Valorization of Finnish mining tailings for the use of ceramic industry

The Academy of Finland funded CeraTail project aims to find low energy methods and their combinations to produce porous ceramics from mining tailings for the use of ceramics technologies. The ceramic producing methods used are... [ view full abstract ]

The Academy of Finland funded CeraTail project aims to find low energy methods and their combinations to produce porous ceramics from mining tailings for the use of ceramics technologies. The ceramic producing methods used are alkali activation, phosphate bonding and reaction sintering. Investigation of mine tailings utilization as a secondary raw material contributes a zero waste concept implementation.

In order to valorize mining wastes for ceramics production, six Finnish mine tailings were selected, investigated and classified on the basis of their chemical and mineralogical contents. The tailings were divided in three groups: SiO₂ rich felsic mining tailings (FMT), tailings rich in Mg-Fe bearing minerals (MgFeMT) and tailings rich of carbonate minerals (CMT).

Experimental work demonstrated that MgFeMT materials with an added Al source are viable for geopolymerization. Based on a literature review, FMT materials can be potential source materials for the production of geopolymers, but a high initial Si:Al ratio (in quartz-rich FMT) may lead to partial geopolymerization. Reaction sintering experiments showed their viability for mullite-type ceramics. Experiments with CMT materials yielded promising results in terms of phosphate reactivity, but none of the tailings of the present study were usable for phosphate bonding at the macroscopic level, i.e. for producing bulk ceramic pieces.