When a steel plant or refractory manufacturer is evaluating a natural graphite supplier for steel plants, the decision should involve much more than comparing prices per tonne. Graphite is an important raw material in many steelmaking applications, especially in MgO-C and other carbon-based refractories. Purity, particle size, shape, and batch consistency can affect the performance of the final product.
MgO-C refractories are used in demanding steelmaking environments because of their combination of thermal, mechanical, and chemical properties. Research has examined how graphite content and raw-material characteristics can influence properties such as thermal conductivity, thermal expansion, porosity, and thermal-shock behavior.
For procurement teams, this creates an important question:
What should a steel plant or refractory manufacturer look for when choosing a natural graphite supplier?
The answer involves several connected factors: graphite quality, specification control, testing, batch consistency, supply capacity, packaging, documentation, logistics, and technical support.
A supplier that can consistently deliver the required grade may provide greater practical value than a supplier offering a lower price on a single shipment.
1. Why Natural Graphite Matters in Steelmaking Refractories
Natural graphite is an important carbon-containing raw material in several refractory systems used around steelmaking operations.
One of the best-known examples is the magnesia-carbon (MgO-C) refractory. These refractories are used in demanding areas associated with steelmaking, including furnaces, converters, ladles, and other high-temperature zones.
Graphite can contribute several useful characteristics to refractory systems, including:
- High thermal conductivity
- Low thermal expansion
- Thermal-shock resistance
- Resistance to wetting by many slags
- Carbon contribution to the refractory matrix
- Influence on corrosion and oxidation behavior
Research on MgO-C refractories has shown that changes in graphite content and characteristics can influence thermal and mechanical properties. However, more graphite is not automatically better. Excessive carbon can also introduce disadvantages, including increased oxidation susceptibility and heat loss.
This is why graphite selection needs to be considered as part of the overall refractory formulation.
The objective is not simply to purchase high-carbon graphite.
The objective is to obtain graphite with the right chemistry, morphology, and particle-size distribution, consistently delivered from batch to batch.
2. What Should a Natural Graphite Supplier Provide?
The term “natural graphite” covers a range of materials. Depending on the application and deposit, suppliers may offer different grades, morphologies, and particle-size distributions.
Products can include:
- Natural flake graphite
- Natural crystalline graphite
- Amorphous natural graphite
- Graphite powder
- Different mesh grades
- Different fixed-carbon grades
- Fine and coarse particle distributions
- Refractory-grade graphite
- Application-specific graphite grades
For steelmaking-related refractory applications, natural flake graphite can be particularly relevant because its morphology and thermal characteristics can influence the behavior of carbon-containing refractory systems.
When requesting a quotation, a buyer should therefore specify the actual material required rather than simply writing:
Natural graphite – 100 MT
A more useful RFQ could state:
Natural flake graphite for refractory application, minimum fixed carbon requirement, maximum ash, controlled moisture, defined particle-size distribution and agreed impurity limits.
This gives the supplier a clear technical target and makes quotations easier to compare.
For buyers evaluating different graphite grades, understanding crystalline graphite grades can also help provide useful context when comparing material characteristics.
3. Graphite Specifications Steel Plants Should Check
Graphite specifications should be defined according to the refractory formulation, production process, and end-use requirements. Parameters such as fixed carbon, ash, moisture, particle size, and chemical impurities should be evaluated against the buyer’s technical requirements. For general information about graphite production, resources, and applications, buyers can refer to the U.S. Geological Survey graphite information
A professional graphite specification should cover both chemical composition and physical characteristics.
Important parameters can include:
| Specification | Why It Matters |
|---|---|
| Fixed carbon | Defines carbon contribution |
| Ash | Indicates inorganic mineral residue |
| Moisture | Affects handling and processing |
| Volatile matter | Can influence processing behavior |
| Particle size | Influences dispersion and packing |
| Flake size | Important for flake-graphite applications |
| Fe₂O₃ | Relevant impurity for refractory chemistry |
| SiO₂ | Can influence high-temperature reactions |
| CaO | Relevant to ash chemistry |
| TiO₂ | May require control in specific formulations |
| Alkalis | Can be relevant to refractory performance |
| Sulfur | Application-dependent impurity |
| Bulk density | Useful for handling and formulation |
| Packaging | Protects material during storage and transport |
The exact limits should be agreed upon according to the customer’s refractory formulation, quality requirements, and applicable standards.
