Study On The Mechanism Of Microwave Strengthening Leaching Of Steelmaking Waste Slag By Ammonium Salts

The converter steel slag can be used as a perfect material to storage and fix CO2dueto that it contains lots of calcium minerals. With the process of indirect aqueous fixationCO2, using ammonium chloride solution as the leaching agent to leach the calcium of theconverter steel slag can realize the cyclic utilization of the leaching agent in the nextcarbonation stage, and the content of foreign ions in leachate is less which is beneficial toprepare the high-purity calcium carbonate products.In this study, the characteristics of the converter steel slag were investigated, and themorphology and phase composition were also analyzed before and after microwaveprocessing.The effects of different parameters on the temperature-rising behavior, the pHand the conductivity variation of leaching system were studied by the self-mademicrowave experiment device. The thermodynamics of Ca2+complex equilibrium inCa2+-NH3-NH4Cl-H2O system was calculated based on the exponential computationmethod and the double equilibrium method. To explore the influences of differentleaching parameters on the leaching rate of calcium ions and foreign ions, theexperiments of microwave strengthening leaching of converter steel slag by ammoniumsalts were conducted, and the dynamics mechanism of leaching process was also studiedto improve the leaching rate of calcium ions.The research results showed that the main phases of converter steel slag werecalcium minerals, and the calcium minerals can all react with ammonium chloridesolution between0and100degrees, except for calcium carbonate. After microwavetreatment, the internal cracks formed in converter steel slag particles. In the leachingprocessing, the apparent activation energy of leaching reaction was decreased bymicrowave strengthening, and the leaching rate of calcium ions can reach up to90%withlittle foreign ions existed in lechate. In addition, the increase of microwave power,solid-liquid ratio and initial concentration of leaching agent can improve the leachingrate of calcium ions. Whereas the increase of the initial leaching agent volume canreduce the leaching rate of calcium ions. The change of the initial concentration ofammonia in leaching agent and the stirring speed had non-significant influence on theleaching rate of calcium ions. Moreover, the diffusion was the reaction link ofnon-isothermal phase of leaching reaction.