Two 210-ton EAFs, two twin-station LMFs and a twin vacuum tank degasser are all being built by SMS Group, Germany.

By Corinna Petry

teel Dynamics Inc. is well along its timeline for executing a plan, announced in early 2019, to open a 3 million-tons-per-year minimill in Sinton, Texas, a town with roughly 5,600 residents who enjoy a warm climate with average annual rainfall of 34 inches.

The location’s advantages are obvious. It’s 30 minutes from the Port of Corpus Christi, which serves other nearby steel-related interests in addition to oil and chemical companies. It’s 150 miles from Nuevo Laredo and 170 miles from Matamoros. Apart from SDI’s Omnisource scrapyards, the steelmaker will source scrap from a new acquisition, Zimmer Recycling, just outside Monterrey.

“It’s a big project and we’re completing it in the middle of a pandemic,” comments Glenn Pushis, senior vice president for special projects at SDI. The company broke ground last year and expects to start up production in 2021. “Building a steel mill in 18 months is super aggressive,” he acknowledges.

Liquid steel

The melt shop will consist of two electric-arc furnaces, each with 210 tons of capacity, two twin-station ladle metallurgy furnaces, and a twin vacuum tank degasser, all from SMS Group, Germany. The melt shop’s cycle time is expected to range from 30 to 45 minutes. The annual melting capacity is 3 million tons.

“The shop is laid out to feed a slab caster. Single slabs will be up to 5.5 inches thick and up to 84 inches wide,” Pushis says, adding that casting speed can reach 6 meters per minute.

Rolling & coating

Next is the Compact Strip Production (CPS) finishing mill, also from SMS Group. It will have six stands that will produce a final strip thickness of between 0.047 to 1 inch thick and create coils weighing up to 52.6 tons. Common widths will range from 38 inches to a “true 84 inches wide,” notes Pushis.

A continuous pickle line will accept coils from 38 to 78 inches wide and from 0.047 inch to 0.25 inch thick. The line can pickle coils at up to 820 feet per minute. Its annual capacity is rated at 1.1 million tons. SDI Sinton is installing a continuous tandem cold mill—five stand/six high; its annual capacity is 850,000 tons. Cold rolling speed will reach up to 3,969 feet per minute, according to the specifications.

“The hot rolling mill is a conventional style,” says Pushis. “It has a two-stand roughing mill with edging capability. That feeds into a six-stand finishing mill, then into two down coilers. The layout of the hot mill is designed for thermal mechanical rolling so we are able to produce advanced high-strength automotive steels and API grades.

“We go through the hot mill, then the pickle line and tandem cold mill. That facility can run straight through, or we can run the hot side and cold mill independently.” SDI can store hot band coil or take material off the pickle line and later reinsert that steel into the cold mill.

Building a steel mill in 18 months is super aggressive. This is the widest strip mill in North America.

The next operation, says Pushis, is galvanizing and Galvalume, a line that can produce up to 550,000 tons per year. The continuous line accepts strip from 36 to 76 inches wide in gauges from 0.01 to 0.16 inch. The speed for coating coil can reach 650 feet per minute.

From there, SDI is installing annealing capacity. Using 100 percent hydrogen, the Ebner furnaces manage coils of cold-rolled strip. “We have 12 furnace bases and we have room to expand to 24 bases,” says Pushis. Sinton’s annual annealing capacity is 250,000 tons.

“From there we have a single-stand, high-powered temper mill for fully processed cold-rolled products. The temper mill can go to 84 inches wide,” he says, and can temper 440,000 tons per year.

Finally, Danieli & C. Officine Meccaniche S.p.A. will install a 250,000-ton continuous paint line that can double coat or coat both sides of the strip. The line will accept coils from 36 to 72 inches wide, up to 32 tons. The paint line will coat pickled hot strip, cold-rolled, galvanized and Galvalume up to 0.076 inch thick.

Engineering

“One major design factor is that this is the widest strip mill in North America. Many companies roll only 78 or 80 inches wide,” Pushis says. Sinton will roll sheet up to 84 inches wide.

“The keys to this facility are the thermal mechanical rolling, the layout of the hot mill and the cold mill, heat treating as you are rolling, and quick quenching.” It even comes down to spacing out the cooling beds. “This is all highly engineered and important.”

Efficiency is a constant goal. “You can have a coil in two weeks. If you are talking about a standard product, that can come off the line quickly,” Pushis says. Custom gauges or custom colors will mean longer lead times.

Sinton will have 12 Ebner furnace bases with room to expand to 24 bases. Annual annealing capacity is 250,000 tons.

Advantages

The location is close to a deepwater port [Corpus Christi] to bring in iron units. “Pig iron can be melted in the EAF, and that comes from all over the world. We can bring in 50,000-ton vessels,” says Pushis. “Voestalpine has a DRI facility only 20 miles away. They will feed us 300,000 tons a year.”

Omnisource is working now to arrange consistent scrap sourcing for the Sinton mill. “And we just purchased Zimmer. That’s 500,000 tons coming through Laredo for this facility. So we have the [raw material] sources.

“We have a good supply of power. We have access to water—we are sitting on a water main that feeds the entire city of Corpus Christi,” Pushis says. “We have three Class I railroads—Union Pacific, Burlington Northern Santa Fe and Kansas City Southern. We have good road and highway infrastructure.”

SDI can affordably access Laredo and Brownsville, leading to the manufacturing center of Monterrey. Trucks and trains can “get quickly to the West Coast and our freight rate will be much better than from Gary.”

Partnerships

Steel Dynamics is in the process of signing long-term agreements with steel processors. “J&M Steel is moving on site, and we are working on other such partnerships,” says Pushis. “That allows us to ship large coils directly to them on campus and helps eliminate yield loss. These processors can take wide heavy coil and maximize their own productivity.”

Most of the toll processing will be slitting, leveling and cut to length.