Radioactive waste also plays a significant role. Uranium tailings are waste by-product materials left over from the rough processing of uranium-bearing ore. They are not significantly radioactive. Mill tailings are sometimes referred to as 11(e)2 wastes, from the section of the Atomic Energy Act of 1946 that defines them. Uranium mill tailings typically also contain chemically hazardous heavy metal such as lead and arsenic. Vast mounds of uranium mill tailings are left at many old mining sites, especially in Colorado, New Mexico, and Utah. Although mill tailings are not very radioactive, they have long half-lives. Mill tailings often contain radium, thorium and
Uranium trioxide which operates at the world's largest uranium refinery at Blind River, Ontario, produces high-purity uranium trioxide. It has been reported that the corrosion of uranium in a silica rich aqueous solution forms uranium dioxide, uranium trioxide, and coffinite. In pure water, schoepite (UO)O(OH)·12(HO) is formed in the first week and then after four months studtite (UO)O·4(HO) was produced. This alteration of uranium oxide also leads to the formation of metastudtite, Like all hexavalent uranium compounds, UO is hazardous by inhalation, ingestion, and through skin contact. It is a poisonous, slightly radioactive substance, which may cause shortness of breath, coughing, acute