High-Speed Continuous Casting: Unlocking Over 10,000 Tons per Day in Modern Steelmaking

 In modern steel plants, continuous casting is no longer just a link between steelmaking and rolling—it is the key factor that determines the capacity of the entire production line.

As new steelmaking systems set ambitious targets of over 10,000 tons of daily steel output, the continuous casting process must evolve from traditional “stable operation” to an integrated model defined by high speed, high quality, and long service life.

For large-scale systems producing more than 10,035 tons per day, stable casting speed and high equipment availability are critical to overall performance.

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From Stable Casting to High-Speed Casting

Increasing casting speed brings clear productivity gains, but also higher technical challenges:

• A 0.1 m/min speed increase significantly raises demands on

  • mold level stability

  • uniform billet solidification

  • mechanical precision of equipment

Efficiency improvement is not just about faster machines—it also means reducing waiting time, minimizing temperature loss, and keeping the entire steelmaking–casting–rolling process synchronized.

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Optimizing the Secondary Cooling System

The secondary cooling zone plays a decisive role in billet and slab solidification, especially at high casting speeds. Traditional experience-based water control is no longer sufficient.

1. Dynamic Cooling Control

A dynamic secondary cooling model was introduced based on:

• real-time casting speed

• steel grade superheat

• solidification end position

For wide slabs and special steels, a strong-to-weak cooling gradient is applied. This keeps slab surface temperature above 900°C in the straightening zone, effectively reducing transverse cracks.

2. Precision Nozzle Design and Monitoring

• High-precision atomizing nozzles ensure uniform water coverage

• Cooling uniformity is controlled within ±5%

• Online monitoring of water pressure, flow, and temperature enables rapid correction within seconds

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Mold Flow Control at High Casting Speeds

The mold is the core of the continuous caster. At high speeds, molten steel flow must be carefully controlled to prevent defects and breakouts.

Key measures include:

• High-performance mold flux with low viscosity and strong lubrication

• Automatic mold level control (ALC) combined with electromagnetic braking (EMBr) to reduce flow impact

• High-frequency, small-amplitude mold oscillation to minimize oscillation marks and improve surface quality

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Standardized Operation and Equipment Reliability

1. Standard Operating Procedures (SOPs)

Clear SOPs are implemented for four critical stages:

• start of casting

• strand connection

• ladle change

• end of casting

Molten steel superheat is strictly controlled within ±5°C, ensuring stable conditions throughout casting.

2. Long-Life Key Consumables (Procurement Focus)

Improving efficiency also depends on component lifespan:

• Submerged Entry Nozzles (SENs): high resistance to erosion and clogging

• Rollers and segments: hardfacing and thermal fatigue–resistant designs extend service cycles

This reduces downtime and supports long continuous casting sequences.

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Toward “Zero Waiting Time” Across the Process

True efficiency comes from system-level coordination, not isolated optimization.

• Constant casting speed stabilizes converter and refining rhythms

• Intelligent scheduling reduces ladle waiting time by over 15%

• Optimized tundish control minimizes head and tail losses

• Overall metal yield increases by more than 0.5%

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Conclusion

Stable high-speed continuous casting is the final step in fully releasing the capacity of a new steelmaking system.

Through:

• refined secondary cooling optimization

• precise mold flow control

• reliable refractory and equipment supply

the production ceiling of 10,035 tons per day was not only exceeded, but a data-driven, digital steelmaking governance system was also established.

For modern steel plants, high-speed continuous casting is no longer optional—it is a strategic capability for sustainable, high-efficiency production.

One stop solution for steelmaking 

Iron Oxide Scale Rolled In and Other Common Rolling Defects

 

Roll-Related Root Causes in Steel Strip Production

In modern hot and cold rolling lines, surface and shape defects in steel strips are rarely caused by a single factor. While steelmaking quality and heating conditions play important roles, the rolling mill roll system is the final and decisive control point that determines whether defects are eliminated or transferred to downstream products.

Below is a practical overview of common rolling defects, analyzed from a process path + rolling mill roll perspective, suitable for production engineers, quality managers, and procurement professionals.

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Iron Oxide Scale Rolled In

Main process steps:
Heating Furnace → Roughing Mill → Finishing Mill Entry

Hot-rolled steel strips typically carry a layer of iron oxide scale, gray-black or reddish-brown in color. The scale may appear as patches or streaks with uneven distribution and varying penetration depths.