Indian standards and other technical specifications can be useful references, but buyers should verify the current applicable edition rather than relying on an outdated specification. The Bureau of Indian Standards provides a searchable Know Your Standard portal for checking applicable standards.
4. Fixed Carbon vs. Overall Graphite Quality
Fixed carbon is one of the first values procurement teams usually examine when purchasing graphite.
A higher fixed-carbon percentage generally indicates a lower proportion of non-carbon residue. However, fixed carbon alone does not describe the complete quality or performance characteristics of a graphite grade.
Consider two graphite products:
Product A: 95% fixed carbon
Product B: 95% fixed carbon
At first glance, the two products appear identical.
However, they may have different:
- Particle-size distributions
- Flake morphology
- Ash chemistry
- Moisture levels
- Volatile matter
- Iron content
- Silica content
Those differences may influence how the graphite behaves during processing and in the final refractory formulation.
Therefore, procurement teams should avoid selecting graphite using fixed carbon as the only criterion.
A better approach is to evaluate chemical composition, physical properties, morphology, particle-size distribution, and batch consistency together.
5. Why Graphite Purity Matters in MgO-C Refractories
Graphite purity can influence the behavior of carbon-containing refractory systems.
Steelmaking refractories operate under demanding conditions involving:
- Very high temperatures
- Molten steel
- Basic slags
- Thermal cycling
- Mechanical wear
- Oxidizing environments
- Chemical reactions
Mineral impurities in graphite can become part of the high-temperature reaction system within the refractory.
For example, research into MgO-C refractory raw materials has examined the influence of graphite purity and particle-size characteristics on properties such as corrosion resistance, porosity, and thermal behavior.
This is why a serious graphite supplier should be able to provide a clear chemical analysis, rather than simply describing a product as “high purity.”
A buyer should understand:
What is the fixed carbon?
but also:
What makes up the remaining ash?
That second question can be important when the graphite is going into a carefully controlled refractory formulation.
6. Understanding Ash Chemistry in Refractory-Grade Graphite
Ash represents the inorganic residue remaining after carbonaceous material is tested under the relevant conditions.
A buyer may initially focus only on total ash.
For example:
Ash: Maximum 5%
However, two graphite grades with similar total ash can have very different ash chemistry.
The ash may contain different proportions of:
- SiO₂
- Al₂O₃
- Fe₂O₃
- CaO
- MgO
- TiO₂
- Alkali oxides
For refractory manufacturing, these components can have different effects at elevated temperatures.
This is why a technical graphite specification should ideally provide:
Total ash
and, where relevant,
Ash chemistry.
This information allows refractory engineers to assess whether the graphite is compatible with their formulation.
7. Why Particle-Size Distribution Matters in Graphite
Particle size is one of the most important physical characteristics of graphite used in refractory production.
A material consisting entirely of particles of the same size can leave more void space between particles. A carefully controlled particle-size distribution can provide a different packing structure because smaller particles can occupy spaces between larger particles.
The same principle is relevant to refractory formulations.
Research on MgO-C refractories has examined how graphite particle-size distribution can influence characteristics such as porosity and thermal-shock behavior.
Therefore, buyers should not simply ask:
Is it 100 mesh?
Instead, they should request information such as
- Percentage passing the specified sieve
- Percentage retained
- Fine-particle fraction
- Oversize fraction
- Particle-size distribution
- Test method
Understanding how graphite is processed can also help buyers evaluate material consistency. You can read more about the graphite beneficiation process in Odisha.
8. Flake Size and Graphite Morphology in Refractory Applications
Natural flake graphite has a distinctive layered structure, and its morphology can influence the behavior of graphite within a refractory matrix.
Flake characteristics can affect:
- Thermal conductivity
- Thermal expansion
- Thermal-shock behavior
- Lubricity within the matrix
- Microstructure
- Slag interaction
When a refractory formulation has been developed around a particular graphite morphology, changing suppliers without controlling flake characteristics can potentially change the behavior of the final product.
For this reason, a reliable supplier should be able to provide consistent flake characteristics, not simply a consistent fixed-carbon percentage.
9. Certificate of Analysis for Graphite: What Steel Plants Should Check
A Certificate of Analysis (COA) provides documented information about the material supplied.
