Serpentinites used for carbon dioxide sequestration : a possible economic source for PGE
- Katherine A.
The platinum-group elements (PGE: Ru, Rh, Pd, Os, Ir, Pt) are among the most valuable metals in the world. Their myriad uses in electronics, jewelry, catalysis, and the automotive industry have increased PGE demand several fold in the last few decades, but the past few years have seen PGE supply largely unable to keep up with the increasing demand. Although the PGE are found in many types of rock bodies, in most cases they are present in such low concentrations that it is not economically feasible to extract them. The few economically mineable deposits generally fall into two categories: layered ultramafic intrusive deposits, such as the Bushveld Complex in South Africa, which contain PGE-bearing ore veins; and copper/nickel-bearing veins, such as the Norilsk-Talnakh District in Russia, in which the PGE are extracted as a byproduct of Cu/Ni mining. Only one economic PGE deposit exists in the United States (the Stillwater Complex in Montana), and it is small compared to the Russian and South African deposits (which supply most of the world's PGE needs). The recent interest in the use of serpentinites and ultramafic rocks as possible reservoirs for carbon dioxide sequestration has opened the door to another possible economic source for the PGE. Theoretically, the magnesium silicates in the ultramafic rocks and serpentinites can be reacted with carbon dioxide (either from the air or as a waste stream from a fossil fuel plant) to produce thermodynamically and geologically stable magnesium carbonates, which can be easily disposed of. The deposits being investigated for this process are located throughout the world; there are several in the U.S. alone. The PGE concentrations in these deposits are fairly low, and by themselves the deposits are not economically feasible sources for the PGE. However, part of the proposed carbonation process requires the crushing and magnetic separation of the rocks; the non-magnetic fraction is used for carbonation, while the magnetic fraction is treated to extract iron and other metals. Since most PGE-bearing minerals in serpentinites and ultramafic rocks are magnetic or are associated with magnetic minerals, the magnetic separation of the powder could serve to essentially concentrate the PGE from the rock bodies. Once the PGE-bearing minerals have been separated and concentrated, the PGE may be at economically extractable levels. The primary focus of this research is the investigation of the PGE concentrations in the serpentinites and ultramafic rocks that may be utilized in the carbonation process. The magnetic fraction from a representative serpentinite body will be analyzed for PGE to determine whether or not these rocks may be economic sources of the PGE.
- Research Organization:
- Los Alamos National Laboratory
- Sponsoring Organization:
- DOE
- OSTI ID:
- 975677
- Report Number(s):
- LA-UR-01-4382
- Country of Publication:
- United States
- Language:
- English
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