Dc Furnace For Tin Slag Smelting And Recovery (New)

Dc Furnace for Tin Slag Smelting and Recovery

  Electric furnace melting in non-ferrous metal smelting is to melt the material by electric energy through the arc generated by the electrode and the charge or the high temperature generated by the resistance of the molten slag. And can control the melt temperature in the range of 1200 ~ 1600℃ any temperature. Smelting furnace is mainly used for smelting materials containing a large number of refractory gangue components, and in areas with sufficient power resources, it is also used for smelting general ore.
  The main advantages of EAF melting are: the bath temperature is easy to adjust and can reach a higher temperature; Low theoretical smoke volume; High thermal efficiency, up to 60% ~ 80%; The amount of slag is small, and the total recovery rate of melted metal is high.
  The main disadvantages of electric furnace smelting are: large power consumption, high processing cost and higher than that of reverberatory furnace smelting; The water content of the charge generally does not exceed 3%; Infrastructure investment is slightly higher.
  Electric furnace is used in the smelting of copper, nickel, zinc, tin, etc. as well as the heat preservation and dilution of molten slag.

Application of tin smelting furnace:
  Tin concentrate smelting electric furnace is suitable for smelting low tin concentrate to reduce tin, smelting back slag, smelting rich slag containing silicon into silicon tin.
  The electric furnace uses the arc generated by the electrode and the charge and the direct use of molten slag as resistance and strong current method to convert the electric energy into the heat energy required by the smelting process, and it is easy to reach a high furnace temperature (1450 ~ 1600℃). As a result, refractory concentrates can be successfully treated without the need for large amounts of flux in EAF smelting.
  The electric furnace is basically sealed, and a high concentration of carbon monoxide can be maintained in the furnace, so the charge with a higher melting point can be melted, and the slag with low tin content can be obtained. Therefore, electric furnaces are generally suitable for processing tin concentrates with low iron content.
  In electric furnace smelting, the furnace gas is basically the carbon monoxide and carbon dioxide produced by the reduction reaction, and its amount is much less than that of the reverberatory furnace. (Most of the furnace gas is fuel combustion flue gas), therefore, the amount of tin and its compounds volatilized to the furnace gas is less, and the dust collection equipment used is also smaller.
  The production rate of electric furnace smelting is very high, and the poor tin slag can be obtained after one smelting in electric furnace.
  The disadvantage of electric furnace melting is that it is difficult to adjust the composition of slag and gas. At high temperature, the volatilization loss of tin compounds increases sharply. In addition, the electricity consumption is relatively large, and the investment of electric furnaces and their auxiliary equipment is much larger than that of reverberatory furnaces. At present, it is more suitable for use in areas where electricity is convenient, or when the concentrate contains high refractory components and low iron content.

Core Working Principle

• Basic Structure: Composed of a cylindrical steel shell, refractory lining, central graphite electrode (cathode), and hearth-embedded anode.
• Heating Method: The DC arc generates a high temperature of 1400-1600°C to melt tin slag, and the molten tin and slag are separated by gravity due to density differences.
• Key Process: Add quartz stone, lime, etc. to adjust the slag type, control the viscosity and melting point of the slag, and promote the separation of tin and slag, then recover the crude tin through tapping holes.

Core Advantages

New Design and Application Cases

1. 1250 kVA Circular DC Furnace: A smelting company uses this furnace to process 133 tons of high and low aluminum slag and 400 tons of flue dust per month, with an average tin grade of 45% in the furnace, producing 240 tons of crude tin per month and saving 1.1 million yuan in production costs annually compared with the original process.
2. DC Plasma Melting Furnace: The smelting chamber is divided into two molten pools by a weir, and each pool has a plasma zone, which improves the efficiency of tin recovery and the quality of crude tin.
3. Large-Scale DC Furnace (30 MW): It has a compact structure, simple roof design, and good gas tightness, which can reduce air intake and improve the quality of flue gas, and is suitable for large-scale tin slag treatment plants.

Key Process Parameters

• Power: 1000-3000 kVA for small and medium-sized furnaces, and more than 10 MW for large-scale furnaces.
• Temperature: Control the melting temperature at 1400-1600°C to ensure the fluidity of the slag and the separation effect.
• Slag Type Control: Add 10-15% quartz stone and 5-8% lime to adjust the slag type and control the slag viscosity.
• Recovery Index: The direct recovery rate of tin is more than 90%, and the tin content in the final slag is less than 0.3%.

Process Flow

1. Raw Material Preparation: Crush and screen tin slag, mix with quartz stone, lime, etc. in proportion.
2. Feeding: Add the mixed material into the DC furnace through the feeding port.
3. Melting and Separation: The DC arc heats and melts the material, and the molten tin and slag are separated by gravity.
4. Tapping: Tap the crude tin and slag through separate tapping holes respectively.
5. Flue Gas Treatment: Purify and recover the flue gas to reduce environmental pollution.

Development Trend

• Intelligent Control: Adopt automated systems to monitor parameters such as temperature, current, and voltage in real time to optimize the smelting process.
• Environmental Protection and Energy Saving: Combine with flue gas waste heat recovery technology to further reduce energy consumption and emissions.
• Large-Scale and High Power: Develop large-scale DC furnaces above 5-10 MW to meet the needs of large-scale tin smelting enterprises.