Ferrous Foundry
RSS Dixie has a long and established history in the iron, steel, and non-ferrous foundry industries.
The demands of the modern day foundry require a refractory capable of withstanding aggressive slags, molten metal contact, thermal shock, abrasion, and temperatures up to and exceeding 3000°F.
Iron Foundry Equipment
Cupola
Cupolas are vertical melting furnaces primarily used in cast iron pipe shops and other high production iron foundries. They enable continuous melting once charged with alternating layers of coke, limestone, and scrap metal/foundry returns. The charge is added at the charge door and melts as it works its way to the bottom of the cupola via gravity. Air is blown through the bottom of the cupola via tuyeres which combust the coke and enable melting as the charge falls. The addition of limestone to the charge acts as a flux, lowering the melting point of the iron. The flow rate of the air through the tuyeres controls the melt rate and iron temperature.
The cupola is comprised of distinct zones including the upper stack, charge zone, melt zone, well, bottom, tap hole, front slagger, and iron runner. Cupolas typically require the use of high conductivity refractory materials which pass a lot of heat to the external cupola shell; because of this most cupolas contain a water cooled shell. RSS Dixie can provide refractory materials for all areas of the cupola.
Cupola upper stacks require abrasion resistance and temperature resistance up to 2800°F. Common products include Dixie Gun 28 T along with Alumina-Silicon Carbide offerings such as Dixie Gun BSC-AS and Dixie Gun 65-20.
Refractories in cupola melt zones experience high temperatures, abrasive conditions, and thermal shock. The use of alumina-silicon carbide materials is typical in this area due to their excellent abrasion resistance and thermal stability. Our 54% Silicon Carbide gun mix -Dixie Gun ASC is excellent for especially aggressive melt zones and 34% Silicon Carbide Dixie Gun BSC-AS can be used in lesser conditions.
The cupola well, which acts as a reservoir for molten iron before tapping, and area above the tuyeres experience high temperatures and aggressive slags containing FeO, SiO2, and CaO. The use of silicon carbide containing refractories in these areas is crucial. The extremely high thermal conductivity of silicon carbide refractories enable a high amount of heat transfer from the hot face of the refractory to the exterior cupola shell. This rapid heat transfer essentially freezes off the slag on the surface of the refractory and protects is from further chemical reactions with the aggressive slags. The water cooling on the cupola exterior solves the issue of high steel shell temperatures.
Our resin bonded plastics such Dixie 612 R, Dixie 622 R, and Dixie 652 R offer increasing contents of SiC+C to suit any cupola well. In addition, gun mixes such as our Dixie Gun BSC-AS are also common.
Ram mixes are the most common material in the cupola bottom. We offer Dixie 615 R, Dixie 625 R, and Dixie 655 R rams specifically for this area. In addition, the cupola tap hole and slagger will typically use resin bonded plastics and rams such as those mentioned above.
The iron runner coming off the cupola will typically use high alumina plastics, ultra-low cement castables, and cement free castables such as our Thermogen 70 Plastic, Dixie Crete ULC 85, and Dixie Crete CB 80 respectively.
Coreless Induction Furnace
The coreless induction furnace is the most commonly used melting unit in the modern foundry. They operate via induction heating through a series of refractory lined, water cooled copper coils that surround the melt bath. Coreless induction furnaces enable the melter to produce a plethora of alloys and provide flexibility in the melting process. Many foundries contain multiple coreless furnaces on the melt deck which can be run simultaneously or singularly while the others are being repaired. Coreless induction furnaces are found everywhere from the small job shop to the highest production facility.
The main components of the coreless induction furnace consist of the cover, top cap, spout, working lining, slip plane, and furnace base
The furnace cover often undergoes extreme thermal shock as a result of being constantly moved on and off the furnace. This requires the use of monolithics with high hot strengths, excellent resistance to thermal shock and high temperature resistance. In addition, weight is often a consideration so as not to put strain on the controls when moving the lid off the furnace.
Coarse grained castables such as our Dixie Crete LC 50 C provide an excellent balance between strength, weight, and thermal shock resistance in furnace lids.
Top caps must be resistant to high temperatures, aggressive chemical slags, and abrasion as the cap sits at the top of the melt bath. Plastics are the most commonly used materials in this area because of their excellent chemical and abrasion resistance. Product selection often depends on the alloy being melted in the particular furnace. Manganese steels and other high temperature steels often require high alumina plastics with chrome additions such as our Thermogen CA-7 Plastic and Thermogen CA-9S Plastic for added resistance to corrosive slags. In less aggressive atmospheres, as for certain types of grey irons, high alumina plastics such as our Thermogen 85 Plastic and Thermogen 90 Plastic can be used.
