Determination of ash content is a routine task in coal quality analysis. It is easy to ignore the accuracy of its operation, which leads to the decrease of the accuracy of the results. This paper discusses how to improve the accuracy of ash determination from all aspects.

Ash accuracy; degree of accuracy

The ash content of coal is one of the main indexes to evaluate the price by quality, which directly affects the economic benefits of enterprises. Accuracy in the process of coal quality analysis refers to the degree of coincidence between measured values and real values. High precision means high precision, and high precision means not high precision. Because the basic operation of ash determination is simple and easy to master, the accuracy of operation is easily ignored, which increases the measurement error and reduces the accuracy. Based on the above reasons, this paper summarizes many years of practical experience and introduces some experiences to improve the accuracy of ash determination. At the initial stage of Guan Jie (1) heating, the heating speed of coal sample directly affects the amount of sulfur fixation in coal ash. In order to minimize sulfur fixed in coal ash after combustion, the initial heating speed must be slow. We use a muffle furnace with good performance to heat it to 500℃ at different speeds. The ash content of standard coal sample GBWll 1 10b was determined, and the results are shown in table 1. It can be seen from table 1 that the initial heating time is related to ash measurement. 28? The shorter the heating time, the higher the measured ash content. The longer the time, the closer the measured ash is to the standard value. Generally, the test time is 35~45min, which can improve the accuracy of the results. (2) The burnt coal ash absorbed the moisture in the air, and the result was on the high side. The three coal samples in Table 2 are parallel coal samples. Immediately after taking out the ash dish from the furnace, put the 1# coal sample into the dryer and cool it in the air for 5 days. 3# coal sample is directly exposed to air. All three coal samples were cooled to room temperature and then weighed. According to the measurement results, when exposed to the air, the moisture in the air is absorbed, resulting in higher results and lower accuracy. The longer the time, the higher the result and the lower the accuracy. Therefore, the ash tray should be put into the dryer immediately after it is taken out of the furnace. This can minimize errors and improve accuracy. Only the coal samples collected in strict accordance with the requirements of GB 475- 1996 and GB 474- 1996 are representative, and the ash with high accuracy can be obtained after determination. The correctness of sampling is the premise of improving the accuracy of ash. In order to obtain high-precision ash, the weighing of coal samples is also very important. Sample weighing should be accurate and fast. According to the requirements of national standards. In addition, in order to reduce the error and improve the accuracy of determination, the conclusion of 1 stage of coal quality technology (page 2 1 3) 200 1 1 3 is not widely used in China. It is often complicated in application, but as long as the terminology is carefully studied and thoroughly understood, ISO sampling can be regarded as one. Scientific sampling method. The author, Jian Hongliang, 1998 graduated from the Department of Applied Chemistry of Ganwu Rescue Water Conservancy and Electric Power, with a bachelor's degree. He has published funeral essays (date of receipt: 2ooo-o8-20) (continued on page 17), and the critical values of correlation coefficients are 0.754 and 0.8 168 respectively. There is a correlation between t and m, so t1-t1+b (ml-m1)-1-e-m, m-1/49.03-ll. uj b∑(m-m)(T-T)∑(m-m) 1— 19.5438+0+ 1.8944。 The formula can be compared as follows: a1-1.8944b1-2157.21. Similarly: A-2. :747 1b2-3 142。 O3 To sum up, coal slurry. When m≤ 1 155.0, t-1.8944m-2157.21(2) m > 1 155.0, in the long-term production inspection, it was found that the formula for calculating the solid content of coal slurry determined by this method successfully solved the problem that it was difficult to determine the corresponding relationship for the determination of solid content by the concentration tank method. Compared with previous concentration methods, it has the following advantages: (1) The basic data required by this method is collected from actual production. It is widely representative. This determines that the formula derived from this method has strong adaptability in production inspection, so that the measured value of solid content has high accuracy for a long time. Especially in coal preparation plants with stable sources of processing raw materials, it is almost unnecessary to modify the formula for long-term use. (2) The specific formula of this method is derived by using the unified analysis theory, and a clear confidence interval is given, which has strong credibility; Because of the existence of this interval, it provides a clear measurement index for the correction of the formula and avoids the blindness of the formula correction in the original method. (3) This method does not need the exact value of the volume of the concentration tank. Considering the precision and measuring range of the weighing balance, as long as the volume of the concentration tank is unchanged, it can be used in the range of 1 ~ 1.5L, which makes the selection and manufacture of the concentration tank simple and easy. Engineer l994 graduated from Taiwan Province University of Science and Technology, majoring in organic chemical engineering. 1994 to 1997, t-2.7471m-3142.03, technician. (3) At significance level A-0.05, type (the interval is 5=4. 1 1g/L and 3. (Continued from page 28) Instruments and equipment shall conform to GB 2 12-9 1 Check the constant temperature area of muffle furnace, and the instruments shall be calibrated with standard coal samples at least once a month. The operation should strictly implement the standards. In short, the ash content should be determined.