An additional technology that, on its own provides significant benefits for steelmakers, is the HYTEMP pneumatic transport system for sending hot DRI from the reduction reactor to the EAF shop. When combined with the ENERGIRON ZR Process, the benefits increase substantially by bringing hot, high carbide iron to directly feed the melting furnaces.
The HYTEMP System involves an ENERGIRON hot discharge direct reduction reactor connected to an adjacent electric furnace mill by means of a pneumatic transport system. HYTEMP iron is DRI produced at high temperature (700°C) and which is pneumatically transported from the reactor discharge to the meltshop for direct feeding to the EAF. In this manner, the energy value of the hot DRI is capitalized in the EAF.
This process scheme offers the most adequate arrangement for integrated steelmaking facilities due to the important benefits capitalized in the EAF. Hot DRI is sent to the meltshop, where it is temporarily stored in insulated inert storage bins for feeding to the furnace by continuous injection mechanisms which deposit the material directly in the metallic bath surface.
Currently the Ternium Monterrey 4M plant and both Emirates Steel DR plants produces hot-discharge DRI, using the HYTEMP System for hot DRI transport to the meltshop. Cold DRI is also produced via an external cooler if required.
The product is transported to the furnace by means of a carrier gas, via the interface bin where the carrier gas is separated from the hot DRI and where depressurization also takes place.
Hot DRI is discharged to the EAF surge bin, which feeds the electric arc furnace. The carrier gas is separated from the hot DRI in the pressurized interface bins, and it is passed through a quenching/scrubbing system for cooling and cleaning. Then, the carrier gas is recycled to the pneumatic transport circuit by means of the recycle compressor, thus closing the pneumatic transport loop.
According to the particular requirements of the steelmaking facilities, an off-line discharge for DRI cooling can be used during EAF downtime, or an external cooler can be incorporated for cold DRI production, or a briquetting machine can be installed in case that part of the production is being sent for export.
As the DR plant designed for HYTEMP iron production is linked to steelmaking facilities, the reactor tower, pneumatic transport system and EAF feeding bins can be arranged in the most adequate layout to minimize distances and to match the continuous DRI output with the batch consumption of the meltshop.
The HYTEMP system was not only the first successful continuous hot DRI charging system, having been in operation since 1998, but it is easily the most efficient and productive, with no fines losses from the system. HYTEMP is virtually maintenance-free with no recorded downtime in any of the plants using the system since it first started up over 15 years ago.