Leaching behaviour of calcined magnesite with ammonium-chloride solutions

The leaching behaviour of calcined magnesite with ammonium chloride has been studied to ascertain the effect of different variables viz. temperature, concentration of ammonium chloride, Particle size, calcination temperature, hydration and the effect of calcium chloride addition on the rate of dissolution. The rate of dissolution is not affected by ammonium chloride concentration. The reaction rate mechanism has been discussed in terms of the shrin-king core model for spheres. The activation energy for the leaching of particles of —75+63 gm calcined magnesite was found to be about 43.2 + 0.5 kJ mol'. It is indicated that the reaction is chemically controlled and the rate is proportional to the inverse of initial size of magnesia particles.