Abstract: The invention refers to a methodology for the removal of inorganic components such as potassium, sodium, chlorine, sulfur, phosphorus and heavy metals from biomass of different origins, such as from agricultural, forest or urban origin and any mixture therefrom, from low quality coals such as peat, lignite or sub-bituminous and/or bituminous coals, from urban and/or industrial origin residues and wastes, which are possible to include as much organic—>5 wt %—as inorganic—<95 wt %—material and from sludges that are obtained from sewage treatment plants. The method includes the following steps: providing a salt, mixing water with the salt to produce an aqueous solution that contains salt, leaching the raw material with the aqueous solution that contains salt, preferably a salt containing zirconium or yttrium.