At high rolling temperatures, regenerated oxide scale forms rapidly. If reheating time is excessive or the furnace atmosphere is strongly oxidizing, thick oxide layers develop. During rolling, these oxides can be pressed into the steel surface, making them difficult to remove during pickling.

Although oxide scale thickness is influenced by heating regime, steel grade, and rolling temperature range, whether the scale is actually rolled into the strip is determined by roll surface condition.

Key roll-related factors include:

• Excessive surface roughness of roughing mill work rolls

• Insufficient anti-adhesion performance of roll material

• Poor coordination between roll cooling and descaling systems

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Bending (Sickle-Shaped Strip)

Main processes involved:
Roughing Mill / Finishing Mill

Sickle-shaped bending occurs when the strip bends laterally along its length. The fundamental reason is uneven elongation across the strip width.

From a roll perspective, this defect is commonly linked to:

• Insufficient roll profile machining accuracy

• Non-parallel roll gap adjustment

• Uneven wear of roll bearings

• Inadequate compensation for roll thermal expansion

Uneven billet heating and improper reduction distribution further amplify the bending effect during rolling.

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Torn Edge

Main stages:
Intermediate Rolling → Final Rolling

Torn edges appear as severe edge fractures with saw-tooth shapes and metal tearing. This defect is typically the result of combined mechanical and metallurgical factors.

Roll-related contributors include:

• Unreasonable roll edge profile design

• Concentrated roll wear at strip edges

• Stress concentration under low-temperature rolling conditions

When combined with brittle steel chemistry, billet edge cracks, or overheating during reheating, edge tearing becomes more likely.

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Scratches

Main processes:
Finishing Rolling → Cooling → Coiling

Scratches can be longitudinal or transverse:

• Longitudinal scratches often originate in the finishing mill due to roll surface microcracks, adhered hard particles, or misaligned guides.

• Transverse scratches usually form during cooling bed transfer, transportation, or coiling.

Maintaining high surface integrity of finishing mill work rolls is critical for scratch prevention.

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Indentation (Dents)

Main stage:
Finishing Rolling / Before Coiling

Indentations appear as random, non-periodic pits on the strip surface. Common causes include material buildup on work rolls or pinch rolls, oxide scale adhesion, or metal chips embedded in the roll surface.

This defect typically indicates:

• Insufficient roll anti-adhesion performance

• Inadequate cooling and lubrication management

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Roller Printing (Roll Marks)

Main process:
Finishing Mill Stand

Roller printing appears as periodic bright strip-like or patch-like marks without obvious depth variation. Although visually subtle, they signal early roll surface damage.

Typical causes include:

• Improper roll material selection with insufficient hardness

• Early roll fatigue failure

• Iron filings or debris adhered to the roll surface

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Uneven Thickness

Main process:
Entire Finishing Rolling Section

Thickness deviations may occur both longitudinally (head–middle–tail) and transversely (edge–center).

From the roll system perspective, key causes are:

• Unreasonable roll configuration

• Elastic bending deformation of rolls

• Severe wear of work rolls or backup rolls

High mill stiffness and effective roll shape control are essential for stable thickness accuracy.

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Scarring (Callusing / Scabs)

Main processes:
Intermediate Finishing → Final Finishing Rolling

Scarring appears as irregular tongue-shaped or fish-scale-like raised flakes. Some are rooted and difficult to remove, while others are loosely attached.

Direct roll-related causes include:

• Roll surface defects such as chipping, pinholes, or material loss

• Metal buildup on roll surfaces

• Repeated magnification of roll surface pits during multi-pass rolling

Scarring is a classic symptom of roll surface integrity failure.

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Surface Inclusions

Main sources:
Steelmaking → Heating → Rolling

Surface inclusions appear as point-like, block-like, or strip-like non-metallic particles. They are usually caused by poor slag control, ladle contamination, or refractory spalling during reheating, and are not fully removed during rolling.

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Pockmarks (Oxidation Pits)

Main processes:
Heating → Rough Rolling / Finish Rolling

Pockmarks are rough surface patches with pits of varying depth. Severe cases resemble orange peel. They result from heavy oxidation during heating, where thick oxide layers are pressed into the surface and later detach.

