Energy / Energy consumption is the designation for the product of performance (output) x time, and is specified in kWh. In melting, the concept of “energy consumption” per tonne of melted material is usually of interest. Here however, a distinction must be made between theory and practice. The theoretical requirement is around 390 kWh per tonne of iron. The grid energy demand of a well-designed high-output casting furnace is 510 to 540 kWh/tonne at the tapping temperatures usual in foundries (approx. 1,450 to 1,500 °C), while typical plants in practical melting operation require 585 to 640 kWh/tonne.[1] If a crucible furnace is operated as a “melting machine” with optimum charging, extraction and process control, energy consumptions of 560 kWh/tonne at the higher tapping temperature of 1,550 °C can be achieved. The surcharge compared to the high-output range is due to temperature: approx. 15 kWh/t per 50 K of additional temperature, on the grid side (calculation check: 0.83 kJ/(kg·K) x 50 K = 11.5 kWh/t of useful energy, roughly 15.3 kWh/t of grid energy at an efficiency of 0.75; cf. /melting-time/), so that 560 kWh/t at 1,550 °C is consistent with the high-output range at 1,450 to 1,500 °C.
References
- Dr. Erwin Dötsch (ABP Induction Systems GmbH): Induktionsofentechnologie und Energieeffizienz (induction furnace technology and energy efficiency). GIESSEREI 06/2011, published on guss.de (Bundesverband der Deutschen Gießerei-Industrie e. V.): specific enthalpy 390 kWh/t for melting and superheating cast iron to 1,500 °C, grid energy demand 520 kWh/t at 1,500 °C, practical melting operation 560 to 650 kWh/t. Accessed 27 August 2026.