Paul Wurth SA (Luxembourg, Luxembourg):

Kappes H., Dr. Eng., Head of BA Energy and By-Products
Michels D., Mag. Sc., Process Engineer, BA Energy and By-Products, daniel.michels@paulwurth.com

Paul Wurth has approached the topic of dry slag granulation with a simple but effective method in which steel spheres and liquid slag are mixed to achieve fast cooling of the blast furnace slag while creating a product with highest possible energy content. Following different test series, where the slag quality and suitability for cement production was proven, Paul Wurth built a full scale dry slag granulation pilot plant at Rogesa’s blast furnace No 4. The first phase of this pilot plant was successfully put into operation end of 2013 and is able to process up to 8 t/min of liquid blast furnace slag. The mixing method as process for dry slag granulation with energy recovery produces cement quality vitrified slag. It is not affected by varying slag flows, varying temperatures and varying chemistries of the slag. It provides steady energy output from the heat recovery due to a buffer, which is compensating the cyclic BF production by storing the hot but solid mixture of slag and steel spheres. The process has been successfully tested for BF slag, BOF slag, EAF slag and FeNi slag. The mixing method is the most robust process in the market.