偏钒酸钠氢还原制备钒氧化物新工艺研究

发布时间：2018-03-31 23:39

  本文选题：偏钒酸钠　切入点：氢还原法　出处：《河北科技大学》2015年硕士论文

【摘要】：钒是重要的战略资源之一,主要应用于冶金工业。钒产品种类繁多,应用于各行各业。本文针对现行钒冶金沉钒过程产生的含钒铬高浓度氨氮废水这一制约钒工业发展的关键问题,以沉钒过程前中间体NaVO3为原料,创新性地采用低温氢还原新工艺制备钒氧化物,取代传统铵盐沉钒-偏钒酸铵热解工艺,避免沉钒废水的产生,实现钒氧化物的清洁生产。通过深入研究了NaVO3氢还原过程还原产物价态、化学成分、结构变化规律,氢还原产物强化水解脱Na及钒价态转变行为,以及煅烧过程中温度、时间和气氛对产物的影响规律,阐明了还原产物NaVO2的选择性还原行为,揭示了氧化水解或机械活化-加压水解的机理,实现了V2O5和V2O3产品的清洁可控制备与含钒NaOH副产物循环利用。本文主要取得了以下创新性进展:1)采用氢气还原偏钒酸钠制备NaVO2,系统研究了反应温度(450~700℃)、反应时间(3~4h)、物料厚度(1.5~2cm)等对还原产物物相及还原转化率的影响。结果表明,在400℃,NaVO3未被还原,450~700℃时NaVO3逐步被还原;当还原温度为700℃,还原时间为3 h,料层厚度为1.5 cm时,可获得单一的钒物相还原产物NaVO2,且还原率大于92%。2)采用优选氢还原条件下所得的还原产物NaVO2进行水解实验研究,主要考察水解温度、水解时间、液固比等因素对还原产物水解脱Na过程的影响。结果表明,还原产物水解脱钠进而制备出符合要求的中间产物的最优工艺条件为:水解温度为200℃,水解时间为3 h,液固比为13:1,此条件下Na的脱除率达到98%,所得中间产物主要由V2O5、V2O3和多钒酸组成,含NaOH溶液可以循环用于含钒原料焙渣的浸出工艺。3)研究了中间产物煅烧制备钒氧化物的工艺过程,分别考察了煅烧温度、时间、气氛及还原剂类型对产物的影响。结果表明,在空气气氛下、550℃煅烧3 h,可以得到层状、平均粒径小于0.1μm的V2O5产品;在氢气气氛下、550℃煅烧3 h,可以得到片状、平均粒径D50为70μm的V2O3产品;在氮气气氛下、550℃草酸还原3 h,可以制备出球形、平均粒径10μm的V2O3产品。
[Abstract]:Vanadium is one of the important strategic resources, mainly used in metallurgical industry. This paper aims at the key problem which restricts the development of vanadium industry, which is the high concentration ammonia nitrogen wastewater produced by vanadium metallurgy and vanadium precipitation process. The intermediate NaVO3 before vanadium precipitation process is used as raw material. Vanadium oxide was prepared by a new process of hydrogen reduction at low temperature, which replaced the traditional pyrolysis process of ammonium salt precipitation vanadium and ammonium metavanadate, thus avoiding the production of vanadium precipitation wastewater. In order to realize the clean production of vanadium oxide, the valence state, chemical composition, structure change of NaVO3 hydrogen reduction product, the behavior of strengthening water deoxidizing Na and vanadium valence state of hydrogen reduction product, and the temperature during calcination were studied. The effects of time and atmosphere on the product were discussed. The selective reduction behavior of the reductive product NaVO2 was clarified, and the mechanism of oxidative hydrolysis or mechanical activation-pressure hydrolysis was revealed. Clean and controllable preparation of V2O5 and V2O3 products and recycling of vanadium containing NaOH by-products have been realized. In this paper, the following innovative progress has been made: 1) NaVO _ 2 is prepared by hydrogen reduction of sodium metavanadate. The reaction temperature is 450 ~ 700 鈩，

本文编号：1693020