The Minto mine uses conventional open pit mining techniques and equipment for all of its ore and waste extraction. Blast holes are drilled out in accordance to issued designs. Explosives are loaded into blast holes and the rock is blasted to manageable rock sizes. Shovels are used to load haul trucks that will transport the rock to its intended destination. Ore is hauled directly to the crusher feeding the mill or to temporary stockpiles according to the graded characteristics of the ore. Waste rock is transported to waste rock storage piles.
The ore is fed into the primary crusher and the Semi-Autogenous Grinding (SAG) mill where it is crushed and grind to reduce particle size. The ore is enters a number of flotation circuits where copper, gold and silver minerals are separated out from other minerals. The concentrated ore is thickened and de-watered using thickeners and filters. The concentrate is moved to the concentrated storage shed where it is loaded onto trucks and transported off site.
Production and Processing
In 2011 the Minto Mine produced 37.1 million pounds of copper in concentrates. Current capacity is 3,600 tonnes per day and additional deposits are scheduled for development to extend the mine life.
Minto Explorations will be seeking amendments to its current operating permits from the Yukon government and Water Board in order to increase production and expand mining operations into the newly identified ore deposits (Phase V and VI).
The process facility built at the Minto Mine utilizes a conventional circuit comprised of a crusher, SAG and ball mills for grinding, and flotation to produce concentrates that are filtered and stockpiled in a storage facility for shipping to the port of Skagway, Alaska, for export overseas. A filtered tailings system is being used to mitigate reclamation costs by allowing dry stacking of tailings.
The Minto concentrator initiated production in May 2007 with a design daily production rate of 1,563 tonnes per day. Since this time, Minto has expanded its operations significantly with the discovery of nine copper deposits within sixyears. A Phase II mill expansion was completed in 2008 increasing throughput to 2,400 tonnes per day. The plant throughput was subsequently increased to 3,200 tonnes per operating day in 2009 through improvements the process plant.
The Phase VI Pre-Feasibility study extends Minto's mine life to 2022 with an average of 40 million pounds of copper per year.