How is the performance evaluation of refractory bricks?

Refractory bricks, also known as refractory fire bricks, are made mainly from silica and alumina. Dense refractory bricks can generally withstand up to 1770 Celsius degrees. Therefore, they are widely utilized in many industrial fields. In China, as the cement industry develops continuously and rapidly, the demand of refractory bricks is increasing fast. Not only refractory bricks buyers, but also manufacturers hope to produce high-quality refractory fire bricks. Thus, how to evaluate the performance of dense refractory bricks becomes a popular topic.

-        Types of performance evaluation

-        Evaluation methodology

Types of performance evaluation

Before putting the newly produced dense refractory bricks into use, the manufacturers have to evaluate them to make sure they are qualified to put into use.

When it comes to the performance evaluation of refractory bricks, in a broad sense, we roughly have three types of performance evaluation: quality performance, environmental performance and financial performance. To be more detailed, quality performance focuses on whether the refractory bricks have a good quality or not; environmental performance puts emphasis on the possible pollution that refractory bricks might bring; financial performance stresses on the capital costs of producing dense refractory bricks. However, in a narrow sense, as we talk about performance evaluation of refractory bricks, we only refer to the quality performance.

Quality performance evaluation is furthermore split into many different tests, including moisture content test, apparent porosity test, bulk density test, cold crushing strength test, refractoriness test, thermal shock resistance test, loss on ignition test and fired linear shrinkage test. In order to calculate a real number to analyze and compare, each test has its own specified formula. Among the above eight tests, the first three tests reflect the physical properties of refractory fire brick; the result of cold crushing strength test represents its mechanical properties; and the last four tests indicate its thermal properties.

Evaluation methodology

To carry out the evaluation, the materials needed are fired clay samples and Zircon and the equipment required includes furnace, oven, electronic weighing apparatus, hydraulic press, compressive strength machine, atomic absorption spectrophotometer and hammer crasher.

First, we use atomic absorption spectrophotometer to analyze the chemical composition of the sample. In the chemical analysis, if the test result shows that the sample has 48% - 60% Al2O3 content, it should be labelled as Grade III high alumina refractory brick. If it has 60% - 75% Al2O3 content, it is Grade II. And if the Al2O3 content is more than 75%, it is Grade I.

Then, we use jaw crusher and hammer crasher to smash the sample and blend it with zircon at various proportions (10%, 20%, 30% and 35% respectively). Next, we add water (3% - 4%) into the mixture. Mold and press the mix sample with a hydraulic press to 300KN. Air dry the molded bricks for one day and later fire it in a furnace to up to 1200 Celsius degrees. By far, the refractory brick sample is made, and its features can be measured to determine the results of a variety of tests using different given equations.