(中南大學(xué) 冶金科學(xué)與工程學(xué)院 ， 長(zhǎng)沙 410083)
摘 要: 拜耳法生產(chǎn)氧化鋁的過(guò)程中， 堿耗的主要原因是因?yàn)橛锈c硅渣的生成， 堿耗可以用赤泥鈉硅比(N/S)表征。 通過(guò)對(duì)鈉硅渣和水化石榴石反應(yīng)行為的熱力學(xué)分析， 發(fā)現(xiàn)高飽和系數(shù)(x＞1)的水化石榴石不易被苛性堿分解， 低飽和系數(shù)的水化石榴石易被分解而轉(zhuǎn)化為鈉硅渣， 且鈉硅渣也可以轉(zhuǎn)化為水化石榴石， 而在Na2CO3溶液中， 任何形式的水化石榴石均能被分解生成鈉硅渣。 實(shí)驗(yàn)研究結(jié)果表明， 不同礦區(qū)的鋁土礦對(duì)赤泥N/S影響不明顯， 母液中Na2CO3濃度升高、 石灰加入量降低、 母液中堿濃度降低均會(huì)導(dǎo)致赤泥N/S升高， 引起堿耗增大。 因此, 降低母液中Na2CO3濃度、 提高石灰添加量將明顯有利于赤泥N/S的降低。
關(guān)鍵字: 鈉硅渣; 水化石榴石; 堿耗; N/S; 碳酸鈉
ZHOU Qiu-sheng, XU Hua-jun
（ School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract: In the process of alumina production by Bayer process, the loss of soda is mainly caused by the formation of sodium hydrate alumino-silicate. Based on the thermodynamic analysis of the reaction law between sodium hydrate alumino-silicate and hydrogarnet, it is found that hydrogarnet with more amount of SiO2 (x＞1) can not be decomposed by caustic solution easily, while hydrogarnet with x＜0.5 can be decomposed into sodium hydrate alumino-silicate, and sodium hydrate alumino-silicate can also be transformed into hydrogarnet with the addition of CaO. But in sodium carbonate solution, any form of hydrogarnet can be decomposed into sodium hydrate alumino-silicate. Experimental results show that bauxite in different areas has little influence on the loss of soda, while more concentration of Na2CO3 or lower concentration of Na2O in spent solution, or worse quality of limes will enhance N/S in red mud, and cause more loss of soda. Therefore, decreasing the concentration of Na2CO3 or obtaining better quality of limes will reduce N/S.
Key words: sodium hydrate alumino-silicate; hydrogarnet; loss of soda; mass ratio of Na2O/SiO2; sodium carbonate
