Process for preparing whitened fly ash

A method of making_ceramics, paint, rubber, and/or plastics, wherein the method comprises the steps of:

• (a) subjecting fly ash to a size classification step to obtain size classified fly ash having a particle size such that at least 90 wt % has a particle size of from 44 μm to 250 μm;
• (b) contacting the size classified fly ash from step (a) with water so as to form a slurry, wherein the slurry has a solid content of less than 40 wt %;
• (c) subjecting the slurry obtained in step (b) to an exhaustive magnetic separation step to form magnetically treated fly ash, wherein the exhaustive magnetic separation step comprises a first magnetic extraction step and a second magnetic extraction step, wherein the second magnetic extraction step is carried out at a higher magnetic field strength than the first magnetic extraction step. and each magnetic extraction step has a duration of at least 1 minute;
• (d) subjecting the magnetically treated fly ash obtained in step (c) to a wet milling step to form whitened fly ash, wherein the wet milling step is carried out in the presence of an acid;
• and
• (e) incorporating the whitened fly ash obtained in step (d) into a ceramic, paint, rubber, and/or plastic.