硫酸铁铵滴定法测定赤泥中二氧化钛

Determination of titanium dioxide in red mud by ammonium ferric sulfate titrimetry

利用氢氧化钠的强碱性和消融性,将赤泥试样经氢氧化钠在马弗炉中加热熔融。熔融物先在温水中洗出,加入30mL盐酸溶解,然后加入铝片还原,采用碳酸氢钠溶液保护,最后以硫氰酸铵溶液作为指示剂,采用硫酸铁铵滴定法测定赤泥中的二氧化钛含量。研究了样品用量、粒度、氢氧化钠用量、焙烧条件、溶样条件和保护溶液对测定的影响,结果表明:最佳实验条件是氢氧化钠用量为6g、焙烧温度为650℃、焙烧时间为20min、还原剂为2.2g铝片、保护溶液为饱和碳酸氢钠溶液、滴定前放置时间不超过15min。采用实验方法对实际赤泥样品中二氧化钛进行测定,测定值与电感耦合等离子体原子发射光谱法测得结果相近,相对标准偏差(n=5)均小于0.2%。

The red mud sample was heated and fused in muffle furnace with sodium hydroxide using its strong basicity and ablation property.The fusant was firstly leached in worm water followed by dissolution with 30 mL of hydrochloric acid.Then,the aluminum sheet was added for reduction in presence of sodium bicarbonate solution for protection.Finally,the content of titanium dioxide in red mud was determined by ammonium ferric sulfate titrimetry using ammonium thiocyanate solution as indicator.The effect of sample dosage,particle size,sodium hydroxide dosage,roasting condition,sample dissolution condition and protection solution on the determination was investigated.The results showed that the optimal experimental conditions were as follows:the dosage of sodium hydroxide dosage was 6g,the roasting temperature was650 ℃,the roasting time was 20 min,the reducing agent was 2.2g of aluminum sheet,the protection solution was saturated sodium bicarbonate solution,and the placing time before titration was less than 15 min.The proposed method was applied to the determination of titanium dioxide in actual red mud sample,and the found results were consistent with those obtained by inductively coupled plasma atomic emission spectrometry.The relative standard deviation(RSD,n=5)was less than 0.2%.