This study investigates the production of high-quality MgCl₂ from recycled waste magnesite powder with an average particle size of d₅₀ 0.079 mm using the HCl acid leaching method. The experimental parameters were, leaching temperature, leaching time, amount of the acid, liquid-to-solid ratio, scale-up factor, acid concentration, particle size and mixing speed. The experiments were performed under reproducible conditions. The results showed that optimum leaching parameters were: temperature of 70°C, 180 min leaching time, 130 cm³ acid consumption, 3.6 cm³/g liquid-to-solid ratio, scale-up factor of 1, 10.17 M acid concentration, 0.079 mm average particle size and a mixing speed 60 rpm. Under these optimum conditions, the leaching yield was 96.72%. The produced MgCl₂ solution contained 0.04% SiO₂, 0.36% CaO, 0% Fe₂O₃, 0% Al₂O₃, 46.73% MgCl₂, 52.87% L.O.I. and 99.60% MgCl₂+L.O.I. (= MgCl₂·6H₂O). These results indicated that high-quality magnesium chloride can be produced from waste magnesite powder.