ARGONNE, Ill. -- A simplified approach to removing metals and radionuclides from waste or process streams, developed at Argonne National Laboratory, could result in significant financial and environmental savings for a variety of industrial separations processes.
Financial savings come from reducing chemical purchases and capital expenditures, and environmental savings are brought about by allowing repeated re-use of process solutions, thus minimizing waste.
This new approach, which Argonne has patented, uses small magnetic particles with a chemical coating, a solvent containing an extractant that selectively attracts specific metals, said Argonne chemist and process developer Luis Nuñez.
These particles (from Cortex Biochem, Inc., San Leandro, Calif.) are poured into a tank containing a process or waste solution, where the coating extracts the low concentration of metal. The magnetic particles, and their metal baggage, are removed from the solution with magnets, Nuñez said.
The metal can be stripped from the particles, allowing both the metal and the particles to be recovered, while the process solution can be recycled to the plant. The extractants placed on the magnetic particles can be tailored to the need, for example, to remove radionuclides.
Compared to ion exchange processes, efficiencies with magnetic separation are as much as 100 times greater. The extractant coatings are effective in acidic and caustic conditions, eliminating problems and costs associated with neutralization. Unlike ion exchange and solvent extraction, this process is effective with fine particles.
This is an in-tank or near-tank process that is inherently simple, compact, low cost, and low maintenance. It could be applied in recovery, recycling, and waste minimization activities at many industrial sites. It would reduce the need for capital expenditure to address ever-increasing environmental compliance levels, greatly reduce the chemical inventory required for metals separation, and, in some applications, recover metals of potential commercial value. Among the industries in which this process could be applied are the electroplating, environmental, and mining/metallurgy industries.
The process has been demonstrated at bench scale for a wide variety of waste streams, and scaleup and pilot testing are planned. In other applications of magnetic separation, scaleup has been successful.
With more than 200 research projects and an annual operating budget of approximately $500 million, Argonne National Laboratory is one of the largest federal research facilities in the country. Argonne is operated by the University of Chicago as a part of the U.S. Department of Energy's National Laboratory System.