Iron Ore Pelletizing technical illustration · conceptual illustration
Define the comparison
A fair comparison starts with a common design basis. Ask each proposal to identify the feed envelope, product requirements, annual availability assumptions and scope boundaries. A technology name alone cannot establish the best choice for a particular project.
Make exclusions visible
Compile a responsibility matrix covering civil works, utilities, emissions-control interfaces, automation, commissioning and training. Record exclusions next to the quoted scope. Where one proposal includes a service and another does not, obtain a comparable scope before evaluating commercial terms.
Ask for evidence with a boundary
Request references that explain the ore, product, equipment configuration and period over which performance was demonstrated. Treat supplier forecasts, model outputs and operating records as different types of evidence. Do not convert a percentage improvement from one reference plant into a guaranteed result for another.
Review the operating life
Bring operations and maintenance teams into the review while changes are still practical. Walk through inspection access, replacement procedures, lifting requirements, critical spares and shutdown activities. A drawing review should ask how work will actually be performed, not only whether equipment fits inside the building.
Agree how acceptance will work
Define the testing period, permitted feed variability, sampling responsibilities and treatment of interruptions. Identify the contractual response if the trial cannot be completed under the specified conditions. These decisions belong in the project process before commissioning, when all parties can still plan around them.
Map the thermal route and its interfaces
A straight-grate route carries the bed through successive treatment zones on a travelling grate. A grate-kiln route uses a travelling grate for initial treatment, a rotary kiln for firing and a cooler. The arrangement affects transfers, mechanical scope and heat-recovery connections. Neither label alone establishes energy consumption, ore suitability or lifecycle cost.
Compare the complete proposed arrangement on a common material basis, including the preparation and classification required to deliver the specified green feed. The equipment boundary must state which fans, ducts, heat-recovery connections, combustion controls and emissions interfaces are included. A quotation that excludes these is not directly comparable to a complete thermal-system price.
Normalise the energy comparison
| Quantity | Required basis | Common comparison error |
|---|---|---|
| Fuel | Energy input, fuel heating-value basis and reporting period | Comparing fuel volume without composition or calorific value. |
| Electricity | Included drives and auxiliaries per accepted dry tonne | Omitting fans or comparing gross tonnes with saleable tonnes. |
| Production | Dry product meeting the agreed specification | Including off-specification or inventory drawdown as output. |
| Availability | Calendar hours, planned outages and unplanned downtime | Using an equipment availability claim as annual plant utilisation. |
Illustrative denominator check
A period consuming 90,000 GJ while producing 100,000 t accepted dry pellets has a specific input of 0.90 GJ/t. If only 95,000 t meets the agreed product specification, the same energy input becomes 0.947 GJ per accepted tonne. No furnace deterioration is required for this indicator to rise.
This calculation does not include electrical energy or upstream/downstream operations. Establish the boundary first, then add the relevant streams consistently. Do not add fuel and electricity without explaining conversion and whether the objective is site energy, purchased cost or emissions.
Test a performance guarantee against realistic variability
Specify which feed ranges apply during the acceptance test and how they will be verified. The owner needs to understand whether the guarantee covers a narrow reference blend or the intended commercial feed programme. Ask how a change in mineralogy, moisture or size distribution is treated and who approves any correction formula.
Acceptance should identify the measurement instruments, calibration evidence, sampling frequency, laboratory responsibilities and handling of interruptions. If the equipment is tested before upstream feed is stable, a failed run may not isolate equipment performance. If the test ignores normal variation, a passed run may not represent routine production. Both outcomes are avoidable with a defined protocol.
Evaluate maintainability with a planned replacement exercise
Choose a critical component and trace its removal from the operating position to the maintenance area. Verify isolation, lifting routes, access, clearance and the availability of handling equipment. Identify which adjacent equipment must stop or be removed. Include consumables, labour and restart activities in the outage estimate.
Translate the exercise into an annual risk picture. Long delivery times, single-source items, limited crane access or missing spare assemblies can dominate downtime even when the component purchase price is modest. Ask for a critical-spares strategy tied to the proposed configuration and the owner’s maintenance capability.
Technical references
Metso — Basics in Minerals Processing handbook ↗
ISIJ International — oxygen level, oxidation and magnetite pellet-bed induration (2021) ↗
References support the underlying principles. Diagnostic sequences, worked examples and procurement questions are original engineering analysis; they are not plant operating instructions or verified supplier performance results.