Fata Aluminum experience on thermal regeneration of waste foundry sand started in 1982, both for sand bonded with organic resins and for green sand bonded with bentonite.
At that time Fata Aluminum developed its own first thermal sand regeneration fluid bed furnace, and since then, Fata supplied more than 60 plants for organic resins and 10 plants for green sand process, with capacities from 1 to 25 t/h, to customers all over the world.
All Fata Aluminum furnaces are based on the fluid bed technology, as well as the mechanical sand surface attrition machine, developed especially for the green sand regeneration, to eliminate bentonite.
lnorganic sand regeneration: a necessity for the "Foundry of the Future"
Due to ever increasing attention to environmental problems related to the solvents emissions given by traditional foundry activities, the potential for inorganic resins was very promising thanks to the zero emissions of this process. Therefore, in 2014 Fata launched his R&D project and the first key step was to invest in a new pilot plant [Fig.1], composed by:
- One crusher
- One mechanical attrition machine (M), single cell, complete with its own de-dusting unit
- One thermal treatment unit, Easy Rec type (T)
- An enhanced laboratory to test AFS, LOI, ADV, clay and core strength
Fig. 1.Fata Aluminum sand regeneration pilot plant
The system is designed to treat organic and inorganic sands combining mechanical attrition (M) and thermal treatment (T), so as to regenerate sand with M, T, M+T, T+M, M+T+M processes.
This pilot plant is currently used for activities tied to:
- Internal R&D tests
- Customer sand tests
- Process qualification
- Inorganic sand regeneration tests
Since in 2014 the existing literature on this subject was not convincing, we decided to run our plant with all the possible treatment sequences, using both the furnace and the mechanical attrition machine. The first results told us the following:
- Thermal treatment itself doesn't regenerate the sand
- Thermal + Mechanical treatment doesn't regenerate sand
- Mechanical + Thermal treatment regenerates the sand
Treatment yield of the M+T treatment was satisfying (close to 85-90%), so we focused in the optimization of the M+T process, regenerating sand at different temperatures and different mechanical treatment settings, finding out that:
- Sticking problems during fluidization increase with the increasing of the treatment temperature
- Mechanical treatment has to be set to find the best compromise between sand yield and sand quality
- Core strength increases with the increasing of the thermal sand regeneration temperature
Based on the test results, we decided to develop a new concept of furnace to regenerate the sand at the highest possible temperature, keeping in mind the sticking problems. This new patented product, called lno Rec [Fig.2], has a capacity of 1 to 10 t/h and is based on the fluid bed technology.
In parallel we kept on running tests with our pilot plant, regenerating inorganic sand for more than 10 cycles, so as to verify the core strength values after a certain number of recycles.
Fig. 2.Ino Rec 1.5 tlh sand regeneration plant
The results confirmed that:
- The cores produced with the regenerated sand have strength characteristics higher than the ones manufactured with new sand
- The process yield is close to 90%
- The new sand addition is very limited
The first industrial lno Rec furnace, having a capacity of 1,5 t/h, has been installed in an Italian foundry at the beginning of 2017 and it is currently supplying the core shop for the manufacture of automotive products.
The customer laboratory tests confirmed that the regenerated sand quality is optimal, even after several re-cycles.
Fig. 3.Ino Rec 5 tlh sand regeneration plant
A second lno Rec furnace with a capacity of 5 t/h [Fig.3] has been installed in 2018 and a third 5 t/h lno Rec is currently under manufacture, allowing the customer to double its sand regeneration capacity needs by the end of year 2019.
MEET US AT GIFA HALL 17 BOOTH 17D61