Poor roll surface quality, severe roll wear, and low resistance to oxidation or thermal cracking further aggravate this defect.

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Fold

Main processes:
Rough Rolling / Finishing Rolling

Folds occur when localized metal overlaps and forms a double layer. This is usually caused by mismatched roll profile design and reduction control, often worsened by uneven temperature distribution across the strip.

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Delamination (Layered Structure)

Delamination refers to internal separation of the steel into multiple layers, sometimes with inclusions visible between layers. Root causes include residual shrinkage cavities, concentrated inclusions, and severe chemical segregation in the original billet.

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Erythema (Red Spots)

Main processes:
Heating → Initial Rolling

Erythema appears as reddish spots with certain penetration depth. It is caused by furnace ash or unremoved red oxide scale being pressed into the strip surface during early rolling passes.

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Final Thoughts

Across both hot-rolled and cold-rolled steel production, rolling mill rolls act as the final quality gate.
Even when defects originate upstream, roll material selection, surface integrity, profile accuracy, cooling efficiency, and wear control ultimately determine whether defects are suppressed or transferred to the finished strip.

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One-Stop Solution for the Steel Industry
LMM GROUP

Advanced Manufacturing of Heavy Section Mill Rolls and Roll Rings

 

A Long-Term Technical Partner for Global Steel Producers

Introduction

In today’s steel industry, rolling mill performance is increasingly defined by roll reliability, metallurgical consistency, and lifecycle cost, rather than unit price alone. For steel producers operating section mills, plate mills, and hot strip mills, selecting the right roll supplier directly impacts mill availability, product quality, and total operating cost.

Founded in 2003, LMM GROUP Roll Manufacturing has positioned itself as a specialized producer of large and heavy rolling mill rolls and roll rings, serving steel plants across North America, Europe, and Asia. With a clear focus on medium-to-large roll segments, LMM supports steelmakers seeking long campaign life, stable performance, and reduced unplanned downtime.

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Company Background and Strategic Positioning

With over 20 years of metallurgical manufacturing experience, LMM GROUP has grown into one of China’s most technically capable roll manufacturers.

Key facts at a glance:

• Established: 2003

• Annual capacity: >90,000 metric tons

• Product focus: Large section mill rolls, roll rings, and hot strip mill work rolls

• Strategic direction: High-load, long-life, high-stability roll solutions

Rather than competing in low-end or commodity roll markets, LMM has deliberately focused on large-diameter, high-weight, and complex-pass rolls, where metallurgical control and process stability are critical.

In recent years, the company has expanded into:

• Hot strip mill work rolls

• Forged backup rolls (Phase II expansion)

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Core Product Portfolio

1. Section Mill Rolls (Long Product Rolling)

Section mill rolls remain LMM’s core product line and are widely used in rolling lines for:

• H-beams

• I-beams

• Channels

• Angles

• Rails

Technical range:

• Roll diameter: Ø600 – Ø1800 mm

• Single roll weight: 3 – 50 tons

Section rolling imposes non-uniform stress distribution, complex pass geometry, and severe thermal cycling. LMM addresses these challenges through:

• Optimized alloy systems

• Controlled solidification during casting

• Precisely engineered heat treatment curves

Resulting performance advantages:

• Improved resistance to thermal cracking

• High wear resistance under heavy rolling loads

• Excellent dimensional stability over long rolling campaigns

These characteristics translate directly into extended roll life and fewer mill stoppages.

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2. Roll Rings (Centrifugally Cast)

LMM produces roll rings primarily using advanced centrifugal casting technology, ensuring high density and metallurgical soundness.

Specifications:

• Outer diameter: Ø550 – Ø1800 mm

• Minimum inner diameter: 300 mm

Key advantages:

• Dense and uniform microstructure

• Strong metallurgical bonding between working layer and core

• Excellent fatigue resistance

Centrifugal casting is especially suitable for large-diameter roll rings, where structural uniformity and crack resistance are critical for high-load operation.

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3. Hot Strip Mill Work Rolls

LMM GROUP currently supplies cast work rolls for hot strip mills, supporting modern high-capacity rolling lines.

Application range:

• Mill width: 1250 – 2250 mm

Reference customer:

• Gerdau (USA) – long-term supply relationship

These work rolls meet stringent requirements for:

• Surface quality

• Thermal stability

• Consistent hardness depth

They are designed for stable operation in continuous hot rolling environments.

