Process for metal recovery from steel plant dust
US4610722A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 31, 1985 |
| Grant date | Sep 9, 1986 |
| Priority date | — |
| Expiry date | Jan 31, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S75/961
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A process is provided for hydrometallurgical processing of steel plant dusts containing cadmium, lead, zinc, and iron values, along with impurities such as chloride and fluoride salts of sodium, potassium, magnesium, etc. The first step in the process involves leaching the dust in a mixed sulfate-chloride medium that dissolves most of the zinc and cadmium. Any iron and aluminum dissolved in this step is precipitated by oxidation and neutralization. Zinc is recovered from the resulting solution by solvent extraction which provides a raffinate which is recycled to the leaching step with a bleed stream also provided for recovery of cadmium and removal of other impurities from the circuit. The lead sulfate residue from the leaching step is leached with caustic soda, and zinc dust is used to cement the lead out from the caustic solution, which then joins the main solution for zinc recovery. The residue from the lead leaching step is mixed with iron-aluminum oxide precipitate and agglomerated into pellets using cement. These pellets can be charged into steel furnaces for iron recovery or stored as a nontoxic waste.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.