Furnace spouts often see similar conditions to the top cap and as such, many of the aforementioned plastics- Thermogen CA-7, Thermogen CA-9S, Thermogen 90, Thermogen85 -are used. Erosion from metal flow when the furnace is tapped is of primary concern in this area and plastics provide excellent resistance to erosion and abrasion.
The working lining is always a dry vibratable material of varying chemistry. Dry vibratables enable linings to be replaced quickly and efficiently with minimal heat up time. The majority of dry vibratables used in grey, ductile, and malleable iron foundries are chemistries of 99%+ Silica with a boron oxide or boric acid binder for aid in sintering upon heat up. RSS Dixie offers Svenska silica products for these applications.
For foundries producing various alloy steels, dry vibratables in the working lining are often 80-90% fused alumina with magnesia additions for a spinel bond. Dixie Vibe Pak 80A and Dixie Vibe Pak 88 A are our commonly used offerings in these furnaces. The spinel bonding in these materials offers excellent hot strengths and high temperature thermal stability which are crucial properties at the high temperatures associated with steel melting.
Channel Induction Furnaces
Channel induction furnaces act as holding and pouring vessels for molten iron and are located downstream from the cupola or coreless induction furnaces. The channel induction furnace allows the operator to regulate iron temperature and consistency prior to tapping into a ladle for further downstream pouring and production.
The channel induction furnace is made up of the receiver/pour spouts, lid, uppercase, floor, and inductor.
RSS Dixie offers numerous products for the receiver and pour spouts in channel furnaces. Erosion from the inflow and outflow of iron is a primary process concern in these areas. The use of silicon carbide containing castables in these areas is most common because of their superior abrasion resistance. In less aggressive units, ultra-low cement, high alumina castables can be used. Our Dixie Crete LC-80-20 and Dixie Crete LC-91 SC are common silicon carbide offerings and our Dixie Crete ULC-85 is an excellent ultra-low cement option.
The channel furnace lid experiences similar process considerations as the coreless induction furnace lid- weight and some minor thermal shock are of primary concern. Our 50% alumina, low cement castables such as Dixie Crete LC-50 and self-flowing Dixie Crete LC-5001 QD are excellent offerings.
Channel furnace upper cases and floors experience high temperatures, molten metal contact, erosion, and aggressive slags. Typical linings are low cement pumpable materials of the alumina silicon carbide variety. Dixie Crete LC-91 SC and 92-SC are our common selections for these areas.
It is also very common to flash coat uppercases to extend the working life of the refractory. For this we offer various high alumina hot gun mixes such Dixie Hot Shot-TB and Dixie Hot Shot 60.
Transfer and Treatment Ladles
Transfer and treatment ladles are the workhorse of the iron foundry. They enable the movement of molten metal from melting to holding to casting areas. Today’s foundry requires a ladle lining that is robust, insulating-to keep metal hot- and easily replaced or repaired when needed.
Treatment ladles are used to convert grey iron into ductile iron via a reaction between molten grey iron and magnesium or cerium. This reaction product creates the graphitic nodules that give ductile iron its distinct mircrostructure and mechanical characteristics. The reaction of grey iron with magnesium or cerium is volatile and often requires a treatment ladle with a flanged lid to contain it.
Transfer ladles are used for moving iron from one place to the next in the foundry.
The refractory considerations for ladles vary depending on the iron being transported and type of ladle. Most iron foundries use castable working linings ranging from 60-85% alumina with an insulating fiber backup.
Our cement free Dixie Crete CB products are excellent options for the working linings of iron ladles. The lack of casting water, which is replaced by the addition of colloidal silica, allows for extremely quick cure times of 3-4 hours and enables you to get your ladle on heat up and back on the line.
In addition, we can offer numerous low cement/ultra-low cement castable products such as our Dixie Crete LC 6001, Dixie Crete LC-7001, and Dixie Crete ULC-85.
Many foundries use sacrificial MgO coatings to enable easier de-skulling of slag from the refractory hot face. Our Dixie Basicote product line, ranging from 50-75% MgO is commonly used for this purpose. We can also provide all variety of patching and maintenance plasters, plastics, veneers, and mortars.
