I don't know what LD slag is, but I presume that it has a liming value and the reason it is applied. In that caes assume that all the heavy metals are available and apply the material on that basis considering local regulations
LD Slag is Steel factory byproduct and it contains heavy metal like Chromium, lead, nickel, cadmium and arsenic. So, What should be the limiting value of heavy metal in the slag?
Actually the heavy metals found in LD slag is all toxic in nature,many r found to be carcinogenic also , More than 0.01ppm is not permissble in any edible items
Metal concentrations in slag could be compared with naturally occurring background levels of metals in soils, see the paper attached (D.M. Proctor et al,, "Physical and Chemical Characteristics of Blast Furnace, Basic Oxygen Furnace, and Electric Arc Furnace Steel Industry Slags", 2000).