Melting furnaces

Nickel—beryllium casting alloys are readily air melted, in electric or induction furnaces. Melt surface protection is suppHed by a blanket of argon gas or an alumina-base slag cover. Furnace linings or cmcibles of magnesia are preferred, with zirconium siUcate or mullite also adequate. Sand, investment, ceramic, and permanent mold materials are appropriate for these alloys. Beryllium ia the composition is an effective deoxidizer and scavenger of sulfur and nitrogen. 

Flux, J.H. Modelling Studies of Roof Extraction Systems for Arc Furnace Melting Shops. To. x-eraboLirg E.S.C. (Sept. 1974). 

Reverberatory furnaces melt metals in batches using a pot-shaped crucible that holds the metal over an electric heater or fuel-free burner. The flux reacts with impurities. 

Nuclear waste glasses are complex mixtures of more than 30 elements, usually prepared by methods quite different than those used commercially to produce plate glass, for example. Canisters of glass (1-ft-dia x 6-ft-tall) have been prepared by direct furnace melting of a mixture of the waste oxides and an appropriate glass frit. The present experiment simulated this procedure on the laboratory scale. 

Asem, 2 parts, lead, 4 parts. Place in an earthen vessel, throw on it a triple weight of native sulphur, and having put into the furnace, melt. After withdrawing from the furnace, beat and make what you will. If you wish to make figured objects of beaten or cast metal, polish and cut it. It does not rust. 

The electric furnace melting of steel scrap rather than cupola melting is a trend that will probably continue resulting in increasing need for recarburisers. And as the ductile iron segment of the foundry industry grows, so will the demand for consistent materials that allow improved process control. 

Zone refining a modem method of refining where a narrow ring furnace melts a thin disk in a vertical rod of impure material under an inert atmosphere. Impurities are more soluble in the melt, and as the ring furnace traverses the rod the impurities are swept to the end for eventual discard. The process may be repeated until the desired degree of purity has been achieved... 

Oxygen, from the scrap, or the ore, or dissolved in the molten iron from air, reacts with the carbon present in the blast furnace melt to form carbon monoxide. As carbon monoxide bubbles up through the charge it stirs the fluid mass and aids in the rise of silica, manganese oxide, phosphorus oxides, etc., to form a slag layer. While these reactions are going on, limestone decarbonization also occurs and the carbon dioxide formed further contributes to the carbon monoxide formed by its conversion with dissolved carbon (Eqs. 14.1, 14.24). 

The fusible line method can also be used as a calibration temperature. A fusible wire with known melting temperature connects the microbalance suspension wire and inert mass pieces. The fusible wire should locate the position of sample in the furnace. Melting of the wire at its melting temperature causes mass loss, which is recorded in the TG curve. 

Such fissuring causes premature coke abrasion and breakage, reducing permeability in the blast furnace melting zone and influencing the stability of the race-way. Formation and... 

Table 3.14 Typical emission data for induction furnace melting in a ferrous foundry [29, Batz, 1986]...

Table 3.17 Measured emissions for rotary furnace, melting cast iron, without flue-gas cleaning...

Consumption and emission data per tonne of good casting for a 3 t/h shaft furnace, melting aluminium are given in Table 3.22. This also gives the flue-gas emission levels of the raw offgas without cleaning. 

Table 3.23 gives the consumption levels for a two toime melting capacity shaft furnace melting aliuninium. 

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. 

Consumption and emission data per tonne of good casting for a 3 t/h crucible furnace, melting... 

Product type Furnace Melting (tonne/h) Flue-gas (m /h) Abatement (%) PCDD/F (ngTEQ/Nm )... 

Table 4.12 Energy and temperature data for EAF furnace melting with normal slag and foamy slag...

These techniques are applied in other industrial sectors, such as steel and non-ferrous metal production and waste incineration. Judging on a technical basis, they may be transposed to foundry furnace types that show a risk of dioxin formation cupola, rotary and electric arc furnaces melting iron and steel (Section 3.8.2). For new and existing installations primary dioxin reduction measmes, such as efficient combustion, furnace design modifications and scrap quality control have to be taken into consideration on a case-by-case basis, before turning to secondary measures. 

The cost and consumption data for a bag filter installation on a melting unit of crucible induction furnaces, melting 15 t/h, able to treat 120000 Nm /h are given in Table 4.44. 

Electric arc furnace melting of steel and cast iron... 

Induction furnace melting of aluminium, copper, lead and zinc... 

Hearth type furnace melting of aluminium and copper... 

In the discussion on the re-use of dust and residues, no information was provided on treatment or re-use techniques for dust from induction furnace melting, for dross from aluminium melting, fettling dusts, abrasives or for blasting grit, although a re-use of most of these materials into secondary metal production is possible. 

StrauB, D. (1983). "Emissionsminderung druch Umbau einer Kupolofenanlage (Reduction of Emissions by Reconstruction of Cupola Furnace Melting Plant - Final Report 1018)", Umweltbundesamt. 

Rademacher, H. (1993). "Errichtung und Betrieb einer Absaugung der Induktionsofen-Schmelzerei und Nebenbetriebe (Establishment and Operation of Exhausting the Induction Furnaces Melting Equipment and its Sub-Plants - Final Report 1107", Umweltbundesamt, 50 441-5/168. 

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