Road dust is a widespread problem in North Dakota and the US in rural areas where the majority of roads are unpaved. Mining and drilling operations also generate large amounts of dust due to heavy traffic. This dust creates an environmental hazard that impacts crops as well as the health of peoples living and working in these areas. Road dust generation also results in excess erosion of gravel roads and increased maintenance cost associated with their upkeep. The most common road dust suppressing agents in use today are magnesium chloride and calcium chloride. Although effective, they are corrosive to vehicles and infrastructure and do not perform well under extremely dry conditions. These negative aspects have driven the development of organic based road dust suppression agents such as polymer emulsions, tall oil, petroleum and lignin derivatives. This research will focus on the further development and field testing of soy based dust control agents.

Currently, the major feedstock for biodiesel production in the US is soybean oil. The conventional production of biodiesel involves a chemical reaction called transesterification where soy bean oil triglycerides are reacted with methanol by the addition of a base catalyst such as sodium hydroxide. This reaction produces approximately 90% biodiesel and 10% waste glycerol. This waste stream of crude glycerol exceeded 180 million gallons in 2013 and is expected to continue to rise with the growth of the biodiesel industry. With this growth, glycerol production is expected to outpace the current market demand for glycerol thereby driving the cost of crude glycerin down to less than $0.05 per lb. These factors make crude glycerol an attractive and inexpensive feedstock for the manufacture of soy based dust suppressants.

With current funding from the ND Soybean Council we are developing soy based dust control agents that utilize waste glycerol, soy biodiesel, soybean oil and other ingredients. This work is being conducted at the lab scale in order to investigate as many synthesis conditions and process variables as possible. The outcome of this current research will hopefully yield an optimal set of synthesis, formulation and application conditions that are ready for the next step of large scale production and gravel road testing.

The primary objective of the research outlined in this proposal is to transition from laboratory testing of dust control agents to full scale testing on gravel roads. The best soy based dust control agent currently under development with funding from the ND Soybean Council will be synthesized in much larger quantities followed by application to sections of gravel road and monitored for overall performance against magnesium chloride.

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Executive Summary

Project Title: Field Testing of Soy Based Dust Control Agents

Principal Investigator: James A. Bahr, North Dakota State University

Road dust is a common problem in the rural United States as well as in industrial and mining locations. This can lead to health issues for those living and working in these dusty environments. Windblown road dust also contributes to crop damage resulting in reduced yields adjacent to the gravel roadways. At the same time, the growing biodiesel industry is generating an excess of crude glycerol that is expensive to purify and/or dispose of.

In FY2016, with funding from the ND Soybean Council, we developed a soy based road dust control agent in our lab at NDSU. This was achieved by combining soy biodiesel with glycerol (from biodiesel waste) in a chemical reaction to synthesize a non-toxic, biodegradable and non-corrosive dust suppressant material that showed great promise in the lab.
With continued funding from the ND Soybean Council, we were able to scale up the synthesis in order to make enough material for a road test. For this effort, we synthesized 275 gallons of concentrated material followed by emulsification in water to produce a total of 1,200 gallons of soy based road dust control agent. This was enough to treat 600 ft. of road with a 30 ft. wide application. The remaining section will be treated with calcium chloride, which we will use as a comparison.

Magnesium and calcium chloride salts are the most commonly used dust suppressant materials because they are inexpensive and easy to apply (typically as water based brines). The problems with these salts is that they are corrosive to vehicles and tend to wash away in the rain resulting in environmental buildup.

One of the goals in developing a suitable alternative to these salts was to make the soy product a “drop-in” replacement so that existing equipment can be used to apply it. We achieved this goal and our material was applied to the test section using standard equipment without modification. Typical application rates were utilized and the road did not require pre-wetting with water.
Preliminary results from the field test are very promising with no measureable vehicle dust generated and little, if any washing out due to heavy rains. The surface of the treated road is compact and stable and we will continue to measure the dust control performance of this section over the following year.

The market in the US for dust control is quite large with over 1.3 million miles of unpaved roads and over $400 million spent annually to mitigate dust. A dust control product made from soy biodiesel/waste should create an expanded market and increased demand for soybean oil as well as for the waste glycerol generated from biodiesel production. In addition, soybean growers who live on gravel roads will benefit from an environmentally friendly dust control product that they can apply to their roads.