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Manufacturing Capability: Full Process Control

LMM operates a fully integrated production system, covering melting, refining, casting, heat treatment, and machining.

Maximum capabilities:

• Single-piece weight: 150 tons

• Maximum roll diameter: 2.5 meters

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Melting and Secondary Refining

The melting shop is equipped with 15 medium-frequency induction furnaces, allowing precise matching between furnace size and roll weight.

Furnace configuration:

• 3 t × 2 units

• 5 t × 3 units

• 8 t × 3 units

• 12 t × 5 units

• 20 t × 2 units

This flexible setup ensures:

• Stable superheat control

• Optimized alloy dissolution

• Improved energy efficiency

A 60-ton Ladle Furnace (LF) provides:

• Argon stirring

• Deoxidation and desulfurization

• Precise alloy adjustment

This stage is critical for minimizing non-metallic inclusions and dissolved gases, especially in large-section rolls.

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Advanced Centrifugal Casting Technology

Centrifugal casting is a core strength of LMM.

Equipment overview:

• 11 centrifugal casting machines

  • 8 horizontal machines (standard rolls and roll bodies)

  • 1 vertical machine (short and special geometries)

  • 2 disc-type machines (large roll rings and disc components)

This setup enables centrifugal castings up to 2.5 meters in diameter, ensuring:

• Uniform working layer thickness

• Excellent shell-core bonding

• High metallurgical integrity

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Heat Treatment and CNC Machining

Heat treatment:

• 162 heat treatment furnaces

• Customized heating, soaking, and cooling curves for each roll grade

• Precise control of microstructure and hardness depth

Machining:

• Predominantly CNC-based equipment

• High accuracy in complex pass geometries

• Consistent surface finish and dimensional repeatability

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Quality Assurance and Inspection

LMM applies a defect-prevention philosophy, recognizing that even minor defects can lead to catastrophic rolling incidents.

Inspection system:

• LISMAR Automatic Roll Inspection System (Netherlands)

Integrated NDT methods:

• Eddy Current Testing (ET): surface micro-cracks

• Ultrasonic Testing (UT): internal defects

• Surface Wave Testing (SW): near-surface integrity

On-Site Verification Example

During a recent technical audit, ultrasonic testing was conducted on an as-cast roll prior to heat treatment. Results confirmed exceptional internal density and homogeneity, demonstrating that roll quality is fundamentally established during melting and casting, not corrected afterward.

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Phase II Expansion: Forged Backup Rolls

To meet growing demand for high-end products and reduce reliance on imported backup rolls, LMM is completing its Phase II expansion project.

Commissioning target: End of March (current year)

Key new equipment:

• 50-ton Electric Arc Furnace (EAF)

• 100-ton VD Vacuum Degassing Furnace

The VD system enables ultra-low hydrogen and oxygen levels, which are mandatory for forged backup roll production.

New capabilities:

• High-quality cast ingot production

• Planned launch of forged backup roll manufacturing

• Ability to supply complete roll packages (work rolls + backup rolls)

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Global References and Long-Term Vision

LMM products are already in long-term service at leading steel producers, including:

• Hyundai Steel (Korea)

• POSCO Vietnam

• Gerdau (USA)

These references demonstrate stable performance under demanding industrial conditions. Building on its success in North America and Southeast Asia, LMM aims to become a long-term technical partner for global steel producers.

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Conclusion

From its establishment in 2003 to its full-scale upgrade in 2026, LMM GROUP Roll Manufacturing has remained committed to one core principle:

Data-driven metallurgy and quality-first manufacturing.

Whether delivering 2.5-meter centrifugal cast rolls or producing ultra-clean steel through 100-ton VD refining, LMM continues to provide reliable, high-performance rolling solutions for the modern steel industry.

Steel Procurement in 2026: From Unit Cost to Lifecycle Value

 

Introduction

As 2026 unfolds, the global steel industry is approaching a structural inflection point. China’s new export licensing regime for industrial components—effective January 1, 2026—combined with the European Union’s Carbon Border Adjustment Mechanism (CBAM) entering its first settlement phase, is reshaping how steel producers evaluate risk, cost, and long-term competitiveness.

