Electrolytic Manganese Flakes For Steelmaking Deoxidation: A Practical Guide For Melt Shops

Direct answer: Electrolytic manganese flakes can participate in steel deoxidation while increasing the manganese content of molten steel. However, they are not normally used as the only deep deoxidizer. In most melt shops, they are used together with silicon, aluminum, or other deoxidizing elements. Their main value lies in precise manganese adjustment with limited carbon, silicon, phosphorus, sulfur, and other unwanted additions.

What Role Do Electrolytic Manganese Flakes Play in Steelmaking Deoxidation?

After being added to molten steel, electrolytic manganese flakes usually perform three functions:

1.Participating in molten steel deoxidation

2.Adjusting the final manganese content

3.Changing the form in which sulfur exists in the steel

How Does Electrolytic Manganese Participate in Molten Steel Deoxidation?

After manganese enters the molten steel, it can react with dissolved oxygen:

The generated MnO may enter the slag or combine with oxides such as SiO₂ and Al₂O₃ to form complex inclusions.

However, manganese is not a strong deoxidizing element. Compared with aluminum, manganese has a limited ability to reduce dissolved oxygen when used alone. For steel grades requiring a low final oxygen content, melt shops commonly use one of the following approaches:

• Combined deoxidation with manganese and silicon
• Deep deoxidation with aluminum before manganese adjustment
• Final manganese trimming with electrolytic manganese flakes

The practical value of electrolytic manganese flakes is therefore to participate in deoxidation while precisely increasing manganese, rather than completing the entire deoxidation process by themselves.

How Do Electrolytic Manganese Flakes Adjust the Final Mn Content?

Manganese that is not oxidized dissolves in the molten steel and increases the final Mn content.

When calculating the required addition, the melt shop should consider:

• Current Mn content of the molten steel
• Target Mn content range
• Actual purity of the electrolytic manganese flakes
• Oxidation loss of manganese
• Historical manganese recovery
• Mn introduced by ferromanganese, silicomanganese, and scrap
• Further refining and reoxidation losses

Electrolytic manganese flakes are particularly useful for small composition corrections during LF refining or other stages where the target manganese range is narrow.

Can Manganese Complete Steel Desulfurization?

Manganese cannot replace slag desulfurization.

After entering molten steel, manganese can combine with sulfur to form MnS, reducing the harmful effect of low-melting-point FeS on hot-working performance. Its main function is to change the form of sulfides rather than directly remove sulfur from molten steel.

Actual desulfurization still depends on:

• Slag basicity
• Slag oxidation level
• Molten steel temperature
• Slag–steel stirring
• Refining time
• Slag volume and slag–steel contact conditions

Manganese can help control sulfur and improve hot-working performance, but it cannot complete deep desulfurization by itself.

Can Electrolytic Manganese Flakes Be Used as the Only Steelmaking Deoxidizer?

For production requiring a low final oxygen content, electrolytic manganese flakes are generally not used as the only deoxidizer.

The main reasons include:

• Manganese has weaker deoxidizing ability than aluminum
• High dissolved oxygen causes more manganese to oxidize into MnO
• Oxidizing slag can further reduce manganese recovery
• MnO may become part of complex inclusions
• Subsequent reoxidation may increase the oxygen content again

The type of deoxidizer, addition sequence, addition position, and slag condition all affect the final deoxidation result and inclusion composition.

Why Use Electrolytic Manganese Flakes Instead of Ferromanganese?

Ferromanganese and silicomanganese remain suitable for large-scale manganese addition in conventional steel grades. Electrolytic manganese flakes are more suitable when carbon, silicon, and impurity pickup must be controlled more closely.

Electrolytic manganese flakes are more suitable when:

• The carbon content of the steel should not increase significantly
• Excess silicon pickup should be avoided
• Phosphorus, sulfur, selenium, or other impurities are strictly limited
• The final Mn range is narrow
• Composition trimming is required during the later refining stage
• Conventional ferromanganese cannot meet the target chemical composition

When an ordinary steel grade only requires a large manganese addition and can tolerate the elements introduced by ferromanganese, replacing all ferromanganese with electrolytic manganese flakes may not be economically necessary.

