Blast fragmentation directly affects crusher performance, SAG mill throughput, and overall mine productivity. In this video, we explain the mine-to-mill approach, discuss fragmentation targets, geological domains, powder factor optimization, and review a real-world case study demonstrating how better blast design can improve throughput without additional capital investment.
Video transcription
Introduction
What does a processing plant actually need from blasting operations?
For primary crushing, P80 typically ranges between 200 and 600 mm depending on the crusher type. By the time the material reaches the SAG mill, the target size is usually between 150 and 250 mm.
The Importance of Fragmentation
The amount of fine material below 25 mm is also important. The key is balance.
A certain amount of fines is beneficial, but excessive fines can create dust, handling issues, screening inefficiencies, and material losses. Conversely, oversized material larger than one meter often requires secondary breaking, increasing operating costs.
The Mine-to-Mill Connection
The relationship is straightforward:
- Blast design influences rock fragmentation.
- Fragmentation affects crusher performance.
- Crusher performance impacts SAG mill throughput.
Reducing P80 by just 100 mm in hard ore can increase SAG mill throughput by 5–10% while reducing specific grinding energy by 3–6%.
This is where drilling and blasting become value-generating activities rather than simply operational costs.
Common Industry Challenge
Many open pit operations still design blasts independently from processing requirements.
Drill and blast teams often focus on: - Flyrock control - Vibration limits - Safe execution
While these objectives are essential, inconsistent fragmentation creates downstream processing problems.
Variable crusher feed leads to fluctuating mill performance, even though the root cause may originate during blast design.
Integrated Mine-to-Mill Approach
Modern mining operations increasingly adopt integrated workflows.
The process begins with geological domain analysis and rock mass characterization. Methods such as RQD and rock competency assessment help identify areas requiring different blasting energy.
Operations then use fragmentation measurement systems to evaluate actual blast performance and correlate results with crusher and mill performance.
Measuring Blast Results
Common fragmentation measurement technologies include:
- WipFrag
- Split-Online
- Motion Metrics
These systems provide quantitative fragmentation data and support continuous optimization.
Aligning KPIs
Blast performance should not be evaluated solely by:
- Drilling accuracy
- Powder factor
- Vibration control
- Safety metrics
KPIs should also include plant performance indicators because the ultimate objective is stable and efficient production.
Geological Domain-Based Blast Design
Many operations now maintain multiple blast designs for different geomechanical zones instead of using a single template across the entire pit.
Blast parameters are adjusted according to actual rock mass conditions.
Case Study
An iron ore operation mining magnetite quartzite with compressive strength of approximately 180 MPa divided the deposit into geological domains.
Powder factor varied from 0.72 kg/m³ in softer rock to 0.98 kg/m³ in harder zones.
Importantly, total explosive consumption did not increase. Energy distribution simply became more accurate.
Results included:
- Oversize reduction from 5.8% to 2.1%
- Primary crusher throughput increase of 8%
- No capital expenditure required
Conclusion
Successful mine-to-mill optimization starts with understanding the rock mass and applying the right blasting energy in the right location.
Improved fragmentation creates measurable benefits throughout the mining value chain, from drilling and blasting to crushing, grinding, and plant performance.