What Are Refractories and What Are They Used for?
Refractories are ceramic materials designed to withstand extremely high temperatures. In general, they are made up of nonmetallic minerals including alumina, silicon carbide, bauxite, dolomite, magnesite, and zirconia. Refractories are most commonly used in the metal production process.
More specifically, refractory brick and dry mix cement are used to assist in the containment of molten metal. For example, an electric arc furnace (EAF) must be lined with refractory brick to protect the furnace structure during the steel melting process. Steel ladles are also lined with refractory bricks to protect their structural integrity as they melt and transfer liquified metals.
Refractory products are commonly packaged in multi-wall paper bags, poly bags, and FIBC bulk bags. Each year millions of multi-wall paper pasted valve bags and poly valve bags are utilized by the large refractory producers such as Resco Products, Saint Gobain, Vesuvius, and Harbison Walker.
Southern Packaging proudly supports these types of accounts with pasted valve bags, bulk bags, and other bulk packaging products.
How Are Refractories Made?
Monolithic refractories including cement, castable mortar, and other dry mixes are manufactured through a closely controlled chemical process.
Raw materials are blasted from quarries and mines. Once the minerals have been blasted and fragmented, they are transferred to a processing facility. The minerals are crushed, pulverized, and screened to ultra-fine powders. The powders are then quickly packaged industrial bags for transport. Refractory cement is so fine that 1 pound of cement contains 150 billion grains.
How Are Refractories Packaged?
Refractories are packaged in a range of paper and poly bag styles. These styles include:
Multi-Wall Pasted Valve Bags for Refractories
Refractory cement bags make up a significant portion of all multi-wall paper bags produced in the world each year. The most common bag style for packing refractories is a Pasted Valve Stepped End bag (“PVSE” or “valve bag”).
Dry products commonly packed in valve bags include:
- Fire Clay
- Thermal Ceramics
- Refractory Cement
Valve bags are packed on equipment that deposits material into the bag via a horizontal filling spout. Valve packing equipment can range from manual, hand-spouted equipment to modern fully-automated equipment. Valve bags are filled through an opening located in the top corner of the bag. Product is pumped or forced into the bag via air pressure, impeller, or auger. When the bag is discharged from the packing equipment, forces generated by the product inside the bag allow the valve opening to self-seal. Cement is most commonly packed using impeller and air-packing equipment.
In general, monolithic refractories are aerated before they enter the bag. In order to pack properly, oftentimes the paper plies of the bag are perforated to dissipate air entrained in the product. Most refractory cement bags include a polyethylene film barrier for moisture protection. The film ply is typically buried in between the paper plies.
The valve bag construction results in a squared-up bag, which palletizes very securely and can be printed with product information on the side or end panels for easier product identification in pallet loads.
FIBC (Bulk Bags) for Refractories
A Flexible Intermediate Bulk Container or “FIBC” is an industrial packaging product made from woven polypropylene (plastic) fabric. The fabric components are sewn to form the shape of a large bag. The purpose of the bag is to store and transport dry flowable products such as refractory cement, sand, resin, and food ingredients. FIBCs can be designed to carry loads up to 5,000lbs.
Like valve bags, FIBC bulk bags are widely used for packaging dry cementitious products. Bulk bags are most often used to package common refractory-related products including:
- Carbon Black
- Refractory Cement
- Monolithic Refractories
Bulk bags are filled on equipment that deposits material into the bag via vertical filling spout. FIBC packing equipment can range from manual equipment to modern fully-automated equipment. Bulk bags are filled through an inlet spout or open duffle located on the top of the bag. Product is dropped or pumped into the bag using gravity or air pressure respectively. When the bag is discharged from the packing equipment, the bag is tied off at the top to prevent contamination or moisture intrusion. Bulk Bags can be equipped with a discharge spout for easy, safe release of the packaged product.
Due to the moisture sensitivity of cement-based products, coated or poly lined bulk bags are recommended. Coated bags offer protection against moisture and contamination by sealing the microscopic gaps between the woven PP tapes.
Benefits of Coated Refractory Bulk Bags Include:
- Improves water/moisture resistance of the FIBC
- Reduces likelihood of product contamination
- Reduces fraying of PP tapes
- Helps maintain product freshness
- Eliminates dusty, unsightly packaging
Coating only acts as a limited moisture and dust barrier. Coating alone will not make the bag waterproof and certain ultra-fine products may sift through the coating. When product protection and sift resistance are critical, we recommend choosing a bulk bag with a PE film liner.
FIBC Liners can be loosely inserted, attached at 8 points using tabs, or glued into the body of the bag. In addition, the liner openings can be cuffed and sewn to the filling and discharge spouts of your bag.
Benefits of PE Lined Refractory Bags Include:
- Eliminates Sifting and Leakage
- Oxygen and Moisture Barrier
- Puncture Resistant Barrier
- Liner can be attached inside the bag using tabs or glue
- Liners can be reused
Are you looking for multi-wall paper pasted valve bags, plastic valve bags, or bulk bags for your refractory manufacturing operation?
In addition to custom-designed packaging, we offer plain on-demand packaging for immediate shipment. We stock over 30 common valve bag sizes and styles for just-in-time delivery.
Please contact one of our sales professionals to assist you or send us an email.