key to Productive Mining: Blast design

Blasting and Mining cost

Blasting operation is one of the Technology use in breaking rock mass into smaller sizes. Since rock exist as an Anisotropic and heterogenous massive solid at the lithosphere it therefore requires the use of energetic Technique like blasting to generate sufficient shock wave for fracturing and gas Energy for casting down. Mining operation is known to be a capital intensive project whether small scale or large scale, likewise the place of safety is insuschangable. At this expenses, Blasting operation dictates the cost of other preceding operation and even the downstream operations. Blasting operation is a professional work that and a bit difficult to design for ordinary person since two major factors affect the output result which are the controllable factors such as burden and other hole geometry parameters and uncontrollable factors such as rock strength and other geological and geotechnical properties of rock.

Making balance between this two factors to ensure maximum energy is supply for optimum fragmentation becomes a difficult task. Failure to achieve this gives high cost Blasting, environmental challenges such as flyrock, misfire, overbreak, ground vibration among others. Minimizing this in small scale mine who make use of jack hammer and other small hole diameter drill machine becomes a problem an therefore causing diverse limitation in Nigeria mining sector and other countries.

Open pit mine design: Key to optimize productivity

Short ways reduce open pit mine operation cost:

1. Proper design: remember proper preparation prevent poor performance (5p's  key of good operation system). When it comes to open pit mining I always like to make mine plan and Design first as the key ways to optimize and garantee profitability.

See through this: The following factors are the dictator of stripping ratio (Stripping cost), Drilling and Blasting, loading and haulage operation, then processing operation.

Find the factors below and how that affects the about operation:

Factor number 1: Bench height: This is the maximum vertical extension of the mine bench also define as the vertical distance from the toe to crest of a bench. This factor determine the type of loading equipment that will be strictly permit in the mine for loading because, the loading boom of the equipment must not be longer than the bench height. Small loading equipment means low production or high cost of getting enough loading equipment that will fit for your production target as shown by your fleet design.

It also affect dilution control in the mine, heigh bench height result into large hole Drilling, and large powder factor which may result in external dilution through overbreak, internal dilution through backbreak. It also affect selective loading. All which increase production cost by increasing haulage cost (more waste move to Processing plant), increase mine life (by reducing recovery mill efficiency) and also reduce ore grade automatically reducing ore market value.

Get other factors explain in my blog @ giantminer.blogspot.com

THE SAFE BLASTING AND THE CONTROL BLASTING PRINCIPLE

LEARN ON BLASTING PRINCIPLE AND MECHANICS BEHIND CONTROL BLASTING

INTRODUCTION

From the view of Hoek brown failure graph and failure criterion equation adjustments using the Geological structural index GSI, variation is confirmed to occur in the rock strength parameters due to the effect of Blasting, this was shown in the addition of Rock disturbance factor D to the determination of s,mb and a which are the rock factors constant.

Rock is known to be DIANE (Disvontinous, Anisotropic, Heterogenous and non elastic) according to various claim by rock mechanist like N. Barton among others.

Since rock has such dynamic characteristics, it becomes very difficult to understand the perfect behavior of Explosive energy and the quantity of powder require to cause the breaking and the casting of the rock mass. 

Actually what the  generated during blast need to reflect is change in medium (solid to air, solid to liquid), this is the important of free face. Free face is the region of Freedom or escape of wave from one medium to another. face reflect the traveling wave and cause it to be effective for fracturing.

Check my videos on rock breakage and article on it. For the full content you will enjoy it and understand why Explosive Perform splitting at wall when using control Techniques like presplitting, post splitting, cushion Blasting, empty hole line Blasting. In line hole Blasting, the uncharged holes create Free face to reflect back traveling wave, prevent fracturing and make gas energy in active for explosion at the unmined region.

The presplitting principle also use this, from Konya work in 1980s he develop a constant that explains the charge weight needed to perform the splitting base on the rock strength and the hole spacing.

