In the field of tin metal smelting, electric arc resistance furnace is becoming the preferred equipment for
processing complex tin concentrates by virtue of its unique thermal mechanism and metallurgical efficiency.
In this paper, we will analyze the process principle of electric arc furnace, technological innovation and
the key role in tin smelting, to provide professional technical reference for the industry.
Electric arc resistance furnace: tin smelting of the “energy heart”
Arc resistance furnace is a set of arc heating and resistance heating dual mechanism in one of the special
metallurgical equipment, designed to handle tin concentrate containing 30-70% tin. Its core value lies in
the direct conversion of electric energy into metallurgical heat energy, realizing the efficient reduction of
tin oxides, increasing the smelting recovery rate to over 95%, and saving 30-40% energy compared with
the traditional reflector furnace.
The equipment adopts the “three-zone synergistic” working mechanism:
Arc excitation zone: 2000-3000℃ high temperature arc is formed between electrode and slag.
Resistance heating layer: Joule heat is generated by the current through the solid charge.
Melting pool reaction zone: complete the reduction reaction of SnO₂→Sn.
Three-zone linkage makes the thermal efficiency reach 65-75%, far more than conventional melting equipment.
Technological breakthrough: four core innovations analyzed
1. Composite heating system
Adopting liftable graphite electrode (diameter 400-800mm), realized by intelligently adjusting the electrode
insertion depth (10-30cm):
Arc mode: dealing with cold material start-up phase
Resistance Mode: Maintaining the molten pool temperature
Hybrid mode: handling high impedance charge
This design reduces the energy consumption of tons of tin to 2800-3200kWh, 35% lower than the traditional process.
2. Dynamic slag layer control
Development of real-time slag resistance monitoring system (accuracy ±0.5mΩ):
Slag layer thickness: maintain 40-60cm
FeO/SiO₂ ratio: control in 1.2-1.5
Alkalinity regulation: CaO/SiO₂=0.6-0.8
Through precise regulation, the tin direct yield is increased to 92%, and the slag content of tin is reduced to below 0.8%.
3. Multi-phase flow field optimization
Furnace body adopts 30° inclined design, together with multi-hole air blower at the bottom:
Gas rising speed: 0.8-1.2m/s
Melt circulation volume: 8-12 times/hour
Bubble diameter: 5-8mm
Reinforce the mass transfer efficiency and shorten the reduction reaction time to 2-3 hours.
4. Intelligent control system
Integrate four major function modules:
Power regulation: dynamic matching electrode voltage (200-400V)
Temperature field analysis: 16-point infrared temperature measurement (accuracy ±5℃)
Component monitoring: online laser spectrum detection
Safety protection: leakage warning and automatic power-off
Realization of the whole process of digital control, operators reduced by 50%.
Typical application scenarios and process data
1. Low-grade tin ore treatment
Raw material: Sn 25-40%, Fe 15-25%, As 3-8%
Process parameters:
Melting temperature: 1250-1350°C
Ratio of reducing agent: anthracite 6-8%
Melting agent composition: quartzite 12-15%, limestone 5-8%
Output index:
Crude tin grade: ≥99
Slag tin content: ≤ 0.9%
Arsenic solidification rate: ≥98
2. Comprehensive smelting of polymetallic ores
Treatment of complex ores containing Sn, Cu, Zn, In:
The use of “stepped reduction” process:
1250 ° C priority reduction SnO₂
1350 ℃ recovery of copper alloy
Soot enrichment of In, Zn oxides
Comprehensive metal recovery:
Sn 94%, Cu 88%, In 75%, Zn 82%.
3. Smelting slag regeneration
For the waste slag containing 2-5% Sn:
Equipped with special electromagnetic stirring device
Add sulfurizing agent for matting treatment
After secondary recovery, the residual slag contains Sn≤0.3%.
Realize the resource utilization of waste.
Equipment selection of the five golden rules
1. Power configuration calculation
Suggested formula: P = K × Q × (Tm + ΔT) / η
K: material coefficient (tin concentrate take 0.35)
Q: processing capacity (t/h)
Tm: target temperature (℃)
ΔT: heat loss compensation
η: thermal efficiency (take 0.65-0.7)
2. Furnace structure selection
Round furnace: suitable for small and medium scale (≤5000t/a)
Rectangular furnace: suitable for continuous production (≥8000t/a)
Composite furnace: processing multi-metal complex ore
3. Environmental protection supporting programs
Necessary system:
High-temperature bag de-dusting (emission ≤20mg/m³)
Two-stage alkaline desulfurization (efficiency ≥95%)
Arsenic curing treatment device
Waste heat power generation system (recovery rate ≥30%)
4. Refractory material system
Recommended configuration:
Slag line zone: magnesium-chromium brick (thickness 400mm)
Melting pool area: high alumina silicon carbide brick
Furnace top: corundum castable
Service life: 18-24 months
5. Intelligent upgrade
Suggested option:
Digital twin control system
Electrode automatic adjustment device
Material Intelligent Dosing System
Remote fault diagnosis module
Future technology evolution direction
1. Plasma strengthening technology
Research and develop plasma-arc composite generator:
Increase energy density to 5kW/cm³.
Reduce electrode consumption by 30%.
Processing ultra-poor ores containing <20% tin
2. Hydrogen-based clean smelting
Develop hydrogen alternative carbon reductant process:
Hydrogen injection rate: 20-30m³/t
Reduction efficiency increased to 98
Reduce CO₂ emission by 80%.
3. Multi-metal synergistic extraction
Integrated electrolysis, vacuum distillation module:
Tin-lead separation factor ≥1000
Indium recovery rate increased to 85
Gold and silver enrichment ratio of 50:1
Driven by the “Double Carbon” strategy, electric arc furnace technology is developing rapidly in
the direction of high efficiency, cleanliness and intelligence. Its unique thermal mechanism not
only improves the economic efficiency of tin smelting, but also opens up a new path for the
comprehensive recovery of complex multi-metal resources. With the continuous breakthrough
of core technology, this process will certainly play a more important role in the field of strategic
metal resource security, and promote the entire non-ferrous metal industry to the green and
low-carbon direction of transformation and upgrading.