Copper Exploration and Development
How are Copper deposits found and developed?
Copper mineral exploration is the principal method for finding the world's copper deposits. This is the domain of exploration geologists and the key phases of copper exploration and deposit discovery are:
•Area selection: Geologists apply geologic theories behind regional or large scale geology models to predict possible occurrences of copper deposits and the genesis of their formation. Once prospective areas are screened, land positions are sought by application for exploration rights, fee simple land purchases, or numerous forms of joint ventures or partnerships with land or rights holders.
•Target definition: Once prospective land and exploration rights have been acquired, geologists refine the prospective land, to delineate drill targets in areas with the highest probability of discovering economic copper deposits. Geologists use a number of tools to aid in this target selection. These tools can be broadly categorized as:
?Geological rock sampling and rock mapping: Geologists collect surface level rock samples and map rock structures to better understand regional and local geology conducive to copper deposits.
?Geophysics: Since copper is highly conductive, geophysical methods can be used to measure conductivity, resistivity and magnetism. This allows the explorationist to make a view on sub surface structures and detect anomalies of conductive suphide copper minerals and resistive host rocks
?Geochemstry: Geochemical analysis involves the use of the analysis of chemistry of sediments to target potentially mineralised zones that have surface level chemistry "signatures". Geochemical data is investigated for anomalies (single or multiple elements) that may be related to the presence of sub surface copper mineralisation
?Remote sensing: Often aerial photography and satellite imagery is used in the analysis of land structures that may indicate conditions favourable to the formation of copper deposits.
•Resource evaluation Resource evaluation is undertaken to quantify the grade and tonnage of a copper deposit and this is achieved by drilling . Drill holes are carefully planned on anomalies identified in the target selection phase. Once a drill hole has been completed, the drill core is removed so that subsurface rock can be assayed for grade and the rock types and mineralization can be recorded and mapped. The ultimate aim is to generate a density of drilling sufficient to satisfy the statutory standards of a mineral resource in terms of volumes (tonnage) and copper metal content (grade). There are several international recognized codes that define what is required to classify drill data as an ore resource.
•Reserve evaluation Reserve definition is undertaken to convert a copper mineral resource into a copper reserve, which has a higher degree of certainty to be extracted economically. The process is similar to resource evaluation, except more intensive drilling and engineering, aimed at statistically quantifying the grade continuity and volume (tonnage) of ore. This process involves cost estimates and takes into account the mining, processing and extractability characteristics of the copper mineralisation, and generates bulk samples for metallurgical testwork, involving crushability, floatability and other ore recovery parameters necessary for economic extraction.
•Feasibility studies A feasibility study is a study undertaken to determine and document whether a copper deposit is economically viable to become a mining operation. The study involves detailed engineering, permitting, and environmental, social and cost analysis. The results of this study are used to make a decision whether to proceed with the project, and are often used to evaluate whether financing will be available to construct a mine. Based on a positive decision to proceed, mining companies, together with engineering, procurement and construction contractors build the mine operation and prepare to extract the copper ore.
