Drilling in mining is executing bores in soil or rock, and sample/core, product generated in drilling, provides information to the region surveyed. It is a very significant stage for projects in civil construction, hydrology, mining or geotechnics, for instance.
Shall we learn a little more on Drilling in mining Technique use?
Drilling in Mining
Each technique is associated with material objective and type to be assessed. Usually, more than one drilling type is used in projects, thus different information can be achieved in land surveyed.
In mining, drilling methods can be applied in the following stages:
- Mineral Survey (Greenfield projects), when geologists, engineers and technicians assess a deposit feasibility;
- During mine extraction, to enrich the knowledge about the about and set extraction continuity;
- Exploration stage (Brownfield projects), that is designed to expand current undertaking expansion, that is, finding new ore occurrences next to current company exploration;
Cores and samples collected in drilling performed in a project provide essential information to mineral resource calculation, thus, they impact decision making directly.
Drilling types indicated in mining
There are several drilling types, however some of them are more indicated to mining project, including: percussion drilling and rotary drilling.
Also known as SPT (Standard Penetration Test) drilling, it is a soil survey method which drilling progress is performed through auger or washing, and a sampler driving is used to measure penetration strength indexes, achieve samples, assess water level and execute several assays in situ.
Standard Penetration Test (SPT) is executed in percussion drilling to achieve soil penetration strength indexes. It is set by the strike number corresponding to 30 cm drilling of standard sampler, upon initial 15 cm drilling.
In this method, samples are collected meter by meter, enabling tactile and visual analysis of subsoil layers.
Source: APL Engenharia
As Percussion drilling is used in mining projects, it is expected that the following information is used:
- Water table level;
- Rock type;
- Soil stratigraphy;
- Penetration Strength Index.
One of Percussion Drilling main advantages is low cost, enabling higher sample number collection.
- It is not possible to use this method to drill inclined territories and soils;
- Harder rock and earth low performance;
- It has higher sample contamination probability;
- Petrographic identifications (texture, composition and structure) are harder to be acknowledged.
In cases it is required to use rotary method and switch to percussion method, drilling is called ‘mixed’.
It is a motomechanized set use designed to drill rocky massives and sample achievement with cylindrical shape, core calls (continuous samples in cylindrical shape, with associated metering indication).
This technique is used to survey aspects that are not possible to be totally inspected by percussion drilling technique. Sample drilling and collection is performed through rotary probes, equipped with rods, cut crown and sampler barrel.
Through rotary drilling, it is possible to achieve great subsoil depths. In mineral sector, this is the most widely known and used method.
Rotary Drilling Core. Source: Internal database
Rotary drilling Advantages:
- It is possible to perform drilling with inclination angles;
- It accepts water loss assay in rocky massive lands;
- It preserves drilled material integrity;
- It enables achieving complete geological record, so that rock structures and textures can be assessed.
As Rotary drilling is used, it is expected that the following information is used:
- Existing soil type;
- Rock type;
- Quality index found in rock structure;
- Foliation, among other analyses.
Prilling is an essential practice in mineral sector, through it, it is possible to gather lots of information that can set a project creation, continuity and completion. Thus, it has to be executed responsibly and supported by experienced professionals.
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Drilling Manual – ABGE 2013
Apl Engenharia. https://blog.apl.eng.br/sondagem-a-percussao-conheca-e-entenda-os-procedimentos-executivos/ and https://blog.apl.eng.br/sondagem-rotativa-aqui-esta-tudo-o-que-voce-precisa-saber-sobre-o-assunto/