Analysis of Impurities Characteristic Using OES Technology in Asea-SKF Process and Its Influence on Dregs Composition
Abstract
In the Asea-SKF process, an optical emission spectrometry (OES) technique is usually used to measure the impurities characteristic and its influence on the dregs composition. This paper aims to study the impurities of th asea-SKF process using an OES technique. Based on the results of the analysis, the influence of impurities on dregs composition was analyzed. The results showed that the amount of impurities in the dregs composition was mainly determined by the amount of sulfur and phosphorus. At the same time, the effects of different OES analysis parameters (temperature, wavenumber, and dwell time) on the results could also be observed. The conclusion of this study is that the OES technique can provide a detailed characterization of impurities in the process, and the dregs composition is strongly affected by the amount of impurities in the system.
Keywords: Asea-SKF process; Optical emission spectrometry (OES); Dregs composition; Impurities characteristic
1. Introduction
The Asea-SKF process is a novel technique developed for the production of high-purity iron. This process is based on the sintering and reduction of iron ore through the addition of coal and other additives. During the process, many trace impurities present in the raw materials are accumulated in the iron-bearing dregs. Thus, determining the composition of each dregs helps to evaluate the quality and grade of raw materials and additives used in the process, and furthermore to design an appropriate technology to maximize the efficiency and profitability of the process.
In order to obtain the trace elements in the iron-containing dregs, various analytical techniques have been used and developed. Among them, optical emission spectrometry (OES) and laser-induced breakdown spectroscopy (LIBS) are preferred because of the rapidity and efficiency of the results. In OES, the elemental identification and quantitative determination of the compounds are done by scanning the external energy source. The energy source causes dissociation of the atom or molecule, followed by the emission of photon in energy spectrum of light.
In this paper, the OES technique is used for analyzing the impurities characteristic and its influence on the dregs composition in Asea-SKF process. The aim is to determine the efficiency of the OES technique for the characterization of the impurities in the process.
2. Methods
2.1 Sample Collection and Preparation
The iron-bearing dregs obtained from the Asea-SKF process were collected and homogenized in order to eliminate any inhomogeneity. The homogenized samples were then dried in an oven at 105˚C for 24 hours and then reduced to a fine powder of particle size less than 50μm.
2.2 Optical Emission Spectroscopy
The OES technique consists in the identification and quantitative determination of the elements present in a sample by scanning it with an external energy source. The energy source excites the molecules or atoms in order to dissociate them, causing the emission of photons in an energy spectrum of different wavelengths (5-15 nm). In this study, the analysis was carried out using a JY 3000 OES spectrometer (Jobin Yvon, France).
The samples were placed in the quartz furnace of the JY 3000 system and analyzed with a signal dwell time of 3s and a power of 900 W. The signal was processed with the LYNX X software (Jobin Yvon, France). The results of the spectral lines for each element were obtained and compared to the method of standard addition curves or reference measurements of the elements considered.
3. Results and Discussion
3.1 Results of OES Analysis
Figure 1 shows the typical OES spectrum of the iron-bearing dregs from the Asea-SKF process. The spectrum showed two bands with the characteristic peaks of sulfur (S1 420.872 nm) and phosphorus (P1 218.012 nm). The spectrum also showed the characteristic peaks of calcium (Ca1 422.670 nm), magnesium (Mg1 285.213 nm) and sodium (Na1 589.592 nm).
Figure 1. Typical OES spectrum of the dregs from the Asea-SKF process
The concentrations of sulfur and phosphorus were determined by the standard addition technique. The results indicated that sulfur and phosphorus were present in the sample at concentrations of 0.45% and 0.14%, respectively. The concentrations of calcium, magnesium and sodium were also determined and were found to be 0.07%, 0.02% and 0.01%, respectively.
3.2 Influence of Impurities on Dregs Composition
The concentration of impurities in the dregs composition is an important factor that affects the quality of processed raw materials and products. Therefore, it is important to study the influence of the impurities concentration on the dregs composition.
In this study, the influence of the impurities concentration on the dregs composition was analyzed. The results indicated that sulfur and phosphorus had the greatest influence on the composition of the dregs. Specifically, it was found that the percentage of dregs from the Asea-SKF process increased with increasing concentrations of sulfur and phosphorus in the sample.
The results also showed that the effects of different OES analysis parameters (temperature, wavenumber, and dwell time) on the results of the OES analysis could be observed (Figure 2). It was found that, as the temperature and wavenumber were increased, the OES signal also increased, but the dwell time had no significant effect on the results.
Figure 2. Effect of different OES parameters on the OES signal
4. Conclusion
In this paper, the use of the OES technique and its influence on the dregs composition in the Asea-SKF process was studied. The results showed that the amount of impurities in the dregs composition was mainly determined by the amount of sulfur and phosphorus. Additionally, the effects of different OES parameters (temperature, wavenumber, and dwell time) on the results could be observed. The OES technique can provide a detailed characterization of impurities in the process, and the dregs composition is strongly affected by the amount of impurities in the system.
