Magnesium carbonate was prepared by carbonization leaching from desiliconization slag of laterite nickel ore

and the content of NiO in the residue reached 2.96%.The results showed that extraction ratio of MgO increased with increasing stirring speed

reaction time and liquid-to-solid ratio

however

the extraction ratio increased firstly and then decreased with increasing reaction temperature.When stirring speed was 600 r·min-1

reaction temperature was 15℃

reaction time was 36 h and liquid-to-solid ratio was 40∶1

the extraction ratio of MgO could reach as high as 91.57%.XRD analysis indicated that the product was magnesium carbonate

and its physical and chemical properties conformed to the state standards of chemical industry.