A Review of Top Submerged Lance (TSL) Processing—Part II: Thermodynamics, Slag Chemistry and Plant Flowsheets

Round 1

Reviewer 1 Report

This is very extensive review on the flowsheet, thermodynamics and slag chemistry of TSL processes for various metal extractions, which will contribute to the field of nonferrous metallurgy. Basically it can be accepted for publication. A couple of suggestions regarding FactSage calculations:

(1) The quality of FactSage plots was very low. Please export figures with higher quality. Sometimes, the marker of equilibrium phase field covers the plots.

(2) The databases employed for phase diagram calculation by FactSage should be displayed.

(3) It will be nice if more discussion can be made when showing the operation window in phase diagram (optional).  

Author Response

1. The quality of FactSage plots was very low. Please export figures with higher quality. Sometimes, the marker of equilibrium phase field covers the plots.

Answer: We thank the reviewer for this comment. In the revision, all figures are submitted (zip file) in high-quality “PNG” format.

2. The databases employed for phase diagram calculation by FactSage should be displayed.

Answer: The database selection is same for all FactSage plots and was already mentioned in the Abstract section (see lines 21-25). Therefore, they are not repeated on every FactSage plot.

(3) It will be nice if more discussion can be made when showing the operation window in phase diagram (optional).  

Answer: Again, we thank the reviewer for the comment. We have expanded the discussion in four cases as noted below.

a. We have added the following sentence with regard to Fig. 5 (see the text just before Fig. 5): "As shown by noting the range of the operating window with regard to attained matte grade, matte grades attempted within TSL smelters are less than other reactors employing high levels of turbulence such as the Noranda-Teniente smelter [16]., which also aids these reactors to attain a low level of copper oxidation."

b. In addition, in section 4.1 when referring to the first stage of lead smelting the following bullet point was added before equation (27):

• "Finally, it is interesting to note that the operating TSL window with regard to the slag (see Figure 16) extends also to a slag, spinel two-phase region with the smelter being able with such a more viscous slag system also due to the inherent aspect of induced turbulence."

c. Also with regard to Figure 30, the following sentence exists before the appearance of that figure, which indicates the progression of the slag-fuming process to recover zinc.

" Figure 30 shows the change in this slag's composition during the fuming process, resulting in a zinc lean discard slag"

d. Figure 32 refers to the first stage of the AUSMELT: Direct zinc smelting process. The discussion has been extended with regard to the noted TSL operating window noted in Figure 32 (see text after Figure 31) to note:

"Approximately 40 % of the stage 2 slag is recycled to stage 1 to dilute zinc content in stage 1. Dilution in stage 1 is necessary to avoid the formation of precipitated (e.g., zincite [(Zn,Mn)O] or willemite [Zn₂SiO₄]). At the same time, control of the partial pressure of oxygen is necessary to avoid zinc ferrite formation (see Figure 32). Some spinel formation, however, can be tolerated within the TSL operating window due to the turbulent nature of the TSL reactor. [74]"

Reviewer 2 Report

 

1.      In the introduction, PGM and WEEE abbreviations should be employed after the description:

Platinum Group Metals (PGM) and Waste from Electrical and Electronic Equipment (WEEE).

2.      On page 7, line 284, it’s more suitable employing “necessary” instead of “necessitated”. Also on pag 21, line 758. Check in the rest of the text, because there are more cases.

3.      On page 27, line 179 and after, the equations should start as equation 23, and not 26. Equations 23, 24, and 25 are not in the text.

4.      On page 36, figure 23, it’s tough to read the content in green. Please increase the word size, change colour or something to make it easier to check the information.

 

 

 

Comments for author File: Comments.pdf

Quality is very good. Only the change from necessitated to necessary is recommended.

Author Response

We thank the reviewer for the comments; we have provided answers below:

1. In the introduction, PGM and WEEE abbreviations should be employed after the description. Platinum Group Metals (PGM) and Waste from Electrical and Electronic Equipment (WEEE).

Answer: We believe that the reviewer was referring to the abstract section where abbreviations are employed for PGM & WEEE. The comment of the reviewer has been accepted and implemented within the abstract section.

 

2. On page 7, line 284, it’s more suitable employing “necessary” instead of “necessitated”. Also on pag 21, line 758. Check in the rest of the text, because there are more cases.

Answer: We agree with the reviewer and have implemented the requested change.

 

3. On page 27, line 179 and after, the equations should start as equation 23, and not 26. Equations 23, 24, and 25 are not in the text.

Answer: Yes, the equation numbers were corrected. During our internal corrections, a few equations were removed, and the equation numbering had not been properly updated. As noted, this point is corrected within this revision.

