DASARI SURESH ASST. MANAGER (MINING)

 What is fragmentation ?  Fragmentation is the process of breaking the solid in-situ rock mass into several smaller pieces.  Breakage of rock mass is assisted by conventional drilling and blasting operations.

 Optimum rock Fragmentation : -  The rock fragmentation is said to be optimum when it contains maximum percentage of fragments in the desired range of size.  The desired range usually means fragment size demanded and can be effectively utilized by customers for further processing.

 Signification of optimum rock fragmentation : -  To fulfill the varying demands of different consumers.  To reduce the Shovel digging time, loading time and cycle time.  To reduce or to over come Secondary blasting through reduction of oversize generations (boulders) in primary blasting.

 To reduce the cost of Crushing and grinding and uphold the economics of mining.  The rock must be fragmented in such a way that further processing (simply called Milling) is not required. The cost of Milling should be minimized when it should be optimum fragmentation in Primary blasting.

 Achieving Optimum rock fragmentation : -  To achieve an optimum rock fragmentation a blast with optimized controllable parameters should be designed so that the effects of the uncontrollable parameters could be minimized.  By conducting trails blasts the controllable parameters can be fixed for a better fragmentations.

Controllable parameters Bench Height Hole dia and depth Sub grade drilling Hole inclination Charge column height Stemming height Stemming material Pattern Burden to Spacing ratio Blasting direction Initiating system Initiating sequence No. of free faces Explosive type Explosive energy Loading method Water

Un-Controllable parameters Geology Material strengths and properties Structural discontinuities Weather conditions

 Advanced Blast Monitoring  Main Objectives : - To achieve desired fragmentation in primary blasting Minimum unwanted effects such as ground vibrations, air blast noise, fly rock, generation of oversize boulders, toe formation and back break..etc.

 Phases of Blast Monitoring :- Pre – Blast monitoring In – Blast monitoring Post – Blast monitoring

 Pre – Blast Monitoring : - Surveying the blast site Site characterization Explosive characterization Monitoring the blast parameters Drilling patterns

 In – Blast Monitoring :- Charging methods Photography methods Monitoring the Ground vibrations and air-blast noise

 Post – Blast Monitoring Fragment size analysis Monitoring performance of productivity of loading machines Monitoring the Crusher performance Boulder (or) Over size count

 Fragmentation size analysis Sieving or Screening Shovel loading rate, cycle time Photographic methods Crusher output and delays at Crusher

 Sieving and Screening

Wipfrag image analysis KUZ-RAM fragmentation analysis  Photographic Methods