---
title: "Basic oxygen furnace (BOF)"
description: "A basic oxygen furnace (BOF) — historically the LD converter after the Linz-Donawitz process — refines molten pig iron from the blast furnace into steel by blowing high-purity oxygen onto the bath through a water-cooled lance. Each \"heat\" takes 30–45 minutes and produces 250–300 tonnes of steel."
canonical_url: "https://sylio.co/glossary/basic-oxygen-furnace"
last_updated: "2026-06-28T02:29:39.978Z"
---

A **basic oxygen furnace (BOF)** — historically the *LD converter* after the Linz-Donawitz process — refines molten pig iron from the blast furnace into steel by blowing high-purity oxygen onto the bath through a water-cooled lance. Each "heat" takes 30–45 minutes and produces 250–300 tonnes of steel.

## Off-gas

BOF off-gas is intermittent, very high-temperature (>1,600 °C at the converter mouth) and dust-laden. Two cleaning approaches:

- **Suppressed combustion** — gas is collected as fuel after partial cleaning
- **Open combustion** — gas is combusted in a [waste-heat boiler](/glossary/waste-heat-boiler) and the products cleaned in an ESP or baghouse

## Cleaning targets

- **Primary BOF baghouse hopper** — fine iron-oxide dust
- **Secondary BOF baghouse** — fume capture during charging, tapping and slag operations
- **Waste-heat boiler convective pass** (open-combustion designs)

[Sonic horns](/glossary/sonic-horn) on BOF baghouse hoppers are increasingly specified to defend against the bridging risk associated with fine, hot iron-oxide dust.

## Related terms

- [Electric arc furnace (EAF)](/glossary/electric-arc-furnace)
- [Baghouse](/glossary/baghouse)
- [Waste-heat boiler](/glossary/waste-heat-boiler)