Influence of Plasma Heating on the Metallurgical Effects of a Continuous Casting Tundish
Round 1
Reviewer 1 Report
Notes to the authors of the article: Influence of Plasma Heating on the Metallurgical Effects of a Continuous Casting Tundish:
91 Figure 1. Schematic diagram of the specimen obtained: a) metallographic specimen; b) tundish
92 covering flux specimen.
Bad drawing title – incomplete.
e.g. Figure 1. The scheme of obtaining and the appearance of test samples: a) ...., b) ... c) solid tundish covering flux sample ground into powder (since there are three groups of different drawings)
Singular or plural - a problems in many places in the article - samples instead of a sample
2.
95 The total heating power of the group A plasma is 658.42 kW, and the heating time is 10 min. The
96 total heating power of the group B plasma is 620.8 kW, and the heating time is 32 min
poor, unclear descriptions of the experiments and how they were carried out.
e.g. Two groups of experiments were carried out in which different heating powers of plasmatrons were used
3.
102 ….. The morphology and energy spectrum of the inclusions are shown in Figure 2,
103wrapped Al2O3-CaO-MgO. The morphologies of various types of typical inclusions are shown in 104Figure 2.
Twice almost the same content
(EDS) maps of inclusions instead of a energy spectrum of the inclusions
Singular or plural map – maps
100 A1 denotes the group A sample before heating. Lmn.
Singular or plural sample – samples
161 covering flux before and after plasma heating change significantly. The tundish covering flux before
162 heating is loose in texture, and the surface is rougher and has many pores; the tundish covering flux
163 after heating is denser, and the surface is smooth and somewhat similar to the glass state
it is difficult to notice this with such magnification and photo quality
6.
168 Figure 7. Appearance and morphology of the tundish covering flux before and after plasma heating.
fluxes
7.
169 Figure 8 shows the macromorphology of the tundish covering flux samples
the scale in the photos is in micrometers, so the microstructure is visible
8.
Figure 8. Optical mirror images of the tundish covering flux before and after plasma heating.
Figure 8. Optical microscope images ...
9.
184 heating. The on-site high-temperature sampling was carried out by water cooling.
poorly explained, water cooling of the flux in the ladle?! no, not taking a sample of the liquid flux from the ladle and its rapid cooling in cold water
there is only further an attempt to explain and it should be earlier
190 heating electrode. After the sample is collected, it is directly water-cooled. .
10.
189 plasma arc column can reach 20000 K
Yes, this is the plasma temperature but the metal temperature in the ladle is different, so why was the metal / flux temperature not measured with e.g. a pyrometer, thermocouple?
193 crystal precipitation. The peaks of the sample before heating are sharper. The main crystal phase of 194 group A before heating is Ca(Al2Si2)O8, and the main crystal phase of group B before heating is 195 CaAl2SiO6.
There is no data on the flux used in the experiments of groups A and B. Is the same. Which was the cause of the different forms of crystallized forms of covering slags There is no data on the flux used in the experiments of groups A and B. Is the same. What was the cause of the various forms of crystallized forms of covering slags: chemical composition or plasma heating power / process temperature?
12.
205 pressure of 0.21 atm. The liquid line projections of the tundish covering flux before and after the two 206 heating tests are shown in Figure 8.??? 9
liquid line- liquidus line ?
should be Figure 9 insted 8- mistake
13.
Figure 10. The liquid line……
Very bad quality – quality should be improved
14.
215 The plasma heating of the tundish can compensate for the temperature drop of the molten steel,
216 and its ability to raise the temperature of the molten steel has also been confirmed, which can reduce
217 the tapping temperature and realize low superheat pouring
it is known what it is about but a breakneck explanation
15.
229 and after plasma heating. After heating, the morphology is dense, and the surface is smooth. The 230 uniformity of the macroscopic morphology of the heated slag is improved by light microscope 231 observation
Observations on the microscope do not improve the morphology !!!! but showed that the morphology of the slags is ...
