Wet Extractive Grinding Process for Efficient Calcium Recovery from Steelmaking Slags

Abstract

This paper presents a process improvement of the pH-swing process (referred to as X2PCC) wherein a steelmaking slag is used as a source of calcium oxide for the mineral carbonation of CO2. We first dissolve Ca from the slag, then separate the solid phase by filtering, and, finally, bubble CO2 into the Ca-rich solution to precipitate it as CaCO3. The yield of calcium in the extraction step partly limits the process feasibility. Our objective is to apply a new extractive grinding method to enhance the extraction of Ca from steelmaking slags. We compared three cases: 1) mechanical mixing extraction with original grind slag A (0–250 μm); 2) mechanical mixing extraction with fine dry-grind slag B (0–50 μm); and 3) the new extractive wet grinding process with original slag A (0–250 μm). In this new extractive process, we combine the grinding and extraction steps in order to increase the rate and yield of the process. This method significantly reduces the energy requirement which makes this process feasible for industrial application.