5 Common Ways to Manufacture Refractories

Refractories are manufactured by various methods. The common manufacturing methods include dry press process, fused cast, hand molded, formed and unformed.

Dry press process

This process is ideally suitable to the formation of simple solid shapes. It is particularly suited to clays of very low plasticity. Clay is mixed with a minimal amount of water, then pressed into steel molds under pressures by hydraulic or compressed air rams. Because the dry press process is so simple and involves low capital equipment costs it is the most widely uased high –volume forming process for ceramics.

The manufacturing process has six general steps: 1) mining and storage of raw materials, 2) preparing raw materials, 3) forming the brick, 4) drying, 5) firing and cooling and 6) de-hacking and storing finished products.

Fused cast

Fused cast involves melting refractory material in a electric furnace followed by casting and annealing are treated with oxygen while in the molten state to place the constituents in the most highly oxidized state. This method minimizes the exudation of the glassy matrix of the refractory during service. The raw materials for the refractories may be oxidized before melting by heat treating to reduce the oxygen necessary for oxidizing the molten refractory. High density, small or large shapes are obtained. When appropriate, a finish is made by grinding with diamond tools.

Hand molded

The mold is made by hand. Hand molded refractories do not have the smooth surface of machine made brick. This method is especially well adapted to small

Formed

Firebrick is a common example of formed refractory. Formed refractories are manufactured by either fired or chemically bonded method.

Fired refractories is formed by heating the refractory material to high temperatures in a kiln to form a ceramic bond. This process gives the raw materials their refractory properties.

Chemically bonded refractory brick, also referred to as unfired brick, is formed with the aid of selected additives that set up at room temperature and provide structural integrity, eliminating the need for high-temperature sintering. It offers significant energy savings by eliminating the need for high-temperature processing. In addition, the many methods for modifying the chemical bond can develop new compositions to withstand a variety of severe environments encountered in many industrial processes.

Un-formed

Un-formed refractories, also called monolithic, do not comes in any specific form. Unformed refractories are made and marketed in granulated or plastic forms or as spray mixes. Thus, they can be used as patching materials for maintenance. Common unformed refactories include monolithic-plastic, ramming and gunning mass, castables, mortars, and dry vibrating cements. They are manufactured in various ways.