Abstract: In order to improve the resource utilization of slag powder， reduce the environment pollution of surface deposit and efficiently recycle the solid waste， the mechano-chemistry effect of low activity acid slag powder has been studied by means of microanalysis and strength test. The results show that the characteristic particle size of slag powder particle size after 30 min， 60 min and 90 min mechanical grinding decreased from 22.49 μm to 18.55 μm， 13.80 μm and 10.61 μm. The phase of slag powder does not change by mechanical grinding， but the surface morphology changes from massive particles with irregular polygons into small particles with pebbles and smooth surface. The compressive strength of filling body is increased with grinding time extension under the same conditions. After 60 min mechanical grinding， the compressive strength of test block meets filling requirements of the mine， so the potential activity of slag powder can be significantly improved by mechanical grinding， in turn the comprehensive strength of filling sample is increased.

Key words: Low activity acid slag powder, Mechano-chemistry effect, Grain composition, Cementitious materials, Compressive strength