Direct Heating in Ceramics Industry When people hear the term “ceramic” they tend to think of kitchenware, but what may be thought of as an industry of only cutlery, culinary and dinnerware actually has many diverse applications. Ceramics are used in many heavy-manufacturing industries like space and aviation equipment manufacturing, mining, aerospace, medicine, refinery, food and chemical industries, packaging, electronics, defense installations and many more. Ceramic are used in a wide variety of industries primarily because it is can withstand high temperatures, but it is also an excellent insulator. The diagram portrays the steps involved in the production and manufacture of ceramics. Though, the diagram is pretty generic, it does encompass all details of this process. Ceramics begin as powders, mostly made up of a base of Zirconia or Alumina, which are mixed with other materials before being processed. After being ground, mixed, filtered and granulated, these powders are dried via spray dryer. Ceramics are not chemically sensitive materials and thus, the by-products of combustion will not alter the output. Therefore, direct fired air heaters are the most economical and effective type of heater used in this process. The “Forming” process usually involves applying the same amount of pressure from all directions to the powder. The high force causes the powders to be compressed into the desirable shape. Next, during the “Green Body” phase, the un-sintered ceramic is taken out of the die casting and glazed. This phase is called the “green” phase because no firing equipment is used. The “Sintering” process is where the most intensive action happens. Sintering, or firing, is where the mixture of the ingredients is exposed to over 2500oF – over 3000oF for long periods of times in a kiln. The kiln used in ceramics manufacturing typically uses a direct fired air heater, as well. Use of other
methods has being explored, but direct fired heating remains the most efficient option, as it does with the spray dryer.
The firing or sintering is responsible for the mechanical strength, abrasive resistance, dimensional stability, water another chemical resistance and resilience, and finally, heat resilience. The last two steps consist of “Finishing” and “Final Quality Control”. During the “Finishing” phase the ceramic form is altered to fix blemishes and to remove unwanted residue. This phase also involves glazing. Glazing is done by covering the ceramic item with a glass coating and then re-firing the item to 1500oF to over 2500oF in order to sinter the glazed coating. This re-firing process also uses a direct fired air heater. The final step is an examination of the end product to ensure the ceramic piece is up to standards. As we discovered, direct fired air heaters are very important in ceramics manufacturing. For more information about direct fired air heaters, please call Stelter & Brinck at 513-367-9300 or visit: http://www.stelterbrinck.com/direct-fired-air-heaters.htm Please note that Stelter & Brinck also manufacures oxidizers, which are also used in ceramic manufacturing, as the process emitts VOCs. You can learn more about catlaytic oxidizers here: http://www.stelterbrinck.com/thermoxi.htm
Key Words: Ceramics Manufacturing, Spray Dryer, Kiln, Direct Fired Air Heater, Forming, Sintering, Catalytic Oxidizers, Thermal Oxidizers, Stelter, Brinck, Stelter & Brinck