Lithium Mining

[memoguy]

Hi! I am currently working on a research assignment about lithium. I am trying to find out how it is extracted from the earth. Here is what i know so far:

 

In chilli, the largest producer of lithium in the world, lithium is extracted from brine (water which contains lithium salt) of the Salar De Atacma, the largest salt flat in chilli. The brine is pumped into large solar evaporation ponds. Over a 18-24 month period the brine is evaporated until there is a sufficient concentration of lithium salts. This lithium salt is then transported via truck or pipeline to processing plants where it is converted to usable salt products such as Lithium Carbonate.

 

What i don't understand is how you get metallic lithium. I hope someone can point me toward the right direction.

[mississippichem]

They take the LiCl, melt it down and electrolyze it. This reduces the Li⁺ ion to Li metal, a one electron reduction.

[memoguy]

Ok, thanks. I have another question. Lithium reacts violently with water. But it is extracted in salt form from water. Why dosn't the salt react with water?

Edited August 17, 2011 by memoguy

[mississippichem]

Ok, thanks. I have another question. Lithium reacts violently with water. But it is extracted in salt form from water. Why dosn't the salt react with water?

 

The Li⁺ ion in the LiCl salt doesn't react with water. You're talking about the reaction:

 

[ce] 2Li_{s} + 2H_{2}O \rightarrow 2 LiOH_{aq} + H_2 [/ce]

 

LiOH is really just a solution of Li⁺ and OH^- so the salt reacting with water would basically be the reverse of the one above. The one above is very exergonic (thermodynamically favored), so the reverse is extremely endergonic (thermodynamically disfavored) i.e. not going to happen spontaneously if at all.

Edited August 17, 2011 by mississippichem