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富锰渣中含锰和铁较高,以EDTA络合滴定钙、镁时必须将它们除去,以往用氯酸钾除锰,氨水沉淀铁、铝等干扰离子,或用氨水-过硫酸铵法,六次甲基四胺—铜试剂法进行沉淀分离,以氰化物等试剂来掩蔽,操作手续较为繁琐,而且污染了环境又得不到理想的结果。 本文首先推荐在pH为12时,以三乙醇胺(TEA)和通入空气使Mn(Ⅱ)氧化为Mn(Ⅲ)—TEA络合物同时亦能将铁掩蔽,从而消除了锰和铁的干扰,便可单独以EDTA测定氧化钙;其次介绍在酸度为1～2.5N下,于30℃左右时,用亚铁氰化钾(Ⅱ)作为无毒多金属沉淀剂和掩蔽剂使锰和铁沉淀为白色粒状的Mn_2[Fe(CN)_6]和Fe_2[Fe(CN)_6],而钙、镁的亚铁氰
Rich in manganese-rich slag containing manganese and iron, EDTA complex titration of calcium and magnesium must be removed, in the past with potassium chlorate manganese, ammonia precipitation of iron, aluminum and other interfering ions, or ammonia - ammonium persulfate, six Methylenetetramine - copper reagent precipitation separation, to cyanide and other reagents to cover, the operating procedures are more complicated, but polluting the environment and not the desired results. In this paper, we first recommend that the oxidation of Mn (II) to Mn (III) -TEA complex with triethanolamine (TEA) and air at the pH of 12 at the same time can also mask the iron and thus eliminate the interference of manganese and iron , Can be measured by EDTA alone calcium oxide; followed by the introduction of acidity of 1 ~ 2.5N at about 30 ℃, the use of potassium ferrocyanide (Ⅱ) as a non-toxic multi-metal precipitating agent and masking agent of manganese and iron Precipitation of white granular Mn_2 [Fe (CN) _6] and Fe_2 [Fe (CN) _6], and calcium, magnesium ferrocyanide