For procurement and operations teams in Europe, North America, and Southeast Asia, the traditional purchasing logic of “lowest unit price” is rapidly being replaced by a new metric: maximum lifecycle efficiency under regulatory pressure.

1. The “China Factor” in 2026: Why spare-parts security can no longer be taken for granted

For more than a decade, global steelmakers have relied heavily on China-sourced metallurgical components—including rolling mill rolls, copper mould tubes, and refractory products—to support primary and secondary steelmaking operations.

Beginning in 2026, however, China’s export control framework requires manufacturers of certain metallurgical components to pass enhanced compliance reviews covering quality systems, environmental performance, and product traceability before export licenses are granted.

Impact:
Low-cost, low-performance components are rapidly exiting the international market—not due to price, but due to compliance failure.

Strategic implication:
Overseas steel plants must proactively partner with Chinese suppliers that possess:

• Stable export qualifications

• Proven long-term supply reliability

• Documented performance under high-load operating conditions

In this environment, investment in high-performance copper mould tubes and premium rolling mill rolls is no longer a discretionary upgrade—it is a risk-mitigation strategy against production interruption.

2. CBAM 2026: When consumables become carbon liabilities—or carbon-saving assets

Under CBAM’s 2026 implementation phase, inefficiencies that were previously absorbed as “operational loss” are now directly monetized as carbon cost.

Every megawatt of wasted thermal energy and every ton of downgraded or scrapped steel increases a plant’s effective carbon exposure.

Refractory materials as thermal efficiency assets

In the era of low-carbon steelmaking, furnace lining performance has become a measurable economic indicator. High-density, low-thermal-conductivity refractory bricks reduce heat loss, lower electricity and fuel consumption, and directly decrease emissions per ton of steel.

From a CBAM audit perspective, improved thermal insulation translates into a reduced embedded carbon footprint—improving compliance outcomes without process redesign.

Copper mould tubes and first-pass yield

In continuous casting, mould performance has a direct impact on surface quality and defect rates. Substandard copper mould tubes increase the risk of longitudinal cracks, breakout incidents, and downstream rejection.

By 2026, defective output is no longer just a material loss—it represents wasted carbon allowances. High-precision copper mould tubes improve first-pass yield, which remains the most effective way to reduce Scope 1 emissions in casting operations.

3. Fighting inflation through extended service life

Persistently high global energy prices and skilled labor shortages have doubled downtime-related costs compared to five years ago.

Rolling mill roll performance

Work roll replacement is labor-intensive and often requires full production stoppage. Transitioning to high-speed steel (HSS) or high-chromium alloy rolls with superior wear resistance can extend rolling campaigns by 20–30%.

A 15% increase in component service life delivers more than proportional value:

• Lower replacement frequency

• Reduced maintenance hours

• Fewer unplanned shutdowns

• Lower operational risk exposure

In 2026, lifecycle extension is one of the most effective tools for cost control.

Conclusion: Rethinking metallurgical procurement in 2026

The era of disposable metallurgical consumables is over.

Whether evaluating refractory linings for electric arc furnaces or rolls for high-speed rolling mills, procurement decisions in 2026 must be based on a component’s ability to:

• Reduce energy consumption

• Extend service life

• Support regulatory and carbon compliance

• Perform reliably in high-cost operating environments

As a global supplier of critical steel mill components, LMM GROUP supports steel producers in navigating the operational and regulatory complexities of 2026. Our solutions are engineered for the green transition and designed to deliver durability where downtime and carbon costs are no longer acceptable.

Reprinted from LMMGROUP

Influence of Carbon Content on the Properties of Low-Carbon Magnesia-Carbon Bricks

 1. Introduction

With the continuous development of the steel industry, the proportion of ultra-low carbon steel in steelmaking is steadily increasing. Traditional magnesia-carbon bricks, which contain relatively high carbon content, are associated with problems such as excessive heat loss, carbon pickup in molten steel, and increased environmental burden. As a result, low-carbon magnesia-carbon bricks have gradually become a major research focus.

However, reducing carbon content inevitably leads to deterioration in high-temperature performance, particularly thermal shock resistance and slag corrosion resistance. It is well known that lowering the carbon content reduces thermal conductivity while increasing elastic modulus, thereby worsening thermal shock stability. In addition, reduced carbon content increases the wettability of the brick by slag and molten steel, resulting in lower slag resistance and higher permeability.

