Browsing by Subject "Taconite aggregates"

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    A Brief History of the Use of Taconite Aggregate (Mesabi Hard RockTM) in Minnesota (1950s – 2007)
    (University of Minnesota Duluth, 2007-10) Oreskovich, Julie A
    Taconite aggregates (collectively termed Mesabi Hard Rock™) have been used as construction aggregate in Minnesota for nearly 50 years, dating back to the early days of the taconite industry. Coarse taconite tailings are a ready-made, free-draining, fine aggregate equivalent suitable for use as select granular and fine filter aggregates. Their angular interlocking form, when placed with water and covered with Class 5, produces sound embankment fill material. Their hardness, strength and durability produce superior wear and friction properties in bituminous mixes. This, coupled with 100% fractured faces, makes them ideal for Superpave mixes. Their cleanness (very low -200 mesh) makes them a valuable tool for adjusting volumetric properties in bituminous mix design. Crushed taconite rock brings the same hardness, strength and durability to the coarser aggregate size fractions, making it ideal for crushing to desired specifications for use as fill, filter material and the coarse aggregate component in bituminous and concrete mixes. Historically, taconite aggregate products have been used most when road construction, maintenance, and repair projects are in close proximity to the taconite operations, i.e., on the Mesabi Range. The 1970s and 1980s saw the use of coarse taconite tailings spread to the Twin Cities metropolitan area, as well as to the southern and western reaches of the state for use in bituminous overlays and surfacing. The 1990s and 2000s saw taconite aggregates become a staple of Duluth area bituminous contractors and road constructors, to the degree that they are used in some capacity in nearly every project. Millions of tons of taconite byproducts are produced every year in the mining and pellet production process. Couple this with nearly 50 years of production and the enormous size of this resource becomes obvious. While much of this material is consumed by the taconite mines for day to day operations (haul roads, tailings dams, shovel pads, drill hole stemming, etc.), much remains stockpiled and available for use. Infrastructure already in place for shipment of pellets (roads, railroads, and Lake Superior docks and ship-loading facilities) can be accessed for shipment of aggregates throughout the United States and beyond. This report is a historical narrative of the highlights of taconite aggregate usage as road construction aggregates in Minnesota. It documents how taconite byproducts have evolved from stockpiled "wastes" to become premium "in-demand" aggregates suitable for meeting today's infrastructure needs.
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    The Economics and Logistics of Transporting Taconite Mining and Processing Byproducts (Aggregate): Minnesota and Beyond
    (University of Minnesota Duluth, 2007-10) Zanko, Lawrence M
    Every year, Minnesota’s taconite mining industry generates over 125 million tons of mining byproducts, a figure that is more than double the entire state’s annual aggregate usage. Since 2000, the Natural Resources Research Institute (NRRI), University of Minnesota, Duluth, has been investigating how these vast quantities of taconite mining byproducts can be used for construction aggregate purposes on an expanded basis. However, if taconite-based aggregate is to be competitive beyond the Mesabi Iron Range, cost-effective rail transport options will be needed, and rail-related economic and logistical barriers must be identified, quantified, and overcome. The reality is, lower value/higher volume commodities like construction aggregates are often economically limited by their distance to market, due to the cost of transportation. Consequently, this study is focusing on rail transport by reviewing/identifying transportation networks, logistics, equipment availability, costs, and potential difficulties associated with moving taconite aggregate through that network. Truck, barge, and Great Lakes shipping are also being addressed. By identifying the key transportation and market-related issues, this study will give potential end-users inside and outside Minnesota a better understanding of how taconite aggregate could be an important alternative to “conventional” aggregate sources. Likewise, taconite producers will have a better understanding of the relative ease or difficulty of marketing and/or moving various types of aggregate, and the potential economic benefit(s) thereof. By improving our understanding of what the supply, demand, and movement dynamics are (and how they interrelate), the prospect for expanded use of taconite aggregate will be enhanced - a development which will ultimately be important for both the economy and the environment, a dual benefit measurable in both a dollars (economic) and tons (resource conservation) sense. This Technical Summary Report describes project activities and progress through October of 2007.