Key Takeaways & Executive Findings
- •• • Optimal gas−liquid mixing is achieved at melt viscosities of 0.01 and 0.5 Pa·s, whereas minimal splashing occurs within 0.1−0.25 Pa·s (approximately 1076−1100 °C); this non-overlapping window forces operators to prioritize either mixing or splash suppression, directly affecting reaction completeness and metal recovery. • • Shear stress on the furnace lining increases with melt viscosity and rises particularly rapidly in the 0.1−0.25 Pa·s range, making this interval a critical erosion-risk zone that accelerates refractory wear and shortens campaign life. • • The regions surrounding the oxygen lances are the most susceptible to erosion, identifying localized lance-adjacent refractory as the primary failure point and directing maintenance and design efforts to this area. • • A recommended operating viscosity of 0.01−0.1 Pa·s minimizes erosion while maintaining acceptable mixing, providing a concrete control target for industrial bottom-blowing lead smelting that co-processes lead-containing waste materials.
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Abstract
The co-processing of lead-containing waste materials in oxygen bottom-blowing lead smelting alters melt viscosity, which in turn governs gas−liquid mixing efficiency, splashing behavior, and furnace lining erosion. A multi-fluid volume of fluid (VOF) model, incorporating experimentally determined high-lead slag viscosity values, was applied to an industrial-scale bottom-blowing furnace to resolve these coupled phenomena. The simulations demonstrate that optimal gas−liquid mixing occurs at viscosity values of 0.01 and 0.5 Pa·s, whereas minimal splashing is confined to the viscosity range of 0.1−0.25 Pa·s, corresponding to temperatures of approximately 1076−1100 °C. The regions surrounding the oxygen lances are identified as the most susceptible to erosion. Shear stress increases with melt viscosity, rising particularly rapidly within the 0.1−0.25 Pa·s interval. To minimize erosion, the melt viscosity should be maintained within 0.01−0.1 Pa·s. These findings provide quantitative thresholds for viscosity control in industrial bottom-blowing furnaces processing lead-containing secondary materials, enabling trade-offs between mixing intensity, splashing suppression, and lining protection to be optimized on an operational basis.
1. Introduction
Oxygen-enriched bottom-blown smelting is widely deployed in non-ferrous metallurgy for its high energy efficiency, intense smelting rate, and capacity to process complex low-grade ores. The introduction of lead-containing waste materials, such as slag and dust, into the feed modifies melt composition and raises viscosity, which can cause incomplete reactions, excessive splashing, and accelerated erosion of the furnace lining. Existing experimental studies have established that viscosity governs bubble size, momentum transfer, and flow regime transitions, but these findings have not been translated into quantitative, furnace-scale design thresholds for industrial bottom-blowing vessels.
This work addresses that gap by coupling experimentally determined high-lead slag viscosity values with a multi-fluid volume of fluid (VOF) model of an industrial-scale bottom-blowing furnace. The simulations resolve gas−liquid mixing efficiency, splashing behavior, and wall shear stress across a viscosity range relevant to lead smelting, thereby identifying the operating windows that balance mixing performance against splashing and lining erosion. The resulting viscosity thresholds provide a directly actionable basis for feed blending and thermal control in furnaces that co-process lead-bearing secondary materials.
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Cheng-lin LI, You YAN, Ao HAO, Wei-wen HU, Zi-lin YANG, Dong-ling WU, Liu LIU, Hong-jie YAN (2026). CFD modeling of gas−liquid mixing and splashing in industrial-scale bottom-blowing furnace: Effects of melt viscosity. Transactions of Nonferrous Metals Society of China (中国有色金属学报). https://doi.org/10.1016/S1003-6326(26)67070-7
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Frequently Asked Questions
What is the dominant failure mechanism of the furnace lining under high-viscosity melts, and where does it initiate?
Shear stress exerted by the gas−liquid flow on the refractory increases with melt viscosity, rising particularly rapidly in the 0.1−0.25 Pa·s range. The regions surrounding the oxygen lances experience the highest shear stress and are the most susceptible to erosion, making lance-adjacent refractory the primary failure location.
Can a single viscosity setpoint simultaneously deliver optimal mixing and minimal splashing?
No. Optimal gas−liquid mixing occurs at 0.01 and 0.5 Pa·s, while minimal splashing is observed only within 0.1−0.25 Pa·s (approximately 1076−1100 °C). These windows do not overlap, so operators must select a viscosity that prioritizes either mixing intensity or splash suppression, or accept a compromise outside both optima.
What viscosity range should be targeted to minimize erosion without sacrificing acceptable mixing?
The recommended operating viscosity is 0.01−0.1 Pa·s. This range avoids the rapid shear-stress escalation that occurs between 0.1 and 0.25 Pa·s while retaining mixing performance at the lower bound of 0.01 Pa·s.
How does the multi-fluid VOF model improve on prior experimental viscosity studies for industrial-scale design?
Prior experimental work identified qualitative trends, such as larger bubbles and enhanced momentum transfer with increasing viscosity, but did not provide furnace-scale thresholds. The multi-fluid VOF model integrates experimentally determined slag viscosity values and resolves local shear stress, splashing, and mixing in an industrial-scale bottom-blowing furnace, yielding quantitative operating windows rather than qualitative trends.
What are the operational implications of co-processing lead-containing waste materials on melt viscosity control?
Incorporating slag and dust into the smelting feed modifies material composition and raises melt viscosity, which can push the melt into the 0.1−0.25 Pa·s erosion-critical range. Maintaining viscosity within 0.01−0.1 Pa·s through feed blending and thermal management is therefore necessary to prevent accelerated lining wear while preserving reaction efficiency and metal recovery.
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