Lec 2 - Mine Exploration Flashcards
What are the steps in exploration?
- select potential area
- collect regional data and define local target area
- reconnaissance explo
- geophysical and geochemical exploration
- reconnaissance and bracket drilling
- ore discover
Potential areas
- areas of known production
- areas of known occurence
- favorable conditions for deposition
Collect regional data and define local target area:
- historical data, state surveys, archives
- univ research programs
- compamy reports
Types of Remote Sensing
- DEM - Digital Elevation Model
- TM - Landsat Thematic Mapper
- ASTER - Advanced Spaceborne Thermal Emission and Reflection
- Hyperspectral Remote Sensing
- NOAA-AVHR - National Oceanic And Atmospheric Administration- Advanced Very High Resolution Radiometer
The science of remotely acquiring, processing and interpreting spectral information about the earth’s surface and recording interaction between matter and electromagnetic energy
Remote Sensing
- A way to gather and present geologic data
- shows how rock and soil on the earths surface is distributed
- predict what is below the earth’s surface
Geologic Mapping
Things you need in Geological Mapping
- field notebooks
- rock hammer
- hand lens
- pocket knife
- magnet
- clipboard
- pencils
- scale protacters
- tape measure
- camera
- gps
- brunton compass
- radiograph type pens
What are the things you need to identify during geol mapping
- rock units and relationship
- host rock characteristics
- structures
- alteration
- gangue minerals
- ore mineralogy
- rock sampling
It helps narrows a region to a smaller area of specific interest
Reconnaissance
Scale of a detailed map
1:10,000 or 1:12,000
Geochemical Sampling
- ground water
- surface water
- stream sediments
- soils
- biological
- ore samples
2 types of sampling program
- Reconnaissance
2. Field Inspection
Surface grab sampling over all exposures of gravel, few seismic cross section, geobotanical study, and survey for old workings
Field Inspection
Lab Analysis
- host rock characteristics
- ore mineralogy
- alteration mineralogy
- age dating
- fluid inclusion
- isotope geochemistry
Process whereby rigs or hand operated tools are used to make holes to intercept an ore body, and is the ultimate stage in exploration
Drilling
Purposes of drilling
- to define the ore body at depth
- to access ground stability
- to estimate the tonnage and grade of a discovered minera deposit
- to determine presence or absence of ore bodies, veins or other type of mineral deposit
Common types of drilling
- Auger Drilling
- Diamond core drilling
- reverse-circulation drilling
- hydraulc rotary drilling
Uses a helical screw called “fighting” which acts as a conveyor to remove drilled out material
Auger Drilling -low cost -fast rate penetration -free of contaminating fluid But... -effective only for unconsolidated material -slower than other methods -heavy equipments
Utilizes a diamond drilling bit to obtain a cylindrical core of rock (core sample)
Diamond Core Drilling -quick and can be done anywhere -very little dust -provide more geological info -precise and has minimal damage to envi But.... -noise -limited size of drill bits
A method of drilling which uses dual wall drill rods that consists of an outer drill rod with an inner tube. These hallow inner tubes allow the drill cuttings to be transported back to the surface in a continuous steady flow
Reverse-Circulation Drilling
- drilling cost can be reduced by fast rate of penetration
-requires less water
-quick sample retrieval
But….
-the samples retrived has less geological relevance
Employs a sharp rotational drill bit to bore into the crust; typically uses tricone bits
Hydraulical Rotary Drilling
-can drill greater depths than diamond drilling
But…..
-more expensive
-has bigger footprint than diamond drilling
High pressure safety valve system at the top of the well head which stops uncontrolled fluid/gas flow in the well bore
Blowout Preventor (BOP)