Actual splitting principle

What happened during splitting is that, the wall boundary is fractured ahead of the main Blasting, therefore creating a wave barrier region which prevent the traveling of the shock wave into the bench face. Actually from Examine 2D software checking, as a Boundary element Method of Numerical design approach for  excavation, the induced stresses at the competent zone of any excavation is low due to the Excavation damage Zone which show a residual stress behavior, from this claim, I come to understand that, the wall of a presplitting mine has low induce stress which contain low stress concentration, and due to this create a change medium for shock wave reflection back to the main Blasting area.

Just as the free face assist in reflecting the shock wave to perform full tensile slabbing in normal Blasting operation, so did the split area does in presplitting region.

Reason for Control Blasting

Mining is a field concern with the use of appreciate method and Technology which support both the safety of the mine and the profitability of the project. Therefore to achieve this and prevent any form of barriers like, rock wall fall, wedge sliding, overbreak beyond design stole width, ground vibration, air blast, rock Burst due to suddenly release of stored strain energy in tensioned rock, noise generation beyond 80-85dB (A), prevention of Fly rock from mine face to safety zone/region among others.

The place of Control Blasting can not be overlooked if a mine will like to work the ore profitably, poor fragmentation result into truck idle time during load, low machine ultilization factor there is the ultilization factor is greater than unity, dilution both internal and external, poor fragmentation with low uniformity index among others.

When the Blasting result is poo, it makes the process operation poor also, it affect all downstream operation from crushing to grinding, to Libration to separation of concentrate from the waste, more cost will be incur on Transportation and more cost in processing and storage..

In Conclusion, Control Blasting operation give assurance of safety and profit. The major problem something lies in the supervision and design of the blast which brings about variation in blast result compare to the expected design work. The bottleneck in Blasting operation is not just the Explosive energy but the pre-planning stage which requires proper plan and operational stage out for good Blast. Above all, Safety is the first goal, let all Blasting operation be done in a safe and secure manner, proper coordination of Explosive handling, ensure the queue discipline of First come first serve (FCFS) Or First in First out (FIFO) is adopted in the magazine to prevent Explosive been deteriorated or expired by passing the shelf life. All unused Explosive materials must be moved from the site before firing, the maximum instantaneous charge must be use to determine the best safety distance to position mine machine to avoid damage due to fly rocks and debris, for the NONEL Blasters, ensure the safety fuse is properly insert and tighten in the cap, never use stone or try use teeth to tighten cap cylinder to the safety fuse, avoid using short length Safety fuse, let the length factor of Safety be at Least Greater than 2.5, do not because of cost, overcut the fuse, all electric Blasting operation must be suspended during cloudy or lightening, test the exploder before using it, Check the current Available and that required to initiate the blast, check the connection using appropriate equipment to avoid current breakage within row or inter row, ensure in hole charges are properly tap and properly steamed with the steam length needed.

Finally, Blasting is a control and safe bombing that is for production, when is produce unsafe and hazardous impacts it becomes disastrous, likewise having Explosive in the wrong hand is a threatening to humanity and the nation, no unauthorized person is expected to be in possession of Explosive and Explosive materials not even the cartoon or a cut of fuse (Explosive Acts).

Therefore, detest from the stealing of Explosive materials from site to sell illegal, it I a criminal offense and punishable under the Explosive and mining Act. Let all mine manager  see to the welfare of there employee to avoid such act and unsafe act.

All activities in the mine must be a team work, let the workers be motivated by providing both financial and non financial motivator for them.

You can learn on:

Abraham Maslow's motivation theory,

Herzberg two factor motivation theory,

McGregor Theory X and Theory Y for employee motivation and finally the carrot and stick approach to avoid negligence in work..

The better the leadership of the minig operation, the good the output result. Set a control measure and performance standard for all blasting operation and supervise the Control both open and close free reins.

Mining operation is the best way to keep humanity alive and kicking, we produce the material for all production, no mining no cars, no manufacturing, no innovation.

Let mine the earth safely.

About the writer:

Giant Miner is a fresh graduate of Federal University of Technology Akure, He graduate from the department of Mining Engineering and Engineering Technology.

He is ready for internship in any mining company and wish to contribute to any mining operation both in Nigeria and outside Nigeria.

Reach Giant Miner on:

WhatsApp contact:+2347031018600