When Should Electrolytic Manganese Flakes Be Added to Molten Steel?

There is no fixed addition time that applies to every steel plant. The actual stage should be determined according to the steel grade, molten steel oxygen content, slag condition, and available production equipment.

Adding Electrolytic Manganese Flakes During Tapping

During tapping, the steel stream can help melt and disperse the electrolytic manganese flakes, making this stage suitable for relatively large manganese adjustments.

The main operating risks include:

• High molten steel oxygen content can increase manganese loss
• Excess converter or electric furnace slag carryover can cause manganese reoxidation
• Flakes landing on the slag surface may oxidize before entering the molten steel
• Early addition increases contact time with oxidizing slag

Slag control, addition position, and initial oxygen content should therefore be checked before adding electrolytic manganese during tapping.

Adding Electrolytic Manganese Flakes During LF Refining

LF refining is usually more suitable for precise Mn adjustment, especially after preliminary deoxidation has been completed.

The main advantages include:

• The addition amount can be calculated from sampling results
• Molten steel oxygen activity is usually lower than during early tapping
• Argon stirring supports melting and homogenization
• Manganese recovery is easier to stabilize
• The final composition range is easier to control

Sufficient melting and stirring time should be provided before another sample is taken to confirm the composition.

Small Electrolytic Manganese Trim Additions Before Continuous Casting

For steel grades with a narrow final Mn range, a small correction can be made before continuous casting.

However, adding too late may cause:

• Incomplete melting of the electrolytic manganese flakes
• Localized high Mn concentration
• Insufficient homogenization time
• Unrepresentative sampling results
• Reduced recovery due to reoxidation

The closer the addition is to continuous casting, the more carefully the quantity, stirring time, and reinspection procedure should be controlled.

How Is the Required Electrolytic Manganese Addition Calculated?

The planned addition can be estimated using a mass-balance calculation:

For example:

• Molten steel weight: 50 tons
• Current Mn: 0.30%
• Target Mn: 0.50%
• Required Mn increase: 0.20%
• Electrolytic manganese purity: 99.7%
• Expected manganese recovery: 95%

The theoretical planned addition is approximately 106 kg.

This calculation should not be treated as a fixed addition for every heat. Actual production adjustments should also consider:

• Initial oxygen content of the molten steel
• FeO and MnO levels in the slag
• Addition stage
• Molten steel temperature
• Stirring time
• Historical recovery data
• Mn introduced by other materials
• Subsequent refining time

The target Mn increase is the difference between the target value and the current measured value, not the total Mn content of the finished steel.

What Factors Reduce Electrolytic Manganese Recovery?

Manganese recovery is not a fixed value. Noticeable fluctuations may occur between heats even when the same steel grade and electrolytic manganese specification are used.

When recovery remains below expectations, the melt shop should not immediately increase the addition amount for every heat.

The following points should be checked first:

• Whether slag control is stable
• Whether slag FeO is too high
• Whether the flakes actually enter the molten steel
• Whether the addition timing is appropriate
• Whether the molten steel temperature is sufficient
• Whether stirring and homogenization time are adequate

How Do Electrolytic Manganese Flakes Affect Inclusions in Steel?

Electrolytic manganese flakes form MnO when they participate in deoxidation. They should therefore not be described as a material that automatically reduces all inclusions.

Different deoxidation systems may produce:

• MnO inclusions
• MnO-SiO₂ complex inclusions
• MnO-SiO₂-Al₂O₃ complex inclusions
• Complex inclusions associated with subsequent MnS precipitation

Under manganese–silicon combined deoxidation conditions, inclusion composition can be adjusted by controlling Mn, Si, Al, and slag chemistry. The final result also depends on:

• Initial oxygen content of the molten steel
• Addition sequence of Mn, Si, and Al
• Top-slag oxidation level
• Molten steel temperature
• Refining time
• Stirring conditions
• Whether reoxidation occurs

Inclusion-control performance should not be evaluated only by the number of inclusions. The following factors should also be reviewed:

• Inclusion composition
• Inclusion size
• Inclusion morphology
• Distribution within the steel
• Agglomeration behavior
• Risk of nozzle clogging
• Effects on casting, rolling, and final steel performance

What Common Problems Occur When Using Electrolytic Manganese Flakes?

