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:0.3~0.5 g;② 乙二醇-乙醇(6+1)混合溶剂加入量:30 mL;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20 min。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100 mL。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 NH4Cl, glycol and ethanol were studied by orthogonal designing, and the following results were obtained: ① amount of sample taken: 0.3-0.5 g; ② amount of the mixed solvent of glycol and ethanol (6+1) required: 30 mL; ③ amount of NH4Cl required: keeping the ratio of nNH4Cl to nCa+Mg in the range of 18 to 25.8; and ④ treating 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%.