Rotating rabble arms move ore across stacked hearths in a multiple-hearth furnace. Explore the arrangement and calculate feed and sulfur masses from entered feed rate, composition, removal fraction and run time.
Sulfur Mass-Balance Calculator
Enter declared feed rate, sulfur mass fraction, sulfur-removal fraction and run time. The calculator balances the entered sulfur masses and reports a maximum sulfur-dioxide equivalent if every removed sulfur atom is represented as SO2; it does not predict furnace conversion or emissions.
Equation Used
- Feed rate, run time, sulfur mass fraction and removed fraction are entered assumptions for the mass calculation.
- All quantities use metric tonnes consistently; multiplying a mass by a mass fraction preserves the mass unit.
- The maximum SO2 equivalent assigns one mole of SO2 to each mole of removed sulfur and uses molecular mass 64.064 and declared sulfur atomic mass 32.06.
- Ore mineralogy, reactions, oxygen demand, gas composition, temperature, residence time, heat balance, fuel, fluidization, capture, equipment sizing, emissions compliance and safety are excluded.
Stacked hearths and rotating rabbles illustrate the ore path. The numerical results use the entered sulfur fractions; they do not calculate conversion from furnace conditions.
Rotating rabbles move ore across alternating hearths
US Patent 4,437,884 describes a Nichols-Herreshoff furnace with vertically stacked hearths around a rotating hollow central shaft. Rabble arms project from the shaft, and vane-like rabbles mix and turn the ore while directing it radially.
Material moves toward the center on one hearth, falls through its axial opening, then moves outward on the next hearth and falls near the perimeter. Repeating this alternating path carries material from the upper feed to the lower discharge while gases circulate through the furnace.
Multiple-hearth roasting principle
The patent applies the illustrated furnace to oxidative roasting of metal-sulfide ores and concentrates. This page does not select a roaster, specify a mineral reaction, validate a plant flowsheet or provide operating guidance.
Real high-temperature sulfur-bearing processes require site-specific mineralogy, test work, mass and energy balances, gas treatment, controls, qualified engineering and applicable environmental and safety requirements.
Sulfur mass relationships
NIST lists SO2 molecular mass as 64.064. The displayed SO2 value is the maximum mass equivalent if each removed sulfur atom is represented in SO2; it is not a stack-flow or emissions prediction.
Sulfur mass example
For F=125 t/h, h=24 h, S=30 mass % and X=80%, declared feed mass is 3,000.0 t, sulfur in the feed is 900.00 t, declared sulfur removed is 720.00 t, declared sulfur retained is 180.00 t and the maximum SO2 equivalent is about 1,438.74 t.
No temperature, oxygen, fuel, residence-time or equipment claim follows from this arithmetic.
Furnace motion and mass-calculation limits
The animation is a phase diagram of a central shaft, radial rabble arms and alternating drop paths. It does not reproduce a particular furnace's dimensions, tooth angles, speeds, temperatures or material residence time.
A mass calculation alone does not determine reaction rate, heat demand or operating conditions. Those depend on ore chemistry, gas contact, heat transfer and the actual equipment. The moving markers are illustrative rather than a residence-time simulation.
Ore-roasting-furnace questions
Does the calculator predict autogenous operation?
No.
Is maximum SO2 equivalent a stack-emission estimate?
No. It is a stoichiometric mass ceiling under the declared one-S-to-one-SO2 representation.
Does the entered sulfur-removed percentage come from the furnace animation?
No. It is an entered assumption for the mass calculation.
Does this select a multiple-hearth, fluid-bed or rotary roaster?
No.
Is this process-control or safety guidance?
No.
Ore-roasting-furnace references
- US Patent 4,437,884, Ore roasting with recycle of gases: primary patent description of the Nichols-Herreshoff stacked hearths, rotating shaft, rabble arms, alternating inward/outward ore path and counter-flowing gases.
- US Patent 1,068,955, Rabble-arm for roasting-furnaces: primary patent description of a rotating shaft, cooled rabble arm, removable rabble-carrying bar and blades.
- NIST Chemistry WebBook, sulfur dioxide: formula SO2 and molecular weight 64.064.
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