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研究了高硫铝土矿中硫对拜耳法NaAl(OH)4种分母液蒸发排盐的影响.结果表明,NaAl(OH)4溶液深度蒸发排盐渣中主要存在Na2CO3·H2O和NaAlO2·1.25H2O,苛碱浓度300~310 g/L时能有效析出Na2CO3且不导致NaAlO2析出过高.硫对NaAl(OH)4溶液中Na2CO3、硫盐和NaAlO2析出影响很大,析出率均随硫含量增加而增加,且排盐率均在60%以上.Na2SO4对析出率影响最大,硫浓度6 g/L时排盐率可达91.33%;Na2SO3的影响稍低;Na2S对析出率影响较小,硫浓度6 g/L时排盐率仅为68.49%.将硫浓度为4.5 g/L的NaAl(OH)4溶液蒸发至苛碱浓度为310 g/L时排盐渣中存在Na2CO·3H2O,NaAlO21.25·H2O,Na2CO32Na2SO4和其他形式复盐.蒸发过程中有部分低价硫被氧化,约有7%和4%的S2氧化为S2+和S4+,7%~11%S4+氧化为S6+.Na2CO3和各价态硫化合物交互作用,影响蒸发排盐效果.
The effects of sulfur on the ebullition and desalting of NaAl (OH) 4 kinds of mother liquor in high-sulfur bauxite were studied.The results showed that there are mainly Na2CO3 · H2O and NaAlO2 · 1.25 in the deep-evaporating salt residue of NaAl (OH) 4 solution H2O and caustic soda at 300-310 g / L can effectively precipitate Na2CO3 without causing excess precipitation of NaAlO2.Sulfur has a great influence on the precipitation of Na2CO3, sulfur salts and NaAlO2 in NaAl (OH) 4 solution, , And the salt rejection rates are all above 60% .Na2SO4 has the strongest influence on the rate of precipitation, and the salt rejection rate reaches 91.33% when the sulfur concentration is 6 g / L; the effect of Na2SO3 is slightly lower; When the concentration of sulfur is 6 g / L, the salt rejection rate is only 68.49%. When NaAl (OH) 4 solution with sulfur concentration of 4.5 g / L is evaporated to Na2CO3 · 3H2O in the salt scum with the concentration of 310 g / L, NaAlO21.25 · H2O, Na2CO32Na2SO4 and other forms of double salts. Some of the low-sulfur sulfur is oxidized during the evaporation process, with about 7% and 4% of S2 being oxidized to S2 + and S4 + and 7% to 11% of S4 + to S6 + Interaction with the valence sulfur compounds affect the evaporation of salt discharge effect.