Spodumene, conversion

At least the petalite conversion aspect of this data appears to be confirmed in some deposits, since after the entire pegmatite was solidified much of the petalite appeared to have been transformed into spodumene and quartz, and occasionally some eucryptite and quartz. The spodumene was in the form of psuedomorphs after petalite, and its very low iron content was similar to that of petalite, and much lower than that of most primary spodumene. However, this phase data and these reactions do not appear to have general applicability, since (1) solid phase reactions do not occur without the solid being remelted or dissolved, at least on a molecular scale, and then recrystallized after the reaction has taken place. (2) The data shows 3-spodumene being stable at 680°C, whereas at atmospheric pressure the change in form from a to 3-spodumene only occurs in ore concentrates above about 1000°C. Also, P-spodumene has never been found in a lithium deposit, and a-spodumene s melting point is shown as 700°C compared to its atmospheric value of 1423°C. (3) Changes in pressure normally have only a relatively minor effect upon a solid s... 

The recovery of lithium from spodumene ore was discontinued by Foote in 1984 (1986, USGS, 2000) and the mine and plant placed in a stand-by condition. It was officially closed in 1991 and the mine and plant dismantled in 1994 (USGS, 1997). However, the Kings Mountain conversion plant (converting lithium hydroxide to other lithium products) continued as a major processor of Clayton Valley and Salar de Atacama lithium carbonate into other lithium chemicals and lithium metal. Butyl lithium was produced at their New Johnsonville, Tennessee and Taiwan plants, and many other lithium chemicals were made at their parent company, Chemetall GmbH s plant at Langelsheim, Germany. 

Figure 1.87 Flowsheet for the acid-roast conversion of spodumene into lithium carbonate (Wilkomirsky, 1998).

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