CONSTITUENTS AND POROSITY OF LEAD CONCENTRATE PELLETS PRODUCED IN THE TREPCE PLANT

摘要

Both composition and porosity of pellets are the main parameters influencing the reductive melting process in water-jacket furnace during the roasting of sulfide lead concentrate. Roasting in a smelter located in Trepce is done at about 900℃, for pellets which are composed of PbS, CaCO_3, Fe_2O_3, and SiO_2. In order to faciltiate the formation of slag in the reductive melting, the pellets must have the proper content of CaO, SiO_2, and FeO, and porosity. The plant's practice indicates that pellets with porosity of 18% do not melt adequately in the water-jacket furnace. The optimum porosity, for the proper melting of pellets needs to be 32-40% and can be achieved when pellets are loaded with more than 10 wt.% CaO. Pellets with less than 10% CaO have a limited network of pores, such that reactive gases cannot reach the entire ore structure. Also, the composition of the pellets must satisfy the ratio of CaO : SiO_2 : FeO = 1 : 1.2 : 1.8 to facilitate the formation of slag in the reductive melting process.