Research On Coating Adhering Performance Of Environmentally Friendly Basic Refractory

The aim of this research is to study the coating adhering performance of environmentally friendly basic refractory used in the sintering zone of new dry process cement rotary kiln.At present, direct-bonded magnesia-chrome bricks are being used in the sintering zone of the cement rotary kiln. However in the application of the direct-bonded magnesia-chrome bricks, the pollutant Cr6+ which heavily cause environmental pollution will be created, so the scientific research focuses on develop chrome-free bricks for the sintering zone of new dry process cement rotary kiln. Developed countries have forbidden the use of direct-bonded magnesia-chrome bricks in cement factory. In order to displace the direct-bonded magnesia-chrome bricks in our country , China Building Material Academy have carried out researches on new chrome-free bricks recently.In order to get better new chrome-free bricks, First we studied the coating adhering performance of magnesia-alumina spinel bricks and direct-bonded magnesia-chrome bricks. Though thermal shock resistance of magnesia-alumina spinel bricks is good , the coating adhering performance is bad. Theβ-C2S which exists in the coating will transform toγ-C2S and bring in 13.6% bulk increase, results in the pulverization of coating. The coating adhering performance of direct-bonded magnesia-chrome bricks is good. The Cr exists in direct-bonded magnesia-chrome bricks plays the role of improving the stabilization ofβ-C2S, therefore, the coating can adhering to the hot face of the bricks for long time.We tried out a lot of oxides in the research of new chrome-free bricks in order to make it coating adhering performance good. In the end , we found out La2O3 have the ability to get better the coating adhering performance of new chrome-free bricks. In our study, we found out the new chrome-free bricks have the same coating adhering performance with the direct-bonded magnesia-chrome bricks. We used"sandwich method"to research the coating adhering performance of different bricks. The"sandwich method"means using two brick slices and cement clinker to make a sandwich for studying the coating behaviour. The brick slices which have more cement clinker on the surface have better capability to adhering a coating. We also improved the"sandwich method"to study the coating behaviour of different bricks. We found out that the new chrome-free bricks have the same capability of coating adhering performance with direct-bonded magnesia-chrome bricks.We have produced new chrome-free bricks in a refractory factory, and a good effect has been achieved in the application to a new dry process rotary cement kiln. The new chrome-free bricks have good coating adhering performance have been proved in practice.