Iron or “Ferrous” Mining
Iron mining is significantly different than non-ferrous or sulfide mining. Because of the magnetic properties of iron and lack of sulfide, in its simplest definition, iron is mined using water and magnets to pull out the iron. And because of the extraction and mining process differences, most states which mine the majority of our nation’s iron have different regulations for ferrous and non-ferrous mining operations.
Iron which has been casted has many specific uses including pipes, engines, and appliances, but most prevalent is its use in making steel. The many different steel types are comprised of almost entirely iron combined with small amounts of other metals to form various steel alloys. Steel is the most widely used and useful metal known to modern man and is used 20 times more than all other metals combined.
Steel’s relatively low production cost and strong properties make it the main structural metal in engineering and building products accounting for nearly 90 percent of all metal used each year. About 60 percent of iron and steel products are used in transportation and construction, 20 percent in machinery manufacturing, and most of the remainder in cans and containers, in the oil and gas industries, and in various appliances and other equipment. Iron and the resulting steel was a major driving force in our country’s industrial revolution.
Over the years, North American iron and steel prices have fluctuated due to influences from foreign markets, shipping costs, union developments and the reorganization of our nation’s steel companies. Today, the market is favorable for iron produced in the Upper Midwest due to advanced mining technologies and efficiencies; proximity of industry and manufacturing; available shipping avenues; and the quality of iron ore found in Midwest deposits.
In the Midwest, Michigan and Minnesota, unlike Wisconsin, have separate regulations to specifically address each mining industry or process to ensure better efficiencies, more appropriate use of resources and better suited environmental safeguards. Like our neighbors, Wisconsin has one of the best defined and high-quality iron ore deposits in the country, but without the appropriate regulations unique to each type of mining, Wisconsin is not poised to compete in the ferrous, or iron, mining industry.
The term non-ferrous is used to describe natural materials or minerals which do not contain iron. Non-ferrous mining usually refers to critical and strategic metals, which include copper and nickel; and precious metals, which include gold, silver and platinum.
Critical and strategic metals are types of base metals which provide the “base” for much of our life-supporting needs such as hunting and farming tools; building structures; cooking utensils; and electric power transmission and generation and have been used throughout history to develop civilizations because of their availability and abundance in the earth.
Precious metals such as gold and silver and strategic metals such as copper, zinc and nickel are mostly found in sulfide mineral deposits, which are deposits where sulfur ions bond with metallic ions — or sulfur attaches to the metal to form a mineral compound.
The mining of nonferrous or metal sulfide minerals is commonly referred to as sulfide or nonferrous mining. But it is not a type of mining process, only the mineral being mined. Sulfur is not used in the mining process, but is attached to the sought-after ore.
Mining of nonferrous minerals presents a different challenge than ferrous mining. Some sulfide minerals will oxidize and form sulfuric acid when exposed to oxygen in the air and then water from precipitation. The resulting acid can dissolve minerals and release metal into the water. The industry term for this process is Acid Rock Drainage (ARD).
ARD has been the main source of environmental concern in the sulfide mining process. During mining’s earlier years, the impact to the environment was not well understood and ARD was not adequately contained and eventually reached groundwater and streams. Today, mining standards, processes and technologies prevent and contain ARD so as not to harm the environment. Mining companies must be good stewards of the environment and our state’s regulations and laws for nonferrous mining ensure that this happens. Technologies and practices from the early days of mining are no longer tolerated or allowed, similar to other industries within our state that have evolved like automaking, meat packing, chemical manufacturing, farming and dairy producing.
A successful nonferrous mine, which is indicative of our state’s specific, nonferrous mining regulations and monitoring and a responsible mining operation is the Flambeau Mine in Ladysmith, Wisconsin.
During its mining operation all of the surface area drainage and water pumped into the pit went into a treatment plant that successfully purified the water so it could be safely returned to the environment. Upon closure, to avoid ARD, the pit was backfilled with the waste rock that was originally stripped from the pit along with 30,000 tons of limestone and ground water level was re-established to cover the remaining sulfide minerals, thus preventing oxidation and ARD.
Land at the site was reclaimed and Wisconsin continues to monitor the area for ARD, with none found to date The Flambeau Mine was closed more 10 years ago and did not have any violations of its permits in construction, operation, closure and reclamation.
Using the science of today’s mining industry, sulfide minerals can be successfully mined without the harmful environmental impacts of tomorrow.