Consequent to a previous article, we have been asked to discuss briefly the financial implications of poor drilling. When we talk about drill and blast, the conversation usually leans towards explosives and their application, while the drilling component gets far less attention. Many operations still track drilling the way they always have: cost per metre drilled. It’s neat. It’s familiar, yet it’s dangerously incomplete. Drilling doesn’t exist in isolation. Every metre drilled sets the conditions for blast performance, downstream productivity, and ultimately profitability. When drilling is optimised solely to reduce the drill contractor’s invoice, costs are often pushed—quietly but significantly—into every stage that follows. That’s why Total Drilling Cost matters far more than drill cost alone. What Is TDC (Really)? Total drilling cost is not just: Drill contractor rates Consumables Maintenance Fuel and labour It also includes the consequences of drilling quality: Hole deviation and collar accuracy Burden and spacing variability Sub-drill consistency Redrilling Misfires and blast inefficiencies Poor fragmentation impacting loading, hauling,crushing Increased dilution, losses, or downstream bottlenecks A cheap metre drilled badly is one of the most expensive metres you’ll ever mine. The False Economy of “Cheap Drilling” We've seen this pattern repeatedly: Drill rates are pushed down Penetration rate becomes the primary KPI QA/QC is reduced Operators are incentivised on metres, not quality On paper, drilling cost improves. In reality: Blast performance becomes inconsistent Powder factor increases to compensate Dig rates slow Crusher throughput drops Maintenance costs rise Reconciliation gaps widen The operation spends far more trying to fix the blast than it saved on drilling. Shifting the Conversation: From Cost to Value High-performing operations look at drilling differently: Cost per effective hole, not cost per metre Accuracy compliance, not production metres Drill-to-blast alignment, not isolated KPIs System performance, not departmental optimisation They understand that drilling is a precision activity, not a volume race. What to Measure Instead If you want to understand your true drilling cost, ask: How much rework are we carrying due to poor hole placement? What is the variance between planned and achieved burden? How often do blast designs require modification to compensate for drilling? What is the downstream cost of poor fragmentation? Are drill KPIs aligned with blast outcomes—or working against them? These answers rarely sit in one department. Final Thought Drilling is the first act in value creation. Get it right, and everything downstream becomes easier. Get it wrong, and no amount of blasting “optimisation” will save you. If you’re still judging drilling purely on cost per metre, you’re likely paying far more than you think.

Geotechnical focus: Core drilling and sampling standards are about controlling damage, not just drilling depth: correct core barrel and bit selection (HQ/NQ/T2), low-disturbance drilling parameters, full core recovery, proper orientation, and disciplined handling and boxing. Poor practice shows up immediately as low recovery, broken core, and unreliable RQD. Mineral exploration focus: In mineral exploration, core drilling standards aim to preserve geology and structure: appropriate barrel size, stable drilling parameters, accurate core orientation, and strict core handling and logging. Recovery quality directly affects structural interpretation, grade control, and confidence in resource models.

As perfuratrizes são equipamentos utilizados para realizar furos em rochas, com o objetivo principal de permitir o desmonte com explosivos, investigação geológica ou instalação de suportes. São fundamentais tanto na mineração a céu aberto quanto na subterrânea. Principais Funções 1 Perfuração para Desmonte Realizam furos no maciço rochoso. Esses furos são carregados com explosivos. Após a detonação, a rocha fragmentada é carregada por escavadeiras. 2 Perfuração para Pesquisa Geológica Coleta de testemunhos (sondagens). Determinação de teor, estrutura e profundidade do minério. 3-Perfuração para Estabilização Instalação de tirantes e chumbadores. Controle geotécnico em taludes e galerias. Tipos de Perfuratrizes na Mineração Perfuratrizes Rotativas Usadas principalmente em minas a céu aberto. Indicadas para furos de grande diâmetro. Muito comuns em minas de ferro. Perfuratrizes DTH (Down-The-Hole) Martelo funciona no fundo do furo. Alta eficiência em rochas duras. Produzem furos mais retos e precisos. Perfuratrizes Top Hammer Martelo hidráulico fica na parte superior. Ideais para furos menores e médios. Jumbo de Perfuração (Subterrânea) Equipamento montado sobre chassis. Muito usado em túneis e minas subterrâneas. Vantagens Alta precisão na perfuração Maior produtividade Redução de custos com explosivos Melhor fragmentação da rocha Segurança operacional. Importância no Ciclo Mineiro A perfuração é a primeira etapa do desmonte de rochas. Se for mal executada, pode causar: - Má fragmentação - Aumento do custo de britagem - Perda de produtividade - Riscos de segurança.

