What is Blast Hole Drilling?
Blast hole Drilling is a technique used in mining whereby a hole is drilled into the surface of the rock, packed with explosive material, and detonated. The aim of this technique is to induce cracks in the inner geology of the surrounding rock, in order to facilitate further drilling and associated mining activity.
The initial hole into which the explosives are packed is known as the “blast hole”. Blast hole drilling is one of the primary surface drilling techniques employed in mining operations today.
Where is Blast Hole Drilling Used?
Blast hole drilling is traditionally used wherever the mining company wants to explore the mineral composition or potential mineral yield of the area demarcated for their mining interests.
Blast holes are thus a fundamental step in the exploratory mining process, and can be employed in both surface mining operations and underground mining operations to varying degrees with varying effects or results.
Blast hole drilling can also be employed in quarrying endeavors.
Why is Blast Hole Drilling Used?
Blasthole drilling is essentially carried out in order to break up rock and hard minerals in order to make it easier for the mining crew to get to the resources being mined.
Basic Blast hole Drilling Process:
Step 1 – Surveying the location
Before the blast hole drilling can begin, the proposed site needs to be inspected, and certain decisions need to be made with regards to the hole size/diameter, the type of drill or drills that will be required, etc.
These decisions will be based on the findings of the initial site survey.
The site survey will analyse the nature of the proposed mining operation, the nature of the rock, soil, ground, and/or mineral in question, and will impact the road going forward with regard to the blast hole drilling processes.
Step 2 – Researching the rock types and formations
Once the surveying processes have provided the surveyors with the raw data, they will turn this data over to researchers, who will then do the necessary research in order to plan effective and safe drilling patterns.
Step 3 – Plan drilling patterns
Once the researchers have determined the most effective, efficient, and safest way to proceed, the project manager will take over and draw up the necessary drilling plans.
Step 4 – Drilling the blast holes
This is where the actual blast hole drilling starts.
So by now all the machinery will have been procured (hired, acquired, what have you) and will be on-site, and ready to begin drilling the blast holes! The researchers’ data will reveal how deep and how wide the diameter of the blast holes should be, as this will depend on the results of the survey.
In other words, on the nature of the mineral being mined, the nature of the surrounding rock/ground/soil etc.
Step 5 – Breaking up the rock
Once the blast holes have been drilled they will be packed with explosives. What kind, and the amount of explosives used will have been determined based on the research conducted; just like the size and depth of the blast hole was determined based on the research.
The explosives will then be remote-detonated in order to break up the rock.
Step 6 – Clean up process
Just like at a party, once the exciting part is over, somebody has to stay behind and clean up the mess! In underground mining, the tunnel will be cleared of debris, and the tunnel will be suitably reinforced.
Otherwise, as in open mine blasting, the rock will be excavated and hauled.