Why Is Electrolytic Manganese Recovery Lower Than Expected?

Common causes include high dissolved oxygen, excessive carryover of oxidizing slag, flakes remaining on the slag layer, unsuitable addition timing, and actual recovery being lower than the value used in the calculation.

Improvement efforts should focus on deoxidation practice, slag control, and addition position rather than only increasing the addition amount.

Why Do Electrolytic Manganese Flakes Fail to Melt Completely?

Common causes include:

• Low molten steel temperature
• Excessive single-batch addition
• Insufficient stirring intensity
• Addition position far from exposed molten steel
• Moisture absorption or caking
• Sampling too soon after addition

The problem can be reduced by adding the material in batches, improving the addition position, increasing effective stirring, and allowing sufficient homogenization time.

Why Does the Final Mn Content Exceed the Target?

Possible causes include:

• The original Mn content was not deducted
• Mn introduced by ferromanganese, silicomanganese, or scrap was ignored
• The molten steel weight was estimated incorrectly
• An unsuitable expected recovery value was used
• Sampling was performed before full homogenization
• The analytical sample was not representative

The calculation basis, heat weight, and sampling procedure should be checked before concluding that the electrolytic manganese product caused the deviation.

Which Impurities Should Be Checked in Electrolytic Manganese Flakes?

Procurement specifications should not examine only total Mn content. The following elements should also be controlled:

• Carbon
• Sulfur
• Phosphorus
• Iron
• Silicon
• Selenium

Some electrolytic manganese production routes may use selenium-containing additives. For selenium-sensitive steel grades, the maximum Se content should be written into the purchase specification, with batch-specific test results required.

What Should Melt Shops Check When Purchasing Electrolytic Manganese Flakes?

The physical condition of electrolytic manganese flakes is also important for melt-shop operation.

Severe pulverization, moisture absorption, caking, or contamination may affect:

• Automatic feeding
• Weighing accuracy
• Melting speed
• Addition loss
• Actual manganese recovery

Procurement specifications should therefore confirm chemical composition, flake form, fines ratio, moisture-resistant packaging, and batch identification.

Which Steel Grades Are Suitable for Electrolytic Manganese Flakes?

Electrolytic manganese flakes are more suitable for:

• Precise adjustment of molten steel Mn content
• Limiting additional carbon and silicon pickup
• Strict control of phosphorus, sulfur, selenium, and other impurities
• Small composition corrections during later refining
• Production of low-carbon steel, low-silicon steel, stainless steel, or special alloy steel
• Steel grades where conventional ferromanganese cannot meet the target composition window

Electrolytic manganese flakes may not be the preferred option when:

• Ordinary steel grades require a large manganese addition
• The steel can tolerate carbon and iron introduced by ferromanganese
• The main objective is low-cost conventional alloying
• Deoxidation, slag control, and recovery control are not stable
• The main requirement is conventional manganese–silicon deoxidation

The selection should be based on steel-grade requirements, effective manganese cost, actual recovery, and the difficulty of final composition control.

How Can Melt Shops Stabilize Electrolytic Manganese Performance?

Melt shops should not use one empirical recovery value for every steel grade and every addition stage.

A more reliable approach is to record the following data for each heat:

• Molten steel weight
• Initial Mn content
• Target Mn content
• Actual electrolytic manganese addition
• Addition stage
• Molten steel temperature
• Stirring time
• Slag FeO or another oxidation indicator
• Sampling time after addition
• Final Mn content
• Actual manganese recovery

After accumulating data from multiple heats, separate recovery models can be established for:

• Tapping-stage additions
• LF-refining additions
• Final trimming before continuous casting
• Different steel grades
• Different electrolytic manganese supply batches

This approach is more effective for reducing heat-to-heat composition fluctuations than simply increasing the addition amount.