Study On The Effect Of Fe₂O₃ On The Crystallization Behavior Of Secondary Nickel Slag Glass-ceramics

Nickel,as an important strategic resource,produces nickel slag containing valuable metals such as iron,chromium and nickel in the production process.As the iron in nickel slag exists in the form of Fe₂Si O₄which is difficult to reduce.Excessive pursuit of iron reduction will increase the production cost and lose the economy of iron extraction.How to economically extract iron and synergize the utilization of slag is an important issue of concern for the nickel industry.The composition of glass-ceramics is somewhat similar to that of nickel slag,while iron and its oxides in the slag can act as nucleating agents.Therefore,the preparation of glass-ceramics from secondary nickel slag after moderate iron extraction is a possible way for its efficient resource utilization.In this paper,it is proposed that the iron in nickel slag is moderately reduced to give full play to the economic value of iron extraction from nickel slag.Meanwhile,the remaining iron-containing tailings are used to prepare glass-ceramics to maximize the economic benefits of the two synergistic uses.Based on the nickel slag composition of one company,the secondary nickel slag with different reduction rates is calculated to obtain the content of residual iron oxides;the microstructure and properties of glass-ceramics with different Fe₂O₃content are studied by using it as the base composition and external blast furnace slag as raw material;the heat treatment system of glass-ceramics is optimized to study the kinetic behavior of crystallization of glass-ceramics.The conclusions of the study are as follows.（1）With the increase of Fe₂O₃content,the crystallization temperature of the base glass decreases and then increases,which plays a significant role in promoting the precipitation of the system.The structure of the glass-ceramics samples was relatively optimal when the reduction rate of nickel slag was 70%（Fe₂O₃content of 9.32 wt%）,and the crystalline phases precipitated in the glass specimens are all anorthite and ferrobustamite.（2）The optimal nucleation and crystallization conditions for the glass-ceramics with 70%reduction rate of nickel slag（Fe₂O₃content of 9.32 wt%）are:nucleation temperature 870℃,nucleation time 90 min,crystallization temperature 960℃,crystallization time 90 min.The order of the effect on the strength of the samples is:crystallization temperature>crystallization time>nucleation temperature>nucleation time.（3）With the increase of Fe₂O₃content,the activation energy of crystallization and thermal stability show a decreasing trend,and when the Fe₂O₃content is 9.32 wt%,the activation energy of crystallization and thermal stability of the samples are the lowest values,and the main crystalline phase content is the highest.When the heating rate is below 25℃/min,the crystallization mechanism of glass-ceramics is monolithic crystallization.With the increase of heating rate,some samples transition from monolithic crystallization to surface crystallization.