From Exploration to Development
The Development Process for Nonferrous Metallic Minerals
The objective of a mineral exploration company is to discover a new and economically-feasible mineral deposit. One example is to start at a known deposit, which is too small to be economically feasible, and discover more resources that add to the deposit size. There are no nonferrous metallic mineral mines in Minnesota, but there are development projects. Listed below are general phases necessary to develop a nonferrous metallic mineral mine after exploration has discovered some mineralization:
- Discovering a mineral prospect: Finding mineralization in a few drill cores, no matter the richness, does not make a mineral deposit. At this point, the site of mineralization would be called a mineral prospect.
- Evaluation drilling: After initial favorable results, a time-consuming (multi-year) and expensive (millions of dollars) program of follow-up core drilling and assaying must be conducted to prove out the areal extent, thickness, depth below surface, and concentration of metals (grade) before it can qualify as a mineral deposit.
- Preliminary economic assessment: Whether this mineral deposit can be economically mined will require that the value of the defined ore body be compared to the labor and capital costs related to building the mine and processing facilities, mining and transporting the ore, crushing and processing the ore, recovering the metals, developing sound environmental mitigation, financial assurance for the permit, and planning for mine closure.
- Environmental baseline testing: To properly evaluate the costs listed above, environmental baseline testing must be conducted and a mitigation plan developed.
- Metallurgical testing: Metallurgical testing must be done to determine whether the metals can be separated from the particular type of rock, and at what cost.
- Economic feasibility study: A complete economic feasibility study will incorporate all steps needed for the overall plan from the start of mining to the point of product sales to mine closure.
- Capital investment: Raising capital for building the mine and facilities, which is usually in the range of hundreds of millions to billions of dollars.
- Environmental review: Environmental Assessment Worksheets and/or Environmental Impact Statements are required for new mining proposals and are often required for expansions or substantial changes to existing operations as stated in Minnesota Rules, part 4410.4300, subparts 11-12 & Minnesota Rules, part 4410.4400, subparts 8-9. These rules were adopted under the Minnesota Environmental Policy Act, MN Statute 116D. See MN DNR's Mineland Reclamation webpage for more information.
- Permitting: After Environmental Assessment Worksheets (EAW) and/or Environmental Impact Statements (EIS or SEIS) have been deemed adequate the company can submit applications for a permit to mine. Permit requirements for nonferrous mines are described in the Mineland Reclamation Rules Chapters 6130, 6131, and 6132 respectively. Again, please see MN DNR's Mineland Reclamation webpage for more information on this subject.
There is a long list of possible reasons, such as a drop in the metal price, as to why a mineral deposit discovery may not be developed into a mine.
- State regulations for exploration drilling
- State regulations related to environmental review and permitting new mines
- See a map known metallic mineral deposits
- *View the PowerPoint titled 'Metallic Mineral Exploration in Minnesota: Typical Exploration Activities'
- Learn about typical exploration steps for nonferrous metallic minerals
*The PDF includes embedded 'speaker notes' with additional information for select slides. The speaker notes can be viewed in Adobe Reader or Acrobat, and within the following internet browsers; Internet Explorer, Mozilla Firefox, & Safari. Google Chrome does not display the speaker notes.
Known Nonferrous Metallic Mineral Deposits
There are at least seven nonferrous metallic mineral deposits that are known to have;
- significant economic interest in terms of substantial private capital investment
- have had the delineation completed to point that a significant deposit is identified
- have had economic feasibility or pre-feasibility studies started or completed.
PolyMet Mining: Locations of NorthMet Deposit & Potential Plant Site
Click to enlarge image
See a map (as of 2/2014) of the known metallic mineral deposits listed above
Those deposits and associated companies are as followed:
- PolyMet's NorthMet deposit (Duluth Complex)
- Twin Metals' Maturi, Birch Lake, and Spruce Road Deposits (Duluth Complex)
- Teck American's Mesaba Deposit (Duluth Complex)
- Cardero's Titac and LongNose titanium deposits (Duluth Complex)
Note, there is an eighth nonferrous metallic mineral deposit, known as the Tamarack deposit, located near the town of Tamarack in Aitkin County. Kennecott Exploration, working for Rio Tinto, began an exploration drilling program there in 2002. Since then Kennecott Exploration has been actively completing evaluation drilling of the deposit.
The time-frame from discovery to development is measured in decades for seven of the above deposits, with the exception being the Tamarack deposit (one decade thus far). Copper & nickel mineralization was first discovered in rocks in 1948. This sighting led to the discovery and delineation of most of the known Duluth Complex mineral deposits between the years 1950 and 1975. Recent technological advances in hydrometallurgical extraction (using sulfuric acid and a "pressure cooker" vessel) of metals and higher global metal prices have brought new capital investment expansions to known deposits and new economic evaluations.
PolyMet Mining has the most advanced project and is currently writing a Draft Supplemental Environmental Impact Statement (SEIS).
If you have additional questions please contact:
Dennis Martin, Mineral Potential Section Manager
MN DNR - Division of Lands and Minerals
500 Lafayette Road
St. Paul, Minnesota 55155-4045