Pretreatment method for utilization of coal ash landfilled in ash ponds

A method of obtaining a byproduct having increased purity of unburned carbon and amorphous compounds from coal pond ash, comprising:

• (a1) subjecting coal pond ash to screening and recovery;
• (a2) subjecting coal pond ash to screening, flotation, and recovery;
• (a3) subjecting coal pond ash to screening, float-sink, grinding, flotation, and recovery;
• (a4) subjecting coal pond ash to screening, float-sink, magnetic separation, and recovery;
• (a5) mixing a byproduct obtained through screening, float-sink, primary magnetic separation, and grinding of coal pond ash with a residue obtained in step (a2) and then performing secondary magnetic separation and recovery;
• or
• (a6) subjecting a residue obtained in step (a5) to magnetic separation and recovery.

A method of obtaining a byproduct having increased efficiency of recovery of Fe oxide from coal pond ash, comprising:

• (b1) subjecting coal pond ash to screening and recovery;
• (b2) subjecting coal pond ash to screening, flotation, and recovery;
• (b3) subjecting coal pond ash to screening, float-sink, and recovery;
• (b4) mixing a byproduct obtained through screening, float-sink, and grinding of coal pond ash with a residue obtained in step (b2) and then performing magnetic separation and recovery;
• or
• (b5) subjecting a residue obtained in step (b4) to magnetic separation and recovery.

A method of obtaining unburned carbon and Fe oxide from coal pond ash, comprising:

• (d1) subjecting coal pond ash to grinding, flotation, and recovery;
• (d2) subjecting coal pond ash to grinding, flotation, magnetic sorting, and recovery;
• or
• (d3) subjecting coal pond ash to grinding, flotation, primary magnetic separation, secondary magnetic separation, and recovery.

A method of obtaining a byproduct having increased strength from coal pond ash, comprising:

• (e1) subjecting coal pond ash to screening and recovery;
• (e2) subjecting coal pond ash to screening, flotation, and recovery;
• or
• (e3) subjecting coal pond ash to screening, float-sink, and recovery.