1️⃣ Diamond Core Drilling (HQ/NQ/BQ) Produces intact core — the gold standard. If you want RQD, fractures, UCS, structure, or lab tests, this is your method. → Best for: Tunnels, dams, slopes, deep exploration. 2️⃣ Reverse Circulation (RC) Drilling Fast, efficient, and cost-effective. Delivers rock chips, not core. Brilliant for quick decisions in hard rock. → Best for: Reconnaissance, orebody delineation, grade control. 3️⃣ Down-The-Hole (DTH) Hammer A pneumatic hammer breaks very hard rock with ease. High penetration, low cost, no core. → Best for: Hard volcanics, blasting holes, geotechnical boreholes. 4️⃣ Top Hammer / Percussive Drilling (Jackleg, Stopper, Jumbo) High-frequency drilling where mobility matters most. If you’ve been underground, you’ve heard it before you saw it. → Best for: Underground headings, stopes, tunnel blasting. 5️⃣ Rotary Air Drilling (Tri-cone Bit) Fast and cheap. Produces cuttings only. Love it for dry, competent rock. → Best for: Recon drilling, pre-collar holes, shallow investigations. 6️⃣ Rotary Mud Drilling (in Fractured Rock) When the rock mass is weak, crushed, or sheared — mud keeps the hole open. Not ideal for core, but perfect for stability. → Best for: Shear zones, faulted rock, geotechnical instrument holes. 7️⃣ Horizontal / Directional Core Drilling When you need rock data in a specific direction — especially in tunnels or dams. Game-changer for proactive hazard detection. → Best for: Tunnel face probing, slope anchors, deep foundations. 8️⃣ Sonic Drilling (Moderately Hard Rock) Vibration-assisted advance that preserves core in weathered rock where diamond drilling struggles. → Best for: Rock-soil transitions, altered rock.

Core drilling is one of the most fundamental and reliable techniques in mineral exploration. It serves as a direct method of obtaining subsurface samples that provide a continuous record of the geological formations beneath the surface. The cylindrical samples, known as cores, give geologists valuable insights into the composition, texture, and structure of rocks, helping to identify and evaluate potential mineral deposits. The process typically begins with the use of a diamond-tipped drill bit, which cuts through various layers of rock while preserving the core inside a hollow tube. These cores are then carefully extracted, logged, photographed, and analyzed in laboratories. Through this detailed examination, geologists can determine the type, grade, and distribution of minerals present — essential data for accurate resource estimation and feasibility studies. Unlike other drilling methods, such as reverse circulation (RC) drilling, core drilling provides more detailed geological information because it maintains the integrity of the rock sample. This makes it particularly valuable for structural analysis, stratigraphic interpretation, and geotechnical assessments. In modern exploration, core drilling rigs are equipped with advanced hydraulic and digital control systems that allow for greater depth accuracy, improved safety, and better data acquisition. Furthermore, precise core orientation techniques enable geologists to understand the true position of geological structures, such as faults, folds, and veins, which are critical in mine design and planning. It is also worth emphasizing that core handling and preservation are key aspects of successful exploration. Improper labeling, contamination, or poor storage can lead to data loss and misinterpretation. Therefore, maintaining a standardized core logging and storage procedure is essential for ensuring data reliability.

