Utilization of granulated lead slag as a structural material in roads constructions

Pyrometallurgical processing of lead ores generates large amounts of slag which is stockpiled as chunk or granules. Romanian dump heaps of such slag produced in the period 1972-1998, occupy an area of 4522 m(2) and a volume of 6616 m(3). To assess the possibility of using this material in road construction, a complex characterisation of this waste has been carried out. X-ray diffraction, microcompositional and microstructural analysis revealed the presence of Fe, Zn, Pb, Cu sulfides, Fe, Ca, Si oxides and complex Mg, Al silicates etc. Following investigations were drawn several conclusions. According to the analysis of leachate specific indicators for the three types of slags analyzed (cooled slowly lead slag; granulated lead slag; deposited lead slag), granulated lead slag has the lowest lead content; value that exceeds the maximum allowed (current legislation). Analysis of acid drainage revealed that cooled slowly lead slag is not acid generating, granulated lead slag is uncertain and deposited lead slag is acid-generating. To determine the physico-mechanical and geotechnical properties Proctor compaction test, Californian index CBR test, permeability test and direct shear test were performed. Results from these investigations show an approximation of the values of granulated slag and sand .