Metalcess has long specialized in non-ferrous metallurgical engineering and equipment, providing integrated solutions for tin mines—ranging from tin cassiterite pretreatment, tin concentrate smelting, smelting slag and hard-head treatment, crude tin refining, high-purity tin production, to flue gas treatment, electrical and automation control.

Based on the tin ore chemical composition and phases, iron concentration, and high-melting-point metals, Metalcess designs tailored EAF furnace reduction smelting, hard-head TSL furnace fuming, and subsequent refining processes to maximize the recovery of valuable metals while minimizing the loss of impurities into crude tin and smelting slag. This ensures that tin resources and associated valuable resources are fully utilized.

1. Electrical Arc Furnace Tin Reduction Smelting

The reduction smelting of tin concentrate is a critical step in producing crude tin. Metalcess offers “alternating current electric arc furnaces (AC EAF) and direct current electric arc furnaces (DC EAF)” for tin concentrate smelting. Compared to traditional fuel-fired furnaces, arc furnaces offer the following advantages:

Ø  High-temperature capability;

Ø  Flexible adjustment of furnace temperature and power;

Ø  Easy control of the reducing atmosphere;

Ø  Adaptability to complex tin concentrates;

Ø  Ease of automating the smelting process;

Ø  A relatively compact process flow;

Ø  Ease of optimizing smelting parameters for different ores.

Recovery pathways for associated metals are considered during the tin smelting stage to ensure full recovery of valuable associated metals. Metalcess can perform “parametric” design of the electric furnace (including furnace power, electrode configuration, furnace chamber dimensions, charge composition, reducing agent dosage, slag type, smelting temperature, smelting time, melt pool depth, and tin tapping and slag discharge schedules) based on the content and occurrence of high-temperature metals in the raw materials, as well as the target products.

High-melting-point metals in tin ores presents different distribution behaviors during smelting. By appropriately controlling smelting conditions, the distribution of high-temperature metals in the metal phase, slag phase, and subsequent products can be managed, thereby creating conditions for the further recovery of associated metals. By optimizing electric arc furnace smelting parameters and the slag system, the distribution of valuable elements can be controlled for different ores, and recovery processes can be further designed for smelting slag containing valuable metals.

From the perspective of the entire resource value chain, a holistic design is implemented for the sequence: tin→associated valuable metals→smelting slag→flue dust→refining by-products. The ultimate goal is to minimize resource loss as much as possible and achieve full recovery of valuable resources.

2. Iron-Bearing Tin Slag Fuming Treatment

During the smelting process of high-iron tin ore, “hardhead”—a byproduct with high iron and low tin content—will be formed as smelting slag.

Metalcess has developed a flexible TSL furnace fumigation solution for treating hardhead. The TSL fumigation technology allows tin to enter the flue gas, enabling further recovery and reducing the tin content in the hardhead to below 0.5%.

Why use a TSL furnace for hardhead fumigation? Compared to traditional large-scale fumigation furnaces, the TSL furnace offers greater production flexibility.

Traditional fumigation furnaces for tin slag and tin hardheads typically have large processing capacities and require continuous operation. These furnaces heat up slowly during cold starts, and it takes a long time to establish thermal equilibrium inside the furnace. To ensure continuous production, external support systems—such as high-temperature slag transfer systems, slag electric furnaces, and other continuous feeding and heat-preservation facilities—are typically required. This makes the overall system investment and operational organization highly complex. More importantly, the melt pool line and skimming zone in traditional fumigation furnaces are largely fixed, limiting adjustments to furnace capacity and operating parameters for each batch.

The TSL furnace uses a vertically movable refining lance for melt agitation and blowing, eliminating the fixed slag line found in traditional fumigation furnaces.

Consequently, the following parameters can be flexibly adjusted based on the actual volume of hard-head produced:

Ø  Single-batch processing capacity;

Ø  Blowing time;

Ø  Blowing intensity;

Ø  Refining lance insertion depth;

Ø  Air/oxygen supply;

Ø  Furnace temperature and operating parameters.

The TSL furnace can be started and shutdown on demand, making it particularly suitable for processing tin hard heads generated intermittently at tin smelting plants. Metalcess can provide small TSL furnaces based on hard head production volumes, with a minimum inner diameter of approximately φ600 mm, enabling compact smelting treatment.

3. Pyrometallurgical Refining of Crude Tin

The product of electric arc furnace smelting is typically crude tin, which contains impurities such as iron, arsenic, lead, bismuth, and copper, and requires further refining to produce high-purity tin.

Metalcess has extensive experience in pyrometallurgical refining and can design different refining processes based on the composition of the crude tin and the requirements of the final product.

Common refining sequences include: crude tin → iron/arsenic removal → spiral crystallization for lead and bismuth removal → high-purity tin.

4. 4N–5N High-Purity Tin

For customers requiring high-quality tin products, Metalcess combines spiral crystallizer with a vacuum distillation furnace.

Spiral crystallization utilizes the solidification and segregation characteristics of different metals in tin to separate impurities such as lead and bismuth from the tin. At the same time, lead- and tin-containing byproducts generated during the refining of crude tin can be further processed in the vacuum distillation system.

Through multi-stage vacuum distillation, tin and lead can be further separated, reducing tin loss in lead vapor and yielding corresponding tin and lead products. Metalcess’s current technical process already employs vacuum distillation to treat lead-containing tin by-products.

To meet higher product quality requirements, Metalcess can further produce 4N–5N high-purity tin through process integration and optimization of refining parameters. Tin smelters can obtain higher-quality products through further processing, thereby securing a higher premium for product quality.

5. Intelligent Tin Smelting Plant Management

Metalcess not only provides the smelting furnaces but also integrates the entire tin smelting production system into a unified automated management framework.

Through the SCADA system, unified management is achieved from raw material preparation and smelting to flue gas treatment. Raw Material Preparation → Batching → Weighing → Conveying → Electric Furnace Smelting → Tin Discharge/Slag Disposal → Hard Head Treatment → Flue Gas Treatment

Operators can monitor the following in real time:

Ø  Raw material conveying status;

Ø  Batching and weighing data;

Ø  Electric furnace operating parameters;

Ø  Current, voltage, and power;

Ø  Smelting status;

Ø  Furnace temperature;

Ø  Fume treatment system operating status;

Ø  Fan and dust collection equipment operating status;

Ø  Alarm and interlock statuses of key equipment.

At the same time, the SCADA system can collect, monitor, and manage data in real time based on actual smelting conditions, enabling closer coordination between raw material preparation, smelting, and environmental protection systems.