Several processes were tested at the laboratory in order to purify coarse grain European andalusite. Both of them give very good technical results.
One purification process (Roasting + HGMS) was tested in a pilot plant. The results were as good as those achieved at the laboratory, dealing with iron content and yield.
Several hundred tons of new coarse grain andalusite were produced at the pilot plant. Four European refractorists have produced several hundred tons of new low iron andalusite refractories (bricks and castables).
All the new andalusite refractories produced, give good technical results at the laboratory. Then several hundred tons of new andalusite castables and bricks were tested in industrial conditions of an European steel plant.
Technical and economical results do not seem interesting for steel ladles (when CaO is high in the slag) and torpedo cars. But lining the bottom of some tundishes with low iron andalusite castable could present interest.
The new low iron andalusite refractory presents a very good resistance to CO attack. This could be interesting for special parts of blast furnace.
Other refractory users (ceramic industry, glass industry, ...) could be interested by these new low iron andalusite refractories.
Andalusite has been introduced in the industry as a refractory material in the seventies. The production inside the EC represents only 35% of the needs, and the european andalusite is more in competition with low cost south-african andalusite, chinese bauxite and synthetised mullite. The restriction of development of european andalusite related to the high iron content (1% Fe2 O3),particularity in coarse grains. This iron produces dark spots in the white bricks and decreases thermomecanical data. DAMREC, producer of andalusite,Catholic University of Louvain and the refractory laboratory of HOESCH STAHL AG,user of refractories, want to undertake the iron purification study of andalusite in relation to the improvement of the refractory properties as follows:
- To decrease iron content until 0,6% Fe2 O3 using original processes:
oxidizing acid leaching, roasting followed by High Gradient Magnetic Separation, Heavy Medium Separation, of iron bearing minerals.
- To study refractory properties up to 1700 C of the purified andalusite produced,alone or mixed with added corundum,in competition with usual andalusite,spinel refractories and bauxite materials.
Both purification and refractory studies include laboratory testwork,pilot or plant trials testing,technical and economical evaluation. In case of success,this project will end to new refractory materials(>60% Al2 O3,< 0.6% Fe2 O3) in the range 0-2mm capable to replace competitive materials.
Funding SchemeCSC - Cost-sharing contracts