Classification of flints for drill wear potential

The assessment of abrasiveness and hardness of rocks have been extensively covered by previous researchers, with little attention to flints, which were only described as highly abrasive. However, analysis of flints has shown that abrasivity of flints varies. These parameters are important inputs for the prediction of drill bit wear rate and design of various parts of drilling/tunneling/mining equipment. In this paper, a classification of flints (sampled from the English, French and Danish Chalk) which correlates with the abrasivity and hardness of flints is proposed. The results showed lighter/grey flints (with more calcite) have lower potential to cause drill bit wear as indicated by hardness and geotechnical wear indices than dark flints. This tends to suggest that even small variations in the carbonate content results in significant variation in abrasivity and that colour can be used as an indication of the potential of flints to cause tool wear.