In this paper we give an overview of the results for structure and properties of iron-based melts obtained during the past decades. The main attention is paid, firstly, to impurity effects, which are still poorly understood. Secondly, the competition between BCC-and FCC-like local ordering in the melt is discussed in detail. The article provides an overview of the relevant experimental data and their theoretical description. From methodological point of view, along with a direct diffraction study of the structure, a large amount of information is provided by measurements of such physical properties as magnetic susceptibility, electrical resistivity, viscosity, density. For example, magnetic susceptibility, together with electrical resistivity, makes up a pair of electron-sensitive properties that allow one to judge the nature of short-range order in the system, distribution of impurities, and doping effects. In particular, it becomes possible to determine in dynamic mode which phase appears first during crystallization; it is found that in some cases this is a metastable delta phase. The study of the entire complex of properties allows one to influence the melt structure and properties by using small additions. The oscillating nature of their influence makes it possible to achieve significant effects by small changes in concentration. More over, it becomes possible to control the melt structure and the process of primary crystallization. The results discussed in the article give an example of cooperation between scientific laboratories and metallurgical enterprises. In recent years, there has been a favorable situation for its large-scale resumption. The purpose of the work is to show the possibilities of such cooperation on this retrospective example.