Depending on the agreed product specification, a COA may include:
- Fixed carbon
- Ash
- Moisture
- Volatile matter
- Particle size
- Flake size
- Fe₂O₃
- SiO₂
- CaO
- Other relevant impurities
- Batch number
A COA becomes more useful when the supplier’s test methods and acceptance criteria are clearly defined.
One important distinction is between
Typical value
and
Guaranteed value.
For example:
Fixed Carbon: 95% typical
is different from:
Fixed Carbon: 95% minimum guaranteed
Procurement teams should understand this difference before comparing suppliers.
A good purchasing specification should clearly state which parameters are guaranteed and which are provided only as typical values.
10. How to Test Graphite Before Supplier Approval
A steel plant or refractory manufacturer should establish an incoming material inspection procedure appropriate to its quality system.
A typical process may include:
Step 1: Document Review
Check:
- Purchase order
- Supplier specification
- COA
- Batch number
- Packing list
Step 2: Visual Inspection
Check for:
- Contamination
- Foreign particles
- Excessive moisture
- Packaging damage
- Unusual appearance
Step 3: Sampling
Take representative samples according to the company’s sampling procedure.
Step 4: Laboratory Testing
Depending on the specification, test:
- Fixed carbon
- Ash
- Moisture
- Volatile matter
- Particle size
- Relevant impurities
Step 5: Compare Against Specification
Determine whether the batch meets the agreed acceptance criteria.
Step 6: Record the Results
Maintain a batch-wise quality record for traceability.
The precise test methods should be agreed between the buyer and supplier and selected according to the applicable specification or standard.
11. Why Batch-to-Batch Graphite Consistency Matters
For industrial graphite users, consistency can be as important as the headline specification.
Suppose a refractory manufacturer develops a successful MgO-C formulation using graphite with:
- Consistent fixed carbon
- Controlled ash
- Stable particle size
- Consistent flake morphology
If the next shipment has the same nominal grade but significantly more fines or different ash chemistry, the raw material has changed even though the product name has not.
That variation may influence:
- Mixing behavior
- Compaction
- Density
- Porosity
- Strength
- Thermal properties
- Corrosion behavior
- Production consistency
This is why supplier qualification should consider variation over time, rather than only one excellent test report.
A supplier should ideally be able to demonstrate that multiple batches remain within the agreed specification.
12. How to Evaluate Graphite Supplier Consistency
Do not judge supplier consistency from a single COA.
Where commercially appropriate, buyers can compare several recent or historical batch analyses.
For example:
| Parameter | Batch 1 | Batch 2 | Batch 3 | Batch 4 | Batch 5 |
|---|---|---|---|---|---|
| Fixed Carbon | — | — | — | — | — |
| Ash | — | — | — | — | — |
| Moisture | — | — | — | — | — |
| Volatile Matter | — | — | — | — | — |
| Particle Size | — | — | — | — | — |
| Fe₂O₃ | — | — | — | — | — |
The objective is not necessarily to find the batch with the highest carbon content.
It is to determine whether the supplier can maintain stable and predictable characteristics over time.
13. Why Steel Plants Should Conduct Graphite Trial Batches
A technical datasheet cannot replace an actual production trial.
Even when two graphite suppliers provide apparently similar chemical analyses, their materials may behave differently during processing.
A controlled qualification trial can evaluate:
- Mixing
- Flow
- Dispersion
- Pressing
- Density
- Porosity
- Strength
- Thermal behavior
- Corrosion resistance
- Final refractory performance
Research into MgO-C refractories demonstrates that changes in graphite content and raw-material characteristics can influence properties such as strength, thermal conductivity, and thermal-shock behavior.
Before replacing a major graphite source, a refractory manufacturer should therefore consider a controlled qualification trial appropriate to its process.
14. Graphite Supply Capacity and Delivery Reliability
Quality is only one part of supplier selection.
Steel plants and large refractory manufacturers also require dependable supply.
A natural graphite supplier for steel plants should be evaluated on factors such as
- Monthly production capacity
- Available stock
- Domestic sourcing
- Import dependency
- Warehouse capacity
- Packaging capacity
- Transportation arrangements
- Lead time
- Emergency supply capability
- Ability to handle repeat orders
A supplier may provide technically suitable graphite but still be unsuitable for a large industrial customer if the required volume cannot be delivered consistently.
