| Nickel is a silver-white metal and is corrosion-resistant.As an important strategic metal,it is widely used in the in the industries such as stainless steel,medicine,military and space.The world land-based nickel ore available are mainly nickel sulfide and nickel laterites.More than 60%of the world nickel production comes from nickel sulfide.With the depletion of nickel sulfide ores,the low-grade laterites have become the focus for nickel production.The process used to treat laterites are divided into 2 kinds:pyrometallurgy and hydrometallurgy process.The YN laterites used in this research contains high iron and alumina contents but low nickel,unable to be directly used for blast furnace.high-grade ferronickel can’t be obtained by traditional pyrometallurgy method and the laterites can’t be comprehensively utilized.In this article,reduction roasting-magnetic separation was introduced to treat the YN nickel laterites.A high-grade ferronickel,alumina and a magnetic tailing containing more the 50%iron are obtained.The main findings are as follows:1)First,the ore was analyzed by polarizing microscope,SEM,XRD and MLA.The results show that the main phases of the ores are goethite,chromite and hematite.Nickel mainly exists in goethite.2)The Gibbs free energy of the possible reaction has been calculated.The result shows that the process is feasible.3)The range of the optimum factor has been found by the orthogonal experiments.Then using the single-factor experiments,the exact factors have also been found.The results show that when laterite,sodium sulfate and coal have a mass ratio of 100:22:9,the laterite is roasted at 1200 ℃ for 80min,a ferronickel concentrate can be obtained with nickel grade 11.36%and recovery 83.35%respectively,which can be used for the making of stainless steel.4)Aluminum can be efficiently recovered by the addition of sodium carbonate.The result shows that when the ore,sodium sulfate,sodium carbonate and coal has a ratio of 100:14:8:8,and the sample was roasted at 1200℃ for 80min,a product ferronickel concentrate with 4.59%nickel can be attained and nickel recovery can reach 88.58%with an aluminum recovery of more than 60%.5)Kilo-scale experiments have been carried out for both processes.Nickel content of the ferronickel increases due to the change of experimental conditons.The ferronickel obtained was smelted in an electric furnace,making a further increase of nickel grade.Aluminum can also be recovered by adjusting pH of the leaching solution.A high-grade ferronickel,alumina and a magnetic tailing containing more the 50%iron can be obtained by the above process,making the laterites comprehensively utilized. |
