Geological Exploration for Lithium

Geological Exploration for Lithium

Subject: Geography

Section: Economic Geography

Concept:

• The Geological Survey of India (GSI) has categorized the recent discovery of lithium resources in preliminary exploration, called the G3 stage.
• According to The United Nations Framework Classification for Resources (UNFC), there are four stages of exploration for any mineral deposit: reconnaissance (G4), preliminary exploration (G3), general exploration (G2), and detailed exploration (G1).

United Nations Framework Classification (UNFC):

• The United Nations Framework Classification for Resources (UNFC) is a resource project-based and principles-based classification system for defining the environmental-socio-economic viability and technical feasibility of projects to develop resources.
• UNFC provides a consistent framework to describe the level of confidence of the future quantities produced by the project.
• It is a universally applicable scheme for classifying/evaluating energy and mineral reserves/resources.
• It was adopted in 2004 by the United Nations Economic Commission of Europe (UNECE).
• The UNFC consists of a 3-dimensional system with the following three axes:
• The UNFC is a three-digit code-based system wherein:
  • First digit represents economic viability axis,
  • Second digit represent feasibility axis
  • Third digit represent geologic axis
• Each of these axes has further codes in decreasing order.

E Axis:

• The degree of economic viability (economic or potentially economic or intrinsically economic) is assessed in the course of prefeasibility and feasibility studies.
• A prefeasibility study provides a preliminary assessment with a lower level of accuracy than that of a feasibility study, by which economic viability is assessed in detail.
• The Economic viability has codes 1, 2 and 3 in decreasing order.

F Axis:

• Feasibility assessment studies form an essential part of the process of assessing a mining project.
• The typical successive stages of feasibility assessment i.e., geological study as initial stage followed by prefeasibility study and feasibility study/mining report are well defined.
• The feasibility assessment has codes 1, 2 and 3.

G Axis:

• Geological Assessment, which is more or less like the classification as per ISP adopted by GSI and other agencies in India.
• The process of geological assessment is generally conducted in stages of increasing details.
• The typical successive stages of geological investigation i. reconnaissance, prospecting, general exploration and detailed exploration, generate resource data with clearly defined degrees of geological assurance.
• The mineral extraction process typically begins with the G4 stage.
• These four stages are therefore used as geological assessment categories in the classification.
• The geological assessment has 4 codes i.e.
  • Detailed Exploration (G1)
  • General Exploration (G3)
  • Preliminary Exploration (G3)
  • Reconnaissance (G4)
• The G3 stage is further categorised into a six-step process to extract Lithium from Salt-flat brines or Mineral ores.
  • Stage 1: Geological Surveys: Mapping on a more extensive scale and linking prepared maps with a top grid. Assessment of lithology, structure, surface mineralisation, analysis of old workings etc.
  • Stage 2: Perform Geochemical sampling rock type wise, soil survey.
  • Stage 3: Detailed ground geophysical work and borehole logging.
  • Stage 4: Check the technicality of pits/trench to explore the mineralised zone and drill borehole spacing
  • Stage 5: Sampling for litho geochemical from a well-known section, pit/trench and core sample
  • Stage 6: Petrographic and mineralogical studies: the combined study of rocks in thin sections and the chemistry, crystal structure and physical properties of the mineral constituents of rocks.
• According to the Indian Bureau of Mines (IBM), apart from the thorough examination of the above-mentioned geological axis, the proposal to mine minerals also needs to be assessed from a feasibility point of view along with the prospects of economic viability.