Former Sakab, now Ekokem, sought development funds from the EU financial instrument LIFE, for developing a method for the stainless steel industry, which converts waste product filter cakes (Hydrofluss) to raw material for use in the melting process.
The project, Life10 ENV/SE/042 Hydrofluss, was chosen for funding and Sakab received financial contribution to accomplish the project.
Project time schedule
The project started in September 2011 and was finished October 1 2013. In the final report is decribed
The project was divided into 10 different activities (actions). Action 1 Project Management, Action 2 Monitoring, Action 3 Evaluation, Action 4 Technical preparation and test, Action 5 Preparation for demonstrations, Action 6 Small scale demonstration, Action 7 Construction , Action 8 Pilot scale demonstration, Action 9 Dissemination, Action 10 Networking, Action 11 After-Life communication plan.
Part of the steel industry uses a mineral of calcium fluoride (fluorspar) during the refining of the steel melt. Fluorspar is today mined in a few places in Asia and Central America. The limited assets of the mineral lead to high commodity prices and long-range transports.
When steel products are pickled, large amounts of filter cakes are formed as waste. These filter cakes contain a lot of calcium fluoride, but also a lot of water which is strong bonded to the material. A process that could remove all the water, would make it possible to use the dried filter cakes as a replacement for the mineral fluorspar, and in that way reduce the need of new calcium fluoride in the slag processes. Outokumpu name these dried filter cakes for non-toxic recycling Hydrofluss®.
Vacuum extraction was used
Earlier tests (i. a. at Sakab) show that it is possible to dry these filter cakes at high temperature, but it is costly, and cause a great challenge to clean the flue gases. This development project will use vacuum extraction. In that way the filter cakes are dried at a much lower temperature and with reduced flue gas flow. Since vacuum extraction has not been used in this way before, there is a need for a set of different tests, starting in small scale.
The project will give cost reductions and environmental benefits
In the manufacturing of stainless steel, calcium fluoride mineral is used as fluxing agent for the slag during the conditioning of the steel melt. When the steel is pickled, large amount of filter cakes are produced as waste. These filter cakes contain a lot of calcium fluoride, but also a lot of water, which is strong bounded to the material.
A process that can remove all the water, will make it possible to use the dried filter cakes as a replacement for virgin fluorspar in the slag processes as a closed loop non-toxic recycling process.