The work concerns pyrometallurgy, and thus the process related to temperature. Unfortunately, there are no data on temperature data, and the temperature depends on e.g. the fluidity of the metal, the number of inclusions, the resulting forms of liquid phases and their composition, etc. More important and important than specifying the plasma heating power is the temperature in the tundish !.
Author Response
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Reviewer 2 Report
The manuscript reports some aspects of the influence of the plasma heating in the generation of inclusions in the molten steel and the tundish covering flux to provide technical production guidance for a comprehensive explanation of tundish plasma heating technology.
The manuscript is an interesting and contents are original but major corrections are needed. I suggest some changes:
Materials and methods section
This section is in only one paragraph. This should be divided at least into three paragraphs: the first one about the materials, second about experimental procedure and third about analytical techniques.
In the materials paragraph you should explain the materials. How did you determine the chemical composition of the steel used for the experiments?.
In the experimental procedure a more complete explanation is needed. You should also explain how you obtained A1, A2, B1 and B2 samples (Figure 1). This is partly explained in lines 95-95 from the results and discussion section.
Results and discussion
Line 102. I cannot see the energy spectrum in Figure 2, but the morphology and the distribution of the chemical components.
Figure 2-5. What the first mapping image (grey and pink) mean?
Figure 2. In mapping inclusions why you interpret CaS, I don’t think so. Ca and s have not affinity, especially if you have an oxidant environment, then the compound formed should be CaSO4.
The Al2O3-MgO-CaO inclusions (1st set of images) could be (a) spinel or (b) akermanite formation (Ca2MgSi2O7). Note that the chemical composition analysis of the steel material indicates a relatively high Si content (0.231).
In the Al2O3-CaO-CaS inclusions (2nd set of images) it is probably FeS (or CuS, did you mapping Cu?). If you look carefully you can see that the area enriched in S also is slightly enriched in Fe. The other phase could be mayenite (Ca12Al14O33).
In CaS inclusions (5th set of images) could it be CaSO4?.
In Al2O3-MgO-CaS inclusions (6th set of images) the right half of the inclusion is enriched in ca and S but also in Fe.
The discussion should try to interpret the crystalline phases formed and not only the components.
Line 179. You can never start a section or subsection with an image. Figures should always be placed after they have been cited in the text.
Figure 9. The XRD indicates a high amount of amorphous phase, and then the crystalline phases are more difficult to identify, ex. In A1, this spectrum is also very similar to akermanite. This could be clear if you also mapped Si.
In the figure Caption you must indicate which diagrams belong to samples before plasma heating and wish belong to samples before heating.
References. The format of the reference list must follow the instructions of the authors guide.
References 5 and 10. References should indicate all the names of authors, never “et al”. This paper belong to a proceedings volume, this must be indicated here.
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Reviewer 3 Report
This paper uses SEM-EDS, XRD and FactSage to analyze the cleanliness of the molten steel and the characteristics of the tundish covering flux before and after heating.
The results show that the number density of inclusions in the tundish is significantly lower after heating, improving the floating removal rate of small-sized inclusions; after heating, the surface morphology of the tundish covering flux sample appears transparent and glassy, with uniform morphology; XRD results show that the tundish covering flux after plasma heating exhibits no crystal precipitation and is amorphous and that there is a certain regularity before and after heating; there are no obvious changes in the composition of the tundish covering flux in the liquid phase area.
I can say that this article explores the changes in the size, composition, and number density of inclusions in the tundish before and after plasma heating and the influence of plasma heating on the evolution of the morphology, crystal structure, and composition of the tundish covering flux. This can provide a theoretical basis for the development of tundish plasma heating technology.
English can be improved.
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Round 2
Reviewer 2 Report
I find that the manuscript has been highly improved. Now I only suggest a minor change in figure 9. The peaks in XRD diagrams can hardly be observed. It should be better if you represent in the x-axis only the range between 10 and 60 2Theta.
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