Glassification of lead and silica solid waste
US4988376A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 2, 1989 |
| Grant date | Jan 29, 1991 |
| Priority date | — |
| Expiry date | Aug 2, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03C1/002
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
Lead or other heavy metals are rendered immobile for sanitary disposal by vitrifying the silica-based soil or other medium in which the lead or heavy metal is contained. The silica sand or other soil contaminated with lead is heated to the melting point of the silica. A melt accelerator or fluxing agent is added to lower the melting point of the silica. A reducing agent is added to cause a separation of the metallic phases from the glass. The glass formed retains a portion of the lead, with excess metals, e.g., gold, silver, and platinum, separating. These metals may be recovered at any time after this point in the process. In the case of a silica-poor medium, such as a soil that does not contain sufficient quartz to perform the process successfully, additional quartz sand or scrap glass is added to the process in quantity sufficient to ensure the formation of the glass slag. The slag formed by the process of the present invention is extremely impervious to leaching by groundwater, therefore removing the contaiminate from the environment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.