Study On The Kinetics Of Carbon Reduction In Chlorinated Roasting Of Laterite Nickel Ore

Global nickel resources exploration mainly involves two kinds of ore,sulphide ore and nickel laterite ore,the exploration of nickel sulfide ore mining resources leads to the sharp decline in reservation,the abundant laterite has attracted people's interest,more and more research efforts have been done to improve the utilization of nickel laterite ore.In this paper,Yunnan silicon magnesium low grade nickel laterite ore was used as raw material in order to research the reduction kinetics of the silicon magnesium laterite,and the content of sodium chloride was changed to investigate the effect on the reduction enrichment laterite,the results provide the theoretical support for the effective use of Chinese low grade nickel laterite ore.The kinetics of carbothermal reduction process of low grade laterite nickel add sodium chloride by thermogravimetric analysis was investigated,the degree of reduction and reduction rate were calculated from the measurement of weight loss.Kinetic parameters were calculated by Kissinger and Friedman methods,the trend of activation energy of carbon thermal reduction process can be fully demonstrated,by analyzing the thermogravimetric curve,the reaction process can be divided into three stages.The first stage is 500-750°C,the second stage is 750-1100°C,and the third stage is after 1100°C.The activation energy of the first stage can be calculated by the Kissinger method as508.8kJmol^-1,and the activation energy calculated by the Friedman method is417.1-532.1 kJmol^-1.In the second stage,the activation energy can be calculated by two methods as 226.5 kJmol^-1 and 242.2-384.5 kJmol^-1.The results show that the reaction activation energy can vary with the temperature,indicating that the chlorination reduction reaction of laterite is not a simple elementary reaction,but is composed of several parallel reactions and interaction reactions.Kinetic parameters were calculated by Flynn-Wall-Ozawa,Kissinger and?atava-?esták methods,the trend of activation energy of carbon thermal reduction process can be fully demonstrated,by analyzing the thermogravimetric curve,it was found that the carbon reduction process was influenced by the heating rate and the content of sodium chloride.The activation energy obtained by adding 4%sodium chloride and 6%sodium chloride by Flynn-Wall-Ozawa method was 205.47-426.46kJmol^-1 and 205.27-387.41kJmol^-1 respectively,the activation energy of 6%sodium chloride sample was lower,the same result can be obtained by using the Kissinger method.The most probable mechanism functions were obtained by chemical reaction control at low temperature stage,the reaction model is F2,in the high temperature stage,the reaction model is D1.