The pretreatment process of limonitic laterite ores at low temperature and the mineral phase transformation mechanism were studied. The effects of temperature,duration,sulfuric acid and water addition on the activation pretreatment were investigated. The results showed that the extractions of Ni and Co increased with the increase of temperature,acid addition and duration,and adding a certain amount of water was beneficial to the extraction of Ni and Co. The optimal activation pretreatment conditions were as...