Are You Ready?


June 1, 2009

Clearly, aggregate producers do indeed “got fines.” Here are more ways to market them.

A funny thing happened at a recent American Kennel Club agility trial. Rosie and I were at the first obstacle waiting for the signal to start. I was trying to psych her up with an excited “Are you ready!?!” I knew the answer was “YES!” But I failed to anticipate Rosie’s enthusiastic response. Next thing I knew, she was two obstacles down the course with me madly running behind yelling out commands for the next obstacles. Actually, it was fun.

The Carved in Stone column in the February 2009 issue of Aggregates Manager described a potential use for massive amounts of limestone fines in a yet-to-be-implemented process called Accelerated Weathering of Limestone (AWL). I began with the question ‘Got fines?’ I knew the answer was “YES!” But, as with Rosie, I failed to anticipate the enthusiastic response. I have received a flurry of requests from folks asking about markets for other kinds of fines, not just limestone fines for some potential futuristic market driven by Accelerated Weathering of Limestone. This column will briefly describe some of the lesser known, ‘green’ applications for fines.

An obvious agricultural application for limestone fines is for liming fields. But fines from some metamorphic or igneous rocks may have value for re-mineralizing soils by providing plants with essential nutrients such as iron, potassium, and magnesium. Applied research into the growth of crops using re-mineralized soils has given varied results. The outcomes of some trials give positive results, and the outcomes of others show no significant change in plant growth rates. Fines have also been used in the manufacture of artificial soils and in composting where they may lower ammonia production during composting and raise composting temperatures.

Cement production requires four major constituents: calcium carbonate, quartz, aluminum, and iron. The cement sector has been conducting research on the use of quarry fines that contain those constituents in cement manufacturing. By utilizing waste fines, cement can be considered a green product. Also, research at the University of Wisconsin has shown that limestone quarry fines and fly ash can be used to produce an effective, low-cost, self-compacting, green concrete, thus replacing the use of Portland cement in certain applications.

Fines might find application in other innovative, eco-friendly products such as green roofs, eco-friendly ‘slate’ roof tiles, and cob buildings.

Green roofs are specially constructed roofs covered with gardens or other plantings. Fines could be used in the soil mixtures, but they must meet specific shape and size distribution parameters for these applications

And speaking of roofs, eco-friendly roofing slate is produced from resin-bonded recycled plastic and dolomite/limestone fines, which serve as a filler material. Other fillers derived from fines might also be suitable for this product, although research is required to determine the suitability of the fines to this application while providing excellent insulation and heat storage properties.

Fines could also be used in earth construction applications such as cob houses. Cob structures are made with straw, dirt, and water mixed together to produce one massive structure, something like adobe, except adobe is made into forms that can be stacked like bricks. When cob dries, it resembles rock or concrete, and when coated with plaster, can withstand significant weathering.

Capturing these markets might not be easy, but…

Are you ready?

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