Microwave-Supported Leaching of Electric Arc Furnace (EAF) Slag by Ammonium Salts

Abstract

Abstract:The effect of microwave-supported leaching of electric arc furnace (EAF) slag by ammonium salts was investigated to improve calcium leaching ratio for CO 2 mineral sequestration process. The results show that the calcium leaching ratio from EAF slag at the constant temperature in the microwave field increases about 10% than that under the water bath at the same leaching time. The greater the microwave power, the higher the impact of calcium leaching rate, which proves that microwave treatment can improve the leaching ratio of calcium. The rapid calcium leaching step (up to 5 min) is possibly due to the easy reaction of calcium silicate, while the slower calcium leaching step (after 5 min) is owing to the difficult reaction of calcium ferroaluminates for the hydrolysis of iron and aluminum. The leaching behaviors of magnesium and calcium ions affected by different leaching parameters are similar and the concentration of aluminum, iron and phosphorus can be neglected. Calcium ion is probably not precipitated in the real leaching solution from steel slag by ammonium chloride solution as its concentration is less than 0.32 mol/L. However, the concentration of magnesium ion starts to drop sharply when the pH value is higher than 10 and it has precipitated completely at pH value of 11.6.

Evaluation of Microwave Intensified Vanadium Bearing-High Carbonaceous Shale Acid Extraction Process

“…As in situ heat generation alleviates the heat transfer limitations of the conventional ovens, materials can be processed at a faster rate via the use of the microwave ovens. The properties of in-core volumetric and uniform heating, lower thermal inertia and faster responses make microwave chemistry applied widely [7,8]. In the materials and metallurgy research, microwave assisted synthesis of catalysts, electrodes, and optical devices [9][10][11] have proven to be efficient with some special effects.…”

Calcium and sodium recovery from microwave‐pretreated red mud with added solid ammonium chloride

“…The Ca and Na recovery was evaluated to use potentially the leached solution for aqueous mineral carbonation to sequester CO 2 . Many studies have used an NH 4 Cl solution as a solvent during microwave‐assisted metal leaching processes . However, in this study, solid NH 4 Cl instead of an NH 4 Cl solution was used as a chlorinating agent during the microwave pretreatment of red mud to induce a rapid temperature increase by minimizing heat loss by water.…”

“…Many studies have used an NH 4 Cl solution as a solvent during microwave-assisted metal leaching processes. 23,28,29 However, in this study, solid NH 4 Cl instead of an NH 4 Cl solution was used as a chlorinating agent during the microwave pretreatment of red mud to induce a rapid temperature increase by minimizing heat loss by water. The NH 4 Cl as a chlorinating agent was selected because an NH 4 Cl solution was reported as an effective solvent for aqueous mineral carbonation when the solute is a material with high alkalinity (e.g.…”

“…After roasting the raw material at a high temperature, the chloride ions form metal chlorides, resulting in a high metal leaching ability. Recently, Tong et al . have reported that the microwave‐assisted leaching method using an NH 4 Cl solution as a leaching agent could enhance Ca leaching from an electric arc furnace slag for aqueous mineral carbonation.…”

The Indirect Mineral Carbonation of Electric Arc Furnace Slag Under Microwave Irradiation

“…Finely ground and heat-activated serpentine derived from mining residues has also been studied for CO 2 capture and sequestration 25 . Additionally, some unconventional methods, such as ultrasonic and microwave treatment, have been shown to be effective for leaching 26–28 . Our previous study showed that microwave irradiation can improve the calcium leaching ratio by approximately 10% 28 ; however, the leaching mechanism requires further research.…”