4. On page 36, figure 23, it’s tough to read the content in green. Please increase the word size, change colour or something to make it easier to check the information.

Answer: We have taken the comment into account and the Figure 23 is modified as requested.

Reviewer 3 Report

 

1. The abstract lacks of structure and does not show the significance of the study. A background is also needed for the abstract.

2. The innovations of this manuscript are limited. Most of the results have already been described in some review papers. 

3. It would be helpful if Figure 4 could be enlarged. It would make it much easier to appreciate the details.

4. The numbering of the equations should be revised because they were not appropriately cited.

5. References should be ordered sequentially according to the style of the journal. Please check them. 

6. For Figure(s) 1-45. The supplied figures are of poor quality. Could you please check and share us the better quality figures.

7. The authors could benefit from revising their conclusions to be more concise and impactful. While they have made significant progress, it would be helpful to emphasize their successes more strongly.

 

 

 

 

1. The manuscript needs extensive revision for language and grammar.

Author Response

We thank the reviewer for the comments provided. We have addressed these below.

Comment 1: The abstract lacks of structure and does not show the significance of the study. A background is also needed for the abstract.

Answer: We have considered this comment closely. The abstract has been revised. In terms of structure, we have made an effort that the abstract reflects how the manuscript has been built.

In detail, we start off the modified abstract (lines 12-14) by explaining that it will be the metallurgical, chemical, and processing aspects that will be the focus of this review.

Subsequently, up to line 16, the processes where the TSL has found an application (or has been considered for) are introduced; see passage: "These include the primary and secondary production routes of five non-ferrous metals (tin, copper, lead, nickel, zinc), iron making, and two waste processing applications (spent pot lining and municipal solid waste/related ash treatment)"

Immediately after, we included a new sentence to underline the importance of our review, according to our opinion (see lines 16-18: "Thereby, chemistry and processing aspects of these processes are concisely reviewed here, allowing for a clear and in-depth overview of related aspects.".

Within lines 18-30 within the abstract, we first tried to show the differences in scope of Part II compared to Part I. In addition, we attempted to show the methodology employed for analyzing TSL smelter operation and chemistry with regard to the processes discussed above. Hence, the abstract makes it clear that feed, process goals, flowsheets, chemical reactions, and slag chemistry will be at the heart of this review. This is important, considering that the bulk of this paper discusses these aspects.

The final sentence of the abstract (starting line 31) provides the background motivation behind this article, i.e., "In light of the foregoing discourse, this paper encapsulates basic principles and operational details, specifically those pertaining to TSL bath smelting operations within the nonferrous industry, thereby offering valuable insights intended to benefit both scholarly researchers and industry professionals."

We believe that with the realized changes, the abstract prepares the reader for the text to follow and provides a quick grasp of the work realized within the article.

Comment 2: The innovations of this manuscript are limited. Most of the results have already been described in some review papers.

Answer: Reviews have looked at aspects associated with the production routes of certain metals (e.g., copper, see Refs. 15 and 16); research articles have focused on slag chemistry, and several of these are cited here. Production aspects have also been discussed by the industry, predominantly from production plants and equipment suppliers. Recently, a review appeared focusing solely on fluid-dynamic aspects of the TSL reactor (see Ref. 151).

Within this review, we have tried to go beyond existing literature sources in the sense of bringing together fundamentals (e.g., phase diagram slag chemistry, reaction mechanisms, and distribution coefficients) with the existing industrial data for the processes we have covered. This has been done taking into account inherent fluid-dynamic aspects of the TSL reactor (such as increased turbulence and the ability to recover heat from the freeboard to the bath due to splashing among others). Finally, the authors have included aspects associated with first-hand operation experience of TSL smelters and metallurgical operations.

Considering the above, we have attempted to provide a holistic review of TSL metallurgical processing within this article.

Comment 3: It would be helpful if Figure 4 could be enlarged. It would make it much easier to appreciate the details.

Answer: The Figure 4 size is increased accordingly.

Comment 4: The numbering of the equations should be revised because they were not appropriately cited.

The numbering of the equations has been checked and edited.

Comment 5: References should be ordered sequentially according to the style of the journal. Please check them.

Answer: The references have been cross-checked and edited accordingly.

Comment 6: For Figure(s) 1-45. The supplied figures are of poor quality. Could you please check and share us the better-quality figures.

Answer: All figures are submitted (zip file) with high-quality “PNG” format.

Comment 7: The authors could benefit from revising their conclusions to be more concise and impactful. While they have made significant progress, it would be helpful to emphasize their successes more strongly.

