Energy and cost effective casting of ferroalloys

The large potential for reducing specific energy consumption by reducing the amount of alloy lost as metal fines during casting and crushing of ferroalloys, was the underlying idea that provided the motivation for the eCAST project. The project was focused on understanding the governing mechanisms for generation of fines during casting and crushing, and how to reduce this phenomenon through modification of the applied casting and crushing technology and procedures. A 99,5 % silicon alloy and a SiMn alloy were selected as case-alloys for the eCAST project. A large task was started up to thoroughly document todays casting and crushing practice of the alloys, and its consequences for energy consumption and production yield. A large-scale instrumented industrial casting experiment was performed with the selected silicon rich alloy. Laboratory casting experiments utilizing very slow cooling rates and experiments with rapid cooling rate were also carried out for this alloy. The characterization work for the material from all three solidification conditions are reported in the Thesis - Solidification of Silicon - Macro and Microstructure as Functions of Thermal History and Composition of Ph.D. Maria Førde Møll. At Glencore Manganese Norway AS three large-scale experiments on casting of silicomanganese with different cooling and solidification conditions were carried out in March 2013. Due to problems with some thermocouples, two of these experiments were successfully repeated in February 2014. At Eramet Norway Kvinesdal AS one large-scale experiment with casting of silicomanganese was carried out in March 2013. Casting materials from all these experiments were submitted to metallographic investigations and to crushing and sieving experiments, knowing their solidification and cooling history. The eCAST project and example results were presented at the FFF-seminar "Energidagen" in Trondheim in September 2012. One publication describing and discussing the results from the work on casting of silicon alloys within the eCAST project was presented at the INFACON XIII conference in Almaty in Kazakhstan in June 2013. Results from the project were presented at the FFF Work-Shop; Production of manganese ferroalloys - A meeting between research and industry in Trondheim, 4th of December 2013. A result from the project was presented at the conference Silicon for the Chemical and Solar Industry XII in Trondheim, 2014-06-23 - 2014-06-26.

In ferroalloy production metal fines are the undesired fraction of the produced alloy having a size below the minimum size limit after sieving. Fines are normally collected and recycled into own production line, or sold as a low priced inferior product. T he amount of fines generation depend on properties of the individual phases present in the alloy, and how these phases respond to the applied crushing technology. The amount of the different phases depends on chemical composition, and on applied casting c onditions. Thus, the applied technology and procedures for casting and crushing play important roles in determining energy yield and production efficiency of ferroalloys through the significant influence on fines generation. The large potential for redu cing the specific energy consumption by reducing the amount of alloy lost as metal fines during casting and crushing is the underlying idea that provides the motivation for the eCAST project. This project will focus on understanding the governing mechanis ms for generation of fines during casting and crushing, and how to reduce this phenomenon through modification of the applied casting and crushing technology and procedures.