1989 Volume 75 Issue 6 Pages 902-909
Direct determination of Si in molten pig iron without sampling has been developed with ultrafine particles (UFP) generation/inductively coupled plasma (ICP) emission spectrometry. At first, analytical conditions for UFP generation with spark discharge method, transportation of UFP and determination of Si in UFP were investigated with block steel samples. Si could be determined as good as those of the conventional spark emission spectrometry.
On the next stage, the UFP/ICP system was installed at a production site for the direct analysis of molten pig iron. It was found to be very difficult to apply spark discharge as UFP generation source, because graphite carbon which was spitting from molten iron surface interrupted to make normal spark discharge. Ar gas bubbling method was applied as UFP generation source instead of spark discharge method. The iron UFP could be generated by means of injecting Ar gas into molten iron, and they were transported in an Ar gas stream through 40 m of tube to an ICP torch. The analytical results of 0.2 to 1.0% of Si in molten iron agreed with those obtained by the conventional method after sampling. The time required for analysis of one cycle is approximately 80 s. The present method is more suitable for direct analysis of Si in molten iron.