Properties of fired dolomite refractories with tar bond

Conclusions The laboratory specimens made of tar-bonded fired dolomite showed an apparent porosity of 8 to 18%; slightly better porosity was shown by specimens made with more fully sintered dolomite.The tar barely permeates the dolomite grains.When they are stored, the porosity is increased and the bulk density and strength of the specimens are reduced. This is less obvious after coke firing.Bricks made of all the tested dolomites with the addition of 8 and 6% tar at a pressure of 500 kg/cm² showed a bulk density of 2.6 g/cm² or more. Similar results are obtained when making the bricks by pneumatic tamping.For tests in the lining of converters we recommend blocks made of freshly fired dolomite with an apparent porosity of 5–10 and 15–20 and a grain composition lower than 15–10 mm. As a bond, 6 to 8% tar containing 65–70% medium coaltar pitch and 35–30% anthracite oil should be added. The blocks have to be pressed at at least 500 kg/cm².