Casting

A wide variety of processes that can be part of finishing are grouped under casting and shaping (rolling). Casting is a stage in finishing operations where the hot metal with the right properties is turned into intermediate, marketable products. Casting can be done as a batch (producing ingots) or continuous (producing slabs, blooms or billets) process. In most mills, casting is performed in continuous casting machines and the significantly low share of ingot casting is mainly used for speciality products.

Information on cast iron production is available here.

CastingSchematic

CastingTechnologies & Measures

Technology or MeasureEnergy Savings PotentialCO2 Emission Reduction Potential Based on LiteratureCostsDevelopment Status
Continuous Casting

Energy savings are reported to be 5.86 GJ/t-billets (UNIDO, 2011. p. 42)

Commercial
Efficient Ladle Preheating

In a US based facility installation of recuperative heaters reduced fuel consumption for ladle preheating by 28%.  This system saves approximately 14 TJ/y  of natural gas. 

Emissions reduction of 1.1 kg CO2/t-steel is estimated (US EPA, 2010).

Capital costs of ladle heaters are reported to be $70 000/unit (Worrell et al., 2010. p. 97).

Commercial
Efficient Tundish Heating

In a US based plant, installation of recuperative tundish heaters reduced fuel consumption for tundish heating by 26%.  Total annual energy savings of the equipment is reported to be 1.05 TJ (Worrell et al., 2010. p. 97). 

A recuperative tundish heater was intalled at a US based plant at a cost of $ 45 000 (Worrell et al., 2010. p. 97). 

Direct Rolling (Integrated Casting and Rolling)

The specific energy consumption should be 40% lower than that needed for a traditional rolling mill. Energy savings of 60% with regard to the traditional cycle are possible.

In an application in Japan equipment and construction costs were approximately ¥200 million and ¥50 million, respectively (NEDO, 2008).

Commercial
Endless Strip Production (ESP)

Specific energy consumption decreases by 40 – 60% as compared to a traditional rolling mill.

Environmental emissions will drastically decrease due to reduced energy consumption by avoiding reheat furnaces.

Processing costs are lower due to reduced consumption of energy and other consumables.

Commercial
Thin Slab Casting - Near Net Shape Casting

TSC is estimated to reduce energy consumption by 4.9 GJ/t-crude steel.
TSC with a tunnel furnace offers an energy savings 1.08 GJ/t-steel cast (US EPA, 2010. p. 24)

TCS is estimated to reduce CO2 emissions by 779 kg per ton of product. 

Investment costs for a large-scale plant were estimated to range from $234.9/t-product with a resultant cost savings of approximately $31/t-crude steel.
TSC is estimated to have a payback time of 3.3 years (US EPA, 2010. p. 24). 

Commercial
Strip Casting – Castrip® Process

Compared to thick slab casting (hot rolling, pickling and cold rolling), the Castrip® process saves approximately another  2 GJ/t.

Correleating from the energy savings reported in APP (APP, 2010. p.94), the process is estimated to redcue CO2 emissions by 80-90% comparing to conventional casting. 

Commercial
Strip Casting

The savings over traditional thick slab continuous casting include 0.32-0.55 GJ/t for electricity and 1.2-1.5 GJ/t for fuel (US EPA, 2010. p.25). 

Commercial
Integrated Casting and Rolling

Energy savings can range from 35% to close to 100%.  

CO2 emissions are reduced due to reduced fuel consumption. 

Commercial
Using Unheated Tundish

This technology will result in 78% reduction of natural gas consumption.

Fuel savings will lead to emissions reduction.

The life time of the tundish lids will increase by 90%.

Commercial
In-Situ Real-Time Measurement of Melt Constituents

it is estimated that worldwide application of this technology in steel plants can save 27.4 PJ of energy. 

Commercial cost ranges from $750000 to $2 million. A US-DOE project aims at producing the system costing less than $100,000.

Demonstration
Continuous Temperature Monitoring and Control

An improvement in energy efficiency of up to 5 % is expected by the application of this technology.

This technology reduces costs of rejections and re-works/re-melts.

Demonstration
MGGate for Continuous Caster

Each 10% Increase in sequence length offers the possibility of a 0.1% reduction in steel production energy use.  If this technology is adopted all across the US, annual energy savings can be 2.1 PJ. 

Initial capital cost ranges from $175,000 to $250,000 per strand.

Demonstration
On-line Laser-ultrasonic Measurement system

US flag Documented annual fuel savings for the first installed unit are on the order of 5 per- cent, with energy savings of 6.74 GWh.

US flag GHG emissions could be expected to drop by 0.3 million metric tons carbon equivalent per year.

US flag Cost savings are ap- proximately half a million dollars annually. 

Commercial
Elimination or minimization of oscillation marks

US flag Adoption of this technique may lead to energy savings in the order of 30 PJ year.

US flag Environmental savings are estimated to be 1.86 million ton of CO2 /year.

Demonstration