Key Performance Indicators (KPIs) for Optimisation of Drilling & Blasting operation in Opencast Mines 1. Technical KPIs Monitor powder factor optimization Track fragmentation size distribution Measure blast-induced damage levels Assess drilling accuracy and precision Evaluate explosive utilization efficiency Monitor equipment productivity rates 2. Safety and Environmental KPIs Track safety incident rates Monitor vibration and noise compliance Assess air quality impact levels Measure flyrock occurrence frequency Document environmental compliance status Record community feedback and concerns Key performance indicators (KPIs) for optimization of drilling and blasting include * *Rate of Penetration (ROP) ** , Powder Factor, Rock Fragmentation , Equipment Utilization Cycle Time of Shovel Throughput of Crushers , Drilling and Blasting Costs, Ground Vibration, Bit Life, and Safety Incidents. These KPIs provide quantifiable measures to evaluate drilling effectiveness, blast performance, operational efficiency, and safety, facilitating continuous improvement and alignment with overall mine goals. Drilling Performance KPIs Rate of Penetration (ROP): Measures the speed at which the drilling unit can penetrate the rock. Penetration Rate (Depth per Hour): Assesses the productivity of the drilling unit over time. Bit Life: Tracks the durability and performance of drill bits. Equipment Utilization: Measures the effective working hours of drilling units against their total working hours. Drilling Costs per Foot: Evaluates the cost-effectiveness of drilling operations. Blasting Performance KPIs Powder Factor: The amount of explosive used per volume of rock blasted, used to optimize blast design. Rock Fragmentation: The size distribution of the blasted rock, a critical factor for downstream processes like crushing and milling. Flyrock: Measures the distance and potential danger of rocks thrown from the blast site. Back Break: Indicates the extent of rock damage beyond the intended blast perimeter. Air-Overpressure (AOp): Measures the force of the air blast, which can impact surrounding areas. Safety & Environmental KPIs Ground Vibration: Tracks the level of ground shaking caused by the blast, which is critical for maintaining structural integrity and minimizing environmental impact. Safety Incidents: The number of safety-related incidents during drilling and blasting operations. Overall Operational KPIs Cycle Time Optimization: Focuses on reducing the overall time taken for drilling and blasting cycles. Volume Blasted: Measures the total volume of rock successfully blasted within a given period. Energy and Environmental Metrics: Includes energy consumption and other environmental impacts to ensure sustainable operations.

Reverse Circulation (RC) Drilling Rig: is a widely used technique and quick drilling method used in mineral exploration and method of testing the size, grade, and geology of mineral deposits before mining starts, where compressed air is used to push rock cuttings through the inner tubes of drill rods to the surface. This allows for the collection of fine rock samples for analysis and providing geological information at regular intervals . RC Rig Functions: Drilling: Dual-tube drill rods (inner and outer) are pushed into the ground. Air Delivery: Compressed air is pumped down through the space between the tubes. Cuttings Ejection: Compressed air rises, carrying rock cuttings (from drilling) through the inner tube of the drill rods. Sample Collection: Rock cuttings are separated from the air via a cyclone system, and samples are collected for analysis. RC Rig Components: Dual-tube drill rods: These are the tubes that descend into the drilling rig. Drill Hammer: This is the tool that breaks up the rock. Drill bit : Typically made from hardened steel or tungsten carbide, designed to crush and break rock. Air Pump: Provides the compressed air needed to propel the rock cuttings. Cyclone System: Separates the rock cuttings from the air. The importance of reverse circulation drilling (RC rig): Sample extraction: Fine samples of rock can be extracted for analysis. Mineral locating: Samples can be used to locate minerals such as gold and other metals. Deep penetration: can reach significant depths, enhancing exploration capabilities. Reverse circulation drilling: Air is sent through the space between the tubes and forces rock pieces through the inner tube. The most important informations we should collect while working on the rigs are : - quick description of ( lithology, alteration, associated minerals appearance ). - starts and ends of our expected mineralised zones approximately. - split and prepare samples and its weight . - Resource Assessment : Aids in quantifying mineral resources estimation. - faster drilling rates: general quicker than diamond drilling, making it cost-effective for exploration. Note : The drilling rate different by the rock unites and its hardness. In short, an RC rig is an effective tool in mineral exploration, as it allows accurate rock samples to be extracted and analyzed and faster and more economical and less cost than other drilling methods .

