy containing chromium plus niobium and gained chromium and nickel-base alloy |
| CN107002170A (en) * | 2014-11-05 | 2017-08-01 | 巴西冶金采矿公司 | Method and products obtained therefrom for producing low nitrogen crome metal and chrome-bearing alloy |
| WO2016110739A3 (en) * | 2014-11-05 | 2016-09-01 | Cbmm-Companhia Brasileira De Metalurgia E Mineração | Processes for producing low nitrogen metallic chromium and chromium-containing alloys and the resulting products |
| US9771634B2 (en) | 2014-11-05 | 2017-09-26 | Companhia Brasileira De Metalurgia E Mineração | Processes for producing low nitrogen essentially nitride-free chromium and chromium plus niobium-containing nickel-based alloys and the resulting chromium and nickel-based alloys |
| US10041146B2 (en) | 2014-11-05 | 2018-08-07 | Companhia Brasileira de Metalurgia e Mineraçäo | Processes for producing low nitrogen metallic chromium and chromium-containing alloys and the resulting products |
| CN109913651A (en) * | 2014-11-05 | 2019-06-21 | 巴西冶金采矿公司 | Method and gained chromium and nickel-base alloy for producing low nitrogen, being substantially free of the chromium of nitride and add the nickel-base alloy of niobium containing chromium |
| US11124861B2 (en) | 2014-11-05 | 2021-09-21 | Companhia Brasileira De Metalurgia E Mineração | Processes for producing low nitrogen essentially nitride-free chromium and chromium plus niobium-containing nickel-based alloys and the resulting chromium and nickel-based alloys |
| CN109913651B (en) * | 2014-11-05 | 2022-01-14 | 巴西冶金采矿公司 | Method for producing low-nitrogen, essentially nitride-free chromium and chromium plus niobium-containing nickel-based alloys and resulting chromium and nickel-based alloys |
| US11230751B2 (en) | 2014-11-05 | 2022-01-25 | Companhia Brasileira De Metalurgia E Mineracão | Processes for producing low nitrogen metallic chromium and chromium-containing alloys and the resulting products |
| CN112795794A (en) * | 2021-04-06 | 2021-05-14 | 西安斯瑞先进铜合金科技有限公司 | Method for preparing high-purity metal chromium block by adopting wet-process mixed metal powder |
| CN112795794B (en) * | 2021-04-06 | 2021-07-06 | 西安斯瑞先进铜合金科技有限公司 | Method for preparing high-purity metal chromium block by adopting wet-process mixed metal powder |
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| Publication number | Publication date |
|---|---|
| CN1176233C (en) | 2004-11-17 |
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