本文選題：偏釩酸鈉　切入點(diǎn)：氫還原法　出處：《河北科技大學(xué)》2015年碩士論文

【摘要】：釩是重要的戰(zhàn)略資源之一,主要應(yīng)用于冶金工業(yè)。釩產(chǎn)品種類繁多,應(yīng)用于各行各業(yè)。本文針對(duì)現(xiàn)行釩冶金沉釩過程產(chǎn)生的含釩鉻高濃度氨氮廢水這一制約釩工業(yè)發(fā)展的關(guān)鍵問題,以沉釩過程前中間體NaVO3為原料,創(chuàng)新性地采用低溫氫還原新工藝制備釩氧化物,取代傳統(tǒng)銨鹽沉釩-偏釩酸銨熱解工藝,避免沉釩廢水的產(chǎn)生,實(shí)現(xiàn)釩氧化物的清潔生產(chǎn)。通過深入研究了NaVO3氫還原過程還原產(chǎn)物價(jià)態(tài)、化學(xué)成分、結(jié)構(gòu)變化規(guī)律,氫還原產(chǎn)物強(qiáng)化水解脫Na及釩價(jià)態(tài)轉(zhuǎn)變行為,以及煅燒過程中溫度、時(shí)間和氣氛對(duì)產(chǎn)物的影響規(guī)律,闡明了還原產(chǎn)物NaVO2的選擇性還原行為,揭示了氧化水解或機(jī)械活化-加壓水解的機(jī)理,實(shí)現(xiàn)了V2O5和V2O3產(chǎn)品的清潔可控制備與含釩NaOH副產(chǎn)物循環(huán)利用。本文主要取得了以下創(chuàng)新性進(jìn)展:1)采用氫氣還原偏釩酸鈉制備NaVO2,系統(tǒng)研究了反應(yīng)溫度(450~700℃)、反應(yīng)時(shí)間(3~4h)、物料厚度(1.5~2cm)等對(duì)還原產(chǎn)物物相及還原轉(zhuǎn)化率的影響。結(jié)果表明,在400℃,NaVO3未被還原,450~700℃時(shí)NaVO3逐步被還原;當(dāng)還原溫度為700℃,還原時(shí)間為3 h,料層厚度為1.5 cm時(shí),可獲得單一的釩物相還原產(chǎn)物NaVO2,且還原率大于92%。2)采用優(yōu)選氫還原條件下所得的還原產(chǎn)物NaVO2進(jìn)行水解實(shí)驗(yàn)研究,主要考察水解溫度、水解時(shí)間、液固比等因素對(duì)還原產(chǎn)物水解脫Na過程的影響。結(jié)果表明,還原產(chǎn)物水解脫鈉進(jìn)而制備出符合要求的中間產(chǎn)物的最優(yōu)工藝條件為:水解溫度為200℃,水解時(shí)間為3 h,液固比為13:1,此條件下Na的脫除率達(dá)到98%,所得中間產(chǎn)物主要由V2O5、V2O3和多釩酸組成,含NaOH溶液可以循環(huán)用于含釩原料焙渣的浸出工藝。3)研究了中間產(chǎn)物煅燒制備釩氧化物的工藝過程,分別考察了煅燒溫度、時(shí)間、氣氛及還原劑類型對(duì)產(chǎn)物的影響。結(jié)果表明,在空氣氣氛下、550℃煅燒3 h,可以得到層狀、平均粒徑小于0.1μm的V2O5產(chǎn)品;在氫氣氣氛下、550℃煅燒3 h,可以得到片狀、平均粒徑D50為70μm的V2O3產(chǎn)品;在氮?dú)鈿夥障隆?50℃草酸還原3 h,可以制備出球形、平均粒徑10μm的V2O3產(chǎn)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，

本文編號(hào)：1693020