Hearth type furnace

Hearth type (or reverberatory) furnaces exist in various sizes and shapes. Large hearth type furnaces allow rapid melting and can handle bulky charge material, but the direct contact between the flame and charge material may lead to high metal losses, gas pick-up and to considerable oxide contamination. Temperature control can also be difficult. This type of furnace is used less because of its relatively low thermal efficiency (around 1100 kWh/tonne). The hearth type furnace is also used for copper alloy melting (see Section 3.5.1). [175, Brown, 1999] 

Compound Emission level (mg/Nm ) Mass flow fgdi) Yearly mass flow (tonne/yr) 

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The hearth type furnace is also known as a reverberatory or bale-out furnace. It is a static furnace with direct heating. Hot air and combustion gases from oil or gas burners are blown over the metal (melt) and exhausted out of the furnace. The hearth t5q)e furnace finds its main application in non-ferrous metal melting. A typical furnace design is given in Figure 2.18. 

Figure 2.18 Cross-section of a hearth type furnace [175, Brown, 1999]...

Units Rotary furnace Hearth type furnace Shaft fiimace Crucible furnace ... 

Table 3.24 gives the emission data for a 450kg/h oil-fired hearth type furnace melting aluminium, and working without a flue-gas treatment system. 

The production of refractory waste is 8 - 9 kg/tonne of molten metal for induction melting and 7.5 kg/tonne of molten metal for oil-fired hearth type furnaces. 

Fluxless re-melting Re-melting of Mg scrap under a covering gas in a hearth type furnace applicable only to class 1 scrap. Advantages are the low additional investment and low energy consumption... 

This technique applies to new and existing crucible and hearth type furnaces. 

For the melting of copper, lead and zinc and their alloys, induction or crucible furnaces are used. For copper alloys, hearth type furnaces are used as well. The selection depends on technical criteria. 

Hearth type furnace melting of aluminium and copper... 

Hearth type furnace static furnace with direct heating, also called reverberatory furnace and bale-out furnace... 

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