Method for extracting nickel, cobalt and iron from limonite

The invention discloses a method for recycling nickel, cobalt and iron from limonite, and belongs to the field of metallurgy. The technology comprises the following steps: obtaining high-silica magnesium ore and low-silica magnesium high iron ore through washing and grading of limonite; adding both high-silica magnesium ore pulp and sufficient concentrated sulfuric acid to a double-screw material pushing reactor so as to dissolve most of soluble nonferrous metal and soluble iron; then performing solid-liquid separation to obtain atmospheric pressure leaching slag and atmospheric pressure leaching liquid; adding the atmospheric pressure leaching liquid and low-silica magnesium high iron ore pulp to a pressure pipeline reactor in proportion for pressure leaching; performing solid-liquid separation to obtain pressure leaching slag and pressure leaching liquid; then purifying the pressure leaching filter liquor to obtain a fine iron powder product. The technology has the advantages of high nickel and cobalt leaching efficiency, low sulfuric acid consumption, short reaction time and high production efficiency; moreover, pressure leaching is implemented by medium and low pressure equipment, so that the defects that high-pressure autoclave equipment is expensive and easy to scale are avoided; the main component iron in the ore can be economically and effectively recycled and effectively utilized, and the amount of waste residue is small.