Plant for producing decarbonized oxide or hydroxide, comprising an electric calciner, a contactor, a pH correction apparatus and a dosing device, wherein: - the electric calciner is adapted to receive at the inlet a flow of carbonate, electric power and to release at the outlet at least one flow of carbonic gas at high temperature and at least one flow of oxide; - the flow of oxide is adapted to provide a flow of buffering substance; - the contactor is adapted to receive at the inlet the flow of carbonic gas released by the electric calciner, a flow of carbonate, a flow of water; - the contactor is adapted to make the carbonate react with water and the CO 2 present in the carbonic gas according to the following reactions CO 2 aq + H 2 O l ⇌ H 2 CO 3 aq ⇌ H aq + + HCO 3 aq − and CaCO 3 + CO 2 + H 2 O → Ca(HCO 3) 2(aq) (where Ca can be substituted with Mg if present in the carbonate) and to release at the outlet at least one flow of ionic mixture; - the contactor is provided with means for releasing non-soluble gases; - the pH correction apparatus is adapted to receive at the inlet at least one flow of buffering substance (440; 640) and the flow of ionic mixture, is adapted to make the ionic mixture react with the buffering substance (440; 640) according to the following reactions CaO + H 2 O + 2CO 2 → Ca(HCO 3) 2(aq) or Ca 2(aq) +2CO 2 → Ca(HCO 3) 2(aq) and to release at the outlet a flow of buffered ionic mixture; - the dosing device is adapted to receive at the inlet a flow of buffering substance (130; 630) deriving from the electric calciner and to release at the outlet a predetermined quantity of buffering substance (440; 640) to feed the pH correction apparatus and possibly a quantity of buffering substance (450; 650) available for use. - the electric calciner is adapted to receive at the inlet a flow of carbonate, electric power and to release at the outlet at least one flow of carbonic gas at high temperature and at least one flow of oxide; - the flow of oxide is adapted to provide a flow of buffering substance; - the contactor is adapted to receive at the inlet the flow of carbonic gas released by the electric calciner, a flow of carbonate, a flow of water; - the contactor is adapted to make the carbonate react with water and the CO 2 present in the carbonic gas according to the following reactions CO 2 aq + H 2 O l ⇌ H 2 CO 3 aq ⇌ H aq + + HCO 3 aq − and CaCO 3 + CO 2 + H 2 O → Ca(HCO 3) 2(aq) (where Ca can be substituted with Mg if present in the carbonate) and to release at the outlet at least one flow of ionic mixture; - the contactor is provided with means for releasing non-soluble gases; - the pH correction apparatus is adapted to receive at the inlet at least one flow of buffering substance (440; 640) and the flow of ionic mixture, is adapted to make the ionic mixture react with the buffering substance (440; 640) according to the following reactions CaO + H 2 O + 2CO 2 → Ca(HCO 3) 2(aq) or Ca 2(aq) +2CO 2 → Ca(HCO 3) 2(aq) and to release at the outlet a flow of buffered ionic mixture; - the dosing device is adapted to receive at the inlet a flow of buffering substance (130; 630) deriving from the electric calciner and to release at the outlet a predetermined quantity of buffering substance (440; 640) to feed the pH correction apparatus and possibly a quantity of buffering substance (450; 650) available for use.