Process for the selective precipitation of at least one conjugate base and/or at least one metal cation from an acidic preparation by neutralization, the process comprising the steps of: a) providing at least one calcium carbonate source having a weight median particle size d 50 from 0.1 to 500.0 μm in the form of a powder or an aqueous slurry, b) providing an aqueous solution having a pH value from 0.0 to 7.0, c) providing an acidic preparation comprising at least one conjugate base and/or at least one metal cation, d) contacting the aqueous solution of step b) with the at least one calcium carbonate source of step a) for obtaining an aqueous slurry in which at least a part of the at least one calcium carbonate source is dissolved in the water phase of the aqueous slurry as calcium hydrogen carbonate, e) contacting the acidic preparation of step c) with the aqueous slurry obtained in step d) for adjusting the pH of the resulting reaction mixture to a pH value being higher than the pH value of the acidic preparation of process step c) for precipitating the at least one conjugate base and/or the at least one metal cation from the acidic preparation as water insoluble salt/salts and optionally process step f) of stepwise increasing the pH value of the supernatant of the reaction mixture obtained in process step e), wherein contacting step d) is carried out in that the pH value of the aqueous solution provided in process step b) is adjusted to a targeted pH by i) the addition of the at least one calcium carbonate source provided in process step a), and/or ii) the addition of the supernatant of the reaction mixture obtained in process step e) and/or process step f) if present and wherein the process is a continuous process, wherein the supernatant of the reaction mixture obtained after separating the water insoluble salt/salts of the at least one conjugate base and/or the at least one metal cation from the reaction mixture is used as the aqueous solution of process step b). a) providing at least one calcium carbonate source having a weight median particle size d 50 from 0.1 to 500.0 μm in the form of a powder or an aqueous slurry, b) providing an aqueous solution having a pH value from 0.0 to 7.0, c) providing an acidic preparation comprising at least one conjugate base and/or at least one metal cation, d) contacting the aqueous solution of step b) with the at least one calcium carbonate source of step a) for obtaining an aqueous slurry in which at least a part of the at least one calcium carbonate source is dissolved in the water phase of the aqueous slurry as calcium hydrogen carbonate, e) contacting the acidic preparation of step c) with the aqueous slurry obtained in step d) for adjusting the pH of the resulting reaction mixture to a pH value being higher than the pH value of the acidic preparation of process step c) for precipitating the at least one conjugate base and/or the at least one metal cation from the acidic preparation as water insoluble salt/salts and optionally process step f) of stepwise increasing the pH value of the supernatant of the reaction mixture obtained in process step e), i) the addition of the at least one calcium carbonate source provided in process step a), and/or ii) the addition of the supernatant of the reaction mixture obtained in process step e) and/or process step f) if present and