Study On The Adsorption Properties Of La³⁺/Ce³⁺for Blast Furnace Slag With Modification

Blast furnace slag is the main waste slag produced in blast furnace iron-making process.With the vigorous development of iron and steel industry in China,the discharge of blast furnace slag is increasing day by day.The accumulation of blast furnace slag not only increases the environmental burden,but also is a waste of resources.How to use blast furnace slag green and improve the added value of blast furnace slag have become a hot topic at home and abroad.China's rare earth reserves are abundant,but the number has been sharply reduced due to large-scale mining in recent years.At the same time,due to the immature mining technology,the rare earth elements infiltrated into the river and groundwater under the action of rainwater,causing the concentration of rare earth elements in the river water of the mining area to be too high.It is not only a great waste of rare earth resources,but also the pollution of water environment,threatening life and health.Therefore,the effective enrichment and recovery of rare earth ions not only has high environmental and economic value,but also an important protection for the country's strategic resources.In view of this situation,in order to achieve the purpose of waste treatment and environmental protection,this paper proposes the use of blast furnace slag for effective enrichment and recovery of rare earth ions.The characterization and analysis of blast furnace slag,crystallized blast furnace slag and acidified blast furnace slag were carried out by SEM,XRD and BET,and the adsorption of La³⁺/Ce³⁺was studied.In order to further study the adsorption behavior and mechanism of blast furnace slag,kinetics and isothermal adsorption model were used to fit.The details are as follows:?1?The adsorption experiment of La³⁺with blast furnace slag was carried out.The blast furnace slag particles are distinct and non-uniform in size and are amorphous glass bodies.In the experiment of adsorption behavior,the experimental data meet the quasi-first order kinetics and Langmuir isothermal adsorption model,respectively.The intra-particle diffusion model can well describe the adsorption process of La³⁺by blast furnace slag.Thermodynamic calculation shows that the adsorption of La³⁺by blast furnace slag is a spontaneous endothermic process.According to the response surface fitting data,it is clear that pH plays a dominant role in the adsorption effect.?2?Blast furnace slag was crystallized and used to adsorb La³⁺/Ce³⁺mixed solution.The microstructure of crystallized blast furnace slag becomes denser than that of blast furnace slag.When the crystallization temperature is higher than 700?,the crystal with main phase Ca2Al2SiO7 appears,and the specific surface area does not change obviously.The adsorption capacity is lower than that of blast furnace slag,and the cause of this situation is analyzed.In the experiment of adsorption behavior,the adsorption process of La³⁺/Ce³⁺by crystallized blast furnace slag can be well described by quasi-second-order kinetics and Langmuir isothermal adsorption model.?3?The blast furnace slag was acidified with different concentrations of hydrochloric acid and used to adsorb Ce³⁺alone and La³⁺/Ce³⁺mixed solution.When the concentration of hydrochloric acid is more than 0.3 mol/L,the acidified blast furnace slag becomes loose,the particle size becomes smaller and uniform,and has a certain degree of aggregation,and the crystals of SiO2 and Al2O3 mainly appear.Compared with blast furnace slag and crystallized blast furnace slag,the specific surface area of acidified blast furnace slag is up to 181.27 m²/g?0.5 mol/L?compared with that of blast furnace slag and crystallized blast furnace slag in the range of 4-6 m²/g.The experimental results show that the quasi-second-order kinetics,Langmuir isothermal adsorption model and intra-particle diffusion model can well describe the adsorption equilibrium data of Ce³⁺and La³⁺/Ce³⁺mixed solution of acidified blast furnace slag in one-component and two-component systems.The adsorption capacity of La³⁺/Ce³⁺decreased obviously in the two-component system,and the possible reasons were analyzed.