High frequency infrared carbon and sulfur analyzer is fast and accurate for determining carbon and sulfur in metal materials. In recent years, with the continuous improvement of high-frequency infrared carbon and sulfur, its accuracy has been greatly improved, so that it has better applications in low and high content ranges. Aiming at the inconvenience and inadequacy of the methods used in the analysis of coal, coke and metallurgical materials used in production, this paper discusses the high-frequency infrared carbon and sulfur absorption method for the determination of carbon and sulfur in such materials. Compared with the classical national standard chemical analysis method.
1. Selection of sample size
The carbon content in the sample is about 70% -80%. The test results show that the maximum allowable sample weight of the coal standard sample containing 70.36% carbon is about 20mg, and the maximum allowable sample weight of the carbon standard sample containing 45% carbon is about 30mg. The maximum allowable sample weight of the standard calcium carbonate is about 100mg. In order to minimize the large relative error caused by less sample weight, the maximum allowable sample weight is selected. The carbon content is in the range of 7% -45%, and the sample weight is 80mg. Carbon 45% -80% range, weighing 50mg. Zh
The test results show that the sample is light and has a large volume. The 80mg sample accounts for 1 / 4-1 / 3 of the crucible volume. When the sample amount reaches 200mg, the flux is small, the coverage is poor, and the sample is not completely burned. Too much can cause flooding and contamination of the quartz tube. For this reason, the sample with a sulfur content of less than 4% should be weighed 15mg, and the highest allowable sample should be selected as much as possible to reduce the weighing error. Zh
2. Selection of test conditions
Choice of radon, top oxygen and analytical gas
The test results show that according to the light characteristics of coal, coke, and metallurgical lime, excessive adjustment of the top oxygen and analysis gas pressure will cause sample loss, and the carbon and sulfur results will be low; the adjustment of the top oxygen and analysis gas pressure will be too small, and the sample will burn During the process, the release peaks of carbon and sulfur are not stable, the tailing is serious, and the integration time is greater than 35 seconds. Therefore, for coal, coke and metallurgical light samples, the top oxygen adjustment pressure is (1.0 MPa) and the analytical gas pressure adjustment pressure is: (1.2 MPa).
The radon test showed that with the increase of iron particles, the release curve of carbon and sulfur showed a good peak, without tailing, and the release was completed within 35 seconds. Therefore, like other non-metallic materials, iron box tungsten particles are selected for fluxing.
⑶, the proportion of flux
In theory, fluxes are more conducive to combustion. However, tests have shown that improper mixing will have many adverse effects, such as wasting flux, contaminating and eroding the quartz tube, increasing maintenance times and increasing costs.
① The ratio of iron amount to sample amount The test shows that the minimum optimal iron amount to completely melt the sample is 2.0-2.5 times the sample amount.
② The test of the proportion of tungsten and iron shows that adding too much tungsten particles causes more yellow dust on the crucible wall after analysis, because a large amount of yellow tungsten trioxide is generated, indicating that the tungsten particles are excessive; Many, the crucible wall after analysis is dark brown, and in severe cases, there is a flooded melt on the surrounding wall. The reason is that iron oxides, iron dust and spills are generated, indicating that there are too many pure iron particles. When the pure iron particles are When 300mg, tungsten particles are 1600mg, iron particles are 50mg, and tungsten particles are 2000mg, the crucible after analysis is in the original color, that is, there is no above-mentioned excess product, indicating that the mixing ratio is the best.
In addition, when the amount of iron is too large, black iron slag is generated on the inner wall of the quartz tube. According to test statistics, the quartz tube must be cleaned periodically. If spills occur, the cleaning cycle is shorter. As far as possible to ensure the above optimal ratio, the cleaning cycle of the quartz tube can be as long as more than two or three months, and the wear of the cleaning brush in the tube is reduced.
The optimal ratio of the sample and the flux in this article is: sample amount: pure iron particles: tungsten particles = 50-80mg: 300mg: 1600mg, sample and flux distributio
Experiment according to the following three extremely different joining orders and distribution methods.
① The pure iron particles are first melted on the bottom of the crucible. After cooling, the sample is on it and the tungsten particles are covered. The result is that the slag is coated in the middle layer, the sample has poor melting, the release curve is not sharp, the tailing is serious, the integration time is greater than 39 seconds, and the accuracy is poor.
② The sample is evenly distributed on the bottom of the crucible, pure iron particles are piled in the center, and tungsTen particles are covered. The result is that the frit is in the center and there are unmelted samples around. The release curve is not sharp, the tailing is serious, the integration time is greater than 39 seconds, and the accuracy is poor.
③ The sample is evenly distributed on the bottom of the crucible, pure iron particles are evenly spread in, and tungsten particles are covered. The melted material is smooth and integrated without slag, the release curve is sharp, the integration time is less than 39 seconds, and the accuracy is good. Zh
The results of the sample, the order and distribution of the sample and the flux are not appropriate, and the combustion of the sample is seriously affected during the analysis, the peak of the release curve is unstable, and the tailing is affected, which affects the accuracy and accuracy of the analysis. Operate according to the method (3). The pure iron granules are evenly distributed in the sample, so that the eddy current of the sample area where each iron granule is located, thereby driving the surrounding samples to melt and burn. Therefore, the larger the contact area between the iron particles and the sample, the more uniform the iron particles are distributed, and the more eddy current particles are, the easier it is to burn.
⑸ 、 Light-weight sample scattering problem
On the high-frequency infrared carbon and sulfur analysis instrument, during the analysis operation of the combined furnace operation, as the tube brush is blown down and cleaned at the same time, the pile of heavy metal samples will not have any impact, but it will not affect such light samples. Scatter occurs, affecting analysis accuracy and accuracy. Therefore, the quantitative crucible method was used to cover the crucible. The sulfur of the coal standard sample GBW (E) 110016 was measured 10 times. The test result was 0.03 when the filter paper cover was added, and 0.06 without the filter paper cover.correction
① Carbon calibration Due to the high carbon content in the sample (7% -80%), the test was performed on the benchmark calcium carbonate (C = 12%) and two coal standard samples (containing 43.89% and 70.36% carbon). Results Calibration with reference calcium carbonate can accurately measure 6.88% carbon ferrochrome (GSB03-1562-2003) standard sample and 43.89% carbon standard coal sample (GBW11107L). Calibrated with 43.89% carbon content, a standard coal sample with 70.36% carbon content (GBW (E) 110016) can be determined.
For a coal standard sample with a carbon content of 43.89%, a weighing sample is the same as the calibration standard and b weighing half of the calibration standard. Comparative tests show that the latter exceeds the national standard. The difference is almost 2 times. Therefore, the principle of consistency between the calibration standard and the measured sample must be followed in the calibration, which plays a decisive role in the accuracy of the sample results. Zh
② Sulfur correction Because the conductivity of coal, coke, and metallurgical lime is basically similar to that of iron ore and slag, the iron ore standard is used for calibration. The results show that the coke standard and coal and metallurgical lime standards meet national standards The allowable difference indicates that the ore standard can be uniformly corrected.
This method is used to test and analyze actual samples (such as coal, coke, metallurgical lime, coal ash, coke ash, tile ash, etc.) and compared with the results of the chemical method. The analysis results show that the method is simple and fast. And the accuracy is better than the conventional combustion gas volume method for the determination of carbon and iodine legal sulfur.