A waterless caster for mattelslag granulation

With the increasing trend to continuous smelting and converting, granulation of copper matte is gaining prominence as a means of decoupling the smelting and converting operations. Moreover, granulation is also being seen as a possible avenue to using higher grade oxygen in converters. By feeding cold-solid matte, the oxygen concentration can be increased to compensate for the lower enthalpy feed. This leads to a higher grade of SO2 in the off gas and a lower total flow rate. Current granulation technology relies on the cooling of a falling matte film by water jets; this technology, while effective, has several drawbacks including those related to safety. Noranda and McGill University have developed a new process (patent pending) for solving copper matte (or slag). It overcomes many of the negatives of current technology. The system is based on an air-cooled twin-roll caster. This new system uses no water and instead incorporates heat pipe technology to transfer the heat from the solid matte to the cooling air to produce a thin strip of 1 to 2 mm in thickness. Testing of a prototype unit demonstrated its viability. This paper describes this newly developed twin-roll casting system that is completely waterless. The advantages of this process as well as the findings from several tests are also detailed.