Aside from high capital costs for the project, a major hurdle was that melt shop operations team members had to significantly modify their approach to steelmaking. All automated set-points for the steel charging system had to be reconfigured. Previously, around 100 tons of scrap steel were dropped, or “charged”, into the open electric arc furnace (EAF) from above, creating a surge of cold scrap steel, reducing furnace temperature, and requiring make-up of a large amount of lost heat. With the new scrap preheating process, the EAF roof is kept in place and a series of conveyors slowly feeds scrap metal into the EAF furnace. The 2,400 degree Fahrenheit off-gas exhaust is now drawn over the steel scrap while on the conveyor, preheating the scrap to between 600-800 degrees Fahrenheit and reducing furnace electrical and coal/gas energy demands. The hot scrap steel is then dropped into a large bath of molten steel that is heated by the electrode. This is different from the prior process, which slowly lowered the electrode onto a pile of cold steel.

Since this was a retrofit system, the operations team had many issues getting back to normal production volumes and quality. Issues identified by the team included:

• About 25% of the heat was diverted to other products due to variation in specifications
• The process was not capable of consistently removing enough chromium from the steel at the EAF
• The EAF needed to operate at less than full power to preserve anode life
• Off-gas temperatures were high, resulting in excess water usage to cool the off-gas
• All crews were running the EAF differently
• Burners were still oversized
• Connecting Car tips (connection of conveyor to furnace) were failing prematurely
• Scrap tracking was not accurate, resulting in inconsistent charge weights
• The draw on the EAF was not properly tuned for each step of the profile
• Top feed coal was not an efficient source of energy
• Bucket charge weights were not standardized 

To address these issues, Charter Steel formed a smaller employee team focused on understanding and optimizing the new scrap reheat process. This team worked closely with the Charter Steel’s internal energy department to use energy management tools that measure and monitor relevant variables impacting energy performance. A new EAF energy dashboard was created to provide relevant data for operators and engineers to monitor. Using this dashboard, the team working on the scrap preheat stabilization was able to shift their focus toward energy reduction. They utilized a consultant to conduct an EAF energy balance. New data sets were provided on key EAF energy metrics. The calculations revealed that adding excess carbon showed no improvement in energy being transferred to the steel. The team concluded most top-feed coal was being burned up in the top layer of slag and the heat from the reaction was exiting through the off-gas system. The consultant recommended using less coal and the next step was to figure out the best solution to reduce usage.

Armed with this data, the C-crew Furnace Operator and the Furnace Area Manager focused on reducing carbon usage. They combined their years of experience and expertise to begin the process of EAF profile modifications to reduce carbon usage. They trialed dozens of new profiles and quickly identified how the EAF was performing in each step and phase of a new profile. They stayed in constant communication on the performance of each new trial and discussed where they could continue to reduce coal from the process. Once a trial proved to be successful, a new profile was published and updated for the other crews. During the project, they were aided by the new energy dashboard to be able to view the performance of a new profile within 24 hours. They also used the dashboard to see the entire energy picture and quickly understand the impact of each change on total energy consumption.