Method for removing arsenic from materials containing same

The invention relates to a method for removing arsenic from materials with a high arsenic and/or selenium content, comprising adding the material to a pressure reactor, adding an alkaline leaching solution, adding an oxidising gas, mixing the components in said reactor so as to produce a homogeneous pulp and subjecting said pulp to selective pressure leaching for the separation of arsenic. Said pulp is subjected to a first step of solid-liquid separation, producing an arsenic liquor and a solid with a low arsenic content. An Fe+3 and Ca+2 combination and Ce+3, Fe+3, Mg+2 precipitating agent is added to said liquor. The arsenic precipitation product is subjected to a second step of solid-liquid separation. Optionally, the method also comprises subjecting the arsenic-free alkaline liquor to a step of crystallisation of the sodium sulfate, and subjecting the product of said crystallisation (Na2S04) to a third step of solid-liquid separation.