真空熱還原法煉鎂技術(shù)
(東北大學(xué) 材料與冶金學(xué)院，沈陽 110004)
摘 要: 提出一種以白云石和菱鎂石的混合礦物為原料、以鋁粉為還原劑的真空熱還原煉鎂，然后利用鎂還原后的殘渣制取氫氧化鋁的工藝和技術(shù)，并進(jìn)行實驗研究。結(jié)果表明：以煅燒后的白云石和菱鎂石混合礦物為原料的真空金屬熱還原煉鎂，在還原溫度為1 200 ℃、還原時間為2 h、鋁粉過量系數(shù)為5%的條件下，鎂的還原率可達(dá)89%以上，還原渣主要物相為CaO·2Al2O3，還原渣中Al2O3的含量為67%左右；該煉鎂還原渣經(jīng)碳酸鈉和氫氧化鈉的混合堿液浸出后，Al2O3的浸出率達(dá)到85%，浸出Al2O3后渣的主要成分為CaCO3；浸出液中的Al2O3以可溶解的鋁酸鈉存在于浸出液中，后經(jīng)碳分分解制得氫氧化鋁，氫氧化鋁的白度達(dá)到97%。
關(guān)鍵字: 鋁熱還原；鋁酸鈣；氧化鋁；鎂；菱鎂石；白云石；真空熱還原；浸出
（School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China）
Abstract:The experiments of a new method of producing magnesium and aluminum hydroxide as by-product using dolomite and magnesite as materials and aluminum powder as reductant were studied. The results show that when magnesium is produced by vacuum aluminothermic reduction using the mixture of calcined dolomite and calcined magnesite as materials, the reduction ratio of Mg can be over 89% under the conditions of reduction temperature 1 200 ℃, reduction time 2 h, and the excess coefficient of reductant 5%. The main phase of the reduction slag is CaO·2Al2O3 and the content of alumina is about 67%. The Al2O3 leaching rate of reduction slag reaches 85% when the reduction slag is leached with a mixture of sodium hydroxide and sodium carbonate. The main phase of leaching slag is CaCO3. The Al2O3 enters into the leaching solution with soluble sodium aluminate. Aluminum hydroxide with whiteness of over 97% can be obtained after carbonation precipitation.
Key words: aluminothermic reduction; calcium aluminate; aluminum oxide; magnesium; dolomite; magnesite; vacuum thermal reduction; leaching
