Control of silica polymerisation during ferromanganese slag sulphuric acid digestion and water leaching

Manganese extraction of up to 90% is obtained and the leach residue presents good latent hydraulic properties, which can be used as an addition to Portland cement or a gypsum replacement. More than 95% of the initial silica content of the slag is rejected in the leach residue, and a residue silica content of more than 27% is obtained. Thus, silica solubilisation and polymerisation are controlled and solid-liquid separation is accelerated.