Li recovery from slags
Publication Date: 2016-Apr-19
The IP.com Prior Art Database
Lithium recovery from slags
The recovery of lithium from pegmatic minerals such as spodumene has been extensively described.
The lithium-bearing minerals are firstly subjected to physical separation operations to produce a concentrate. The further steps are metallurgical, including high temperature calcination or roasting. This thermal treatment is performed at 800 to 1100 °C and is essential to convert the silica structures into a more reactive form. This conversion is usually described as an alfa to beta transformation. Additives such as lime may be added to bind the silica. The enhanced reactivity greatly facilitates the leaching of lithium, using acidic solutions or even water. The lithium can then be separated, e.g. as insoluble LiCO3.
The recovery of lithium from spent lithium-ion batteries has also been proposed. One option is to smelt the spent batteries or their scrap, together with a small amount of slag formers. The slag may contain alumina, lime, silica, or other relatively easily oxidized species. Most of the lithium also reports to the slag. Depending upon the batteries fed to the process, the lithium concentration in the slag can be higher than in natural ores, with values of 10% by weight or more of Li2O being practicable. Such metallurgical slags offer therefore a particularly attractive source of lithium.
It has moreover been found that such metallurgical slags can readily be leached for the recovery of lithium, without subjecting them to a separate therma...