Hertwich Ecomelt Melting Furnaces are generally based on integrated scrap preheating / delaquering and submerged melting process. They are designed for remelting of scrap with impurities like oil, paint, and plastic. Total non-metallic organic substances may reach 10% of charge weight, subject to calorific value.
Savings come not only from avoiding shredding and separating, but significantly from thermal reclamation of the hydrocarbons from paint and plastic. During preheating of such scrap, up to 80% of the gas consumption is substituted by the inherent energy of the gasified hydrocarbons.
The specific fuel gas consumption varies from 350 to 550 kWh/ton of aluminium during continuous operation subject to the quantity of organic impurities.
Hertwich Ecomelt furnaces for scrap type I - III are designed on the following principles:
- Automatic scrap charging
- Thermal gasification of organic content by heating the scrap in a hot-gas-flow to approx. 400 - 500°C. During this phase the aluminium does not start to melt, as the temperature of the hot-gas-flow is at all times below the melting temperature.
- Combustion and post combustion of gasified organics takes place in all chambers of the furnace. The gasified hydro-carbons contribute to the energy input for the melting process. The main chamber of the furnace is well suited for post combustion because of the constant high furnace chamber temperature (> 900°C) and the controlled furnace atmosphere.
- Melting of preheated scrap is exclusively by contact with liquid melt (submerged melting process). An electromagnetic liquid metal pump transports sufficient melt to the scrap. This method of melting results in the lowest achievable melt loss.
- Near continuous heating - charging and melting activities do not interrupt main burner operation.
- The majority of the melting energy is introduced to the melt in the main chamber in the form of radiant heat. The use of a regenerator ensures high combustion efficiency with low energy consumption.
Ecomelt PS (Preheat Shaft)
The Ecomelt PS melting furnace is well suited for efficient and economic melting of type III scrap including painted profiles with thermal break, baled litho sheets, UBC etc. In fact it is the most versatile melting device in terms of scrap grades and categories.
With the development of the preheat shaft furnace a melting capacity of 12 tons/hour (250 tons/day) is achieved. Specific energy consumption is as low as 350 - 550 kWh/ton subject to organic impurities.
The Ecomelt PS unlike Ecomelt PR furnace is not limited to a single batch, rather is the melting process continuous. The Ecomelt PS multi chamber furnace accepts several batch loads in the preheat compartment.
Scrap is loaded via a payloader into containers. The charging crane takes one full container at the time and charges the scrap load via a material lock at the top of the preheat shaft.
Most stringent environmental and emission regulations are met due to the combination of closed charging unit and high efficiently combustion equipment.
Ecomelt PR (Preheat Ramp)
The multi-chamber furnace with preheat ramp is best suited for loose scrap with moderate organic content. The scrap rate is up to 200 tons per day.
Scrap is charged with a charging machine onto the dry hearth ramp for preheating and gasification of organics. Thereafter the scrap heap is pushed into the melt bath by the charging machine or an integrated scrap pusher. The capacity of the charging machine is approximately 13 m³ with a maximum load of 5 tons.