The multipurpose smelting unit MAGMA can be used for waste-free processing of high-ash (ash content up to 35%) thermal coals for generation of electric power.
Production capacity of MAGMA for incineration of high-ash thermal coal is 50-100 tons per hour.
Production of saleable electric power is up to 90 MWh.
Flow diagram of processing of high-ash thermal coal
Principally, two routes of processing of high-ash coal can be implemented.
Route 1
- Incineration of coal in the smelting chamber of the unit in air enriched with oxygen on the layer of the molten slag;
- Afterburning of the formed flue process gases in a heat-recovery power boiler installed over the smelting chamber of MAGMA;
- Production of electric power by traditional processing route used in thermal power industry.
When burning high-ash thermal coal in MAGMA, ash contained in it is smelted and dissolved in the slag bath.
Temperature of molten slag in the smelting chamber is 1500-1600°C. This allows to adjust the composition of the slag being smelted by adding fluxes.
Slag is used for production of cast-slag products or cast-slag crushed stones that by their quality are not inferior to natural granite crushed stones.
Principal physical and mechanical properties of cast-slag crushed stones
| Properties | Unit | Cast-slag crushed stones | Granite crushed stones |
| Density | kg/m3 | 2800-3000 | 2500 |
| Strength limit compression | MPa | 200-500 | 100-300 |
| Strength limit bending | MPa | 20-30 | 5 |
| Abrasivity | kg/m2 | 0.5-0.7 | 1-5 |
| Water absorption | % | 0.1-0.2 | 0.1-1 |
| Frost resistance | cycles | over 300 | 300 |
The dust captured by the gas treatment system is injected by injectors into the smelting chamber, to the molten slag where it is assimilated by slag.
Route 2
- Gasification (incomplete burning) of high-ash thermal coal in the smelting chamber of the unit on the layer of the molten slag. The produced gas is mainly composed of CO and H2 and some quantity of water vapour;
- Cooling of gas in a special heat exchanger. Cleaning of gases from dust and dewatering;
- Generation of electric power from dried gases in a gas turbine.
Chemical composition of molten slag is also adjusted by adding flux and it is used at a later stage for production of saleable cast-slag products.
The dust captured by the gas treatment system is injected into the molten slag. Thus environmentally clean and waste-free processing of high-ash thermal coal is achieved.
During incinerating high-ash coal we can achieve partial reduction of iron from oxides contained in the ash. Produced additional saleable product can be used in production of steel at a later stage.