Steel is made through many process routes that balance raw materials, energy, cost, and emissions. For learners from basic to advanced levels, it helps to see the map from traditional ironmaking to modern direct routes. This guide explains the Top 10 Steelmaking Routes from BF BOF to DRI EAF in a clear, structured way, so you can compare inputs, steps, and outcomes. We cover integrated plants, mini mills, smelting reduction, and the rising role of hydrogen ready pathways. By the end, you will understand where ore, coal, natural gas, scrap, and electricity fit, and how each route affects quality, flexibility, and footprint.
#1 BF to BOF Integrated Route
The classic integrated path starts with sinter and pellets plus coke in a blast furnace that produces hot metal at high temperature. A basic oxygen furnace then converts the carbon rich iron into steel using high purity oxygen, fluxes, and stirring for rapid refining. Strengths include very high throughput, wide grade capability, and stable quality for automotive sheets and plate products. Weaknesses are high capital cost, dependence on coking coal, and significant carbon emissions. Continuous casting and hot rolling complete the route with strong productivity and good surface quality.
#2 Scrap Based EAF Mini Mill
This flexible route melts recycled steel scrap in an electric arc furnace using electricity, oxygen lancing, and carbon for foamy slag practice. Lime, alloys, and fluxes adjust chemistry, followed by ladle treatments for cleanliness and casting to billets or slabs. Strengths include lower capital intensity, fast start and stop cycles, and strong circularity benefits. Limits appear when prime scrap is scarce or when ultra low residual grades are needed. Modern plants use digital control, foamy slag, and high efficiency transformers. They often pair with continuous casters to deliver long products and increasingly flat products.
#3 Gas Based DRI to EAF
Shaft furnaces such as Midrex or Energiron reduce iron ore pellets with reformed natural gas to make direct reduced iron at high metallization. Hot DRI or briquetted HBI is charged to an EAF, often together with scrap, improving control over tramp elements and nitrogen pickup. Benefits include lower carbon footprint than coke based iron and reliable virgin iron units when scrap quality is uneven. Key needs are pipeline grade gas, reforming, oxygen for the EAF, and pellet quality. Plants favor regions with gas abundance, seaborne pellet access, and power systems that can handle large furnaces.
#4 Coal Based DRI to EAF
Rotary kiln or rotary hearth processes use non coking coal to reduce calibrated ore into sponge iron for melting. The product feeds an EAF with or without scrap to produce long products and increasingly flat products for regional markets. Advantages include use of local coal and ore without a coking unit or sinter plant. Challenges include higher gangue, lower metallization, and off gas handling to meet environmental rules. Quality upgrades rely on better ore sizing, coal selection, and secondary refining. This route is common where gas is limited, power is available, and demand is growing.
#5 COREX Smelting Reduction with BOF or EAF
COREX makes hot metal without coke ovens by using non coking coal and pellets in paired reactors that generate reducing gas and a melter gasifier. The product can go to a BOF converter or be cast as hot metal for later melting in an EAF. Advantages include removal of the coking step, lower emissions than traditional blast furnaces, and potential use of local coal types. Constraints include high oxygen demand, complex gas systems, and relatively large scale. Many plants export the rich export gas to power or DRI units, improving overall site integration and efficiency.
#6 HIsmelt Smelting Reduction to EAF
HIsmelt injects fine ore and coal directly into a molten iron bath where rapid smelting and intense mixing occur. The process produces hot metal with low phosphorus pickup and creates a top off gas suited for power generation or for pre reduction of burden. The hot metal can be granulated or charged to an EAF for steelmaking with tight control. Benefits include ability to use fines, a compact footprint, and lower coke dependence. Issues include oxygen needs, refractory wear, and limited commercial references compared with blast furnaces. Still, it offers promising flexibility for certain ore types.
#7 BF BOF with Low Carbon Enhancements
Even traditional integrated works can cut emissions with top gas recycling, high pulverized coal or natural gas injection, coke dry quenching, and improved burden preparation for permeability. Additional steps include hot stoves heat recovery, slag valorization into cement, and power from pressure recovery turbines on the furnace gas. In steelmaking, secondary metallurgy and efficient casting reduce rework and yield loss across the complex. Some sites pilot carbon capture on blast furnace gas for later storage or use. Combining these measures can trim emissions meaningfully while protecting capacity and product range.
#8 Hybrid EAF with High HBI Ratio
Many producers blend premium HBI with clean scrap in the EAF to hit demanding sheet and bar grades while keeping residuals low across heats. Continuous charging of hot DRI from a nearby shaft furnace further cuts energy use, power peaks, and tap to tap time in practice. Ladle furnace and vacuum units handle precise decarburization, desulfurization, and inclusion control before caster. This route offers a bridge between pure scrap and full ore based ironmaking. It supports flexible operations that follow market cycles while steadily improving quality through better charge control and digital process tuning.
#9 Hydrogen Ready DRI to EAF
Gas based DRI plants can stepwise increase hydrogen in the reducing gas, moving from natural gas toward pure hydrogen as supply grows over time. With green hydrogen and renewable power, this pathway can slash direct emissions, especially when hot charging limits electricity needs at the furnace. Critical enablers are abundant low cost hydrogen, high grade DR pellets, water management, and grid stability around large EAFs. Early projects prove the metallization and carbon control are achievable. Policy support, long term power contracts, and offtake agreements help de risk investment and speed industrial deployment.
#10 EAF Thin Slab Casting and Rolling
Advanced mini mills couple EAF melting with compact strip production lines that cast a thin slab and roll it directly to hot coil in a single flow. Advantages are short process time, lower energy per ton, and strong cost positions for commodity flat products that serve regional markets. Grade ranges now include many automotive and API steels through better metallurgy and strict process control. Limits remain for the cleanest interstitial free or electrical steels. Still, this route has redefined competitive baselines by combining efficient melting, near net casting, and streamlined hot rolling.