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Shaft furnace
Dosing5
Melting 2(1)

STØTEK Shaft Furnace

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The STØTEK shaft furnaces are fully automatic melting- and holding furnaces with hydraulic tilts. The furnaces are divided into two chambers – a melting shaft and a holding part.

STØTEK shaft furnaces are fully automatic charged. This means that a signal from the shaft indicating that there is room for additional metal in the shaft, combined with the holding part not being completely full, activates an automatic charge from the elevator into the shaft.

To maintain an exact metal temperature in the holding part +/-3 C, STØTEK recommends that the holding part always be minimum two-three times larger than the melting capacity. This also provides a better and more homogeneous metal quality.

The STØTEK Shaft Furnace is built as a solid stable steel construction. The furnace consists of a Tilting/Lifting Table, a melting and holding section as well as a charge elevator for the charging of aluminium alloy and the discharge material. The furnace concept is to maximize energy efficiency ensuring the lowest possible CO2 emission and to ensure low operating costs. Thereby, it offers the optimal solution taking the environment as well as the bottom line into consideration.
From a metallurgic point of view, it is an advantage to operate with a good melting and holding process. A fast melting process combined with the most indirect heating as possible increases the quality of the molten aluminium.

The burners are therefore positioned, so that there is no direct flame contact with the melting metal. Furthermore, the burners operate with reduced flame, i.e. they operate with minimal oxygen excess.

The furnace tower consists of special tested materials fulfilling the high mechanical requirements in the shaft. The melting of the metal is performed by two melting burners controlled by a temperature sensor.
The charge elevator automatically charges metal at the top of the shaft. The shaft lid automatically opens/closes by means of a hydraulic cylinder via the control panel. The special design of the shaft ensures that the metal stays in the shaft and is here pre-heated by the flue gas of the melting and/or holding burners. Thereby the energy is drawn out of the flue gases. The pre-heated already pasty aluminium then flows down in the melting chamber.

The metal level in the shaft is supervised by means of lasers. This prevents aluminium parts sticking out from damaging the shaft lid during closing. Furthermore, this reduces energy consumption and maintenance costs.

The holding bath is emptied by tilting the furnace by means of 2 hydraulic cylinders. The tilting process can be very accurately controlled by the operator by means of a manually controlled valve. The discharge opening is at each tilting position below the bath surface and in the centre line, so that the discharge beam hardly changes, the oxides stay in the furnace and there is no false air intake. This contributes to the energy efficiency.

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The holding chamber is insulated with a multi-layer high-quality lining minimizing energy loss. The wall consists of refractory concrete with a high content of Al2O3 with a high resistance against molten aluminium.
For holding the molten aluminium at the required temperature, flat burners are inserted controlled by the temperature of the molten metal separated from the shaft.

The holding chamber is also equipped with a sensor measuring the maximum bath level. When the maximum bath level has been reached, the melting burner is automatically switched off. The burner will not re-start, until the bath level is below the sensor. Through the melting bath regulation of the holding bath, the bath temperature and be regulated independently from the melting burners.

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Available with STØTEK Dosing System

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This model is our traditional shaft furnace combined with our unique, patented dosing system. Here, only the pump is pressurized, which dramatically increases the furnace efficiency, and reduces oxidation, corundum buildup, and metal loss. The system also ensures prompt and accurate dosing (+/-1 %) with a dosing range of 1-65kg/hour.

 

A ceramic pump controls the metal dosing. The metal in the pump is pushed into the transport launder by pressurized air or nitrogen and flows to the filling chamber - casting mould. 

When the dosing is completed, an injector forms a vacuum in the pump, and thereby the pump is refilled with metal and prepared for the next dosing. The dosing cycle is controlled by a Siemens SPS control panel, which at the same time guarantees the communication with the die-casting machine. 

When starting up a new tool at a die-casting machine, a different metal quantity is used in the beginning than during the actual process. The PLC-control can change the dosing quantity for this initial process itself, if the metal quantity is too high or too low and the machine requires this.

Models available:

STØTEK shaft furnaces come in all sizes:

•    Holding capacity ranging from 1.500 kg to 20.000 kg
•    Melting capacity ranging from 350 kg/h to 3.000 kg/h

Other features and benefits:

 Minimal energy consumption
• Size range: 2000kg-10.000kg of aluminum
• Tapered shaft for optimum energy exchange
• Minimal metal loss
• Very low oxidation
• Siemens PLC control system
• Straight wall lining with large cleaning doors
• Teapot spout on tilting design
• Lip axix pouring – bearing in line with sput
• Hydraulic charge elevator
• Kromschroder gas train
• Flat flame burner(s) in holding section
• Accurate holding temperature 
• Excellent service life

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