A contractor in the north central United States is successfully using the Surestrike model 4000 hammer to break granite from a dimensional stone quarry.
This is waste rock that was either off color, wrong size, bad grain structure, etc. and is unusable for dimensional cut stone purposes (I.e. Countertops, monument stones, etc.). It had been stockpiled for many years because there had been no cost effective or efficient method to break it until the Surestrike hammer came along.
The rock has a high compressive strength (I.e. 50,000 PSI) so it is very tough to break. The size, hardness and homogenous nature of the rock add to the difficulty. Because it is a cut rock rather than a shot rock also compounded the problems and ineffectiveness of previous breaking methods. The average size pieces are about 4′ x 6′ x 10′ with many of the pieces being 6′ x 8′ x 10′ with some even larger. Prior to using the Surestrike model 4000 hammer, drop balls and hydraulic hammers were used. Most hydraulic hammers would not even break the rock. If one was found that would break the rock either the production was too low or maintenance costs were too high. Drop balls were slow and subsequently production was too low to be profitable.
The Surestrike model 4000 breaks the oversize into 24″ – 30″ minus crusher run at a rate of approximately 100 TPH which allows for a profit and for the customer to clean up the quarry.