For large-volume users, supply planning should ideally include demand forecasting and agreed delivery schedules.
15. Graphite Transportation, Packaging, and Storage
Graphite is a bulk industrial raw material, so transportation and handling can influence the overall delivered cost and material condition.
Graphite Packaging Options
Common packaging formats include:
- 25 kg bags
- 500 kg bags
- 1,000 kg jumbo bags
- Customized industrial packaging
For large refractory plants, jumbo bags can simplify bulk handling. Smaller packages may be more appropriate for specialty grades or smaller-volume applications.
Packaging should protect graphite from:
- Moisture
- Contamination
- Damage
- Mixing with other grades
Packages should also clearly identify:
- Product name
- Grade
- Batch number
- Net weight
- Supplier
- Manufacturing or packing information where required
Graphite Storage
Good storage practices generally include:
- Keeping bags sealed
- Protecting material from rain
- Minimizing humidity exposure
- Keeping graphite away from contaminants
- Separating different grades
- Maintaining batch identification
- Following appropriate inventory controls
Good storage is part of quality management. Material that meets specifications at dispatch can still become contaminated or mixed if it is improperly handled after delivery.
16. How to Qualify a Natural Graphite Supplier
A structured supplier-qualification process can reduce technical and commercial risk.
Stage 1: Supplier Information
Collect:
- Company profile
- Product catalogue
- Technical datasheets
- Production capacity
- Quality certifications
- Customer references where appropriate
- Supply locations
Stage 2: Technical Evaluation
Review:
- Fixed carbon
- Ash
- Moisture
- Volatile matter
- Particle size
- Flake morphology
- Impurity limits
Stage 3: Sample Testing
Test representative supplier samples against the existing approved material.
Stage 4: Production Trial
Run the graphite through the intended refractory formulation and evaluate the relevant process and product characteristics.
Stage 5: Commercial Evaluation
Compare:
- Material price
- Freight
- Packaging
- Payment terms
- Lead time
- Minimum order quantity
Stage 6: Supplier Approval
Add the supplier to the approved-vendor list if the technical and commercial requirements are satisfied.
Stage 7: Ongoing Monitoring
Continue monitoring incoming batches after approval.
This is more robust than changing suppliers solely because another quotation is cheaper.
17. Questions to Ask a Natural Graphite Supplier
A steel plant or refractory manufacturer can use the following questions during supplier evaluation:
- Is the material natural flake graphite?
- What is the minimum guaranteed fixed carbon?
- What is the maximum ash?
- What is the moisture limit?
- What is the volatile-matter limit?
- Can you provide a complete chemical analysis?
- What is the Fe₂O₃ level?
- What is the SiO₂ level?
- What is the CaO level?
- What is the particle-size distribution?
- What is the flake-size distribution?
- What test methods are used?
- Is a COA supplied with every batch?
- Are COA values typical or guaranteed?
- What is your monthly supply capacity?
- What is your normal lead time?
- What packaging options are available?
- Can you maintain the same specification throughout the year?
- Can you provide samples for plant trials?
- How do you handle rejected or off-specification batches?
The supplier’s answers can reveal more about long-term suitability than the quoted price alone.
18. What Makes a Natural Graphite Supplier Suitable for Large Steel Plants?
A supplier serving a large steel-industry customer needs more than a suitable product.
The relationship often requires:
Technical capability + quality control + supply reliability + documentation + logistics.
A suitable supplier should ideally have defined controls covering:
- Raw-material sourcing
- Processing
- Particle-size control
- Chemical testing
- Batch identification
- Packaging
- Storage
- Dispatch
- Customer complaints
- Corrective action
This becomes increasingly important as order volumes increase.
A small variation in one bag may not be significant.
Repeated variation across hundreds of tonnes can become a manufacturing concern.
19. What Role Does Technical Support Play?
A graphite supplier should understand the general requirements of the application in which its material is being used.
A technically capable supplier can discuss:
- Refractory-grade requirements
- Fixed-carbon targets
- Particle-size requirements
- Flake morphology
- Ash chemistry
- Sampling
- Testing
- Storage
- Application-specific requirements
This does not mean the supplier should formulate the customer’s refractory product.
Rather, the supplier should understand enough about the application to provide the required raw material consistently and communicate effectively with procurement, quality, and production teams.
