Study On The Aggregation And Growth Mechanism Of Nickel-iron Particles During Reduction Roasting Of Laterite Nickel Or

With the increase of stainless steel industry consumables and the rise of new energy industry,the consumption of metal nickel is also continuing to increase,at present,China’s native nickel consumption is the world’s first,but the domestic nickel ore resources are in short supply,nickel production is seriously insufficient,mainly relying on imports.Nickel ore resources are divided into nickel sulfide ore and nickel oxide ore（ie,laterite nickel ore）,of which nickel sulfide ore with high nickel grade accounts for about 30%of global nickel resources,and nickel ore with low nickel grade accounts for about 70%,but the accelerated consumption of nickel resources makes the reserves of nickel sulfide ore lower and lower,and the development of nickel oxide ore with rich reserves is becoming more and more important.The aim of this study was to obtain high-grade,large-sized ferronickel particles from low-grade laterite nickel ore by reduction-roasting magnetic separation process.For low-grade silicon-magnesium laterite nickel ore in a certain place in China,laterite nickel ore and roasting products were mainly analyzed by chemical multi-element element analysis,scanning electron microscope observation,X-ray diffraction spectroscopy and Fourier transform infrared spectroscopy analysis,and the particle size distribution of ferronickel particles in roasted ore was statistically calculated by Image proplus image software.The analysis of additive low-grade ferronickel concentrate showed that the total content of nickel and iron in the concentrate reached 43.31%（4.25%+38.06%）,and the main impurity was forsterite,and it contained trace amounts of tremolite.Through the additive variable study,when the low-grade ferronickel concentrate is 30%,CaF₂ is 9%,anthracite is 8%,the roasting temperature is 1250℃,the holding time is 60min,and the magnetic separation strength is 150m T,nickel grade is 7.76%and iron grade is 67.27%,the recovery rate of nickel is 98.90%,and the recovery rate of iron is 85.17%.Statistics on the particle size of ferronickel particles in the SEM topography map:the addition of low-grade ferronickel concentrate and CaF₂can increase the average ferronickel particle size of the product,and when only low-grade ferronickel concentrate was added,laterite nickel ore only appeared sintering,while low-grade ferronickel concentrate and CaF₂ were added,and solid solutions appeared in roasted ore.With the increase of CaF₂ consumption,the silicate structure in the raw ore changed,and a small amount of tremolite was generated,resulting in a decrease in the melting point of the slag of the system,which was conducive to the accumulation and growth of ferronickel particles.When the addtion of additives was determined,the variable studies of roasting temperature and holding time showed that the particle size of nickel,iron grade and ferronickel alloy in the product increased slowly with the extension of holding time,and the particle size increased more significantly with the increase of temperature.On this basis,the growth kinetics model of ferronickel particles in the reduction roasting process of laterite nickel ore was established:Sellars simplified model,Sellars-Anelli type model and Hillert model,and error analysis was carried out,and the Hillert model had the highest accuracy in predicting the growth of ferronickel particles.The hillert model is:d²-d₀²=6769.24×t×exp[-123990.6/（RT）],which can effectively predict the growth process of ferronickel particles during the reduction process of laterite nickel ore.