This correlation is a first attempt, and, as such, is admittedly an approximation. That such a correlation should be possible is indicated:
By the fact that drilling data obtained from Kirkland Lake mines have been satisfactorily related to the work indices, as well as the drilling data obtained by Professor Salman of Mc-Gill University.
By the fact that the work indices have also been satisfactorily related to blasting data from the mines.
The work index of drilling and blasting has been shown to be an important parameter for evaluating and controlling drilling and blasting operations in mines.
The idea of this paper was suggested by the distinguished alumnus of the Colorado School of Mines, Fred C. Bond, who has devoted a lifetime to the basic study of comminution and who gave us "The Third Theory of Comminution" (1952).
The appearance of this theory created an impetus in research on fundamentals of comminution which has become international in scope. The literature on this research is assuming the nature of an avalanche and recently it resulted in a Bibliography volume on Crushing and Grinding (Department of Scientific and Industrial R esearch,1958). This is a monumental volume containing lists of all the published articles on comminution together with pertinent abstracts treating each phase of comminution separately. It is interesting to note that there are 30 abstracts from Mr. Bond's published works, probably the largest number of abstracts given to any author in this volume.
One of the authors of the present paper, after reading and recognizing the importance of "The Third Theory of Comminution," prepared a review of the work of recent investigators on grinding fundamentals and published it as grinding criteria (Djingheuzian, 1952).
In a discussion of this paper at the Annual Western Meeting of the Canadian Institute of Mining and Metallurgy in Winnipeg, October, 1952, Van H. Smith, well known mineral dressing engineers, aid:
"I suggest that a study be made of drillability of known and unknown ores, using same diameter drill bit, same strokes per minute and same air pressure, and that from the results of such a study an attempt be made to tie down whether grindability in a ball mill can be roughly measured by the drilling characteristics obtained under such similar test conditions."
The first step in Canada towards accomplishing this was made by the Canadian Ingersoll-Rand Company when in 1954 it engaged the services of Professor T. Salman of McGill University to conduct investigations on physical properties and relative drillability of mine rocks. This work was carried on for three consecutive summers. The Canadian Ingersoll-Rand Company has made this information available to the authors, and it is part of this paper. The accuracy and detailed care taken in the research work have proved most valuable.
Canadian Industries Limited, a supplier of explosives to Canadian mines, has been most helpful in supplying information.
Questionnaires were sent to Canadian mines the grinding work indices of whose ores were known to the authors.
