Mica slip plane for ferrous and non-ferrous foundries
An effective application for coreless induction coil furnaces
Mica-based linings are flexible, easy to handle, and have replaced asbestos in most countries of the world hence contributing non-hazardous products to maintain the health of foundry personnel.
Non-toxic mica rolls are delivered 1 m wide and 25 m long and serve as:
- Slip-Plane: Glass fiber reinforced mica with high tensile strength,
- Safety-Layer: protecting the coil against refractory material movements
- Separating-Layer: gas diffusion barrier
- Isolation-Layer: electrical and thermal protection
- Protection Layer: compensates bath movements (mainly vertical)
- Mica Foil Combi G (Mica/High-temperature CaSi-paper).
- Mica Foil PGM (Phlogopite/Muscovite mica, glassfiber-reinforced)
Sensitive, water-cooled copper coils in induction furnaces are protected by a concrete wall (coil grout) against refractory (thermal insulation). Removal of the worn refractory material with a hammer drill is expensive and may cause damage. A tear resistant, mica-based, layer enables separation of residual (sintered) refractory from the concrete wall when pushed out and in such protects the coil, elongates service life of the refractory in the crucible and reduces maintenance costs.
When lining coreless induction coil furnaces, SiO2 - based refractory material is inserted locally into the crucible and compacted to form the thermal insulation of the coil from smelt. The approximately 10 cm thick insulation degenerates, depending on the nature/aggressiveness of the smelt, after some 200 applications, 2-6 weeks with melting (usually medium frequency) furnaces.
Removal of the old, used, mass and slag and following relining of a crucible furnace with heat insulation demands caution and experience. Getting the coil grout surfaces sufficiently smooth, so that no defects in the coil wall arise, is labor- and time consuming.
Mica foils provides an asbestos-free and biodegradable mica-based layer to serve as slip-plane of used refractory during demolition. The slip-plane material consists of glass fiber reinforced mica paper (ca. 0.3 mm to 0.5 mm thick) laminated with heatresistant silicon binder. It may be combined with 2 mm Calcium-Silicate-paper when required at larger furnaces, where the wall (coil grout) is rather uneven.
This, generally 1 m wide and odorless, "wallpaper" is delivered on a 25 m long roll that is cut to required size and mounted vertically on the furnace wall (Fig. 1). It is fixed at the top with glue (water- and halogen free) or tape. Mica side shows to the interior of the furnace (Fig. 2). The mica coating ensures good sliding between the refractory material and the coil grout.
|Figure 1: The mica "wallpaper" are
delivered on 25 m long rolls, 1 m wide.
|Figure 2: The 100 cm wide strips, cut and mounted perpendicular to serve as a sliding layer.|
Slip-plane Mica Foil Combi G is a flexible, cold formed laminate comprised of phlogopite and calcium silicate fiber with a special silicon binder. The approximately 2.3 to 2.5 mm thick fiber for the isolation of induction furnaces tolerate temperatures up to 1 050°C, compensates surface unevenness of the concrete wall which is only 2 cm thin and thus reduces cavities.
Mica Foil PGM, is about 0.3 mm to 0.5 mm thick, glass-fiber reinforced and comprised of phlogopite and muscovite layers glass reinforced in between. It is preferably used for smooth interior walls of the furnace to be found usually in smaller furnaces (<2ton).
Both Mica-based slip-planes further compensate refractory movements caused by the permanently active smelt.
Effective and at the same time harmless to health and ecologically safe. The asbestos-free insulation fibers and insulation foils for induction furnaces are based on muscovite or phlogopite mica. Mica is a layered silicate with a high electrical resistance. It is heat resistant and in addition resistant to almost all media, such as alkalis, gases, oils and acids.
According to Hazardous Substances 91/155/EEC Regulation, mica has no health risks, both in storage and during installation and removal. Thus, no special measures have to be taken with respect to the removal of the insulation fibers and insulation films in induction furnaces. The material decomposes in nature into its individual components and can be safely disposed as construction debris and municipal waste landfills.
Continental Trade Sp. z o.o. supplies mica products worldwide since 1995 and occasionally expands it’s product portfolio with adjacent insulation products for the melting shop, when demanded.
We invite you to cooperation. We are waiting for your telephone (+48 22 670 11 81) or e-mail (email@example.com) inquiries. All contact details are available on our website on the Contact page.
Team of Continental Trade Sp. z o.o.
ul. Krasnobrodzka 5; 03-214 Warszawa POLAND