Castings: Cupola Furnace Troubleshooting and Techniques

The Cupola Furnace Troubleshooting and Techniques course is an informative advance-level course for cupola operators working firsthand with a cupola furnace. The course provides operators with an introduction to the most common troubleshooting situations and practical techniques to employ when problems occur. It also focuses on the ramifications of cupola design, the benefits of operating an optimally designed cupola, as well as how to make desired changes to carbon content, spout temperature, and melt rate.

Learning Objectives

  • Understand what is the optimum blast air rate and how it affects the efficiency of a cupola.
  • Recognize the correct immediate checks per troubleshooting situation.
  • Identify the correct corrective actions per troubleshooting situation.
  • Distinguish between the different utilization capacities of a cupola.
  • Comprehend the methodology of changing the state of a cupola.
Course Length: 3 HRS

Table of Contents

Cupola Furnace Troubleshooting and Techniques Overview

Cupola Design

  • What Is an Efficient Cupola Design?
  • Operating at the Optimum Blast Air Rate
    • Blast Air Rate per Unit Area
    • Average Tuyere Velocity
  • Oversized or Undersized Cupolas for Melt Demand
  • Stack Gas Concentrations

Changing the Cupola State

  • Melt Rate Control
  • Carbon Control
    • Suggestions for Lowering Carbon
    • Suggestions for Increasing Carbon


  • Out-of-Control Temperatures
    • Immediate Checks
    • Corrective Action: Blast Air Rate/Pressure Change
    • Corrective Action: Temperature Reading Inaccurate
    • Corrective Action: Blast Air System Leaks
    • Corrective Action: Tuyere Leaks
    • Corrective Action: Charge Change/Heavy Metallics
    • Corrective Action: Cupola Full
    • Corrective Action: Uneven Charge Distribution
    • Corrective Action: Wet Coke
    • Corrective Action: Coke Size Change
    • Corrective Action: Tap Hole Obstruction
    • Corrective Action: Viscous Slag
    • Corrective Action: Bridging or Scaffolding
    • Corrective Action: High Humidity
    • Determine Approximate Coke Bed Height
    • Long-Term Action
    • Specific Situation: Cold Iron after an Unscheduled Shutdown
  • Chill Test Changes
    • Chill Too High: Hard Iron
    • Chill Too Low: Soft Iron
  • Cupola Bridging
    • Immediate Checks
    • Corrective Action
    • Further Checks
    • Further Action: Oversized Charge Metallics
    • Further Action: Insufficient Flux
    • Further Action: Uneven Charge Distribution
    • Further Action: Charging System Working Improperly
    • Further Action: Poor Refractory Lining
    • Further Action: Improper Refractory Installation
    • Further Action: Front Slagging Iron Dam Too High
    • Further Action: Rear Slagging Slag Hole Too High
    • Further Action: Poor/Weak Coke
    • Further Action: Excessive Blast Air Rate
    • Further Action: Too Many Shutdowns
    • Further Action: Leaking Tuyeres
    • No Blast Air Reduction at End
    • Potential Situation: Frozen Cupola
  • Excessive Windbox Pressure
    • Common Excessive Windbox Pressure Indications
    • Further Checks
    • Further Action: Bridging
    • Further Action: Tuyere Velocity Too High
    • Further Action: Slag Buildup on Tuyere ID
    • Further Action: Dirt/Sand in Charge
    • Further Action: Small Coke/Excessive Fines
    • Further Action: Tuyeres Too Small for Blast Rate
    • Further Action: Mismatched Blower/Exhaust System
  • Excessive Refractory Consumption
    • How to Determine Excessive Refractory Consumption
    • Further Checks
    • Further Action: Bridging
    • Further Action: Poor Refractory Material
    • Further Action: Poor Refractory Removal
    • Further Action: Uneven Charge Distribution
    • Further Action: Excessive Flux Use
    • Further Action: Unequal Blast Air Distribution
    • Further Action: Under Blown
    • Further Action: Water Leaks
    • Further Action: Large Charge Materials
    • Further Action: Incompatible Refractory/Slag
    • Further Action: Incorrect Cupola Design
    • Further Action: Inconsistent Charge Weights
    • Further Action: Dark Tuyeres

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