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Method for recycling vanadium pentoxide and sodium dichromate
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A technology of vanadium pentoxide and sodium dichromate, applied in the field of chromium salt
Active Publication Date: 2011-04-20
GANSU JINSHI CHEM
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And the existence of sodium vanadate has a serious impact on the product quality of sodium dichromate processed by alkaline solution
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Embodiment 1
[0033] Embodiment 1: reclaim sodium dichromate,
[0034] Take 1.8 kg of vanadium-containing, chromium-calcium slag (Na 2 Cr 2 o 7 .2H 2 O: 13%, V 2 o 5 : 1.63% CaO: 28%), add 1.8 kg of water, beating and stirring evenly, then add 0.36 kg of soda ash, stir and leach at 80°C for 2 hours. Filter calcium carbonate slag, in alkaline solution (Na 2 Cr 2 o 7 .2H 2 O: 148g / L, V 2 o 5 : 15g / L) Slowly add sulfuric acid to adjust PH = 1.2, heat and mature at 90°C for 1 hour, filter and wash the sodium polyvanadate precipitate (V 2 o 5 : 53%, Na 2 Cr 2 o 7 .2H 2 O: 2.8%); acidic sodium dichromate solution (PH=1.2, V 2 o 5 : 0.45g / L, Na 2 Cr 2 o 7 .2H 2 O: 124g / L) into the sodium dichromate production line to produce sodium dichromate.
Embodiment 2
[0035] Embodiment 2: reclaim vanadium pentoxide,
[0036] Get the sodium polyvanadate precipitation of embodiment 1 filtration, wash and be 4% industrial sodium hydroxide heating and dissolving with 600ml concentration and adjust PH=8, filter to remove impurity, add sulfuric acid 1ml in the vanadium-rich liquid, adjust PH to be 2, Add 36 grams of industrial ammonium sulfate, stir at 50°C for 0.8 hours, filter and precipitate ammonium polyvanadate, wash with 600ml of ammonium sulfate with a concentration of 3% for 4 times on average, and the hexavalent chromium in the last washing solution is 0.6g / L. The ammonium polyvanadate precipitate is dried at 105-110°C for 2 hours, put into a resistance furnace and roasted at 550°C for 2 hours to produce vanadium pentoxide with a content of 99.68%.
Embodiment 3
[0038] Take 1.5 kg of vanadium-containing calcium slag (Na 2 Cr 2 o 7 .2H 2 O: 12%, V 2 o 5 : 1.5% CaO: 30%), add 1.5 kg of water, beating and stirring evenly, then add 0.15 kg of soda ash, stir and leach at 85°C for 3 hours, and filter the calcium carbonate residue. Its alkaline solution (Na 2 Cr 2 o 7 .2H 2 O: 136.8g / L, V 2 o 5 : 16.8g / L) with sulfuric acid to adjust PH=2.5, 90 ℃ heat preservation and aging for 3 hours, filter and wash the sodium polyvanadate precipitate (V 2 o 5 : 59.28%, Na 2 Cr 2 o 7 .2H 2 O: 2.5%); acidic sodium dichromate solution (PH=2.5, V 2 o 5 : 0.80g / L, Na 2 Cr 2 o 7 .2H 2O: 130g / L) to produce sodium dichromate. Heat and dissolve sodium polyvanadate with 250ml of 7% sodium hydroxide, adjust the pH to 9, and filter to remove impurities. Add 0.8ml of sulfuric acid to the vanadium-enriched liquid, adjust PH=2.5, add 39.2 grams of industrial ammonium sulfate, stir at 60°C for 0.5 hours, filter, and wash the resulting ammonium po...
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Abstract
The invention discloses a method for recycling vanadium pentoxide and sodium dichromate, which utilizes the discharged wastes, i.e. vanadium-containing and chromium-calcium-containing slag in the process for producing sodium dichromate as raw materials. The method comprises the following steps: pulping the raw materials by using water and adding pure alkali into the mixture; dissolving out pentavalent vanadium and hexavalent chromium in the slag; filtering calcium carbonate residues; acidifying an alkali solution by using sulphuric acid; keeping the temperature and curing; filtering and precipitating; enabling the acid liquid enriched in hexavalent chromium to enter the procedure for producing the sodium dichromate to produce the sodium dichromate; heating and dissolving sodium polyoxovanadate by using a sodium hydroxide solution and regulating the pH value; filtering and removing impurities; adding sulphuric acid into a rich vanadium liquid to acidify until the pH value is between about 4 and 5; adding an ammonium salt; and regulating the pH value to 2-2.5 by using the sulphuric acid; crystallizing the poly-vanadium acid ammonium to precipitate under the condition of heating and stirring; and filtering, washing and baking to prepare the qualified finished product of vanadium pentoxide. The method can be used for realizing the cleaning production in the chromium salt industry.
Description
technical field [0001] The invention belongs to the field of chromium salts, and is a technology for recycling and reusing the wastes generated in the process of "producing sodium dichromate"---the slag containing vanadium and chromium-calcium. Background technique [0002] The waste discharged in the process of "production of sodium dichromate" --- the stacking of vanadium-containing and chromium-calcium slag is a major environmental protection problem for the chromium salt industry, and its comprehensive development and utilization face technical problems. [0003] In the production process of "production of sodium dichromate process", because chromite contains vanadium trioxide, it is converted into water-soluble sodium vanadate under the condition of high-temperature alkaline roasting in the rotary kiln, and enters the alkaline solution during leaching, resulting in The vanadium pentoxide content in the alkaline solution reaches 300-900ppm. And the existence of sodium v...
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