Process for producing sodium carbonate and sodium bicarbonate in a continuous mode out of trona comprising: c) feeding crushed trona, an extraction water and an additive in a first leaching tank containing a dissolution solution comprising sodium carbonate and sodium bicarbonate, wherein the additive is selected from the group consisting of: anionic hexametaphosphate, anionic polyphosphate, anionic polyphosphonate, soja lecithine, anionic polycarboxylate polymer, anionic polyacrylate polymer, anionic polyacrylate-polyacrylamide co-polymer, anionic hydrolyzed polymaleic polymers, anionic maleic-acrylic acids copolymers, anionic acrylic acid-phosphonic acid copolymers and combinations thereof; d) dissolving at least partially the crushed trona in the dissolution solution in order to produce a first suspension; e) removing continuously the first suspension from the first leaching tank and feeding it with an additive into a second leaching tank wherein the additive is selected from the same group of additives of step c); f) dissolving at least partially the remaining crushed trona from step d) in the second leaching tank in order to produce a second suspension; g) separating the second solid particles from the second solution to produce a production solution comprising sodium carbonate and to produce a production solid comprising the second solid particles comprising sodium bicarbonate.