(中南大學(xué) 冶金與環(huán)境學(xué)院 長沙410083)
摘 要: 活性晶種可以強化鋁酸鈉溶液晶種分解并顯著提高種分分解率。通過碳酸氫鈉誘導(dǎo)鋁酸鈉溶液快速分解制備活性晶種，研究其性質(zhì)及對種分過程的影響規(guī)律，探討活性晶種強化種分過程的機理。結(jié)果表明：碳酸氫鈉誘導(dǎo)鋁酸鈉溶液快速分解制備的活性晶種主要是拜耳石型氫氧化鋁，其粒度細、比表面積大、表面能高且表面溶劑化趨勢較強，具有很強的促進鋁酸鈉溶液分解的能力，在晶種添加量僅為1 g/L的條件下，鋁酸鈉溶液種分分解率可達65%以上。晶種強化鋁酸鈉溶液種分的能力除了隨晶種表面積的增大而增強外，還隨晶種表面溶劑化趨勢的增強和晶種表面Zeta電位的升高而增強。在晶種分解初期，活性晶種誘導(dǎo)鋁酸鈉溶液中其他鋁酸根陰離子向 轉(zhuǎn)變，其誘導(dǎo)溶液結(jié)構(gòu)變化的能力隨晶種表面積的增大和晶種表面溶劑化趨勢的增強而增強。活性晶種特殊的表面性質(zhì)和晶種誘導(dǎo)鋁酸根離子向有利于種分的鋁酸根離子形態(tài)轉(zhuǎn)變的能力共同決定活性晶種強化鋁酸鈉溶液種分過程的活性。
關(guān)鍵字: 鋁酸鈉溶液；晶種分解；表面性質(zhì)；機理
（School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:Seeded precipitation of sodium aluminate solution can be intensified by adding active seed and the precipitation rate can be increased remarkably. The properties of the active seed prepared by reaction of sodium bicarbonate and sodium aluminate solution were characterized and the influences of the properties on seeded precipitation process were investigated. The results show that the active seed is composed of bayerite with fine particle size, large specific surface area, high surface energy and stronger solvent effect. The precipitation of sodium aluminate solution can be enhanced considerably by adding active seed, and the seeded precipitation rate can reach 65% with only 1g/L of the active seed. Besides the larger surface area, the stronger solvent effect and more positive Zeta potential of the active seed are attributed to promoting the seeded precipitation. The active seed has a higher capability to induce the aluminate ion in sodium aluminate solution converting into at the initial period of seeded precipitation, and the capability increases with the seed surface area and solvent effect. The special surface properties and the high capability of inducing aluminate ion conversion may be the cause of the high activity of the active seed on promoting the seeded precipitation of sodium aluminate solution.
Key words: sodium aluminate solution; seeded precipitation; surface property; mechanism