For steelmaking customers, this technical understanding can improve communication between the supplier and the customer’s technical teams.
20. Why Documentation Matters for Steel-Industry Customers
Industrial procurement involves traceability.
If a problem occurs in a refractory batch, the manufacturer may need to determine:
Which graphite was used?
Then:
Which supplier batch was involved?
Then:
What were the test results for that batch?
Good documentation makes this investigation possible.
Useful records include:
- Purchase order
- Supplier COA
- Batch number
- Incoming inspection report
- Laboratory test results
- Production batch record
- Refractory test results
- Supplier corrective-action records
Traceability allows a quality issue to be investigated systematically rather than treated as an isolated event.
21. Total Cost of Graphite Supply: Why Price Alone Is Not Enough
A lower purchase price can look attractive on a procurement spreadsheet.
However, graphite is a functional raw material. If an inconsistent material affects refractory production, the resulting costs may include:
- Rejected batches
- Production delays
- Additional testing
- Rework
- Higher scrap
- Inventory replacement
- Reduced refractory performance
- Additional maintenance
- Customer complaints
The meaningful comparison is therefore not simply
Supplier A = ₹X/tonne
versus:
Supplier B = ₹Y/tonne
A more useful calculation considers:
Material price + freight + handling + packaging + storage + quality risk = total delivered and usable cost
The lowest quoted price does not necessarily represent the lowest overall procurement cost.
22. Natural Graphite Supplier Checklist for Steel Plants
Before approving a supplier, procurement and technical teams can evaluate the following:
| Area | What to Check |
|---|---|
| Product | Natural flake/natural graphite type |
| Carbon | Minimum fixed carbon |
| Ash | Maximum and chemistry |
| Moisture | Maximum limit |
| Volatile matter | Maximum limit |
| Particle size | Controlled distribution |
| Flake size | Consistent morphology |
| Testing | Defined laboratory methods |
| COA | Available for each batch |
| Consistency | Historical batch data |
| Capacity | Ability to meet annual demand |
| Logistics | Reliable delivery |
| Packaging | Suitable for storage and handling |
| Traceability | Batch identification |
| Trial | Plant qualification available |
| Technical support | Application understanding |
| Commercials | Delivered cost |
| Quality response | Corrective-action process |
This checklist can be used as a starting point for supplier prequalification and should be adapted to the customer’s own quality-management system.
23. Graphite Specification for Steelmaking Refractory Applications
A practical specification might be structured around the customer’s actual formulation.
Product
Natural Flake Graphite – Refractory Grade
Chemical Requirements
| Parameter | Requirement |
|---|---|
| Fixed Carbon | Minimum agreed value |
| Ash | Maximum agreed value |
| Moisture | Maximum agreed value |
| Volatile Matter | Maximum agreed value |
| Fe₂O₃ | Maximum agreed value |
| SiO₂ | Maximum agreed value |
| CaO | Maximum agreed value |
| Other impurities | Application-specific |
Physical Requirements
| Parameter | Requirement |
|---|---|
| Particle Size | Agreed mesh/micron distribution |
| Flake Size | Agreed distribution |
| Appearance | Clean, free-flowing graphite |
| Packaging | Agreed on industrial packaging |
Documentation
- Certificate of Analysis
- Batch number
- Packing details
- Test results
- Product technical datasheet
The numerical values should be determined from the customer’s actual refractory formulation, process requirements, and applicable standards. Buyers should verify the current applicable Indian Standards through the Bureau of Indian Standards rather than relying on outdated generic specifications.
24. How to Monitor Graphite Supplier Quality Over Time
Supplier approval should not be a one-time exercise.
A plant can maintain a supplier quality scorecard using measurable data.
Possible indicators include:
- Percentage of batches accepted
- Number of off-specification deliveries
- Fixed-carbon variation
- Ash variation
- Particle-size variation
- Delivery performance
- Documentation accuracy
- Complaint response time
- Corrective-action effectiveness
This allows procurement and quality teams to identify trends.
For example, if graphite ash gradually increases over several months, the supplier can be contacted before the variation becomes a significant production issue.
25. What to Do When a Graphite Batch Is Off-Specification
The response should ideally be defined before a problem occurs.
