Abstract: A series of preferably superimposed low inclination troughs containing serial inclined blade rotating mixers and transporters is provided to react dry materials and liquids, and in particular borax with water and acid, in a manner which avoids the formation of refractory lumps and the like. Those are at least two series of rotating blades to both mix and lift the materials into a gas drying stream passing along the troughs. A shearing type grinder or hammer mill is positioned intermediate of the troughs to grind or break up the material part way through the apparatus. Material is discharged from the apparatus in a dry finely comminuted form which does not form lumps upon standing.