The authors have taken this comment into close consideration. We have added a paragraph at the start of the Conclusion and Summary section (see below). We have however, kept the rest of the structure of this section since it summarizes at a glance key fluid-dynamic aspects of TSL processing as well as key chemical/metallurgical aspects of associated processes.

"The TSL furnace has become an industry workhorse based on its inherent attributes and operational flexibility, thereby becoming indispensable in the quest of smelting and refining of metals from primary and secondary resources. Its applications on copper and PGM recycling (black copper smelting) from WEEE, lead production through battery recycling, and zinc recovery from residual streams such as slags render it crucial in the context of coming closer to the ideal of a circular economy. Its more niche applications described here, such as the processing of spent SPL or utilization in the field of municipal solid waste processing, underline this fact. However, as demonstrated in detail, the TSL reactor is at the center of primary production and is indispensable in tin, copper, and lead concentrate processing. Although furnace selection is a case-by-case exercise when designing a flowsheet, the TSL furnace can outperform alternative options due to aspects such as the inherent possibility to mix well a solid or gaseous reductant with the slag system of interest (see the case of tin production in comparison to a reverberatory furnace). A further example is the ability to remove elements through fuming, which is utilized for element recovery (e.g., tin, zinc, and lead) or for impurity removal (e.g., arsenic or antimony) in the case of primary copper production."

English language

The manuscript has been checked and corrected in terms of English language use.

References

The following references have been added to the manuscript (ref number in the manuscript differs):

1. KCM—Innovator in the Pb Metal Production Through Ausmelt Technology and Variable SO2 Concentration Off-Gas Utilization, Nikolay Starev and Georgi Doganov, PbZn 2020: 9th International Symposium on Lead and Zinc Processing, The Minerals, Metals & Materials Series,
2. Refractory Challenges in Lead and Zinc Furnaces, D. Gregurek, K. Reinharter, J. Schmidl and A. Spanring, PbZn 2020: 9th International Symposium on Lead and Zinc Processing, The Minerals, Metals & Materials Series,
3. Insight on the reduction of copper content in slags produced from the Ausmelt converting process, H. B. Yuan, B. Cai, X.-C. Song, D. Z. Tang, B. Yang, Journal of Mining and Metallurgy, Section B: Metallurgy 57, no. 2 (2021): 155-162.
4. Zhukov, V.P., Kolmachikhin, B.V. & Kolmachikhina, É.B. Hydrogasdynamic Regularities of Melt Blowing in “Ausmelt” Furnace by Cold Modeling Methods. Metallurgist63, 1220–1226 (2020). https://doi.org/10.1007/s11015-020-00944-7
5. Rukini, A., Rhamdhani, M.A., Brooks, G.A. et al.Lead Recovery From PbO Using Hydrogen as a Reducing Agent. Metall Mater Trans B 54, 996–1016 (2023). https://doi.org/10.1007/s11663-023-02745-0
6. Nicol, S.; Hogg, B.; Mendoza, O.; Nikolic, S. Extraction and Recovery of Critical Metals from Electronic Waste Using ISASMELT™ Technology. Processes2023, 11, 1012. https://doi.org/10.3390/pr11041012
7. Nicol, S., Corrie, D., Barter, B., Nikolic, S., Hogg, B. (2022). Adaptability of the ISASMELT™ Technology for the Sustainable Treatment of Wastes. In: Lazou, A., Daehn, K., Fleuriault, C., Gökelma, M., Olivetti, E., Meskers, C. (eds) REWAS 2022: Developing Tomorrow’s Technical Cycles (Volume I). The Minerals, Metals & Materials Series. Springer, Cham. https://doi.org/10.1007/978-3-030-92563-5_8
8. Nicol, S., Ryan, T., Hogg, B., Nikolic, S. (2023). Towards Net Zero Pyrometallurgical Processing with the ISASMELT™ and ISACYCLE™. In: Fleuriault, C., et al.Advances in Pyrometallurgy. TMS 2023. The Minerals, Metals & Materials Series. Springer, Cham. https://doi.org/10.1007/978-3-031-22634-2_2
9. Effect of MgO on physicochemical property and phase transformation in copper slag, HaipeiZhang, Bo Li, Yonggang Wei, Hua Wang, Yindong Yang, Journal of Materials Research and Technology, Volume 18, May–June 2022, Pages 4604-4616, https://doi.org/10.1016/j.jmrt.2022.04.148
10. Wan, Z., Yang, S., Kong, D. et al. Numerical Study of Bath Dynamics in the Industrial-Scale Top Submerge Lance Furnaces. Metall Mater Trans B 54, 2159–2173 (2023). https://doi.org/10.1007/s11663-023-02823-3