Chemical and structural characterization of Bangladesh zircon and its application

Abstract

Zircon is one of the most important among the heavy minerals occurring in the beach sand along the coastal belt of Bangladesh. The prescnt work attcmpts to make chemical and mineralogical eharaeten7..ation of zircon benelkiated at the Cox's Bazar Pilot Plant of Bangladesh Atumk Energy Commission (BAEC). The mineral is investigated by means of chemical analysis, optical microscopy and X-ray diffraction (XRD). Potentiality of Bangladesh zircon as a raw material for zirconia, opacilier and re1i:actury brick production is also examined. From the chemical analysis it is found that Bangladesh zircon has 95.88% purity. The main impurity in Bangladesh zircon is titanium oxide (3.01%). This is followed by iron oxide (0.42%). Tnlce amounts of other oxides are also found. From the mineralogical study it is found that Bangladesh zircon have an elongated, prismatk shape with pyramidal termination in half of the grains and the rest are more or less rounded. Some fractured and irregular grains arc also found. Bulk sample of Bangladesh zircon in the as-received condition shows golden yellowish brown color. However, individual grains were found tu be almost colorless an d tnmsperent under polari7ed light. XRD study confmned good crystallinity in the sample. Under the microscope, it is found that in Bangladesh zircon, zircon grains constitute 94% and tutal impurities amount to 6%. This result agrecs fairly well with the chemical analysis resuIL~. The main impurities in thc prcsent sample of Bangladesh zircon are found to'be oxides of titanilUTl(both rutile and ilmcnite). This is also consistent with the finding~ uf chemical analY8is. Further, monazitc was identified as an important impurity under the microscopc. Most of the impurities found in Bangladesh zircon exist as discrete minerals. As a result, it should be possible to remove these impurities fairly casily by physical mineral processing methods and thereby impnwe the grade of Bangladesh zircon. The iron bearing coating found on ,orne zircon grains can be removed by acid washing. In the disintegration cxperiments, it has been found that the heating pcriod of 30 minutes is not sufficient to result in eomplele di8inlegration of Bangladesh zircon into zirconia even at the highest temperature (1500"C) and the largest sodium oxide concentration (30%) used in the present 8tudy. Practical experiments have demonstrated that Bangladesh zircon i~ quite 8atisfactory for preparation of zircon flour in ce"lmic indmtries. Zircon flour made from 13angladesh zircon can effectively replace imported zircon 110ur, if adequate size reduction and purification is earned ouL Bangladcsh zircon can also be used successfllily ji,r preparation ofrelmdory bricks for high temperature use.