新提取混合溶剂氯化铵-乙二醇-乙醇用于钢渣中游离氧化镁含量的测定

Use of a New Mixed Extractant of NH_4Cl,Glycol and Ethanol in the Determination of Free Magnesium Oxide in Steel Slags

通过正交设计对用新混合溶剂提取钢渣中游离氧化镁时试样量、溶剂用量、氯化铵用量以及加热时间等因素进行了优化。确定了最佳条件:1取样量:0.3~0.5g;2乙二醇-乙醇(6+1)混合溶剂加入量:30mL;3氯化铵加入量:达到nNH4Cl/nCa+Mg≈18~25.8之间;4样品中f-MgO提取条件:加热至微沸并回流20min。提取反应混合液,经冷却和离心分离,取上清液,用盐酸(1+1)溶液酸化并定容至100mL。分取部分溶液,用EDTA滴定法测定其钙、镁合量和钙含量,从而计算f-MgO的含量。试验结果表明:在所选定条件下,f-MgO的回收率均大于97%。应用此方法分析了4种来自不同钢厂的钢渣样品,所得f-MgO测定值的相对标准偏差(n=5)在0.79%~2.2%之间。

Optimum conditions for extraction of free magnesium oxide(f-MgO)from samples of steel slags using the new mixed-extractant of NH4 Cl,glycol and ethanol were studied by orthogonal designing,and the following results were obtained:1amount of sample taken:0.3-0.5g;2amount of the mixed solvent of glycol and ethanol(6+1)required:30mL;3 amount of NH4 Cl required:keeping the ratio of nNH4 Clto nCa+Mgin the range of 18 to 25.8;and4treating the sample with the mixed extractant by heating to gentle boiling and refluxing for 20 min.The reaction mixture was cooled and centrifuged,the supernatant was taken,acidified with HCl(1+1),and made up to 100 mL.Aliquots of which was used for determination of(a)sum of Ca and Mg;(b)Ca only.by EDTA titration.Content of f-MgO was calculated from the difference of(a)and(b).It was shown that under the prescribed conditions,the values of recovery of f-MgO found were all greater than 97%.Four slag samples obtained from different steel plants were analyzed by the proposed method,values of RSD′s(n=5)calculated from the results of f-MgO contents were in the range of 0.79%to 2.2%.