A purchase specification can establish:
- Acceptance limits
- Sampling procedure
- Retesting procedure
- Rejection criteria
- Replacement procedure
- Credit procedure
- Corrective-action requirements
For a minor deviation, the technical department may determine that the material can still be used.
For a major deviation, the batch may need to be rejected or segregated.
The important principle is to make the process objective, documented, and agreed upon in advance.
26. Why Long-Term Natural Graphite Supplier Relationships Matter
Steelmaking and refractory production require dependable raw materials.
Once a graphite grade has been technically qualified, changing suppliers may require:
- New samples
- Laboratory analysis
- Trial production
- Requalification
- Inventory changes
- Process adjustments
A stable supplier relationship can therefore reduce unnecessary qualification work.
However, a long-term relationship should still include ongoing quality monitoring.
Approved supplier does not mean permanently exempt from testing.
It means the supplier has demonstrated the ability to meet the agreed requirements.
27. How to Choose a Natural Graphite Supplier for Steel Plants
Choosing a natural graphite supplier for steel plants ultimately requires balancing several factors.
Quality
Does the graphite meet the required technical specification?
Consistency
Does the material remain within specification from batch to batch?
Capacity
Can the supplier support the required volume?
Testing
Are results supported by reliable testing and documentation?
Logistics
Can the material reach the plant according to the required schedule?
Technical Support
Can the supplier communicate effectively with procurement, quality, and production teams?
Commercial Value
Is the delivered cost appropriate for the required quality and supply reliability?
The supplier should therefore be evaluated as part of the customer’s industrial supply chain, rather than simply as a source of commodity powder.
Conclusion: What Should Steel Plants Look for in a Natural Graphite Supplier?
Selecting a natural graphite supplier for steel plants should involve much more than comparing price or headline fixed-carbon percentage.
Natural flake graphite can play an important role in carbon-containing refractory systems such as MgO-C products used in demanding steelmaking environments. The characteristics of the graphite—including purity, particle-size distribution, morphology, and consistency—can be relevant to processing and refractory performance.
A strong supplier-selection process therefore considers the complete picture:
Specification → Testing → Consistency → Supply Capacity → Documentation → Logistics → Technical Support → Commercial Value
A qualified supplier should be able to provide a clearly defined graphite grade, appropriate testing documentation, controlled particle-size characteristics, traceable batches, suitable packaging, and dependable delivery.
Most importantly, steel-industry buyers should evaluate consistency over time. One successful graphite shipment does not necessarily demonstrate reliable long-term supply. Reviewing multiple batches, conducting appropriate qualification trials, and monitoring incoming material can provide a stronger basis for supplier approval.
For refractory manufacturers and steel-industry procurement teams, the right graphite supplier is ultimately one that can repeatedly deliver material that meets the agreed specification and behaves predictably in the customer’s process.
That predictability is what turns a raw-material purchase into a dependable industrial supply relationship.
Frequently Asked Questions
What type of natural graphite is commonly used in steelmaking refractories?
Natural flake graphite is commonly used as a carbon-containing raw material in MgO-C and other refractory systems. Its characteristics can influence thermal and structural properties within the refractory matrix.
What specifications should steel plants request from a graphite supplier?
Important specifications can include fixed carbon, ash, moisture, volatile matter, particle-size distribution, flake characteristics, and relevant impurity levels. The exact requirements should be based on the customer’s formulation and agreed technical specification.
Why is graphite purity important in MgO-C refractories?
Graphite purity can influence the composition of the refractory raw-material system. Mineral impurities can participate in high-temperature reactions, making chemical analysis important for controlled refractory formulations.
Why does graphite particle size matter in refractory applications?
Particle-size distribution can influence packing, porosity, processing behavior, and other physical characteristics of the refractory. The appropriate distribution depends on the formulation and manufacturing process.
What should a graphite Certificate of Analysis include?
A COA can include fixed carbon, ash, moisture, volatile matter, particle size, relevant impurity analysis, batch number, and test information. Buyers should also distinguish between typical and guaranteed values.
How can a steel plant evaluate graphite supplier consistency?
A buyer can compare multiple batch test results, monitor incoming material against the agreed specification, conduct qualification trials, and maintain a supplier quality scorecard.
How should a new natural graphite supplier be qualified?
A practical process includes technical-document review, sample testing, production trials, commercial evaluation, supplier approval, and ongoing monitoring of subsequent batches.