The company said the proceeds of the placing – which was oversubscribed – will help fund the drilling of up to eight extra bore holes.
Last year the company said test drilling at two holes between Whitby and Scarborough had revealed some of the best potash deposits in the world.
Potash is a pink-coloured potassium compound used in fertilisers. Canada is the world’s biggest producer.
Michael Rawlinson of Liberum Capital, who advised on the placing, said: “There has been a lot of interest from high profile investors and we are pleased with the outcome.”