Abstract: Disclosed is a process for any productions that involve reacting or mixing two or more substances to form one or more new substances under low supersaturation. However, the specific process used to exemplify the present invention is the “wet process” phosphoric acid production, in which this process is achieved through dissolving the phosphate ore and dispersing the sulfuric acid separately and simultaneously with the gypsum slurry that has roughly stoichiometrically balanced calcium and sulfate ions in the solution and is also at considerably low supersaturation. The slurry carried out digesting the phosphate ore and the slurry accomplished dispersing the sulfuric acid then mix together to form the said gypsum slurry that has roughly stoichiometrically balanced calcium and sulfate ions in the solution and is also at considerably low supersaturation.