The Nucor Corp. iron plant in Convent is back in production and operating at 85 percent of capacity.

Nucor Steel Louisiana’s direct reduced iron had been shut down since November, when a process gas heater failed and had to be repaired. The plant restarted production toward the end of March, the company said in an earnings report this week

The Louisiana plant burns natural gas to make high-purity pellets from iron ore. Nucor mixes the pellets with scrap metal to make steel.

The Charlotte, North Carolina, company reported net earnings of $67.8 million, or 21 cents per share, for the first quarter, compared to net earnings of $111.0 million, or 35 cents per, for the first quarter of 2014. Nucor’s net sales decreased 14 percent to $4.4 billion in the first quarter from $5.11 billion a year ago.

Nucor said it expects earnings in the second quarter to be “somewhat improved” from the first quarter. Although margins in the steel mills segment are expected to improve, they will remain under pressure because selling prices have not fully stabilized and imports remain at high levels, the company said. The price pressure is expected to offset benefits of lower average raw materials costs in the second quarter.