Castable vs Brick Refractories in Your Rotary Kiln

One of the most critical components of a rotary kiln is its refractory. The refractory is a lining within the kiln drum that serves two overlapping purposes: it takes the heat within the kiln and continuously reflects the heat inwards, while also preventing the heat from escaping outwards to the vulnerable outer shell.

So, a proper refractory is necessary both to maintain the heat profile within your rotary kiln, as well as preventing the heat from causing damage.

As one of the top providers of rotary kiln services in America, Kiln Technology Company Company Co has years of experience helping our clients choose and install the right kind of refractory for their purposes. There are two basic types: castable and brick, and they each have their advantages and disadvantages.

Castable vs Brick Refractories: Which Is Right for You?

I – Brick

Brick refractories are, as the name suggests, made from a series of bricks installed within the interior of the kiln. These bricks are specially formulated, molded, and fired to precise specifications capable of standing up to the heat within a kiln.

Overall, brick refractories are more durable than the alternative. In particular, they are much better than castable refractories at standing up to abrasive materials which could break down a castable refractory. As such, brick is always recommended when working with abrasive substances.

However, brick does have two drawbacks: first, brick refractories are substantially more expensive to install than castable, since each brick has to be hand placed – an operation that can potentially take several days of difficult labor. Also, the bricks are only held in place through the friction and pressure of nearby bricks, like a Roman arch. So, if one brick should come loose or become damaged, it can create a cascade failure as nearby bricks also come loose – necessitating a long shutdown for difficult and expensive repairs.

II – Castable

Castable refractories are essentially a form of concrete, although one specifically formulated for kilns. They are mixed with water and then poured into the kiln. Large Y-shaped anchors positioned throughout the kiln interior hold the material in place, much like rebar holds concrete together.

Castable refractories are significantly cheaper and easier to install, although they do require several days of curing before the kiln will be ready for use.  Also, should the refractory become damaged, it is much quicker to repair than brick. Again, much like concrete, the damage can be repaired simply by pouring on a patch and letting it cure.

Unfortunately, castable refractories are less strong than brick and more prone to damage. Still, the overall cost-savings are often compelling, when working with materials that aren’t hostile to the castable material.

Best Applications for Castable or Brick Refractories

Castable refractories are ideal for intricate shapes and quick installation processes in your rotary kiln. They work well for areas needing frequent repairs or modifications. In contrast, brick refractories are better suited for areas that endure high temperatures and constant wear. Their durability makes them a preferred choice for the main body of the kiln that requires less frequent maintenance and rotary kiln services.

How to Choose

When choosing between castable and brick refractories, assess the operating conditions of your kiln. If the environment is highly abrasive or chemically aggressive, go for the resilience of bricks. For kilns with complex geometries or for quicker repairs, castables offer a more practical solution. The decision should be based on the specific performance requirements of your kiln’s operation.

Factors to Consider

Consider thermal efficiency, with bricks generally providing better heat retention. Also, evaluate installation demands; bricks need skilled masonry, while castables can be mixed and placed with less specialized labor. Maintenance frequency is another factor, as bricks tend to last longer under harsh conditions, reducing the need for repairs. Lastly, weigh the upfront costs against the expected lifespan of the lining, as initial savings on castables might not translate into long-term economy due to more frequent replacements.

Kiln Technology Company Company Provides the Rotary Kiln Services You Need

We are your source for expert rotary kiln services, spare parts, repairs, and decommissioning. At any stage of a kiln’s lifespan, we’re here to assist in any way you need. Just contact us to discuss the issue!