| Carbonate carbon dioxide is carbon dioxide produced by the decomposition of carbonate minerals in coal at high temperatures. Carbonate carbon dioxide in coal directly influences the coal quality parameters such as the volatile yield, the calorific value and the cohesiveness, and the utilization of coal. Therefore, to determinate the carbonate content in coal accurately not only can determine the quality of coal, but also has far-reaching significance for the follow-up utilization.So far, there have been various methods for the determination of carbonate content in coal and each of them has its own advantages and disadvantages. The gravimetric method has been currently used in China (Standard number GB/T 218-1996), but this method has multi-disadvantages such as wide error sources, low sensitivity, and complicated operation. In view of these deficiencies, a new method to analyze the content of carbonate in coal accurately using the ion chromatography has been designed in this study.Firstly, the device in which carbonate carbon dioxide in coal can be released and absorbed has been established, the carbonate content in the absorbent has been analyzed by the ion chromatography. The optimum air flow velocity of 30±5 mL/min the standard curve, in the concentration range of 10-200 ppm, have been determined after the investigation. The sensitivity S, the precision RSD, the detection limit DL(35) and the relative error of the ion chromatography are 0.65617,2.26%, 3.18 ppm and ≤15%,respectively, after careful determination. The standard CaCO3 has been used as the reference by this method, and the result was satisfactory.In addition, the comparison between the method of ion chromatography and that of GB/T 218-1996 has been performed using five kinds of coal samples from different regions. The results show that the ion chromatography method has the better sensitivity and precision, higher accuracy, wider range of application, and improve the detection efficiency to some extent. |
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