University of Missouri-Rolla researchers are developing ways to mine metals more efficiently, and the United States government has taken notice.
The U.S. Department of Energy recently awarded $79,064 to the UMR School of Materials, Energy and Earth Resources to help fund phase one of a project that utilizes high-pressure waterjets to separate minerals from rock.
The common practice of separating minerals from rock involves the extraction of large quantities of heavy material from an underground mine. The rock is then transported to a plant, where it is crushed, ground, and further processed until it yields a metal concentrate.
All of the left-over material taken from the ground has to be deposited in waste piles that take up space on the surface.
Dr. Larry Grayson, chair of the department of mining and nuclear engineering at UMR, says employing waterjet technology to extract minerals would be much more efficient.
We re proposing to leave the non-valuable material underground, Grayson says.
High-pressure waterjet technology has been proven to be efficient when it comes to cutting rock with precision. Dr. David Summers, Curators Professor of mining engineering and head of the UMR High Pressure Waterjet Laboratory, says the process is really just a naturally occurring event that is accelerated to an extreme.
Water erodes rock on a grain-by-grain basis, Summers explains. By using water at pressure, this erosion can be accelerated to take place in fractions of a second, and still remove individual grains of mineral. This greatly reduces the volume of material that has to be moved out of the mine and subsequently treated.
According to Grayson, the use of waterjets to liberate mineral grains from rock specimens underground would represent a huge reduction in the amount of energy currently required to mine and process the ore that contains the metals.
Dr. Lee Saperstein, professor of mining engineering at UMR, says mining is a costly endeavor.
First, miners drill and blast through rock, Saperstein says. Then they use a lot of energy to crush and grind the rock into powder, which is put into tumbling mills that circulate like washing machines.
The miners are finally left with the mineral grains, though some of the desired material is lost in the process.
You re always trying to increase the recovery rate without sacrificing the grade of the mineral, Saperstein says.
In Missouri, lead is the metal most sought after. In fact, more lead is mined in Missouri than in any other state.
UMR s primary operating partner in the new waterjet project is the Doe Run Co., which mines lead extensively in southeast Missouri. While the Department of Energy is providing the bulk of the funding for the waterjet project, Gardner Denver, an equipment company, and Doe Run are also supporting the research.
Doe Run is a high volume, low unit profit operation, Saperstein says. They re always looking for ways to be more efficient. If you can figure out a way to get a 90 percent recovery rate on minerals versus an 85 percent return, you re a hero.
Phase one of the project will last a year and will take place primarily on campus, according to Grayson, who says UMR will apply for more Department of Energy funding as soon as researchers can adequately test and validate their process of liberating mineral grains with waterjet technology.
Grayson adds that UMR s experimental mine could be used for testing as the project gains momentum in future phases.