Study On The Extraction Process Of Valuable Metals From Limonite-type Laterite Nickel Ore

With the increasing depletion of high-grade,easy-to-mine nickel sulphide ores and the low grade and large reserves of limonite-type nickel laterite ores,in which nickel is mainly in a homogeneous form with iron and is endowed in needle iron ore,how to use this type of nickel laterite ore in a reasonable and efficient way has become a hot issue that needs to be solved in the nickel metallurgy industry today.This thesis mainly introduces the characteristics and development status of nickel resources at home and abroad,and provides an overview of various current processes.Using a limonite-type laterite nickel ore from Indonesia as raw material,the reduction roasting-magnetic separation process,the chlorination separation-magnetic separation process and the atmospheric pressure acid leaching process are mainly used to study this type of laterite nickel ore,and the relevant research results are summarised.1.The reduction roasting-magnetic separation process of laterite nickel ore and its optimum conditions were analysed in terms of concentrate and tailings composition and their XRD patterns.The results showed that under the process conditions of 200 mesh ore as raw material,anthracite as reducing agent,the dosage of 10%of the ore,Ca O as flux,the dosage of 5%of the ore,roasting temperature of 1300?and roasting time of90 min,the grades and yields of valuable metals Ni and Fe were 1.25%,41.82%and72.36%,54.1%respectively;by X-ray powder diffraction,scanning electron microscopy and energy spectrum analysis,it can be seen that some of the iron oxides in the ore were reduced to metallic iron or enriched in the concentrate in the form of magnetic iron,which made the enrichment of nickel show less obvious and finally led to the fact that neither iron nor nickel was effectively enriched,which was the main reason for the low grade of nickel.2.The nickel laterite ore chloride separation-magnetic separation process and its optimum conditions were analysed for concentrate and tailings composition and their XRD maps.The results show that:using 200 mesh ore as raw material,using Ca Cl₂·2H₂O as chlorinating agent,the dosage is 14%of the ore,using anthracite as reducing agent,the dosage is 10%of the ore,the separation temperature is 1000?,the separation time is 120 min for the chlorination separation-magnetic separation experiment,under this condition,the grade and yield of nickel and cobalt can be obtained as 1.425%,0.235%and 80.2%,83.26%;from X-ray powder diffraction,scanning electron microscopy and energy spectrum analysis,it can be seen that although the nickel grade was increased in the experiment,it did not increase significantly due to the weakly magnetic magnesia olivine entering the concentrate with the metal monolithic alloy.3.The results of the study on the leaching of valuable metals from limonite-type nickel laterite ores using atmospheric hydrochloric acid showed that at a hydrochloric acid concentration of 10 mol/L,a raw material particle size of 200 mesh,a leaching temperature of 80°C,a solid-liquid ratio of 1:4 and a leaching time of 120 min,the leaching rates of nickel,cobalt,manganese,iron and magnesium were 34.3%,90.67%,64.23%,76.46%and 48.12%.The lower leaching rate of nickel was due to the similar leaching characteristics of nickel and iron during the acid leaching process,resulting in lower leaching rates for both.From the leaching kinetics study of Ni,Co and Mn,it can be seen that the leaching process in this experiment does not conform to the widely used contraction kernel model,while the fit with Avrami's equation has a good linearity,and the apparent activation energies of Ni,Co and Mn during leaching can be found to be 7.96,4.00 and 4.98 k J/mol respectively according to the Arrhenius equation.All three leaching activation energy values were in the range of 4-12 k J/mol and the effect of leaching temperature on the reaction rate constant was not significant.In summary,it can be judged that the leaching processes of Ni,Co and Mn are controlled by diffusion conditions.In this thesis,three different nickel laterite ore treatment processes were investigated.The reduction roasting-magnetic separation process was used to recover nickel and iron,which is a simple and feasible method that does not require the consumption of solvents,but is more energy intensive;the chloride ionisation-magnetic separation process was used to recover nickel and cobalt at lower temperatures,with less energy consumption and higher nickel and cobalt yields than the reduction roasting-magnetic separation process;the leaching of nickel laterite ores using atmospheric hydrochloric acid showed that acid leaching has a lower extraction rate of nickel from this type of laterite nickel ore.The results of the above study can provide a theoretical reference for the efficient development and utilization of limonite-type nickel laterite ores.