In recent years, Japan has achieved significant progress in the development of low-carbon magnesia-carbon bricks through nanotechnology. This study systematically investigates the influence of different carbon contents on the physical and high-temperature properties of magnesia-carbon bricks. The objective is to identify an optimal carbon range suitable for smelting different steel grades, reduce environmental impact, and improve resource utilization efficiency.

2. Experimental Procedure

2.1 Raw Materials

The experiment used the following raw materials:

• 97% MgO fused magnesia

• Flake graphite (<196 μm)

• Aluminum powder

• Liquid thermosetting phenolic resin as binder

The compositions of the samples are listed in Table 1.

2.2 Sample Preparation

Aggregates and resin were first wet-mixed for 1–2 minutes, after which fine powders were added and mixed for approximately 40 minutes. The mixture was sealed and aged for 12 hours. Specimens were then molded under a pressure of 0.2 MPa per unit area into:

• Cylindrical samples: Ø50 mm × 50 mm

• Strip samples: 25 mm × 40 mm × 130 mm

All specimens were dried at 200 ℃ for 24 hours before testing.

Table 1 Composition of Magnesia-Carbon Brick Samples (wt.%)

3. Analysis of Experimental Results

3.1 Physical Properties

As carbon content increased, the bulk density of the samples generally decreased. The maximum bulk density of 3.13 g·cm⁻³ was observed at 4% carbon content. Between 6% and 10% carbon, bulk density showed little variation; however, above 10%, a significant decline occurred.

The apparent porosity exhibited the opposite trend, reaching a minimum at 4% carbon content. When carbon content exceeded 10%, porosity increased rapidly.

3.2 Mechanical Properties

The room-temperature compressive strength decreased with increasing carbon content. Carbon-free samples showed the highest strength (112.1 MPa). When carbon content was between 2% and 6%, compressive strength remained relatively stable; beyond 6%, it declined sharply.

High-temperature flexural strength is a key indicator of resistance to thermal stress, impact, abrasion, and slag attack. With increasing carbon content, the flexural strength exhibited a zigzag trend. The highest value (8.90 MPa) was observed at 2% carbon content, while the lowest (7.77 MPa) occurred at 4%. Between 6% and 18% carbon, flexural strength first decreased and then increased.

3.3 Thermal Shock Resistance

Thermal shock stability was evaluated by measuring the flexural strength loss rate after three water-cooling cycles at 1100 ℃.

As carbon content increased, the loss rate initially decreased and then increased. Sample #1 showed the highest strength loss, while Sample #5 exhibited the lowest. Samples containing 2–6% carbon showed minimal spalling after thermal shock. When carbon content exceeded 14%, severe surface oxidation caused significant peeling and spalling.

Lower carbon content resulted in greater thermal stress due to mismatch in thermal expansion, leading to higher flexural strength loss.

3.4 Oxidation Resistance

At 1600 ℃ for 3 hours, oxidation resistance varied with carbon content. Samples with excessive or insufficient carbon showed severe oxidation. Samples with 4–10% carbon formed relatively dense decarburized layers, improving oxidation resistance. Overall, carbon content had a limited effect on oxidation resistance, but both extremes were detrimental.

3.5 Slag Resistance

Slag erosion tests were conducted at 1600 ℃ for 3 hours using slag with the composition shown in Table 2.

Table 2 Slag Composition (wt.%)

Slag penetration occurred mainly along periclase grain boundaries. Sample #4 exhibited the best slag resistance, with minimal adhesion and no obvious decarburized layer. Periclase grain growth and silicate phase formation effectively blocked further slag penetration.

Samples with higher carbon content showed increased graphite oxidation, leading to porous decarburized layers and reduced slag resistance. Although high-carbon bricks generally resist slag erosion, surface decarburization ultimately accelerates structural damage.

4. Conclusions

1. Increasing carbon content leads to a reduction in bulk density and compressive strength of magnesia-carbon bricks.

2. Optimal overall performance—high-temperature flexural strength, thermal shock resistance, slag resistance, and oxidation resistance—is achieved when carbon content is 6–8%.

3. Magnesia-carbon bricks with 6–8% carbon content are recommended for the smelting of low-carbon and ultra-low carbon steels.

How to Control Blowing Lance in Converter Steelmaking?

