Here are some videos from YouTube.They will help you to have...

Here are some videos from YouTube.
They will help you to have more idea about potahs mining.

Conceptual Potash Mine in Saskatchewan - Click here
(Athabasca Potash which was taken over by BHP last year)
Animated video - A potash mine and production plant. You can also see the shafts (headframes) here.

Building a Headframe (Shaft) at new PotashCorp Mine - Click here
You'll see how big is a headframe (shaft) and expensive to build it.

Potash mine reconnaissance - Click here
Driving a car in potash mine. They are driving in a sylvinite layer. Everywhere is potash. You'll see the hight of the mine is about 3 meters. The height of the most potash layers in Canada is around 3-4 meters. Same as ELM's potash layers which is even higer grade than in Canada.

A tour at Saskatchewan PotashCorp underground Allan Mine
- Click here
This is one of the biggest potash mine in the World. Huge!

Solution mining - Click here
And this is the solution mining technique from Western Potash Corp which is still alive as an explorer in Canada