Doing a detailed review of underground stope drill and blast performance can easily identify the main factors behind stope performances against designs. It is critical to review both technical and operational drill & blast aspects, identify issues and provide recommendations however it's more better to implement the recommendations to see improvements in the stope recovery. Below is a detailed stope drill and blast review I did and the summary and recommendations provided. Simple things that add up to an overall stope performance. ________________________________________________________________________ SUMMARY: • From the reviews done so far there is minimal to no issues identified in the technical design perspective in terms of drill and blast design parameters. • Void ratio was tight with 0.955 against site specific 0.95 after applying 30% swell factor. • From the LPU data, 5 slot holes were significantly undercharged. Prep returns & Simba cleanout plods show that these holes were prepped. There is possibility of slot bridge or significant slot underbreak expected as we do not have a breakthrough void yet at this stage. • Logger data and charge returns show that the correct number of dets were charged with correct delays assigned and correct number of primers charged as per the plan. There is no return to show that the primers were staggered as per the charge plan. • Total of 15.7t emulsion used. 14.8t emulsion charged into blast holes against a design of 14.2t. RECOMMENDATIONS: 1. D&B Engineers to check new void ratio using the CMS after undercuts taken to see if the downhole shot will be accommodated by the usable voids available. 2. D&B Engineers to notify slot location and the slot holes to the charge crews and stick to the approved charge plan. 3. Charge crews must be aware of how critical the slot is and notify engineers of any issues confronted during charging and assigning delays to the slot holes. This also includes other blast holes. 4. D&B Engineers to check LPU Data to make sure charging was done according to the charge plan issued. 5. LPU Operator to use LPU Hole ID same as Design Hole ID during charging to make it easier to compare ascharged LPU data against design data. 6. Shots greater than 20m height to be left for at least 3 hours (3hrs to confirm?) after charging to allow gasing of emulsion to the designed uncharged collars. 7. D&B Engineers to maintain reviewing of prep returns prior to finalizing charge plans.

For so many drill and blast professionals, its not the "Drill & Blast" department but rather the "Drill & Blame" department. Where "no news is good news". If there is poor dig or other issues you have half the minesite pointing fingers and making noise. When the blast works well its crickets, while patting the production team on the back for nailing dig productivity. A shoutout for the career professionals that stick with it, that are passionate about D&B and know how much goes into getting it right. And praise to the managers who recognise the importance of good D&B; ensuring their D&B professionals are enabled to success, while being recognised for the good blasts and learning from those that need improvement. What have you seen work well to fix the blame culture, to retain our good people and achieve great D&B ?

Hablemos de una confusión GIGANTE que escucho muy seguido en la minería, algo tan básico que se dan por sentado... Muchos —y te sorprendería cuántos— cree que esa herramienta, cuando la paras a cierta profundidad, toma su medición exactamente donde esta la camara, pero realmente es asi? Imagina que, metes un lápiz rígido y cortito dentro del barreno. Esa herramienta de survey o medición es ese lápiz en ese pedacito de hoyo y el borrador es la camara. Lo que hace la herramienta (el lápiz) en cada lugar donde la detienes, es medir la DIRECCIÓN a la que está apuntando ese lápiz en ese punto Te dice dos cosas clave: 1.- Qué tan inclinado está ese lápiz hacia abajo (eso es la famosa Inclinación). 2.- Hacia dónde apunta ese lápiz en el mapa (eso es el Azimut, la dirección horizontal). O sea, te da la DIRECCIÓN del barreno en ese punto, Y aquí viene la clave que quiero que te lleves hoy (y que confunde mucho): Si la herramienta (el lápiz rígido) tiene un tamaño, digamos de 1 o 2 metros… ¿Importa si el sensor que "lee" la dirección (el borrado del lápiz) está al principio, en medio o al final de ese lápiz? ¿Cambia la medición si el sensor está 30 centímetros más arriba o más abajo dentro de la misma herramienta? ¡Para medir la dirección de ese lápiz, NO importa ni tantito! La herramienta es ese objeto rígido que se alinea con ese tramo corto de barreno. Lo que mide es la dirección de TODO ese tramo. No es un truco de magia ni geometría de otro planeta. Es la simple verdad: un objeto recto apunta en una dirección, y esa dirección es la misma en todos sus puntos. Entender esto — que la ubicación interna del sensor no cambia esa lectura direccional— es el primer escalón fundamental. Es como aprender el ABC del survey (trayectoria de barrenos, mediciones, ect, fotos, shots). Por ahora, quédate con esto: En cada parada, mide la DIRECCIÓN de un pedacito de hoyo (con ángulos). Entender esto no es solo un detalle técnico. Es lo que separa un modelo geológico preciso… de una interpretación equivocada que cuesta millones. No midas puntos. Mide direcciones. Piensa en segmentos. Modela con intención. ¿Ya lo aplicas así en tus proyectos? ¿O todavía hay dudas en tu equipo?