 Five-Stage Lance Position Control (Low–High–Low–High–Low)

The five-stage lance position method is not a rigid rule but a guiding principle for BOF/LD blowing control, aimed at coordinating stirring, slag formation, temperature rise, FeO control, and carbon–oxygen reaction.

① Low (Initial strong stirring)
Lower the lance 100–200 mm below normal at blow start to intensify stirring, accelerate scrap melting, eliminate dead zones, and build early bath temperature. Use higher oxygen pressure (~0.9 MPa) for 60–90 s, then add slag materials in small, frequent batches. Early dolomite addition (MgO) promotes slag melting and early dephosphorization.

② High (Slag formation & heating)
Raise the lance to normal or slightly higher to promote slag melting and uniform heating. Maintain FeO at ~20–25% to ensure lime dissolution. This stage may be longer in low iron-consumption practice. Slag must be fully melted before adding the second batch; excessive lance height leads to low bath temperature, poor reactions, and high-FeO splashing.

③ Low (Suppress FeO & splashing)
As temperature and FeO rise, conditions for splashing emerge. Lowering the lance strengthens the carbon–oxygen reaction, consumes FeO, suppresses splashing, accelerates decarburization, and stabilizes bath stirring.

④ High (Intense reaction control)
This is the most difficult stage. FeO is rapidly consumed, and improper lance adjustment can cause dry slag, violent splashing, phosphorus reversion, and equipment damage. Continuous flame observation is essential; adjust the lance before the flame turns vertical to maintain fluid slag without splashing.

⑤ Low (End-point control)
Gradually lower the lance to carbon-blowing position for ≥40 s to homogenize temperature and composition and reduce slag FeO. Maintain a “soft” flame to avoid lance damage. Once endpoint carbon and temperature meet requirements, raise the lance and finish blowing.

Key Misconceptions & Operational Points

Defects are not simply due to insufficient slag amount

• Unmelted lime = ineffective lime → poor dephosphorization/desulfurization.

• Late melting of oversized or abnormal scrap introduces harmful elements at the end.

Typical 12-minute blow time allocation (reference only)

• Phase 1: 1.5–2 min

• Phase 2: 2–4 min

• Phase 3: 2–3 min

• Phase 4: ~3 min

• Phase 5: ~2 min
  Actual timing must be adjusted by flame and furnace response.

Correct handling of splashing

• High-temperature splashing: add material briefly, then promptly lower the lance.

• Low-temperature splashing: do not raise the lance or add blindly; instead reduce oxygen pressure, add small batches, and stabilize the carbon–oxygen reaction

Core principle
The blow is short but highly dynamic. Operators must understand flame–reaction relationships, make proactive adjustments, and use lance position to control the flame, not chase it. The five-stage method reflects a trend, not a rigid formula—skillful flexibility is the key to stable, high-quality steelmaking.

LMM GROUP ONE STOP SOLUTION FOR STEELMILL

Steelmaking process

The steelmaking process involves producing steel from iron ore. Essential impurities such as nitrogen, silicon, phosphorus, sulfur, and excess carbon are removed from the base iron. Other elements such as manganese, nickel, chromium, and vanadium are added to create different grades of steel.

The basic infrastructure for steel manufacturing includes coke ovens and coal chemical plants, sintering plants, blast furnaces, steelmaking plants and rolling mills. This can be done through basic oxygen furnaces or electric arc furnaces.

In the first method, hot metal from the blast furnace is fed into a basic oxygen furnace after pretreatment and impurities removal. Molten steel is produced in liquid form and impurities are removed in gaseous form and as slag.

In the electric arc furnace process, scrap steel is melted using an electric arc generated by graphite electrodes. This can be used as ingots or fed into continuous casting processes. Gases and synthetic gases are also used in modern steelmaking. These are alternatives to blast furnace steelmaking methods that use oxygen.

Applications include blast furnace or coke gas, Corex gas, oxygen, steam, nitrogen and hydrogen. Acids are used in pickling plants to clean the surface of steel plates to remove rust.
Cooling water, steam and hot water are used at various locations throughout the steel plant.

Steel mills primarily use large butterfly valves for gas applications, or large gate and double-plate check valves. Where high-temperature applications are involved, metal-seated triple-offset valves are used. Gate, globe, check, and ball valves are smaller and suitable for a variety of utility applications.