Helping Sparrows Point Increase Productivity in the BOF

Drop-in sensor equipment — designed and built by Research, is helping Sparrows Point boost productivity in the BOF. The device — a type of thermocouple delivery system — determines steel temperature in a BOF without a time-consuming vessel turndown. This enables the operators to quick-tap the heat — saving 6-8 minutes per heat — increasing productivity and providing time for vessel lining maintenance.

Reducing Costs of Tundish Linings at Sparrows Point

With the advancement of continuous casting technology, various improvements in tundish refractories have been made to improve quality and installation techniques and to lower unit cost.

A team of Sparrows Point Operations, Home Office Purchasing and Research was organized to select and implement a robotic spray system to apply tundish linings.

A careful selection and implementation of the robotic spray system has resulted in a 12% material savings and a 40% reduction in labor. A fully automatic, one-person operation capable of spraying a uniform lining thickness with trouble-free deskulling has been achieved.

Improving Flow of Steel in Tundish Shrouds at Sparrows Point

Research and Operations, in association with several refractory suppliers, initiated a project to investigate tundish shrouds with alumina clogging resistant materials.

To improve performance and better suit the Sparrows Point casting needs, Research suggested modifications to a supplier's existing product that helped improve the flow rate and reduce clogging. As a result, shroud life has been doubled — increasing productivity and reducing refractory cost.

Enhancing Breakout Prevention at Sparrows Point

Breakout prevention systems installed in the molds of the continuous caster at Sparrows Point had been plagued by false alarms of breakouts that caused a loss of productivity. An Operations/Research team made a systematic study of every alarm file — and constructed an off-line breakout detection model. The study revealed that defective thermocouples were a major cause of false alarms. A thermocouple evaluation program was written to generate a daily report on the performance of each thermocouple based on an examination of the previous day's performance.

The report made daily recommendations on which thermocouples should be disconnected. The study enabled Sparrows Point to reduce the incidence of false alarms by about 35% — and paved the way for additional enhancements to operating practices.

Mold Performance Improvements at the Burns Harbor No. 2 Slab Caster

A joint program between Burns Harbor and the Research Department was implemented to improve mold performance and eliminate network cracks on the No. 2 caster. The options to achieve the two objectives were to:

• fully coat the four working faces of the mold with a nickel sublayer and a thin chrome overlayer
• make the four copper plates thinner to offset the thermal resistance introduced by the nickel-chrome coating
• improve the maintenance practices utilized for the copper plates and
• improve width and taper control on the narrow walls.

As a result, mold service life has been quadrupled, network cracks on plate grade slabs have been totally eliminated, thermal stability of the mold has been improved and the potential for scrapping mold coppers for reasons of wear has been eliminated.

Reducing Corner Cracking on Burns Harbor Plate Grade Slabs

Corner cracking of plate grade slabs at Burns Harbor caused a substantial quality problem — affecting up to 60% of all plate grade slabs.Research and Burns Harbor developed an extensive casting machine monitoring program to identify and eliminate the cause of slab misshaping and attendant corner cracking. The study recommended machine and secondary cooling modifications that resulted in reduction of corner cracking incidence to about 5% of the slabs.

Helping Burns Harbor Achieve Higher Slab to Plate Yields

Working with the Burns Harbor plate team, Research developed a unique computer approach that optimizes the application and cutting of stock slabs into different plate sizes and orders.

This optimization process is critical to obtaining good slab-to-plate yields. In the past, decisions were made with the aid of a computer program that used rules-of-thumb to determine how to cut slabs. To improve the application and cutting of stock slabs, the Burns Harbor/ Research team developed a Plate Mill Global Providing System (GPS-1) for use on a computer work station, using an advanced mathematical model and 45 user-friendly screens that define operating environment. As a result, GPS-1 has been used to develop providing parameters for over 75% of the stock applications.

Reducing Plate Mill Yield Losses

A plate destined for a customer is obtained by trimming the sides and ends of typically non-rectangular “as rolled” plate produced on our plate mills. A “statistical providing” computer program has been developed to minimize these trimming losses. The program specifies optimal plate aim width and thickness and incoming slab weight based upon predicted plate rectangularity and statistical characterization of finished plate length, width, and thickness rolling capabilities of our mills.

Research, using laboratory physical modeling facilities, also has developed new rolling practice guidelines to improve rectangularity of plate produced in our mills. The guidelines determine thickness reductions to be taken during prebroadside (initial plate lengthening) and broadside (plate widening) rolling as a function of slab geometry.

Implementation of these technologies has contributed to a significant reduction in yield loss at both Sparrows Point and Burns Harbor.

Ongoing Research Page 2