Study On The Whitening Methods Of Iron Removal From The Ceramic Raw Materials

Non-metallic mineral raw materials are fundamental of ceramics, the food of ceramic industry, and the basis of ceramic production. In the past 20 years, China's ceramic industry has made phenomenal progress, in which the output of construction ceramics and daily used ceramics takes the first place in the world. However, such a huge number of ceramic production results in more than 100 million tons consumption of mineral raw materials resources every year in China's ceramic industry. With the increasing scarcity of high-quality raw materials(such as high whiteness, process performance excellent et al), the only feasible solution to this contradictory is to optimize the low-quality mineral raw materials. Iron impurities are the main harmful impurities in the low-quality mineral raw materials. They present in various ways, some are like tuberculosis, and some are disseminated or network-like, distributing in the mineral raw materials. The iron impurities in raw materials not only affect the color of ceramic products after calcined, but also have a strong impact on the dielectric properties and chemical stability of ceramic products, etc. However, the existing iron removal techniques have either a poor treatment effect or high cost, which makes it difficult for the majority of ceramic enterprises to accept them. Therefore, it is in urgent need in modern ceramic industry to solve the difficult problem of how to reduce the amount of iron impurities cost-effectively to the normal level.This paper is in connection with the difficult problem that the needed mineral materials in ceramic industry can not be directly applied to practical manufecture because of a high proportion of iron. In order to solve this difficult problem, we have studied some mineral materials with a high proportion of iron which are used for daily production in Dong Peng Ceramic(Qing Yuan) Co, Ltd.. Firstly, we make a concrete analysis and research on the occurances of iron and titanium in mineral materials by using instrumental analysis methods such as electron paramagnetic resonance spectrometer, differential thermal analysis, X-ray powder diffraction, fourier transform infrared spectrometer, transmission electron microscopy, XRF. The results show that the iron impurities in the mineral raw materials can be divided into two categories, some iron impurities are on the surface of particles of mineral materials in an unbound form as hematite, goethite, etc; the others are in the crystal lattice of mineral materials in the form of structure iron. Then, after some experiments on several types of chloride salts to test the effect of high temperature chlorination, we abtain the optimum treatment conditions by using high-temperature calcination method to calcine the zhouxin white mud materials, meanwhile greatly enhance the white content of the products. Finally, we deal with the ready-made building ceramics materials using the magnetic seed sorting method. And after a large number of experimental researches, we find the best treatment conditions, and finally enable the treated materials to be directly used for the production of high quality building ceramics products under the conditions.