With $2.6 million from the Minnesota legislature in 2016, NRRI is moving forward with its Mining Innovation Initiative. The funds were provided to support large-scale process demonstrations and test innovative technologies that address challenges facing the Minnesota Mining Industry. Five projects have been identified to fulfill this initiative with completion, or significant progress, targeted for mid-2018:
New iron ore flotation recovery process
Separating the iron ore from the rock is traditionally done with low intensity magnets. It works great for the magnetite ore – it’s magnetic, after all. But magnetite ores are expected to be tapped out of Minnesota’s Iron Range in the next 10 – 15 years. What then?
NRRI is developing a new process we’re calling “NatFlot,” a natural pH flotation process that recovers two other valuable iron oxide minerals – hematite and goethite. Bench scale testing shows that the NatFlot process is more effective, with potentially lower cost and less environmental impact.
“We had higher recovery, we can make a higher grade concentrate with half of the reagent costs and in a natural pH solution,” explained NRRI Researcher Tom Petersen. “It’s just a better process.”
The middle and east end of Minnesota’s Biwabik Iron Formation is currently being mined for magnetite, but toward the west end there’s some 5 – 7 billion tons of goethite and hematite containing ores, plus more resources with all three oxide ores. NRRI is testing the reaction of the different Minnesota ore resources to the NatFlot process at the bench scale and then will run pilot tests of 10 tons or more.
Microbial Iron Liberation for Sulfate Removal
Using bacteria to remove sulfate in water systems has the potential to be very cost effective and versatile. First, the sulfate is converted to sulfide with naturally-occurring bacteria, and then it must be transformed into a solid (elemental sulfur or metal sulfide) for removal.
But there’s a hurdle to jump. Neutral pH mine or industrial water cannot carry a high metal concentration, making sulfide capture methods inefficient.
Using geochemistry, microbiology and geology, NRRI plans to jump that multidisciplinary hurdle.
The first step of using bacteria to convert the sulfate to sulfide is well understood. The next step requires the sulfide to bind to specific metals so that it can precipitate in the water column for removal. Reactive iron is often added to water to precipitate sulfide as solid iron sulfide. Although Minnesota has access to a wide range of iron-bearing minerals, especially waste materials in the form of tailings and mine dust, they haven’t been thoroughly tested for this purpose.
NRRI Researcher Chanlan Chun is working with colleagues Nate Johnson (UMD) and R. Lee Penn (UM-TC) on this project. They are testing a variety of mining waste materials including magnetite-rich ore, iron carbonate-rich waste rock, hematite-rich waste rock, taconite tailings and more for their reaction with sulfide. Then, they’ll enhance the process using bacteria and low electrical voltage to produce iron ions for sulfide precipitation.
“We hope to use the natural process in a controlled way,” explained Chun. “Basically, we free the iron so that it can react with the sulfide using readily available taconite tailings.”
It’s basic research with a specific goal – to improve the natural, biological sulfate removal process. Once perfected at the lab bench scale, Chun will scale up the experiments to larger water columns. The lab research is expected to be completed in two years.
Innovative Filter Technology Demo
The goal of limiting sulfate to 10 parts per million in Minnesota water bodies was set in 1973. NRRI isn’t here to debate that standard – we are here to seek new tools and solutions.
New technologies are being developed to address sulfate, mercury and other pollutants that are a problem from Albert Lea to Ely. One particular filtration technology is showing promise elsewhere in the world and NRRI wants to scale it up to a pilot-scale demonstration.
Collaborating with industry partner Process Research Ortech, Inc., NRRI scientists will experiment with a unique filtration technology to see if it can be adapted to Minnesota water issues. If other remediation methods can reduce pollutants from thousands of parts per million, the hope is that this technology can take water from levels of 100 parts per million to 10 and meet the standard. NRRI will be testing a variety of media in the filter system.
Iron Reduction Simulator to produce high value iron
NRRI is preparing for the Iron Range’s future by designing and building an iron reduction simulator. This test size unit will provide a research tool for the iron ore and steel industry to transition from taconite pellets to direct-reduced grade pellets, direct reduced iron and other higher value iron products.
“Blast furnaces have served the industry well but the taconite industry in northern Minnesota must adapt to the electric arc furnace market which demands higher purity iron,” said NRRI Coleraine Site Manager Kevin Kangas.
The simulator will provide a new, large-scale test capability that more closely simulates the dynamic operating conditions found in today’s commercial higher value iron processes. With this additional capability, NRRI will be the only research facility in the world with a full range of iron ore and iron product research capabilities, from iron ore crushing all the way to production of direct reduced iron and pig iron.
There are a few taconite pellet producers in northern Minnesota moving toward producing direct reduced iron. The simulator, currently in the conceptual design and market research stage, will facilitate the growth of the high value metallics market.
Interactive, online Natural Resources Atlas
Vast amounts of data on Minnesota’s natural resources are collected and archived by a variety of organizations. That’s a good thing. But the information isn’t necessarily easy to access or easy to understand. That’s a problem NRRI is collaborating on with creation of an online Natural Resource Atlas for Northeast Minnesota.
It is being designed so both citizens and resource management agencies can access information on minerals, forests, water quality, land use, infrastructure and much more. This web-based tool and database will translate data into user-friendly, comprehensive information that can inform a range of land management issues.
“The Atlas levels the playing field for people who have to make important decisions about our state’s natural resources,” explained George Host, NRRI Initiative Director. “Not just for agencies, but industry, environmental groups and the general public as well.”
Currently, NRRI is collaborating with state agencies such as the Department of Natural Resources, Minnesota Pollution Control Agency, and the Board of Water and Soil Resources to gain insight on what should be included in the Atlas.
A decision support system will be built into the tool to help the managers from these agencies gather relevant information with the flexibility to test different assumptions on specific areas of land. NRRI hopes to have the first phase of the project completed by the end of summer 2018, with plans to expand the Atlas statewide.