MMPE 290 Introduction to Mining & Mineral Process Engineering Mining Geology and Exploration

 How much metal is available?  What is a mineral? What is ore?  How do ore deposits form?  Mining exploration methods  Role of exploration in mining  Case histories Mining Geology and Exploration

Note for comparison: Silicon 28% Oxygen 46% Economically Important Metal Concentrations in Earth’s Crust

A solid naturally-occurring compound having a definite chemical composition Examples: quartz - SiO 2 (an oxide) hematite - Fe 2 O 3 (another oxide) covelite - CuS (a sulphide) What is a mineral?

An occurrence of minerals or metals in sufficiently high concentration to be profitable to mine and process using current technology and under current economic conditions. What is an ore deposit?

What is ore grade? ·Weight percentage (base metals) ·Grams/tonne or oz/ton (precious metals) Ore grade is the concentration of economic mineral or metal in an ore deposit.

Economically Important Metals Typical Grades of Ore Deposits

What does it take to be an ore deposit?

As magma cools, more abundant metals (silicon, aluminum) deposit first Solidification of magma releases water - a hydrothermal solution Minerals precipitate from hydrothermal solution and deposit in cracks or veins in rock Hydrothermal Ore Deposits

Concentration of minerals caused by high temperatures and pressures near intrusions Examples: Lead-zinc deposits in southeast B.C. Diamonds Garnets Metamorphic Ore Deposits

Hydrothermal and Metamorphic Ore Deposits Intrusion Hydrothermal solutions entering veins in rocks Geyser or hot spring Ore deposit Alteration of rocks by heat and pressure zoning

Deposition of dense, resistant minerals in streams, lakes etc (Alluvial Deposits), e.g. Placer gold Precipitation of minerals from ancient oceans (Evaporite Deposits), e.g. Potash and salt deposits Accumulation, burial and petrification of vegetation, e.g. Coal Deposits. Sedimentary Ore Deposits

Exploration Methods ·Remote sensing ·Geological mapping ·Geophysical surveys ·Geochemical surveys ·Bulk sampling ·Drilling (core or destructive)

Airborne Geophysics Helicopter Bush Cable “Bird”

GEOPHYSICAL METHODS

Geochemical Anomalies

DIAMOND DRILL

HOLE SIZES

SURFACE SET DIAMOND DRILL CORE BIT AND REAMING SHELL

Senior Mining Company Exploration Expenditures Total: $817.7M

Junior Mining Company Exploration Expenditures Total: $262.2M

Role of Exploration pEach ton of ore mined must be replaced with another ton to continue business. pThe alternative to exploration is acquisition of mining properties. pExploration has a high failure rate, but this should not affect a diversified mining company. pExploration costs are tax-deductible.

Diamonds in Canada? Diamonds are formed at high pressure deep in the earth and transported to surface in kimberlite pipes Other minerals also formed if pressures high enough - indicator minerals Indicator minerals are mobile and easily transported by erosion.

Direction of glacier flow Indicator minerals Kimberlite pipe An eroded kimberlite pipe

Lac de Gras

The Ekati Mine

Recommended Reading Fire into Ice Charles Fipke and the Great Diamond Hunt by Vernon Frolick Raincoast Press

Formed million years ago by hydrothermal activity in sedimentary rocks Part of a large mineralized zone extending into Mexico and Central America Carlin, Bootstrap, Cortez, Gold Acres Some deposits low grade but can now be processed using heap leach technology Nevada Gold

Volcanic and igneous activity in Andes produces a variety of rich mineral deposits Minerals are exposed at or very near the surface - leads to oxidation requiring different kinds of mineral processing Transport of mineral products, power and water supply a concern in high Andes South American Ore Deposits