《Cr2O3制备方法中英文方法.ppt

Primary chromium production Chromium ores Crocoite (PbCrO4) Chromite(FeCr2O4;MgCr2O4) Introduction of Chromium ores Identification of Chromate Minerals Industrial production of Cr2O3（solid-phase synthesis） In the industry fields the general production method is solid-phase reaction by calcining CrO3 . Under the conditions of 700℃ and 90 minutes, when 2% ~ 3% of the combustible powder and the adequate water were added, it showed that the size of Cr2O3 powder was about 200 nm. 以铬酸酐热分解制备 Cr2O3工艺为基础,在可燃性粉末质量分数2%~ 3%、适量水，温度为 700℃，时间为 90 min 的条件下, 可得到平均粒径为 200 nm, 分散性良好的 Cr2O3微粒。 Solid-phase Reaction Process(the reaction principles) Calcining CrO3: Solid-phase Synthesis Process（preparation） CrO3 HCrO4 remove inflammable powder Cr2O3 Industrial production of Cr2O3 （calcining chromium hydroxide） The sodium chromate solution was added sulfur to reduce hexavalent chromium to trivalent chromium，then forming the precipitation of chromium hydroxide. at last generating chromium oxide by calcining chromium hydroxide. 氢氧化铬法：将铬酸钠溶液加入硫磺还原铬酸钠溶液，使铬从六价还原成三价从而形成氢氧化铬沉淀，然后煅烧脱水变成氧化铬。反应式：4Na2CrO4+6S+7H2O=4Cr(OH)3↓+3Na2S2O3+2NaOH 2Cr(OH)3=Cr2O3+3H2O Calcining chromium hydroxide（preparation） 破碎机 laboratory preparation of Cr2O3 Experimental principle：Hydrothermal technique by the reaction system of CrO3 and HCHO in aqueous solution Experimental procedure: 5g CrO3 and 3.5ml HCHO aqueous solution were added into a 200ml Teflon-lined cylindrical bomb previously filled with 120g deionized water, and magnetically stirred for several minutes until they became a homogeneous solution. Then the sealed bomb was heated at 170℃ for 1h in an oven. After that, it was cooled to room temperature and the solution was filtered. The filter cake was washed for 3 times. Then the cake was dried at 100℃ for 5h. The obtained particles were black, with size in the grade of μm to mm. labo